Relatively Low Cost Square Dance Hearing Assistance System

System Description

The Square Dance Hearing Assistance System was designed to help those who have a hard time hearing the music and the caller at a square dance. The system is inexpensive and modular and uses easily available technology. The system is composed of three components: 1) An FM transmitter that is plugged into the caller's PA system (cost $70 caller/club); 2) A small portable FM radio receiver (cost $30 dancer); and 3) ear buds or a telecoil neckloop which plugs into the FM radio (cost <$10 dancer). This system is less expensive than other systems created just for the hearing impaired which cost approx. $600 for a transmitter and $100 for a receiver. The higher priced systems work on frequencies set aside for the hearing impaired and have less interferance and they have other features that might be needed by a hearing impaired person in special situations (such as automatically finding the frequency in use as you enter a school class room where the frequencies change from class to class). However, our experience to date indicates that for the average club square dance application the system described here is adaquate. A system diagram is shown in Figure 1.

figure showing hearing assist system

Figure 1 - Square Dance Hearing Assist System

Component 1 - C. Crane's Digital FM Transmitter

It was selected because it:

1) accepts monitor output, line out, speaker out, voice out or music out using input volume control;
2) transmits on any open FM frequency from 88-108 MHz;
3) the frequency is specified digitally and has a phase lock loop circuit to assure a specific frequency;
4) is FCC licensed;
5) transmits from 40 to 70 feet but in an open room goes 100 feet;
6) has an AC power supply;

Note: it will transmit in stereo. Cost: $70.00 from C. Crane http://www.ccrane.com/radios/fm-transmitters/fm-transmitter.aspx, It comes with a 3.5mm stereo plug and an RCA to 3.5mm stereo adapter. If you have a mono output you will need an audio adaptor Radio Shack 274-368 which has a male mono plug and accepts a stereo input, cost $3.20. If you are using a 1/4 inch output you will also need a 1/4inch to 3.5mm adaptor.

Component 2 - Portable FM Radio

Sony Walkman SRF-M37V AM/FM/Weather/TV Radio. Was selected for this application because:

1) has digital tuning to any FM band;
2) has lock button so tuning will not change during dancing and unit will not be accidentally turned on when not in use and drain batteries;
3) does not have a speaker so it is light weight;
4) has presets;
5) volume control with lots of volume;
6) ear phone jack;
7) low battery indicator;
8) relatively long battery life (40 hrs, about 10 dances);
9) belt clip;
10) can be used as a regular radio on FM, AM, TV (0-13) and weather bands.

Cost: $29 at Target
http://www.target.com/gp/detail.html/sr=1-3/
qid=1148246598/
ref=sr_1_3/601-7876051-1957708?%5Fencoding=UTF8&asin=B00008W7LS
.

Component 3 - Ear Buds or Telecoil Neckloop or Ear Links

Radio Shack (33-1106) over-the-ear ear buds. They are good for this application because:

1) 3.5mm plug to match radio;
2) will stay on ear during movement;
3) light weight.

Cost: $10.00 at Radio Shack http://www.radioshack.com/product/index.jsp?productId=2104028&cp.

Telecoil Neckloop - The Williams Sound neckloop has a 3.5mm plug and works with hearing aids equipped with a telecoil T-switch. (http://www.hearinglosshelp.com/products/pocketalker.htm#neckloop). It costs approx. $39.00 Ear links (approx. $49.00) are basically neckloops for each ear (can receive stereo) and are explained at http://www.hearinglosshelp.com/products/earlinks.htm#music_links. WARNING: Do not use a neckloop if you have a pacemaker or any medical device sensitive to magnetic fields.

This system has been used for about 1 1/2 months at several club and class square dances and with several square dance style (Hilton and other) PA systems and has been enthusiastically received by callers and dancers.

Requirements for Components

Component 1 - FM Transmitter

1) Digital frequency control;
2) AC power supply;
3) Large FM frequency range;
4) Input volume control;
5) Good range up to 100 ft in one room;
6) Relatively low cost (< $100);
7) Large acoustic signal range for musical application.

Component 2 - Portable FM Radio

1) Digital frequency control in FM range;
2) Light weight;
3) Lock on control buttons;
4) Good volume;
5) Earphone plug (ability to turn off any speaker);
6) Long battery life (40 hrs);
7) Battery low indicator (no surprises);
8) Relatively low cost (<$30.)

Component 3 - Ear Buds

1) Light weight;
2) Good frequency response;
3) Ability to stay in ear during movement;
4) 3.5mm plug or plug to match radio;
5) Relatively low cost (<$15.)

Component 3 - Telecoil Neckloop - Ear Links

Note neckloops are used by persons with hearing aids that are telecoil equipped. This allows the person to use their own hearing aid for better hearing and there is no connection required between the radio and the hearing aid. The neckloop can be worn as a neck ornament or put under shirt or blouse. The neckloop plugs into the FM radio ear phone slot. The hearing aid must be changed from the Microphone (M) setting to the telecoil (T) setting or the (MT) microphone and telecoil setting. Neckloops provide only mono (not stereo) sound.

Requirements for the neckloop are:

1) Low cost (< $10);
2) Light weight;
3) Have 3.5mm plug or plug to match radio

So far a commercial neckloop meeting the low cost has not been found but we have experimented with home made neckloops that can be constructed for <$5.00. If our experiments show these work adaquately we will describe how to make them here later.

WARNING: A NECKLOOP SHOULD NOT BE WORN BY PEOPLE WITH PACEMAKERS OR OTHER MEDICAL DEVICES SENSITIVE TO MAGNETIC FIELDS, AND, AS WITH ALL LOOPS WORN AROUND THE NECK, BE CAREFUL OF GETTING INTO A SITUATION WHERE IT COULD CHOKE YOU!

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(06/14/06)

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