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C H A P T E R
6 :
6.5.3 PSQM Algorithm Properties
PSQM always simulates a listening test
simulated test as a
with those results that would have been obtained from subjects in a real
listening test, PSQM must know some parameters of that virtual listening
experiment. The following parameters must therefore be entered in the
algorithm properties dialog (see also Section 4.4.2):
The listening condition
loudspeakers, headphones or typical telephone handsets for listening.
The level of the background masking noise
virtual experiment "Hoth noise". Real life will always have background
noise that produces masking effects. Even in silent environments this noise
is in most cases higher than 30 dBA. This effect is modelled by adding
background Hoth noise to the reference as well as to the test signal.
The level
at which the signal is played to the subject in the virtual listening
test.
The upper frequency
measurement.
Figure 6.5 shows the settings as they are recommended by P.861 for signals
with an average active speech level of -26dBov (this is e.g. the setting for the
NTT speech database).
Figure 6.5: PSQM Algorithm properties as recommended by P.861
6.5.4 Diagram Types
In Chapter 4 the Section "Getting to Know the OPERA™ Framework"
shows how to select a measurement algorithm and how to start a measurement.
Once the measurement is performed, results should be displayed. For the
PSQM algorithm, there are seven diagram types (see Figure 6.6) available
that will be described in this section. If not otherwise mentioned, all diagrams
T E L E P H O N Y
B A N D
T E S T I N G
virtual
listening test. To obtain results that highly correlate
, indicating if the virtual experiment uses
, representing the upper frequency limit of the
124
V O I C E
Q U A L I T Y
. The following will reference that
that was present during the
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