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ReferenceSignal
Deviceunder test
Objectivemeasurement
method
Audioqualityestimate
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
PEVQNetwork Quality
VQmon
Voice
Quality TestingPEAQ PerceptualEvaluation of Audio
QualityOPTICOM's PEAQ (Perceptual Evaluation ofAudio Quality)
provides accurate and repeatableestimates of audio quality
degradation occur-ring through e.g. coding procedures. It
comparesthe audio signal input to a device under test(DUT) with the
corresponding (degraded) audiosignal output from that device on a
perceptualbasis.
Being already widely used in active testing inlab environments,
OPTICOM's PEAQ measure-ment has achieved a great reputation for
its
ease of use and its reliability of its results whileavoiding the
costs for expensive and time con-suming listening tests.
PEAQ is fully compliant to ITU-R BS.1387 cover-ing the
applicability to high quality audio sig-nals with sampling
frequencies of 44.1-48kHz.
OPTICOM who is the leading provider of signalbased perceptual
measurement technologiesand sole licenser for PEAQ offers
algorithms forvoice, audio and video quality measurements.
The intention of a measurement tool like PEAQis to evaluate the
audio quality of an audiodevice under test, e.g. an audio codec.
PEAQcompares the input and output audio signal ofthat device and
outputs a quality score that rep-resents the Basic Audio Quality of
the outputsignal and therefore also the quality of thedevice. The
comparison of the two signals takesonly perceptual differences into
account, whileimperceptible distortions are neglected. In order
to be able to distinguish between perceptibleand imperceptible
distortions PEAQ employs amultitude of perceptual measurement
conceptsusing different ear models from which differentsignal
representations are derived.
PEAQ in general comprises ear models basedon the fast Fourier
transform as well as on a fil-ter bank. The output values of the
models arebased partly on the masked threshold conceptand partly on
a comparison of internal represen-tations (also known as comparison
in thecochlear domain). In addition, it also yields out-
put values based on a comparison of linearspectra, which are not
processed by an earmodel.
The model outputs the partial loudness of non-linear
distortions, the partial loudness of lineardistortions (signal
components lost due to anunbalanced frequency response), a noise
tomask ratio, measures of alterations of temporalenvelopes, a
measure of harmonics in the errorsignal, a probability of error
detection, and theproportion of signal frames containing
audibledistortions. Selected output values are mappedto a single
quality indicator - the Objective
Difference Grade (ODG) - by an artificial neuralnetwork with one
hidden layer. The ODG indi-cates the measured basic audio quality
of thesignal under test on a continuous scale from -4(very annoying
impairment) to 0 (imperceptibleimpairment). Besides the ODG the
model out-puts a complementary quality value theDistortion Index
(DI). The DI is a quality indica-tor like the ODG except for its
higher sensitivitytowards very low signal qualities.
Key Features:
Perceptual analysis ofdegradations in audio sig-nals
Well established, repeat-able results
Output score correlatesvery well with subjectivetests
PEAQ Basic for real-timemeasurements
PEAQ Advance for moredetailed quality analysis
Principle
PEVQ, 3SQM and the OPTICOM logo are registered trademarks of
OPTICOM GmbH; the single-sided speech quality measure andthe
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
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Peripheralear model
(FFT based)
Peripheralear model
(Filterbank based)
Pre-processingof excitation patterns
Pre-processingof excitation patterns
Calculate modeloutput values
Calculate quality measure(artificial neural network)
Excitation patterns, specific loudness patterns,modulation
patterns, error signal
Excitation patterns, specific loudness patterns,modulation
patterns
Playback level Playback level
Input signals(Reference and signal under test)
Distortion index Objective difference grade
Specifications
Functionality
ITU-R BS.1387-1 Perceptual Evaluation ofAudio Quality, with
mapping to ODG scale(0=imperceptible, 4=very annoying)
Input
16 bit linear audio sampled at 44.1kHz and48kHz
Input audio files 10 to 20 seconds in length
Output
Objective Difference Grade (ODG)
Distortion Index (DI)
PEAQ Basic Model Output Values:Modulation changes, loudness of
distortions,Bandwidths of Signals, Frequency of audibledistortions,
Noise-to-mask ratio, Detection
probability, Harmonic structure of error
PEAQ Advanced Model Output Values:Loudness of distortion,
Changes in modula-tion, Linear distortions, Noise-to-mask
ratio,Harmonic structure of error
Complexity
PEAQ Basic real-time
PEAQ Advanced needs about four times thecomputational resources
as PEAQ Basic
Floating point library required
Platform
Windows
(others on request)
PEAQ - Perceptual Evaluation of Audio Quality
PEVQ, 3SQM and the OPTICOM logo are registered trademarks of
OPTICOM GmbH; the single-sided speech quality measure andthe
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
About OPTICOM
With PSQM, PESQ and PEAQ,OPTICOM GmbH, the pioneerin perceptual
quality testinghas been providing threeinternational
world-class
standards for voice and audioquality measurement sinceits
foundation in 1995. Withtheir new single-sidedspeech quality
measure3SQM, a joint developmentwith partners, the
perceptualexperts from Germany nowpresented their fourth
ITUstandard. At its 10th anniver-sary, the presentation of thenew
PEVQ video measureleverages the companyshuge experience towards
themultimedia testing domain.Recognized an industry refer-ence,
OPTICOMs OPERAvoice/audio quality test toolsare available to users
worldwide. And while specializedon OEM customers in particu-lar,
the directory of OEMlicensees today reads like theWho-is-Who of
theTelecoms industry. OPTICOMis a privately held companylocated in
Erlangen, Germany.
Sales Contacts:
OPTICOM GmbHNgelsbachstrae 3891052 Erlangen, GERMANYPhone:
+49-9131/5 3020-0Fax:
+49-9131/[email protected]
North America:
Telchemy Inc.
Phone +1-770-614-6944
JDSU - Acterna U.S.Phone +1-301 353 1560 2850
Europe, Latin America,Middle East & Africa,Asia Pacific, CIS
Countries:
JDSU - ActernaGermany GmbHPhone: +49-7121 86 2222
Through our distributor net-work, we are represented in
more than 80 countries. To findyour local sales office,
pleasecontact [email protected]
PEAQ comes in two versions: PEAQ Basic forreal-time measurements
and PEAQ Advancedfor detailed analysis in non-real-time
environ-ments. The main difference of the two modelslies in the
used ear models and the set of mod-ule output values to calculate a
final qualityscore.
Typical applications for PEAQ are: Assessmentof implementations,
perceptual quality line up,online monitoring, equipment or
connection sta-tus, codec identification, codec development,network
planning and aid to subjective assess-ment.
