1、 I n t e r n a t i o n a l T e l e c o m m u n i c a t i o n U n i o n ITU-T P.340 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Amendment 1 (10/2014) SERIES P: TERMINALS AND SUBJECTIVE AND OBJECTIVE ASSESSMENT METHODS Voice terminal characteristics Transmission characteristics and speech quality
2、parameters of hands-free terminals Amendment 1: New Annex B: Objective test methods for multi-talker scenarios Recommendation ITU-T P.340 (2000) Amendment 1 ITU-T P-SERIES RECOMMENDATIONS TERMINALS AND SUBJECTIVE AND OBJECTIVE ASSESSMENT METHODS Vocabulary and effects of transmission parameters on c
3、ustomer opinion of transmission quality Series P.10 Voice terminal characteristics Series P.30 P.300 Reference systems Series P.40 Objective measuring apparatus Series P.50 P.500 Objective electro-acoustical measurements Series P.60 Measurements related to speech loudness Series P.70 Methods for obj
4、ective and subjective assessment of speech quality Series P.80 P.800 Audiovisual quality in multimedia services Series P.900 Transmission performance and QoS aspects of IP end-points Series P.1000 Communications involving vehicles Series P.1100 Models and tools for quality assessment of streamed med
5、ia Series P.1200 Telemeeting assessment Series P.1300 Statistical analysis, evaluation and reporting guidelines of quality measurements Series P.1400 Methods for objective and subjective assessment of quality of services other than voice services Series P.1500 For further details, please refer to th
6、e list of ITU-T Recommendations. Rec. ITU-T P.340 (2000)/Amd.1 (10/2014) i Recommendation ITU-T P.340 Transmission characteristics and speech quality parameters of hands-free terminals Amendment 1 New Annex B: Objective test methods for multi-talker scenarios Summary The existing Recommendation ITU-
7、T P.340 provides audio performance requirements and test methods for conference phones and hands-free terminals. These are limited to one-to-one meeting scenarios. Amendment 1 to Recommendation ITU-T P.340 introduces Annex B: Objective test methods for multi-talker scenarios. History Edition Recomme
8、ndation Approval Study Group Unique ID* 1.0 ITU-T P.34 1980-11-21 11.1002/1000/8001 2.0 ITU-T P.34 1984-10-19 11.1002/1000/5905 3.0 ITU-T P.34 1988-11-25 11.1002/1000/1726 4.0 ITU-T P.34 1993-03-12 XII 11.1002/1000/1727 5.0 ITU-T P.340 1996-08-30 12 11.1002/1000/3632 6.0 ITU-T P.340 2000-05-18 12 11
9、.1002/1000/5078 6.1 ITU-T P.340 (2000) Cor. 1 2004-03-31 12 11.1002/1000/7296 6.2 ITU-T P.340 (2000) Amd. 1 2014-10-29 12 11.1002/1000/12324 _ * To access the Recommendation, type the URL http:/handle.itu.int/ in the address field of your web browser, followed by the Recommendations unique ID. For e
10、xample, http:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T P.340 (2000)/Amd.1 (10/2014) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunic
11、ation Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly
12、 (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which f
13、all within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this
14、Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory languag
15、e such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTSITU draws attention to the possibility that the practice or implementation of this Reco
16、mmendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of ap
17、proval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TS
18、B patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2015 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T P.340 (2000)/Amd.1 (10/2014) iii Table of Contents Page 1) Scope . 1 2) Modifications to IT
19、U-T P.340 1 2.1) Clause 3 1 2.2) Annex B 1 Annex B Objective test methods for multi-talker scenarios . 1 B.1 Introduction 1 B.2 Test setup and configuration 2 B.3 Test 1: Adaptation time in talker alternation 3 B.4 Test 2: Level of completely overlapping (concurrent) talk bursts . 4 B.5 Test 3: Dyna
20、mic turn-taking - switching characteristics 5 B.6 Test 4: Concurrent talk test with voice-like AM-FM signals . 6 Rec. ITU-T P.340 (2000)/Amd.1 (10/2014) 1 Recommendation ITU-T P.340 Transmission characteristics and speech quality parameters of hands-free terminals Amendment 1 New Annex B: Objective
21、test methods for multi-talker scenarios 1) Scope This amendment adds new Annex B, Objective test methods for multi-talker scenarios, to Recommendation ITU-T P.340. 2) Modifications to ITU-T P.340 2.1) Clause 3 Add the following abbreviations to clause 3 in alphabetical order: DUT Device Under Test H
22、ATS Head And Torso Simulator 2.2) Annex B Add Annex B with the following new text after Annex A: Annex B Objective test methods for multi-talker scenarios (This annex forms an integral part of this Recommendation.) B.1 Introduction The existing standardized methods for measuring the performance of c
23、onference phones and hands-free terminals are dedicated mainly to one-to-one communications, i.e., the situation where only one person in a room is speaking, or when multiple people are speaking, turn-taking is so infrequent that the dynamics of turn-taking can be ignored. However, the primary use c
24、ase of conference phones and a frequent use case of hands-free terminals is to capture the voices of several people in a room. In a typical teleconferencing situation people may be speaking one at a time for a prolonged period, such as during a presentation, or they may be taking turns in rapid succ
25、ession, such as during a discussion. When multiple talkers in a room are having interactive, natural conversations among themselves with a high level of interactivity, i.e., with sudden turn-taking or concurrent talking, there is a chance that remote participants cannot hear all talkers (sometimes w
26、ithout noticing) and may also hear distorted speech, due to the limited room capture-capability of conference phones. This annex expands the scope to the communication situation where multiple talkers in a room interact frequently. Four performance criteria and their associated measurement technique
27、s are 2 Rec. ITU-T P.340 (2000)/Amd.1 (10/2014) defined. The first characterizes the adaptation time of the device under test (DUT) when it is presented with alternating (i.e., non-overlapping) talk bursts from different angular directions. The second quantifies how well the DUT preserves the level
28、of each of two concurrent (i.e., completely overlapping) talk bursts. The third simulates more complicated turn-taking dynamics between two talkers including switching with partial overlap of talk bursts and abrupt talker switching without overlap. This criterion evaluates how well the level of a ta
29、lker is maintained immediately after talker switching. The fourth criterion describes the concurrent talkers in the frequency domain to quantify how well the timbre of individual talkers is maintained. The test methods described in this Annex use a set of artificial signals. The use of artificial si
30、gnals such as composite source signal (CSS) may not be appropriate for some devices. The use of real speech signals is for further study. B.2 Test setup and configuration The test setup shall meet the requirements described in clause 5, ITU-T P. 341 and ITU-T P.581. The head and torso simulator (HAT
31、S) should be calibrated per ITU-T P.581, and should be positioned according to the test setup arrangements per clause 4 of ITU-T P.341, e.g., 80 cm of horizontal and 30 cm of vertical distance from the edge of the DUT to the lip ring centre of the HATS for conference phones as shown in Figure 6 of I
32、TU-T P.341. Test signal levels applied acoustically to the DUT should be calibrated following the procedures in clause 5. The receiving level of test signals, simulating the far-end communication point, should be set to 16 dBm0. If the DUT provides only multi-channel voice to its sending direction,
33、the measurement signal at the electrical reference point should be down-mixed to mono. The HATS should be arranged around the DUT with a certain angle setting throughout the tests. The angle terminology used in this Annex is depicted in Figure B.1. Using the reference zero-degree angle as the contro
34、l panel of the conference phone, the angle value increases in a clockwise direction. Because the performance of these tests may depend on the angular separation between the HATSs and the orientation of the HATSs towards the end point, the tests described in this Annex may need to be performed at mul
35、tiple orientations to completely specify the DUT. It is the responsibility of the experimenter to select the HATS angles and orientations that are appropriate for the DUT. For DUTs that appear symmetric, it is recommended to test the combinations of angles A and B given in Table B.1. Figure B.1 Diag
36、ram showing a conference phone and HATS angle configuration HATS A and B are positioned at the angle of 90 degree and -90 degree, respectively, in Figure B.1. Talker angle at zero-degree refers to the direction of the control panel. Rec. ITU-T P.340 (2000)/Amd.1 (10/2014) 3 Table B.1 Recommended HAT
37、S angle configurations No Angle A degree Angle B degree No Angle A degree Angle B degree 1 0 45 13 90 45 2 0 90 14 180 135 3 0 135 15 180 90 4 0 180 16 180 45 5 0 135 17 180 45 6 0 90 18 180 135 7 0 45 19 90 45 8 90 135 20 90 45 9 90 180 21 90 135 10 90 135 22 90 135 11 90 90 23 90 45 12 90 45 B.3 T
38、est 1: Adaptation time in talker alternation Purpose The purpose of this test is to measure the adaptation performance of the DUT to two alternating (i.e., non-overlapping) talk bursts, applied from different angles. Method A full-band CSS and its double talk version are used in this test ITU-T P.50
39、1. The sampling rate should be 44.1 kHz or 48 kHz. The level of the test signal should be 4.7 dBPa at the MRP. As shown in Figure B.2, the input signal is constructed such that a pair of two CSSs is applied to the HATS positioned at angle A (upper channel) and a pair of double talk CSSs is applied t
40、o another HATS located at angle B (lower channel) in an alternating manner. The signal shown in Figure B.2 (1.6 s duration) is repeated eight times to create the test signal. This simulates two alternating talkers sitting at different angles around the DUT. The measurement should be done at the elec
41、trical reference point. For each period of the test signal (Figure B.2), LA is calculated as the average of two RMS levels, each of which is measured over the active portion of the pair of CSSs (excluding the pause) corresponding to the angle A. Given a series of LAs over multiple periods of the mea
42、surement signal, i.e., LA(n), n = 0, 1, , 7, the target adaptation level, TALA, is defined as LA(n) with the smallest n, if both |LA(n) LA(n-1)| and |LA(n) LA(n-2)| are less than 1 dB. The adaptation period is defined as the smallest n such that | LA(n) TALA | 0.5 s) and the second voice-like signal
43、, SB, is applied to the HATS at angle B. Then both SA and SB are applied in a concurrent manner. This results in three time intervals as shown in Figure B.6: Single talk A, Single talk B and Concurrent talk. The measured signal during the Single talk A interval is processed by filter A (blue dotted
44、frequency response in Figure B.5) to select the frequency contents of SA, and the frequency response gain, Rec. ITU-T P.340 (2000)/Amd.1 (10/2014) 7 GA,single(k), is calculated for each k-th frequency band. The measured signal during the Single talk B interval is processed by filter B (red dotted fr
45、equency response in Figure B.5) to calculate the frequency response gain, GB,single(k) for each k-th frequency band. These two gains represent the frequency response of the DUT for single talk (no overlap), and are used as references when evaluating the response of the concurrent talkers case. From
46、the measured signal during the Concurrent talk interval, two different gains are estimated. The first is the concurrent gain for SA, GA,con(k), obtained through filter A for each frequency band. Similarly, the concurrent gain for SB, GB,con(k), is obtained using filter B. The measurements should be
47、repeated with different levels of test signals at angle B (6 dB, 3 dB, 3 dB and 6 dB relative to the original level at B) and different combinations of angles A and B. Guidance In an ideal, transparent system the signal components of signal A do not affect the signal components of signal B and vice
48、versa. Therefore, in such a system the concurrent gain of all the corresponding frequency bands should not deviate more than 0 dB from the single talk gain. |GDA(k)| = |GA,con(k) GA,single(k)| = 0 dB for all k = 1, 2, , 29 (B.2) where: k is the frequency band index for signal A |GDB(k)| = |GB,con(k)
49、 GB,single(k)| = 0 dB for all k = 1, 2, , 28 (B.3) where: k is the frequency band index for signal B When deviations do occur, DUTs with smaller absolute values of these differences are considered to have better timbre characteristics than DUTs with larger differences. DUTs with absolute differences less than 3 dB in all bands are considered to have excellent performance during concurrent talk. Figure B.5 Power spectral density of input signals for Test 4 (shown only up to 2 kHz, al
