Dorset Sound & Communications

Sound system design for the 21st Century

Sound Tips
Hearing Assistance Systems

 The ADA (Americans with Disabilities Act) regulations have greatly increased the use of hearing assistance in public auditoriums. Though exempt from the ADA, many churches invest in a wireless hearing assistance system for the older and hearing impaired members of their congregations. With the advancing age of our population, hearing loss due age and our noisy environment, as many 15% under 45 and 50% over 60 need hearing assistance to understand a pastors' or presenters' words. That is a significant number of your audience that may not benefit from your message. See the Sound Tip on intelligibility.

There are three predominant systems available. One uses modulated infrared (IR) light to transmit your audio. The second RF type uses a small radio transmitter. Both types transmit to the members carrying shirt pocket sized receivers or receiver headsets. A small earphone is attached with a wire to a receiver. There are many earphone options ranging from button, 'walkman' and earmold types to personal induction loops that can be used with a hearing aid T-switch. These systems insure that everyone can participate in the program, even if they have a hearing impairment. They are not confined to the old "deaf row" with wired headphones. Users can sit with their families anywhere in the room. The number of users is only constrained by the quantity of receivers available. A wireless system can accommodate as many receivers as are required. The third type is an induction loop. It is an old concept that is regaining popularity because of ADA compliance and updated equipment.

Infrared systems are the highest quality and are popular in theaters because the signal is confined to the auditorium. There is no problem with interference between systems in several rooms. Infrared emitter panels are mounted on the wall and patron can sit anywhere the emitter face is visible. Typical coverage is 4,000-10,000 square feet per panel depending on model, manufacturer, and architecture. Infrared systems are affected by sun or natural light, so are not usable outside and may be problematic in rooms with large south facing windows, skylights or clarestory vaults. Recently, energy efficient electronic fluorescent lighting systems have caused interference problems that are solved by using newer higher frequency modulated infrared transmitters. All new systems use high frequency modulation. Stereo and multichannel infrared systems are available.  IR systems are preferred on Broadway and many other performance venues as they do not transmit outside house, preventing clandestine bootleg recording. It also makes hearing assistance easy for adjacent theaters as one system cannot interfere with another. A multi-room facility can stock one type of receiver that can be used in every room. A large synagogue client in DC serves over 6000 attendees at High Holidays in 5 different chapels simultaneously on site. One model receiver (over 50 units) is used for all services without retuning.

FM radio (RF) systems cost less and transmit farther. Several hundred feet radius coverage is not unusual. RF systems transmit on one of two FM bands protected by the FCC for disability assistance. A member can sit in the lobby or parlor and still hear the service. Portable RF table top receivers can be used to send sound to a nursery or office without wires. There is little or no installation labor because the transmitter is out of sight with the sound system electronics. Local interference is a consideration, but usually not a problem. Multiple rooms can be accommodated, but each must have a distinct frequency and receivers have to be tuned for each. In recent years Listen Technologies has provided scanning, button tuned, display receivers that make the task much easier.

Induction loop systems are by far the oldest method of wireless hearing assistance. Loop systems work by looping the area to be served with cable that is attached to the output terminals of a loop amplifier. A user only has to flip the "T" switch on his hearing aid to receive the electromagnetic signal. In most European countries loops are mandated for public spaces. Potentially, a loop owner does not have to provide or maintain receivers - a great long term savings. Old loop systems required multiple turns of wire to prevent damaging the amplifier. As a result they often sounded  harsh and signal strength could be vary greatly within the loop. Newer systems use a single loop of wire and connect to modern current drive, loop specific amplifiers. Sound quality and uniformity is much improved. Care has to be taken to design and install a loop system. Loops are susceptible to local electrical fields such as heavy elelctrical feeders and power transformers. Loops can affect some dynamic microphones and magnetic musical instrument pick-ups. National hearing advocacy groups prefer the loop as a receiver is unnecessary and owner maintenance is low. In the US most behind-the-ear hearing aids are T-coil equipped. Fewer of the popular miniature in-ear hearing aids have them. It is a dilemma. Shirt pocket loop receivers are available for users without hearing aids or T-coils.

Hearing assistance systems are also used for guided tours in noisy environments, language translation and narration for the sight impaired. Call us if you need a system designed for any of these applications.

Wireless hearing assistance systems can be added to any existing sound system at any time. There are few or no controls to adjust. Give DS&C a call for help specifying and installing your church wireless hearing assistance system and then train you to use it effectively. We can also set up preventive measures and scheduled maintenance visits for the rest of your sound systems. Don't be caught unprepared. Enjoy effortless sound. Do it now! 


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