Frye FONIX FP40D - Manual (Page 125)

Spectrum Analysis 117
Chapter 6: Spectrum Analysis
6.1 Spectrum Mode
This mode is only available on FP40 instruments that have the Real-Time/Composite Signal.
The FONIX FP40 can be used as a sound spectrum analyzer in either the coupler (test box) or real-
ear test modes. When the Spectrum Mode is selected, external sounds can be measured through the
microphones, or through a direct electrical connection, and displayed in an amplitude-vs-frequency
format.
6.2 Entering the Spectrum Mode
The FP40 must be in the “COMPOSITE MODE.”
1. Turn the AMPLITUDE control knob to the left (counter-clock wise) until the “RMS Source” is
“OFF.”
2. The “Status” information box should read “Spectrum Mode.”
6.3 Using the Spectrum Mode
You should find the following three suggested applications clinically helpful, interesting and fun.
A
PPLICATION
1: M
EASURING THE
“
OCCLUSION EFFECT
”
OF A HEARING AID
.
This simple procedure will help you measure the occlusion effect of the hearing aid wearer’s own
voice. The spectrum analysis mode will help you judge the sometimes uncomfortable feeling caused
by the occlusion effect of a hearing aid. You will be able to measure the effect and the improve-
ments made after venting adjustments have been made.
Suggested procedure:
1. Press F5 from the Main Coupler screen to enter the Probe Mode.
2. Use F2 to select SPL.
3. Use F7 to select a source type of COMPOSITE.
4. Use the AMPLITUDE knob to turn the source all the way OFF. This puts the analyzer in
Spectrum Analysis Mode.
5. Place the probe tube as close as possible to the eardrum. Marking the probe tube depth at
25-30 mm should accomplish this in an average adult ear canal. Position the client 12” from
speaker at a 45 degree angle.