Frye FONIX 7000, Operator'S Manual

Page: 75 / 216

Basic Sound Chamber Tests
67
Figure 3.3.7—Testing Wireless CROS Hearing Aids
4. Place the receiver on top of the lid of the test chamber. The total depth of
the lid of the test chamber is about 5 ½ inches (14 cm). To increase the total
separation, place foam on the top of the test chamber until the total separa-
tion equals that recommended by the aid manufacturer.
5. Attach the coupler to the receiver just as you would for an ordinary BTE or
eyeglass aid.
6. Align the receiver and coupler assembly on the top of the test chamber so
that the receiver is exactly parallel to the transmitter in the test chamber.
7. Test as you would any ordinary hearing aid.
Wireless BICROS
BICROS systems have two microphones: one on the transmitter side and the
other on the receiver side.
1. Test the receiver side as an ordinary hearing aid first.
2. Arrange the transmitter parallel to the receiver, but as far as possible from
it while still in the chamber. You may have to unscrew the ear hooks one-
quarter turn to accomplish this. Fun-Tak may help to keep the units in posi-
tion, but be careful not to obstruct the sound paths to the microphones.
3. Test the hearing aid again. Adding the transmitter should increase the gain
by the amount specified by the manufacturer. It is not possible to get exact
measurements by this measure because at least one of the microphones will
not be at the reference point.
d
Receiver/Coupler Assembly
located parallel to Transmitter,
at specified distance (
d )
(see manuf. specs).
Place foam under assembly
if necessary to achieve
specified distance “
d .”
Transmitter located
at Reference Point