ISO INTERNATIONAL STANDARD 24504 First edition 2014-08-01 Ergonomics Accessible design Sound pressure levels of spoken announcements for products and public address systems Ergonomie-Conception accessible-Niveaux de pression acoustique des annonces vocales pour les produits et systemes de sonorisation Reference number IS0 24504:2014(E) LSO IS02014 I without license from IHS Not for Resale IS0 24504:2014(E) COPYRIGHTPROTECTEDDOCUMENT @ IS0 2014 All rights reserved. Unless otherwise specified, 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 on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISO's 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 [email protected] Web www.iso.org Published in Switzerland @ IS0 2014 - All rights reserved No reproductic networking permited without license from IHS Not for Resale IS0 24504:2014(E) Contents Page Foreword ..iv Introduction. ..V 1 Scope. ..1 2 Normative references 3 Terms and definitions ..2 4 Symbols. ..4 5 Range of sound pressure level of spoken announcements .4 5.1 General 4 5.2 Criteria to determine the speech level. .5 5.3 Relevant factors related to speech perception .5 5.4 A-weighted sound pressure level method to determine the speech level .6 5.5 Simplified STI method to determine the minimum speech level. 7 Annex A (normative) Method for measuring the sound pressure level of spoken announcements and ambient noise 8 Annex B (informative) Effects of age-related hearing loss on word recognition ..10 Annex C (informative) Examples of measurement condition and result records ..16 AnnexD (informative) STI method to determine minimum speech level ..18 Bibliography .21 iii by IHS under se with I t license from IHS Not for Resale