Frye Electronics FONIX COLT Audiometer
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Make a note of the final hearing level and slope settings.
Selecting Full-on Gain
Tables 5.1 and 5.2 (below) are guidelines for fitting monaurally to ears having average canal
dimensions and normal middle-ear status. When fitting binaurally, slightly less gain may be
required for MCL. Also, ITE and Canal instruments may require slightly less high-frequency
gain.
Equivalent 2cc coupler gain curves for each slope setting of the Hearing Aid Simulator are
shown in Figure 5.1. These coupler curves assume a behind-the-ear hearing aid with a sealed
earmold. The gain for each slope has been adjusted in the Hearing Aid Simulator so that the
overall level of “audiometer speech noise” in a 6cc coupler is the same for each setting. This ap-
proximates equal loudness for each setting, in the normal ear.
Because of this built-in adjustment for equal loudness, the correction factors between “HL-at-
MCL” and “2cc-coupler full-on gain”, shown in Table 5.2, differ according to which slope set-
ting is used. Simply subtract the appropriate number in Table 5.2 from the “Hearing Level” dial
setting to get the suggested full-on gain* (or look up the suggested full-on gain in Table 5.1).
Table 5.2 Selecting Full-on Gain*
For this setting of the
Hearing Aid Simulator
Subtract this number from the
Hearing Level at final MCL
Off
45 dB
‡
6 dB
40 dB
‡
12 dB
40 dB
‡
18 dB
35 dB
‡
HFE
35 dB#
Large Vent or Open Canal Simulation for Ski-slope Losses
For “ski-slope” hearing losses, you will likely be using a very large vent, where low frequencies
are allowed to pass unamplified into the ear canal, while only the high frequencies are ampli-
fied. The flexible design of the Colt audiometer lets you simulate a large-vent fitting in the fol-
lowing way:
* The recommendations for full-on gain assume a reserve gain of 10 dB available to the patient at the volume control.
“Reserve gain” is the difference between the average “use gain” and the full-on gain. All values have been rounded to
the nearest 5 dB.
‡
For “Off”, “6dB”, “12dB”, and “18dB”, the full-on gain values are for the ANSI “High-Frequency-Aver-
age” (HFA) frequencies: 1000, 1600, and 2500 Hz.
# For “HFE”, the full-on gain values are for the ANSI “Special-Purpose-Average” (SPA) frequencies: 2000,
3150, and 5000 Hz. Use this setting only with the special “Ski-Slope” procedure, below.
