37
Section 1: Coupler Tests of FM Systems
12. Press [START/STOP] to begin the measurement.
13. Press [START/STOP] once the measurement has stabilized. This curve is the
Electroacoustic Hearing Aid Response or EHA65. See Figure 1.6.4.
1.6.5 Test FM+ENV microphones with typical input to FM microphone — EFE80
1. Set up the FM system for testing according to the FM setup described in Section
1.4.2. The FM receiver should be set to receive FM+ENV. If you’ve already leveled
the sound field speaker, you can skip to step 5 in that section.
2. Use
[
∨
] to select CRV 2.
3
Use [<, >] to set the RMS source to 80 dB SPL.
4.
Press [START/STOP] to start the measurement.
5. Once the measurement stabilizes, press [START/STOP] again to stop the measure-
ment.
6.
CRV 2 is now the EFE80 or the Electroacoustic FM and Environmental Response
with 80 dB input to the FM microphone.
7.
Compare EHA65 (CRV 2) to EFE80 (CRV 1) to confirm that the desired FM advan-
tage is maintained over the 500 to 2000 Hz range. In general, that advantage should
be 7-10 dB. See Figure 1.6.5.
Figure 1.6.5
Comparison of EHA65 (CRV1), the hering aid response at 65 dB SPL
with EFM80 (CRV2), the FM response at 80 dB SPL
