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Workshop on Wideband Speech Quality in Terminals and Networks: Assessment and Prediction
Future work on objective speech quality
measurements in ITU-T
Jens Berger
SwissQual AG, Switzerland
[email protected]
Workshop on Wideband Speech Quality in Terminals and Networks:
Assessment and Prediction
8th and 9th June 2004 - Mainz, Germany
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SwissQual AG – Your QoS Partner
Workshop on Wideband Speech Quality in Terminals and Networks: Assessment and Prediction
Structure
 History in ITU-T / CCITT
 Current Work – Listening Quality
 New Aspects in the Coming Study Period of ITU-T
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SwissQual AG – Your QoS Partner
Workshop on Wideband Speech Quality in Terminals and Networks: Assessment and Prediction
History in ITU-T / CCITT
1981-1984
Models for predicting transmission quality from objective measurements
Q7/XII
Non-linear distortion of telephone apparatus
Q13/XII
Models for predicting transmission quality from objective measurements
Q7/XII
Non-linear distortion of telephone apparatus
Q13/XII
Models for predicting transmission quality from objective measurements
Q7/XII
Methods for the evaluation of non-linear distortion
Q13/XII
1993-1996
Methods for measuring and modeling the effects of non-linear processes on
the speech quality of transmission systems
Q13/XII
1996-2000
Objective measurement of speech quality under conditions of non-linear
processing
Q13/12
1996-2004
Objective measurement of speech quality under conditions of non-linear
and time varying processing
Q9/12
2005-2008
Perceptual-based objective methods for voice, audio and visual quality
measurements in telecommunication services
1985-1988
1988-1992
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SwissQual AG – Your QoS Partner
Workshop on Wideband Speech Quality in Terminals and Networks: Assessment and Prediction
History in ITU-T / CCITT
Before 1990:
 ‘classical’ measurements of transmission / terminal characteristics
 early spectral- / cepstral-based measures
1996: P.861 ‘PSQM’

1st psychoacoustic based measure
for predicting listening Quality
Only ‚Core-Model‘ (no gain-/time-alignment)
2001: P.862 ‘PESQ’

Replaced P.861
Complete method incl. time-/gain-alignement
2004: P.563

1st single ended model for LQ assessments
Still Open

Listening Quality for Wideband speech

Listening Quality at Acoustical Interfaces
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SwissQual AG – Your QoS Partner
Workshop on Wideband Speech Quality in Terminals and Networks: Assessment and Prediction
Current Focus – Listening Quality
Main progression within the last few years:
Acceptance of psycho-acoustic based measures
modelling results of auditory tests on subjective
scales
but
a) Restriction to Listening Quality
b) Only applicable on narrow-band voice telephony
services
c) Serving only ‘electrical’ interfaces
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SwissQual AG – Your QoS Partner
Workshop on Wideband Speech Quality in Terminals and Networks: Assessment and Prediction
Work program starting 2005
Ongoing activities of former question 9/12
 Wide-band speech (listening) quality
 Listening quality at acoustical interfaces
and extensions to
 Audio- and noise-signals over telephone
channels
 Audio-visual aspects
 Talking quality and relations to conversational
quality
but
 Restriction to perceptual based models only
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SwissQual AG – Your QoS Partner
Workshop on Wideband Speech Quality in Terminals and Networks: Assessment and Prediction
Work program starting 2005
Principle concept:
Objective measures model specific subjective
(auditory) test scenarios and predict their
results on a similar scale.
Consequence:
A subjective test scenario has to be defined and
established before the corresponding objective
model can be developed.
Experience:
The better the auditory tests are defined and the
stronger their requirements are the more
accurate the predicted results will be.
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SwissQual AG – Your QoS Partner
Workshop on Wideband Speech Quality in Terminals and Networks: Assessment and Prediction
Wide-band speech scenarios
Current status:

Proposal from BT and KPN to extend P.862
(COM-12/D180, Feb. 2001)

Several studies from NTT in 2004 analyze
pro’s and con’s of this proposal

Awaiting advanced solutions for initial meeting in 2005
Open points:

Corresponding auditory tests (pure wide-band, mixed
with narrow band, which ratio?, which terminal(s)?)

What about ‘half-wideband’ (e.g. 200-5000Hz)?

Wider influence on terminal characteristics. Is wide-band
speech analysis useful without acoustical interfaces?
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SwissQual AG – Your QoS Partner
Workshop on Wideband Speech Quality in Terminals and Networks: Assessment and Prediction
Acoustical interfaces
Current status:

Work item P.AAM currently stopped because
disagreement on test scenarios to be served by the
approach.

Awaiting precise definitions about the scope and the
expected applications of the model
Open points:

Corresponding auditory tests for noise at listener side

Handling of handsfree in auditory tests (pure handsfree
or mixed with handset)

Handling of different terminals (mix of monotic and
diotic, influence of loss of acoustical coupling to real
environment?)
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SwissQual AG – Your QoS Partner
Workshop on Wideband Speech Quality in Terminals and Networks: Assessment and Prediction
Talking Quality
Current status:

Proposal from KPN for an perceptual based model
(COM-12/10, Nov. 2000; COM-12/D089, Jan. 2003)
Open points:

The subjective test procedure is neither defined nor
established

Current proposal does not consider real terminals

Extension to the acoustical interface is needed
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SwissQual AG – Your QoS Partner
Workshop on Wideband Speech Quality in Terminals and Networks: Assessment and Prediction
Audio- and noise-signals
Current status:

New action points
First steps: Music over telephone channels:

Applicability of ITU-R Recommendations?

Modifications on speech quality approaches sufficient?
First steps: Noise handling / Noise reduction

Starting point: P.835 describes the subjective test

Impact on clean speech could be handled by P.862 / P.AAM

Improvement / degradation of noisy speech could be handled by
framing of listening quality models

Quality of residual noise is an open point, an ‘Annoyance model’ is
needed
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SwissQual AG – Your QoS Partner
Workshop on Wideband Speech Quality in Terminals and Networks: Assessment and Prediction
Audio-visual quality assessment
Current status:

New action point

Audio-visual quality aspects in telecommunication
scenarios (lower bitrate, small image sizes) are
interesting for SG12

Initiating contribution (COM-12/D180, Feb. 2001)

Cooperation with SG9 and VQEG

Joint Rapporteur’s Group on Multi-Media Quality
Assessment is already established

Drafting of testplans
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SwissQual AG – Your QoS Partner
Workshop on Wideband Speech Quality in Terminals and Networks: Assessment and Prediction
Structuring of work
To be discussed in ITU-T:

Is a Recommendation / Appendix for wideband speech
assessment at electrical interfaces a migration step to a
more complete solution only?

How should the Recommendation(s) for measurements at
the acoustical interfaces be structured?

Inclusion of wide-band?

Separation of handsfree (separate model or only ‘switch’)?

Handling of binaural signals compared to classical handset?

Two / four separate models corresponding to the combinations of
interfaces ?

electrical – electrical

acoustical – electrical

electrical – acoustical

acoustical – acoustical
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SwissQual AG – Your QoS Partner
Workshop on Wideband Speech Quality in Terminals and Networks: Assessment and Prediction
Thank you for your attention!
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SwissQual AG – Your QoS Partner