SIST-V ETSI/EG 202 396-3 V1.3.0:2011

SLOVENSKI STANDARD
SIST-V ETSI/EG 202 396-3 V1.3.0:2011
01-junij-2011
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Speech and multimedia Transmission Quality (STQ) - Speech Quality performance in the

presence of background noise - Part 3: Background noise transmission - Objective test

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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Intellectual Property Rights ................................................................................................................................ 5

Foreword ............................................................................................................................................................. 5

1 Scope ........................................................................................................................................................ 6

2 References ................................................................................................................................................ 6

2.1 Normative references ......................................................................................................................................... 6

2.2 Informative references ........................................................................................................................................ 7

3 Abbreviations ........................................................................................................................................... 8

4 Speech signals to be used ......................................................................................................................... 9

5 Selection of the data within the scope of the wideband objective model: Experts evaluation ................. 9

5.1 Selection process ................................................................................................................................................ 9

5.2 Results .............................................................................................................................................................. 10

5.3 French database ................................................................................................................................................ 10

5.4 Czech database ................................................................................................................................................. 10

5.5 General differences between the databases ...................................................................................................... 12

6 Description of the wideband objective test method ............................................................................... 16

6.1 Introduction ...................................................................................................................................................... 16

6.2 Speech sample preparation and nomenclature .................................................................................................. 17

6.2.1 Speech sample preparation ......................................................................................................................... 17

6.2.2 Nomenclature .............................................................................................................................................. 19

6.3 Principles of Relative Approach and Δ Relative Approach .............................................................................. 20

6.4 Objective N-MOS............................................................................................................................................. 23

6.4.1 Introduction................................................................................................................................................. 23

6.4.2 Description of N-MOS algorithm ............................................................................................................... 24

6.4.3 Comparing subjective and objective N-MOS results .................................................................................. 27

6.5 Objective S-MOS ............................................................................................................................................. 28

6.5.1 Introduction................................................................................................................................................. 28

6.5.2 Description of S-MOS Algorithm ............................................................................................................... 28

6.5.3 Comparing Subjective and Objective S-MOS Results ................................................................................ 32

6.6 Objective G-MOS............................................................................................................................................. 32

6.6.1 Description of G-MOS Algorithm .............................................................................................................. 32

6.6.2 Comparing subjective and objective G-MOS results .................................................................................. 33

6.7 Comparison of the objective method results for Czech and French samples ................................................... 34

6.8 Language Dependent Robustness of G-MOS ................................................................................................... 38

7 Validation of the Wideband Objective Test Method .............................................................................. 40

7.1 Introduction ...................................................................................................................................................... 40

7.2 All conditions results analysis .......................................................................................................................... 42

7.2.1 Comparing subjective and objective N-MOS results .................................................................................. 42

7.2.2 Comparing subjective and objective S-MOS results .................................................................................. 43

7.2.3 Comparing Subjective and Objective G-MOS Results ............................................................................... 43

7.3 French Conditions Results Analysed ................................................................................................................ 44

7.3.1 Comparing Subjective and Objective N-MOS Results ............................................................................... 44

7.3.2 Comparing Subjective and Objective S-MOS Results ................................................................................ 45

7.3.3 Comparing subjective and objective G-MOS results .................................................................................. 45

7.4 Czech conditions results analysis ..................................................................................................................... 46

7.4.1 Comparing subjective and objective N-MOS results .................................................................................. 46

7.4.2 Comparing subjective and objective S-MOS results .................................................................................. 47

7.4.3 Comparing Subjective and Objective G-MOS Results ............................................................................... 47

8 Objective Model for Narrowband Applications ..................................................................................... 48

8.1 File pre-processing ........................................................................................................................................... 48

8.2 Adaptation of the Calculations ......................................................................................................................... 49

Annex A: Detailed post evaluation of listening test results ................................................................ 51

Annex B: Results of PESQ and TOSQA2001 - Analysis of EG 202 396-2 database ........................ 56

Annex C: Comparison of objective MOS versus auditory MOS for the All Data of Training

Period ..................................................................................................................................... 63

Annex D: Comparison of objective MOS versus auditory MOS for the Data not used during

the Training Period ............................................................................................................... 65

Annex E: Regression Coefficients for Czech data ............................................................................... 67

Annex F: Detailed STF 294 subjective and objective validation test results .................................... 68

Annex G: Void ........................................................................................................................................ 72

Adaptation, Training and Validation .................................................................................. 73

Annex I: Validation results of the modified EG 202 396-3 objective speech quality model for

narrowband data ................................................................................................................... 77

I.1 Introduction ............................................................................................................................................ 77

I.2 Description of the Databases .................................................................................................................. 77

I.3 Collection of the subjective scores ......................................................................................................... 78

I.4 Differences: HEAD acoustics training database vs. France Telecom validation databases ................... 80

I.5 Results .................................................................................................................................................... 81

I.6 Unmapped Results .................................................................................................................................. 81

I.7 Mapped Results ...................................................................................................................................... 84

I.7.1 Use of mapping functions ................................................................................................................................. 84

I.8 Conclusions ............................................................................................................................................ 90

History .............................................................................................................................................................. 92

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This ETSI Guide (EG) has been produced by ETSI Technical Committee Speech and multimedia Transmission Quality

The present document is a deliverable of ETSI Specialized Task Force (STF) 294 entitled: "Improving the quality of

eEurope wideband speech applications by developing a performance testing and evaluation methodology for

The present document is part 3 of a multi-part deliverable covering Speech and multimedia Transmission Quality

(STQ); speech quality performance in the presence of background noise, as identified below:

Part 2: "Background noise transmission - Network simulation - Subjective test database and results";

The present document aims to identify and define testing methodologies which can be used to objectively evaluate the

performance of narrowband and wideband terminals and systems for speech communication in the presence of

Background noise is a problem in mostly all situations and conditions and need to be taken into account in both,

terminals and networks. The present document provides information about the testing methods applicable to objectively

evaluate the speech quality in the presence of background noise. The present document includes:

• The description of the experts post evaluation process chosen to select the subjective test data being within the

• The results of the performance evaluation of the currently existing methods described in ITU-T

Recommendation P.862 [i.16], [i.17] and in TOSQA2001 [i.19] which is chosen for the evaluation of terminals

in the framework of ETSI VoIP speech quality test events [i.8], [i.9], [i.10] and [i.11].

• The method which is applicable to objectively determine the different parameters influencing the speech

- EG 202 396-1 [i.1] which describes a recording and reproduction setup for realistic simulation of

background noise scenarios in lab-type environments for the performance evaluation of terminals and

- EG 202 396-2 [i.2] which describes the simulation of network impairments and how to simulate realistic

transmission network scenarios and which contains the methodology and results of the subjective scoring

- French speech sentences as defined in ITU-T Recommendation P.501 [i.13] for wideband and English

References are either specific (identified by date of publication and/or edition number or version number) or

non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the

Referenced documents which are not found to be publicly available in the expected location might be found at

NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee

The following referenced documents are necessary for the application of the present document.

The following referenced documents are not necessary for the application of the present document but they assist the

[i.1] ETSI EG 202 396-1: "Speech and multimedia Transmission Quality (STQ); Speech quality

performance in the presence of background noise; Part 1: Background noise simulation technique

[i.2] ETSI EG 202 396-2: "Speech Processing, Transmission and Quality Aspects (STQ); Speech

Quality performance in the presence of background noise; Part 2: Background Noise Transmission

[i.3] ITU-T Recommendation P.835: "Subjective test methodology for evaluating speech

[i.4] ITU-T Recommendation P.800: "Methods for subjective determination of transmission quality".

[i.5] ITU-T Recommendation P.831: "Subjective performance evaluation of network echo cancellers".

[i.6] Genuit, K.: "Objective Evaluation of Acoustic Quality Based on a Relative Approach", InterNoise

[i.7] ITU-T Recommendation SG 12 Contribution 34: "Evaluation of the quality of background noise

[i.8] ETSI 2nd Speech Quality Test Event: "Anonymized Test Report", ETSI Plugtests, HEAD

NOTE: Available at: http://www.etsi.org/WebSite/OurServices/Plugtests/History.aspx.

[i.9] ETSI 3rd Speech Quality Test Event: "Anonymized Test Report "IP Gateways"".

NOTE: Available at: http://www.etsi.org/WebSite/OurServices/Plugtests/History.aspx.

[i.11] ETSI 4th Speech Quality Test Event: "Anonymized Test Report "IP Gateways and IP Phones"".

NOTE: Available at: http://www.etsi.org/WebSite/OurServices/Plugtests/History.aspx.

[i.12] F. Kettler, H.W. Gierlich, F. Rosenberger: "Application of the Relative Approach to Optimize

[i.14] R. Sottek, K. Genuit: "Models of Signal Processing in human hearing", International Journal of

[i.15] SAE International - Document 2005-01-2513: "Tools and Methods for Product Sound Design of

[i.16] ITU-T Recommendation P.862: "Perceptual evaluation of speech quality (PESQ): An objective

method for end-to-end speech quality assessment of narrowband telephone networks and speech

[i.17] ITU-T Recommendation P.862.1: "Mapping function for transforming P.862 raw result scores to

[i.18] ITU-T Recommendation P.862.2: "Wideband extension to Recommendation P.862 for the

[i.19] ITU-T Recommendation SG 12 Contribution 19: "Results of objective speech quality assessment

[i.21] ITU-T Recommendation G.722.2: "Wideband coding of speech at around 16 kbit/s using Adaptive

[i.22] ITU-T Recommendation P.56: "Objective measurement of active speech level".

[i.25] R.A. Fisher: "Statistical methods and scientific inference", Oliver and Boyd, 1956.

[i.26] M. Kendall: "Rank correlation methods", Charles Griffin & Company Limited, 1948.

[i.27] Sottek, R.: "Modelle zur Signalverarbeitung im menschlichen Gehör, PHD thesis RWTH Aachen,

[i.28] ITU-T Recommendation P.830: "Subjective performance assessment of telephone-band and

[i.29] ITU-T contribution COM 12-117, Study Period 1997-2000: "Report of the question 13/12

[i.30] ANSI S1.1-1986 (ASA 65-1986), "Specifications for Octave-Band and Fractional-Octave-Band

As with any objective model, the prediction of speech quality depends on the conditions under which the model was

tested and validated (see clauses 6.1 and 8). This dependency also applies to the speech material used in conjunction

The wideband version of the model uses French speech sentences. The near end speech signal (clean speech signal)

consists of 8 sentences of speech (2 male and 2 female talkers, 2 sentences each). Appropriate speech samples can be

The narrowband version of the model uses English speech sentences. The near end speech signal (clean speech signal)

consists of 8 sentences of speech (2 male and 2 female talkers, 2 sentences each). Appropriate speech samples can be

The aim of the selection process was to identify those data in the databases described in EG 202 396-2 [i.2] which are

consistent with the scope of the objective models to be studied within the present document.

The experts were selected on the based on the definition found in e.g. ITU-T Recommendation P.831 [i.5]: experts are

experienced in subjective testing. Experts are able to describe an auditory event in detail and are able to separate

different events based on specific impairments. They are able to describe their subjective impressions in detail. They

have a background in technical implementations of noise reduction systems and transmission impairments and do have

detailed knowledge of the influence of particular implementations on subjective quality.

Their task was to select the relevant conditions within the scope of the model to be developed. Therefore they had to

verify the consistency of the data with respect to the following selection criteria:

1) Artefacts others than the ones which should have been produced by the signal processing described in [i.2]

e.g. due to the additional amplification required in order to provide a listening level of 79 dB SPL.

2) Inconsistencies within one condition due to the selection of the individual speech samples from the database

3) Inconsistencies within one condition due to statistical variation of the signal processing described in [i.2]

4) Inconsistencies due to ITU-T Recommendation P.56 [i.22] level adjustment process chosen for the complete

5) Impact of the different listening levels used in the two databases - the French and the Czech database.

As a result of the experts listening test a set of data was selected which is used for the development of the objective

In the selection process five expert listeners (not native French/Czech speakers) were involved. Their task was not to

produce new judgements, but to check all the samples in the database with respect to the possible artefacts described

A playback system with calibrated headphones was used for the test. The headphones used were Sennheiser HD 600

connected to the HEAD acoustics playback system HPS V. The equalization provided by the headphone manufacturer

All samples could be heard by the experts as often as required in order to get final agreement about the applicability of

the data within the terms of reference of the model. There was no limitation in comparing samples to the ones

In general it could be observed that the 4 seconds sample size chosen in the experiment according to ITU-T

Recommendation P.835 [i.3] lead to a more difficult task even for expert listeners, especially in the case of non

stationary background noises. It is more difficult to identify the nature of the noise itself and then identify in addition

possible impairments introduced by the signal processing or by the network impairments. It is very likely that some

comparatively high standard deviations seen in the data are caused by these effects.

In general the French database is in line with the ToR except network condition NII. In network condition NII 1 %

packet loss was chosen which is too low for the conditions to be evaluated. Due to the inhomogeneously distributed

packet losses there are conditions where no packet loss is audible up to conditions where 5 out of 6 samples show

packet loss. Furthermore the packet loss may occur during speech as well as during the noise periods. The impact of the

different packet losses is not controlled with respect to their occurrence due to the s