Audioscan Verifit 2 - Manual (Page 110)

Verifit ® User's Guide Version 4.2 © June 2015
Test box directional procedure
To test directional function in the test chamber:
1. Mount the hearing aid to the 0.4cc wideband coupler (see Coupling the hearing instrument).
2. Position the hearing instrument in the test chamber as shown in 9.6: Directional ITE positioning or 9.7:
Directional BTE positioning.
3. Select [Directional] from the Test box column on the home menu.
4. Select Test 1, 2, 3 or 4. This presents test signals from front speaker and either the left or right speaker
depending on which ear has been selected. Two real-time curves appear on the screen - the heavier one is the
response to the front speaker signal and the lighter one the response to the appropriate ear speaker signal. For
a non-directional instrument, the two curves will be nearly identical. Setting the instrument for directional
operation should produce a separation of the curves.
5. On the Test control poster, select the Level window, then select a level from the drop-down list. For an
adaptive directional instrument, a stimulus level between 60 and 70 dB should cause the separation to change
over a 15 – 45 second period. For a noise-reducing instrument, both curves may change with time and
stimulus SPL.
6. Select [Speech S/N] within the Test control poster and select a signal to noise ratio from the list box (defaults
to 0 dB). A S/N ratio between 0 and 6 dB will usually induce directional performance after 15 – 45 seconds.
Optionally, select [Speech S/N] and select Off. This presents noise alternating between the front and
appropriate side speakers. Speech-adaptive directional instruments may appear to be non-directional if
[Speech S/N] is set to Off.
7. Click to capture curves or click to abort the test. Captured curves are labeled F (front speaker
response) and L (left speaker response) or R (right speaker response) followed by the test number (1 - 4).
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