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.1311 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (12/2014) SERIES P: TERMINALS AND SUBJECTIVE AND OBJECTIVE ASSESSMENT METHODS Telemeeting assessment Method for determining the intelligibility of multiple concurrent t
2、alkers Recommendation ITU-T P.1311 ITU-T P-SERIES RECOMMENDATIONS TERMINALS AND SUBJECTIVE AND OBJECTIVE ASSESSMENT METHODS Vocabulary and effects of transmission parameters on customer opinion of transmission quality Series P.10 Voice terminal characteristics Series P.30 P.300 Reference systems Ser
3、ies 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 objective and subjective assessment of speech quality Series P.80 P.800 Audiovisual quality in multimedia services Series P.9
4、00 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 media Series P.1200 Telemeeting assessment Series P.1300 Statistical analysis, evaluation and reporting guidelines of quality
5、 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 the list of ITU-T Recommendations. Rec. ITU-T P.1311 (12/2014) i Recommendation ITU-T P.1311 Method for determining the inte
6、lligibility of multiple concurrent talkers Summary Recommendation ITU-T P.1311 describes a method for conducting a listening test that measures the intelligibility of multiple concurrent talkers in a teleconference. This Recommendation specifies how to conduct such a test, giving detail on stimulus
7、design, creation of source material, selection of test conditions, calibration, selection and training of listeners, test administration, and reporting of results. This Recommendation includes an electronic attachment containing American English source material referenced in Appendix I. History Edit
8、ion Recommendation Approval Study Group Unique ID* 1.0 ITU-T P.1311 2014-12-22 12 11.1002/1000/12326 Keywords Concurrent speech, coordinate response measure, CRM, spatial release from masking, speech intelligibility. _ * To access the Recommendation, type the URL http:/handle.itu.int/ in the address
9、 field of your web browser, followed by the Recommendations unique ID. For example, http:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T P.1311 (12/2014) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, informa
10、tion and communication technologies (ICTs). The ITU Telecommunication 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 world
11、wide basis. The World Telecommunication Standardization Assembly (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 WT
12、SA Resolution 1. In some areas of information technology which fall 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 adminis
13、tration and a recognized operating agency. Compliance with this 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 provis
14、ions are met. The words “shall“ or some other obligatory language 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
15、the possibility that the practice or implementation of this Recommendation 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
16、 of the Recommendation development process. As of the date of approval 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 lates
17、t information and are therefore strongly urged to consult the TSB 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.1311 (12/2014) iii Table
18、of Contents Page 1 Scope . 1 2 References . 2 3 Definitions 2 3.1 Terms defined elsewhere 2 3.2 Terms defined in this Recommendation . 2 4 Abbreviations and acronyms 3 5 Conventions 3 6 Background . 3 7 Test methodology . 3 7.1 Overview 3 7.2 Test conditions 4 7.3 Test stimuli . 6 7.4 Test environme
19、nt 7 7.5 Experiment design 7 7.6 Response format and collection 8 7.7 Listener selection 8 7.8 Reporting and interpretation of results . 9 Appendix I Examples of call signs, colours and numbers for English and standard Chinese . 10 Appendix II Examples of test condition assignment 11 Appendix III Li
20、stener instructions and user interface (Example) . 13 Bibliography. 15 Electronic attachment: English speech samples Rec. ITU-T P.1311 (12/2014) 1 Recommendation ITU-T P.1311 Method for determining the intelligibility of multiple concurrent talkers 1 Scope Modern immersive telemeeting systems have e
21、nabled remote meeting experiences that begin to resemble in-person meetings, with rapid turn-taking and frequent occurrences of multiple people speaking at once. The shift to these natural behaviours is possible because telemeeting systems are increasingly capable of delivering contextual cues that
22、allow interlocutors to stay oriented in a complex virtual meeting environment, much as they do in in-person meetings. Telemeeting systems also are under pressure to allow access from a variety of endpoints and environments, including mobile endpoints, desks, home offices, conference rooms and dedica
23、ted telemeeting rooms, and to interconnect users serviced by different networks. All of these endpoints and networks potentially have different capabilities to capture, carry, and reproduce the contextual cues that make engaging and interactive conferences possible. The industry is in need of a stan
24、dard method to quantify the intelligibility of multiple concurrent talkers that these systems provide and this Recommendation defines such a method. This Recommendation1 describes a method for obtaining an objective measure of how well a telemeeting system allows users to follow a conversation when
25、talk spurts of several talkers coincide. The method comprises a listening-only test that involves listeners observing several concurrent talkers, identifying one of them, and reporting what that talker said. The method is applicable to audio and audiovisual telemeeting systems with three or more use
26、rs in two or more locations. The test outcome is determined by the degree to which the system under test (SuT) preserves the independence of voices and limits perceptual interference between voices. For example, in a system that spatially virtualizes different talkers, the method is sensitive to cha
27、nges in the perceived angular separation of talkers and can be used to differentiate between alternative implementations of system components such as sound field capturing microphones or virtual spatial auditory displays. Implementing the method does not require access to internal components of the
28、system under test, so that the method of this Recommendation can be used to test both system components and deployed, live systems. Practitioners should be aware that telemeeting systems can and should be evaluated on several metrics. Tests conducted using the method of this Recommendation provide a
29、n objective measure of how well users follow a conversation during times of concurrent talk. This is an important aspect of meetings, but it is not the only aspect that determines the acceptance of and user satisfaction with a telemeeting system. Practitioners must evaluate which other aspects, if a
30、ny, are important for a complete evaluation of a system under test and are referred to ITU-T P.1301 and other Recommendations currently in preparation for guidance on selecting measurement procedures. Practitioners should further be aware that the method specified in this Recommendation is applicabl
31、e only to the evaluation of two or more concurrent talkers; it is not applicable to the assessment of intelligibility under conditions where only one talker is active at any one time. To evaluate the intelligibility of a single talker over a communication system practitioners are referred to b-ANSI
32、S3.2 (R2014) In particular, the method does not aim at any representativeness of the phonetic representation of a chosen language. _ 1 This Recommendation includes an electronic attachment containing speech samples. 2 Rec. ITU-T P.1311 (12/2014) 2 References The following ITU-T Recommendations and o
33、ther references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encourag
34、ed to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone docume
35、nt, the status of a Recommendation. ITU-T P.58 Recommendation ITU-T P.58 (2013), Head and torso simulator for telephonometry. ITU-T P.800 Recommendation ITU-T P.800 (1996), Methods for subjective determination of transmission quality. ITU-T P.832 Recommendation ITU-T P.832 (2000), Subjective perform
36、ance evaluation of hands-free terminals. ITU-T P.1301 Recommendation ITU-T P.1301 (2012), Subjective quality evaluation of audio and audiovisual multiparty telemeetings. 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following terms defined elsewhere: 3.1.1 double talk ITU-T
37、P.832: When near-end and far-end speech occur simultaneously at a given point, typically the terminal under test. 3.1.2 diffuse field frequency response of HATS (sound pick-up) ITU-T P.58: Difference, in dB, between the third-octave spectrum level of the acoustic pressure at the ear-drum reference p
38、oint (DRP) and the third-octave spectrum level of the acoustic pressure at the HATS reference point (HRP) in a diffuse sound field with the HATS absent. 3.2 Terms defined in this Recommendation This Recommendation defines the following terms: 3.2.1 concurrent talk: When far-end speech of two or more
39、 talkers occurs simultaneously at a given point, typically the near end terminal. 3.2.2 seat: An input to a conferencing system associated with a user. A seat is characterized by the signal path from the mouth reference point (MRP) of the talker in the seat to the listener. 3.2.3 talker: A unique in
40、dividual whose utterances are used in a listening test. 3.2.4 call sign: A two-syllable word or phrase used to address a listener. 3.2.5 target: The talker who utters the call sign the listener is listening for and the colour and number combination the listener is expected to report. May also refer
41、to the seat the talker is in. 3.2.6 interferer: Any talker that is not the target. May also refer to the seats these talkers are in. 3.2.7 condition: A unique instantiation of a conferencing system, including the system under test, the seats, and environmental factors but excluding talkers and liste
42、ners. 3.2.8 trial: The smallest unit of the test, including stimulus presentation, response collection, and feedback. 3.2.9 block: A sequence of trials characterized by the constancy of condition and talkers. Rec. ITU-T P.1311 (12/2014) 3 3.2.10 equivalent listening level: The level of the sum of al
43、l concurrent speech signals (talker and interferers) at the point corresponding to the centre of the listeners head (midpoint between the ears) with the listener absent. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: CRM Coordinate Response Measure HA
44、TS Head and Torso Simulator MRP Mouth Reference Point SuT System under Test 5 Conventions None. 6 Background The test method of this Recommendation derives from the observation that in lively group gatherings, where multiple people are speaking at once, listeners are able to listen to one talker whi
45、le “tuning out“ the others. Listeners are also able to monitor several concurrent talkers and direct their attention to any one of them at will. This remarkable ability is often referred to as the cocktail party effect b-Cherry. When employing the cocktail party effect, listeners use acoustic, visua
46、l, and contextual cues to disentangle concurrent voices and to follow the turn-taking in a conversation. For in-person meetings, where many such cues are available, listeners performance is very high and talker interaction is nearly effortless. However, when cues are degraded, e.g., when binaural sp
47、atial cues are removed by a monophonic transmission system, the ability to separate voices diminishes and the ease of communication experienced in in-person meetings is lost. Other examples of cue degradation are restricted bandwidth or “loudest speaker selection“ to cull talkers. This Recommendatio
48、n formalizes a test method for multi-talker scenarios to make them amenable to measurement of intelligibility. The measurement paradigm has been used extensively in the academic study of spatial release from masking and is known in the scientific literature as the coordinate response measure (CRM) (
49、see e.g., b-Bolia). 7 Test methodology 7.1 Overview This test measures how well a listener understands one of two (or more) concurrent talkers. During each in a series of trials, each of two (or more) talkers speaks a phrase of the form “Ready , go to now“. The listener is instructed to listen for a specific call sign, e.g., “Arrow“. At each trial, one talker, the target, speaks a phrase with that call sign and a randomly selected colour and number combination (e.g., “Ready Arrow, go to Blue Five now“.) whil
