When the exact balance has been found, record the intensities presented to
the ears shown on the display. Thereafter, increase intensity in the right ear
by 10 dB using masking level control and then find the intensity in the left ear
at which the patient indicates that the tone was heard with the same
sensation. Record again the values shown on the display. Continue in this
way until maximum intensity on the audiometer has been reached, or until
the patient indicates that the presentation of the tone has reached the pain
level. Record the results from each test. In the absence of recruitment, the
difference between the two hearing level readouts will be constant during the
whole test. If the difference between the two readouts diminishes at
increased intensities, it is an indication of recruitment.
A typical example of recruitment in the left ear is shown in the table on the next
page.
Read Out 1 - Left
Read Out 2 - Right
40
20 (Thr10 dB)
50
30
57
40
65
50
72
60
75
70
80
80
Recruitment
As shown, the difference between the two ears becomes smaller and
smaller as the intensity is increased, and at 80 dB there is no difference at all.
The degree of recruitment will vary in different cases and may be more
marked than in the example given. In all cases, however, the recruitment
reduces the hearing span, i.e. from threshold to the uncomfortable loudness
level.
A normal ear has a wide hearing span and is able to perceive pure tones from
the normal threshold of 0 dB to the upper limit of the audiometer without
undue stress. The recruiting ear may only span 25 to 30 dB. Such a patient
may find tones 25 to 30 dB above threshold unbearably loud. The pure tone
test frequency to be used will depend upon the relative hearing losses of the
two ears, and should always be chosen so that there is a difference in hearing
loss of more than 20 dB. If there is no such difference, impedance audiometry
will, in most cases, be able to diagnose recruitment objectively.
Press
MENU
to exit the ABLB Test.
MENU
8.3 STENGER TEST
The Stenger Test setup is similar to a normal pure tone test setup with
Left+Right stimulus selected (Special, Stenger, Air, L + R, No Mask).
The display is as follows:
Freq.
Air
L:Tone
Air
R:Tone
1000 Hz
C/P/W
20 dB
20 dB
MIDIMATE 622 OPERATION MANUAL
8. Special Tests
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