Frye FONIX FP40D - Manual (Page 108)

100 FONIX FP40 Portable Hearing Aid Analyzer
Figure 5.6.1.2B—Measured RECD
5.6.2 Performing coupler measurements to a DSL target
1. Enter your client’s thresholds and generate a target as described in Section 5.2. Make sure to
input your client’s age before generating the target.
2. Enter the Target 2-cc screen by pressing F7.
3. Decide whether you want to use the average RECD data to create the 2-cc target or the cli-
ent’s measured RECD. To measure the client’s RECD, follow the instructions found in Section
5.6.1. Make sure to unplug the insert earphone from the analyzer when done.
4. Check and make sure that the RESER is set to zero. This is at the bottom of the table in the
middle of the screen.
5. Press F6 to select desired amplitude of test signal.
6. The source type is shown on the screen. The source used is always the last source type you
used in the normal Probe screen.
7. Press F4 to choose the aid type.
8. Notice the comparison ratios (CR) displayed in the chart to the right of the target graph.
(DSL WDRC only) DSL authorities recommend fitting the aid at the average of the calculated
ratios. If there are large differences between the recommended ratios below 1500 Hz as com-
pared to those above 1500 Hz, a dual-channel aid would be preferable.
9. Press [START/STOP] to start measurement. If the signal type is composite or Digital Speech,
press [START/STOP] again when satisfied with measurement.
10. Press F6 to adjust the amplitude of the source if you are performing a DSL WDRC fitting.
Notice that the target changes as the source level changes. Perform the coupler measure-
ments at several different amplitudes to make sure that the AGC circuits of the hearing aid
are compressing properly with the measurement meeting the target at different amplitudes.
See Figure 5.6.2A.