DSL FP40 method - Frye Electronics

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DSL Method Using FP40/FP40-D
DSL WORKSHEET (GAIN)
Worksheet #1: Calculating Target 2 cc coupler gain values as a function of frequency
Threshold (dB HL)
Desired Real Ear
Aided Response
RECD values
Mic Effects*
Target coupler gain
(row 2-3-4)
Measured coupler
gain
Difference (row 5-6)
250 500 750 1000 1500 2000 3000 4000 6000
*Mic Location Effect values as a function of hearing aid type and audiometric frequency.
Frequency (Hz)
250 500 750 100 1500 2000 3000 4000 6000
BTE 0.5 1.2 0.9 0.3 2.5 4.1 2.8 3.7 1.6
ITE 0.5 1.8 2.0 1.5 -0.3 3.8 3.3 4.3 0.4
ITC 0.3 0 0.4 1.2 -1.9 2.1 3.5 6.4 -1.8
BODY AID 3.0 4.0 2.0 0 -4 -4 0 0 0
1. Enter the individual’s hearing Threshold measures as a function of frequency (row 1).
2. Using Table 2 determine the Desired Real Ear Aided Response as a function of frequency and real threshold
level. For example, if the audiometric threshold at 250 Hz is 30 dB HL, the desired real-ear aided
response (in gain) is 14 dB (row 2).
3. Enter the individual’s measured RECD values. If measured values cannot be obtained use estimated ageappropriate
RECD values as a function of frequency from Table 3(A) for ITE fittings and Table 3(B) for BTE
fittings (row 3).
4. Enter the appropriate mic location effect values as a function of hearing aid style (row 4).
5. To determine the Target 2 cc coupler gain values across frequencies, subtract the RECD and mic location
effect values from the desired real ear aided response values (row 2-3-4)
Using the frequency specific University of Western Ontario (UWO) LTASS values from Table 1, below, as a
guideline for test signal input levels, adjust the electroacoustic characteristics of the hearing aid in the
hearing aid test chamber to approximate the target 2 cc coupler values as a function of frequency. For
example, using a 50-dB stimulus level, adjust the volume control wheel to approximate the target 2 cc gain
at 2000 Hz. Using a 65-dB stimulus level, adjust the hearing aid tone control to approximate the target 2 cc
gain at 500 Hz. (Note: for linear and output compression hearing aids, set maximum output characteristics
prior to setting the hearing aid gain/frequency response characteristics).
TABLE 1. The one-third octave band levels (dB SPL) of the University of Western
Ontario long-term average speech spectrum for hearing aid fitting in children.
Frequency (Hz)
250 500 750 1000 1500 2000 3000 4000 6000
dB SPL 62.8 64.3 60.1 56.4 52.1 51.0 45.0 42.3 42.1
Permission is hereby granted to reproduce this worksheet.
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