Psqm Or Pesq, Which One Shall I Use - OPTICOM OPERA - V 3.5 User Manual

C H A P T E R 6 :
As depicted in Figure 6.2, the quality of the coded speech is judged on the
basis of differences in the internal representation. This difference is used for the
calculation of the noise disturbance as a function of time and frequency. In
PSQM, the average noise disturbance is directly related to the quality of coded
speech.
Besides perceptual modelling, the PSQM method also uses cognitive modelling
in order to achieve high correlation between subjective and objective
measurements [ITUT861]. The result is the estimated quality of the received
signal.
Figure 6.2: Block diagram of the basic model of the PSQM algorithm [ITUT861]

6.4 PSQM or PESQ, which one shall I use?

Since there are two speech quality algorithms available as ITU
recommendations now, the user has to decide which one to use. This decision
however can be based on some very simple rules:
•
Whenever possible use PESQ. It is significantly better than PSQM.
•
If PESQ cannot be used for any reason, use PSQM, but take care of varying
delays.
•
The only reasons why the use of PSQM could be required are, to perform
online measurements, to compare your results to older measurements or simply
that a PESQ license for your OPERA system has not yet been ordered.
•
When using PSQM for any of these reasons, look carefully at the time
alignment. Although this is not a real issue with conventional PSTNs, it is a
significant problem on packet based networks. In these networks usually
varying delays are observed. To compensate for these varying delays, switch
OPERA's delay tracking option on.
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