ISO INTERNATIONAL STANDARD 3741 Fourth edition 2010-10-01 Acoustics Determination of sound power levels and sound energy levels of noise sources using sound pressure Precision methods for reverberation test rooms Acoustique Détermination des niveaux de puissance et des niveaux d'energie acoustiques émis par les sources de bruit a partir de la pression acoustique Méthodes de laboratoire en salles d'essais réverbérantes Reference number ISO 3741:2010(E) @ISO 2010 by IHS under ted without license from IHS Not for Resale ISO 3741:2010(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In accepts no liability in this area. Adobe is a trademark of Adobe Systems Incorporated. Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by IsO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below COPYRIGHTPROTECTEDDOCUMENT @ISO2010 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, isO's memberbody 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 [email protected] Web www.iso.org Published in Switzerland @ Iso 2010 - All rights reserved ed without license from IHS Not for Resale ISO 3741:2010(E) Contents Page Foreword Introduction 1 Scope 2 Normative references. 3 Terms and definitions 4 Reference meteorological conditions.. 6 5 Reverberation test room . 6 Instrumentation and measurement equipment... ..10 7 Definition, location, installation, and operation of noise source under test.. .10 8 Measurements in the reverberation test room ..... 9 Determination of sound power levels and sound energy levels 19 10 Measurement uncertainty .... 27 11 Information to be recorded... 12 Test report..... Annex A (informative) Guidelines for the design of reverberation test rooms . 32 Annex B (informative) Guidelines for the design of rotating diffusing vanes ... Annex C (normative) Reverberation test room qualification procedure for the measurement of broad-band sound... ...35 Annex D (normative) Reverberation test room qualification procedure for the measurement of discrete-frequency components... 37 Annex E (informative) Extension of frequency range to frequencies below 1oo Hz. 42 Annex F (normative) Calculation of octave band sound power levels and sound energy levels, A- weighted sound power levels and A-weighted sound energy levels from one-third-octave band levels ... Annex G (informative) Guidelines on the development of information on measurement uncertainty ... .48 Bibliography... ..60 Copyright International Organization for Standardizalon ghts reserved ii se from IHS Not for Resale ISO 3741:2010(E) 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 carried out through IsO technical committees. Each member body interested in a subject for which a technical committee has beer International Standards are drafted in accordance with the rules given in the ISO/lEC Directives, Part 2 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 Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. IsO shall not be held responsible for ide