Group assistive listening devices
If there are several people with hearing loss in a group, a system that “broadcasts” what is being said is preferable to a single user device. There are several kinds of systems that do this. The primary advantage is that multiple people can benefit from these systems; the main disadvantage is that they are expensive and are not as portable as the single user devices. The main varieties include infrared, loop, and FM.
Here’s a brief comparison of the various types of group ALDs. For another perspective and more a more detailed comparison, seeCurtis Dickerson’s comparison.
For additional information, to get information on a specific device, or to purchase an assistive listening device, see:
|shopping for assistive listening devices|
|general stores for people with hearing loss|
Group ALDs Comparison
All of these systems include a single or multiple microphones that connect to some sort of central unit. The central unit controls the system and transmits the sound signal much like a radio station. Each user has a receiver that picks up the signal and sends it either to a pair of headphones, or to a hearing aid or CI. If a person with a telecoil-equipped hearing aid is using a loop system, no external receiver is required.
Infrared systems depend on a clear line of sight between the transmitter and the receiver. If someone walks between them, or if a clear line of sight is not available, the infrared systems don’t work.
FM and loop systems don’t require a line of sight, because the signals they use are able to “bend around” intervening objects. In this sense, they are more versatile.
FM and infrared systems are somewhat portable (often in the same way that a cello is portable), while the loop system are generally permanently installed in a particular room.
Because of these features and limitations, the FM systems tend to be the most versatile.
Assistive Listening System Comparison
Editor: Many of you already know Curtis Dickerson as someone who really knows his assistive listening devices. I recently saw his great overview of assistive listening systems. (These are the systems that allow a whole group of people to hear what’s being said; they are generally installed in churches, meeting halls, etc.) He graciously allowed me to share this information.
BTW, you can contact him at firstname.lastname@example.org, or check out his website at www.hearing-loss-help-co.com. Now, heeeeeerrrrrreeeeeee’s Curtis!!
ALL QUALITY SYSTEMS WILL:
1) Provide for all those that can benefit from amplification
2) Work with or without hearing aids
3) Allow users to sit anywhere.
4) Provide personal amplification control.
5) Let the HOH user select ear gear.
6) Comply with the Americans with Disabilities Act (Houses of religion are exempt).
7) Have little or no maintenance schedule.
THE THREE MAIN TYPES OF TECHNOLOGY
A) Audio Induction Loop
B) FM System
C) Infrared System
ABOUT AUDIO LOOP
How It Works: Unobtrusive wire circles perimeter of listening area. Can be installed under floor or in ceiling during construction.
Advantages: Only telecoil in hearing aid needed by user. Nothing to maintain. Sit anywhere within the loop. Possible to integrate into existing PA system.
Disadvantages: Laying wire is labor intensive. Possible interference and dead spots. There is spillover of signal. Lack of standards for telecoil performance.
Typical Use: Classroom, Meeting Area, Theater, Church and Temple, Conference Room, Public transportation vehicles.
COST: $375 to $2,400 and more
ABOUT FM SYSTEM
How It Works: An FM Radio signal is sent through the air from the microphone (speaker) and picked up by the FM Receiver (listener)
Advantages: Can sit anywhere. No need to see speaker. Portable, Simultaneous multi-lingual capability. May be integrated into existing PA system.
Disadvantages: Possible to receive interference from within and without. A channel selection switch remedies the interference.
Typical Use: Tour groups. Outdoor events, Classroom, Meeting Area, House of Religion
COST: $975 to $3,000 and more
ABOUT INFRARED SYSTEM
How It Works: Invisible light (infrared) floods the listening area. The signal that you want to hear is within this light. Users use a receiver to pick up the signal. The receiver amplifies it and sends it to the hearing aid/ears via headset/telecoil.
Advantages: No over-spill. Can be used in adjoining rooms without interference. Provides security from those outside the room. Can often be integrated into existing PA systems.
Disadvantages: Can’t be used in bright and direct sunlight. New type “efficiency” ballast from fluorescent lights may cause interference. (switching channels will solve that problem)
Typical Use: Confidentiality (court room), Live theater (no interference with the in-house radio transmitting), Church and Temple, Auditorium, TV.
COST: $1,180 TO $3,000 AND MORE