Frye FONIX 7000 - Manual (Page 86)

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FONIX 7000 Hearing Aid Analyzer
3.4.10 Telecoil
Telecoil measurements can be performed in the Coupler screen using any of the
source signals available on the 7000 Hearing Aid Test System. During a telecoil
measurement, a magnetic field is used that is supposed to simulate the field of
a telephone receiver. A telecoil board capable of producing this field is built
into every 7000 sound chamber. When the analyzer has the ANSI option, the
external Telewand can also be used for the measurement.
Analyzer Setup
It is very important to pick a testing location that is free of magnetic disturbanc-
es, especially those caused by fluorescent lights and power lines. To do this:
1. Locate a wide range linear hearing aid with good low frequency response
and a telecoil switch.
2. Set the hearing aid to operate in the telecoil position and turn the gain con-
trol up to its full-on position.
3. Connect the hearing aid to a coupler. Don’t insert the measurement micro-
phone.
4. Walk around your possible testing location and listen for raspy humming
sounds from the hearing aid. This will be the aid responding to magnetic
fields in the room.
5. Pick a location that is as free of such sounds as possible. Rotate the aid in
all directions when looking for a good site.
Testing with the Sound Chamber Telecoil board
Every 7000 sound chamber has a built-in telecoil board that can be used for
telecoil testing.
1. Set up the hearing aid for testing in the usual way by connecting it to the
appropriate coupler and inserting the measurement microphone.
2. Enter the Coupler screen by pressing [F1] in the Opening screen.
3. Press [MENU] in the Coupler screen to open the local menu. Set the
TRANSDUCER to TELECOIL under Source Settings and press [EXIT] to
close the local menu.
4. Use [F5] to set the Source Type to Composite.
5. Press [START] to start a composite measurement.
6. Look at the RMS OUT in the Curve Characteristics box. This shows the cur-
rent output of the hearing aid to the magnetic field input.
7. Position the hearing aid for maximum output. For BTE hearing aids, this
usually occurs when the body of the aid is in a vertical position. If neces-
sary, use Fun Tak to help hold the aid in that position. See Figure 3.4.10A.