OPTICOM PESQ - DATASHEET 05-11-14 Datasheet

PESQ – Perceptual Evaluation
of Speech Quality
OPTICOM's PESQ (Perceptual Evaluation of
Speech Quality) provides accurate and repeat-
able estimates of speech quality degradation
occurring through e.g. a telephony network. It
compares the audio signal input to a network
with the corresponding (degraded) audio signal
output from the network. P.862 is based on the
earlier P.861 (PSQM) technology developed by
KPN Research extended to include a time align-
ment model.
Being already widely used in active testing in
both lab environments and in network test
Principle
The degraded signal and the reference signal
are individually level aligned and filtered with
the transfer characteristics of a receiving device
(handset). Basically two different filter functions
– a narrow band (IRS) filter and a wide band fil-
ter – are available and may be chosen depend-
ing on the preferred application. After that the
two signals are time aligned in order to com-
pensate for small time shifts that can occur in
e.g. Voice over IP networks due to delay and jit-
ter changes and coding.
In order to account for the distortions that are
actually perceived by a human listener the
model transforms the two aligned and filtered
signals from the time-amplitude domain into a
frequency-loudness domain (auditory transform).
Reference
signal
Level Input
align filter
System
under test
Level Input
align filter
Degraded
signal
PEVQ™, 3SQM™ and the OPTICOM logo are registered trademarks of OPTICOM GmbH; the 'single-sided speech quality measure' and
'the perceptual quality experts' are trademarks of OPTICOM GmbH. This information may be subject to change.
All brand and product names are trademarks and/or registered trademarks of their respective owners.
All rights reserved. Copyright © 2005 OPTICOM GmbH – www.opticom.de
equipment, OPTICOM's PESQ has achieved a
great reputation for its ease of use and its relia-
bility of its results while lowering the costs for
the measurements.
OPTICOM's PESQ is fully compliant to ITU-T
P.862.x covering the applicability to narrow
band as well as wide band audio signals.
OPTICOM who is the leading provider of signal
based perceptual measurement technologies
offers algorithms for voice, audio and video
quality measurements.
By subtracting the two signal representations
an estimate of the audible differences is
derived. The audible differences are accumulat-
ed over time while they are weighted different-
ly depending on whether a distortion was
added to the signal or if parts of the signal
were missing after the transmission (cognitive
model).
Finally after the analysis a single Mean Opinion
Score (MOS) is generated. The MOS is common-
ly used to describe the voice quality on a scale
from 1 (bad quality) to 5 (excellent quality).
Auditory
transform
Time
Disturbance
align and
processing
equalise
Auditory
transform
Re-align bad intervals
Prediction
of perceived
Cognitive
speech
modelling
quality
Identify bad
intervals
Voice
Quality Testing
OPTICOM Product Line:
Voice/Audio Quality
PESQ ITU-T P.862
3SQM ITU-T P.563
PSQM ITU-T P.861
ECHO
PEAQ ITU-T BS.1387
Video Quality
PEVQ
Network Quality
VQmon
Key Features:
• Perceptual analysis of
degradations in voice sig-
nals
• Well established, repeat-
able results
• Output score correlates
very well with subjective
MOS
• Automatic time alignment
capability
• Available as DLL/Library
and Source