Maico MA 42 Operation Manual page 25

Operation Manual MA 42
For bone conduction measurements the interaural attenuation is 0 to 15 dB.
Bone conduction crossover is therefore possible even with a slight difference
in hearing loss between ears.
To ensure that the patient will not experience crossover, mask the opposite
ear. Masking increases the hearing threshold of the opposite ear when
crossover is occurring. For bone conduction the masking signal is
automatically routed to the opposite output of the phones or inserts.
The masking is done with a noise signal which is transmitted by the
headphone. For pure tone audiometry a narrowband noise is used. This noise
changes its center frequency according to the frequency of the test signal.
Manual Masking
The masking is switched on by selecting the signal source as noise (11) or (15)
and then pressing the Stim button (8) on the side presenting the noise.
Note: Be cautious to set the noise to an appropriate level prior to selecting
Stim (8) and turning on the masking noise to the patient.
Once the threshold has been established with the introduction of noise, press
the Store button on either side of the instrument. The hearing threshold value
will be stored in the audiogram with the corresponding masking symbol.
The masking sound should be continuously presented for effective masking by
pressing the Stim button (2). You can interrupt or turn off the masking signal
by pressing the Stim button (2) again.
8100460 Rev.7 Ver.1 20 12/15