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.1305 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (07/2016) SERIES P: TERMINALS AND SUBJECTIVE AND OBJECTIVE ASSESSMENT METHODS Telemeeting assessment Effect of delays on telemeeting quality Recommendation ITU-T P.1305
2、 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 Series P.40 Objective measuring appar
3、atus 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 Methods for objective and subjective assessment of speech and video quality Series P.800 Audi
4、ovisual 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 media Series P.1200 Telemeeting assessment Series P.1300 Statistical analysi
5、s, evaluation and reporting guidelines of quality measurements Series P.1400 Methods for objective and subjective assessment of quality of services other than speech and video Series P.1500 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T P.1305 (07/2016) i Recommen
6、dation ITU-T P.1305 Effect of delays on telemeeting quality Summary Recommendation ITU-T P.1305 has the primary purpose of describing the impact of echo-free transmission delays on telemeeting quality of experience (QoE). Delay has a major impact on the interaction performance of conference particip
7、ants, but is not always explicitly noticed by them; its impact being commonly attributed to other participants behaviour rather than being a system feature. Before discussing the impact of the delays, it is useful to first consider how people behave when conversing in an ideal environment. Since thi
8、s has been well studied in the linguistic discipline of conversation analysis (CA), a short discussion of conversations in that context and a discussion on the impact of delay from a CA perspective is included. Some analysis based on the alternative technique of conversation surface structures is al
9、so included. A secondary purpose of this Recommendation is to provide guidance on appropriate testing methods for evaluating the effect of delay in telemeetings. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T P.1305 2016-07-29 12 11.1002/1000/12974 Keywords Conversation, co
10、nversation analysis, delay, subjective test, telemeeting. * 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 example, http:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T P.1305 (07/2016) FO
11、REWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studyi
12、ng 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 (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups
13、 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 fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO
14、 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 Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions
15、 (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 language such as “must“ and the negative equivalents are used to express requirements. The use of such w
16、ords 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 Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position co
17、ncerning 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 approval of this Recommendation, ITU had not received notice of intellectual property, protected by
18、 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 TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2016 All rights reserved. No part of this
19、publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T P.1305 (07/2016) iii Table of Contents Page 1 Scope . 1 2 References . 1 3 Definitions 2 3.1 Terms defined elsewhere 2 3.2 Terms defined in this Recommendation . 3 4 Abbreviations and acro
20、nyms 3 5 Conventions 3 6 Existing Recommendations concerning the subjective quality evaluation in case of pure transmission delay 3 6.1 Audio delay 3 6.2 Video delay . 3 6.3 Synchronization between audio and video . 4 7 Conversation features . 4 7.1 Two-party and multi-party conversations 4 7.2 Two
21、analysis techniques . 4 7.3 Conversation analysis and turn-taking . 5 7.4 Conversation structure and styles . 7 7.5 Backchannels and other behaviours during conversations . 7 7.6 Conversation surface structure analysis . 7 8 The impact of delay 9 8.1 Turn-taking with delay . 9 8.2 Conversation surfa
22、ce structure and delays . 10 8.3 Multiparty and two-party conversations with delay . 11 8.4 Other side-impacts of delay 11 9 Factors influencing the impact of pure delay . 11 9.1 Audiovisual telemeetings . 11 9.2 User expectations 12 9.3 Asymmetric delay between participants and co-location . 12 9.4
23、 Interpersonal influences 12 10 Testing methods 12 10.1 General comments 12 10.2 Conversational-opinion tests 13 10.3 Group interaction tests 14 10.4 Communication system effectiveness tests 16 10.5 Micro-feature tests 16 11 Areas for further research regarding the impact of delay . 17 Annex A Sugge
24、stions for free-conversation tasks 18 iv Rec. ITU-T P.1305 (07/2016) Page A.1 Holiday task 18 A.2 Role-playing games 18 A.3 “Who am I?“ Celebrity Name-Guessing Task 18 A.4 Navigation tasks . 19 A.5 Story with missing parts . 19 A.6 Building blocks task variation . 19 A.7 Survival task variations . 2
25、0 Annex B Suggestions for delay-critical tasks . 21 B.1 Information exchange tasks 21 B.2 Random number verification task timed 21 Bibliography. 22 Rec. ITU-T P.1305 (07/2016) 1 Recommendation ITU-T P.1305 Effect of delays on telemeeting quality 1 Scope This Recommendation has the primary purpose of
26、 describing the impact of echo-free transmission delays on telemeeting quality of experience (QoE). Delay is special amongst communication impairments in that it can have a major impact on how well the users interact, but very often without them being explicitly aware of its presence. Typically user
27、s comment on its impact (e.g., “we kept on interrupting each other“) or assume a delayed response is due to the other participants taking a long time to respond. Consequently its impact is not always captured in conversational-opinion tests. Crucially the impact has been shown to be highly dependent
28、 on the task or activity being undertaken. The focus in this Recommendation is therefore on the human factor its purpose is not to define specific quantitative limits or values, discuss the sources of delay or to discuss methods of delay measurement or methods to reduce its impact. Before discussing
29、 the impact of the delays, it is useful to first consider how people behave when conversing in an ideal environment. Since this has been well studied in the linguistic discipline of conversation analysis (CA), a short discussion of conversations in that context and a discussion on the impact of dela
30、y from a CA perspective is included. Some analysis based on the alternative technique of conversation surface structures is also included. A secondary purpose of this Recommendation is to provide guidance on appropriate testing methods. A number of these have already been described in Annex D of ITU
31、-T P.1301 and will not be repeated here. However, there have been a number of new developments since that recommendation came into force and it is appropriate to expand on that knowledge. 2 References The following ITU-T Recommendations and other references contain provisions which, through referenc
32、e 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 encouraged to investigate the possibility of applying the most rec
33、ent 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 document, the status of a Recommendation. ITU-T G.114 Recommenda
34、tion ITU-T G.114 (2003), One-way transmission time. ITU-T G.131 Recommendation ITU-T G.131 (2003), Talker echo and its control. ITU-T P.800 Recommendation ITU-T P.800 (1996), Methods for subjective determination of transmission quality. ITU-T P.805 Recommendation ITU-T P.805 (2007), Subjective evalu
35、ation of conversational quality. ITU-T P.920 Recommendation ITU-T P.920 (2000), Interactive test methods for audiovisual communications. ITU-T P.1301 Recommendation ITU-T P.1301 (2012), Subjective quality evaluation of audio and audiovisual multiparty telemeetings. 2 Rec. ITU-T P.1305 (07/2016) ITU-
36、T P.1312 Recommendation ITU-T P.1312 (2016), Method for the measurement of the communication effectiveness of multiparty telemeetings using task performance. ITU-R BT.1359-1 Recommendation ITU-R BT.1359-1 (1998), Relative timing of sound and vision for broadcasting. 3 Definitions 3.1 Terms defined e
37、lsewhere This Recommendation uses the following terms defined elsewhere: 3.1.1 telemeeting ITU-T P.1301: A meeting in which participants are located at least two locations and the communication takes place via a telecommunication system. The term telemeeting is used to emphasize that a meeting is of
38、ten more flexible and interactive than a conventional business teleconference and could also be a private meeting. The telemeeting could be audio-only, audiovisual, text-based, or a mix of these modes. 3.1.2 conversational quality ITU-T P.1301: The perceived quality when two or more test participant
39、s have a conversation. 3.1.3 two-party ITU-T P.1301: Two persons. Example: Two persons are participating in a telemeeting, having a conversation, performing a test task together, etc. If not explicitly stated differently, two-party implicates that the persons are at two locations. 3.1.4 multiparty I
40、TU-T P.1301: More than two persons. Example: More than two persons are participating in a telemeeting, having a conversation, performing a test task together, etc. The term multiparty does not specify if the persons are distributed across two or more locations. If not explicitly stated differently,
41、multiparty implicates that the persons are at two or more than two locations. When further specification is necessary, additional terms will be used (see point-to-point and multi-point) or the number of locations will be explicitly stated. 3.1.5 point-to-point ITU-T P.1301: Two locations. Example: A
42、 multiparty point-to-point telemeeting means that more than two interlocutors are taking part, and the interlocutors are at exactly two locations. That means that in one location more than one interlocutors are present, as there are more than two persons. 3.1.6 multi-point ITU-T P.1301: More than tw
43、o locations. Example: A multiparty multi-point telemeeting means that more than two interlocutors are taking part, and the interlocutors are located across more than two locations. Multi-point does not specify if one or more than one interlocutor may be present at each location. In the special case
44、that only one person is present at each location, the term one-per-site will be used. 3.1.7 one-per-site ITU-T P.1301: One person per connected location. Example: In a multiparty one-per-site telemeeting more than two sites are connected with only one person present at each site. 3.1.8 conversation
45、analysis (CA) b-Sacks, 1974: The study of social interaction, in particular focusing on conversations. 3.1.9 turn construction unit (TCU) b-Sacks, 1974: A conversation analysis term describing the fundamental segment of speech in a conversation essentially a piece of speech that constitutes an entir
46、e turn. 3.1.10 transition relevance place (TRP) b-Sacks, 1974: A conversation analysis term which indicates where a turn or floor exchange can take place between speakers. Rec. ITU-T P.1305 (07/2016) 3 3.1.11 system effectiveness ITU-T P.1312: The ratio, expressed as a percentage, between the perfor
47、mance score achieved on a given system and the performance score obtained in face-to-face communication. 3.2 Terms defined in this Recommendation This Recommendation defines the following terms: 3.2.1 choral behaviour: Many people doing the same thing at the same time. 3.2.2 phatic expression: An ex
48、pression whose function is part of social interaction rather than to convey information. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: CA Conversation Analysis MOS Mean Opinion Score QoE Quality of Experience QoS Quality of Service TCU Turn Construct
49、ional Unit TRP Transition Relevance Place 5 Conventions None. 6 Existing Recommendations concerning the subjective quality evaluation in case of pure transmission delay In the following existing Recommendations on audio delay, video delay and audio-video synchronization the current understanding is outlined. These Recommendations have been developed for two-party interaction only. The multi-party case needs further study to ensure their applicability. 6.1 Audio delay Recommendation ITU-T G.114 states th
