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.
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 hearmeco@telegram.infi.net, 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
