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.1120 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (03/2017) SERIES P: TELEPHONE TRANSMISSION QUALITY, TELEPHONE INSTALLATIONS, LOCAL LINE NETWORKS Communications involving vehicles Super-wideband and fullband hands-fre
2、e communication in motor vehicles Recommendation ITU-T P.1120 ITU-T P-SERIES RECOMMENDATIONS TELEPHONE TRANSMISSION QUALITY, TELEPHONE INSTALLATIONS, LOCAL LINE NETWORKS Vocabulary and effects of transmission parameters on customer opinion of transmission quality Series P.10 Voice terminal character
3、istics 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 objective and subjective assessment of speech quality Series P.80 Methods for o
4、bjective and subjective assessment of speech and video quality Series 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 strea
5、med media 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 speech and video Series P.1500 For further details, please re
6、fer to the list of ITU-T Recommendations. Rec. ITU-T P.1120 (03/2017) i Recommendation ITU-T P.1120 Super-wideband and fullband hands-free communication in motor vehicles Summary Recommendation ITU-T P.1120 will provide guidance to systems architects, developers, and test engineers of integrated aut
7、omotive speakerphones that operate around super-wideband (50-14,000Hz) and/or fullband (20-20,000Hz) audio bandwidths. Guidance is provided on the system level (i.e., mouth/ear-to-network reference point). Subjective (i.e., perceptual) testing for validating a design under real life condition is pro
8、vided in this Recommendation. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T P.1120 2017-03-01 12 11.1002/1000/13176 Keywords Automotive, fullband, FB, hands-free, motor vehicle, quality of service, QoS, speakerphone, speech quality, super-wideband, SWB, voice quality. * To
9、 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.1120 (03/2017) FOREWORD The International Telecommunication Union (ITU) is the
10、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 studying technical, operating and tariff questions and issuing Recom
11、mendations 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 which, in turn, produce Recommendations on these topics. The
12、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 and IEC. NOTE In this Recommendation, the expression “Adminis
13、tration“ 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 (to ensure, e.g., interoperability or applicability) and comp
14、liance 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 words does not suggest that compliance with the Recommendation
15、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 concerning the evidence, validity or applicability of claimed In
16、tellectual 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 patents, which may be required to implement this Recommendati
17、on. 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 2017 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, withou
18、t the prior written permission of ITU. Rec. ITU-T P.1120 (03/2017) 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 . 2 4 Abbreviations and acronyms 4 5 Conventions 5 6 How to use this Recommendation 6 6.1
19、Determining compliance with this Recommendation 6 6.2 Testing at different stages of the development cycle . 6 6.3 Application of this Recommendation to acoustic zoning concepts 6 7 Test arrangement 7 7.1 Test arrangement in a car . 8 8 Test signals and test signal levels . 12 9 Measurement paramete
20、rs and requirements for hands-free terminals 14 9.1 Delay . 14 9.2 Loudness ratings . 17 9.3 Loudness . 18 9.4 Sensitivity frequency responses . 18 9.5 Listening speech quality during single talk 25 9.6 Listening speech quality stability . 25 9.7 Idle channel noise . 27 9.8 Distortion in send . 29 9
21、.9 Distortion in receive . 29 9.10 Echo performance . 30 9.11 Switching characteristics 36 9.12 Double talk performance 39 9.13 Background noise transmission 46 10 Guidance on subjective testing . 50 Annex A Speech quality measurements 55 Annex B Principles of Relative Approach 56 Annex C Example fo
22、r a questionnaire for subjective testing 58 C Performance rating 58 C.1 Overview 58 C.2 Test categories and rating types . 58 C.3 Speech and background noise quality in send direction . 60 C.4 Speech quality in receive direction (in the car under test) . 66 iv Rec. ITU-T P.1120 (03/2017) Page C.5 Ec
23、ho cancellation performance 68 C.6 Hands-free system stability tests (car-to-car) . 74 Annex D Standard set of user scenarios 76 Annex E System stability with insufficient far-end echo loss 78 Annex F Microphone related sound field reproduction technique multi-point noise simulation (MPNS) method 80
24、 F.1 Loudspeaker set-up in the car . 80 F.2 Microphone set-up in the car 80 F.3 Background noise recordings and reference noise . 81 F.4 Equalization 81 F.5 Accuracy of the equalization 81 Bibliography. 83 Rec. ITU-T P.1120 (03/2017) 1 Recommendation ITU-T P.1120 Super-wideband and fullband hands-fr
25、ee communication in motor vehicles 1 Scope This Recommendation provides speech transmission performance and design guidance for automotive hands-free systems that operate around super-wideband (50-14,000Hz) and/or fullband (20-20,000Hz) audio bandwidths and in the future will support stereo telephon
26、y. This Recommendation covers: built in hands-free systems, aftermarket hands-free car kits, corded headsets, and wireless headsets, to be used in motor vehicles for communication. For testing purposes, the test set-up and the recommended environmental conditions are described. The methods, the anal
27、ysis and the performance parameters described in this Recommendation are based on test signals and test procedures, as defined in ITU-T P.501, ITU-T P.502, ITU-T P.340, ITU-T P.380, and ITU-T P.581. This Recommendation takes into account the concept of different acoustic zones targeted to different
28、user positions in the car, other than just the drivers position. Guidance is provided on the system level (i.e., mouth/ear-to-network reference point). For testing purposes, the test set-up and the recommended environmental conditions are described. Subjective (i.e., perceptual) testing for validati
29、ng a design under real life condition is provided in this Recommendation. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated w
30、ere 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 recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommen
31、dations 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 P.57 Recommendation ITU-T P.57 (2009), Artificial ears. ITU-T P.58 Recommendation ITU-T P.58 (1996), Head and torso simulator for
32、telephonometry. ITU-T P.79 Recommendation ITU-T P.79 (2007), Calculation of loudness ratings for telephone sets. ITU-T P.340 Recommendation ITU-T P.340 (2000), Transmission characteristics and speech quality parameters of hands-free terminals. ITU-T P.380 Recommendation ITU-T P.380 (2003), Electro-a
33、coustic measurements on headsets. ITU-T P.501 Recommendation ITU-T P.501 (2009), Test signals for use in telephonometry. 2 Rec. ITU-T P.1120 (03/2017) ITU-T P.502 Recommendation ITU-T P.502 (2000), Objective test methods for speech communication systems using complex test signals. ITU-T P.581 Recomm
34、endation ITU-T P.581 (2000), Use of head and torso simulator for hands-free terminal testing. ITU-T P.800 Recommendation ITU-T P.800 (1996), Methods for subjective determination of transmission quality. ITU-T P.800.1 Recommendation ITU-T P.800.1 (2006), Mean Opinion Score (MOS) terminology. ITU-T P.
35、830 Recommendation ITU-T P.830 (1996), Subjective performance assessment of telephone-band and wideband digital codecs. ITU-T P.831 Recommendation ITU-T P.831 (1998), Subjective performance evaluation of network echo cancellers. ITU-T P.835 Recommendation ITU-T P.835 (2003), Subjective test methodol
36、ogy for evaluating speech communication systems that include noise suppression algorithm. ITU-T P.840 Recommendation ITU-T P.840 (2003), Subjective listening test method for evaluating circuit multiplication equipment. ITU-T P.863 Recommendation ITU-T P.863 (2011), Perceptual objective listening qua
37、lity assessment. ITU-T P.863.1 Recommendation ITU-T P.863.1 (2013), Application guide for Recommendation ITU-T P.863. IEC 61260 IEC 61260 (1995), Electroacoustics Octave-band and fractional-octave-band filters. ISO 1999 ISO 1999:1990, Acoustics Determination of occupational noise exposure and estima
38、tion of noise-induced hearing impairment. ISO 3745 ISO 3745:2003, Acoustics Determination of sound power levels of noise sources using sound pressure Precision methods for anechoic and hemi-anechoic rooms. 3 Definitions 3.1 Terms defined elsewhere None. 3.2 Terms defined in this Recommendation This
39、Recommendation defines the following terms: 3.2.1 artificial ear: Device 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. 3.2.2 c
40、odec: Combination of an analogue-to-digital encoder and a digital-to-analogue decoder operating in opposite directions of transmission in the same equipment. 3.2.3 composite source signal (CSS): Signal composed in time by various signal elements. Rec. ITU-T P.1120 (03/2017) 3 3.2.4 diffuse-field equ
41、alization: Equalization of the head and torso simulator (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 diffus
42、e sound field with the HATS absent using the reverse nominal curve given in Table 3 of ITU-T P.58. 3.2.5 ear-drum reference point (DRP): A point located at the end of the ear canal, corresponding to the ear-drum position. 3.2.6 free-field equalization: The transfer characteristic of the artificial h
43、ead is equalized in such a way that for frontal sound incidence in anechoic conditions, the frequency response of the artificial head is flat. This equalization is specific to the HATS used. 3.2.7 free-field reference point: A point located in the free sound field, at least at 1.5 m distance from a
44、sound source radiating in free air (in case of a head and torso simulator (HATS), in the centre of the artificial head with no artificial head present). 3.2.8 fullband speech: Voice service with enhanced quality compared to pulse code modulation (PCM) b-ITU-T G.711 and allowing the transmission of a
45、 vocal frequency range of at least 50 Hz to 16 kHz. 3.2.9 hands-free reference point (HFRP): A 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. It corresponds to the measurement point 1
46、1, as defined in b-ITU-T P.51. 3.2.10 hands-free terminal: A telephone set that does not require the use of hands during the communications session; examples are headset, speakerphone and group-audio terminal. 3.2.11 head and torso simulator (HATS) for telephonometry: Manikin extending downward from
47、 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. 3.2.12 headset hands-free terminal: A device that includes telephone receiver and
48、transmitter, which is typically secured to the head or ear of the wearer. 3.2.13 inboard ear: Ear closest to the centreline of the vehicle. 3.2.14 maximum setting of the volume control: When a receive volume control is provided, the maximum setting of the volume control is chosen. NOTE The maximum v
49、olume should be carefully chosen in order to provide sufficient loudness for typical driving conditions but not to overload the audio system and introduce non-linearities in the echo path. 3.2.15 MOS-LQO (mean opinion score listening-only quality objective): The score calculated by means of an objective model which aims at predicting the quality for a listening-only test situation. Objective measurements made using the model given in ITU-T P.863 give results in terms o
