FONIX® 7000 - Frye Electronics

Real-Ear Measurements 171
7. Test as usual. With the reference microphone disabled, it is even more critical
than usual that the patient not move after leveling and that the sound
field be undisturbed during testing.
6.8 Visible Speech
The Visible Speech screen, shown in Figure 6.8, is a special screen used for
performing real-ear measurements with live speech or other external source
types. Visible Speech was designed to demonstrate the real-time response of the
hearing aid to the speech signal, the average response of the aid over the time of
the test, and the minimum and maximum amplitudes of each frequency. These
measurements can be compared to the patient’s thresholds, uncomfortable levels,
real-ear target(s), and the long term average speech spectrum.
The Speech Intelligibility Index (SII) is calculated for each test. In general
terms, SII represents an indexed value in the range 0-100 representing the proportion
of all cues carried in verbal speech that are available to a particular
listener. See Section 6.8.5 for more technical details on SII and how it is calculated
on the 7000 Hearing Aid Test System.
When first entering the Visible Speech screen (Figure 6.8), the following is displayed:
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Shaded areas below and above the patient’s patient’s threshold and uncomfortable
values, respectively. The non-shaded area in the center of the graph
represents that patient’s dynamic range of hearing.
L, M, H dotted lines indicating the real-ear prescriptive targets at 50, 65, and
80 dB SPL. When NAL-NL1 or MOD NAL is not the selected fitting rule,
only the M target (65 dB SPL) will be displayed.
l, m, h dotted lines indicating the region of average unamplified speech.
These lines are called collectively the LTASS (long term average speech
spectrum). They can be used as a comparison against the amplified speech
response.