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C H A P T E R
6 :
T E L E P H O N Y
T E S T I N G
First, there are no PSQM algorithm properties defined. This means that standard
values are used as recommended by ITU-T P.861. The recommended values
are:
• Listening Condition = IRS
• Hoth noise of 45 dB(SPL)
• Listening level of 101 dB(SPL)
• Upper frequency of 4 kHz..
After the Opera –Exec command following definitions are made: the PSQM
algorithm is selected and the input signals are defined, i.e. the first parameter of
the batch file is defined as Input 1, the second parameter as Input 2.
The signals are mapped: the left channel of input 1 is defined as the left channel
of the reference signal, the left channel of input 2 is defined as the left channel
of the test signal.
Then some settings that correspond to the signal preprocessing dialog are made.
First the Automatic delay compensation is switched on. The left channel is used
for this function and it is run in normal mode. In the Command Line Parameters
functionality there is only Normal Mode available, since the Snap Mode is only
useful for online measurements. However, online measurements cannot be
performed from a batch file.
The Static Gain Compensation function and the DC filter are switched on.
Finally, the third parameter of the batch file is defined as the output file. This file
contains the result values and the current measurement settings of the PSQM
measurement. The contained values will be tab-separated and can be imported
into any spreadsheet analysis program.
When the batch file has run successfully, have a look at the output file you have
specified. When the WAVE files have been used as proposed in this section –
PSQMRef.wav and PSQMTest.wav – the measurement results will correspond
with the following data:
•
OMOS-W0 = 3.35
•
OMOS-W2 = 3.46
•
OMOS-W4 = 3.30
•
OMOS+ = 3.60
B A N D
V O I C E
Q U A L I T Y
166
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