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D-0126050 rev 1 -
270+ Operating Manual
4.9.4.
USING LIVE SPEECH (EMIC.)
Users should be aware that there is a growing body of professional opinion that Live Voice speech audiometry
is generally not recommended. Select eMic. to present speech via live speech. The sound will then be
presented through the microphone of your external headset.
To ensure the speech present level is set correctly, check the VU meter is set to 0dB.
VU meter does not reach 0dB line
VU meter reaches 0dB line
Adjust the intensity level for the VU meter by using the Channel 2 rotary control and thereby adjust the
GAIN
level until the present level reaches 0dB. After the VU meter is set at 0dB speech testing can begin.
4.9.5.
USING RECORDED SPEECH (LINE)
For recorded speech audiometry, only material with a stated relationship with the calibration signal should be
used. Connect a CD, tape/MP3 player, or other sound source to the line in socket of the 270+.
Please note:
The audiometer line input is intended for connection to audio playback devices that are able
to output signals where the line level voltage amplitude is around 0.707Vrms. Using other types of output (i.e.
headphone sockets, laptop audio sockets) may result in a reduction of signal level. While some compensation
for a reduced level is possible using the audiometer, it is also possible to increase the signal levels of recorded
speech test material by using freely available PC software. Contact your distributor for details.
To ensure the correct present level is set, play the 1kHz calibration tone on the recorded material and adjust
the input signal such that the LEVEL dB bar graph reads 0dB; the headphone output measured in an IEC 318
ear simulator will now be 89dBSPL for a setting of 70dBHL.
The start and stop of the recorded speech material are controlled via the audio device itself, not the audiometer.
4.9.6.
MEASURING THE SRT SCORE
In order to measure the SRT (speech recognition score), a counter is available. Select
F1
(SRT) to activate
the counter.
For any given level of stimulus the display then shows the percentage correct alongside the total number of
responses.
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