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Saturday, July 23, 2022

Community radio

From Wikipedia, the free encyclopedia
 
KRBX Radio Boise volunteers during the station's Spring Radiothon in 2013—direct community support is critical for such local media.

Community radio is a radio service offering a third model of radio broadcasting in addition to commercial and public broadcasting. Community stations serve geographic communities and communities of interest. They broadcast content that is popular and relevant to a local, specific audience but is often overlooked by commercial or mass-media broadcasters. Community radio stations are operated, owned, and influenced by the communities they serve. They are generally nonprofit and provide a mechanism for enabling individuals, groups, and communities to tell their own stories, to share experiences and, in a media-rich world, to become creators and contributors of media.

In many parts of the world, community radio acts as a vehicle for the community and voluntary sector, civil society, agencies, NGOs and citizens to work in partnership to further community development aims, in addition to broadcasting. There is legally defined community radio (as a distinct broadcasting sector) in many countries, such as France, Argentina, South Africa, Australia and Ireland. Much of the legislation has included phrases such as "social benefit", "social objectives" and "social gain" as part of the definition. Community radio has developed differently in different countries, and the term has somewhat different meanings in the United Kingdom, Ireland, the United States, Canada and Australia, where freedom of speech laws and de facto realities differ.

Vision, philosophy, and status

Modern community radio stations serve their listeners by offering a variety of content that is not necessarily provided by the larger commercial radio stations. Community radio outlets may carry news and information programming geared toward the local area (particularly immigrant or minority groups who are poorly served by major media outlets). Specialized musical shows are also often a feature of many community radio stations. Community and pirate stations (in areas where they are tolerated) can be valuable assets for a region. Community radio stations typically avoid content found on commercial outlets such as Top 40 music, sports and "drive-time" personalities. A meme used by members of the movement is that community radio should be 10 percent radio and 90 percent community. This means that community radio stations should focus on getting the community talking and not solely on radio (which is a technological process); the social concerns of community radio are stressed over radio per se. There is also a distinction drawn in contrast to mainstream stations, which are viewed as pandering to commercial concerns or the personalities of presenters.

Conceptions of community in the literature

Communities are complex entities, and what constitutes the "community" in community radio is subject to debate which varies by country. "Community" may be replaced by terms such as "alternative", "radical" or "citizen" radio. In sociology, a "community" has been defined as a group of interacting people living in a common location.

Community radio has been built around the ideals of access and participation. Stations have been run by locals, typically to serve a local audience. However, the internet's availability and popularity has encouraged many stations to podcast and/or stream and audio and make it available globally.

Models

Two philosophical approaches to community radio exist, although the models are not mutually exclusive. One emphasizes service and community-mindedness, focusing on what the station can do for the community. The other stresses involvement and participation by the listener.

In the service model locality is valued; community radio, as a third tier, can provide content focused on a more local or particular community than a larger operation. Sometimes, though, providing syndicated content not already available within the station's service area is viewed as public service. Within the United States, for example, many stations syndicate content from groups such as Pacifica Radio (such as Democracy Now!) on the basis that it provides content not otherwise available (because of a program's lack of appeal to advertisers—in Pacifica's case, due to its politically controversial nature).

In the access (or participatory) model, the participation of community members in producing content is viewed as a good in itself. While this model does not necessarily exclude a service approach, there is some disagreement between the two.

By country

Australia

Community radio station & newspaper office side by side in regional (Young), New South Wales

Community broadcasting is Australia’s third media sector, formally represented by the Community Broadcasting Association of Australia (CBAA). In January 2012, there were 359 licensed community radio stations (including remote indigenous services). A 2002 report found that 20,000 Australians (or 0.1 percent of the population) were involved as volunteers in the community radio sector on a regular basis, and volunteers account for more than $145 million in unpaid work each year. Nationally, more than 7 million Australians (or 45 percent of people over 15) listen to community radio each month.

The role of community broadcasting in Australia, according to CBAA, is to provide a diverse range of services meeting community needs in ways unmet by other sectors. Community broadcasting is sustained by the principles of access and participation, volunteerism, diversity, independence and locality.

Community radio stations may be specialized music stations, represent local music and arts or broadcast talks and current-affairs programs representing alternative, indigenous Australian, environmental, feminist or gay and lesbian interests (filling perceived gaps in commercial or government radio content). 53 percent of community radio stations serve an array of communities of interest, including indigenous and ethnic groups, people with a print disability, young people, older people, the arts/fine music, religious, and the gay and lesbian communities. The remaining stations provide a service which may be described as generalist: addressing the interests of communities in particular areas, but also addressing a range of specialized interests.

Community broadcasting, more than any other form of media in Australia, shapes and reflects the national character in all its diversity. The sector is unique in its capacity to provide fresh programming by and for indigenous, ethnic and RPH communities. Community broadcasting stations have a strong commitment to local news and information, the promotion of local and national music, arts and culture and providing training in media skills.

When a not-for-profit community group applies to the regulating body (the Australian Communications and Media Authority) for a community broadcasting licence, it specifies the community interest it intends to serve. Licensees are selected by the regulator on the basis of suitability and on the merits of the licence application and the capacity to serve identified community interests. Upon grant of a five-year renewable licence each station is required to continue to serve the community interest for which the licence was granted. The Broadcast Services Act establishes the requirement to continue to represent the licensed community of interest and the requirement to encourage participation from the licensed community of interest in the provision and selection of programs as key conditions of the licence. Provisions for Temporary Community Radio Licences in the Act allow, where spectrum is available, for aspirant community groups to develop their facilities and financial and programming models before the regulator considers making a permanent licence available.

Austria

In Austria, community radio was introduced in 1990 through a pirate radio movement. Regular licensed broadcasts began in 1998. Commercials are not permitted, so stations are primarily operated as non-profit NGOs. There are 14 community radio stations operating in the country.

Bangladesh

Workshop for Bangladesh NGOs Network for Radio and Communications staffs

Bangladesh NGOs Network for Radio and Communication (BNNRC) has been struggling for the last 12 years to open up the community media (including Community Radio, Community Television and Community film) and giving focus on its vital role as voices of the voiceless people. BNNRC has been addressing the community radio & community TV access issue for over a decade, almost since its emergence in the year 2000.

BNNRC is in special consultative status with the United Nations Economic and Social Council. BNNRC has been promoting advocacy to the government in relation to community radio with other organizations since its emergence in 2000.

The objective of BNNRC's Community Radio intervention is to address social issues (such as poverty and social exclusion) at the community level, empower marginalized rural groups and catalyze democratic processes and ongoing development efforts.

At the moment, positive and supportive condition is prevailing in our country. Because; Bangladesh Government has already acknowledged the importance of community radio and announced the Community Radio Installation, Broadcast and Operation Policy. Bangladesh is the 2nd country in South Asia in formulating policy for Community Radio. Now 14 community radio stations are on-air in the country, aiming to ensure empowerment and right to information for the rural community. They are broadcasting altogether 120 hours program per day on information, education, local entertainment and development motivation activities. Around 536 youth women and youth are now working with those Stations throughout the country as rural broadcasters.

The prime role of community radio is giving a voice to people who do not have access to mainstream media to express their views on community development. Promoting the right to communicate, expediting the process of informing the community, assisting the free flow of information and acting as a catalyst of change are major tasks achievable by community radio. It also upholds creative growth and democratic spirit at the community level.

As a result, the Ministry of Information of the People's Republic of Bangladesh announced the Community Radio Installation, Broadcast and Operation Policy 2008. Under this policy, the Ministry of Information approved 14 community radio stations for the first time in Bangladeshi history. To ensure the free flow of information to the people, the government enacted the Right to Information Act 2009. Community radio stations are a strong step in empowering rural people.

The reality of today is that the bondage between the community people and local-level community radio stations are getting strengthened day-by-day. Community Radio has now become their part of life. Community Radio becomes the instrument for the livelihood battle of the rural people.

BNNRC established the Community Media News Agency (CMNA), Community Media Academy (CMA) and Monthly Community Media to share development news and building capacity for the Community Media sector in Bangladesh. BNNRC now started advocacy with the Government of Bangladesh to open up community television for development.

Ministry of Information approved 17 community Radio in Bangladesh:

  • Community Radio Sagor Giri 99.2 Young Power in Social Action (YPSA) for Sitakunda, Chittagong
  • Community Radio Nalta 99.2 [Nalta Community Hospital (Satkhira)]
  • Community Radio Mukti 99.2 [LDRO (Bogra)]
  • Community Radio Pollikontho 99.2 [BRAC (Moulivi Bazer)]
  • Barandro Community Radio 99.2 (Naogaon)
  • Community Radio Mahananda 98.8 [Proyas (Chapai Nababgonj)]
  • Community Radio Padma 99.2 [CCD (Rajshahi)]
  • Community Radio Jhinuk 99.2 [Srizoni (Jhinaidhah)]
  • Community Radio Bikrampur 99.2 [Ambala Foundation] (Munshiganj)
  • Community Radio Lokobetar 99.2 [MMC (Barguna Sadar Upazila)]
  • Community Radio Chilmari 99.2 [ Chilmari, RDRS (Kurigram)]
  • Community Radio Sundarban 98.8 Koyra Upazila (Khulna)
  • Community Radio Naf 99.2 Teknaf [ACLAB (Cox's Bazar District)
  • Community Rural Radio 98.8 [Agriculture Information Services (AIS) Community Rural Radio (Barguna District)]
  • Community Radio Meghna 90.0, Charfassion, Bhola [COAST Trust (Bhola District)
  • Community Radio SagarDwip 99.2, Hatyia Island, [Dwip Unnayan Shongstha-DUS (Noakhali District)
  • Community Radio Sarabela 98.8, ([SKS Foundation Gaibandha District)
  • Community Radio Boral 99.2 (Bagha, Rajshahi District)

Earlier, in the 1st batch on 22 April 2010, Ministry of Information has approved 14 community radio stations, the number stands on 16 by adding more 2 stations in the line soon. 14 community radio stations ushered a new era by rural broadcasting 106 hours programs daily within a listeners’ community of 4.6 million of 13 upazila of the country. These programs reflect the rights and scopes of the disadvantaged community people. This neo-media has produced a neo-generation of community radio broadcasters at rural level where a total of 536 youth and youth women are contributing creativity their time, effort and thus taking part in nation-building process. The initiating organizations received approval for primary set up of community radio stations in the 2nd phase are:

  • [Progati Research on Grassroots Ownership and Traditional Initiative for Shaymnagar Upazila, Satkhira District]
  • [Aparajeyo Bangladesh for Pirganj Upazila, Rangpur District]
  • [Bangla-German Sampreeti (BGS) for Tangail District]
  • [SKS Foundation for Sader of Gaibandha District]
  • [Voluntary Association for Rural Development (VARD) for Sunamganj District]
  • [Somaj-O-Jati Gathan(SOJAG) for Dhamrai Upazila of Dhaka District]
  • [Shechashebi Bahumukhi Mahila Samajkallyan (SBSSS) for Boalia Upazila of Rajshahi District]
  • [Jyoti Development Foundation for Sadar Upazila of Kushtia District]
  • [Institute of Development Affairs (IDEA) for South Surma, Sylhet District]
  • [Nazrul Smriti Sangsad (NSS) for Kalapara Upazila of Patuakhali District]
  • [Karmojibi Nari for Bheramara Upazila of Kushtia District]
  • [Bandhan Society for Halimpur, Bajithpu Upazila, Kishoreganj District]
  • [Patuakhali Development Organization (PDO) for Bauphal Upazila of Patuakhali]
  • [Coastal Association for Social Transformation for Sadar Upazila of Cox’s Bazer]
  • [Program for Eco-Social Development (PESD) for Sherpur Upazila, of Bogra District ]
  • [Borendra Unnayan Prochasta for Sapura Upazila of Rajshahi]

Bangladesh NGOs Network for Radio and Communication represents the community media sector to Government, Industry, Regulatory Bodies, Media and Development Partners in Bangladesh. The reality of today is that the bondage between the community people and local-level community radio stations are getting strengthened day-by-day. Community Radio has now become their part of life. Community Radio becomes the instrument for the livelihood battle of the rural people.

BNNRC has been struggling for the last 12 years to open up the community media (including Community Radio, Community Television and Community film) and giving focus on its vital role as voices of the voiceless people and has already established the Community Media News Agency (CMNA), Community Media Academy (CMA) and Monthly Community Media to share development news and building capacity for the Community Media sector in Bangladesh.

Community radio is considered an alternative, effective mass media for the rural disadvantaged population to express their thoughts in their own voice and their own style.

Benin

Radio is the primary mass medium in Benin and sub-Saharan Africa. Of its 55 radio stations, 36 are community stations with programming ranging from news and sports to music and quiz shows. Although there is a need for such stations, it is difficult for them to succeed due to financial and structural problems and a lack of funding.

Bolivia

A well-known example of community radio in Bolivia was the tin miners' radio. Funded by trade union dues and operated mainly at the local and regional level, there were more than 25 such radio stations between 1960 and 1985. Changes in government policy eliminated many unionised mining jobs after 1985 and some radio stations were sold or ceased to exist. In spite of many difficulties, five stations continue to broadcast.

La Voz del Minero, Radio Pío XII, RadioVanguardia de Colquiri, Radio Animas, Radio 21 de Diciembre, and Radio Nacional de Huanuni were some of the most important radio stations created, funded and managed by Bolivian mining workers. In 1949, a station began broadcasting in the mining district of Catavi. During the next 15 years, other districts followed; they bought the equipment, trained young people from their villages, and the workers funded the stations with a percentage of their salaries.

Most of the radio stations began small, with simple equipment. A few received foreign support and evolved into more sophisticated stations, with better equipment. Several built theatres next to their stations, so union meetings could be broadcast live; for example, Radio Vanguardia had a theatre decorated with large murals narrating the story of the Colquiri mining centre. One scene on a mural depicts the attack by Bolivian Air Force planes in 1967 (when the country was under military rule).

During the early 1970s 26 radio stations were in operation, all in the mining districts of the highlands. At the time, the miners' unions in Bolivia were still powerful and considered among the most politically advanced in Latin America. In times of peace and democracy the miners' radio stations were integrated into the daily life of the community, becoming an effective replacement for telephone and postal service. People would receive their mail through the stations and post messages, which were read several times during the day: calls for a meeting of women from the Comité de Amas de Casa (Housewives' Committee); messages from union leaders about their negotiations with the government in the capital; messages of love between young people; the announcement of a new play by the Nuevos Horizontes theater group (often staged on the platform of a big truck, with workers illuminating the scene with their own lamps); and announcements of sport activities, burials, births and festivities.

In times of political upheaval, the union radio stations would become the only trustworthy source of information. As the military captured newspapers, radio and TV stations in the capital and other cities, the only information available would come from the miners' radio stations. They would join the cadena minera ("mining chain") until the army penetrated the mining camps and mounted an assault on the stations, which were defended (sometimes to the death) by the workers. A film by Bolivian filmmaker Jorge Sanjinés, The Courage of the People, reenacts the attack on the mining district of Siglo XX by the army in June 1967. Another film, a documentary by Alfonso Gumucio Dagron and Eduardo Barrios entitled Voices of the Mine and produced by UNESCO, describes their political and social importance. The miners' radio stations would air reports on the political situation; they would also link for live transmissions when an important sporting or cultural event took place in the mining district. Other than that, each station was fully independent of the others.

The miners' radio stations were important because of the importance of mining in Bolivia; Bolivian miners were also influential because for several decades they had a powerful means to communicate their ideas. As the importance of mining in Bolivia declined during the 1980s, the unions were weakened and some of the radio stations disappeared (along with their mining districts).

Brazil

Princesa FM of Ponta Grossa, southern Brazil an example of CR. As indicated the frequency is 87.9 MHz, one of the most common tunings intended for this type of radio in this country.

Law No 9612/1998 defines a community radio station as sound stations belonging to non-profit foundations or associations representing a public contained therein, living in a neighborhood or united by a social cause and that the station presents itself as a spokesperson of these people. It has to operate with a maximum power of 25 watts ERP and its tower will have the limit of 30 meters. These technical characteristics delineate a portion coverage of an urban area, a partial coverage in the municipality. As said, the community broadcaster has a cultural function, there can be no explicit commercial breaks but cultural supports of the content of the grid. Programming times can not be sold to third parties and broadcasting to other stations is prohibited (going against the idea of a "community radio").

They should be open to divergent opinions and divergent lifestyles regarding each of them. The average radius of reach is 1 km (covering a village and a neighborhood in particular). The use for the ideological-political end or to present a specific belief is not allowed. An entity that has interest can send the documents to the Statement of Interest Register (CDI). The requests received appeared in the National Grant Plan (PNO), later a notice will be opened with the documents that should be sent. This does not mean that the institution has obtained the radiofrequency, there will be a selection process to eliminate the competition. Even if after all it is authorized, it will have to be countersigned 90 days until the release of the National Congress, otherwise the applicant may require a provisional license.

The FM frequencies reserved for the service are 87.5 MHz, 87.7 MHz and 87.9 MHz, however, in some regions of Brazil, community radio stations are reserved in the frequencies 98.3 MHz, 104.9 MHz, 105.9 MHz, 106.3 MHz and 107.9 MHz. The frequency is reserved and licensed only by Anatel, the National Telecommunications Agency of Brazil.[15] The history of the Brazilian community is inclusive in a context of Brazilian redemocratization in the second half of the 1980s. In the struggle to institute the same, a movement began in 1991, organizing itself in the form of a forum, in 1994 the judiciary gave a vowable vote to the establishment of radios and their proponents to become legal. The largest city in the country, São Paulo because of the lack of frequency, managed to regulate these radio stations only in 2007 through a public notice. Currently are about 34 stations of the genre operating only in 87.5 MHz (different from the frequencies commonly used).

On July 10, 2018, the Federal Senate Plenary approves the power increase from 25 watts to 150 watts, the effective half of a local commercial radio. The senator and author of the bill said it will improve coverage in rural areas where homes are more dispersed. However Anatel may interfere and determine the maximum power that can be transmitted, especially when there are adjacent CRs. The former minister Gilberto Kassab ordered to extinguish on the eve of 2019 more than 130 community radios for irregularities. Minas Gerais was the one that most lost emisoras (27) followed by São Paulo (20), another 22 states lost 1 CR for each one.

It is the most common type of radio broadcasting in Brazil. By 2014 there were 4641 broadcasters, 47% of all radios, being twice the commercial + educational FM and the triple of medium-wave broadcasters.

Canada

Community radio stations in Canada often target commercially underserved minority-language communities such as Franco-Ontarians, Acadians, Anglo-Quebecers or First Nations. These stations are often volunteer-run and operated by cooperatives or other not-for-profit corporations. In larger cities, community-oriented programming more commonly airs on campus radio stations, although some cities do have community radio stations as well. Most English-language community stations in Canada are members of the National Campus and Community Radio Association, or NCRA, while most of Canada's French language community radio stations are members of either the Association des radiodiffuseurs communautaires du Québec (ARCQ) or the Alliance des radios communautaires du Canada(ARC).

The province with the largest number of community radio stations in Canada is Saskatchewan. The majority of those stations are affiliated with Missinipi Broadcasting Corporation, an aboriginal public radio network. Community stations are subject to the Canadian Radio-television and Telecommunications Commission's (CRTC) community radio policy.

In this policy, the CRTC requires community stations to

  • facilitate community access to programming;
  • promote the availability of training throughout the community; and
  • provide for the ongoing training and supervision of those within the community wishing to participate in programming.

It also requires stations to offer diverse programming that reflects the needs and interests of the community, including:

  • music by new and local talent;
  • music not generally broadcast by commercial stations;
  • spoken word programming; and
  • local information.

The CRTC maintains a list of community stations. In Canada, call letters and frequencies are regulated by Industry Canada’s Spectrum Management.

The CRTC classifies community radio stations as one of two types, with slightly different regulatory requirements. Most stations are classified as "Type B"; however, a community radio station which operates as the sole local media service serving its community — such as an English language community radio station in Quebec, a First Nations radio station or a community radio station in a small town with no other local radio stations at all — is classified as "Type A", granting it a more flexible set of regulatory and license requirements to accommodate the wider range of community programming interests that such a station needs to serve.

Ecuador

In Ecuador, many community radio stations are operated by religious groups and include Catholic, Protestant and Baháʼí Faith stations. The amount of community participation and self-management varies. Radio Latacunga was associated with a project in which indigenous organizations were supplied with simple equipment to record weekly programs for broadcast in the early morning. Some indigenous groups operate their own radio stations; these include the Shuar Federation in the tropical rainforest, and the community of Simiatug in Bolívar Province. Unlike in Bolivia, trade-union radio has historically not been influential in Ecuador.

Ethiopia

Ministry of Communication and Information Technology (MCIT), Federal Republic of Ethiopia and World Development Foundation, New Delhi, India signed an agreement on 30 June 2014 for establishing seven Community Radio Stations at Finote Selam, Dilo (Borana), Adola Rede (Guji), Chewaka (Illubabor Zone|Illubabor), Semera, Ari Woreda (Debub Omo) and Uba Debretsehay (in Gamo Gofa zone, Southern Nations, Nationalities and People Region), Ethiopia to serve as an avenue for the free flow of beneficial information aimed at uplifting the plight of the various sectors of the community. The stations were planned to open up possibilities for everyone, especially regular citizens, to express themselves socially, culturally, politically and spiritually, thus preparing each and every member of the community to participate in decision-making.

World Development Foundation, with an active support of different agencies of Government of India and Embassy of India in Ethiopia and especially HE Mr. Sanjay Verma, Ambassador and Mr. Vijay Kumar, Dr. Hari Om Srivastava and MCIT, Ethiopia was able to complete the job and hand over all the Community Radio Stations to MCIT in September 2015.

CRS at Finote Salem

Milestones

  • Signing of Agreement: 30 June 2014
  • Opening of Letter of Credit: 28 October 2014
  • Dispatch of Material from India/USA/Italy/Spain: Between Dec2014 to Feb 2015.
  • Receipt of material by MCIT and handing over to WDF for installation: June 2015
  • Installation and Commissioning at seven sites by WDF and handing over to MCIT: 28 June 2015 to 5 September 2015
  • Training of Officers/operational staff: 21 September 2015 to 25 September 2015

Highlights

  • The emphasis has been on using type design for Lay Out, identical equipment and installation to ease the maintenance and procurement of spares. This will also allow the exchange of staff and development of expertise.
  • The objective for training was to provide:
  • full range of WDF accredited training on the usage of the equipment, hardware and software, programming including hands on training.
  • simplified processes for equipment maintenance by the broadcaster’s trainees in order to maintain the equipment’s good working condition
  • Programming basics and use of Community Radio Station for social, cultural, political and spiritual upliftment of people in the region
  • Two local engineers were involved all through the installation.(Grateful to MCIT, Ethiopia)

Achievements Through its regular operations the community radio shall be able to:

  • provide a development forum for the community;
  • encourage participatory community development;
  • promote active involvement of underprivileged groups such as women and young people;
  • intensify the sharing of information within the community;
  • encourage innovation in community development;
  • increase the free flow of accurate and balanced information to, and within, the community;
  • provide a forum for local cultural expression; and improve people’s access to information in local languages

The Mediaction Foundation together with the Jimma Community and the Jimma University realized the first community radio station in Ethiopia in 2007. The Community radio station is located in Jimma University (in the south-west of Ethiopia).

Guatemala

  • There are more than 100 community radio stations operating in Guatemala, but the indigenous communities don't have explicit rights to use radio frequencies, though their right to exist is guaranteed by the country's Peace Accords.
  • Many believe the lack of support for community radio puts the volunteers in a very vulnerable position, and the law puts freedom of expression at risk.

Hungary

The first community stations began as pirates, broadcasting political free-speech and music programs after the change from socialism. Tilos Rádió in 1991 was the first such station, followed by Fiksz Rádió and Civil Rádió. Since 2004 a new category arose: kisközösségi (small community stations), which are low-power stations. By 2010, more than 70 such microstations have begun broadcasting throughout the country. There are village stations, small-town stations, university stations, subcultural and religious stations. In Budapest Cool FM, Első Pesti Egyetemi Rádió and Fúzió Rádió are small community stations.

India

Union Minister for Information and Broadcasting, Mrs. Ambika Soni inaugurating the Community Radio Station, at Punjab University, in Chandigarh on February 13, 2011

In India the campaign to legitimise community radio began in the mid-1990s, soon after the Supreme Court of India ruled in its judgment of February 1995 that "airwaves are public property". The judgment inspired several free speech advocates, academics and community members across the country to being a concerted campaign to legitimize community radio in India.

In 1996, a Bangalore-based media advocacy group called VOICES organized a gathering of community radio stakeholders. A declaration calling for the establishment of a third tier of broadcasting, i.e., community broadcasting, was signed. A suggestion that AIR's local stations should allocate regular airtime for community broadcasting was put forward. Requests were also made for grant of licences to NGOs and other non-profit making groups for running community radio stations. Subsequently, UNESCO made available a portable production and transmission "briefcase radio station" kit to VOICES to do experimental broadcasts of programmes for a hands-on learning experience towards the objective of setting up an independently run community radio station.

A UNESCO sponsored workshop, hosted by an Andhra Pradesh NGO, Deccan Development Society (DDS) from July 17–20, 2000 in Hyderabad issued the 'Pastapur Initiative' on community radio that urged the government to take its intentions of freeing broadcasting from state monopoly to its logical conclusion, by making media space available not only to private players but also to communities. This landmark document urged the government to create a three-tier structure of broadcasting in India by adding non-profit community radio to the already existing state-owned public radio and private commercial radio.

Simultaneously, several initiatives had already started working on community radio in terms of production and dissemination of participatory programming. In South India, Deccan Development Society worked with Dalit women's collectives to start Sangam Radio, the programmes for which were made by the community, but were 'narrowcast', i.e. played back to the community over cassette players at group meetings. Another landmark initiative was jointly set up by VOICES and MYRADA - called Namma Dhwani (Our Voices), where programmes were produced by communities in and around the village of Budikote (about 100 kilometers from Bangalore), and were distributed over the nearest All India Radio station and subsequently over the local cable network. In the west, Kutch Mahila Vikas Sanghatan, a civil society group in Gujarat worked with the women in Kutch District to produce programmes on local developmental and cultural issues, and started broadcasting on the nearest All India Radio Station. In the northern part, Alternative for India Development made programmes with community members in Garhwa block of Jharkhand, and broadcast programmes over the Daltonganj All India Radio Station. Community Groups in Chamba, and Rudraprayag, both in Uttarakhand started producing participatory programmes and broadcast over the World Space Satellite Radio network. Kumaon Vani radio station was set up by The Energy and Resources Institute in March 2010 in Nainital district of Uttarakhand with the aim of bringing together communities across several villages in the Kumaon region. It was established to use radio as a tool to promote sustainable development among the local farming community. It broadcasts content that is relevant to the people of the area that is overlooked by commercial media.

By early 2003, the government of India released the first set of community radio guidelines drafted by Dr. Hari Om Srivastava and also the technology to be used, but unfortunately, restricted eligibility to educational institutions only. Marginalized and voiceless communities continued to remain outside the ambit of the then released community radio policy guidelines. Anna FM was India's first campus "community" radio station. And, as per the latest Community Radio Policy Guidelines (2006), Anna FM falls well within the definition of Community Radio. Launched on 1 February 2004, it is run by the Education and Multimedia Research Centre (EM²RC). Programmes are produced by students as well as community. Anna university station was launched on 1 February 2004 . Commonwealth of learning and UNESCO sponsored an international meet on community radio at Anna university in December 2004 . All the applicants to CR in India as well as representatives from 13 countries attended. Government of India studied the working of this station along with the change of ruling party in India Several of the lessons learnt at Anna CR were incorporated in the Policy document in 2006. Practitioners and community radio advocates continued to push the government towards expanding the mandate of the community radio sector to include communities living in rural, remote and hilly areas of the country.

On 16 November 2006, the government of India implemented new Community Radio Guidelines, which permit NGOs, educational institutions and agricultural institutions to own and operate community radio stations. By 30 November 2008, there were 38 operational community radio stations in the country. Of these, two are run by NGOs and the rest by educational institutions.

The first community-based radio station licensed to an NGO (as distinct from campus-based radio) was launched on 15 October 2008, when Sangham Radio, licensed to Deccan Development Society, in Pastapur village, Medak district, Andhra Pradesh state went on the air at 11:00 am. Therefore, Sangham Radio, based on the policy guidelines, is second community radio station of India. Sangham Radio, which broadcasts on 90.4 MHz, is licensed to the Deccan Development Society (DDS) (an NGO which works with women's groups in approximately 75 villages in Andhra Pradesh). The community radio station is managed by "General" Narsamma and Algole Narsamma.

Under the 2006 community radio policy, any not-for-profit "legal entity"—except individuals, political parties (and their affiliates), criminal and banned organizations—can apply for a CR license. The licence entitles them to operate a 100-watt (Effective Radiated Power) radio station, with a coverage area of approximately a 12-km radius. A maximum antenna height of 30 meters is allowed. Community radio stations are expected to produce at least 50 percent of their programmes locally, as much as possible in the local language or dialect. The stress is on developmental programming, although there is no explicit ban on entertainment. News programmes are banned on community radio in India (as they are on commercial FM radio). However, the government has clarified that certain categories of news are permitted on radio, including sports news and commentaries, information on traffic and weather conditions, coverage of cultural events and festivals, information on academic events, public announcements pertaining to utilities such as electricity and the water supply, disaster warnings and health alerts. Five minutes of advertising per hour is allowed on community radio. Sponsored programs are not allowed, except when the program is sponsored by the government at the local or state level.

In a given license area, the Wireless Planning and Coordination (WPC) wing of the MoCIT reserves only three frequencies for community radio. This reservation is informally done and the WPC does not have any official communication or guidelines with respect to spectrum allocation for community radio in the FM band. The WPC follows a channel separation of 800 kHz in India. This means that if a radio station is allotted 90.4 MHz in a given license area, then the next available frequency is 91.2 MHz. Further, once a radio station is allotted a frequency by the WPC, that particular frequency is blocked for a radius of 100 kilometers.

Activists and community workers from across the country have banded together under the aegis of the Community Radio Forum of India to coordinate training and support for community radio stations, and to work for a more proactive community radio policy. The Community Radio Forum, India, was registered as a Society and Trust on 26 February 2008. Members from the Community Radio Forum participate in screening committee meetings to screen potential applicants, and the organization is also recognized as a national level self-regulatory body in the Draft Broadcast Bill as published by the Government of India.

By 1 July 2010, the Ministry of Information and Broadcasting announced that 715 applications for CR licenses had been received, including 104 under the old campus-radio guidelines. 231 Letters of Intent were issued (including 63 under the old guidelines). Grant of Permission Agreements were signed with 102 applicants, and 68 community radio stations were on the air. 107 applications were rejected, and 377 applications were being processed. By 1 February 2012, the Ministry of Information and Broadcasting had received a total of 991 community radio licence applications. Grant of Permission Agreements had been signed with 161 applicants and 126 community radio stations were on air.

From April 1, 2012, the Ministry of Communications and IT has hiked the spectrum fees to Rs. 91,000 - a fivefold increase from the previous annual fee of Rs. 19,700. This move provoked widespread protest from functional community radio stations, advocacy bodies like Community Radio Forum and Community Radio Association of India, and even the Secretary, Ministry of Information and Broadcast has gone on record to say that his Ministry's views were not sought before the decision was taken. He also expressed concern that many organizations would find it impossible to pay the increased spectrum royalty charges. The Community Radio Forum has already boycotted one policy consultation held by the Ministry of Information and Broadcasting, on 9th and 10 May. Several community radio stations also observed a 'Day of Silence' on 9 May, where the spectrum fee hike was announced, protest songs were broadcast, community views were invited, and transmission was switched off for the rest of the day. After pressure from various stakeholders, the Ministry for Information and Communication Technology (MoCIT) announced that the spectrum fee and royalty charges would be rolled back to annual fee of Rs. 19,700. The spectrum fee was Rs. 19,700 annually, till September 2013, at which time the Ministry was to re-examine the matter.

According to the Ministry of Information and Broadcasting, Government of India, the status on 25 April 2013 of Community Radio in India was:

  • No. of applications received so far, from 2004 to 05 Feb 2013 (including 104 under 2002 CR Guidelines): 1200
  • Letters of Intent (LOI) issued: 428
  • Grant of Permission of Agreement (GOPA) signed: 191
  • Operational Community Radio Stations: 148
  • Number of applications rejected: 545
  • Applications under process: 227

The complete list of operational community radio stations in India is published on the website of the Ministry of Information and Broadcasting. Additionally, Jose Jacob, of the National Institute of Amateur Radio in Hyderabad has also published a list of available stations.

To see details and descriptions on each of the individual operational community radio stations, the Ministry of Information and Broadcasting prepares a compendium on Community radio, which is also available and published on their website.

Community Radio and Commonwealth Educational Media Centre for Asia (CEMCA): from 2007 onwards, with CEMCA being the implementing agency and DR R Sreedher as its director, the Ministry of Information and Broadcasting, Government of India organized more than 40 awareness workshops throughout the country to create an atmosphere for getting more organisations to apply for a license for CR. By June 2012, the government had received more than one thousand applications and 400 of them got the Letters of intent LOI. While the initial phase saw more stations in educational campuses an analysis of the 400 LOIs brings out the fact that two thirds of the LOIs have gone to civil society organisations. They find it difficult to launch the station, due to lack of funds, training, human resources and the difficulty in getting the frequency cleared by the WPC wing of the Ministry of Telecommunications. In July 2014, Government of India announced a scheme to support community radio stations and allocated 100 crore for this purpose.

Community Radio Association Community Radio Association was formed soon after the first Sammelan of CR stations in 2011 in Delhi. 58 stations expressed their interest in April 2011 for the formation of an association, wherein people working on the ground, can represent their communities and bring the voices of the voiceless to the fore. A paper was prepared and circulated among operational stations and a consensus on the role of the association, its structure, objectives etc. were arrived at. A society was registered in Delhi in July 2011, under the Societies Registration Act.

The salient features of the CRA are:

  • Only representatives of functional CR stations are its voting members
  • It has been registered as an All India Body with 12 members from nine different states signing the MOA
  • CRA works in a decentralized manner with Zonal and State Chapters. Each Chapter is empowered to organize workshops, events in line with CRA’s objectives.

Even though CRA is only two years old its contribution and the role of its members in building an environment in favour of community Radio has been substantive.

CRA has been organizing events/workshops and has been sharing the experiences of its members across the globe. Some of its members have been representing the movement in international forums and reiterating the power of the Community radio. They have been supporting the growth of this movement in countries of both Europe and Africa.

Since CRA is a member-based organisation, all its members have been running community radio stations, in diverse regions and dialects, together they bring to the table a mine of resources and experience.

The strength of CRA is its network of experienced radio practitioners, who manifest the mandate of the Community Radio. This organisation is a true reflection of India’s diversity, the multitude of languages and dialects, the varied topography and history. It is the only network in this sector, which is totally democratic and allows space for dissent, as there is nothing homogeneous about any community.

If we try to total up the experience of each member radio station- which are now 92 in all, then it would amount to a huge figure. The reach of this radio station together is to over 4 million people.

In 2013, CRA has organized two zonal workshops – South and West Zones and three state level experience sharing meets – Tamil Nadu, Maharashtra, Kerala. There have been workshops and meetings in all the zones, wherein members have come together and shared their challenges and achievements.

With a mission to promote, encourage, support and facilitate all functional and desirous Community Radio Stations in India and abroad, CRA has already hosted seven workshops for the Ministry of Information and Broadcasting. The seven Community Radio Awareness workshops were held at Dibrugarh, Ooty, Goa, Faridabad, Bhubaneswar, Kochi and Jaipur. The participation of the desirous Community Radio Operators was tremendous. The quality and content of the workshops was well thought out, and inspiring. Over 90 percent of the participants gave Letters of Intent on the last day.

CRA led the entire campaign against the rise in the licence fee. Members of the organisation met with the Minister, Mr Kapil Sibbal, personally and handed over the petition that was signed by all its members. CRA worked closely with CRF on this issue, and also organised a meeting with the then Minister of Information and Broadcasting, Ms Ambika Soni, who took up the issue of the hike in fees with the concerned department. Besides this:

  • Members of CRA, have been part of the working paper on the Community Radio Support Fund, and contributed extensively to the process.
  • CRA members are part of the screening committee for new stations.
  • CRA Members are also part of the Technical committee for Community Radio Support Scheme (CRSS) and their suggestions and inputs have been considered valuable.
  • CRA members were also the pioneers in developing a proposal for the incorporation of a Community Radio Peer Review to strengthen and support the operations of already existing community radio stations through cross learning and sharing. CRA member are also involved in the CR Policy review discussions.
  • Individual members of CRA have worked in various capacities as facilitators, mentors, trainers for other organizations involved in the CR space namely, CEMCA, Ministry of Science and Technology, UNESCO.
  • CRA is working on different training modules for capacity building in CR and disaster management, sustainability, knowledge sharing, mobilizing communities for health care, collaboration on non-formal learning and education programmes.
  • CRA member stations have also won awards for their work in integrating technology with Community Radio and several ongoing research are being conducted on the same
  • CRA member stations have been invited as speakers to several national and international forums like Bangladesh Community Radio Forum (25–27 February 2012), Asia-Pacific Institute for Broadcasting Development (AIBD) 2012, Asia Media Summit (29 May 2012), Cyprus Community Media Center, Nocosia (January 28, 2013, Radiodays Europe radio conference in Berlin 18–19 March 2013, International Association of Women in Radio and Television, seminar on Community Radio and Democracy in South Asia (5 March 2013)

Content Exchange and Knowledge Sharing for community radio

Indian government has been promoting content exchange especially radio programmes, good practices, case studies etc. to facilitate meaningful utilisation of available resources.

In past two years, Ministry of Information and Broadcasting has promoted EK duniya anEK awaaz (Edaa) - which is an audio and knowledge exchange portal for Community Radio practitioners in South Asia. Launched in year 2008, Edaa is completing 5 years on 1 September 2013.

Edaa is a web-based service that uploads the content of radio stations. Listening to Bhojpuri or Tamil from villages that don't appear even on Google maps, is such an exciting platform that even the ministry mentions this in its press release on future plans for Community Radio. Edaa is South Asia's biggest community-produced audio bank and hosts more than 2,900 radio programmes in 28 different South Asian languages categorised under 33 thematic areas. Another online space that supports learning and knowledge exchange between Community Radio stations in India is the Community Media Manch Platform  This platform supports collaborations, knowledge sharing and webinars that community radio stations and members of community media can undertake to share their experiences.

Ireland

Ireland has had self-described community radio stations since the late 1970s, although it was not until 1995 that the first 11 licensed stations went on the air as part of an 18-month pilot project run by the Independent Radio and Television Commission. Early stations were represented by the National Association of Community-Radio Broadcasters, which in 1988 published a guide to setting up new stations.

There are 24 licensed stations in Ireland. In 2004 the licensed stations formed a co-operative CRAOL as a representative group in 2004, with the stations as shareholders. In 2007, new membership categories were created for aspiring stations, and a "Development Ladder" established to aid new stations in their development. By 2010, there were 42 aspiring stations at various stages of development. The Broadcasting Act 2009 provided a legal definition of community radio, which previously had been determined by the Community Radio Policy of the Broadcasting Commission of Ireland (now the Broadcasting Authority of Ireland). The Act also provided for the availability of a 100-day licence (within a 12-month period) for aspiring groups who meet the legal definition.

An Agreement for Mutual Co-operation was established in 2008 by CRAOL; this ensures that the signatories (which include all fully licensed stations) share successful funding applications, training materials and policies. This has led to a significant increase in networking and information-sharing. The agreement also covered the sharing of programming, and a network website facilitates these activities through a resource bank and online programme exchange.

Community radio stations in Ireland encompass stations serving a geographic community or a community of interest (such as campus stations, Christian and Irish-language stations). Accredited training in Community Radio has been available through CRAOL since 2004. The pace of such training has increased since mid-2009, with 95 percent of CRAOL member stations involved. In June 2010 the first Community Radio Conference was held in Croke Park, Dublin. Stations are located in all four provinces of Ireland; however, coverage is not universal. Dublin has the largest number of stations, and there are significant clusters in north and west Connaught and mid-Munster.

Community radio in Ireland encompasses:

  • Process: Participation by communities in creation of programming
  • Product: Service provided to the community through programming supplied

The combination of process and product is determined by the needs of the community, and implemented through a management structure controlled by the community.

Japan

Japan has a network of low-power community radio stations across the country. Their most common call sign is JOZZ-XXX-FM.

It was institutionalized in 1992. 1995 Great Hanshin earthquake and later, the number of broadcasting stations has increased. Currently (September 2015), about 300 stations exist.

Jordan

The first community radio AmmanNet.net was established in 2000 in Jordan on the internet by award-winning Arab journalist Daoud Kuttab as a means of bypassing government restrictions on private, non-governmental radio. In 2005 AmmanNet was licensed as an FM private station in Jordan's capital, Amman. The radio paid US$30,000 for a licence. AmmanNet has also been involved in the training of two other community radio stations in Jordan: one in the twin villages of Lib and Mleih, and another as part of King Hussein University in the southern city of Ma'an. AmmanNet is also involved in training Arab media activists in internet radio. A program was begun to train personnel and launch nine Gulf-based radio stations as part of khaleejnet.net. In January 2008, the name of AmmanNet radio was changed to Al-Balad radio while AmmanNet.net remained as a news website.

Two other community radio stations have been established in Jordan. Yarmouk FM is located at Yarmouk University in Irbed as part of the school's Journalism and Mass Communications program. Farah FM is under construction, but has a license to broadcast in Amman and Zarqa (Jordan's second-largest city). This station will focus primarily on youth and women's issues.

Philippines

The best-known community radio network in the Philippines is Radyo Natin (Our Radio). Its stations nationwide broadcast a live Manila feed via satellite; sometimes stations air local programming, cutting the Manila feed. It is considered a community network, because local programs air on different RN stations. Radyo Natin is owned by the Manila Broadcasting Company.

Radyo Natin is the largest network of community radio stations in the Philippines, counting over 150 small FM stations throughout the archipelago from Batanes in the north to Tawi-Tawi in the south. RN stations are owned and operated by franchise holders, who are public-service-oriented communicators in their own right. With audio streaming, it is possible for the national feed to reach listeners all over the world via the internet; it is hoped that in the near future (as of 2011), the franchise stations will also be heard worldwide. Radyo Natin is able to reach audiences that have never been reached before by radio.

Although Radyo Natin is found in the FM band, in the mornings it affiliates with Manila Broadcasting Company’s flagship station, DZRH, for national news programming. During the afternoons, Radyo Natin features popular music.

With its studios at the MBC Building in the Star City Complex in Pasay, Radyo Natin sends its signals to its stations by satellite. These stations, in turn, rebroadcast its signals locally. These individual Radyo Natin stations can, however, "unhook" from the Manila central studios and air events in their own areas at specified times; thus, Radyo Natin is nationwide in coverage but local in nature.

In 2005 a show-cause order containing a cease-and-desist directive from the commissioner of the National Telecommunications Commission was issued to Radyo Natin, forcing the closure of all stations. In the order against Manila Broadcasting Company, NTC Commissioner Ronald Olivar Solis said that the company is "operating a low power FM station as a commercial broadcasting station without the necessary authority from the Commission."

Nepal

Radio Chapakot, a community radio of Nepal

Nepal adopted community radio in 1997 when Radio Sagarmatha (Sagarmatha is the Nepalese name for "Mount Everest"), broadcasting on 102.4 MHz, became the first independent public-interest broadcaster in South Asia. It was established by the Nepal Forum of Environmental Journalists (NEFEJ) in May of that year. Radio Sagarmatha is in the front lines of the fights for freedom of expression and the right to information of Nepalese citizens.

As of 2011, there are more than 150 community radio stations which have been licensed by the Nepalese government. In Nepal, there are no separate policies or laws for community radio. The existing policy and applies to both community and commercial radio stations. Community radio stations have been petitioning the government to introduce different policy and law for community radio stations, whose mottoes are social change and social justice. They have played a role in restoring democracy and changing Nepal to a republic from a monarchy. The rule of law, gender equality, education, health, civics, anti-corruption initiatives, good governance, the environment and day-to-day problems and issues are examined in a different format by the local community radio stations. Community radio enjoys good coverage throughout Nepal, and news is one of its most popular formats. Its first Radio Producer/presenter was Mr. Ghamaraj Luitel, who served Radio Sagarmatha holding different positions in programme and top management for nearly one and one-half decades. He made Radio Sagarmatha very popular through unique radio programmes among its listeners during his 15 years service and left it after playing vital role to develop it as Station Manager for four years. Mr. Luitel led Radio Sagarmatha during the King Gyanendra's coup to save independent radio movement playing a role as central spokesperson after February 1, 2005.

Radio Sagarmatha's history is interwoven with the gradual loosening of government control over the airwaves in Nepal. From the time of the new constitution in November 1990, the drive to put the station on the air was instrumental in bringing about a new communications environment and a new awareness of the importance and need for independent, public-interest broadcasting.

Mass media in Nepal face barriers; the geography of the country is ill-suited to either mass-circulation print media or coverage by electronic media. Access to newspapers, radio, television and education is limited by poverty; Nepal has a low literacy level, particularly in rural areas and among women. Both print and electronic media are concentrated in urban centers like Kathmandu and are thought to have limited relevance for rural people.

In 1990, Nepal changed from a monarchical non-party system to a parliamentary model. A new constitution enshrined the right to freedom of expression (specifically, the right of every citizen to demand and receive information on any matter of public importance). The expression of basic communication rights in the constitution was followed by more focused policy and practical guidelines: in 1992, a National Communications Policy; in 1993, a National Broadcasting Act and in 1995, broadcast regulations.

Before 1994 radio broadcasting was the exclusive domain of Radio Nepal, the state broadcaster established during the early 1950s. Even after 1990, state governments were slow in relinquishing monopoly control of radio broadcasting. The first independent license was granted in 1997, four-and-a-half years after the initial application. The battle for this license was long, hard-fought and significant. The main obstacles were an unstable political environment, conservative politicians and bureaucrats disinclined to change and the monolithic presence of Radio Nepal. Between October 1992 (when the application was registered) and May 1997 (when the license was granted), Nepal had four different governments, four ministers and four secretaries of communication. Waged primarily by journalists committed to the cause of free expression and public-interest broadcasting, the fight involved figures of national prominence, professional associations, NGOs, the print media, foreign embassies, UN organizations, and INGOs.

From the outset the main organization vehicle for Radio Sagarmatha (for both the campaign to get a license and to establish a radio station) has been the Nepal Forum of Environmental Journalists, a non-governmental organization and association of journalists. Key international supporters during the establishment phase were UNESCO and DANIDA.

NEFEJ is the current license-holder of Radio Sagarmatha, although the station was officially a joint effort and partnership with three other media-based NGOs: the Himal Association, Worldview Nepal and the Nepal Press Institute. The station was headed by a seven-member board of directors, constituted by NEFEJ. Through NEFEJ bylaws, the board had representation from all four partner NGOs and met monthly to review and plan activities, set policy and provide direction for the station.

In April 1999, Radio Sagarmatha operated with the following staff: a station manager, six full-time producers, two technicians, a music librarian, an engineer, an accountant and an assistant. The station also benefited from the contributions and experience of international supporters. Volunteers are an important part of Radio Sagarmatha's programming and operation. The station's programming has given many people the opportunity to have their voices and opinions heard in a public forum. On a daily basis, the station takes listeners into everyday life. The variety of voices and sounds (and its less-than-state-of-the-art equipment) gives the station a different tone from other broadcasters in the region: one of real life, as lived and programmed by real people. Interviewees and those profiled on the station come from a variety of backgrounds and occupations.

Radio Sagarmatha works to present listeners with "a human package": a combination of issues and entertainment, social discussions and music, and a conduit for the variety of voices and opinion previously unheard on Nepal's radio channels. In its programming, the station's difference from the state broadcaster and the growing number of Western-style commercial stations is most evident. Public-affairs journalism and broadcasting are at the heart of Radio Sagarmatha's mission and vision for a more responsible press and a more pluralistic society. With a long tradition of folk media and a rich musical heritage, cultural programming is also prominent in the station's six-hour daily broadcast.

Other aspects of programming include an initiative named "Safa Radio: The Clean Air Campaign" in which the station works with the Nepal Environmental Scientific Society to measure air pollution in Kathmandu and broadcasts information about the capital's air quality. Though prohibited at first from broadcasting news, the station airs summaries of daily news stories in a format mixed with music and broadcasts daily community-news programs. Community access is an important part of programming. There is a daily feature, It's My Turn Now (in which individuals from the community voice their opinions), vox populi segments, listeners' letters and feedback recorded by telephone. In late 1998, Radio Sagarmatha formed a partnership with the BBC World Service; 30 minutes of the BBC Nepali service and 30 minutes of world news in English are heard in, respectively, the evening and morning programme blocks. A full list of stations can be found on the website of the Association of Community Radio Broadcasters Nepal.

New Zealand

The Association of Community Access Broadcasters (ACAB) is a group of 11 New Zealand community radio stations. The stations, established between 1981 and 2000 and receiving government funding since 1989, broadcast community programming and provide facilities, training and on-air time for individuals and community groups to produce the programming.

The ACAB group is a core component of New Zealand On Air's Community Broadcasting Strategy. A government funding pool of approximately $2 million is allocated annually for the 11 stations to produce programming for women, youth, children, ethnic and other minorities and people with disabilities in accordance with section 36(c) of the Broadcasting Act 1989. Individual station funding is allocated on a four-tier system based on audience reach, with each station receiving between $110,000 and $220,000. In return for government funding, ACAB stations have an individual and collective mandate to broadcast programmes for people of a wide range of particular religions, cultures, languages, ages and sexualities. Stations operate independently and locally, making decisions on programming and scheduling by consensus.

South Africa

Shortly after the end of World War II, the country's repressive state policies gave the SABC (South African Broadcasting Corporation) an effective monopoly. For nearly half a century it was the only broadcaster permitted to operate, and faced no independent radio competition on South African territory until the early 1990s' transition to democracy. The first legally permitted, non-SABC broadcast was that of 1991's "Festival Radio" from the campus radio studios at Rhodes University in Grahamstown. An Independent Broadcast Authority was created to oversee the opening of the country's airwaves, with small community radio stations being permitted to broadcast for the first time. Applications were discussed in open session, to ensure transparency and accountability. Notable early community broadcasters included Bush Radio in Cape Town and Radio Unitra in Umtata. The Independent Communications Authority (ICASA) now regulates (as of 2011) the telecommunications and broadcasting sectors.

Solomon Islands

The Solomon Islands have a number of community FM radio stations established under a United Nations Development Programme in Isabel Province. In March–June 2009 these were used to strengthen women and youth networking under a peace-building project of the Commonwealth of Learning. The stations are linked to rural email stations of the People First Network. The Don Bosco Technical School has also assisted the Tetere community in operating a radio station near Honiara, and the Solomon Islands Development Trust established a Community Media Centre to expand local capacity.

Soweto has only 1 Community Radio Station called Jozi Fm 105.80 FM. It first went on air in 1995 as Bua Community Station and it was later named Jozi Fm. It is now led by Mr Mpho Mhlongo who is a former presenter and one of the founders of the station.

South Korea

The South Korean government licensed several low-power community radio stations in 2005. Maximum power is one watt, which covers 5 km.

Sweden

In Sweden, community radio (Swedish: närradio) was introduced in 1978 with test transmissions; regular broadcasts began the following year. Commercials were not permitted until 1993, but stations are primarily operated as non-profit NGOs. There are 150 community radio stations in the country.

Syria

ARTA FM is the first community radio station in Syria broadcasting in three languages: Kurdish, Syriac and Arabic. It was established on 07.06.2013 in Amudah and it has offices in Amudah and Qamishli in Syria.

Thailand

Community radio in Thailand grew quickly during the government of Prime Minister Thaksin Shinawatra, taking advantage of a delay in the establishment of a regulatory authority. Thailand's 2,000 to 3,000 community radio stations (often operating unlicensed) have been accused of causing interference with air-traffic-control and other radio stations. However, selected community radio stations have been the target of police crackdowns, causing critics to accuse the government of political interference.

United Kingdom

In the UK, the idea of community-based services can be traced back at least as far as the original concept for BBC local radio in the early 1960s. Thereafter, various land-based unlicensed pirate radio stations (such as East London Radio and Radio AMY: Alternative Media for You) developed the idea further. As pirate stations proliferated during the late 1970s and early 1980s, these stations were joined by those broadcasting specifically to minority immigrant communities (such as the Afro-Caribbean and Asian communities, particularly in cities such as London, Birmingham, Bristol, Gloucester and Manchester). Although "community radio" remains synonymous with "pirate radio" for some people in the UK, most minority immigrant stations focused purely on specific musical genres and were operated (theoretically at least) on a for-profit basis. Community radio services in the UK are operated on a not-for-profit basis, with community ownership and control built into their structure.

Community radio stations were in operation on cable systems from 1978 onwards; mostly situated in new-town areas, they were operated by volunteers. Notable stations included Radio Thamesmead (later RTM Radio) in southeast London, one of the first cable radio stations in the UK, which began on the Rediffusion cable system in the southeast London area in 1978. During the late 1980s and early 1990s, the newly formed Radio Authority awarded licences (termed "Incremental" by the outgoing Independent Broadcasting Authority) to a number of new, ex-pirate and cable-based community ventures. The old breed of community radio stations could raise funds by selling airtime and by receiving donations or grants.

Following an experiment of Access Radio licensed by the former UK broadcast regulator the Radio Authority, legislation was brought to create a new tier of community radio regulated by the RA's successor OFCOM. The first station to go on air under this new scheme was 103 The Eye which launched on 1 November 2005, serving the Vale of Belvoir on the Leicestershire/Nottinghamshire border on 103 FM and on the internet. Since 2005 some 300 such stations have been licensed by broadcasting regulator Ofcom operating on five-year licences with the opportunity to renew at the end of each term. Most community radio stations in the UK are on FM, typically at a power of 25 watts. FM community radio stations include Andover Radio, Cambridge 105, Chiltern Voice FM, Preston FM and Penistone FM. A few community radio stations broadcast on AM (medium wave), particularly in rural areas, and some operate online, like Windmill Broadcasting, the UK's only radio station broadcasting from a Windmill, in the Broad Eye Windmill, Stafford.

With the introduction of SS-DAB (small-scale Digital Audio Broadcasting licences) from Ofcom, a new breed of community radio stations will launch on DAB in towns and cities around the UK. Stations, such as Blyth's South Beach Radio are piloting their formats with web streams in preparation for a DAB launch when the licences become available.

United States

In the U.S., community radio stations are non-profit, community-based operations licensed by the Federal Communications Commission. These stations differ from other public radio outlets in the U.S. by allowing community volunteers to actively participate as broadcasters.

In the U.S., community radio stations generally have smaller budgets than National Public Radio (NPR) network outlets, due to the smaller audiences attracted by their diversified programming and in turn, the small number of potential contributors and business supporters. Community stations are distinct from NPR stations in that most community-radio programming is locally produced by non-professional disc jockeys and producers, whereas traditional public stations rely on programming from NPR and other outlets (such as PRI). However, some community stations, such as KVNF in Colorado and WDIY in Pennsylvania, carry NPR in addition to their volunteer-based local origination programming.

Parade at the launch of WXOJ-LP, Valley Free Radio, in Northampton, Massachusetts in August 2005

Many community stations are licensed as full-power FM stations, while others, particularly those founded after 2005, are licensed under low-power broadcasting rules. Many of the former were founded in the 1960s and 1970s when cultural experimentation (such as the New Left) in the U.S. had a significant following, while others were influenced by the philosophy of radio activist Lorenzo Milam. Community radio stations are usually overseen by non-profit organizations, which are led boards of directors and often include paid staff for managing business operations and coordinating volunteers. Community radio programming involving volunteers is also offered as part of student-run stations at colleges, universities and in some cases, high schools.

The National Federation of Community Broadcasters was formed in 1975 as a membership organization for community radio stations. NFCB publishes handbooks for stations, hosts an annual conference and lobbies on behalf of community radio at the federal level. It was criticized in the 1990s for perceptions it advocated homogenization of programming. The organization has changed leadership since this period. The Grassroots Radio Coalition is a loose network of stations which formed as a reaction against increasing commercialization of public radio and lack of support for volunteer-based stations.

UNESCO

UNESCO is a strong supporter of community radio and works to increase the viability of local radio stations around the world. In 2001, the Media Development and Society Section produced the “Community Radio Handbook” to share best practices collected through the Organization’s involvement in the sector. This handbook specifically gives recommendations to radio station personnel in how to engage listeners in democratic debate as a means to forward community development.

The Organization has also supported community radio through the direct training of radio station staff. The “Empowering Local Radio with ICTs” project strengthened the reporting capacities of 59 local radio stations from 2012 to 2018. This UNESCO project was implemented in 10 countries of Sub-Saharan Africa, including Burundi, the Democratic Republic of the Congo, Kenya, Lesotho, Namibia, Rwanda, South Africa, Tanzania, Uganda and Zambia. Workshops focused on improving the quality of broadcasts, building widespread correspondent networks and promoting sustainability.

Gender sensitivity training was another important aspect of the project, with many of the best stories pertaining to gender issues being amalgamated in the “On air with rural women” exhibition, opening the celebrations for International Women’s Day 2018 and being showcased at the 2018 European Development Days.

International

The worldwide association for free radios is the World Association of Community Radio Broadcasters (AMARC).

Friday, July 22, 2022

Animal echolocation

From Wikipedia, the free encyclopedia
 
The depiction of the ultrasound signals emitted by a bat, and the echo from a nearby object

Echolocation, also called bio sonar, is a biological sonar used by several animal species. Echolocating animals emit calls out to the environment and listen to the echoes of those calls that return from various objects near them. They use these echoes to locate and identify the objects. Echolocation is used for navigation, foraging, and hunting in various environments.

Echolocating animals include some mammals (most notably Laurasiatheria) and a few birds. Especially some bat species and odontocetes (toothed whales and dolphins), but also in simpler forms in other groups such as shrews, and two cave dwelling bird groups, the so-called cave swiftlets in the genus Aerodramus (formerly Collocalia) and the unrelated Oilbird Steatornis caripensis.

Early research

The term echolocation was coined in 1938 by the American zoologist Donald Griffin, who, with Robert Galambos, first demonstrated the phenomenon in bats. As Griffin described in his book, the 18th century Italian scientist Lazzaro Spallanzani had, by means of a series of elaborate experiments, concluded that when bats fly at night, they rely on some sense besides vision, but he did not discover that the other sense was hearing. The Swiss physician and naturalist Louis Jurine repeated Spallanzani's experiments (using different species of bat), and concluded that when bats hunt at night, they rely on hearing. In 1908, Walter Louis Hahn confirmed Spallanzani's and Jurine's findings.

In 1912, the inventor Hiram Maxim independently proposed that bats used sound below the human auditory range to avoid obstacles. In 1920, the English physiologist Hamilton Hartridge correctly proposed instead that bats used frequencies above the range of human hearing.

Echolocation in odontocetes (toothed whales) was not properly described until two decades after Griffin and Galambos' work, by Schevill and McBride in 1956. However, in 1953, Jacques Yves Cousteau suggested in his first book, The Silent World, that porpoises had something like sonar, judging by their navigational abilities.

Principle

Echolocation is the same as active sonar, using sounds made by the animal itself. Ranging is done by measuring the time delay between the animal's own sound emission and any echoes that return from the environment. The relative intensity of sound received at each ear as well as the time delay between arrival at the two ears provide information about the horizontal angle (azimuth) from which the reflected sound waves arrive.

Unlike some human-made sonars that rely on many extremely narrow beams and many receivers to localize a target (multibeam sonar), animal echolocation has only one transmitter and two receivers (the ears) positioned slightly apart. The echoes returning to the ears arrive at different times and at different intensities, depending on the position of the object generating the echoes. The time and loudness differences are used by the animals to perceive distance and direction. With echolocation, the bat or other animal can see not only where it is going but also how big another animal is, what kind of animal it is, and other features.

At the most basic level, echolocation is based on the neural anatomy of auditory brain circuitry. In essence, ascending brain pathways in the brain stem allow the brain to calculate the difference between the two ears to very small fractions of a second.

Bats

Spectrogram of Pipistrellus pipistrellus bat vocalizations during prey approach. The recording covers a total of 1.1 seconds; lower main frequency ca. 45 kHz (as typical for a common pipistrelle). About 150 milliseconds before final contact time between and duration of calls are becoming much shorter ("feeding buzz"). 

Corresponding audio file: 0:23

Echolocating bats use echolocation to navigate and forage, often in total darkness. They generally emerge from their roosts in caves, attics, or trees at dusk and hunt for insects into the night. Using echolocation, bats can determine how far away an object is, the object's size, shape and density, and the direction (if any) that an object is moving. Their use of echolocation, along with powered flight, allows them to occupy a niche where there are often many insects (that come out at night since there are fewer predators then), less competition for food, and fewer species that may prey on the bats themselves.

Echolocating bats generate ultrasound via the larynx and emit the sound through the open mouth or, much more rarely, the nose. The latter is most pronounced in the horseshoe bats (Rhinolophus spp.). Bat echolocation calls range in frequency from 14,000 to well over 100,000 Hz, mostly beyond the range of the human ear (typical human hearing range is considered to be from 20 Hz to 20,000 Hz). Bats may estimate the elevation of targets by interpreting the interference patterns caused by the echoes reflecting from the tragus, a flap of skin in the external ear.

There are two hypotheses about the evolution of echolocation in bats. The first suggests that laryngeal echolocation evolved twice, or more, in Chiroptera, at least once in the Yangochiroptera and at least once in the horseshoe bats (Rhinolophidae). The second proposes that laryngeal echolocation had a single origin in Chiroptera, was subsequently lost in the family Pteropodidae. Later, the genus Rousettus in the Pteropodidae family developed a different mechanism of echolocation using a system of tongue-clicking.

Individual bat species echolocate within specific frequency ranges that suit their environment and prey types. This has sometimes been used by researchers to identify bats flying in an area simply by recording their calls with ultrasonic recorders known as "bat detectors". However echolocation calls are not always species specific and some bats overlap in the type of calls they use so recordings of echolocation calls cannot be used to identify all bats. In recent years researchers in several countries have developed "bat call libraries" that contain recordings of local bat species that have been identified known as "reference calls" to assist with identification.

Since the 1970s there has been an ongoing controversy among researchers as to whether bats use a form of processing known from radar termed coherent cross-correlation. Coherence means that the phase of the echolocation signals is used by the bats, while cross-correlation just implies that the outgoing signal is compared with the returning echoes in a running process. Today most – but not all – researchers believe that they use cross-correlation, but in an incoherent form, termed a filter bank receiver.

When searching for prey they produce sounds at a low rate (10–20 clicks/second). During the search phase the sound emission is coupled to respiration, which is again coupled to the wingbeat. This coupling appears to dramatically conserve energy as there is little to no additional energetic cost of echolocation to flying bats. After detecting a potential prey item, echolocating bats increase the rate of pulses, ending with the terminal buzz, at rates as high as 200 clicks/second. During approach to a detected target, the duration of the sounds is gradually decreased, as is the energy of the sound.

Calls and ecology

Echolocating bats occupy a diverse set of ecological conditions ; they can be found living in environments as different as Europe and Madagascar, and hunting for food sources as different as insects, frogs, nectar, fruit, and blood. Additionally, the characteristics of an echolocation call are adapted to the particular environment, hunting behavior, and food source of the particular bat. However, this adaptation of echolocation calls to ecological factors is constrained by the phylogenetic relationship of the bats, leading to a process known as descent with modification, and resulting in the diversity of the Chiroptera today.

Flying insects are a common source of food for echolocating bats and some insects (moths in particular) can hear the calls of predatory bats. There is evidence that moth hearing has evolved in response to bat echolocation to avoid capture. Furthermore, these moth adaptations provide selective pressure for bats to improve their insect-hunting systems and this cycle culminates in a moth-bat "evolutionary arms race".

Acoustic features

Describing the diversity of bat echolocation calls requires examination of the frequency and temporal features of the calls. It is the variations in these aspects that produce echolocation calls suited for different acoustic environments and hunting behaviors.

Frequency

Bat call frequencies range from as low as 11 kHz to as high as 212 kHz. Insectivorous aerial-hawking bats have a call frequency between 20 kHz and 60 kHz because it is the frequency that gives the best range and image acuity and makes them less conspicuous to insects. However, low frequencies are adaptive for some species with different prey and environments. Euderma maculatum, a species that feeds on moths, uses a particularly low frequency of 12.7 kHz that cannot be heard by moths.

Frequency modulation and constant frequency

Echolocation calls can be composed of two different types of frequency structure: frequency modulated (FM) sweeps, and constant frequency (CF) tones. A particular call can consist of one, the other, or both structures. An FM sweep is a broadband signal – that is, it contains a downward sweep through a range of frequencies. A CF tone is a narrowband signal: the sound stays constant at one frequency throughout its duration.

Intensity

Echolocation calls have been measured at intensities anywhere between 60 and 140 decibels. Certain bat species can modify their call intensity mid-call, lowering the intensity as they approach objects that reflect sound strongly. This prevents the returning echo from deafening the bat. High-intensity calls such as those from aerial-hawking bats (133 dB) are adaptive to hunting in open skies. Their high intensity calls are necessary to even have moderate detection of surroundings because air has a high absorption of ultrasound and because insects' size only provide a small target for sound reflection. Additionally, the so-called "whispering bats" have adapted low-amplitude echolocation so that their prey, moths, which are able to hear echolocation calls, are less able to detect and avoid an oncoming bat.

Harmonic composition

Calls can be composed of one frequency or multiple frequencies comprising a harmonic series. In the latter case, the call is usually dominated by a certain harmonic ("dominant" frequencies are those present at higher intensities than other harmonics present in the call).

Call duration

A single echolocation call (a call being a single continuous trace on a sound spectrogram, and a series of calls comprising a sequence or pass) can last anywhere from 0.2 to 100 milliseconds in duration, depending on the stage of prey-catching behavior that the bat is engaged in. For example, the duration of a call usually decreases when the bat is in the final stages of prey capture – this enables the bat to call more rapidly without overlap of call and echo. Reducing duration comes at the cost of having less total sound available for reflecting off objects and being heard by the bat.

Pulse interval

The time interval between subsequent echolocation calls (or pulses) determines two aspects of a bat's perception. First, it establishes how quickly the bat's auditory scene information is updated. For example, bats increase the repetition rate of their calls (that is, decrease the pulse interval) as they home in on a target. This allows the bat to get new information regarding the target's location at a faster rate when it needs it most. Secondly, the pulse interval determines the maximum range that bats can detect objects. This is because bats can only keep track of the echoes from one call at a time; as soon as they make another call they stop listening for echoes from the previously made call. For example, a pulse interval of 100 ms (typical of a bat searching for insects) allows sound to travel in air roughly 34 meters so a bat can only detect objects as far away as 17 meters (the sound has to travel out and back). With a pulse interval of 5 ms (typical of a bat in the final moments of a capture attempt), the bat can only detect objects up to 85 cm away. Therefore, the bat constantly has to make a choice between getting new information updated quickly and detecting objects far away.

FM signal advantages

The major advantage conferred by an FM signal is extremely precise range discrimination, or localization, of the target. J.A. Simmons demonstrated this effect with a series of elegant experiments that showed how bats using FM signals could distinguish between two separate targets even when the targets were less than half a millimeter apart. This ability is due to the broadband sweep of the signal, which allows for better resolution of the time delay between the call and the returning echo, thereby improving the cross correlation of the two. Additionally, if harmonic frequencies are added to the FM signal, then this localization becomes even more precise.

One possible disadvantage of the FM signal is a decreased operational range of the call. Because the energy of the call is spread out among many frequencies, the distance at which the FM-bat can detect targets is limited. This is in part because any echo returning at a particular frequency can only be evaluated for a brief fraction of a millisecond, as the fast downward sweep of the call does not remain at any one frequency for long.

CF signal advantages

The structure of a CF signal is adaptive in that it allows the CF-bat to detect both the velocity of a target, and the fluttering of a target's wings as Doppler shifted frequencies. A Doppler shift is an alteration in sound wave frequency, and is produced in two relevant situations: when the bat and its target are moving relative to each other, and when the target's wings are oscillating back and forth. CF-bats must compensate for Doppler shifts, lowering the frequency of their call in response to echoes of elevated frequency – this ensures that the returning echo remains at the frequency to which the ears of the bat are most finely tuned. The oscillation of a target's wings also produces amplitude shifts, which gives a CF-bat additional help in distinguishing a flying target from a stationary one.

Additionally, because the signal energy of a CF call is concentrated into a narrow frequency band, the operational range of the call is much greater than that of an FM signal. This relies on the fact that echoes returning within the narrow frequency band can be summed over the entire length of the call, which maintains a constant frequency for up to 100 milliseconds.

Acoustic environments of FM and CF signals

A frequency modulated (FM) component is excellent for hunting prey while flying in close, cluttered environments. Two aspects of the FM signal account for this fact: the precise target localization conferred by the broadband signal, and the short duration of the call. The first of these is essential because in a cluttered environment, the bats must be able to resolve their prey from large amounts of background noise. The 3D localization abilities of the broadband signal enable the bat to do exactly that, providing it with what Simmons and Stein (1980) call a "clutter rejection strategy". This strategy is further improved by the use of harmonics, which, as previously stated, enhance the localization properties of the call. The short duration of the FM call is also best in close, cluttered environments because it enables the bat to emit many calls extremely rapidly without overlap. This means that the bat can get an almost continuous stream of information – essential when objects are close, because they will pass by quickly – without confusing which echo corresponds to which call.

A constant frequency (CF) component is often used by bats hunting for prey while flying in open, clutter-free environments, or by bats that wait on perches for their prey to appear. The success of the former strategy is due to two aspects of the CF call, both of which confer excellent prey-detection abilities. First, the greater working range of the call allows bats to detect targets present at great distances – a common situation in open environments. Second, the length of the call is also suited for targets at great distances: in this case, there is a decreased chance that the long call will overlap with the returning echo. The latter strategy is made possible by the fact that the long, narrowband call allows the bat to detect Doppler shifts, which would be produced by an insect moving either towards or away from a perched bat.

Neural mechanisms

Because bats use echolocation to orient themselves and to locate objects, their auditory systems are adapted for this purpose, highly specialized for sensing and interpreting the stereotyped echolocation calls characteristic of their own species. This specialization is evident from the inner ear up to the highest levels of information processing in the auditory cortex.

Inner ear and primary sensory neurons

Both CF and FM bats have specialized inner ears which allow them to hear sounds in the ultrasonic range, far outside the range of human hearing. Although in most other aspects, the bat's auditory organs are similar to those of most other mammals, certain bats (horseshoe bats, Rhinolophus spp. and the moustached bat, Pteronotus parnelii) with a constant frequency (CF) component to their call (known as high duty cycle bats) do have a few additional adaptations for detecting the predominant frequency (and harmonics) of the CF vocalization. These include a narrow frequency "tuning" of the inner ear organs, with an especially large area responding to the frequency of the bat's returning echoes.

The basilar membrane within the cochlea contains the first of these specializations for echo information processing. In bats that use CF signals, the section of the membrane that responds to the frequency of returning echoes is much larger than the region of response for any other frequency. For example, in the greater horseshoe bat, Rhinolophus ferrumequinum, there is a disproportionately lengthened and thickened section of the membrane that responds to sounds around 83 kHz, the constant frequency of the echo produced by the bat's call. This area of high sensitivity to a specific, narrow range of frequency is known as an "acoustic fovea".

Odontocetes (toothed whales and dolphins) have similar cochlear specializations to those found in bats. Odontocetes also have the highest neural investment of any cochleae reported to date with ratios of greater than 1500 ganglion cells/mm of basilar membrane.

Further along the auditory pathway, the movement of the basilar membrane results in the stimulation of primary auditory neurons. Many of these neurons are specifically "tuned" (respond most strongly) to the narrow frequency range of returning echoes of CF calls. Because of the large size of the acoustic fovea, the number of neurons responding to this region, and thus to the echo frequency, is especially high.

Inferior colliculus

In the Inferior colliculus, a structure in the bat's midbrain, information from lower in the auditory processing pathway is integrated and sent on to the auditory cortex. As George Pollak and others showed in a series of papers in 1977, the interneurons in this region have a very high level of sensitivity to time differences, since the time delay between a call and the returning echo tells the bat its distance from the target object. While most neurons respond more quickly to stronger stimuli, collicular neurons maintain their timing accuracy even as signal intensity changes.

These interneurons are specialized for time sensitivity in several ways. First, when activated, they generally respond with only one or two action potentials. This short duration of response allows their action potentials to give a very specific indication of the exact moment of the time when the stimulus arrived, and to respond accurately to stimuli that occur close in time to one another. In addition, the neurons have a very low threshold of activation – they respond quickly even to weak stimuli. Finally, for FM signals, each interneuron is tuned to a specific frequency within the sweep, as well as to that same frequency in the following echo. There is specialization for the CF component of the call at this level as well. The high proportion of neurons responding to the frequency of the acoustic fovea actually increases at this level.

Auditory cortex

The auditory cortex in bats is quite large in comparison with other mammals. Various characteristics of sound are processed by different regions of the cortex, each providing different information about the location or movement of a target object. Most of the existing studies on information processing in the auditory cortex of the bat have been done by Nobuo Suga on the mustached bat, Pteronotus parnellii. This bat's call has both CF tone and FM sweep components.

Suga and his colleagues have shown that the cortex contains a series of "maps" of auditory information, each of which is organized systematically based on characteristics of sound such as frequency and amplitude. The neurons in these areas respond only to a specific combination of frequency and timing (sound-echo delay), and are known as combination-sensitive neurons.

The systematically organized maps in the auditory cortex respond to various aspects of the echo signal, such as its delay and its velocity. These regions are composed of "combination sensitive" neurons that require at least two specific stimuli to elicit a response. The neurons vary systematically across the maps, which are organized by acoustic features of the sound and can be two dimensional. The different features of the call and its echo are used by the bat to determine important characteristics of their prey. The maps include:

Auditory cortex of a bat
A FM-FM area
B CF-CF area
C Amplitude-sensitive area
D Frequency-sensitive area
E DSCF area
  • FM-FM area: This region of the cortex contains FM-FM combination-sensitive neurons. These cells respond only to the combination of two FM sweeps: a call and its echo. The neurons in the FM-FM region are often referred to as "delay-tuned", since each responds to a specific time delay between the original call and the echo, in order to find the distance from the target object (the range). Each neuron also shows specificity for one harmonic in the original call and a different harmonic in the echo. The neurons within the FM-FM area of the cortex of Pteronotus are organized into columns, in which the delay time is constant vertically but increases across the horizontal plane. The result is that range is encoded by location on the cortex, and increases systematically across the FM-FM area.
  • CF-CF area: Another kind of combination-sensitive neuron is the CF-CF neuron. These respond best to the combination of a CF call containing two given frequencies – a call at 30 kHz (CF1) and one of its additional harmonics around 60 or 90 kHz (CF2 or CF3) – and the corresponding echoes. Thus, within the CF-CF region, the changes in echo frequency caused by the Doppler shift can be compared to the frequency of the original call to calculate the bat's velocity relative to its target object. As in the FM-FM area, information is encoded by its location within the map-like organization of the region. The CF-CF area is first split into the distinct CF1-CF2 and CF1-CF3 areas. Within each area, the CF1 frequency is organized on an axis, perpendicular to the CF2 or CF3 frequency axis. In the resulting grid, each neuron codes for a certain combination of frequencies that is indicative of a specific velocity.
  • Doppler shifted constant frequency (DSCF) area: This large section of the cortex is a map of the acoustic fovea, organized by frequency and by amplitude. Neurons in this region respond to CF signals that have been Doppler shifted (in other words, echoes only) and are within the same narrow frequency range to which the acoustic fovea responds. For Pteronotus, this is around 61 kHz. This area is organized into columns, which are arranged radially based on frequency. Within a column, each neuron responds to a specific combination of frequency and amplitude. Suga's studies have indicated that this brain region is necessary for frequency discrimination.

Whales

Diagram illustrating sound generation, propagation and reception in a toothed whale. Outgoing sounds are cyan and incoming ones are green.

Biosonar is valuable to both toothed whales (suborder Odontoceti), including dolphins, porpoises, river dolphins, killer whales and sperm whales, and baleen whales (suborder Mysticeti), including right, bowhead, pygmy right, and gray whales and rorquals, because they live in an underwater habitat that has favourable acoustic characteristics and where vision is often extremely limited in range due to absorption or turbidity. Odontocetes are generally able to hear sounds at ultrasonic frequencies while mysticetes hear sounds within the infrasonic frequency regime.

Evolution

Cetacean evolution consisted of three main radiations. Throughout the middle and late Eocene periods (49-31.5 million years ago), archaeocetes, primitive toothed Cetacea that arose from terrestrial mammals, were the only known cetaceans. These primitive aquatic mammals did not possess the ability to echolocate, although they did have slightly adapted underwater hearing. The morphology of acoustically isolated ear bones in basilosaurid archaeocetes indicates that this order had directional hearing underwater at low to mid frequencies by the late middle Eocene. However, with the extinction of archaeocetes at the onset of the Oligocene, two new lineages composed a second radiation. These early mysticetes (baleen whales) and odontocetes can be dated back to the middle Oligocene in New Zealand. Based on past phylogenies, it has been found that extant odontocetes are monophyletic; however, echolocation evolved twice, convergently, along the odontocete lineage: once in Xenorophus, an oligocene stem odontocete, and once in the crown odontecetes  Dispersal rates routes of early odontocetes included transoceanic travel to new adaptive zones. The third radiation occurred later in the Neogene, when present dolphins and their relatives evolved to be the most common species in the modern sea.

There are several theories to explain the evolution of echolocation. There are two proposed drives for the hypotheses of cetacean radiation, one biotic and the other abiotic. The first, adaptive radiation, is the result of a rapid divergence into new adaptive zones. This results in diverse, ecologically different clades that are incomparable. Clade Neocete (crown cetacean) evolved from archaeocetes and dispersed across the world's oceans, estuaries, and rivers. These ecological opportunities were the result of abundant dietary resources with low competition for hunting. This hypothesis of lineage diversification, however, can be unconvincing due to a lack of support for rapid speciation early in cetacean history. A second, more abiotic drive is better supported.

Physical restructuring of the oceans has played a role in echolocation radiation. This was a result of global climate change at the Eocene-Oligocene boundary; from a greenhouse to an icehouse world. Tectonic openings created the Southern ocean with a free flowing Antarctic Circumpolar current. These events allowed for a selection regime characterized by the ability to locate and capture prey in turbid river waters, or allow odontocetes to invade and feed at depths below the photic zone. Further studies have found that echolocation below the photic zone could have been a predation adaptation to diel migrating cephalopods. Since its advent, there has been adaptive radiation especially in the family Delphinidae (dolphins) in which echolocation has become extremely derived.

Four proteins have been found to play a major role in toothed whale echolocation. Prestin, a motor protein of the outer hair cells of the inner ear of the mammalian cochlea, is associated with hearing sensitivity. It has undergone two clear episodes of accelerated protein evolution in cetaceans. The first episode of acceleration is connected to odontocete divergence, when echolocation first developed, and the second occurs with the increase in echolocation frequency seen in the family Delphinioidae. Tmc1 and Pjvk are also two proteins related to hearing sensitivity: Tmc1 is associated with hair cell development and Pjvk is associated with hair cell function. Adaptations in the protein Tmc1 are related to the evolution of high-frequency hearing and molecular evolution of Tmc1 and Pjvk are indicative of positive selection for echolocation in odontocetes. Cldn14, a member of the tight junction proteins which form barriers between inner ear cells, shows the same evolutionary pattern as Prestin. The two events of protein evolution, for Prestin and Cldn14, occurred at the same times as the tectonic opening of the Drake Passage (34-31 Ma) and Antarctic ice growth at the Middle Miocene climate transition (14 Ma), with the divergence of odontocetes and mysticetes occurring with the former, and the speciation of Delphinioidae with the latter.

The evolution of two cranial structures has been hypothesized to be linked to echolocation. Cranial telescoping developed first in xenorophids, evolving further in stem odontocetes, until the crown odontocetes show full cranial telescoping, with an overlap between the frontal and maxilla bones and a displacement of the external nares posteriorly. Movement of the external nares may have allowed for a larger nasal apparatus and melon for echolocation. This change occurred after the divergence of the neocetes from the basilosaurids. The first shift towards cranial asymmetry occurred in the Early Oligocene, prior to the xenorophids. A xenorophid fossil (Cotylocara macei) has cranial asymmetry, and shows other indicators of echolocation. However, basal xenorophids lack cranial asymmetry, indicating that cranial asymmetry likely evolved twice. Extant odontocetes have asymmetric nasofacial regions; generally, the median plane is shifted to the left and structures on the right are larger. Both cranial telescoping and asymmetry are hypothesized to be associated with the sound production necessary for echolocation.

Mechanism

Thirteen species of extant odontocete evolved narrow-band high-frequency (NBHF) echolocation in four separate, convergent events. These species include the families Kogiidae (pygmy sperm whales) and Phocoenidae (porpoises), as well as some species of the genus Lagenorhynchus, all of Cephalorhynchus, and the La Plata dolphin. NBHF is thought to have evolved as a means of predator evasion; NBHF-producing species are small relative to other odontocetes, making them viable prey to large species such as the orca. However, because three of the groups developed NBHF prior to the emergence of the orca, predation by other, ancient, raptorial odontocetes must have been the driving force for the development of NBHF, not predation by the orca. Orcas, and, presumably, ancient, raptorial odontocetes such as Acrophyseter, are unable to hear frequencies above 100 kHz.

Another reason for variation in echolocation is habitat. For all sonar systems the limiting factor deciding whether a returning echo is detected is the echo-to-noise ratio (ENR). The ENR is given by the emitted source level (SL) plus the target strength, minus the two-way transmission loss (absorption and spreading) and the received noise. Animals will adapt either to maximize range under noise-limited conditions (increase source level) or to reduce noise clutter in a shallow and/or littered habitat (decrease source level). In cluttered habitats, such as coastal areas, prey ranges are smaller, and species such as Commerson's dolphin (Cephalorhynchus commersonii) have lowered source levels to better suit their environment.

Toothed whales emit a focused beam of high-frequency clicks in the direction that their head is pointing. Sounds are generated by passing air from the bony nares through the phonic lips. These sounds are reflected by the dense concave bone of the cranium and an air sac at its base. The focused beam is modulated by a large fatty organ known as the 'melon'. This acts like an acoustic lens because it is composed of lipids of differing densities. Most toothed whales use clicks in a series, or click train, for echolocation, while the sperm whale may produce clicks individually. Toothed whale whistles do not appear to be used in echolocation. Different rates of click production in a click train give rise to the familiar barks, squeals and growls of the bottlenose dolphin. A click train with a repetition rate over 600 per second is called a burst pulse. In bottlenose dolphins, the auditory brain response resolves individual clicks up to 600 per second, but yields a graded response for higher repetition rates.

It has been suggested that some smaller toothed whales may have their tooth arrangement suited to aid in echolocation. The placement of teeth in the jaw of a bottlenose dolphin, for example, are not symmetrical when seen from a vertical plane, and this asymmetry could possibly be an aid in the dolphin sensing if echoes from its biosonar are coming from one side or the other. However, this idea lacks experimental support.

Echoes are received using complex fatty structures around the lower jaw as the primary reception path, from where they are transmitted to the middle ear via a continuous fat body. Lateral sound may be received through fatty lobes surrounding the ears with a similar density to water. Some researchers believe that when they approach the object of interest, they protect themselves against the louder echo by quietening the emitted sound. In bats this is known to happen, but here the hearing sensitivity is also reduced close to a target.

Oilbirds and swiftlets

A Palawan swiftlet (Aerodramus palawanensis) flies in complete darkness inside the Puerto Princesa subterranean river cave.

Oilbirds and some species of swiftlet are known to use a relatively crude form of echolocation compared to that of bats and dolphins. These nocturnal birds emit calls while flying and use the calls to navigate through trees and caves where they live.

Shrews, tenrecs and rats

Terrestrial mammals other than bats known or thought to echolocate include two shrew genera (Sorex and Blarina), the tenrecs of Madagascar and solenodons. These include the wandering shrew (Sorex vagrans), the common or Eurasian shrew (Sorex araneus), and the short-tailed shrew (Blarina brevicauda). The nature of shrew sounds unlike those of bats are low amplitude, broadband, multi-harmonic and frequency modulated. They contain no 'echolocation clicks' with reverberations and would seem to be used for simple, close range spatial orientation. In contrast to bats, shrews use echolocation only to investigate their habitat rather than additionally to pinpoint food.

There is evidence that blinded laboratory rats can use echolocation to navigate mazes.

Echolocation jamming

Echolocation systems are susceptible to interference known as echolocation jamming or sonar jamming. Jamming occurs when non-target sounds interfere with target echoes. Jamming can be purposeful or inadvertent and can be caused by the echolocation system itself, other echolocating animals, prey, or humans. Echolocating animals have evolved to minimize jamming; however, echolocation avoidance behaviors are not always successful.

Background noise can also interfere with echolocation-based tasks via masking - a mechanism whereby noise interferes with the auditory perception of a signal - and via distraction - a mechanism whereby animals allocate finite attentional resources to noise rather than the signal.

Avoidance by prey animals

Galleria mellonella exhibits predator avoidance behaviors such as dropping, looping, and freezing when emitters sent out ultrasound waves, indicating that G. mellonella can both detect and differentiate between ultrasound frequencies used by predators or from other members of their species. Members of the Saturniidae moth family, which include giant silk moths, have been observed using their large wings to deflect the ultrasonic signals of microbats.

Cryogenics

From Wikipedia, the free encyclopedia https://en.wikipedia.org/wiki/Cryogenics...