Speech and multimedia Transmission Quality (STQ) - Speech Quality performance in the presence of background noise - Part 3: Background noise transmission - Objective test methods

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.
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 scope of the objective methods.
• 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 quality in the presence of background noise taking into account:
- the speech quality;
- the background noise transmission quality;
- the overall quality.
• The document is to be used in conjunction with:
- 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 communication systems.
- 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 for the data forming the basis of the present document.
- French speech sentences as defined in ITU-T Recommendation P.501 [i.13] for wideband and English speech sentences as defined in ITU-T Recommendation P.501 [i.13] for narrowband.

Kakovost prenosa govora in večpredstavnih vsebin (STQ) - Kakovost govora ob prisotnosti šuma ozadja - 3. del: Prenos šuma ozadja - Objektivne preskusne metode

Ta dokument je namenjen identifikaciji in opredelitvi preskusnih metodologij, ki se lahko uporabljajo za objektivno vrednotenje delovanja ozkopasovnih in širokopasovnih terminalov in sistemov za govorno komunikacijo v prisotnosti šuma ozadja.
Šum ozadja je težava v večini situacij in razmer in se mora upoštevati pri terminalih in v omrežjih. Ta dokument zagotavlja informacije o preskusnih metodah, ki se uporabljajo za objektivno vrednotenje kakovosti govora v prisotnosti šuma ozadja. Ta dokument vključuje:
• opis strokovnega postopka po vrednotenju za izbiro subjektivnih preskusnih podatkov, ki je v področju uporabe objektivnih metod;
• rezultate vrednotenja uspešnosti trenutno obstoječih metod, opisanih v Priporočilu ITU-T P.862 [i.16], [i.17] in TOSQA2001 [i.19], ki je izbran za vrednotenje terminalov v okviru dogodkov za preskus kakovosti govora ETSI VoIP [i.8], [i.9], [i.10] in [i.11];
• metodo, uporabljeno za objektivno določanje različnih parametrov, ki vplivajo na kakovost govora v prisotnosti šuma ozadja, ki upošteva:
- kakovost govora,
- kakovost prenosa šuma ozadja,
- celovito kakovost.
• Dokument je namenjen uporabi skupaj s/z:
- EG 202 396-1 [i.1], ki opisuje nastavitev snemanja in predvajanja za realistično simulacijo scenarijev šuma ozadja v laboratorijskih okoljih za vrednotenje delovanja terminalov in komunikacijskih sistemov;
- EG 202 396-2 [i.2], ki opisuje simulacijo okvar omrežja in način simulacije realističnih scenarijev prenosa v omrežju ter vsebuje
metodologijo in rezultate subjektivnega ocenjevanja podatkov, ki tvorijo osnovo tega dokumenta;
- francoskimi stavki, kot jih opredeljuje Priporočilo ITU-T P.501 [i.13] za široke pasove, in angleškimi stavki, kot jih opredeljuje Priporočilo ITU-T P.501 [i.13] za ozke pasove.

General Information

Status
Published
Publication Date
18-May-2011
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
12-Apr-2011
Due Date
17-Jun-2011
Completion Date
19-May-2011

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SLOVENSKI STANDARD
SIST-V ETSI/EG 202 396-3 V1.3.0:2011
01-junij-2011
.DNRYRVWSUHQRVDJRYRUDLQYHþSUHGVWDYQLKYVHELQ 674 .DNRYRVWJRYRUDRE
SULVRWQRVWLãXPDR]DGMDGHO3UHQRVãXPDR]DGMD2EMHNWLYQHSUHVNXVQH
PHWRGH

Speech and multimedia Transmission Quality (STQ) - Speech Quality performance in the

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

methods
Ta slovenski standard je istoveten z: EG 202 396-3 Version 1.3.0
ICS:
33.040.35 Telefonska omrežja Telephone networks
SIST-V ETSI/EG 202 396-3 V1.3.0:2011 en

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

---------------------- Page: 1 ----------------------
SIST-V ETSI/EG 202 396-3 V1.3.0:2011
---------------------- Page: 2 ----------------------
SIST-V ETSI/EG 202 396-3 V1.3.0:2011
ETSI EG 202 396-3 V1.3.1 (2011-02)
ETSI Guide
Speech and multimedia Transmission Quality (STQ);
Speech Quality performance
in the presence of background noise
Part 3: Background noise transmission -
Objective test methods
---------------------- Page: 3 ----------------------
SIST-V ETSI/EG 202 396-3 V1.3.0:2011
2 ETSI EG 202 396-3 V1.3.1 (2011-02)
Reference
REG/STQ-00167
Keywords
noise, QoS, quality, speech
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The copyright and the foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 2011.
All rights reserved.
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ETSI
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SIST-V ETSI/EG 202 396-3 V1.3.0:2011
3 ETSI EG 202 396-3 V1.3.1 (2011-02)
Contents

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

ETSI
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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

Annex H: Extension of the EG 202 396-3 Speech Quality Test Method to Narrowband:

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

ETSI
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SIST-V ETSI/EG 202 396-3 V1.3.0:2011
5 ETSI EG 202 396-3 V1.3.1 (2011-02)
Intellectual Property Rights

IPRs essential or potentially essential to the present document may have been declared to ETSI. The information

pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found

in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in

respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web

server (http://webapp.etsi.org/IPR/home.asp).

Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee

can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web

server) which are, or may be, or may become, essential to the present document.
Foreword

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

(STQ).

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

background noise transmission".

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 1: "Background noise simulation technique and background noise database";

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

Part 3: "Background noise transmission - Objective test methods".
ETSI
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6 ETSI EG 202 396-3 V1.3.1 (2011-02)
1 Scope

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.

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

scope of the objective methods.

• 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

quality in the presence of background noise taking into account:
- the speech quality;
- the background noise transmission quality;
- the overall quality.
• The document is to be used in conjunction with:

- 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

communication systems.

- 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

for the data forming the basis of the present document.

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

speech sentences as defined in ITU-T Recommendation P.501 [i.13] for narrowband.
2 References

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

reference document (including any amendments) applies.

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

http://docbox.etsi.org/Reference.

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

their long term validity.
2.1 Normative references

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

Not applicable.
ETSI
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7 ETSI EG 202 396-3 V1.3.1 (2011-02)
2.2 Informative references

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

user with regard to a particular subject area.

[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

and background noise database".

[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

- Network Simulation - Subjective Test Database and Results".

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

communication systems that include noise suppression algorithm".

[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

'96, Liverpool, UK.

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

transmission using the "Relative Approach"".

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

acoustics, T-Systems Nova.

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

Also available as ETSI TR 102 648-3.

[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.10] ETSI 3rd Speech Quality Test Event: "Anonymized Test Report "IP Phones"".

[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

Packet Loss Concealment Implementations", DAGA, March 2003, Aachen, Germany.
[i.13] ITU-T Recommendation P.501: "Test Signals for Use in Telephonometry".

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

Electronics and Communications (AEÜ) vol. 59, 2005, p. 157-165.
NOTE: Available at: http://www.elsevier.de/aeue.

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

Vehicles" R. Sottek, W. Krebber, G. Stanley.

[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

codecs".

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

MOS-LQO".

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

assessment of wideband telephone networks and speech codecs".
ETSI
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[i.19] ITU-T Recommendation SG 12 Contribution 19: "Results of objective speech quality assessment

of wideband speech using the Advanced TOSQA2001".
[i.20] ITU-T Recommendation G.722: "7 kHz audio-coding within 64 kbit/s".

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

Multi-Rate Wideband (AMR-WB)".

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

[i.23] ITU-T Recommendation P.57: "Artificial ears".
[i.24] M. Spiegel: "Theory and problems of statistics", McGraw Hill, 1998.

[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,

1993".

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

wideband digital codecs".

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

rapporteur's meeting (Solothurn, Germany, 6-10 March 2000)".

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

Analog and Digital Filters", 1993.
3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
ACR Absolute Comparison Rating
AMR Adaptive MultiRate
ASL Active Speech Level
NOTE: According to ITU-T Recommendation P.56 [i.22].
BGN BackGround Noise
CDF Cumulative Density Function
DB Data Base
dB SPL Sound Pressure Level re 20 µPa in dB
G-MOS Global MOS
NOTE: MOS related to the overall sample.
HP HighPass
IP Internet Protocol
IRS Intermediate Reference System
ITU International Telecommunication Union
ITU-T Telecom Standardization Body of ITU
MOS Mean Opinion Score
MOS-LQSN Mean Opinion Score - Listening Quality Subjective Noise
MRP Mouth Reference Point
NI Network I conditions
NII Network II conditions
NIII Network III conditions
NB NarrowBand
N-MOS Noise MOS
NOTE: MOS related to the noise transmission only.
ETSI
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9 ETSI EG 202 396-3 V1.3.1 (2011-02)
NR Noise Reduction
NR (filter) Noise Reduction (filter)
PESQ Perceptual Evaluation of Speech Quality
PLC Packet Loss Concealment
RCV ReCeiVe
RMSE Random Mean Square Error
S-MOS Speech MOS
NOTE: MOS related to the speech signal only.
SNR Signal to Noise Ratio
STF Specialized Task Force
TMOS TOSQA Mean Opinion Score
TOR Terms Of Reference
TOSQA Telecommunication Objective Speech Quality Assessment
VAD Voice Activity Detection
VoIP Voice over IP
WB WideBand
4 Speech signals to be used

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

with the objective model.

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

taken from ITU-T Recommendation P.501 [i.13].

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

taken from ITU-T Recommendation P.501 [i.13].
5 Selection of the data within the scope of the
wideband objective model: Experts evaluation
5.1 Selection process

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

for subjective evaluation.

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

leading to non consistent judgements within this condition.
ETSI
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4) Inconsistencies due to ITU-T Recommendation P.56 [i.22] level adjustment process chosen for the complete

files including the background noise.

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

model.

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

above.

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

was used since this was the one used in the French and Czech test setup.

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

previously heard.
5.2 Results

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.

5.3 French database

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

...

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