Basic Sound Chamber Tests
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3.4.1 Signal Types
The following signal types are available:
DIGITAL SPEECH—A randomly interrupted composite signal designed to
mimic speech. This signal is for use with hearing aids with a “noise reduc-
tion” or “speech enhancing” feature that lowers the gain of the aid in the
presence of a continuous signal (such as the regular composite signal).
COMPOSITE—A continuous real-time, speech-weighted signal made up of
79 different frequencies. The composite signal gives you the advantage of
seeing how an aid responds to noise that more closely simulates speech,
and it lets you see immediately how the aid responds to any change in the
amplitude of the signal.
TONE LONG—A detailed frequency response curve that gives you infor-
mation on the amplification of 64 different pure-tone frequencies between
200 and 8000 Hz
TONE NORMAL—A detailed frequency response curve that gives you
information on the amplification of 43 different pure-tone frequencies
between 200 and 8000 Hz.
TONE FAST—A continuous pure-tone sweep that takes measurements at
16 different frequencies between 200 and 8000 Hz.
TONE SHORT—A single pure-tone sweep of 10 different frequencies.
3.4.2 Running a Test Curve
1. Press [MENU] to make any necessary selections. See Section 3.9 for details
on available menu selections.
2. Set up the aid in the sound chamber as described in Section 3.3 and level if
necessary.
3. Select signal type with [F5]. (Press [F5]. Use [
∨, ∧
] to select the desired sig-
nal type. Press [>] to complete the selection and close the pop-up menu.)
See Section 3.4.1 for details on signal types.
4. Press [START] to initiate the frequency sweep. If you are using the LONG,
NORMAL, or SHORT selections, the test will stop when the sweep is com-
plete. The COMPOSITE, DIG SPEECH, and FAST signals are continuous,
making it necessary to press [STOP] when you want the signal to stop.
5. Use [F2] to select the next curve to be measured.
6. Repeat steps 3-5 to take additional measurements.
Figure 3.4.2 shows a completed normal pure-tone sweep.
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