A4.33.7 Types of Listening Systems.
An assistive listening system appropriate for an assembly area for a group of persons or where the specific individuals are not known in advance, such as a playhouse, lecture hall or movie theater, may be different from the system appropriate for a particular individual provided as an auxiliary aid or as part of a reasonable accommodation. The appropriate device for an individual is the type that individual can use, whereas the appropriate system for an assembly area will necessarily be geared toward the “average” or aggregate needs of various indi-viduals [sic]. A listening system that can be used from any seat in a seating area is the most flexible way to meet this specification. Earphone jacks with variable volume controls can benefit only people who have slight hearing loss and do not help people who use hearing aids. At the present time, magnetic induction loops are the most feasible type of listening system for people who use hearing aids equipped with “T-coils,” but people without hearing aids or those with hearing aids not equipped with inductive pick-ups cannot use them without special receivers. Radio frequency systems can be extremely effective and inexpensive. People without hearing aids can use them, but people with hearing aids need a special receiver to use them as they are presently designed. If hearing aids had a jack to allow a by-pass of microphones, then radio frequency systems would be suitable for people with and without hearing aids. Some listening systems may be subject to interference from other equipment and feedback from hearing aids of people who are using the systems. Such interference can be controll-ed [sic] by careful engineering design that anticipates feedback sources in the surrounding area.
Table A2, reprinted from a National Institute of Disability and Rehabilitation Research “Rehab Brief,” shows some of the advantages and disadvantages of different types of assistive listening systems. In addition, the Architectural and Transportation Barriers Compliance Board (Access Board) has published a pamphlet on Assistive Listening Systems which lists demonstration centers across the country where technical assistance can be obtained in selecting and installing appropriate systems. The state of New York has also adopted a detailed technical specification which may be useful.
Table A2. Summary of Assistive Listening Devices
| System | Advantages | Disadvantages | Typical Applications |
|
Induction Loop Transmitter: Transducer wired to induction loop around listening area. Receiver: Self-contained induction receiver or personal hearing aid with telecoil. |
Cost-Effective Low Maintenance Easy to use Unobtrusive May be possible to integrate into existing public address system. Some hearing aids can function as receivers. |
Signal spills over to adjacent rooms. Susceptible to electrical interference. Limited portability Inconsistent signal strength Head position affects signal strength. Lack of standards for induction coil performance. |
Meeting areas Theaters Churches and Temples Conference rooms Classrooms TV viewing |
|
FM Transmitter: Flashlight-sized worn by speaker. Receiver: With personal hearing aid via DAI or induction neck-loop and telecoil; or self-contained with earphone(s). |
Highly portable Different channels allow use by different groups within the same room. High user mobility Variable for large range of hearing losses. | High cost of receivers Equipment fragile Equipment obtrusive High maintenance Expensive to maintain Custom fitting to individual user may be required. | Classrooms Tour groups Meeting areas Outdoor events One-on-one |
| Infrared Transmitter: Emitter in line-of- sight with receiver. Receiver: Self-contained. Or with personal hearing aid via DAI or induction neckloop and telecoil. | Easy to use Insures privacy or confidentiality Moderate cost Can often be integrated into existing public address system. | Line-of-sight required between emitter and receiver. Ineffective outdoors Limited portability Requires installation | Theaters Churches and Temples Auditoriums Meetings requiring confidentiality TV viewing |
Source: Rehab Brief, National Institute on Disability and Rehabilitation Research, Washington, DC, Vol. XII, No. 10, (1990).
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