Frye FONIX 7000, Operator'S Manual

Page: 95 / 216

Basic Sound Chamber Tests
87
2. Use [F2] to select CRV 1. (Press [F2]. Use [
∨, ∧
] to select CRV 1. Use [>] to
complete the selection and close the pop-up menu.)
3. Use [F5] to select DIG SPEECH in the same manner as described above.
4. Use [
∨, ∧
] to select a normal speech amplitude, such as 65 dB SPL.
5. Make sure the digital noise suppression feature is enabled on the hearing
aid, and set it up for testing in the sound chamber.
6. Press [START] to begin the measurement. When the response curve has sta-
bilized, press [STOP] to stop the measurement.
7. Use [F2] to select CRV 2.
8. Use [F5] to select COMPOSITE.
9. Make sure the signal amplitude is the same as selected in Step 4.
10. Press [START] to begin the measurement. Leave the signal on for at least 15
seconds. This should allow the noise suppression feature time to activate.
When the measurement has stabilized, press [STOP].
11. Compare CRV 1 and CRV 2. If the curves are right on top of each other, the
aid is responding to the Digital Speech signal just as it would respond to the
Composite signal. This could be an indication that the digital suppression
feature is either not enabled or not present on the hearing aid. Figure 3.5.4
gives an example of a hearing aid that is amplifying the Digital Speech sig-
nal and suppressing the Composite signal.
Figure 3.5.4—Digital Noise Suppression test. CRV 1 was measured with Digital Speech. CRV 2
was measured with the Composite signal.