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About FM Assistive Listening Systems

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FM Assistive Listening Systems

What is FM?

What's the benefit to you?

How does FM technology reduce background noise and make listening easier?

Why use a portable FM assistive listening system?

What are some advantages of Large Area FM Assistive Listening Systems?

How do FM Assistive Listening Systems work?

Do FM users still need to use T-coil?

Where are FM Assistive Listening Systems used?

Can non-hearing impaired people use FM Assistive Listening Systems?

Are there FM Assistive Listening Systems for personal use?

Are the two FCC FM frequency ranges 72-76 MHz and 216-217 MHz compatible?

What is FM?

FM stands for "frequency modulation" and is a common form of radio transmission. FM is one of several wireless technologies that transmit sounds directly to a hard of hearing person for optimal clarity and better understanding.

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What's the benefit to you?

FM provides improved listening clarity for people with hearing loss who experience difficulty and fatigue, when trying to understand speech, because of distance, reverberation, and distracting background noise.

  •  Reduced distracting background noise

  •  Reduced reverberation and sound distortion

  •  Reduced listening fatigue

  •  Improved voice clarity and understanding

  •  Improved hearing at a distance from the speaker

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How does FM technology reduce background noise and make listening easier?

The FM transmitter's microphone picks up a speaker's words within inches of their mouth. Consequently, the sound that the listener hears (via their personal receiver) is in its optimal state: free from attenuation (natural volume decay over distance), reverberation and distortion, and (if unidirectional, noise canceling microphones are used) background noise. The listener's headphones may also help to partially block additional background noise surrounding the listener. If the hearing aid’s “T” program (telecoil) is selected, to listen via an inductive device such as a neck loop or inductive ear hooks (instead of headphones), then the hearing aid’s external microphone is automatically disabled; eliminating annoying "feedback" and greatly reducing distracting background noise.

These beneficial strategies provide the listener with a much clearer signal from the sound source. This process is referred to as, improving the ‘speech to noise ratio’ (SpNR) or 'signal to noise ratio' (SNR). Improving the SpNR is the most beneficial strategy available for improving speech comprehension for hard of hearing people.

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Why use a portable FM assistive listening system?

The greatest advantage of a portable FM assistive listening system is that it is easy to set up and puts the user in complete control.

For instance, the COMTEK AT-216 FM Assistive Listening System comes in a very practical carry case. The system is portable and completely self-contained. The owner of the system has total control, and is not dependent on anyone for maintenance or hygiene issues. The system is battery powered and can be taken anywhere. The user simply gives the wireless transmitter to any presenter, teacher, work associate or friend who they wish to hear. The system is also extremely versatile and can be used to listen to other sound sources such as TV or audio from a facility's soundboard. You can even simultaneously monitor and record presentations for later review.

Having autonomy over a system that allows better hearing and understanding, and being able to use it where and when you need it is extremely important to hard of hearing individuals. Attempting to hear in many challenging sound environments, without such technology, can lead to frustration, fatigue and withdrawal from participation.

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What are some advantages of Large Area FM Assistive Listening Systems?

 FM is easy to set up and can be used in many environments.

  •  From a business perspective, businesses can install Large Area FM assistive listening systems very easily without disturbing furnishings or the building structure. The most that might be required would be the mounting of an external aerial but often the transmitter's built-in aerial will provide sufficient range. FM systems provide compliance with ADA accessibility requirements. If more than one systems is needed in adjacent rooms, an additional system can be installed using a separate FM frequency without interference.

  •  From a user perspective, using wireless microphones that transmit to a personal receiver is the most effective method for improving the Speech to Noise Ratio for the hard of hearing listener and increasing their ability to comprehend what is said.

  •  FM Assistive Listening Systems use a dedicated frequency range. The FCC, in the United States, has assigned two separate FM frequency ranges for assistive listening systems. This is important in order to minimize issues related to interference from other radio users. The established 72-76 MHz range is somewhat prone to intermittent interference from emergency vehicles etc. The newer 216-217 MHz range is assigned exclusively for low power assistive listening systems and offers greater immunity from interference.

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How do FM Assistive Listening Systems work?

  1. Audio input from a microphone, TV, audio player or any electronic sound source feeds into an FM transmitter.
    The use of high quality, unidirectional, noise canceling microphones can greatly improve the clarity of the sound source: microphone placement is also important.
    The transmitter may be permanently installed as in a church or theatre, or the transmitter may be portable. Portable transmitters may be a hand held microphone or  a small body pack unit, worn on a belt clip, by a teacher or presenter.

  2. The FM radio frequency signal is picked up by the user's FM receiver.
    The FM receiver may be a small body pack unit worn on a belt-clip such as the COMTEK PR-216, or it may even be a miniature component built-in to or attached to a hearing aid. Each user requires a compatible FM receiver that is usually maintained and supplied by the venue.

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Do FM users still need T-Coil?

Yes and no - but probably yes...
Getting the received sound to your hearing aid isn't quite as simple as we might hope. Those last few inches from a belt-clip worn receiver to your ear-level hearing aid present several challenges.

  •  The most logical solution is to have the receiver be a component of your hearing aid. Phonak has been a leader in FM receiver and  hearing aid integration. Until recently, hearing aid FM receivers had to be attached to a special boot/shoe on the base of the BTE hearing aid. The boot/shoe provided an adapter or interface to the direct audio input (DAI) terminals on the base of the BTE hearing aid. Unfortunately, this configuration, of three components instead of one, contributed to fragility of connections and increased size of the BTE hearing aid. As hearing aid components have become smaller, Phonak has been working to integrate the FM receiver into the hearing aid and eliminate the need for a boot/shoe. Practical issues associated with this solution, related to miniaturization and integration, include: increased cost, increased power requirements, sound quality, FM frequency selection etc. Although this technology is often used in specialized environments, such as school classrooms for hearing impaired children, it has not been a widely available or viable solution for the majority of hearing aid users.
    Phonak BTE hearing aid FM receivers

  •  The most obvious solution is to use headphones. However, headphones have their own set of issues. Some hearing aid users may experience hearing aid feedback when wearing headphones. In public facilities, there maybe concerns related to hygiene issues of shared headphones and the replacement of headphone cushions. Systems that use ear buds or stethoscope style headphones require the removal of the user's custom programmed hearing aids; a solution which is both counter productive and unacceptable. Also, believe it or not, hard of hearing people may be reluctant to wear headphones that advertise their disability to all. How successful is a system that people feel uncomfortable about and are reluctant to use?

  •  The best solution might be to use direct audio input wires. Best, because this offers a direct connection from the receiver to the hearing aid that is not subject to electromagnetic interference or background noise. However, this would involve using delicate connector wires and would only be helpful to a small percentage of BTE hearing aid users whose hearing aids are fitted with DAI capability.

  •  And that brings us back to T-coil. If a neck loop or inductive ear hooks are plugged into the FM receiver, the user can switch their hearing aid to the "T" program, cut out background noise and listen to the audio transmission without having to wear headphones or be annoyed by feedback.

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Where are FM Assistive Listening Systems used?

Anywhere!

  •  Large public facilities like churches, concert halls and meeting rooms are ideal places for Large Area Assistive Listening Systems.

  •  Hard of hearing people can easily take the portable AT-216 assistive listening system with them to presentations, lectures, meetings and social gatherings. Because it is completely battery powered, it can be used anywhere, indoors or outside.

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Can non-Hearing Impaired people benefit from FM Assistive Listening Systems?

Yes, and they do! Think of tour guides, interactive exhibitions, factory tours, language translation etc. All a non-hearing impaired person needs, is a receiver and a set of headphones or ear buds. Non-hearing impaired users are often impressed by how much easier it is to hear clearly in many sound environments with a greatly improved speech to noise ratio. Non-hearing impaired users will share the benefits of reduced background noise, reverberation, sound distortion and listening fatigue plus improved clarity and ease of listening at a distance.

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Are there FM Assistive Listening Systems for personal use?

Yes, personal assistive listening devices (ALDs), utilizing FM technology, available from TecEar include:

The COMTEK AT-216 FM Assistive Listening System comes in a very practical carry case. The system is completely self-contained. The owner of the system has total control, and is not dependent on anyone for maintenance or hygiene issues. The system is completely battery powered and can be taken anywhere. The user simply gives the wireless transmitter to any presenter, teacher, work associate or friend who they wish to hear. The system is also extremely versatile and can be used to listen to other sound sources such as TV or audio from a facility's soundboard. You can even simultaneously monitor and record presentations for later review.

Having autonomy over a system that allows better hearing and understanding, and being able to use it where and when you need it is extremely important to hard of hearing individuals. Attempting to hear in many challenging sound environments, without such technology, can lead to frustration, fatigue and withdrawal from participation.

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Are the two FCC FM frequency ranges 72-76 MHz and 216-217 MHz compatible?

The unfortunate answer is no.
Some FM assistive listening system manufacturers are slowly phasing out the older 72-76 MHz range in favor of the newer 216-217MHz frequency range. The newer 216-217 MHz dedicated frequency range should be less prone to interference issues than the older range which is shared by other users such as emergency vehicles.
However, many facilities still use the 72-76 MHz frequency range and manufacturers supply equipment to support these installations.
Hearing aid manufacturers that integrate receivers into BTE hearing aids, such as Phonak, utilize the newer 216-217 MHz frequency range. COMTEK's use of the newer 216-217 MHz range offers full compatibility with hearing aid manufacturers' FM receivers.
COMTEK Assistive Listening Frequency Chart

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Last modified: 03/25/14