32
Testing FM Systems with FONIX 6500-CX Analyzers
6.
CRV 2 is now the Electroacoustic FM Response or EFM80.
7.
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. See Figure 1.5.2.77
1.5.3 Test aid alone with high-level input — EHA90
1.
Set up the hearing aid for testing in the sound field by following the directions
found in the hearing aid setup in Section 1.4.1. If you’ve already leveled the sound
field speaker, you can skip to step 6 in that section.
2.
Press [MENU] to enter the SPL Menu.
3.
Select PURE TONE for AIDED CURVE 1 and AIDED CURVE 2.
4.
Press [MENU] to return to the SPL Test Screen.
5. Press
[
∧
] to select CRV 1.
Figure 1.5.3
EHA90—the hearing aid response at 90 dB SPL
