SIST-V ETSI/EG 202 396-1 V1.2.2:2009
(Main)Speech Processing, Transmission and Quality Aspects (STQ) - Speech quality performance in the presence of background noise - Part 1: Background noise simulation technique and background noise database
Speech Processing, Transmission and Quality Aspects (STQ) - Speech quality performance in the presence of background noise - Part 1: Background noise simulation technique and background noise database
The quality of background noise transmission is an important factor, which significantly contributes to the perceived overall quality of speech. Existing and even more the new generation of terminals, networks and system configurations including broadband services can be greatly improved with a proper design of terminals and systems in the presence of background noise. The present document:
-describes a noise simulation environment using realistic background noise scenarios for laboratory use;
-contains a database including the relevant background noise samples for subjective and objective evaluation.
The present document provides information about the recording techniques needed for background noise recordings and discusses the advantages and drawbacks of existing methods. The present document describes the requirements for laboratory conditions. The loudspeaker setup and the loudspeaker calibration and equalization procedure are described. The simulation environment specified can be used for the evaluation and optimization of terminals and of complex configurations including terminals, networks and other configurations. The main application areas should be: office, home and car environment. The setup and database as described in the present document are applicable for:
- Objective performance evaluation of terminals in different (simulated) background noise environments.
- Speech processing evaluation by using the pre-processed speech signal in the presence of background noise, recorded by a terminal.
- Subjective evaluation of terminals by performing conversational tests, specific double talk tests or talking and listening tests in the presence of background noise.
- Subjective evaluation in third party listening tests by recording the speech samples of terminals in the presence of background noise.
Vidiki obdelave, prenosa in kakovosti govora (STQ) - Zmogljivost kakovosti govora v prisotnosti šuma ozadja - 1. del: Simulacijska tehnika šuma ozadja in podatkovna zbirka šumov ozadja
General Information
Buy Standard
Standards Content (Sample)
ETSI EG 202 396-1 V1.2.2 (2008-09)
ETSI Guide
Speech Processing, Transmission and Quality Aspects (STQ);
Speech quality performance
in the presence of background noise;
Part 1: Background noise simulation technique
and background noise database
---------------------- Page: 1 ----------------------
2 ETSI EG 202 396-1 V1.2.2 (2008-09)
Reference
REG/STQ-00131
Keywords
performance, quality, speech
ETSI
650 Route des Lucioles
F-06921 Sophia Antipolis Cedex - FRANCE
Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16
Siret N° 348 623 562 00017 - NAF 742 C
Association à but non lucratif enregistrée à la
Sous-Préfecture de Grasse (06) N° 7803/88
Important notice
Individual copies of the present document can be downloaded from:
http://www.etsi.org
The present document may be made available in more than one electronic version or in print. In any case of existing or
perceived difference in contents between such versions, the reference version is the Portable Document Format (PDF).
In case of dispute, the reference shall be the printing on ETSI printers of the PDF version kept on a specific network drive
within ETSI Secretariat.
Users of the present document should be aware that the document may be subject to revision or change of status.
Information on the current status of this and other ETSI documents is available at
http://portal.etsi.org/tb/status/status.asp
If you find errors in the present document, please send your comment to one of the following services:
http://portal.etsi.org/chaircor/ETSI_support.asp
Copyright Notification
No part may be reproduced except as authorized by written permission.
The copyright and the foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 2008.
All rights reserved.
TM TM TM TM
DECT , PLUGTESTS , UMTS , TIPHON , the TIPHON logo and the ETSI logo are Trade Marks of ETSI registered
for the benefit of its Members.
TM
3GPP is a Trade Mark of ETSI registered for the benefit of its Members and of the 3GPP Organizational Partners.
ETSI
---------------------- Page: 2 ----------------------
3 ETSI EG 202 396-1 V1.2.2 (2008-09)
Contents
Intellectual Property Rights.5
Foreword.5
Introduction .5
1 Scope.6
2 References.6
2.1 Normative references.7
2.2 Informative references.7
3 Definitions and abbreviations.8
3.1 Definitions.8
3.2 Abbreviations.8
4 Overview of existing methods for realistic sound reproduction.8
4.1 Introduction.8
4.2 Surround Sound Techniques.9
4.3 IOSONO.10
4.4 Eidophonie .10
4.5 Four-loudspeaker arrangement for playback of binaurally recorded signals.11
4.6 NTT Background-Noise Database.12
4.7 General conclusions.12
5 Recording arrangement .13
5.1 Binaural equalization.13
5.2 The equalization procedure .13
6 Loudspeaker Setup for Background Noise Simulation .15
6.1 Test Room Requirements .15
6.2 Loudspeaker Positioning.15
6.3 Equalization and Calibration .16
6.4 Accuracy of the reproduction arrangement .21
6.4.1 Comparison between original sound field and simulated sound field.21
6.4.2 Displacement of the test arrangement in the simulated sound field.22
6.4.3 Transmission of background noise: Comparison of terminal performance in the original sound field
and the simulated sound field .24
7 Background Noise Simulation in cars .28
7.1 General setup.28
7.2 Recording arrangement.29
7.2.1 Recording setup with the terminal's microphone.29
7.2.2 Recording setup with a pair of cardioid microphones.30
7.3 Equalization and Calibration with the terminal's microphone.30
7.4 Equalization and Calibration with a pair of cardioid microphones .35
7.5 Accuracy of the reproduction arrangement .40
7.5.1 Comparison between original sound field and simulated sound field.40
7.5.2 Transmission of background noise: Comparison of terminal performance in the original sound field
and the simulated sound field .41
8 Background Noise Database .43
8.1 Binaural signals.44
8.2 Stereophonic signals.46
Annex A: Comparison of Tests in Sending Direction and D-Values Conducted in Different
Rooms.47
A.1 Test Setup.47
A.2 Results of the Tests .48
A.2.1 Sending Frequency Response Characteristics and SLR .48
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4 ETSI EG 202 396-1 V1.2.2 (2008-09)
A.2.2 D-Value with Pink Noise .48
A.2.3 D-Value with Cafeteria Noise .49
A.3 Conclusions.49
Annex B: Graphs.50
History .58
ETSI
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5 ETSI EG 202 396-1 V1.2.2 (2008-09)
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 Processing, Transmission and Quality
Aspects (STQ).
The present document is part 1 of a multi-part deliverable covering Speech Processing, Transmission and Quality
Aspects (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".
Introduction
Background noise is present in most of the conversations today. Background noise may impact the speech
communication performance to terminal and network equipment significantly. Therefore testing and optimization of
such equipment is necessary using realistic background noises. Furthermore reproducible conditions for the tests are
required which can be guaranteed only under lab type condition.
The present document addresses this issue by describing a methodology for recording and playback of background
noises under well defined and calibratable conditions in a lab-type environment. Furthermore a database with real
background noises is included.
ETSI
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6 ETSI EG 202 396-1 V1.2.2 (2008-09)
1 Scope
The quality of background noise transmission is an important factor, which significantly contributes to the perceived
overall quality of speech. Existing and even more the new generation of terminals, networks and system configurations
including broadband services can be greatly improved with a proper design of terminals and systems in the presence of
background noise. The present document:
• describes a noise simulation environment using realistic background noise scenarios for laboratory use;
• contains a database including the relevant background noise samples for subjective and objective evaluation.
The present document provides information about the recording techniques needed for background noise recordings and
discusses the advantages and drawbacks of existing methods. The present document describes the requirements for
laboratory conditions. The loudspeaker setup and the loudspeaker calibration and equalization procedure are described.
The simulation environment specified can be used for the evaluation and optimization of terminals and of complex
configurations including terminals, networks and other configurations. The main application areas should be: office,
home and car environment.
The setup and database as described in the present document are applicable for:
• Objective performance evaluation of terminals in different (simulated) background noise environments.
• Speech processing evaluation by using the pre-processed speech signal in the presence of background noise,
recorded by a terminal.
• Subjective evaluation of terminals by performing conversational tests, specific double talk tests or talking and
listening tests in the presence of background noise.
• Subjective evaluation in third party listening tests by recording the speech samples of terminals in the presence
of background noise.
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific.
• For a specific reference, subsequent revisions do not apply.
• Non-specific reference may be made only to a complete document or a part thereof and only in the following
cases:
- if it is accepted that it will be possible to use all future changes of the referenced document for the
purposes of the referring document;
- for informative references.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
For online referenced documents, information sufficient to identify and locate the source shall be provided. Preferably,
the primary source of the referenced document should be cited, in order to ensure traceability. Furthermore, the
reference should, as far as possible, remain valid for the expected life of the document. The reference shall include the
method of access to the referenced document and the full network address, with the same punctuation and use of upper
case and lower case letters.
NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee
their long term validity.
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7 ETSI EG 202 396-1 V1.2.2 (2008-09)
2.1 Normative references
The following referenced documents are indispensable for the application of the present document. For dated
references, only the edition cited applies. For non-specific references, the latest edition of the referenced document
(including any amendments) applies.
Not applicable.
2.2 Informative references
The following referenced documents are not essential to the use of the present document but they assist the user with
regard to a particular subject area. For non-specific references, the latest version of the referenced document (including
any amendments) applies.
[i.1] Surround Sound Past, Present, and Future: "A history of multichannel audio from mag stripe to
Dolby Digital", Joseph Hull - Dolby Laboratories Inc.
NOTE: See at http://www.dolby.com/assets/pdf/tech_library/2_Surround_Past.Present.pdf.
[i.2] AES preprint 3332 (1992): "Improved Possibilities of Binaural Recording and Playback
Techniques", K. Genuit, H.W. Gierlich; U. Künzli.
NOTE: See at http://www.aes.org/e-lib/browse.cfm?elib=6801.
[i.3] AES preprint 3732 (1993): "A System for the Reproduction Technique for Playback of Binaural
Recordings", N. Xiang, K. Genuit, H.W. Gierlich.
NOTE: See at http://www.aes.org/e-lib/browse.cfm?elib=6501.
[i.4] NTTAT Database: "Ambient Noise Database CD-ROM".
NOTE: See at http://www.ntt-at.com/products_e/noise-DB/index.html.
[i.5] ISO 11904-1: "Acoustics - Determination of sound immission from sound sources placed close to
the ear - Part 1: Technique using a microphone in a real ear (MIRE technique)".
[i.6] Spatial Hearing: "The psychophysics of human sound localization", J. Blauert.
[i.7] ITU-T Recommendation P.57: "Artificial ears".
[i.8] ITU-T Recommendation P.58: "Head and torso simulator for telephonometry".
[i.9] ITU-T Recommendation P.340: "Transmission characteristics and speech quality parameters of
hands-free terminals".
[i.10] ITU-T recommendation P.64: "Determination of sensitivity/frequency characteristics of local
telephone systems".
[i.11] ITU-T Recommendation G.722: "7 kHz audio-coding within 64 kbit/s".
[i.12] Genuit, K.: "A Description of the Human Outer Ear Transfer Function by Elements of
Communication Theory (No. B6-8)". Proceedings of the 12th International Congress on Acoustics.
Toronto published on behalf of the Technical Program Committee by the Executive Committee of
the 12th International Congress on Acoustics.
[i.13] IEC 60050-722: "International Electrotechnical Vocabulary - Chapter 722: Telephony".
[i.14] "Wellenfeldsynthese - Eine neue Dimension der 3D-Audiowiedergabe"; Fernseh- und Kino-
Technik, Nr. 11/2002, pp. 735-738.
[i.15] http://www.iosono-sound.de.
[i.16] "Ein neues Verfahren der raumbezogenen Stereophonie mit verbesserter Übertragung der
Rauminformation"; P. Scherer, Rundfunktechnische Mitteilungen, 1977, pp. 196-204.
ETSI
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8 ETSI EG 202 396-1 V1.2.2 (2008-09)
[i.17] ETSI EG 202 396-1 (V.1.1.2): "Speech quality performance in the presence of background noise;
Part 1: Background noise simulation technique and background noise database".
[i.18] ETSI TS 151 010-1: "Digital cellular telecommunications system (Phase 2+); Mobile Station (MS)
conformance specification; Part 1: Conformance specification (3GPP TS 51.010-1)".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
crosstalk: appearance of undesired energy in a channel, owing to the presence of a signal in another channel, caused
by, for example induction, conduction or non linearity
NOTE: See IEC 60050-722 [i.13].
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
CD Compact Disc
FFT Fast Fourier Transform
FIR Finite Impulse Response
HATS Head And Torso Simulator
IIR Infinite Impulse Response
MIRE Microphone In Real Ear
NTT Nippon Telegraph and Telephone Corporation
SLR Send Loudness Rating
VHF Very High Frequency
4 Overview of existing methods for realistic sound
reproduction
4.1 Introduction
In general the existing methods for close to original sound recording and reproduction aimed for different applications:
• Techniques intending to reproduce the actual sound field.
• Techniques providing hearing adequate (ear related) signals in the human ear canal.
• Techniques generating artificial acoustical environments.
Within this clause the different methods are briefly described and their applicability for close to original sound-filed
reproduction is discussed. A variety of methods have been studied, in the following a summary of the most important
ones relevant to the present document is given. The different methods were analyzed on the basis of the following
requirements:
• The background noise recording technique should be:
- easy to use;
- easy to calibrate;
- capable of wideband recording;
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9 ETSI EG 202 396-1 V1.2.2 (2008-09)
- available at reasonable costs;
- mostly compatible to existing standards and procedures used in telecommunications testing;
- applicable to different environments (at least office, home and car).
• The background noise simulation arrangement should:
- be easy to setup;
- not require any specific acoustical treatment for the simulation requirement;
- provide a mostly realistic background noise simulation for all typical background noises faced with in
telecommunication applications;
- be easy to calibrate;
- be mostly insensitive against the positioning of (test)-objects in the simulated sound field;
- be applicable to all typical terminals used in telecommunication;
- be available at reasonable costs.
4.2 Surround Sound Techniques
The basics of surround techniques are found in cinema applications. The virtual image provided by stereophonic
presentation of sounds seemed not to be sufficient for the large screen display in cinema. In the 1950s 4-channel and
6-channel soundtracks recorded on magnetic stripes associated to the films were developed, 4-channel and 6-channel
loudspeaker systems were installed in cinemas to reproduce the multichannel sounds. The newer techniques were
mostly developed and marketed by Dolby® [i.1]: Dolby Surround, Dolby Surround Pro Logic, Dolby Digital and Dolby
Digital Surround are examples for the techniques introduced more recently. The most common configuration is the
"5.1-configuration" used in cinema but in home applications as well. The reproduction system consists of left and right
channel, a centre speaker, two surround channels (left and right, arranged in the back of the listener) and a low
frequency channel for low frequency effects.
The aim of all surround system is to create an artificial acoustical image in the recording studio rather than recording a
real acoustical scenario and providing true to original playback possibilities.
On the recording side special surround encoders are used allowing the 5-channel signal to be encoded from a special
mixing console to the 5.1 digital data stream. The playback system consists of a special decoder allowing to separate the
5 channels again and distribute them on the 5.1 loudspeaker playback system. The systems are mono and stereo
compatible and can handle the older 4 channel surround techniques by a specific decoder.
Applications:
Typical applications for surround systems are cinemas and home theatres. The source material is produced by
professional recording studios using multi-channel mixing consoles and specific 5.1 decoding techniques. In mostly all
cases virtual environments are created which support the visual image by an appropriate acoustical image.
Conclusion:
Surround techniques are designed for creating acoustical images rather than for close to original recording and
reproduction. Although the spatial impression provided by surround techniques is sometimes remarkable the acoustical
image created is always artificial. Due to the lack of easy to use recording techniques allowing a spatial recording of a
sound field surround sound techniques are not suitable for creation of a background noise database with realistic
background noises and calibrated background noise simulation in a lab.
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10 ETSI EG 202 396-1 V1.2.2 (2008-09)
4.3 IOSONO
The IOSONO® sound system (see [i.14] and [i.15]) is based on the Wave-Field Synthesis. It employs Huygens
principle of wave theory. Applied to acoustics this principle means that it is possible to reproduce any form of wave
front with an array of loudspeakers, so that virtual sound sources can be placed anywhere within a listening area. For
practical use it is necessary to position loudspeakers all-round the playback room. In order to generate realistic sound
fields the input signal for each loudspeaker has to be calculated separately. For this purpose each single sound source
(e.g. voices) has to be recorded individually. If the recordings are done in a room, the characteristics (like reverberation)
of the recording room also have to be recorded separately. All resulting sound tracks are then mixed and manipulated
during the post-editing process and the reproduction.
The natural and realistic spatial sound reproduction is then achieved in a wide area of the play back room. Common 5.1
stereo systems achieve a "realistic" sound reproduction only in a small area of the reproduction room.
Applications:
Typical applications are sound systems for home use, cinemas and other entertainment events. The IOSONO sound
system is also able to play back recordings made in common stereo or 5.1 stereo techniques.
Conclusion:
The drawbacks of this method are the components needed: a sophisticated recording system, a powerful computing unit
for real-time mixing the large number of recorded sound tracks and the number of loudspeakers that have to be installed
in the listening room. In a common size cinema for example about 200 loudspeakers are needed.
The advantage is that with the IOSONO sound system a very realistic sound reproduction is possible, but it requires an
enormous effort, which is too high for daily use in laboratories.
4.4 Eidophonie
This method (see [i.16]) was developed for realistic sound reproduction using the VHF transmission technique. The
main principle is to separate the base signal from the part of the signal, which contains the information about the
direction of sound incidence.
st
For recording a 1 order gradient microphone with a cardioid directivity is used. During the recordings its directivity
rotates with 38 kHz in the recording plane. This "turning microphone" provides an amplitude-modulated signal at its
electrical output. The resulting side bands are out of the transmitted frequency range. But these side bands contain the
information of the direction of sound incidence. Using the VHF- transmission techniques this phase information can be
nd
transmitted within the 2 audio-frequency channel.
The sound reproduction is made by a spatial demodulation: a switch is positioned before each loudspeaker and each
switches synchronously with the turning directivity. So a low pass filtered short-term section of the signal containing
the information of the direction of sound incidence is played back on each loudspeaker. The loudspeakers are positioned
all around the playback room.
Applications:
Eidophonie was developed to provide a realistic sound environment using a signal received from a VHF broadcast
station. With this technique the common stereo sound reproduction should be improved. Nevertheless Eidophonie is
also compatible to common mono and stereo recordings.
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11 ETSI EG 202 396-1 V1.2.2 (2008-09)
Conclusion:
Benefits of this system are that three loudspeakers are sufficient to produce a realistic sound field. Using more
loudspeakers (e.g. 16) the spatial sound reproduction gets more and more independent from the listening position.
Moreover the independency of the transmitted sound from the acoustics of the reproduction room increases with the
number of loudspeakers used. But there are significant limitations of the method: The microphone directivity is
frequency dependent and not ideal. Therefore the interference between the different channels is created. A second
problem is the loudspeaker directivity, which does not fit the microphone directivity. This problem could be reduced if
the number of channels would be increased. This however is not possible due to the limited directivity of the
microphone arrangement used.
Localization of sound sources is hardly possible due to the interference effects of the microphone signals and the
loudspeakers. At close to original reproduction depends on the number and distribution of sound sources present. For
most of the sound source combinations this goal cannot be achieved.
In general the coding technique needed to record the sound field by a "turning microphone", is complicated and not
available commercially. A further drawback of this method is the complicated decoding technique needed on the
reproduction side, which is also not commercially available.
4.5 Four-loudspeaker arrangement for playback of binaurally
recorded signals
This reproduction procedure was originally investigated to reproduce binaurally signals recorded using artificial head
technology. It improves the impressions of direction and distance. Four loudspeakers are typically positioned in a
square formation around a central point (listening point) equidistantly e.g. 2 m. The binaural recordings are played back
as follows: the two left-hand loudspeakers receive the same free-field equalized artificial head signal of the left-han
...
Final draft ETSI EG 202 396-1 V1.2.2 (2008-06)
ETSI Guide
Speech Processing, Transmission and Quality Aspects (STQ);
Speech quality performance
in the presence of background noise;
Part 1: Background noise simulation technique
and background noise database
---------------------- Page: 1 ----------------------
2 Final draft ETSI EG 202 396-1 V1.2.2 (2008-06)
Reference
REG/STQ-00131
Keywords
performance, quality, speech
ETSI
650 Route des Lucioles
F-06921 Sophia Antipolis Cedex - FRANCE
Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16
Siret N° 348 623 562 00017 - NAF 742 C
Association à but non lucratif enregistrée à la
Sous-Préfecture de Grasse (06) N° 7803/88
Important notice
Individual copies of the present document can be downloaded from:
http://www.etsi.org
The present document may be made available in more than one electronic version or in print. In any case of existing or
perceived difference in contents between such versions, the reference version is the Portable Document Format (PDF).
In case of dispute, the reference shall be the printing on ETSI printers of the PDF version kept on a specific network drive
within ETSI Secretariat.
Users of the present document should be aware that the document may be subject to revision or change of status.
Information on the current status of this and other ETSI documents is available at
http://portal.etsi.org/tb/status/status.asp
If you find errors in the present document, please send your comment to one of the following services:
http://portal.etsi.org/chaircor/ETSI_support.asp
Copyright Notification
No part may be reproduced except as authorized by written permission.
The copyright and the foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 2008.
All rights reserved.
TM TM TM TM
DECT , PLUGTESTS , UMTS , TIPHON , the TIPHON logo and the ETSI logo are Trade Marks of ETSI registered
for the benefit of its Members.
TM
3GPP is a Trade Mark of ETSI registered for the benefit of its Members and of the 3GPP Organizational Partners.
ETSI
---------------------- Page: 2 ----------------------
3 Final draft ETSI EG 202 396-1 V1.2.2 (2008-06)
Contents
Intellectual Property Rights.5
Foreword.5
Introduction .5
1 Scope.6
2 References.6
2.1 Normative references.7
2.2 Informative references.7
3 Definitions and abbreviations.8
3.1 Definitions.8
3.2 Abbreviations.8
4 Overview of existing methods for realistic sound reproduction.8
4.1 Introduction.8
4.2 Surround Sound Techniques.9
4.3 IOSONO.10
4.4 Eidophonie .10
4.5 Four-loudspeaker arrangement for playback of binaurally recorded signals.11
4.6 NTT Background-Noise Database.12
4.7 General conclusions.12
5 Recording arrangement .13
5.1 Binaural equalization.13
5.2 The equalization procedure .13
6 Loudspeaker Setup for Background Noise Simulation .15
6.1 Test Room Requirements .15
6.2 Loudspeaker Positioning.15
6.3 Equalization and Calibration .16
6.4 Accuracy of the reproduction arrangement .21
6.4.1 Comparison between original sound field and simulated sound field.21
6.4.2 Displacement of the test arrangement in the simulated sound field.22
6.4.3 Transmission of background noise: Comparison of terminal performance in the original sound field
and the simulated sound field .24
7 Background Noise Simulation in cars .28
7.1 General setup.28
7.2 Recording arrangement.29
7.2.1 Recording setup with the terminal's microphone.29
7.2.2 Recording setup with a pair of cardioid microphones.30
7.3 Equalization and Calibration with the terminal's microphone.30
7.4 Equalization and Calibration with a pair of cardioid microphones .35
7.5 Accuracy of the reproduction arrangement .40
7.5.1 Comparison between original sound field and simulated sound field.40
7.5.2 Transmission of background noise: Comparison of terminal performance in the original sound field
and the simulated sound field .41
8 Background Noise Database .43
8.1 Binaural signals.44
8.2 Stereophonic signals.46
Annex A: Comparison of Tests in Sending Direction and D-Values Conducted in Different
Rooms.47
A.1 Test Setup.47
A.2 Results of the Tests .48
A.2.1 Sending Frequency Response Characteristics and SLR .48
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4 Final draft ETSI EG 202 396-1 V1.2.2 (2008-06)
A.2.2 D-Value with Pink Noise .48
A.2.3 D-Value with Cafeteria Noise .49
A.3 Conclusions.49
Annex B: Graphs.50
History .58
ETSI
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5 Final draft ETSI EG 202 396-1 V1.2.2 (2008-06)
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 Processing, Transmission and Quality
Aspects (STQ), and is now submitted for the ETSI standards Membership Approval Procedure.
The present document is part 1 of a multi-part deliverable covering Speech Processing, Transmission and Quality
Aspects (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".
Introduction
Background noise is present in most of the conversations today. Background noise may impact the speech
communication performance to terminal and network equipment significantly. Therefore testing and optimization of
such equipment is necessary using realistic background noises. Furthermore reproducible conditions for the tests are
required which can be guaranteed only under lab type condition.
The present document addresses this issue by describing a methodology for recording and playback of background
noises under well defined and calibratable conditions in a lab-type environment. Furthermore a database with real
background noises is included.
ETSI
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6 Final draft ETSI EG 202 396-1 V1.2.2 (2008-06)
1 Scope
The quality of background noise transmission is an important factor, which significantly contributes to the perceived
overall quality of speech. Existing and even more the new generation of terminals, networks and system configurations
including broadband services can be greatly improved with a proper design of terminals and systems in the presence of
background noise. The present document:
• describes a noise simulation environment using realistic background noise scenarios for laboratory use;
• contains a database including the relevant background noise samples for subjective and objective evaluation.
The present document provides information about the recording techniques needed for background noise recordings and
discusses the advantages and drawbacks of existing methods. The present document describes the requirements for
laboratory conditions. The loudspeaker setup and the loudspeaker calibration and equalization procedure are described.
The simulation environment specified can be used for the evaluation and optimization of terminals and of complex
configurations including terminals, networks and other configurations. The main application areas should be: office,
home and car environment.
The setup and database as described in the present document are applicable for:
• Objective performance evaluation of terminals in different (simulated) background noise environments.
• Speech processing evaluation by using the pre-processed speech signal in the presence of background noise,
recorded by a terminal.
• Subjective evaluation of terminals by performing conversational tests, specific double talk tests or talking and
listening tests in the presence of background noise.
• Subjective evaluation in third party listening tests by recording the speech samples of terminals in the presence
of background noise.
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific.
• For a specific reference, subsequent revisions do not apply.
• Non-specific reference may be made only to a complete document or a part thereof and only in the following
cases:
- if it is accepted that it will be possible to use all future changes of the referenced document for the
purposes of the referring document;
- for informative references.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
For online referenced documents, information sufficient to identify and locate the source shall be provided. Preferably,
the primary source of the referenced document should be cited, in order to ensure traceability. Furthermore, the
reference should, as far as possible, remain valid for the expected life of the document. The reference shall include the
method of access to the referenced document and the full network address, with the same punctuation and use of upper
case and lower case letters.
NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee
their long term validity.
ETSI
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7 Final draft ETSI EG 202 396-1 V1.2.2 (2008-06)
2.1 Normative references
The following referenced documents are indispensable for the application of the present document. For dated
references, only the edition cited applies. For non-specific references, the latest edition of the referenced document
(including any amendments) applies.
Not applicable.
2.2 Informative references
The following referenced documents are not essential to the use of the present document but they assist the user with
regard to a particular subject area. For non-specific references, the latest version of the referenced document (including
any amendments) applies.
[i.1] Surround Sound Past, Present, and Future: "A history of multichannel audio from mag stripe to
Dolby Digital", Joseph Hull - Dolby Laboratories Inc.
NOTE: See at http://www.dolby.com/assets/pdf/tech_library/2_Surround_Past.Present.pdf.
[i.2] AES preprint 3332 (1992): "Improved Possibilities of Binaural Recording and Playback
Techniques", K. Genuit, H.W. Gierlich; U. Künzli.
NOTE: See at http://www.aes.org/e-lib/browse.cfm?elib=6801.
[i.3] AES preprint 3732 (1993): "A System for the Reproduction Technique for Playback of Binaural
Recordings", N. Xiang, K. Genuit, H.W. Gierlich.
NOTE: See at http://www.aes.org/e-lib/browse.cfm?elib=6501.
[i.4] NTTAT Database: "Ambient Noise Database CD-ROM".
NOTE: See at http://www.ntt-at.com/products_e/noise-DB/index.html.
[i.5] ISO 11904-1: "Acoustics - Determination of sound immission from sound sources placed close to
the ear - Part 1: Technique using a microphone in a real ear (MIRE technique)".
[i.6] Spatial Hearing: "The psychophysics of human sound localization", J. Blauert.
[i.7] ITU-T Recommendation P.57: "Artificial ears".
[i.8] ITU-T Recommendation P.58: "Head and torso simulator for telephonometry".
[i.9] ITU-T Recommendation P.340: "Transmission characteristics and speech quality parameters of
hands-free terminals".
[i.10] ITU-T recommendation P.64: "Determination of sensitivity/frequency characteristics of local
telephone systems".
[i.11] ITU-T Recommendation G.722: "7 kHz audio-coding within 64 kbit/s".
[i.12] Genuit, K.: "A Description of the Human Outer Ear Transfer Function by Elements of
Communication Theory (No. B6-8)". Proceedings of the 12th International Congress on Acoustics.
Toronto published on behalf of the Technical Program Committee by the Executive Committee of
the 12th International Congress on Acoustics.
[i.13] IEC 60050-722: "International Electrotechnical Vocabulary - Chapter 722: Telephony".
[i.14] "Wellenfeldsynthese - Eine neue Dimension der 3D-Audiowiedergabe"; Fernseh- und Kino-
Technik, Nr. 11/2002, pp. 735-738.
[i.15] http://www.iosono-sound.de.
[i.16] "Ein neues Verfahren der raumbezogenen Stereophonie mit verbesserter Übertragung der
Rauminformation"; P. Scherer, Rundfunktechnische Mitteilungen, 1977, pp. 196-204.
ETSI
---------------------- Page: 7 ----------------------
8 Final draft ETSI EG 202 396-1 V1.2.2 (2008-06)
[i.17] ETSI EG 202 396-1 (V.1.1.2): "Speech quality performance in the presence of background noise;
Part 1: Background noise simulation technique and background noise database".
[i.18] ETSI TS 151 010-1: "Digital cellular telecommunications system (Phase 2+); Mobile Station (MS)
conformance specification; Part 1: Conformance specification (3GPP TS 51.010-1)".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
crosstalk: appearance of undesired energy in a channel, owing to the presence of a signal in another channel, caused
by, for example induction, conduction or non linearity
NOTE: See IEC 60050-722 [i.13].
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
CD Compact Disc
FFT Fast Fourier Transform
FIR Finite Impulse Response
HATS Head And Torso Simulator
IIR Infinite Impulse Response
MIRE Microphone In Real Ear
NTT Nippon Telegraph and Telephone Corporation
SLR Send Loudness Rating
VHF Very High Frequency
4 Overview of existing methods for realistic sound
reproduction
4.1 Introduction
In general the existing methods for close to original sound recording and reproduction aimed for different applications:
• Techniques intending to reproduce the actual sound field.
• Techniques providing hearing adequate (ear related) signals in the human ear canal.
• Techniques generating artificial acoustical environments.
Within this clause the different methods are briefly described and their applicability for close to original sound-filed
reproduction is discussed. A variety of methods have been studied, in the following a summary of the most important
ones relevant to the present document is given. The different methods were analyzed on the basis of the following
requirements:
• The background noise recording technique should be:
- easy to use;
- easy to calibrate;
- capable of wideband recording;
ETSI
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9 Final draft ETSI EG 202 396-1 V1.2.2 (2008-06)
- available at reasonable costs;
- mostly compatible to existing standards and procedures used in telecommunications testing;
- applicable to different environments (at least office, home and car).
• The background noise simulation arrangement should:
- be easy to setup;
- not require any specific acoustical treatment for the simulation requirement;
- provide a mostly realistic background noise simulation for all typical background noises faced with in
telecommunication applications;
- be easy to calibrate;
- be mostly insensitive against the positioning of (test)-objects in the simulated sound field;
- be applicable to all typical terminals used in telecommunication;
- be available at reasonable costs.
4.2 Surround Sound Techniques
The basics of surround techniques are found in cinema applications. The virtual image provided by stereophonic
presentation of sounds seemed not to be sufficient for the large screen display in cinema. In the 1950s 4-channel and
6-channel soundtracks recorded on magnetic stripes associated to the films were developed, 4-channel and 6-channel
loudspeaker systems were installed in cinemas to reproduce the multichannel sounds. The newer techniques were
mostly developed and marketed by Dolby® [i.1]: Dolby Surround, Dolby Surround Pro Logic, Dolby Digital and Dolby
Digital Surround are examples for the techniques introduced more recently. The most common configuration is the
"5.1-configuration" used in cinema but in home applications as well. The reproduction system consists of left and right
channel, a centre speaker, two surround channels (left and right, arranged in the back of the listener) and a low
frequency channel for low frequency effects.
The aim of all surround system is to create an artificial acoustical image in the recording studio rather than recording a
real acoustical scenario and providing true to original playback possibilities.
On the recording side special surround encoders are used allowing the 5-channel signal to be encoded from a special
mixing console to the 5.1 digital data stream. The playback system consists of a special decoder allowing to separate the
5 channels again and distribute them on the 5.1 loudspeaker playback system. The systems are mono and stereo
compatible and can handle the older 4 channel surround techniques by a specific decoder.
Applications:
Typical applications for surround systems are cinemas and home theatres. The source material is produced by
professional recording studios using multi-channel mixing consoles and specific 5.1 decoding techniques. In mostly all
cases virtual environments are created which support the visual image by an appropriate acoustical image.
Conclusion:
Surround techniques are designed for creating acoustical images rather than for close to original recording and
reproduction. Although the spatial impression provided by surround techniques is sometimes remarkable the acoustical
image created is always artificial. Due to the lack of easy to use recording techniques allowing a spatial recording of a
sound field surround sound techniques are not suitable for creation of a background noise database with realistic
background noises and calibrated background noise simulation in a lab.
ETSI
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10 Final draft ETSI EG 202 396-1 V1.2.2 (2008-06)
4.3 IOSONO
The IOSONO® sound system (see [i.14] and [i.15]) is based on the Wave-Field Synthesis. It employs Huygens
principle of wave theory. Applied to acoustics this principle means that it is possible to reproduce any form of wave
front with an array of loudspeakers, so that virtual sound sources can be placed anywhere within a listening area. For
practical use it is necessary to position loudspeakers all-round the playback room. In order to generate realistic sound
fields the input signal for each loudspeaker has to be calculated separately. For this purpose each single sound source
(e.g. voices) has to be recorded individually. If the recordings are done in a room, the characteristics (like reverberation)
of the recording room also have to be recorded separately. All resulting sound tracks are then mixed and manipulated
during the post-editing process and the reproduction.
The natural and realistic spatial sound reproduction is then achieved in a wide area of the play back room. Common 5.1
stereo systems achieve a "realistic" sound reproduction only in a small area of the reproduction room.
Applications:
Typical applications are sound systems for home use, cinemas and other entertainment events. The IOSONO sound
system is also able to play back recordings made in common stereo or 5.1 stereo techniques.
Conclusion:
The drawbacks of this method are the components needed: a sophisticated recording system, a powerful computing unit
for real-time mixing the large number of recorded sound tracks and the number of loudspeakers that have to be installed
in the listening room. In a common size cinema for example about 200 loudspeakers are needed.
The advantage is that with the IOSONO sound system a very realistic sound reproduction is possible, but it requires an
enormous effort, which is too high for daily use in laboratories.
4.4 Eidophonie
This method (see [i.16]) was developed for realistic sound reproduction using the VHF transmission technique. The
main principle is to separate the base signal from the part of the signal, which contains the information about the
direction of sound incidence.
st
For recording a 1 order gradient microphone with a cardioid directivity is used. During the recordings its directivity
rotates with 38 kHz in the recording plane. This "turning microphone" provides an amplitude-modulated signal at its
electrical output. The resulting side bands are out of the transmitted frequency range. But these side bands contain the
information of the direction of sound incidence. Using the VHF- transmission techniques this phase information can be
nd
transmitted within the 2 audio-frequency channel.
The sound reproduction is made by a spatial demodulation: a switch is positioned before each loudspeaker and each
switches synchronously with the turning directivity. So a low pass filtered short-term section of the signal containing
the information of the direction of sound incidence is played back on each loudspeaker. The loudspeakers are positioned
all around the playback room.
Applications:
Eidophonie was developed to provide a realistic sound environment using a signal received from a VHF broadcast
station. With this technique the common stereo sound reproduction should be improved. Nevertheless Eidophonie is
also compatible to common mono and stereo recordings.
ETSI
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11 Final draft ETSI EG 202 396-1 V1.2.2 (2008-06)
Conclusion:
Benefits of this system are that three loudspeakers are sufficient to produce a realistic sound field. Using more
loudspeakers (e.g. 16) the spatial sound reproduction gets more and more independent from the listening position.
Moreover the independency of the transmitted sound from the acoustics of the reproduction room increases with the
number of loudspeakers used. But there are significant limitations of the method: The microphone directivity is
frequency dependent and not ideal. Therefore the interference between the different channels is created. A second
problem is the loudspeaker directivity, which does not fit the microphone directivity. This problem could be reduced if
the number of channels would be increased. This however is not possible due to the limited directivity of the
microphone arrangement used.
Localization of sound sources is hardly possible due to the interference effects of the microphone signals and the
loudspeakers. At close to original reproduction depends on the number and distribution of sound sources present. For
most of the sound source combinations this goal cannot be achieved.
In general the coding technique needed to record the sound field by a "turning microphone", is complicated and not
available commercially. A further drawback of this method is the complicated decoding technique needed on the
reproduction side, which is also not commercially available.
4.5 Four-loudspeaker arrangement for playback of binaurally
recorded signals
This reproduction procedure was originally investigated to reproduce binaurally signals recorded using artificial head
technology. It improves the impressions of direction and distance. Four loudspeakers are typically positioned in a
square formation around a central
...
SLOVENSKI STANDARD
SIST-V ETSI/EG 202 396-1 V1.2.2:2009
01-april-2009
Vidiki obdelave, prenosa in kakovosti govora (STQ) - Zmogljivost kakovosti govora
v prisotnosti šuma ozadja - 1. del: Simulacijska tehnika šuma ozadja in
podatkovna zbirka šumov ozadja
Speech Processing, Transmission and Quality Aspects (STQ) - Speech quality
performance in the presence of background noise - Part 1: Background noise simulation
technique and background noise database
Ta slovenski standard je istoveten z: EG 202 396-1 Version 1.2.2
ICS:
33.040.35 Telefonska omrežja Telephone networks
SIST-V ETSI/EG 202 396-1 V1.2.2:2009 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST-V ETSI/EG 202 396-1 V1.2.2:2009
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SIST-V ETSI/EG 202 396-1 V1.2.2:2009
ETSI EG 202 396-1 V1.2.2 (2008-09)
ETSI Guide
Speech Processing, Transmission and Quality Aspects (STQ);
Speech quality performance
in the presence of background noise;
Part 1: Background noise simulation technique
and background noise database
---------------------- Page: 3 ----------------------
SIST-V ETSI/EG 202 396-1 V1.2.2:2009
2 ETSI EG 202 396-1 V1.2.2 (2008-09)
Reference
REG/STQ-00131
Keywords
performance, quality, speech
ETSI
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Copyright Notification
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The copyright and the foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 2008.
All rights reserved.
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DECT , PLUGTESTS , UMTS , TIPHON , the TIPHON logo and the ETSI logo are Trade Marks of ETSI registered
for the benefit of its Members.
TM
3GPP is a Trade Mark of ETSI registered for the benefit of its Members and of the 3GPP Organizational Partners.
ETSI
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SIST-V ETSI/EG 202 396-1 V1.2.2:2009
3 ETSI EG 202 396-1 V1.2.2 (2008-09)
Contents
Intellectual Property Rights.5
Foreword.5
Introduction .5
1 Scope.6
2 References.6
2.1 Normative references.7
2.2 Informative references.7
3 Definitions and abbreviations.8
3.1 Definitions.8
3.2 Abbreviations.8
4 Overview of existing methods for realistic sound reproduction.8
4.1 Introduction.8
4.2 Surround Sound Techniques.9
4.3 IOSONO.10
4.4 Eidophonie .10
4.5 Four-loudspeaker arrangement for playback of binaurally recorded signals.11
4.6 NTT Background-Noise Database.12
4.7 General conclusions.12
5 Recording arrangement .13
5.1 Binaural equalization.13
5.2 The equalization procedure .13
6 Loudspeaker Setup for Background Noise Simulation .15
6.1 Test Room Requirements .15
6.2 Loudspeaker Positioning.15
6.3 Equalization and Calibration .16
6.4 Accuracy of the reproduction arrangement .21
6.4.1 Comparison between original sound field and simulated sound field.21
6.4.2 Displacement of the test arrangement in the simulated sound field.22
6.4.3 Transmission of background noise: Comparison of terminal performance in the original sound field
and the simulated sound field .24
7 Background Noise Simulation in cars .28
7.1 General setup.28
7.2 Recording arrangement.29
7.2.1 Recording setup with the terminal's microphone.29
7.2.2 Recording setup with a pair of cardioid microphones.30
7.3 Equalization and Calibration with the terminal's microphone.30
7.4 Equalization and Calibration with a pair of cardioid microphones .35
7.5 Accuracy of the reproduction arrangement .40
7.5.1 Comparison between original sound field and simulated sound field.40
7.5.2 Transmission of background noise: Comparison of terminal performance in the original sound field
and the simulated sound field .41
8 Background Noise Database .43
8.1 Binaural signals.44
8.2 Stereophonic signals.46
Annex A: Comparison of Tests in Sending Direction and D-Values Conducted in Different
Rooms.47
A.1 Test Setup.47
A.2 Results of the Tests .48
A.2.1 Sending Frequency Response Characteristics and SLR .48
ETSI
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4 ETSI EG 202 396-1 V1.2.2 (2008-09)
A.2.2 D-Value with Pink Noise .48
A.2.3 D-Value with Cafeteria Noise .49
A.3 Conclusions.49
Annex B: Graphs.50
History .58
ETSI
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SIST-V ETSI/EG 202 396-1 V1.2.2:2009
5 ETSI EG 202 396-1 V1.2.2 (2008-09)
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 Processing, Transmission and Quality
Aspects (STQ).
The present document is part 1 of a multi-part deliverable covering Speech Processing, Transmission and Quality
Aspects (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".
Introduction
Background noise is present in most of the conversations today. Background noise may impact the speech
communication performance to terminal and network equipment significantly. Therefore testing and optimization of
such equipment is necessary using realistic background noises. Furthermore reproducible conditions for the tests are
required which can be guaranteed only under lab type condition.
The present document addresses this issue by describing a methodology for recording and playback of background
noises under well defined and calibratable conditions in a lab-type environment. Furthermore a database with real
background noises is included.
ETSI
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6 ETSI EG 202 396-1 V1.2.2 (2008-09)
1 Scope
The quality of background noise transmission is an important factor, which significantly contributes to the perceived
overall quality of speech. Existing and even more the new generation of terminals, networks and system configurations
including broadband services can be greatly improved with a proper design of terminals and systems in the presence of
background noise. The present document:
• describes a noise simulation environment using realistic background noise scenarios for laboratory use;
• contains a database including the relevant background noise samples for subjective and objective evaluation.
The present document provides information about the recording techniques needed for background noise recordings and
discusses the advantages and drawbacks of existing methods. The present document describes the requirements for
laboratory conditions. The loudspeaker setup and the loudspeaker calibration and equalization procedure are described.
The simulation environment specified can be used for the evaluation and optimization of terminals and of complex
configurations including terminals, networks and other configurations. The main application areas should be: office,
home and car environment.
The setup and database as described in the present document are applicable for:
• Objective performance evaluation of terminals in different (simulated) background noise environments.
• Speech processing evaluation by using the pre-processed speech signal in the presence of background noise,
recorded by a terminal.
• Subjective evaluation of terminals by performing conversational tests, specific double talk tests or talking and
listening tests in the presence of background noise.
• Subjective evaluation in third party listening tests by recording the speech samples of terminals in the presence
of background noise.
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific.
• For a specific reference, subsequent revisions do not apply.
• Non-specific reference may be made only to a complete document or a part thereof and only in the following
cases:
- if it is accepted that it will be possible to use all future changes of the referenced document for the
purposes of the referring document;
- for informative references.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
For online referenced documents, information sufficient to identify and locate the source shall be provided. Preferably,
the primary source of the referenced document should be cited, in order to ensure traceability. Furthermore, the
reference should, as far as possible, remain valid for the expected life of the document. The reference shall include the
method of access to the referenced document and the full network address, with the same punctuation and use of upper
case and lower case letters.
NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee
their long term validity.
ETSI
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SIST-V ETSI/EG 202 396-1 V1.2.2:2009
7 ETSI EG 202 396-1 V1.2.2 (2008-09)
2.1 Normative references
The following referenced documents are indispensable for the application of the present document. For dated
references, only the edition cited applies. For non-specific references, the latest edition of the referenced document
(including any amendments) applies.
Not applicable.
2.2 Informative references
The following referenced documents are not essential to the use of the present document but they assist the user with
regard to a particular subject area. For non-specific references, the latest version of the referenced document (including
any amendments) applies.
[i.1] Surround Sound Past, Present, and Future: "A history of multichannel audio from mag stripe to
Dolby Digital", Joseph Hull - Dolby Laboratories Inc.
NOTE: See at http://www.dolby.com/assets/pdf/tech_library/2_Surround_Past.Present.pdf.
[i.2] AES preprint 3332 (1992): "Improved Possibilities of Binaural Recording and Playback
Techniques", K. Genuit, H.W. Gierlich; U. Künzli.
NOTE: See at http://www.aes.org/e-lib/browse.cfm?elib=6801.
[i.3] AES preprint 3732 (1993): "A System for the Reproduction Technique for Playback of Binaural
Recordings", N. Xiang, K. Genuit, H.W. Gierlich.
NOTE: See at http://www.aes.org/e-lib/browse.cfm?elib=6501.
[i.4] NTTAT Database: "Ambient Noise Database CD-ROM".
NOTE: See at http://www.ntt-at.com/products_e/noise-DB/index.html.
[i.5] ISO 11904-1: "Acoustics - Determination of sound immission from sound sources placed close to
the ear - Part 1: Technique using a microphone in a real ear (MIRE technique)".
[i.6] Spatial Hearing: "The psychophysics of human sound localization", J. Blauert.
[i.7] ITU-T Recommendation P.57: "Artificial ears".
[i.8] ITU-T Recommendation P.58: "Head and torso simulator for telephonometry".
[i.9] ITU-T Recommendation P.340: "Transmission characteristics and speech quality parameters of
hands-free terminals".
[i.10] ITU-T recommendation P.64: "Determination of sensitivity/frequency characteristics of local
telephone systems".
[i.11] ITU-T Recommendation G.722: "7 kHz audio-coding within 64 kbit/s".
[i.12] Genuit, K.: "A Description of the Human Outer Ear Transfer Function by Elements of
Communication Theory (No. B6-8)". Proceedings of the 12th International Congress on Acoustics.
Toronto published on behalf of the Technical Program Committee by the Executive Committee of
the 12th International Congress on Acoustics.
[i.13] IEC 60050-722: "International Electrotechnical Vocabulary - Chapter 722: Telephony".
[i.14] "Wellenfeldsynthese - Eine neue Dimension der 3D-Audiowiedergabe"; Fernseh- und Kino-
Technik, Nr. 11/2002, pp. 735-738.
[i.15] http://www.iosono-sound.de.
[i.16] "Ein neues Verfahren der raumbezogenen Stereophonie mit verbesserter Übertragung der
Rauminformation"; P. Scherer, Rundfunktechnische Mitteilungen, 1977, pp. 196-204.
ETSI
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8 ETSI EG 202 396-1 V1.2.2 (2008-09)
[i.17] ETSI EG 202 396-1 (V.1.1.2): "Speech quality performance in the presence of background noise;
Part 1: Background noise simulation technique and background noise database".
[i.18] ETSI TS 151 010-1: "Digital cellular telecommunications system (Phase 2+); Mobile Station (MS)
conformance specification; Part 1: Conformance specification (3GPP TS 51.010-1)".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
crosstalk: appearance of undesired energy in a channel, owing to the presence of a signal in another channel, caused
by, for example induction, conduction or non linearity
NOTE: See IEC 60050-722 [i.13].
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
CD Compact Disc
FFT Fast Fourier Transform
FIR Finite Impulse Response
HATS Head And Torso Simulator
IIR Infinite Impulse Response
MIRE Microphone In Real Ear
NTT Nippon Telegraph and Telephone Corporation
SLR Send Loudness Rating
VHF Very High Frequency
4 Overview of existing methods for realistic sound
reproduction
4.1 Introduction
In general the existing methods for close to original sound recording and reproduction aimed for different applications:
• Techniques intending to reproduce the actual sound field.
• Techniques providing hearing adequate (ear related) signals in the human ear canal.
• Techniques generating artificial acoustical environments.
Within this clause the different methods are briefly described and their applicability for close to original sound-filed
reproduction is discussed. A variety of methods have been studied, in the following a summary of the most important
ones relevant to the present document is given. The different methods were analyzed on the basis of the following
requirements:
• The background noise recording technique should be:
- easy to use;
- easy to calibrate;
- capable of wideband recording;
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- available at reasonable costs;
- mostly compatible to existing standards and procedures used in telecommunications testing;
- applicable to different environments (at least office, home and car).
• The background noise simulation arrangement should:
- be easy to setup;
- not require any specific acoustical treatment for the simulation requirement;
- provide a mostly realistic background noise simulation for all typical background noises faced with in
telecommunication applications;
- be easy to calibrate;
- be mostly insensitive against the positioning of (test)-objects in the simulated sound field;
- be applicable to all typical terminals used in telecommunication;
- be available at reasonable costs.
4.2 Surround Sound Techniques
The basics of surround techniques are found in cinema applications. The virtual image provided by stereophonic
presentation of sounds seemed not to be sufficient for the large screen display in cinema. In the 1950s 4-channel and
6-channel soundtracks recorded on magnetic stripes associated to the films were developed, 4-channel and 6-channel
loudspeaker systems were installed in cinemas to reproduce the multichannel sounds. The newer techniques were
mostly developed and marketed by Dolby® [i.1]: Dolby Surround, Dolby Surround Pro Logic, Dolby Digital and Dolby
Digital Surround are examples for the techniques introduced more recently. The most common configuration is the
"5.1-configuration" used in cinema but in home applications as well. The reproduction system consists of left and right
channel, a centre speaker, two surround channels (left and right, arranged in the back of the listener) and a low
frequency channel for low frequency effects.
The aim of all surround system is to create an artificial acoustical image in the recording studio rather than recording a
real acoustical scenario and providing true to original playback possibilities.
On the recording side special surround encoders are used allowing the 5-channel signal to be encoded from a special
mixing console to the 5.1 digital data stream. The playback system consists of a special decoder allowing to separate the
5 channels again and distribute them on the 5.1 loudspeaker playback system. The systems are mono and stereo
compatible and can handle the older 4 channel surround techniques by a specific decoder.
Applications:
Typical applications for surround systems are cinemas and home theatres. The source material is produced by
professional recording studios using multi-channel mixing consoles and specific 5.1 decoding techniques. In mostly all
cases virtual environments are created which support the visual image by an appropriate acoustical image.
Conclusion:
Surround techniques are designed for creating acoustical images rather than for close to original recording and
reproduction. Although the spatial impression provided by surround techniques is sometimes remarkable the acoustical
image created is always artificial. Due to the lack of easy to use recording techniques allowing a spatial recording of a
sound field surround sound techniques are not suitable for creation of a background noise database with realistic
background noises and calibrated background noise simulation in a lab.
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4.3 IOSONO
The IOSONO® sound system (see [i.14] and [i.15]) is based on the Wave-Field Synthesis. It employs Huygens
principle of wave theory. Applied to acoustics this principle means that it is possible to reproduce any form of wave
front with an array of loudspeakers, so that virtual sound sources can be placed anywhere within a listening area. For
practical use it is necessary to position loudspeakers all-round the playback room. In order to generate realistic sound
fields the input signal for each loudspeaker has to be calculated separately. For this purpose each single sound source
(e.g. voices) has to be recorded individually. If the recordings are done in a room, the characteristics (like reverberation)
of the recording room also have to be recorded separately. All resulting sound tracks are then mixed and manipulated
during the post-editing process and the reproduction.
The natural and realistic spatial sound reproduction is then achieved in a wide area of the play back room. Common 5.1
stereo systems achieve a "realistic" sound reproduction only in a small area of the reproduction room.
Applications:
Typical applications are sound systems for home use, cinemas and other entertainment events. The IOSONO sound
system is also able to play back recordings made in common stereo or 5.1 stereo techniques.
Conclusion:
The drawbacks of this method are the components needed: a sophisticated recording system, a powerful computing unit
for real-time mixing the large number of recorded sound tracks and the number of loudspeakers that have to be installed
in the listening room. In a common size cinema for example about 200 loudspeakers are needed.
The advantage is that with the IOSONO sound system a very realistic sound reproduction is possible, but it requires an
enormous effort, which is too high for daily use in laboratories.
4.4 Eidophonie
This method (see [i.16]) was developed for realistic sound reproduction using the VHF transmission technique. The
main principle is to separate the base signal from the part of the signal, which contains the information about the
direction of sound incidence.
st
For recording a 1 order gradient microphone with a cardioid directivity is used. During the recordings its directivity
rotates with 38 kHz in the recording plane. This "turning microphone" provides an amplitude-modulated signal at its
electrical output. The resulting side bands are out of the transmitted frequency range. But these side bands contain the
information of the direction of sound incidence. Using the VHF- transmission techniques this phase information can be
nd
transmitted within the 2 audio-frequency channel.
The sound reproduction is made by a spatial demodulation: a switch is positioned before each loudspeaker and each
switches synchronously with the turning directivity. So a low pass filtered short-term section of the signal containing
the information of the direction of sound incidence is played back on each loudspeaker. The loudspeakers are positioned
all around the playback room.
Applications:
Eidophonie was developed to provide a realistic sound environment using a signal received from a VHF broadcast
station. With this technique the common stereo sound reproduction should be improved. Nevertheless Eidophonie is
also compatible to common mono and stereo recordings.
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Conclusion:
Benefits of this system are that three loudspeakers are sufficient to produce a realistic sound field. Using more
loudspeakers (e.g. 16) the spatial sound reproduction gets more and more independent from the listening position.
Moreover the independency of the transmitted sound from the acoustics of the reproduction room increases with the
number of loudspeakers used. But there are significant limitations of the method: The microphone directivity is
frequency dependent and not ideal. Therefore the interference between the different channels is created. A second
problem is the loudspeaker directivity, which does not fit the microphone dir
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