76 FONIX FP35 Hearing Aid Analyzer
Figure 3.7—Comparison of the responses with the MZ and HA-2 couplers
3.8 Advanced Testing
This section contains information of interest to the advanced user including
instructions for testing digital and directional aids, and procedures for reversing
and splitting the measurement microphones.
3.8.1 Testing Digital Hearing Aids
The FP35 seamlessly incorporates the testing of digital hearing aids into its nor-
mal testing procedures.
If you have the Composite/Digital Speech Option, just follow the steps outlined
in Section 3.4.1, choosing DIG SPCH in Step 7. This digital speech signal source
is an interrupted composite signal designed to imitate the rhythms of speech.
The aid will respond to the signal source as it would respond to actual speech.
See Appendix F for details about the digital speech signal.
If you do not have the Composite Option, put the aid into “test” mode via its
programming software and test normally. Some types of warbling pure-tone sig-
nals should not be used with digital hearing aids because the digital processing
delay of most digital aids interferes badly with warbling, creating inaccurate
measurement results. See Section 2.5.1.4 on warbling. Warbling is turned off by
default for coupler measurements.
