ISO INTERNATIONAL STANDARD 389-4 Firstedition 1994-10-01 Acoustics -- Reference zero for the calibration of audiometric equipment - Part 4: Reference levels for narrow-band masking noise Acoustique - Zéro de réference pour I'étalonnage d'équipements audiometrigues Partie 4: Niveaux de reference pour bruit de masque en bande étroite iso Reference number ISO 389-4:1994(E) Copyright Intermational Organization for Standardizatior Not for Resale ISO 389-4:1994(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 whicha technical committeehasbeenestablishedhastherighttobe represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. IsO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are avote International Standard ISO 389-4 was prepared by Technical Committee ISO/TC 43, Acoustics. This first edition of ISO 389-4 cancels and replaces ISO 8798:1987, of which it constitutes a minor revision. IsO 389 consists of the following parts, under the general title Acoustics - Reference zero for the calibration of audiometric equipment. Part 1: Reference equivalent threshold sound pressure levels for pure tones and supra-aural earphones Part 2: Reference equivalent threshold sound pressure levels for pure tones and insert earphones Part 3: Reference equivalent threshold force levels for pure tones and bone vibrators - Part 4: Reference levels for narrow-band masking noise Part 5: Reference equivalent threshold sound pressure levels for pure tones in the frequencyrange8kHz to 16kHz Part 6: Reference equivalent threshold sound pressure levels for acoustic test signals of short duration ISO1994 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced mechanical,including photocopying and microfilm,without permission in writing from the publisher. International OrganizationforStandardization Case Postale 56. CH-1211 Geneve 20· Switzerland Printed in Switzerland ii CISO ISO 389-4:1994(E) Part 7: Reference threshold of hearing under free-field and diffuse- field listening conditions Part 1 will be a re-issue of 1SO 389:1991. Annexes A and B of this part of ISO 389 are for information only. ii Copyright Intermational Organization for Standardization Nreructionneworkingemitewithuliceefrm Not for Resale