AmpliVox 260 - A2.6 Free-field Live Speech Calibration

Page 36 OM023-4 Amplivox 260 Operating Manual
A2.5 Free-field Warble Tones Calibration
A2.5.1 Entering Free Field Calibration Mode
 Press and hold the MENU key and then use the MENU SELECT keys
to move through the menu items and access ‘Set freefield level?’
 Press the YES key, release the MENU key 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).
Freq
[Hz]
125
250
500
750
1000
1500
2000
3000
4000
6000
8000
dB
SPL
92
81
74
72
72
70.5
68.5
64
63.5
72.5
81.5
If a calibration of the speech channel has already been carried out:
Adjust the calibration level for the 1kHz, Left channel using the SIGNAL
 keys 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  keys to
reach the correct level as measured by the SLM
 Repeat the above until all frequencies have been calibrated for the
Left channel