4851903 0601883 T64 INTERNATIONAL ISO STANDARD 7196 First edition 1995-03-15 Acoustics Frequency-weighting characteristic for infrasound measurements Acoustique -- Pondération frequentielle pour le mesurage des infrasons Reference number 1SO7196:1995(E) CoPYRIGHT International Organization for Standardization LicensedbyInform 4851903 0601884 9T0 ISO7196:1995(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 been established has the right to be 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 Standard requires approval by at least 75 % of the member bodies casting avote International Standard isO 7196 was prepared by Technical Committee ISO/TC 43,Acoustics, Subcommittee SC 1,Noise. Annexes A and B of this International Standard are for information only. ISO 1995 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced microfilm, without permission in writing from the publisher. InternationalOrganizationforStandardization Case Postale 56 · CH-1211 Geneve 20 · Switzerland Printed in Switzerland ii CopYRIGHT International Organization for Standardization LicensedbyInformationHandlingServic 48519030601885 837 ISO ISO 7196:1995(E) Introduction Methods have already been standardized for the description and assess- ment of noise from various sources and with respect to various effects on human subjects (risk of hearing damage, annoyance reactions, loud- ness, perceived noisiness, interference with speech communication). These methods are described in outline in ISO 2204 and in detail in other Internationai Standards,includingISO 226, ISO 1996-1,ISO 1999, ISO/TR 3352 and ISO 3891. In all these cases, the bandwidth of the noise iseitherconsideredto liewithinthe conventionalaudiofrequencylimits 45 Hz to 11 200 Hz in the case of perceived noisiness of aircraft). The which the characteristics of sound level meters are fully specified (see IEC 651). in practice, some noises consist of, or contain components at, frequencies beiow 20o Hz. At present, there are no standardized methods for sound sessment with respect to human response. Although research in this field is comparatively sparse, there is evidence of infrasonic effects which are potentialy harmful or unpleasant to human subjects and some authorities may desire to extend their regulations or codes of practice governing noise to be highly desirable to standardize measurement and description methods in order to facilitate the exchange of information and to avoid proliferationofincompatibleprocedures. Many types of human response can be distinguished and, correspond- ingly, different description methods are, in principle, appropriate. The method described in this International Standard corresponds to the direct perception of infrasound. At present, this is the only human response for which there is an ample research base. Some literature on annoyance direct perception. On that precondition, levels measured according to this Internationai Standard would reflect the annoyance as well as the direct perception. The perception of infrasound, although apparently achieved through the auditory mechanism, differs in some respects from that usually under- stood by hearing. The normai threshoid of perception is considerabiy is, the dynamic range is smaller and the rate of growth of sensation with sound pressure level is much more rapid. In the frequency range 1 Hz to 20 Hz, sounds that are just perceptible to an average listener will yield weighted sound pressure lev