A2.5 Free-field Warble Tones Calibration
A2.5.1 Entering Free Field Calibration Mode
Press OPTIONS and then the NEXT key to move through the menu
items and access the ‘Set freefield levels’ screen. Press the YES key.
Press QUIT and you are now presented with the freefield calibration
screen for Warble tones.
The audiometer will now output at 70dBHL from the Left channel.
As reference for the calibration of warble tone sound pressure levels, the
values from ISO 389-7, Table 1 are used (binaural, on-axis).
If a calibration of the speech channel has already been carried out:
Adjust the calibration level for the 1kHz, Left channel using the SIGNAL
control to reach the SPL level specified above as measured by the SLM
If a calibration of the speech channel is not required:
The output of the external amplifier should be set in order to achieve the
level specified above at 1000Hz (i.e. 72dBSPL) as measured by the SLM
with the audiometer set to 0dB compensation. The amplifier’s level control
should not then be changed.
When 1kHz, Left channel has been calibrated:
At every other frequency the adjustment should then be made as follows
to give the above values as measured by the SLM.
Change frequency using the Hz keys and then adjust the
calibration level for the new frequency using the SIGNAL control to
reach the correct level as measured by the SLM
Repeat the above until all frequencies have been calibrated for the
Left channel
To calibrate the Right channel (if required) press the RIGHT key (do
not change the amplifier’s volume control)
Adjust the calibration for all of the right channel frequencies (including
1000Hz) by using the Hz keys and the SIGNAL control as
described above
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