17 8 FONIX FP35 Hearing Aid Analyzer
Custom Menu
Press [NEXT] from the Advanced Menu to enter the Custom Menu.
OUTPUT LIMIT—Level of output limiting, which shuts off the source when the
measured signal exceeds the limit set here. Choices are: OFF; 80-140 dB SPL.
This is usually used only for real-ear type measurements.
*WARBLE SOURCE—The warble rate in pure-tone signals. Warble is usually
used in sound field speaker measurements to reduce problems caused by stand-
ing waves. This is usually turned off for normal coupler measurements. See
Section 2.5.1.4 for more details.
*SIGNAL SKEW—The number of samples from when the signal source leaves
the speaker to when the FP35 analyzes it. See Section 2.5.1.5 for details.
SPEAKER—Speaker selection. INTERNAL selects the internal FP35 speaker.
EXTERNAL selects the external device (sound chamber or sound field speaker)
connected to the speaker jack. AUTO selects the internal speaker for sound
chamber measurements and the external speaker for real-ear measurements.
*OUTPUT JACK—Select which external source devices are enabled in the cou-
pler screens. SPEAKER enables only the speaker jack. MONO EAR enables only
the left channel of the earphone jack. STEREO EAR enables both channels of
the earphone jack. ALL ON enables the speaker jack and both channels of the
earphone jacks. See Section 2.5.5 for details.
LEVELING SOURCE—The amplitude used for leveling the speaker. This is use-
ful if you need to level with the chamber door open, and you don’t want to use
the loud default level of 90 dB SPL. Choose between 60 and 100 dB SPL.
*MICROPHONES—Special operational selections for your microphones.
Choices are NORMAL, REVERSE, and SPLIT. See Sections 3.8.4 and 3.8.5 for
more details.
*IMPULSE REJ—Status of impulse rejection, which rejects noise in the testing
environment. See Section 2.5.6.
*SPECTRUM WINDOW—When performing spectrum analysis of random sig-
nals such as speech or room noise, leave this ON. If you would like to perform
a spectrum analysis of a “phase synchronous” signal such as might be found in
one of our other instruments, turn this OFF. See Chapter 8 for more details.
*RMS ANALYSIS—Type of RMS measured. See Section 2.5.3.
*DIST 90 dB RULE—Harmonic distortion measurements are generally made
only when the source of the test signal is below 90 dB SPL. To measure har-
monic distortion at 90 dB SPL or higher, turn this rule OFF.
