Frye FONIX FP40D - Manual (Page 132)

124 FONIX FP40 Portable Hearing Aid Analyzer
7.4 Testing
1. Use the amplitude knob to increase the level of the magnetic field. If you are using the
Composite signal, the amplitude will be displayed in the Status box. If you are using a pure-
tone signal, the amplitude is displayed in the lower right corner of the screen. When chang-
ing the field strength from 00 mA/M to 10 mA/M, the amplitude of the response should
increase by 10 dB if you are in an environment where it is possible to make valid telecoil
measurements. You are then above the background magnetic signal.
2. Use a signal strength of 10 mA/M to perform the telecoil test to the ANSI 87 standard. Use a
signal strength of 32 mA/M to perform the telecoil test to the ANSI 96 standard. The mea-
sured output will increase by 5 dB as you move from 10 to 18 to 32 to 56 mA/M, provided
the orientation of the hearing aid remains constant. These results are normal. Results that
vary from this norm may be due to environmental magnetic fields.
3. Press START/STOP to start a pure-tone sweep or the Composite signal measurement.
Notes
Use Noise Reduction when necessary to reduce the effects of stray magnetic fields.
Notice the position of the hearing aid that provides the highest amplitude. It may be useful to
explain to your client that his or her head may have to be in an unusual position to take full advan-
tage of the telecoil, or that it may be possible to turn the telephone receiver to increase the ampli-
tude of the signal.
Some users have both a telecoil and a separate sound chamber. For these users we supply a Y cord
so that both the sound chamber and the telecoil may be hooked up at the same time.