Audioscan Verifit 2 - Manual (Page 67)

Verifit ® User's Guide Version 4.2 © June 2015
/sh/. They also may support phonemic analysis of hearing aid responses. They are not meant to replace current
verification protocols used to verify conventional hearing aid fittings, but are meant to supplement your
verification procedures, particularly in the cases of extended bandwidth and/or frequency lowering.
How were the stimuli created?
Instances of /s/ and /sh/ were identified within the ISTS passage, which is based on female speech, to create a
target spectrum per phoneme. A simulated version of "S" and "SH" was then created using shaped noise to
simulate the target spectrum for each phoneme. The resulting stimulus files are each 5 seconds long.
1. Verify the frequency shaping and output of the fitting without frequency lowering to ensure best audible
bandwidth of speech from gain & WDRC alone. The steps below have been developed with the DSL v5
target as the base fitting method.
2. Start the "S" stimulus at a presentation level of 65 dB SPL. Determine whether the stimulus is within the
listener’s auditory area. If not, complete the steps below.
3. Enable a frequency lowering signal processor. Start with the default frequency lowering setting. The "S" will
"loop", so you can keep it playing continuously while you fine tune the frequency lowering signal processor
as needed. Lower the "S" in frequency until it is audible.
4. Start the "SH" stimulus at a presentation level of 65 dB SPL. Determine whether it is audible, and also
whether it has some frequency separation from the "S" stimulus. If they are overlapping, the listener may
have difficulty perceiving them as two different speech sounds. Fine tune as needed.
(a) Exact target levels for individual phonemes are not yet established.
(b) Because the ''S'' and ''SH'' stimuli are much broader in frequency than a pure tone, some listeners may
detect the stimuli at levels that are near their pure tone thresholds.
5. Perform a listening check, considering whether the sound quality and distinction of "S" and "SH" in speech
are acceptable. At the time of fitting and follow up, consider the listener’s responses, therapist feedback, and/
or outcome measurements that provide insight into the perceived sound quality and ability to distinguish "S"
and "SH".
67