ISO INTERNATIONAL STANDARD 9053-2 First edition 2020-09 Acoustics Determination of airflow resistance - Part 2: Alternating airflow method Acoustique-Determination de la résistance a I'ecoulement de I'air- Partie2:Méthodeavecécoulementd'airalternatif Reference number IS09053-2:2020(E) ISO @ISO 2020 IS09053-2:2020(E) COPYRIGHTPROTECTEDDOCUMENT @IS02020 All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting below or Iso's memberbody in the country ofthe requester. ISO copyright office CP 40i : Ch.de Blandonnet 8 CH-1214 Vernier, Geneva Phone: +41 22.749 01 11 Email: copyright@iso.org Website: www.iso.org Published in Switzerland ii @ IS0 2020 - All rights reserved IS0 9053-2:2020(E) Contents Page Foreword ..iv 1 Scope ..1 2 Normativereferences 3 Terms and definitions 4 Symbols 5 Principle ..5 6 Equipment .6 6.1 General .6 6.2 Device for producing the alternating airflow .6 6.3 Sound measuring device .7 6.4 Vessel and measurementcell. .7 6.5 Deviceformeasuringthestaticpressure .8 6.6 Deviceformeasuring thefrequencyof thepiston .8 7 Test specimens. ..8 7.1 Homogeneityoftestspecimen .8 7.2 Shape. .8 7.3 Dimensions. .8 7.3.1 Lateral dimensions. .8 7.3.2 Thickness. .9 7.4 Numberoftestspecimens .9 8 Test procedure ..9 9 Uncertainty ..10 10 Test report .11 AnnexA (normative)Effectiveratio of specificheatsforair ..12 AnnexB (informative)Acousticmodeloftheflow ..15 Annex C (informative) Calculation ofuncertainty ..17 AnnexD (informative)Airflowresistanceofperforatedsupport ..19 Bibliography .20 @IS0 2020 -All rights reserved ili