ISO 3382 Acoustics - Measurement of the reverberation time of rooms with reference to other acoustical parameters (1997).pdf - Akustyka(1) - dzidzia2603

INTERNATIONAL

STANDARD

IS0

3382

Second edition

1997-06- 15

Acoustics - Measurement of the

reverberation time of rooms with reference

to other acoustical parameters

Acoustique - Mesurage de la d&e de rherbkation

des sales en

rgfbrence 2 d’autres paramhtres acoustiques

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Reference number

IS0 3382: 1997(E)

IS0 3382: 1997(E)

Contents

1 Scope ............................................*....*...............................~..........~~..~~...~........~~..~~~~.~~~~~.~.~~.~*.~~~*.~~...~“*~~~~.~~~~~.~~~~~~“.”~~

2 Normative references ..,............~.......,...........................................~.~..............*......~..~...~..~~.~~..*..~~~..~~~~.....~*.~~~~~..~.,.~,.

3 Definitions .........................................................*.....................=.“~.~~..~.~~.~**....~~..~.~..~~.~~~.~~~.~~~...~~~.~~~.~.~~~~.~~..~~~..~..~..~..~

4 Measurement conditions ......................................................~.........~...~..~.~~...~.....~.~....~~~...~~....~~*~~.~..~~......~.~~.*...~..~~..

4.1 General ..........................................*..........................................~.......~.~~~~.~...~......~~...~~~~*~~“.~.~.~.~.~.~~~.~~‘............~...~~~.

4.2 Equipment ..............................................................~.........~...............................~~.~.~.~~~.~........~~~~~.~.~..~.~.~...~.~.~..~.~~...

4.3 Measurement positions ................................................~.........~~...~..“........*...**.......*.......~.~~.~~~~*~.~.~*~~~~~~~~.~.~.~~~.~“.~~“”

5 Measurement procedures ..............................................~...................................”...........................~..~.............~....~... 6

5.1 General ...............................................................................~...~....~..~................~..*~~.~....~.~~~~..~..~~..~.~.~~~.~.~~..~~~..~*~...~~~

5.2 Interrupted noise method ..............................................................................................~.............“.~...................... 6

5.3 Integrated impulse response method ....................‘...............................*.......~..........~*~........*~.~~~..~.~.~~.................” 7

6 Evaluation of decay curves ..,......,..,...........................................~..........,...................,...,,.,,..~......,~......,...,..............

6.1 Interrupted noise method ....*.............................................................~...................~................................~............

6.2 Integrated impulse response method .................................~...............................................~....~...‘.......................

6.3 Non-linear decay curves ...............................................................~......*.......~........~...........~.”................................. 9

6.4 Lower limits for reliable results caused by filter and detector .~.......,..~.........................~...,.,,.................,........... 9

7 Spatial averaging ...........................................................................................................~.............~.~........................ 10

a Statement of results ...............................................................................~............~....~.....~............~.”..................~..... 10

8.1 Tables and curves .............................................................~.............~...‘.....~............~”.~~.~~...~~.....~.~..~‘....................

8.2 Test report ......................................................................==.......................................................*...........................

Annex A (informative) Auditorium measures derived from impulse responses ...................~~............................ 12

Annex B (informative) Binaural auditorium measures derived from impulse responses .......*m.......................... 19

Annex C (informative) Bibliography .,...,.,.........,,...........................................................~.................,..................,.....

0 IS0 1997

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microfilm, without permission in writing from the publisher.

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0 IS0

IS0 3382: 1997(E)

Foreword

IS0 (the International Organization for Standardization) is a worldwide federation of national standards bodies (IS0

member bodies). The work of preparing International Standards is normally carried out through IS0 technical

committees. Each member body interested in a subject for which a technical committee has been established has

the right to be represented on that committee. International organizations, governmental and non-governmental, in

liaison with ISO, also take part in the work. IS0 collaborates closely with the International Electrotechnical

Commission (IEC) on all matters of electrotechnical standardization.

Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.

Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.

International Standard IS0 3382 was prepared by Technical Committee ISORC 43, Acoustics, Subcommittee SC 2,

Building acoustics.

This second edition cancels and replaces the first edition (IS0 3382:1975), which has been technically revised.

Annexes A, B and C of this International Standard are for information only.

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IS0 3382:1997( E)

0 IS0

Introduction

The reverberation time of a room used to be regarded as the predominant indicator of its acoustical properties.

Whilst reverberation time continues to be regarded as a significant parameter, there is reasonable agreement that

other types of measurements such as relative sound pressure levels, early/late energy ratios, lateral energy

fractions, interaural cross correlation functions and background noise levels are needed for a more complete

evaluation of acoustical quality of rooms. This International Standard continues to specify room acoustic quality by

reverberation time alone, but introduces two other levels of complexity in room acoustics measurement.

Annex A presents measures based on squared impulse responses: a further measure of reverberation (early decay

time) and measures of relative sound levels, early/late energy fractions and lateral energy fractions in auditoria.

Within these categories there is still work to be done in determining which measures are the most suitable to

standardize on but, since they are all derivable from impulse responses, it is appropriate to introduce the impulse

response as the basis for standard measurements. Annex B introduces binaural measurements and the head and

torso simulators (dummy heads) required to make the measurements in auditoria.

Reverberation time measurements are important in the field of noise control in rooms as well as for the assessment

of rooms for speech and music; this International Standard also applies to measurements in these enclosures.

However, it does not apply to laboratory measurements in test facilities or reverberation rooms. Laboratory

measurements require other specifications of averaging single measurements at prescribed source and microphone

positions. This International Standard establishes a method for obtaining reverberation times from impulse

responses and from interrupted noise. In the annexes, the concepts and details of measurement procedures for

some of the newer measures are introduced, but these annexes do not constitute a part of the formal specifications

of this standard. The intention is to make it possible to compare reverberation time measurements with higher

certainty, and to promote the use of and consensus in measurement of the newer measures.

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INTERNATIONAL STANDARD o IS0

IS0 3382:1997( E)

Acoustics - Measurement of the reverberation time of rooms with

reference to other acoustical parameters

1 Scope

This International Standard specifies methods for the measurement of reverberation time in rooms. It is not

restricted to auditoria or concert halls; it is also applicable to rooms intended for speech and music or where noise

protection is a consideration. It describes the measurement procedure, the apparatus needed, the coverage

required, and the method of evaluating the data and presenting the test report. Furthermore, it is intended for

application of modern digital measuring techniques and for evaluation of room acoustical parameters derived from

impulse responses.

2 Normative references

The following standards contain provisions which, through reference in this text, constitute provisions of this

International Standard. At the time of publication, the editions indicated were valid. All standards are subject to

revision, and parties to agreements based on this International Standard are encouraged to investigate the

possibility of applying the most recent editions of the standards listed below. Members of IEC and IS0 maintain

registers of currently valid International Standards.

IS0 3741 :I 988, Acoustics - Determination of sound power levels of noise sources - Precision methods for broad-

band sources in reverberation room.

IS0 57252:1994, Accuracy (trueness and precision) of measurement methods and results - Pat? 2: Basic method

for the determination of repeatability and reproducibility of a standard measurement method.

IEC 268-1 :I 985, Sound system equipment - Part I: General.

IEC 651: 1979, Sound /eve/ meters.

IEC 1260: 1995, Electroacoustics - Octave-band filters and fractional-octave-band

filters.

ITU Recommendation P.58:1994, Head and torso simulator for telephonometry.

3 Definitions

For the purposes of this International Standard, the following definitions apply.

3.1 decay curve:

Decay of sound press ure level as a fu nction of time at one point of the room after the source of sound has ceased.

NOTE 1 This decay may be either measured after the actual cut-off

from the reverse-time integrated squa red impulse response of the room.

of a conti nuous sound source in the room or derived

NOTE 2 The decay irectly obtained after non-continuous excitation of a room (e.g. by recording a gunshot with a level

recorder) is not recommended for accurate evaluation of the reverberation time. This method should only be used for survey

purposes.

Method of obtaining decay curves by direct recording of the decay of sound pressure level after exciting a room with

broadband or band limited noise.

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