60 FONIX FP35 Hearing Aid Analyzer
3.2.2 Leveling Using the Reference Microphone
If your analyzer has the M300 two microphone setup, you can level using the probe
microphone as a reference microphone. If you choose to do this type of leveling,
you will need to level every time the hearing aid set up changes significantly
(e.g. you begin to test a different style or model of aid). This method is more
exact than the general purpose leveling described in the previous section and
performed at the factory. It is useful to note that for most practical purposes,
there is little difference between the results of these two methods of leveling.
1. Enter the Coupler Multicurve screen by pressing [F3] in the Opening screen.
2. Look in the middle of the right side of the screen. If it reads REF OFF, you
will need to turn on the reference microphone. To do this, press [MENU]
and use the arrow keys to turn the REF MIC selection ON, and press [EXIT]
to return to the Coupler Multicurve screen.
3. Set up the hearing aid that you are going to test. See Section 3.3 for details.
Make sure the hearing aid is off.
4. Place the hearing aid/microphone assembly in the sound chamber with the
hearing aid microphone at the reference point.
5. Attach a probe tube to the smaller reference (probe) microphone, and secure
the end of the probe tube with a bit of Fun-Tak so that the tip is right next to
the microphone of the hearing aid.
6. Position the microphone cables between the arrows on the speaker face. The
Velcro on the coupler will help secure the assembly in place. See Figure
3.2.2.
7. Close the chamber lid.
8. Make sure the environment is as quiet as possible.
9. Press [F5], followed by [START/STOP], to level the sound chamber.
10. Follow the instructions in Section 3.2.3 to save the leveling, if desired.
Figure 3.2.2—Leveling using the reference microphone
