5 digital hearing aids – Frye FONIX 7000 User Manual

Page 165

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Real-Ear Measurements

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7. Press [∨] repeatedly until the chosen source is OFF.
8. Press [START] to start the measurement.
9. Instruct your client to sustain the vowel sound “eee.”
10. Press [STOP] while the “eee” is still sounding, and the curve has stabilized.

The client can now stop vocalizing.

11. Look at the amplification in the low frequencies. If it seems high, you may

consider adjusting the vent to a more open condition, to prevent occlusion-
effect discomfort.

12. Press [F2] to select the REAR 2 curve. Make sure that COMPOSITE is the

selected source type, and that the source is turned OFF. Use [F5] and [∨] to
make these selections, if necessary.

13. Press [START] to start a second measurement
14. Ask the client to sustain an “eee” sound again. Press [STOP] during the

vocalization when the measurement has stabilized. (You can then tell your
client to stop.)

15. Examine the REAR 2 curve in the lower graph and the corresponding REIR

curve in the upper graph. REAR 2 is a measurement of the occlusion effect
with the adjusted vents. The REIR curve in the upper graph is a measure-
ment of the difference between the two vent configurations.

6.5 Digital Hearing Aids

All digital aids can be tested, but some of the high-end models require a little
more thought and care; these aids have a “noise suppression” feature (also
known as “speech enhancement”). This noise suppression, not to be confused
with the automatic compression of AGC hearing aids, checks if the sound going
into the hearing aid is a continuous signal that could be regarded as noise. If
the aid decides that the sound is noise, it lowers the gain at the corresponding
frequencies. Conventional testing techniques, such as a pure-tone sweep or the
Composite signal, can cause the high-end digital aid to go into this noise reduc-
tion mode. This means that the gain or output you see on the analyzer’s display
will not necessarily reflect the normal response of the aid in speech.

6.5.1 Using Digital Speech

The Digital Speech signal was developed in order to test noise-reducing digital
hearing aids without fear of them going into noise suppression mode. It does
this by taking the standard Composite signal and interrupting it randomly. The
digital hearing aid responds to this modulated signal as it would response to
normal speech.

The advantage of Digital Speech is that the 7000 analyzer treats it just as anoth-
er signal source. You don’t have to test the digital hearing aid any differently
than you would test a normal analog hearing aid. Just choose Digital Speech
as your testing signal using the [F5] function key in one of the real-ear testing
screens.

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