OPTICOM OPERA - V 3.5 User Manual page 199

PESQ
PESQ stands for "Perceptual Evaluation of Speech Quality" the new ITU standard P.862. At
the time PSQM was standardized as P.861, the scope of the standard was to assess speech
codecs, used primarily for mobile transmission, like GSM. VoIP was not yet a topic. The
requirements for measurement equipment have changed dramatically since then. As a
consequence, the ITU set up a working group to revise the P.861 standard and to cope with
the new demands arising from next generation networks like VoIP. Within these networks,
the measurement algorithm has to deal with much higher distortions than with GSM codecs,
but perhaps the most eminent factor is that the delay between the reference and the test
signal is no longer constant. PESQ combines the excellent psycho- acoustic and cognitive
model of PSQM+ with a time alignment algorithm adopted from PAMS, that handles varying
delays perfectly. PESQ is not designed for streaming applications, which is itís only
drawback. This is why it cannot fully replace PSQM+. With PSQM and PESQ there are now
two standards that cover the entire problem of measuring speech quality. See also
www.pesq.org.
PGAD
Post Gateway Answer Delay
POTS
Plain Old Telephony Service (often used to characterize the traditional analog telephone service).
PSQM
Perceptual Speech Quality Measure
Stands for \Perceptual Speech Quality Measure\", the perceptual measurement technique recommended
in ITU-T P.861. See also www.psqm.org."
Reference
Test excerpt, reproduced without the processing by a test object, used as a comparison basis for an
impairment test.
RSVP
Resource Reservation Protocol
SDG
According to ITU-R BS.1387, the analysis of the results from a subjective listening test is in general based
on the SDG (Subjective Difference Grade) defined as:
SDG = GradeSignal Under Test - GradeReference Signal
The SDG values should ideally range from 0 to -4, where 0 corresponds to an imperceptible impairment
and -4 to an impairment judged as very annoying.
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