Furthermore, you will find certain cases where the discrimination
percentage is less when a certain intensity is exceeded. The discrimination
percentages at different intensities are normally entered on a special speech
audiogram which graphically shows the ratio between the intensity and the
discrimination percentage.
Discrimination
Percentage
Set hearing level so that the patient just hears the words above threshold
level, thereafter present the complete word lists and observe the
discrimination percentage. Increase the intensity 10 dB and present the new
word lists and observe again the discrimination percentage. Continue in this
way until the maximum intensity of the audiometer is reached. If the patient
feels uncomfortable when presented with the higher intensity, the
measurements will probably have to stop at an intensity lower than the
maximum. By entering the results in the audiogram form you can read which
intensities give the greatest discrimination percentage. The discrimination
percentage can also be expressed as discrimination loss. This is simply the
difference between maximum possible discrimination percentage of 100
and the discrimination found. For example, if the patient has discrimination
percentage of about 75, he is said to have a discrimination loss of 100-75 =
25%.
7.3 SPEECH AUDIOMETRY WITH LIVE VOICE
Live voice examinations can only be carried out when the audiometer is used
in connection with a sound room, so that the patient cannot hear the
Audiologist's voice directly. With Audiologist and patient in the same room,
especially in examinations of patients with normal or almost normal hearing,
false results would be obtained.
Using a tape recorder to present word lists gives the advantage of always
presenting the same program for the patient, even if there is a short or longer
interval of time between the examinations. If live voice is used, there is the
risk that it is not the same investigator each time and this can influence the
results. However, the standardization of recorded tests has the disadvant-
age of lacking the flexibility of live voice testing, which enables the
Audiologist to better fit the test to the patient's individual needs.
If a sound room is not used, varying background noise levels can also
influence the results greatly. Speech audiometry, however, can be carried
out if you have a comparatively quiet room and the audiometer is equipped
with ME 70 noise-excluding headset. Either one or both channels can be
used for speech audiometry.
7.3.1 LIVE VOICE THRESHOLD MEASUREMENTS
Select the following setup: Speech, Air, Left, Micr., No Mask.
This gives the following display:
-Speech- Air
L:Micr
-Test-
20 dB
MIDIMATE 622 OPERATION MANUAL
7. Speech Audiometry
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