IEC 62777 Edition 1 0 201 6 02 INTERNATIONAL STANDARD Quality evaluation method for the sound field of directional loudspeaker array systems IE C 6 2 7 7 7 2 0 1 6 0 2 (e n ) ® Copyright International[.]
I E C 62 77 ® Edition 201 6-02 I N TE RN ATI ON AL S TAN D ARD Qu al i ty eval u ati on m eth od for th e s ou n d fi el d of d i recti on al l ou d s peaker array IEC 62777:201 6-02(en) s ys tem s TH I S P U B L I C ATI O N I S C O P YRI G H T P RO TE C T E D C o p yri g h t © I E C , G e n e va , S w i tze rl a n d All rights reserved Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either IEC or IEC's member National Committee in the country of the requester If you have any questions about IEC copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or your local IEC member National Committee for further information IEC Central Office 3, rue de Varembé CH-1 21 Geneva 20 Switzerland Tel.: +41 22 91 02 1 Fax: +41 22 91 03 00 info@iec.ch www.iec.ch Abou t th e I E C The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes International Standards for all electrical, electronic and related technologies Ab o u t I E C p u b l i c a ti o n s The technical content of IEC publications is kept under constant review by the IEC Please make sure that you have the latest edition, a corrigenda or an amendment might have been published I E C C atal og u e - webs tore i ec ch /catal og u e E l ectroped i a - www el ectroped i a org The stand-alone application for consulting the entire bibliographical information on IEC International Standards, Technical Specifications, Technical Reports and other documents Available for PC, Mac OS, Android Tablets and iPad The world's leading online dictionary of electronic and electrical terms containing 20 000 terms and definitions in English and French, with equivalent terms in additional languages Also known as the International Electrotechnical Vocabulary (IEV) online I E C pu bl i cati on s s earch - www i ec ch /s earch pu b I E C G l os s ary - s td i ec ch /g l os s ary The advanced search enables to find IEC publications by a variety of criteria (reference number, text, technical committee,…) It also gives information on projects, replaced and withdrawn publications 65 000 electrotechnical terminology entries in English and French extracted from the Terms and Definitions clause of IEC publications issued since 2002 Some entries have been collected from earlier publications of IEC TC 37, 77, 86 and CISPR I E C J u st P u bl i s h ed - webs tore i ec ch /j u s u bl i s h ed Stay up to date on all new IEC publications Just Published details all new publications released Available online and also once a month by email I E C C u s to m er S ervi ce C en tre - webs tore i ec ch /cs c If you wish to give us your feedback on this publication or need further assistance, please contact the Customer Service Centre: csc@iec.ch I E C 62 77 ® Edition 201 6-02 I N TE RN ATI ON AL S TAN D ARD Qu al i ty eval u ati on m eth od for th e s ou n d fi el d of d i recti on al l ou d s peaker array s ys tem s INTERNATIONAL ELECTROTECHNICAL COMMISSION ICS 33.1 60.50 ISBN 978-2-8322-31 36-4 Warn i n g ! M ake s u re th at you obtai n ed th i s pu bl i cati on from an au th ori zed d i s tri bu tor ® Registered trademark of the International Electrotechnical Commission –2– I EC 62777:201 I EC 201 CONTENTS FOREWORD I NTRODUCTI ON Scope Normative references Terms and definitions Personal acoustic zone and sound pressure level Personal acoustic zone Personal distance between listeners Personal distance between a directional loudspeaker array system and a listener 4 Average sound pressure level at a personal acoustic zone Personal acoustic zone index General PAZI-x PAZI-y PAZI-xy 5 PAZI-xyz Measurement of the sound pressure level for a personal acoustic zone General Characteristics to be specified Method of measurement 1 3.1 Directional loudspeaker array system 1 3.2 Microphone 1 3.3 Test signals 1 3.4 Sound pressure level curves 1 Test environment condition 1 4.1 Temperature 1 4.2 Humidity 1 I ndication of the characteristics to be specified 1 Annex A (informative) Example of standard specifications for a personal audio space Bibliography Figure – Personal acoustic zone Figure – Personal acoustic zone and sound pressure level Figure – Measuring points of the personal acoustic zone Table – Characteristics to be specified Table A.1 – Personal acoustic zone – Dimensioned example I EC 62777:201 I EC 201 –3– I NTERNATIONAL ELECTROTECHNI CAL COMMI SSI ON Q U AL I T Y E VAL U AT I O N M E TH O D F O R TH E S O U N D F I E L D O F D I RE C T I O N AL L O U D S P E AKE R ARRAY S YS T E M S FOREWORD ) The I nternati onal El ectrotechnical Commi ssi on (I EC) is a worl d wi d e organizati on for standard izati on comprisi ng all nati onal electrotech nical committees (I EC N ational Comm ittees) Th e object of I EC i s to promote i nternati on al co-operati on on al l q u esti ons cernin g standard izati on i n the el ectrical and el ectronic fi el ds To this end an d in ad di ti on to other acti vi ti es, I EC pu blish es I nternati onal Stan d ards, Technical Speci fi cati 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nternational Standard I EC 62777 has been prepared by subcommittee subcommittee technical area 1 : Quality for audio, video and multimedia systems, of IEC technical committee technical committee 00: Audio, video and multimedia systems and equipment The text of this standard is based on the following documents: FDI S Report on voti ng 00/2603/FDI S 00/2637/RVD Full information on the voting for the approval of this standard can be found in the report on voting indicated in the above table This publication has been drafted in accordance with the ISO/I EC Directives, Part –4– I EC 62777:201 I EC 201 The committee has decided that the contents of this publication will remain unchanged until the stability date indicated on the I EC web site under "http: //webstore iec.ch" in the data related to the specific publication At this date, the publication will be • • • • reconfirmed, withdrawn, replaced by a revised edition, or amended A bilingual version of this publication may be issued at a later date I EC 62777:201 I EC 201 –5– I NTRODUCTION Directional loudspeaker array systems provide focused sound for a person to listen alone without disturbing others This system is convenient for consumers who want to listen to sound without earphones or headphones This system would be widely used in consumer electronics, for example, smart phone or pad, TV, computer, navigator, and game machine The applicable area for the system could be fitness club, exhibition room, museum, shopping mall, and etc A simple and easy concept is needed to evaluate the performance of the directional loudspeaker array system for a consumer It will provide consumers with personalized audio space criteria in order to compare the audio sound field quality between various electronic products that have a directional loudspeaker array system I t is important to specify the quality evaluation method for the personal audio space and the concept of personal audio space This standard provides guidelines for general test methods to evaluate the quality of directional loudspeaker array systems –6– Q U AL I T Y E VAL U AT I O N I EC 62777:201 I EC 201 M E TH O D F O R TH E S O U N D F I E L D O F D I RE C T I O N AL L O U D S P E AKE R ARRAY S YS T E M S Scope This I nternational Standard applies to directional loudspeaker array systems of any kind, and to the parts of which they are composed or which are used as auxiliaries in such systems This standard deals with the determination of the performance of directional loudspeaker array systems, the comparison of these system types, and the determination of their proper practical application, by listing the characteristics which are useful for their specification I t specifies uniform measurement methods for these characteristics This standard is restricted to a description of the audio space around a person and the relevant method of measurement I t does not consider characteristics of loudspeakers, which are specified in I EC 60268-5 N o rm a t i v e re fe re n c e s The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application For dated references, only the edition cited applies For undated references, the latest edition of the referenced document (including any amendments) applies I EC 60268-1 , Sound system equipment – Part 1: General I EC 60268-2, Sound system equipment – Part 2: Explanation of general terms and calculation methods I EC 60268-5, Sound system equipment – Part 5: Loudspeakers IEC 61 672-1 , Electroacoustics – Sound level meters – Part 1: Specifications T e rm s a n d d e fi n i t i o n s For the purposes of this document, the following terms and definitions apply 3.1 p e rs o n a l a c o u s t i c z o n e P AZ acoustic space occupied by a person 3.2 p e rs o n a l d i s t a n c e distance between listeners and a directional loudspeaker array system 3.3 s o u n d p re s s u re l e ve l a t a p e rs o n a l a c o u s t i c z o n e P i j sound pressure level measured at the center of the surface j of the personal acoustic zone i I EC 62777:201 I EC 201 –7– 3.4 a ve g e s o u n d p re s s u re l e v e l a t a p e rs o n a l a c o u s t i c z o n e P i mean value of the sound pressure levels measured at the centers of the surfaces of the personal acoustic zone i 3.5 p e rs o n a l a c o u s t i c z o n e i n d e x P AZ I ratio of the average sound pressure level of the personal acoustic zone for a listener, to the total average sound pressure levels for listeners around the directional loudspeaker array system located at a specified personal distance 3.6 p e rs o n a l a c o u s t i c z o n e i n d e x - x P AZ I - x ratio of the average sound pressure level of the personal acoustic zone of a listener in front of the directional loudspeaker array system to the sum of the average sound pressure levels of listeners at the front, the front-right, and the front-left of the system 3.7 p e rs o n a l a c o u s t i c z o n e i n d e x - y P AZ I - y ratio of the average sound pressure level of the personal acoustic zone of a listener located in front of the directional loudspeaker array system to the sum of the average sound pressure levels of listeners at the front and the rear of the system 3.8 p e rs o n a l a c o u s t i c z o n e i n d e x - x y P AZ I - x y ratio of the average sound pressure level of the personal acoustic zone of a listener located in front of the directional loudspeaker array system to the sum of the average sound pressure levels of listeners at the front, the front-right, the front-left and the rear of the system 3.9 p e rs o n a l a c o u s t i c z o n e i n d e x - x yz P AZ I - x yz ratio of the average sound pressure level of the personal acoustic zone of a listener located in front of the directional loudspeaker array system to the sum of the average sound pressure levels of persons at the front, the front-right, the front-left, and the rear, and the front-upper, and the front-lower of the system 4 P e rs o n a l a c o u s t i c z o n e a n d s o u n d p re s s u re l e v e l P e rs o n a l a co u s ti c zo n e The personal acoustic zone (PAZ) is defined as an acoustic space occupied by a person as shown in Figure The dimensions of the personal acoustic zone are defined as W (width), D (depth), and H (height) Considering the standard size of a person, the dimensions of the personal acoustic zone shall be stated –8– I EC 62777:201 I EC 201 W D H IEC Fi g u re – Person al acou sti c zon e Person al d istan ce between l i sten ers The personal distance between separate listeners, x and z, shall be defined as the distance between the centres of their personal acoustic zones, see Figure Considering the standard size of a person, the dimension of the personal distance between listeners shall be stated −x +x +z PU PR PL −z PF Di recti onal l ou dspeaker array system z +y PD y x −y PB IEC Fi g u re – Person al acou sti c zon e an d sou n d pressu re l evel Person al d istan ce between a d i recti on al lou dspeaker array system an d a l i sten er The personal distance between a directional loudspeaker array system and a listener, y, shall be defined as a distance from the centre of the directional loudspeaker array system to the I EC 62777:201 I EC 201 –9– listener in front of the system, as shown in Figure The personal distance shall be specified by the target application area of the directional loudspeaker array system 4.4 Average sound pressure level at a personal acoustic zone The sound pressure level, , shall be defined as the sound pressure level measured at the center of the surface j of the personal acoustic zone i The average sound pressure level , shall be the mean value of the sound pressure levels of the personal acoustic zone, measured at the center of the surfaces of the personal acoustic zone, as shown in Figure P i j P i ∑ P i = j P = i j W D H IEC Figure – Measuring points of the personal acoustic zone The average sound pressure level of the personal acoustic zone, P , at the position of listener, as shown in Figure 2, is defined as follows: i a) b) c) d) e) f) F is the average sound pressure level of the personal acoustic zone in front of the directional loudspeaker array system; P L is the average sound pressure level of the personal acoustic zone at the front-left of the directional loudspeaker array system; P R is the average sound pressure level of the personal acoustic zone at the front-right of the directional loudspeaker array system; P B is the average sound pressure level of the personal acoustic zone at the rear of the directional loudspeaker array system; P U is the average sound pressure level of the personal acoustic zone at the front-upper of the directional loudspeaker array system; P D is the average sound pressure level of the personal acoustic zone at the front-lower of the directional loudspeaker array system P Personal acoustic zone index 5.1 General The personal acoustic zone index provides the ratio of the average sound pressure level of the personal acoustic zone of one listener, to the average sound pressure level of another listener at a specified personal distance – 10 – I EC 62777:201 I EC 201 P AZ I - x PAZI-x is defined as the ratio of the average sound pressure level of the personal acoustic zone of a listener in front of the directional loudspeaker array system to the sum of the average sound pressure levels of listeners at the front, the front-right, and the front-left of the system This index means a relative ratio of the average sound pressure level of the listener in front of the directional loudspeaker array system to those of the persons who are at the left side and right side of the listener PAZI-x = PF /( PF + PR + PL ) P AZ I - y PAZI-y is the ratio of the average sound pressure level of the personal acoustic zone of a listener located in front of the directional loudspeaker array system to the sum of the average sound pressure levels of listeners at the front and the rear of the system This index means a relative ratio of the average sound pressure level of a listener in front of the directional loudspeaker array system to that of the person who is at the rear side of the system PAZI-y = PF /( PF + PB ) P AZ I - x y PAZI-xy is the ratio of the average sound pressure level of the personal acoustic zone of a listener located in front of the directional loudspeaker array system to the sum of the average sound pressure levels of listeners at the front, the front-right, the front-left and the rear of the system This index means a relative ratio of the average sound pressure level of a listener located in front of the directional loudspeaker array system to the sum of those of the persons who are neighboring the listener in a 2-dimensional plane, as shown in Figure PAZI-xy = PF /( PF + PR + PL + PB ) 5 P AZ I - x y z PAZI-xyz is the ratio of the average sound pressure level of the personal acoustic zone of a listener located in front of the directional loudspeaker array system to the sum of the average sound pressure levels of persons at the front, the front-right, the front-left, and the rear, and the front-upper, and the front-lower sides of the system This index means a relative ratio of the average sound pressure level of a listener located in front of the directional loudspeaker array system to the sum of the average sound pressure levels of the persons who are neighboring the listener in 3-dimensional space PAZI-xyz = PF /( PF + PR + PL + PB + PU + PD ) 6 M e a s u re m e n t o f t h e s o u n d p re s s u re l e v e l fo r a p e rs o n a l a c o u s t i c z o n e G e n e l This standard shall be used in conjunction with IEC 60268-1 , I EC 60268-2, I EC 60268-5 and I EC 61 672-1 C h a c t e ri s t i c s t o b e s p e c i fi e d The sound pressure level shall be specified as a function of frequency measured under free field condition at a specified constant voltage with sinusoidal signal I EC 62777:201 6 I EC 201 – 11 – M e t h o d o f m e a s u re m e n t D i re c t i o n a l l o u d s p e a k e r a rra y s ys t e m The directional loudspeaker array system shall be brought under normal measuring conditions M i c ro p h o n e The measuring microphone shall be positioned in the position specified in 4 3 Test s i g n al s 3 G e n e l Acoustical measurements shall be made under the following measuring signal condition, and be indicated with the results 3 Si n u soi d al si g n al The sinusoidal test signal shall not exceed the rated voltage at any frequency The voltage across the input terminals of the directional loudspeaker array system under test shall be kept constant for all frequencies unless otherwise stated S o u n d p re s s u re l e ve l c u rve s G e n e l One or both of the following ways may be chosen for displaying the sound pressure level curves A family of frequency responses to be used shall be selected for some frequencies or frequency bands according to the application C u rve s a t s t a t e d fre q u e n c i e s A family of sound pressure level curves at stated frequencies shall be displayed C u rv e s a t s t a t e d fre q u e n c y b a n d s A family of sound pressure level curves at stated frequency bands shall be displayed T e s t e n vi ro n m e n t c o n d i t i o n T e m p e t u re The temperature of the test room shall be a standard room temperature (23 °C ± K) H u m i d i ty The humidity in the test room shall be a relative humidity (RH) of 30 % ~ 60 % I n d i c a t i o n o f t h e c h a c t e ri s t i c s t o b e s p e c i fi e d Data that shall be given by the manufacturer are indicated in Table by an “X” Data that the manufacturer should give are indicated by the letter “R” (recommended) A = data that shall be specified at stated frequencies; B = data that shall be specified at a stated frequency range – 12 – I EC 62777:201 I EC 201 This table shall be specified in a document available to buyers before purchase of the directional loudspeaker array system Table – Characteristics to be specified Clauses and subclauses System A B Personal acoustic zone and sou nd pressu re l evel Personal acoustic zon e R X Personal di stance between listen ers R X Personal di stance between a di recti onal l ou dspeaker array system R X X X and a li stener 4 Average sou nd pressu re l evel of the personal acou stic zon e Personal acoustic zone ind ex PAZI -x R X PAZI -y R X PAZI -xy R X 5 PAZI -xyz R X M easu rement of th e sou nd pressu re l evel for a personal acou stic zone Test envi ronment cond i tion Temperatu re R X R X H u mi dity I EC 62777:201 I EC 201 – 13 – Annex A (informative) Example of standard specifications for a personal audio space This annex provides an example of a standard specification for personal audio space which is intended to be used for measuring the quality of the sound field of a directional loudspeaker array system Table A.1 – Personal acoustic zone – Dimensioned example Descri ption Parameter Valu e cm Personal acoustic zone – covers a m ovi ng zon e of a head of an adu lt wh o is i n front of the di rectional loud speaker array system and intend s to listen to the sound from the system (see and Fi g u re ) H 40 W 40 D 40 x 60 z 60 y 40 Personal di stance between listen ers (see an d Figu re 2) Personal di stance between a di recti onal l ou dspeaker array system an d a l istener – for mobil e phones (see and Figu re 2) – 14 – I EC 62777:201 I EC 201 Bibliography I SO 3743-1 , Acoustics – Determination of sound power levels and sound energy levels of noise sources using sound pressure – Engineering methods for small movable sources in reverberant fields – Part : Comparison method for a hard-walled test room I SO 3743-2, Acoustics – Determination of sound power levels of noise sources using sound pressure – Engineering methods for small, movable sources in reverberant fields – Part 2: Methods for special reverberation test rooms _ I N TE RN ATI O N AL E LE CTRO TE CH N I CAL CO M M I S S I O N 3, ru e d e Va re m bé P O B ox CH -1 1 G e n e va S wi tze rl a n d Te l : + 41 F a x: + 22 91 02 1 22 91 03 00 i n fo @i e c ch www i e c ch