Audio Loop Panel

Editor: We weren't able to make the SHHH convention in Cherry Hill, NJ, this year, but we're hoping to get to the Seattle convention in 2002. Fortunately, Cheryl Heppner of NVRC did her usual outstanding job of reporting, and she's given us permission to pass along her reports. Here's her report on the Audio Loop Panel.

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This workshop is the second part of the Assistive Listening System series. Last year's workshop was on Infrared Listening Technologies and next year's conference in Seattle will cover FM systems. Assistive listening systems are one of the best tools people with hearing loss have to help communicate in meetings and noisy situations.

The panel moderator was Ted Simons, owner of a company called Connections Unlimited. He is clear about his bias. His e-mail address is "InfraTed."

Panel members were:
Charles Beatty, Audex
Leon Pieters, Ampetronic, Ltd.
George DeVilbiss, DeVilbiss Development Co.
Andy Olson, Williams Sound

TED SIMONS

For any listening system to be useful, there are three assumptions:
1. The source material (voice, music, etc.) must be competently presented to the carrier system.
2. From the carrier system to the ear, the system is fully functional with no pops, hisses, etc.
3. The system installation conforms to professional standards and installation practices.

The telecoil on a hearing aid is most important. It must be a good one with a strong signal, or nothing else will help. The United Kingdom has standards for telecoils but there are no such standards in the U.S.

CHARLES BEATTY

Audio loops use a magnetic field as a transmitter carrier. The telecoil functions as a tiny antenna. It receives the signal, and you adjust the volume on your hearing aid to a comfortable loudness.

Audio loops are not tuned. If you put two in the same proximity, you will be able to hear the information from both. In the early days of SHHH conventions, when audio loops were used in the workshops, you could go into the hall and hear 3-4 people talking from different workshops at one time.

Current is driven into the wire of the loop and creates a magnetic field. The magnet is attracted by ferrous metal. If you have any nearby the audio loop, it will cause distortion.

Audio loop signals can also be picked up outside a room. Small loops contain the signal better than larger ones.

In the U.S., the biggest problem is that so few people have telecoils in their hearing aids. Small hearing aids in the canal of the ear predominate and it is difficult to get a telecoil in their small space.

LEON PIETERS

Some people mistakenly say audio loops are electromagnetic. It's important to remember that they are magnetic only. Cell phones are electromagnetic and many people are worried about the radiation emitted. There is no such concern with audio loops.

Ampetronic, his company, is the largest manufacturer of audio loops in Europe. Among the positives of using audio loops as opposed to other listening systems: They use a built-in telecoil, have internal tonal connection, need no extra receiver, and have none of the hygiene problems associated with earpieces. By using the built-in telecoil, you do not call attention to your need for the listening system, which appeals to some people.

Ampetronic uses audio loop systems all over -- in places of worship, theaters, autos, buses, banks, ticket booths, elevators. He has worked with Otis to build in audio loops on elevators. Gas station pumps that talk back can be outfitted with audio loops, as can drive thru restaurants like MacDonald's and Taco Bell.

They have done a large commercial concern with 72 teaching rooms, all with low-spill audio loops.

To specify loop systems, you need to know:
1. Coverage - people want complete coverage of a room or theater so they can sit where they choose.
2. Amplifier type.
3. Spillover (you can hear 2-3 loop sizes away, about 100 feet).
4. How you will interface with the sound or public address system, fire alarm and other systems. (He believes that in Europe it will be mandatory in 5 years to have audioloops for emergency situations.)

Building materials make a difference. In Britain there is a great deal more timber, mortar, concrete and stone in very old buildings, materials that are not magnetic. He's placed a 40,000 square foot outside cable 30 feet above the ground, 1,500 feet long, as his largest audio loop system. Metal in buildings can create great difficulty. You need to also check for power frequency and interference. Then there's the issue of who installs the system. Most electricians don't have the knowledge or training to do this.

The worst place for installation of an audio loop system is at head height. Floor or ceiling installation is best. Cable type is important. He has used copper tape one hundredth of an inch thick.

Some people complain of hums. Multiple grounding is worsened by induction. And one must watch out for the use of electric guitars.

There are spill systems to cut signals outside of a room.

CHARLES BEATTY

In the U.S. only about 20% of hearing aids sold have telecoils that people use. Loops must be engineered to provide real service to people, and few people in the U.S. know how to do this. Often a facility will also have infrared and FM systems for the rest of the people without telecoils.

GEORGE DEVILBISS

Most people attending this workshop are interested in what they can do for a meeting room for their chapter. A simple audio loop will work well for most people. He has generally used 18 gauge wire in a loop for a small room. This wire's thickness is 1/2 the size of a lamp cord.

DISCUSSION

Some people think that the more times you wrap a wire around, the better the audio loop, but instead that weakens it. People get a 300-watt amplifier and several turns of wire to make a loop. This is actually in violation of the Fire Code. Fire Code regulations are an important reason to use a current driving amplifier, not a voltage driving amplifier. You don't need voltage to make an audio loop work, only current. A current amplifier applies a constant amount of current to create a magnetic field.

The bigger the diameter of the wire, the less resistance and the better the magnetic field.

Many people make the mistake of trying to use a powerful amplifier when little power is needed.

George DeVilbiss is an expert at making small meeting rooms work with his pure approach to audio loops.

Audio loop installations have to be given cost estimates based on each situation.

Churches with light dimmers create huge problems for audio loops. They create a buzz "like you wouldn't believe." (George DeVilbiss)

ANDY OLSON

Williams Sound has neckloops that can be used with phones and pay phones. The law requires all wired phones to be hearing aid compatible. They have mini audio loops inside them. Pay phones have push buttons for amplifiers and telecoil access.

Q: Why does it cost so much for receivers when one bought from Radio Shack can be converted fast and cheaply?
A: Because the companies selling them have to buy all the individual parts -- plastic cases, components -- and don't sell enough receivers to get a low cost for the parts.

Q: Is there a technical solution for the noise created in a telecoil-equipped hearing aid when you get close to a computer monitors?
A: Computer monitors use CRT. You can choose flat panel monitors and laptops, which don't make telecoils buzz because they use the different LCD technology. However, even newer monitors with CRT will improve.

COMMENTS