16
Testing FM Systems with FONIX 6500-CX Analyzers
1.3 Omni-directional: FM+ENV
This section contains a description of the different coupler measurements of omni-directional
FM systems when the client primarily uses the system with the environmental microphone
added to the FM signal (FM+ENV mode). These measurements are:
• Response of aid with 65 dB SPL signal at 1 kHz
• Response of FM transmitter/receiver with 65 dB SPL signal at 1 kHz
• Verify increase of FM transmitter/receiver when signal level is increased to 80 dB SPL.
• EHA65: typical electroacoustic response of the aid
• EFE80: typical electroacoustic response of the FM transmitter/receiver
• EEF65: typical electroacoustic response of environmental microphone
• EHA90: saturation electroacoustic response of the aid
• EFE90: saturation electroacoustic response of the FM transmitter/receiver
• EEF90: saturation electroacoustic response of environmental microphone
1.3.1 Single frequency output of omni-directional hearing aid in the sound chamber
1. Set up the hearing aid for testing as described in the hearing aid setup in Section
1.1.2. The FM transmitter should be off, and the hearing aid set to receive input from
the hearing aid microphone.
2. Press
[RESET].
3. Press [SINE/COMPOSITE] to put the analyzer in PURE TONE MODE.
4. If necessary, use [<, >] to adjust the frequency of the single tone signal to 1000 Hz.
Figure 1.3.1
Hearing aid output at 65 dB SPL at 1000 Hz