Hearing Aid User Manual

Real-Ear Measurements 171
6.9.3.1 CROS
Unaided—Measurement of “good” ear
Set up the 7000 test system as follows.
• Reference microphone ON
• Sound field LEVELED
• Reference microphone over pinna
of bad ear
• Probe microphone inside unoc-
cluded ear canal of good ear
• Loudspeaker at 0º, 12 inches from
bridge of nose
Aided—Measurement of “good” ear
Same setup as above, except:
• Aid in place in good ear and set to user gain.
The difference curve, labeled “Insertion Gain” on the screen, shows the overall
benefit of inserting the hearing aid.
6.9.3.2 BI-CROS
Unaided—Measurement of “better” ear
Set up the 7000 test system as follows:
• Reference microphone ON
• Sound field LEVELED
• Unaided response CUSTOM
• Reference microphone over pinna of
bad ear
• Probe microphone inside unoccluded
ear canal of better ear
• Loudspeaker at 0º, 12 inches from
bridge of nose
Aided—Measurement of “better” ear
Same setup as above, except—
• Complete aid in place in better ear and set at use gain
• Both transmitters on
The difference curve, labeled “Insertion Gain” on the screen, shows the overall
benefit of inserting the hearing aid.
BETTER
EAR
REFERENCE MIC
PROBE MIC
12"
BAD
EAR
SPEAKER
REFERENCE MIC
PROBE MIC
12"
SPEAKER
GOOD
EAR
BAD
EAR