13
Section 1: Coupler Tests of FM Systems
5. If you have a client with a mild to moderate hearing loss (less than 80 dB HL), the
output of the two curves should be within 5 dB of each other. If you have a client
with a severe to profound loss (greater than 80 dB HL), the output of EFM80 should
be 7-10 dB higher than the output of EHA65.
If you have to adjust the system to obtain a better result, first adjust the FM receiver
volume control if possible. When using FM systems coupled to personal hearing
aids adjust the settings on the hearing aid as a final step if necessary. If this must be
done, the teacher, parents, and therapists must be made aware that when the FM
system is used, the settings on the hearing aid must be changed for optimum per-
formances.
1.2.3 Test aid alone with high-level input — EHA90
1. Turn off the FM signal, and set up the hearing aid for testing as described in the
hearing aid setup in Section 1.1.2.
2. Press [SINE/COMPOSITE] button to enter Pure Tone Mode. The analyzer will auto-
matically set itself to a signal level of 90 dB SPL.
3.
Press [START] to begin the pure-tone sweep. The response will be stored in the
Multi-Curve stack when the measurement is complete. For instruments without the
Multi-Curve option, press [CRT] to print a hardcopy.
Figure 1.2.3
EHA90—hearing aid response at 90 dB SPL
4.
This response will be referred to as the Electroacoustic Hearing Aid Saturation
Response or EHA90. See Figure 1.2.3.
