SIST ES 201 377-2 V1.4.1:2010

ETSI Standard
Speech and multimedia Transmission Quality (STQ);
Specification and measurement of
speech transmission quality;
Part 2: Mouth-to-ear speech transmission
quality including terminals
2 ETSI ES 201 377-2 V1.4.1 (2009-12)

Reference
RES/STQ-00105-2
Keywords
network, QoS, quality, speech, terminal, testing,
transmission
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3 ETSI ES 201 377-2 V1.4.1 (2009-12)

Contents
Intellectual Property Rights . 5
Foreword . 5
Introduction . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 7
2.2 Informative references . 9
3 Definitions and abbreviations . 9
3.1 Definitions . 9
3.2 Abbreviations . 11
4 General considerations for end-to-end speech quality evaluations . 12
5 Test configurations . 16
5.1 Test setup for terminals . 16
5.1.1 Setup for handset terminals . 17
5.1.2 Setup for headset terminals . 17
5.1.3 Setup for hands-free type terminals and loudspeaking terminals. 18
5.1.4 Position and calibration of HATS . 18
5.2 Setup of the electrical interfaces . 18
5.3 Test signals . 19
5.4 Accuracy of test equipment . 19
6 Test conditions . 20
6.1 Acoustic environment . 20
6.2 Network conditions, general . 20
6.2.1 Network conditions, PSTN . 21
6.2.2 Network conditions, packet based transmission . 21
6.2.3 Network conditions, GSM mobile and 3G mobile . 22
6.2.3.1 Speech levels . 25
6.2.3.2 Echo control . 25
6.2.3.3 Radio network and radio network features . 26
7 Measurement of "standard" parameters . 28
7.1 Sending frequency response . 29
7.2 Receiving frequency response . 29
7.3 Overall frequency response . 29
7.4 Sending (and connection) loudness rating . 30
7.5 Receiving (and connection) loudness rating . 30
7.6 Overall loudness rating . 31
7.7 Sidetone masking rating . 32
7.8 Listener sidetone . 32
7.9 Measurement and calculation of the value of the D-factor (DelSM) . 33
7.10 Delay . 34
7.10.1 Delay in sending direction . 34
7.10.2 Delay in receiving direction . 34
7.10.3 Overall delay . 35
7.11 Terminal coupling loss . 35
7.12 Talker echo loudness rating . 36
7.13 Weighted echo path loss . 37
7.14 Distortion . 37
7.14.1 Distortion in sending . 37
7.14.2 Distortion in receiving . 38
7.14.3 Overall distortion . 39
7.15 Sensitivity against out-of-band signals in sending . 40
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4 ETSI ES 201 377-2 V1.4.1 (2009-12)

7.16 Spurious out-of-band signals in receiving . 41
8 Advanced measurement procedures, taking into account the conversational situation. 42
8.1 Measurement setup for objective tests. 43
8.2 Practical realization of test signals . 43
8.3 Quality of background noise transmission . 43
8.3.1 Test setup for background noise transmission tests . 44
8.3.2 Background noise transmission with far end speech . 44
8.3.3 Background noise transmission with near end speech . 45
8.3.4 Speech transmission quality with near end background noise . 46
8.4 Double talk performance . 47
8.5 Switching characteristics . 48
8.6 Level adjustments by companding or AGC . 51
8.7 Additional echo disturbances . 52
8.8 Speech sound quality . 52
Annex A (informative): Bibliography . 54
History . 55

ETSI
5 ETSI ES 201 377-2 V1.4.1 (2009-12)

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 Standard (ES) has been produced by ETSI Technical Committee Speech and multimedia Transmission
Quality (STQ).
The present document provides technical requirements for assessing the conversational speech quality performance
parameters from mouth-to-ear independent of the technology used.
The present document is part 2 of a multi-part deliverable covering the specification and measurement of speech
transmission quality, as identified below:
EG 202 377-1: "Introduction to objective comparison measurement methods for one-way speech quality across
networks";
ES 202 377-2: "Mouth-to-ear speech transmission quality including terminals";
EG 202 377-3: "Non-intrusive objective measurement methods applicable to networks and links with classes of
services".
Introduction
Various standards within ETSI, ITU, TIA and other standardization organizations describe performance requirements
for different types of terminals, networks and network components. In each standard emphasis is given typically only to
a part of the overall connection. The speech quality perceived by the user however is influenced by any component in
the overall connection. In modern complex network and end-to-end (mouth-to-ear) configurations there is no guarantee
for a sufficient overall performance if only the individual components conform to their relevant standards. Furthermore
many of the existing testing specifications still assume a linear and time invariant behaviour of the components which
due to complex signal processing in most of the modern communication devices can no longer be expected. Only a few
standards exist which describe test procedures and requirements for the interaction of different network components
with the different types of terminals.
The present document addresses the mouth-to-ear speech quality taking into account all conversational aspects. An
overview about different network/terminal configurations and their specific impact on speech quality is given. The
present document describes testing procedures and setups for different configurations.
ETSI
6 ETSI ES 201 377-2 V1.4.1 (2009-12)

1 Scope
The present document addresses mouth-to-ear (i.e. end-to-end speech quality for 3,1 kHz telephony). It both:
a) summarizes and gives guidance about the main factors that affect speech quality in end-to-end scenarios; and
b) specifies test methods for end-to-end speech quality testing.
The test methods can be used both for the complete transmission from mouth-to-ear and also for testing individual
sections of a connection.
The end-end (mouth-to-ear) test methods specified in the present document are independent of the technology used in
the network and the terminals. However when practical considerations make it necessary to test at electrical interfaces
within or between equipments the present document explains how to handle the most common current technologies.
The present document is designed to be used by:
• terminal and terminal component (e.g. soundcard) developers who wish to evaluate the end-to-end
performance of networks and their terminals (or components); or
• network designers who wish to evaluate the end-to-end performance of their networks with typical terminals.
And therefore it gives advice on how networks and representative terminals (respectively) can be selected or simulated
for use in the end-to-end tests.
The test methods described allow the evaluation of all conversational situations such as single talk and double talk by
means of objective procedures.
The present document takes account of:
a) all types of terminals, including handsets, headsets and dedicated hands-free arrangements such as are
provided with some mobile terminals and PC based terminals;
b) both circuit switched and packet based networks, including IP and ATM.
The present document is not generally suitable for wideband telephony or other forms of wideband communication
although the parametric approach and the measurement procedures for some of the parameters described in the present
document are applicable for wideband communication as well.
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.
NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee
their long term validity.
ETSI
7 ETSI ES 201 377-2 V1.4.1 (2009-12)

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.
[1] ITU-T Recommendation G.821: "Error performance of an international digital connection
operating at a bit rate below the primary rate and forming part of an Integrated Services Digital
Network".
[2] Gierlich, H.W.; Kettler, F., Diedrich, E.: "Speech Quality Evaluation of Hands-Free Telephones
During Double Talk: New Evaluation Methodologies"; EUSIPCO 1998, Proceedings, Vol. II.
[3] Gierlich, H.W. (December 1996): "The auditory perceived quality of hands-free telephones:
Auditory judgements, instrumental measurements and their relationship", Speech Communication
20, pp. 241-254.
[4] IEC 61260: "Electroacoustics - Octave-band and fractional-octave-band filters".
[5] IEC 61672 (all parts): "Electroacoustics - Sound level meters".
[6] ISO 3 (1973): "Preferred numbers - Series of preferred numbers".
[7] ITU-T Recommendation G.107: "The E-model, a computational model for use in transmission
planning".
[8] ITU-T Recommendation G.111: "Loudness ratings (LRs) in an international connection".
[9] ITU-T Recommendation G.122: "Influence of national systems on stability and talker echo in
international connections".
[10] ITU-T Recommendation G.131: "Talker echo and its control".
[11] ITU-T Recommendation G.168: "Digital network echo cancellers".
[12] ITU-T Recommendation G.712: "Transmission performance characteristics of pulse code
modulation channels".
[13] ITU-T Recommendation O.131: "Quantizing distortion measuring equipment using a
pseudo-random noise test signal".
[14] ITU-T Recommendation O.132: "Quantizing distortion measuring equipment using a sinusoidal
test signal".
[15] ITU-T Recommendation P.340: "Transmission characteristics and speech quality parameters of
hands-free terminals".
[16] ITU-T Recommendation P.380: "Electro-acoustic measurements on headsets".
[17] ITU-T Recommendation P.50: "Artificial voices".
[18] ITU-T Recommendation P.501: "Test signals for use in telephonometry".
[19] ITU-T Recommendation P.502: "Objective test methods for speech communication systems using
complex test signals".
[20] ITU-T Recommendation P.51: "Artificial mouth".
[21] ITU-T Recommendation P.57: "Artificial ears".
[22] ITU-T Recommendation P.58: "Head and torso simulator for telephonometry".
[23] ITU-T Recommendation P.581: "Use of Head and Torso Simulator (HATS) for hands-free
terminal testing".
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8 ETSI ES 201 377-2 V1.4.1 (2009-12)

[24] ITU-T Recommendation P.64: "Determination of sensitivity/frequency characteristics of local
telephone systems".
[25] ITU-T Recommendation P.79 and Corrigendum 2 (2001): "Calculation of loudness ratings for
telephone sets".
[26] ITU-T Recommendation P.800: "Methods for subjective determination of transmission quality".
[27] ITU-T Recommendation P.810: "Modulated noise reference unit (MNRU)".
[28] ITU-T Recommendation P.830: "Subjective performance assessment of telephone-band and
wideband digital codecs".
[29] ITU-T Recommendation P.831: "Subjective performance evaluation of network echo cancellers".
[30] ITU-T Recommendation P.832: "Subjective performance evaluation of hands-free terminals".
[31] ITU-T Recommendation P.862: "Perceptual evaluation of speech quality (PESQ), an objective
method for end-to-end speech quality assessment of narrow-band telephone networks and speech
codecs".
[32] ITU-T Recommendation Y.1541: "Network performance objectives for IP-based services".
[33] ITU-T COM12-42 (Federal Republic of Germany, January 1998): "Listening only test results for
hands-free telephones and their dependence upon room surroundings".
[34] TIA/EIA 810-A: "Telecommunications - Telephone Terminal Equipment-Transmission
Requirements for Narrowband".
[35] ITU-T Recommendation P.59: "Artificial conversational speech".
[36] ITU-T Recommendation G.711: "Pulse code modulation (PCM) of voice frequencies".
[37] ETSI TS 100 961: "Digital cellular telecommunications system (Phase 2+) (GSM); Full rate
speech; Transcoding (GSM 06.10 Release 1998)".
[38] ETSI EN 300 969: "Digital cellular telecommunications system (Phase 2+) (GSM); Half rate
speech; Half rate speech transcoding (GSM 06.20 version 8.0.1 Release 1999)".
[39] ETSI EN 300 726: "Digital cellular telecommunications system (Phase 2+) (GSM); Enhanced Full
Rate (EFR) speech transcoding (GSM 06.60 version 8.0.1 Release 1999)".
[40] ETSI EN 300 903: "Digital cellular telecommunications system (Phase 2+) (GSM); Transmission
planning aspects of the speech service in the GSM Public Land Mobile Network (PLMN) system
(GSM 03.50 version 8.1.1 Release 1999)".
[41] ISO 9614 (all parts): "Acoustics - Determination of sound power levels of noise sources using
sound intensity".
[42] Inter-Noise'96: "Evaluation of Acoustic-Quality Based on a Relative Approach", K. Genuit: 25th
Anniversary Congress Liverpool, 30.07-02.08.1996, Conference Proceedings
(Book 6 / ISBN: 1 873082 90 8), pp. 3233-3238, Liverpool, England.
[43] ITU-T Recommendation G.726: "40, 32, 24, 16 kbit/s Adaptive Differential Pulse Code
Modulation (ADPCM)".
[44] ETSI ES 202 737: "Speech and multimedia Transmission Quality (STQ); Transmission
requirements for narrowband VoIP terminals (handset and headset) from a QoS perspective as
perceived by the user".
[45] ETSI ES 202 738: "Speech and multimedia Transmission Quality (STQ); Transmission
requirements for narrowband VoIP loudspeaking and handsfree terminals from a QoS perspective
as perceived by the user".
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9 ETSI ES 201 377-2 V1.4.1 (2009-12)

[46] ETSI ES 202 739: "Speech and multimediaTransmission Quality (STQ); Transmission
requirements for wideband VoIP terminals (handset and headset) from a QoS perspective as
perceived by the user".
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] ETSI EG 201 377-1: "Speech and multimedia Transmission Quality (STQ); Specification and
measurement of speech transmission quality; Part 1: Introduction to objective comparison
measurement methods for one-way speech quality across networks".
[i.2] ETSI TR 101 110: "Digital cellular telecommunications system (Phase 2+) (GSM);
Characterisation, test methods and quality assessment for handsfree Mobile Stations (MSs)
(GSM 03.58)".
[i.3] ETSI EG 201 050: "Speech Processing, Transmission and Quality Aspects (STQ); Overall
Transmission Plan Aspects for Telephony in a Private Network".
[i.4] ETSI TBR 008: "Integrated Services Digital Network (ISDN); Telephony 3,1 kHz teleservice;
Attachment requirements for handset terminals".
[i.5] ETSI TR 102 251: "Speech Processing, Transmission and Quality Aspects (STQ); Anonymous
Test Report from 2nd Speech Quality Test Event 2002".
[i.6] 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.7] ETSI EG 202 396-3: "Speech Processing, Transmission and Quality Aspects (STQ); Speech
Quality performance in the presence of background noise Part 3: Background noise transmission -
Objective test methods".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
Acoustic Reference Level (ARL): acoustic level at MRP which results in a -10 dBm0 output at the digital interface
artificial ear: device for the calibration of earphones incorporating an acoustic coupler and a calibrated microphone for
the measurement of the sound pressure and having an overall acoustic impedance similar to that of the median adult
human ear over a given frequency band
codec: combination of an analogue-to-digital encoder and a digital-to-analogue decoder operating in opposite directions
of transmission in the same equipment
diffuse field equalization: equalization of the HATS sound pick-up, equalization of the difference, in dB, between the
spectrum level of the acoustic pressure at the ear Drum Reference Point (DRP) and the spectrum level of the acoustic
pressure at the HATS Reference Point (HRP) in a diffuse sound field with the HATS absent (see also ITU-T
Recommendation P.58 [22]) using the reverse nominal curve given in table 3 of ITU-T Recommendation P.58 [22]
ear-Drum Reference Point (DRP): point located at the end of the ear canal, corresponding to the ear-drum position
Ear Reference Point (ERP): virtual point for geometric reference located at the entrance to the listener's ear,
traditionally used for calculating telephonometric loudness ratings
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10 ETSI ES 201 377-2 V1.4.1 (2009-12)

electric power and noise levels: the following electric power and noise level units are used in the present document:
dBm0: The absolute power level at a digital reference point of the same signal that would be measured as
the absolute power level, in dBm, if the reference point was analogue. The absolute power in dBm
is defined as 10 log (power in mW/1 mW). When the impedance is 600 ohm resistive, dBm can be
referred to a voltage of 0,775 volts, which results in a reference active power of 1 mW. Note that
0 dBm0 is not the maximum digital code. For the L16-256 wideband codec adopted by
TIA TR-41, 0 dBm0 is 3,14 dB below digital full scale.
end-to-end: endpoints of a (telephone) connection between two subscribers, either between the NTPs (e.g. for bearer
services), or for speech communication between mouth and ear
G-MOS-LQOw: measure of the overall transmission quality in the presence of background noise (objective, wideband)
Head And Torso Simulator (HATS) for telephonometry: manikin extending downward from the top of the head to
the waist, designed to simulate the sound pick-up characteristics and the acoustic diffraction produced by a median
human adult and to reproduce the acoustic field generated by the human mouth
NOTE: HATS conforms to ITU-T Recommendation P.58 [22].
HATS position: correct handset position for measuring sensitivity and frequency response characteristics
NOTE: The HATS position has been shown to be essentially identical to the LRGP (loudness rating guard-ring
position) position, except for the mouth simulator direction, which has been corrected with a 19 degrees
downwards rotation to more closely match real talkers. For handsets with omnidirectional microphones,
measurements on the two heads may differ slightly, typically less than 1 dB. For handsets with directional
or noise-cancelling microphones, the differences will be larger, and the HATS position will give the more
realistic results. See ITU-T Recommendation P.64 [24] (annexes D and E) and EUSIPCO 1998,
Proceedings, Vol. II. [2].
Hands-Free Reference Point (HFRP): point located on the axis of the artificial mouth, at 50 cm from the outer plane
of the lip ring, where the level calibration is made under free-field conditions
HATS Hands-Free Reference Point (HATS-HFRP): corresponds to a reference point "n" from ITU-T
Recommendation P.58 [22]: "n" shall be one of the points numbered from 11 to 17 and defined in table 6a/P.58
(coordinates of far field front point).
NOTE: The HATS HFRP depends on the location(s) of the microphones of the terminal under test: the
appropriate axis lip-ring/HATS HFRP is as close as possible to the axis lip-ring/HFT microphone under
test. (see ITU-T Recommendation P.581 [23]).
mouth-to-ear: endpoints of a telephone connection between two subscribers between mouth and ear
Mouth Reference Point (MRP): point located on axis and 25 mm in front of the lip plane of a mouth simulator
N-MOS-LQOw: measure of the noise transmission quality in the presence of speech with background noise (objective,
wideband)
pinna simulator: device which has the approximate shape and dimensions of a median adult human pinna
reference volume control setting: receive volume control setting which results in the Receive Loudness Rating (RLR)
closest to the target value (centre of the RLR tolerance range)
NOTE: There may be separate settings for handset, headset and hands-free modes.
S-MOS-LQOw: measure of the speech transmission quality in the presence of background noise (objective, wideband)
sound pressure levels: value expressed as a ratio of the pressure of a sound to a reference pressure
NOTE 1: The following sound level units are used in the present document:
dBPa: The sound pressure level, in decibels, of a sound is 20 times the logarithm to the base 10 of the
ratio of the pressure of this sound to the reference pressure of 1 Pascal (Pa).
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11 ETSI ES 201 377-2 V1.4.1 (2009-12)

NOTE 2: 1 Pa = 1 N/m .
dBSPL: The sound pressure level, in decibels, of a sound is 20 times the logarithm to the base 10 of
-5 2
the ratio of the pressure of this sound to the reference pressure of 2 × 10 N/m (0 dBPa
corresponds to 94 dBSPL).
dB(A): The A-weighted sound level is the sound pressure level e.g. in dBSPL, weighted by use of
metering characteristics and A-weighting specified in IEC 61672 [5].
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
ARL Acoustic Reference Level
BER Bit Error Rate
BSC Base Station Controller
BTS Base Transceiver Station
C/A adjacent channel interference
C/I Carrier to Interference ratio
C/N Carrier/Noise
CSS Composite Source Signals
D D-value of terminal
dBPa decibel relative to one Pascal
dBSPL decibel Sound Pressure Level
DCME Digital Circuit Multiplication Equipment
DRP ear Drum Reference Point
DTX Discontinuous Transmission
EL Echo Loss
ERL Echo Return Loss
ERP Ear Reference Point
FER Frame Erasure Rate
GERAN GSM/EDGE Radio Access Network
G-MOS-LQOn Global mean opinion score (listening quality,objective, narrowband)
G-MOS-LQOw Global mean opinion score (listening quality,objective, wideband)
HATS Head And Torso Simulator
HFRP Hands-Free Reference Point
HFT Hands-Free Terminal
LRGP Loudness Rating Guard-ring Position
LSTR Listener SideTone Rating
LTI Linear Time Invariant
MRP Mouth Reference Point
MSC Mobile service Switching Centre
Nc circuit Noise referred to the 0 dBr-point
NLP Non-Linear Processor
N-MOS-LQOn Noise mean opinion score (listening quality,objective, narrowband)
N-MOS-LQOw Noise mean opinion score (listening quality,objective, wideband))
OLR Overall Loudness Rating
PCM Pulse Code Modulation
PESQ Perceptional Evaluation of Speech Quality
PLC Packet Loss Concealment
PLMN Public Land Mobile Network
PSTN Public Switched Telephone Network
qdu number of quantizing distortion units
RCV Residual Capital Value
RLR Receiving Loudness Rating
SLR Sending Loudness Rating
S-MOS-LQOn Speech mean opinion score (listening quality,objective, narrowband)
S-MOS-LQOw Speech mean opinion score (listening quality,objective, wideband)
SND Signal + Noise + Distortion
STMR SideTone Masking Rating
TCL Terminal Coupling Loss
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12 ETSI ES 201 377-2 V1.4.1 (2009-12)

TCLw Terminal Coupling Loss (weighted)
TELR Talker Echo Loudness Rating
TOSQA Telecommunication Objective Speech Quality Assessment
TRC TRanscoder Controller
UTRAN UMTS Terrestrial Radio Access Network
WEPL Weighted Echo Path Loss
4 General considerations for end-to-end speech quality
evaluations
When evaluation the overall speech transmission quality, networks and terminals may influence quite significantly the
speech quality of a connection: Coding, delay and processing techniques like speech echo cancellers packetizing or
DCME are mainly introduced by the network(s) but similar signal processing can be found in terminals as well. The
transfer functions and loudness ratings of a connection are mainly determined by the terminals, the background noise
and the background noise transmission are highly influenced by the terminal and the acoustical environment the
terminal is exposed to. The conversational properties which are the most important ones in a conversation are
determined by the terminal in combination with the network: double talk capability, switching characteristics, echo and
delay are dominant impairments often introduced.
In order to find the determining factors a set of subjective test procedures have been developed allowing to extract the
dominant quality aspects: Conversational test, talking and listening tests, double talk tests and listening only tests (as
described in Speech Communication 20 (pp. 241 to 254) [3] and ITU-T Recommendations P.800 [26], P.810 [27],
P.830 [28], P.831 [29] and P.832 [30]) are the basis of the parameter extraction procedure.
An overview of the methodologies is given in figures 1a to 1c.
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13 ETSI ES 201 377-2 V1.4.1 (2009-12)

Test Auditory
Performance
environment tests
parameters
Realistic Conditions
End-to-end speech
"Human Factor"
transmission quality
Conversational tests
2 subjects involved
(one at the near end of
the telephone connection,
Difficulty in
the other at the far end)
communicating
Sound quality
Double talk Annoyance caused by
echoes and switching
tests
2 subjects involved
(one at the near end of
the telephone connection,
the other at the far end) Double talk
performance
or
Talking and listening
Method of background
tests
noise transmission
1 artificial head used
(at the near end of the
telephone connection),
1 subject involved
Speech level variations
(at the far end), acting as vs. time
listener and talker
Comparison of individual
parameters under defined
conditions
Listening-only
Classification of
tests
disturbances
2 artificial heads used
(one at the near end of
the telephone connection,
Measurement conditions
the other at the far end)
(exactly defined and
Database for
1 subject as "observer"
identical for each tests
further tests
and reproducible)
T1212320-00
NOTE: The assignment of "near end" and "far end" is chosen according to the E-model (ITU-T Recommendation
G.107 [7]).
Figure 1a: Overview of test methods used for subjective evaluation - direct parameter access
ETSI
Increasing reality of the testing
Increasing comparability, more analytic

14 ETSI ES 201 377-2 V1.4.1 (2009-12)

Test Auditory
Performance
environment tests
parameters
Realistic Conditions
End-to-end speech
"Human Factor"
transmission quality
Conversational tests
2 subjects involved
(one at the near end of
the telephone connection,
Difficulty in
the other at the far end)
communicating
Sound quality
Double talk Annoyance caused by
echoes and switching
tests
2 subjects involved
(one at the near end of
the telephone connection,
the other at the far end) Double talk
performance
or
Talking and listening
Method of background
tests
noise transmission
1 artificial head used
(at the near end of the
telephone connection),
1 subject involved
Speech level variations
(at the far end), acting as vs. time
listener and talker
Comparison of individual
parameters under defined
conditions
Listening-only
Classification of
tests
disturbances
2 artificial heads used
(one at the near end of
the telephone connection,
Measurement conditions
the other at the far end)
(exactly defined and
Database for
1 subject as "observer"
identical for each tests
further tests
and reproducible)
T1212330-00
NOTE: The assignment of "near end" and "far end" is chosen according to the E-model (ITU-T Recommendation
G.107 [7]).
Figure 1b: Overview about test methods used for subjective evaluation-
parameter access via interviews
ETSI
Increasing reality of the testing
Increasing comparability, more analytic

15 ETSI ES 201 377-2 V1.4.1 (2009-12)

Test Auditory
Performance
environment tests
parameters
Realistic Conditions
End-to-end speech
"Human Factor"
transmission quality
Conversational tests
2 subjects involved
(one at the near end of
the telephone connection,
Difficulty in
the other at the far end)
communicating
Sound quality
Double talk Annoyance caused by
echoes and switching
tests
2 subjects involved
(one at the near end of
the telephone connection,
the other at the far end) Double talk
performance
or
Talking and listening
Method of background
tests
noise transmission
1 artificial head used
(at the near end of the
telephone connection),
1 subject involved Speech level variations
(at the far end), acting as vs. time
listener and talker
Comparison of individual
parameters under defined
conditions
Listening-only
Classification of
tests
disturbances
2 artificial heads used
(one at the near end of
the telephone connection,
Measurement conditions
the other at the far end)
(exactly defined and
Database for
1 subject as "observer"
identical for each tests
further tests
and reproducible)
T1212340-00
NOTE: The assignment of "near end" and "far end" is chosen according to the E-model (ITU-T
Recommendation G.107 [7]).
Figure 1c: Overview about test methods used for subjective evaluation -
parameter access by including reference conditions
The subjectively relevant parameters determining the "speech transmission quality" are as follows.
The overall quality is determined by:
• Delay and echo.
• Sound quality.
• Quality of background noise transmission at idle, in single talk and double talk conditions.
ETSI
Increasing reality of the testing
Increasing comparability, more analytic

16 ETSI ES 201 377-2 V1.4.1 (2009-12)

• Speech level variations during single talk and double talk.
• Disturbances caused by switching during single talk and double talk (completeness of speech transmission).
• Disturbances caused by echoes during single talk and double talk.
Consequently the evaluation methods need to be divided into single talk measurements and double talk evaluations. In
addition evaluations are required during periods of silence where only background noise is present.
Since the typical test setup should include all components involved in the mouth-to-ear transmission a test arrangement
should include the terminals "attached" to a realistic substitution of a user and his typical environment. Figure 2
illustrates how a test setup from end-to-end may look like typically.

Figure 2: Typical test setup for determining the speech transmission quality from end-to-end
(mouth-to-ear) by subjective evaluation of the speech quality relevant parameters
(example for handset/hands-free communication)
Test setups as shown in figure 2 are used in auditory (subjective) tests to determine the quality aspects subjectively (see
ITU-T Recommendations P.800 [26], P.810 [27], P. 830 [28], P.831 [29] and P.832 [30]). From the evaluations in
ITU-T Recommendation P.800 [26], procedures have been derived which allow the objective testing of the relevant
parameters of terminals (or even end-to-end scenarios).
5 Test configurations
This clause describes the test setups for terminals, networks and their various combinations. Since the present document
describes the general aspects of end-to-end speech quality testing, specific test setups and configuration description are
made only in general. In case any specific description of terminal or network setups is needed (e.g. buffer sizes, type of
codecs, packet loss simulations) these descriptions need to be found in the relevant standards of such transmission
systems.
5.1 Test setup for terminals
The general access to terminals is described in figure 3. The traditional way to test handset-terminals is the
LRGP-position using Type 1 artificial ear and the artificial mouth according to ITU-T Recommendation P.51 [20].
positioned in LRGP (loudness rating guard ring position, ITU-T Recommendation P.64 [24]).The preferred acoustical
access to terminal is the most realistic simulation of the "average" subscriber. This can be made by using HATS (Head
And Torso Simulator) with appropriate ear simulation and appropriate means to fix handset, headset or hands-free
terminals in a realistic by reproducible way to the HATS. HATS is described in ITU-T Recommendation P.58 [22],
appropriate ears are described in ITU-T Recommendation P.57 [21] (Type 3.3 and Type 3.4 ear), a proper positioning
of handsets in realistic conditions is found in ITU-T Recommendation P.64 [24], the test setups for various types of
hands-free terminals can be found in ITU-T Recommendation P.581 [23].
The preferred way of testing a terminal is either to connect it to a network simulator with exact defined settings and
access points or, in case of end-to-end scenarios, to connect the terminal to the "typical" network it is used in. The test
sequences are fed in either electrically, using a reference codec or using the direct signal processing approach or
acoustically using ITU-T specified devices.
ETSI
17 ETSI ES 201 377-2 V1.4.1 (2009-12)

ITU-T ITU-T
test sequences test sequenc
...

SLOVENSKI STANDARD
01-februar-2010
.DNRYRVWSUHQRVDJRYRUDLQYHþSUHGVWDYQLKYVHELQ6746SHFLILNDFLMDLQ
PHULWYHNDNRYRVWLSUHQRVDJRYRUDGHO.DNRYRVWSUHQRVDJRYRUDPHGXVWLLQ
XãHVLYNOMXþQRVWHUPLQDOL
Speech and multimediaTransmission Quality (STQ) - Specification and measurement of
speech transmission quality - Part 2: Mouth-to-ear speech transmission quality including
terminals
Ta slovenski standard je istoveten z: ES 201 377-2 Version 1.4.1
ICS:
33.040.35 Telefonska omrežja Telephone networks
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

ETSI Standard
Speech and multimedia Transmission Quality (STQ);
Specification and measurement of
speech transmission quality;
Part 2: Mouth-to-ear speech transmission
quality including terminals
2 ETSI ES 201 377-2 V1.4.1 (2009-12)

Reference
RES/STQ-00105-2
Keywords
network, QoS, quality, speech, terminal, testing,
transmission
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The copyright and the foregoing restriction extend to reproduction in all media.

© European Telecommunications Standards Institute 2009.
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.
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GSM® and the GSM logo are Trade Marks registered and owned by the GSM Association.
ETSI
3 ETSI ES 201 377-2 V1.4.1 (2009-12)

Contents
Intellectual Property Rights . 5
Foreword . 5
Introduction . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 7
2.2 Informative references . 9
3 Definitions and abbreviations . 9
3.1 Definitions . 9
3.2 Abbreviations . 11
4 General considerations for end-to-end speech quality evaluations . 12
5 Test configurations . 16
5.1 Test setup for terminals . 16
5.1.1 Setup for handset terminals . 17
5.1.2 Setup for headset terminals . 17
5.1.3 Setup for hands-free type terminals and loudspeaking terminals. 18
5.1.4 Position and calibration of HATS . 18
5.2 Setup of the electrical interfaces . 18
5.3 Test signals . 19
5.4 Accuracy of test equipment . 19
6 Test conditions . 20
6.1 Acoustic environment . 20
6.2 Network conditions, general . 20
6.2.1 Network conditions, PSTN . 21
6.2.2 Network conditions, packet based transmission . 21
6.2.3 Network conditions, GSM mobile and 3G mobile . 22
6.2.3.1 Speech levels . 25
6.2.3.2 Echo control . 25
6.2.3.3 Radio network and radio network features . 26
7 Measurement of "standard" parameters . 28
7.1 Sending frequency response . 29
7.2 Receiving frequency response . 29
7.3 Overall frequency response . 29
7.4 Sending (and connection) loudness rating . 30
7.5 Receiving (and connection) loudness rating . 30
7.6 Overall loudness rating . 31
7.7 Sidetone masking rating . 32
7.8 Listener sidetone . 32
7.9 Measurement and calculation of the value of the D-factor (DelSM) . 33
7.10 Delay . 34
7.10.1 Delay in sending direction . 34
7.10.2 Delay in receiving direction . 34
7.10.3 Overall delay . 35
7.11 Terminal coupling loss . 35
7.12 Talker echo loudness rating . 36
7.13 Weighted echo path loss . 37
7.14 Distortion . 37
7.14.1 Distortion in sending . 37
7.14.2 Distortion in receiving . 38
7.14.3 Overall distortion . 39
7.15 Sensitivity against out-of-band signals in sending . 40
ETSI
4 ETSI ES 201 377-2 V1.4.1 (2009-12)

7.16 Spurious out-of-band signals in receiving . 41
8 Advanced measurement procedures, taking into account the conversational situation. 42
8.1 Measurement setup for objective tests. 43
8.2 Practical realization of test signals . 43
8.3 Quality of background noise transmission . 43
8.3.1 Test setup for background noise transmission tests . 44
8.3.2 Background noise transmission with far end speech . 44
8.3.3 Background noise transmission with near end speech . 45
8.3.4 Speech transmission quality with near end background noise . 46
8.4 Double talk performance . 47
8.5 Switching characteristics . 48
8.6 Level adjustments by companding or AGC . 51
8.7 Additional echo disturbances . 52
8.8 Speech sound quality . 52
Annex A (informative): Bibliography . 54
History . 55

ETSI
5 ETSI ES 201 377-2 V1.4.1 (2009-12)

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 Standard (ES) has been produced by ETSI Technical Committee Speech and multimedia Transmission
Quality (STQ).
The present document provides technical requirements for assessing the conversational speech quality performance
parameters from mouth-to-ear independent of the technology used.
The present document is part 2 of a multi-part deliverable covering the specification and measurement of speech
transmission quality, as identified below:
EG 202 377-1: "Introduction to objective comparison measurement methods for one-way speech quality across
networks";
ES 202 377-2: "Mouth-to-ear speech transmission quality including terminals";
EG 202 377-3: "Non-intrusive objective measurement methods applicable to networks and links with classes of
services".
Introduction
Various standards within ETSI, ITU, TIA and other standardization organizations describe performance requirements
for different types of terminals, networks and network components. In each standard emphasis is given typically only to
a part of the overall connection. The speech quality perceived by the user however is influenced by any component in
the overall connection. In modern complex network and end-to-end (mouth-to-ear) configurations there is no guarantee
for a sufficient overall performance if only the individual components conform to their relevant standards. Furthermore
many of the existing testing specifications still assume a linear and time invariant behaviour of the components which
due to complex signal processing in most of the modern communication devices can no longer be expected. Only a few
standards exist which describe test procedures and requirements for the interaction of different network components
with the different types of terminals.
The present document addresses the mouth-to-ear speech quality taking into account all conversational aspects. An
overview about different network/terminal configurations and their specific impact on speech quality is given. The
present document describes testing procedures and setups for different configurations.
ETSI
6 ETSI ES 201 377-2 V1.4.1 (2009-12)

1 Scope
The present document addresses mouth-to-ear (i.e. end-to-end speech quality for 3,1 kHz telephony). It both:
a) summarizes and gives guidance about the main factors that affect speech quality in end-to-end scenarios; and
b) specifies test methods for end-to-end speech quality testing.
The test methods can be used both for the complete transmission from mouth-to-ear and also for testing individual
sections of a connection.
The end-end (mouth-to-ear) test methods specified in the present document are independent of the technology used in
the network and the terminals. However when practical considerations make it necessary to test at electrical interfaces
within or between equipments the present document explains how to handle the most common current technologies.
The present document is designed to be used by:
• terminal and terminal component (e.g. soundcard) developers who wish to evaluate the end-to-end
performance of networks and their terminals (or components); or
• network designers who wish to evaluate the end-to-end performance of their networks with typical terminals.
And therefore it gives advice on how networks and representative terminals (respectively) can be selected or simulated
for use in the end-to-end tests.
The test methods described allow the evaluation of all conversational situations such as single talk and double talk by
means of objective procedures.
The present document takes account of:
a) all types of terminals, including handsets, headsets and dedicated hands-free arrangements such as are
provided with some mobile terminals and PC based terminals;
b) both circuit switched and packet based networks, including IP and ATM.
The present document is not generally suitable for wideband telephony or other forms of wideband communication
although the parametric approach and the measurement procedures for some of the parameters described in the present
document are applicable for wideband communication as well.
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.
NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee
their long term validity.
ETSI
7 ETSI ES 201 377-2 V1.4.1 (2009-12)

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.
[1] ITU-T Recommendation G.821: "Error performance of an international digital connection
operating at a bit rate below the primary rate and forming part of an Integrated Services Digital
Network".
[2] Gierlich, H.W.; Kettler, F., Diedrich, E.: "Speech Quality Evaluation of Hands-Free Telephones
During Double Talk: New Evaluation Methodologies"; EUSIPCO 1998, Proceedings, Vol. II.
[3] Gierlich, H.W. (December 1996): "The auditory perceived quality of hands-free telephones:
Auditory judgements, instrumental measurements and their relationship", Speech Communication
20, pp. 241-254.
[4] IEC 61260: "Electroacoustics - Octave-band and fractional-octave-band filters".
[5] IEC 61672 (all parts): "Electroacoustics - Sound level meters".
[6] ISO 3 (1973): "Preferred numbers - Series of preferred numbers".
[7] ITU-T Recommendation G.107: "The E-model, a computational model for use in transmission
planning".
[8] ITU-T Recommendation G.111: "Loudness ratings (LRs) in an international connection".
[9] ITU-T Recommendation G.122: "Influence of national systems on stability and talker echo in
international connections".
[10] ITU-T Recommendation G.131: "Talker echo and its control".
[11] ITU-T Recommendation G.168: "Digital network echo cancellers".
[12] ITU-T Recommendation G.712: "Transmission performance characteristics of pulse code
modulation channels".
[13] ITU-T Recommendation O.131: "Quantizing distortion measuring equipment using a
pseudo-random noise test signal".
[14] ITU-T Recommendation O.132: "Quantizing distortion measuring equipment using a sinusoidal
test signal".
[15] ITU-T Recommendation P.340: "Transmission characteristics and speech quality parameters of
hands-free terminals".
[16] ITU-T Recommendation P.380: "Electro-acoustic measurements on headsets".
[17] ITU-T Recommendation P.50: "Artificial voices".
[18] ITU-T Recommendation P.501: "Test signals for use in telephonometry".
[19] ITU-T Recommendation P.502: "Objective test methods for speech communication systems using
complex test signals".
[20] ITU-T Recommendation P.51: "Artificial mouth".
[21] ITU-T Recommendation P.57: "Artificial ears".
[22] ITU-T Recommendation P.58: "Head and torso simulator for telephonometry".
[23] ITU-T Recommendation P.581: "Use of Head and Torso Simulator (HATS) for hands-free
terminal testing".
ETSI
8 ETSI ES 201 377-2 V1.4.1 (2009-12)

[24] ITU-T Recommendation P.64: "Determination of sensitivity/frequency characteristics of local
telephone systems".
[25] ITU-T Recommendation P.79 and Corrigendum 2 (2001): "Calculation of loudness ratings for
telephone sets".
[26] ITU-T Recommendation P.800: "Methods for subjective determination of transmission quality".
[27] ITU-T Recommendation P.810: "Modulated noise reference unit (MNRU)".
[28] ITU-T Recommendation P.830: "Subjective performance assessment of telephone-band and
wideband digital codecs".
[29] ITU-T Recommendation P.831: "Subjective performance evaluation of network echo cancellers".
[30] ITU-T Recommendation P.832: "Subjective performance evaluation of hands-free terminals".
[31] ITU-T Recommendation P.862: "Perceptual evaluation of speech quality (PESQ), an objective
method for end-to-end speech quality assessment of narrow-band telephone networks and speech
codecs".
[32] ITU-T Recommendation Y.1541: "Network performance objectives for IP-based services".
[33] ITU-T COM12-42 (Federal Republic of Germany, January 1998): "Listening only test results for
hands-free telephones and their dependence upon room surroundings".
[34] TIA/EIA 810-A: "Telecommunications - Telephone Terminal Equipment-Transmission
Requirements for Narrowband".
[35] ITU-T Recommendation P.59: "Artificial conversational speech".
[36] ITU-T Recommendation G.711: "Pulse code modulation (PCM) of voice frequencies".
[37] ETSI TS 100 961: "Digital cellular telecommunications system (Phase 2+) (GSM); Full rate
speech; Transcoding (GSM 06.10 Release 1998)".
[38] ETSI EN 300 969: "Digital cellular telecommunications system (Phase 2+) (GSM); Half rate
speech; Half rate speech transcoding (GSM 06.20 version 8.0.1 Release 1999)".
[39] ETSI EN 300 726: "Digital cellular telecommunications system (Phase 2+) (GSM); Enhanced Full
Rate (EFR) speech transcoding (GSM 06.60 version 8.0.1 Release 1999)".
[40] ETSI EN 300 903: "Digital cellular telecommunications system (Phase 2+) (GSM); Transmission
planning aspects of the speech service in the GSM Public Land Mobile Network (PLMN) system
(GSM 03.50 version 8.1.1 Release 1999)".
[41] ISO 9614 (all parts): "Acoustics - Determination of sound power levels of noise sources using
sound intensity".
[42] Inter-Noise'96: "Evaluation of Acoustic-Quality Based on a Relative Approach", K. Genuit: 25th
Anniversary Congress Liverpool, 30.07-02.08.1996, Conference Proceedings
(Book 6 / ISBN: 1 873082 90 8), pp. 3233-3238, Liverpool, England.
[43] ITU-T Recommendation G.726: "40, 32, 24, 16 kbit/s Adaptive Differential Pulse Code
Modulation (ADPCM)".
[44] ETSI ES 202 737: "Speech and multimedia Transmission Quality (STQ); Transmission
requirements for narrowband VoIP terminals (handset and headset) from a QoS perspective as
perceived by the user".
[45] ETSI ES 202 738: "Speech and multimedia Transmission Quality (STQ); Transmission
requirements for narrowband VoIP loudspeaking and handsfree terminals from a QoS perspective
as perceived by the user".
ETSI
9 ETSI ES 201 377-2 V1.4.1 (2009-12)

[46] ETSI ES 202 739: "Speech and multimediaTransmission Quality (STQ); Transmission
requirements for wideband VoIP terminals (handset and headset) from a QoS perspective as
perceived by the user".
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] ETSI EG 201 377-1: "Speech and multimedia Transmission Quality (STQ); Specification and
measurement of speech transmission quality; Part 1: Introduction to objective comparison
measurement methods for one-way speech quality across networks".
[i.2] ETSI TR 101 110: "Digital cellular telecommunications system (Phase 2+) (GSM);
Characterisation, test methods and quality assessment for handsfree Mobile Stations (MSs)
(GSM 03.58)".
[i.3] ETSI EG 201 050: "Speech Processing, Transmission and Quality Aspects (STQ); Overall
Transmission Plan Aspects for Telephony in a Private Network".
[i.4] ETSI TBR 008: "Integrated Services Digital Network (ISDN); Telephony 3,1 kHz teleservice;
Attachment requirements for handset terminals".
[i.5] ETSI TR 102 251: "Speech Processing, Transmission and Quality Aspects (STQ); Anonymous
Test Report from 2nd Speech Quality Test Event 2002".
[i.6] 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.7] ETSI EG 202 396-3: "Speech Processing, Transmission and Quality Aspects (STQ); Speech
Quality performance in the presence of background noise Part 3: Background noise transmission -
Objective test methods".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
Acoustic Reference Level (ARL): acoustic level at MRP which results in a -10 dBm0 output at the digital interface
artificial ear: device for the calibration of earphones incorporating an acoustic coupler and a calibrated microphone for
the measurement of the sound pressure and having an overall acoustic impedance similar to that of the median adult
human ear over a given frequency band
codec: combination of an analogue-to-digital encoder and a digital-to-analogue decoder operating in opposite directions
of transmission in the same equipment
diffuse field equalization: equalization of the HATS sound pick-up, equalization of the difference, in dB, between the
spectrum level of the acoustic pressure at the ear Drum Reference Point (DRP) and the spectrum level of the acoustic
pressure at the HATS Reference Point (HRP) in a diffuse sound field with the HATS absent (see also ITU-T
Recommendation P.58 [22]) using the reverse nominal curve given in table 3 of ITU-T Recommendation P.58 [22]
ear-Drum Reference Point (DRP): point located at the end of the ear canal, corresponding to the ear-drum position
Ear Reference Point (ERP): virtual point for geometric reference located at the entrance to the listener's ear,
traditionally used for calculating telephonometric loudness ratings
ETSI
10 ETSI ES 201 377-2 V1.4.1 (2009-12)

electric power and noise levels: the following electric power and noise level units are used in the present document:
dBm0: The absolute power level at a digital reference point of the same signal that would be measured as
the absolute power level, in dBm, if the reference point was analogue. The absolute power in dBm
is defined as 10 log (power in mW/1 mW). When the impedance is 600 ohm resistive, dBm can be
referred to a voltage of 0,775 volts, which results in a reference active power of 1 mW. Note that
0 dBm0 is not the maximum digital code. For the L16-256 wideband codec adopted by
TIA TR-41, 0 dBm0 is 3,14 dB below digital full scale.
end-to-end: endpoints of a (telephone) connection between two subscribers, either between the NTPs (e.g. for bearer
services), or for speech communication between mouth and ear
G-MOS-LQOw: measure of the overall transmission quality in the presence of background noise (objective, wideband)
Head And Torso Simulator (HATS) for telephonometry: manikin extending downward from the top of the head to
the waist, designed to simulate the sound pick-up characteristics and the acoustic diffraction produced by a median
human adult and to reproduce the acoustic field generated by the human mouth
NOTE: HATS conforms to ITU-T Recommendation P.58 [22].
HATS position: correct handset position for measuring sensitivity and frequency response characteristics
NOTE: The HATS position has been shown to be essentially identical to the LRGP (loudness rating guard-ring
position) position, except for the mouth simulator direction, which has been corrected with a 19 degrees
downwards rotation to more closely match real talkers. For handsets with omnidirectional microphones,
measurements on the two heads may differ slightly, typically less than 1 dB. For handsets with directional
or noise-cancelling microphones, the differences will be larger, and the HATS position will give the more
realistic results. See ITU-T Recommendation P.64 [24] (annexes D and E) and EUSIPCO 1998,
Proceedings, Vol. II. [2].
Hands-Free Reference Point (HFRP): point located on the axis of the artificial mouth, at 50 cm from the outer plane
of the lip ring, where the level calibration is made under free-field conditions
HATS Hands-Free Reference Point (HATS-HFRP): corresponds to a reference point "n" from ITU-T
Recommendation P.58 [22]: "n" shall be one of the points numbered from 11 to 17 and defined in table 6a/P.58
(coordinates of far field front point).
NOTE: The HATS HFRP depends on the location(s) of the microphones of the terminal under test: the
appropriate axis lip-ring/HATS HFRP is as close as possible to the axis lip-ring/HFT microphone under
test. (see ITU-T Recommendation P.581 [23]).
mouth-to-ear: endpoints of a telephone connection between two subscribers between mouth and ear
Mouth Reference Point (MRP): point located on axis and 25 mm in front of the lip plane of a mouth simulator
N-MOS-LQOw: measure of the noise transmission quality in the presence of speech with background noise (objective,
wideband)
pinna simulator: device which has the approximate shape and dimensions of a median adult human pinna
reference volume control setting: receive volume control setting which results in the Receive Loudness Rating (RLR)
closest to the target value (centre of the RLR tolerance range)
NOTE: There may be separate settings for handset, headset and hands-free modes.
S-MOS-LQOw: measure of the speech transmission quality in the presence of background noise (objective, wideband)
sound pressure levels: value expressed as a ratio of the pressure of a sound to a reference pressure
NOTE 1: The following sound level units are used in the present document:
dBPa: The sound pressure level, in decibels, of a sound is 20 times the logarithm to the base 10 of the
ratio of the pressure of this sound to the reference pressure of 1 Pascal (Pa).
ETSI
11 ETSI ES 201 377-2 V1.4.1 (2009-12)

NOTE 2: 1 Pa = 1 N/m .
dBSPL: The sound pressure level, in decibels, of a sound is 20 times the logarithm to the base 10 of
-5 2
the ratio of the pressure of this sound to the reference pressure of 2 × 10 N/m (0 dBPa
corresponds to 94 dBSPL).
dB(A): The A-weighted sound level is the sound pressure level e.g. in dBSPL, weighted by use of
metering characteristics and A-weighting specified in IEC 61672 [5].
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
ARL Acoustic Reference Level
BER Bit Error Rate
BSC Base Station Controller
BTS Base Transceiver Station
C/A adjacent channel interference
C/I Carrier to Interference ratio
C/N Carrier/Noise
CSS Composite Source Signals
D D-value of terminal
dBPa decibel relative to one Pascal
dBSPL decibel Sound Pressure Level
DCME Digital Circuit Multiplication Equipment
DRP ear Drum Reference Point
DTX Discontinuous Transmission
EL Echo Loss
ERL Echo Return Loss
ERP Ear Reference Point
FER Frame Erasure Rate
GERAN GSM/EDGE Radio Access Network
G-MOS-LQOn Global mean opinion score (listening quality,objective, narrowband)
G-MOS-LQOw Global mean opinion score (listening quality,objective, wideband)
HATS Head And Torso Simulator
HFRP Hands-Free Reference Point
HFT Hands-Free Terminal
LRGP Loudness Rating Guard-ring Position
LSTR Listener SideTone Rating
LTI Linear Time Invariant
MRP Mouth Reference Point
MSC Mobile service Switching Centre
Nc circuit Noise referred to the 0 dBr-point
NLP Non-Linear Processor
N-MOS-LQOn Noise mean opinion score (listening quality,objective, narrowband)
N-MOS-LQOw Noise mean opinion score (listening quality,objective, wideband))
OLR Overall Loudness Rating
PCM Pulse Code Modulation
PESQ Perceptional Evaluation of Speech Quality
PLC Packet Loss Concealment
PLMN Public Land Mobile Network
PSTN Public Switched Telephone Network
qdu number of quantizing distortion units
RCV Residual Capital Value
RLR Receiving Loudness Rating
SLR Sending Loudness Rating
S-MOS-LQOn Speech mean opinion score (listening quality,objective, narrowband)
S-MOS-LQOw Speech mean opinion score (listening quality,objective, wideband)
SND Signal + Noise + Distortion
STMR SideTone Masking Rating
TCL Terminal Coupling Loss
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12 ETSI ES 201 377-2 V1.4.1 (2009-12)

TCLw Terminal Coupling Loss (weighted)
TELR Talker Echo Loudness Rating
TOSQA Telecommunication Objective Speech Quality Assessment
TRC TRanscoder Controller
UTRAN UMTS Terrestrial Radio Access Network
WEPL Weighted Echo Path Loss
4 General considerations for end-to-end speech quality
evaluations
When evaluation the overall speech transmission quality, networks and terminals may influence quite significantly the
speech quality of a connection: Coding, delay and processing techniques like speech echo cancellers packetizing or
DCME are mainly introduced by the network(s) but similar signal processing can be found in terminals as well. The
transfer functions and loudness ratings of a connection are mainly determined by the terminals, the background noise
and the background noise transmission are highly influenced by the terminal and the acoustical environment the
terminal is exposed to. The conversational properties which are the most important ones in a conversation are
determined by the terminal in combination with the network: double talk capability, switching characteristics, echo and
delay are dominant impairments often introduced.
In order to find the determining factors a set of subjective test procedures have been developed allowing to extract the
dominant quality aspects: Conversational test, talking and listening tests, double talk tests and listening only tests (as
described in Speech Communication 20 (pp. 241 to 254) [3] and ITU-T Recommendations P.800 [26], P.810 [27],
P.830 [28], P.831 [29] and P.832 [30]) are the basis of the parameter extraction procedure.
An overview of the methodologies is given in figures 1a to 1c.
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13 ETSI ES 201 377-2 V1.4.1 (2009-12)

Test Auditory
Performance
environment tests
parameters
Realistic Conditions
End-to-end speech
"Human Factor"
transmission quality
Conversational tests
2 subjects involved
(one at the near end of
the telephone connection,
Difficulty in
the other at the far end)
communicating
Sound quality
Double talk Annoyance caused by
echoes and switching
tests
2 subjects involved
(one at the near end of
the telephone connection,
the other at the far end) Double talk
performance
or
Talking and listening
Method of background
tests
noise transmission
1 artificial head used
(at the near end of the
telephone connection),
1 subject involved
Speech level variations
(at the far end), acting as vs. time
listener and talker
Comparison of individual
parameters under defined
conditions
Listening-only
Classification of
tests
disturbances
2 artificial heads used
(one at the near end of
the telephone connection,
Measurement conditions
the other at the far end)
(exactly defined and
Database for
1 subject as "observer"
identical for each tests
further tests
and reproducible)
T1212320-00
NOTE: The assignment of "near end" and "far end" is chosen according to the E-model (ITU-T Recommendation
G.107 [7]).
Figure 1a: Overview of test methods used for subjective evaluation - direct parameter access
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14 ETSI ES 201 377-2 V1.4.1 (2009-12)

Test Auditory
Performance
environment tests
parameters
Realistic Conditions
End-to-end speech
"Human Factor"
transmission quality
Conversational tests
2 subjects involved
(one at the near end of
the telephone connection,
Difficulty in
the other at the far end)
communicating
Sound quality
Double talk Annoyance caused by
echoes and switching
tests
2 subjects involved
(one at the near end of
the telephone connection,
the other at the far end) Double talk
performance
or
Talking and listening
Method of background
tests
noise transmission
1 artificial head used
(at the near end of the
telephone connection),
1 subject involved
Speech level variations
(at the far end), acting as vs. time
listener and talker
Comparison of individual
parameters under defined
conditions
Listening-only
Classification of
tests
disturbances
2 artificial heads used
(one at the near end of
the telephone connection,
Measurement conditions
the other at the far end)
(exactly defined and
Database for
1 subject as "observer"
identical for each tests
further tests
and reproducible)
T1212330-00
NOTE: The assignment of "near end" and "far end" is chosen according to the E-model (ITU-T Recommendation
G.107 [7]).
Figure 1b: Overview about test methods used for subjective evaluation-
parameter access via interviews
ETSI
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Increasing comparability, more analytic

15 ETSI ES 201 377-2 V1.4.1 (2009-12)

Test Auditory
Performance
environment tests
parameters
Realistic Conditions
End-to-end speech
"Human Factor"
transmission quality
Conversational tests
2 subjects involved
(one at the near end of
the telephone connection,
Difficulty in
the other at the far end)
communicating
Sound quality
Double talk Annoyance caused by
echoes and switching
tests
2 subjects involved
(one at the near end of
the telephone connection,
the other at the far end) Double talk
performance
or
Talking and listening
Method of background
tests
noise transmission
1 artificial head used
(at the near end of the
telephone connection),
1 subject involved Speech level variations
(at the far end), acting as vs. time
listener and talker
Comparison of individual
parameters under defined
conditions
Listening-only
Classification of
tests
disturbances
2 artificial heads used
(one at the near end of
the telephone connection,
Measurement conditions
the other at the far end)
(exactly defined and
Database for
1 subject as "observer"
identical for each tests
further tests
and reproducible)
T1212340-00
NOTE: The assignment of "near end" and "far end" is chosen according to the E-model (ITU-T
Recommendation G.107 [7]).
Figure 1c: Overview about test methods used for subjective evaluation -
parameter access by including reference conditions
The subjectively relevant parameters determining the "speech transmission quality" are as follows.
The overall quality is determined by:
• Delay and echo.
• Sound quality.
• Quality of background noise transmission at idle, in single talk and double talk conditions.
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16 ETSI ES 201 377-2 V1.4.1 (2009-12)

• Speech level variations during single talk and double talk.
• Disturbances caused by switching during single talk and double talk (completeness of speech transmission).
• Disturbances caused by echoes during single talk and double talk.
Consequently the evaluation methods need to be divided into single talk measurements and double talk evaluations. In
addition evaluations are required during periods of silence where only background noise is present.
Since the typical test setup should include all components involved in the mouth-to-ear transmission a test arrangement
should include the terminals "attached" to a realistic substitution of a user and his typical environment. Figure 2
illustrates how a test setup from end-to-end may look like typically.

Figure 2: Typical test setup for determining the speech transmission quality from end-to-end
(mouth-to-ear) by subjective evaluation of the speech quality relevant parameters
(example for handset/hands-free communication)
Test setups as shown in figure 2 are used in auditory (subjective) tests to determine the quality aspects subjectively (see
ITU-T Recommendations P.800 [26], P.810 [27], P. 830 [28], P.831 [29] and P.832 [30]). From the evaluations in
ITU-T Recommendation P.800 [26], procedures have been derived which allow the objective testing of the relevant
parameters of terminals (or even end-to-end scenarios).
5 Test configurations
This clause describes the test setups for terminals, networks and their various combinations. Since the present document
describes the general aspects of end-to-end speech quality testing, specific test setups and configuration description are
made only in general. In case any specific description of terminal or network setups is needed (e.g. buffer sizes, type of
codecs, packet loss simulations) these descriptions need to be found in the relevant standards of such transmission
systems.
5.1 Test setup for terminals
The general access to terminals is described in figure 3. The traditional way to test handset-terminals is the
LRGP-position using Type 1 artificial ear and
...