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Testing FM Systems with FONIX 6500-CX Analyzers
1.6.8 Test with FM system using a high-level input — EFE90
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 select a source level of 90 dB SPL.
4.
Press [START/STOP] to make the measurement.
5. CRV 2 is now the Electroacoustic FM Saturation Response or EFE90.
6.
Compare EHA90 (CRV 1) to EFE90 (CRV 2). See Figure 1.6.8. If EFE90 is greater
than 5 dB above EHA90, adjust the FM system to obtain a better match. As a last
resort, adjust the settings on the hearing aid. If this must be done, the teacher, par-
ents, and therapists must be made aware that when the FM system is used, the set-
tings on the hearing aid must be changed for optimum performances.
Figure 1.6.8
Comparison of EHA90 (CRV1), the hearing aid response at 90 dB
SPL with EFM90 (CRV2), the FM response at 90 dB SPL
