Guidelines for Buildings and Facilities (ADAAG)
4.33 Assembly Areas
Figure 7: Coupling a
hearing aid to an ALS by placing the headphone over the hearing aid while
it is switched to the “T” setting.
Figure 8: Coupling a cochlear implant to an ALS using a patch cord.
DOJ Title II rule
landmark Americans with Disabilities Act (ADA), enacted on July 26, 1990,
provides comprehensive civil rights protections to individuals with
disabilities in the areas of employment (title I), State and local
government services (title II), public accommodations and commercial
facilities (title III), and telecommunications (title IV). Both the
Department of Justice and the Department of Transportation, in adopting
standards for new construction and alterations of places of public
accommodation and commercial facilities covered by title III and public
transportation facilities covered by title II of the ADA, have issued
implementing rules that incorporate the Americans with Disabilities Act
Accessibility Guidelines (ADAAG), developed by the Access Board.
U N I T E D S T A T E S A C C E S S B O A R D
ASSISTIVE LISTENING SYSTEMS
BULLETIN 9A: FOR CONSUMERS
Why is it hard to hear in some spaces?
Background noise is unwanted sound that competes with and masks the sounds you want to hear. The noise may be coming from air conditioning or heating ducts, from various kinds of equipment, or from other occupants and their activities. Who has not complained about the difficulty of hearing and understanding in a noisy restaurant or party? We live in a noisy world that seems to get noisier as the years go by!
In reverberation, the sound signals are reflected off the various surfaces of a room, bouncing around so that different parts of it get to your ears at different times. What this overlapping of sound does is blur the clarity of what you are trying to hear. The amount of reverberation is a product of room proportions and the nature of the surfacing material. Hard surfaces reflect more sound, soft ones absorb it. Excessive reverberation causes the difficulty we have in understanding public address announcements in places like transit stations, airports, and arenas. While the sound signals may be loud enough, the acoustical conditions in these spaces make comprehension difficult or impossible.
Simply turning up the volume of a hearing aid is not the answer. This just increases the loudness of both the desired sounds and the background noise and reverberation. So a different approach is needed for people who have hearing loss. An assistive listening system can bridge the gap between a sound signal and a listener’s ears, delivering the sounds you want to hear unaffected by room acoustics.
How can an assistive listening system help?
Many people who don’t wear hearing aids use an ALS in assembly areas like movie theaters, live stage productions, and auditoriums and sports arenas to make the listening task easier and more effective. ALSs are also used to supplement hearing aids.
The Americans with Disabilities Act (ADA) requires that certain kinds of public and private facilities that normally provide amplification systems for their audiences – such as theaters, movie houses, arenas and stadiums, auditoriums, meeting and lecture rooms, concert and performance halls, and courtrooms – must have assistive listening systems installed for people who want to use them. Clearly visible signs must be posted that indicate the availability of the ALS and the location in the facility where the appropriate receivers can be obtained.
How does an ALS work?
Induction loop (IL) systems use a wire around the room to transmit an electromagnetic signal that is picked up by a small device – called a telecoil -- in the hearing aid. Users simply switch on this telecoil (the “T” setting) and adjust the volume of the hearing aid, if necessary. However, not all hearing aids – particularly the very small ones – have telecoils, which are mainly used for improved telephone access. For those people whose hearing aids do contain telecoils, an IL system is the most convenient one of all – the special “receiver” being their own hearing aids (see Figure 2).
If your hearing aid doesn’t have a telecoil, or if you don’t wear a hearing aid, you can still use an IL system by wearing a receiver that has a telecoil in it. An earpiece or headset delivers the sound to your ears or through your hearing aid.
FM systems are variations on the commercial FM radio. Radio signals are broadcast by an FM transmitter connected to the sound system used in the facility. These signals are received by individual “radios” – small pocket-size receivers tuned to the specific frequency used in the transmission (see Figure 3). There are a number of alternative ways to make the receiver-to-ear connections; these will be fully discussed below.
Infrared (IR) systems operate on infrared light that is beamed from one or several IR transmitters to small, specialized receivers. There are several types of IR receivers: stethoscope-style that dangle from the ears, a headset type that fits over the ears, and a small pocket-size type similar to the FM receiver. With the first two, the receiver-to-ear connections are straightforward; they are placed directly in or on the ear (see Figure 4). The alternative ways to make the receiver-to-ear connections with the third, pocket-style IR, is the same as with FM receivers and will be discussed below.
Each system has its advantages and disadvantages. A system that works well in a courtroom would not be appropriate for a multiplex theater; an outdoor facility needs a different system than an orchestra hall. Differences in confidentially, interference, cost, installation requirements, and operability make it impossible to simply use one type of ALS in every place. Before choosing an ALS, an installer will consult with the location managers and do a site analysis to determine the most appropriate ALS type.
What kind of receivers and connections will work for me with IR and FM
For hearing aid users, the choices are more varied and depend upon whether the hearing aid incorporates a telecoil or not. If your hearing aid has a telecoil, you can set it on the T-setting and then plug a neckloop or silhouette inductor directly into a pocket-type receiver (see Figure 6). A neckloop fits around the neck like a loose necklace. A silhouette inductor is embedded in a thin plastic shape similar to a behind-the-ear hearing aid (shown in Figure 6). Silhouettes can be very useful for people with severe hearing loss.
Neckloops and silhouette inductors work the same for both FM and IR systems. As with a room IL system, the neckloop or silhouette inductor transmits an electromagnetic signal to the telecoils within the hearing aids (the “T” switch must be in the “on” position). A major advantage of using this mode of transmitting audio signals is that it utilizes the individualized adjustments made in the person’s own hearing aids.
If your hearing aid does not contain a telecoil, then you may remove the hearing aid to use headphones or earbuds, as a non-hearing aid user would do This does not work well if hearing loss is severe. Headphones can sometimes be worn over the hearing aid; it will be necessary to adjust the hearing aid volume downward and the ALS volume up to avoid interference. People who wear behind-the-ear hearing aids will have more difficulty placing headphones over their ears than those who use in-the-ear hearing aids. Aids fitted with telecoils provide a better connection.
Some hearing aid users may prefer to do both: headphones over their ears while turning the aids to the T-coil position (see Figure 7). This will work with headphones that also emit an electro-magnetic signal in addition to sound, similar to the way that hearing-aid compatible telephones operate.
Cochlear implant users are advised to bring their own patch cord to connect the implant to the ALS receiver provided by the facility (see Figure 8). This would also be necessary for people who prefer to use a direct audio input (DAI) into a “boot” under their behind-the-ear hearing aids.
What is involved in obtaining and returning ALS receivers?
Every place I go has a different system, with some working well, while
others are awful. Is there anything I can do?
If you find that a system does not work for you, advise the management. Insist that a staff member troubleshoot the system to determine the cause of the problem. This could be because of any of the reasons listed above. While the ADA requires that the operators of movie houses, theaters, auditoriums, and similar large assembly places provide such systems, national standards regulating their use are just being developed. You can suggest that facilities that need guidance on system selection, use, and maintenance consult the Board's ALS/ALD Technical Assistance Bulletin for Providers (Bulletin No. 9B). A Bulletin for Installers is also available.
The Rehabilitation Engineering Research Center on Hearing Enhancement, website www.hearingresearch.org, has a great deal of useful information on assistive listening systems. Other resources include the technical assistance center at Gallaudet University, www.gallaudet.edu, and the Access Board, www.access-board.gov. The Access Board also provides a toll-free technical assistance number at (800) 872-2253 (voice) or (800) 993-2822 (TTY). If you wish to file a complaint about the lack of functioning ALS/ALD, contact the US Department of Justice at (800) 514-0301 (voice) or (800) 514-0384 (TTY).
This technical assistance is intended solely as informal guidance; it is not a determination of the legal rights or responsibilities of entities subject to the ADA.
N I T E D S T A T E S A C C E S S B O A R D