108 FONIX FP35 Hearing Aid Analyzer
ment should be ignored. Choose ON to apply this rule. Choose OFF to ignore
this rule.
PREDELAY TIME—The delay after the first tone is presented and before the first
measurement is taken. See Section 2.4 for more information..
SHORT SETTLE—The time delay between the frequencies of pure-tone sweeps
and input/output curves.
LONG SETTLE—The time delay between the frequencies of three frequency
averages and distortion measurements.
PRINT LABEL— Status of the printing label. Choose ON or OFF.
PRINTER— Printer used for printouts. Choose INTERNAL to use the built-in
thermal printer. Choose EXTERNAL to use an attached laser or ink-jet printer.
4.4 ISI Testing
The ISI automated test sequence tests hearing aid to the ISI IS-10775-1984
standard. ISI is very similar to the IEC automated test sequence except that it
calculates the three-frequency HFA of the OSPL90 instead of the one-frequency
reference response, it tests the harmonic distortion at three different frequencies
instead of only one, and it provides an intermodulation distortion measurement
taken with tones at 1500 and 2500 Hz, referred to as the “difference frequency
distortion” (DF DIST).
Because the FP35 does not support battery current drain measurements, if the
1.0 volt testing part of the ISI standard needs to be performed, the user will
need to attach an external 1.0 volt battery simulator (or a weak battery) to the
hearing aid and run the ISI test sequence again, marking the results as being
done at 1.0 volts.
To enter the ISI screen, look at the function key labels above [F4] and [F5] in
the Opening screen. If one of them reads “ISI,” press it to enter the screen.
Otherwise, press and hold down [F4] or [F5] until a function key balloon menu
appears. Use the arrow keys to select ISI, and press [START/STOP] to enter the
screen.
See Section 4.2 for instructions on running the IEC test sequence. ISI testing is
performed in the same manner.
See Figure 4.4 for the following explanation of the ISI test results:
1. OSPL90: Response curve made at full-on gain at 90 dB SPL
2. FOG: Full-on gain response curve made at 50 or 60 dB SPL
3. RESP50: Response curve at 50 or 60 dB SPL at reference test gain
4. Aid type
