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1、Reference number ISO 3747:2000(E) ISO 2000 INTERNATIONAL STANDARD ISO 3747 Second edition 2000-07-01 Acoustics Determination of sound power levels of noise sources using sound pressure Comparison method in situ Acoustique Dtermination des niveaux de puissance acoustique mis par les sources de bruit
2、partir de la pression acoustique Mthode de comparaison in situ Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/18/2007 20:51:20 MDTNo reproduction or networking permitted without license
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6、t the address given below. ISO 2000 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 ISO at the address bel
7、ow or ISOs member body in the country of the requester. ISO copyright office Case postale 56 ? CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.ch Web www.iso.ch Printed in Switzerland ii ISO 2000 All rights reserved Copyright International Organization for Standard
8、ization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/18/2007 20:51:20 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 3747:2000(E) ISO 2000 All rights reservediii ContentsPage Foreword.iv Introduction.v 1Scope
9、1 2Normative references1 3Terms and definitions .2 4Test methodology3 4.1General3 4.2Accuracy.3 5Measurement uncertainty.3 6Instrumentation4 6.1Instrumentation system 4 6.2Calibration4 7Operating conditions of the source under test 5 8Preliminary survey.6 8.1Background noise6 8.2Characterization of
10、the source under test 6 9Positions of the reference sound source6 9.1One position.6 9.2More than one position .6 10Measurement procedure.7 10.1Selection of microphone positions7 10.2Measurements8 10.3Correction for background noise.8 10.4Evaluation of the measurement uncertainty.9 11Calculation of s
11、ound power levels.9 11.1One RSS position.9 11.2Several RSS positions.9 11.3A-weighted sound power level.9 12Information to be recorded.10 13Information to be reported11 Annex A (normative) Evaluation of?Lfand of the measurement uncertainty12 Annex B (informative) Recommendations for the location of
12、the reference sound source and the microphones, if only one RSS position is used.14 Bibliography18 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/18/2007 20:51:20 MDTNo reproduction or
13、networking permitted without license from IHS -,-,- ISO 3747:2000(E) iv ISO 2000 All rights reserved Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally
14、 carried out through ISO 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 w
15、ork. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3. Draft International Standards adopted by the technical
16、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. Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of patent righ
17、ts. ISO shall not be held responsible for identifying any or all such patent rights. International Standard ISO 3747 was prepared by Technical Committee ISO/TC 43, Acoustics, Subcommittee SC 1, Noise. This second edition cancels and replaces the first edition (ISO 3747:1987), which has been technica
18、lly revised. Annex A forms a normative part of this International Standard. Annex B is for information only. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/18/2007 20:51:20 MDTNo reprod
19、uction or networking permitted without license from IHS -,-,- ISO 3747:2000(E) ISO 2000 All rights reservedv Introduction This International Standard is one of the ISO 3740 series which, together with ISO 9614, specifies various methods for determining sound power levels of machines, equipment and s
20、ub-assemblies thereof. When selecting one of the methods of the 3740 series, it is necessary to decide which one is most appropriate for the conditions and purposes of the test. General guidelines to assist in the selection are provided in ISO 3740. Insofar as the operating and mounting conditions o
21、f the machine or equipment under test are concerned, only general principles are given in the ISO 3740 series. Reference should be made to the test code for a specific type of machine or equipment, if available, for specifications on mounting and operating conditions. Copyright International Organiz
22、ation for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/18/2007 20:51:20 MDTNo reproduction or networking permitted without license from IHS -,-,- Copyright International Organization for Standardization Provided by IHS under
23、 license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/18/2007 20:51:20 MDTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARDISO 3747:2000(E) ISO 2000 All rights reserved1 Acoustics Determination of sound power levels of noise s
24、ources using sound pressure Comparison method in situ 1Scope 1.1This International Standard specifies a method for determining the sound power levels of sound sources in situ, especially if non-movable. A comparison method is used and all measurements are carried out in octave bands. The measurement
25、 uncertainty depends on the test environment. The measurement uncertainty is evaluated by comparing with an indicator describing the spatial sound distribution. The accuracy will either be that of an engineering method or a survey method. The sound power level of the source under test is calculated
26、from the measured values of the sound pressure levels produced at specified measurement points by the source and by a reference sound source, respectively. The sound power level is calculated using the calibrated values of the reference sound source and the differences between the values obtained wi
27、th the source under test and those of the reference sound source. All calculations are carried out in octave bands, from which the A-weighted sound power level is determined. NOTEFor noise sources which can be moved, other relevant standards in the ISO 3740 series may be used. 1.2This International
28、Standard is applicable to all kinds of test environments which are to be found outside a laboratory environment, provided that the background noise level is sufficiently low and the sound pressure level at the microphone positions depends mainly on reflections from the room surfaces. NOTEISO 3744 or
29、 ISO 9614 may provide alternative methods. 1.3This International Standard is primarily applicable to sources which radiate broad-band noise. It may, however, also be used for sources which radiate narrow-band noise or discrete tones, although the measurement uncertainty might then become larger than
30、 stated herein. NOTEFor noise sources emitting stationary noise, ISO 9614 may be used as an alternative. 2Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subse
31、quent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the
32、 latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 6926, Acoustics Requirements for the performance and calibration of reference sound sources used for the determination of sound power levels. ISO 7
33、574-1, Acoustics Statistical methods for determining and verifying stated noise emission values of machinery and equipment Part 1: General considerations and definitions. IEC 60942, Electroacoustics Sound calibrators. Copyright International Organization for Standardization Provided by IHS under lic
34、ense with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/18/2007 20:51:20 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 3747:2000(E) 2 ISO 2000 All rights reserved IEC 61260:1995, Electroacoustics Octave-band and fractional-octave band filters.
35、IEC 61672-1, Electroacoustics Sound level meters Part 1: Specifications.1) 3Terms and definitions For the purposes of this International Standard, the following terms and definitions apply. 3.1 reference sound source RSS stable and steady source emitting constant broad-band noise with an adequate so
36、und power level, in conformance with and calibrated according to ISO 6926 3.2 calibration position position, well-defined relative to reflecting surfaces, in which the reference sound source has been calibrated 3.3 reference box hypothetical surface which is the smallest rectangular parallelepiped t
37、hat just encloses the source and terminates on the reflecting plane(s) 3.4 reverberant sound field that portion of the sound field in the test room over which the influence of sound received directly from the source is negligible 3.5 measurement distance dm closest distance from the reference box to
38、 a microphone position 3.6 background noise noise from all sources other than the source under test NOTEBackground noise may include contributions from airborne sound, structure-borne vibration, and electrical noise in instrumentation. 3.7 frequency range of interest for general purposes, the freque
39、ncy range of interest includes the octave bands with midband frequencies from 125 Hz to 8 000 Hz NOTE 1For special purposes, it is permissible to extend or reduce the frequency range of interest at either end, provided that the test environment, reference sound source and instrument accuracy are sat
40、isfactory for use over the extended or reduced frequency range. For sources which radiate predominantly high (or low) frequency sound, it is permissible to extend or reduce the frequency range of interest in order to optimize the test procedures. NOTE 2For determination of A-weighted sound power lev
41、els (or other frequency-weighted levels), frequency components within the range which do not contribute to the A-weighted sound power level may be disregarded. 1)To be published. (Revision of IEC 60651 and IEC 60804) Copyright International Organization for Standardization Provided by IHS under lice
42、nse with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/18/2007 20:51:20 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 3747:2000(E) ISO 2000 All rights reserved3 3.8 comparison method method in which the sound power level is calculated by compar
43、ing the measured sound pressure levels produced by the source under test in an environment with the sound pressure levels produced in the same environment by a reference sound source of known sound power output 3.9 excess of sound pressure level at a given distance ?Lf difference, in decibels, for a
44、 reference sound source with a reference calibration, at a given distance, between the spatial sound distribution curve of the room and the spatial sound distribution curve for a free field (6 dB per distance doubling) according to annex A NOTEThis term and its definition differ from that of ISO 142
45、57 which relates to an average difference over a given distancerange. 4Test methodology 4.1General The test method is a comparison method, that is the sound power output of the source under test is compared with that of a reference sound source with known sound power level. In order to obtain a good
46、 comparison, at least the following condition must be fulfilled: ?the test environment is sufficiently reverberant to cause the directivity of the source under test to have only an insignificant influence on the measured sound pressure levels. The better the above condition is fulfilled, the lower t
47、he measurement uncertainty will be. To make an objective evaluation of the measurement conditions, it is necessary to determine one indicator,?Lf, for the test environment. Further information about this indicator is given in annex A. 4.2Accuracy ?Lfwill be influenced by the selection of the referen
48、ce sound source and the microphone positions. Thus it may, in some cases, be possible to improve the measurement accuracy from that of a survey method to that of an engineering method by changing these positions; see annex A. 5Measurement uncertainty A single value of the sound power level of a sound source determined according to the procedures of this International Standard is likely to differ from the true value by an amount within the measurement uncertainty. The uncertainty in