P K A 8 7 O p e r a t i o n a l M a n u a l
Page 27
3.7.7 Manual Air Conduction Testing
Air conduction audiometry is used to establish a hearing threshold at different
frequencies. The test can specify the AC loss but gives no information regarding any
abnormality in the conductive mechanism or sensor neural mechanism.
3.7.8 Headphone Placement
Remove eyeglasses and earrings if possible and position the headphones over the
top of the head. Place the rubber cushions so that the diaphragms are aimed directly
at the opening of the ear canal. Pull the yokes of the earphones to adjust the fitting. If
the cushions are not tight on the ears, the test result will show false results at lower
frequencies.
3.7.9 Background Noise
Background noise can give false test results, especially at lower frequencies. The
Headphone can be used with Audiocups type V3 for reducing Background Noise.
3.7.10 Instruction to Subject
Prior to threshold testing the following instructions should be given to the test
subject: “You will now hear different tones at different intensities. Please press the
response button every time you hear the tone and release the button when you do
not hear the tone”.
3.7.11 Familiarization
Start with the subject‟s better ear at 1000 Hz. The tone should be presented at 40dB
to the test ear, which should be sufficient enough to evoke a clear response from the
subject. Then present a tone which is completely attenuated. If the subject does not
response to a tone at 40dB, present tones 10dB higher until a response occurs.
Then reduce the tone level by 20dB. In either case gradually increase the level until
a response occurs. Repeat the tone presentation at the same level. If the responses
are consistent, the familiarization is completed. If not, it should be repeated.
