EN ISO 266:1997

SLOVENSKI STANDARD
01-avgust-1998
Akustika - Prednostne frekvence (ISO 266:1997)
Acoustics - Preferred frequencies (ISO 266:1997)
Akustik - Normfrequenzen (ISO 266:1997)
Acoustique - Fréquences normales (ISO 266:1997)
Ta slovenski standard je istoveten z: EN ISO 266:1997
ICS:
17.140.01 $NXVWLþQDPHUMHQMDLQ Acoustic measurements and
EODåHQMHKUXSDQDVSORãQR noise abatement in general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL
STANDARD
Second edition
1997-04-01
~ ~~
Acoustics - Preferred frequencies
- FrGquences nor-males
Acoustique
Reference number
IS0 266:1997(E)
IS0 266: 1997(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work of
preparing International Standards is normally carried out through IS0
technical committees. Each member body interested in a subject for which
a technical committee has been established has the right to be represented
on that committee. International organizations, governmental and non-
governmental, in liaison with ISO, also take part in the work. IS0
collaborates closely with the International Electrotechnical Commission
(IEC) on all matters of electrotechnical standardization.
Draft International Standards 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.
International Standard IS0 266 was prepared by Technical Committee
ISO/TC 43, Acoustics.
This second edition cancels and replaces the first edition (IS0 266:1975),
which has been technically revised.
Annex A of this International Standard is for information only.
0 IS0 1997
All rights reserved. Unless othewise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without permission in writing from the publisher.
International Organization for Standardization
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Internet central @ iso.ch
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Printed in Switzerland
IS0 266:1997(E)
0 IS0
Introduction
This International Standard specifies a series of preferred frequencies in
order to provide a common basis for comparing the results of acoustical
measurements.
The frequency series is referred to the reference frequency of 1 000 Hz,
which is also the reference frequency for the definition of the phon (see
IS0 31-7).
The specification of the preferred frequency series reduces to a minimum
the number of frequencies at which acoustical data need to be tabulated.
Also measurement equipment may be specifically constructed for these
frequencies.
The specified series of preferred frequencies uses powers of IO and is
therefore especially convenient for extensions into the infrasonic and
ultrasonic (frequency) ranges. Another series of frequencies that is in use is
based on the definition of the octave as the frequency ratio 1:2. The
frequencies of this series are calculated as powers of two (IEC 1260 base-
two series).
Strictly, these two series are incompatible. However the base-two series
may be accepted as a sufficient approximation to the base-ten series
because of the fact that 21i3 = 1,259 9. is very near y the same as
1O1 ’1o = 1,258 9.
Practical considerations make some additional rounding desirable: Thus
500 Hz is listed instead of 501 ,187 233. . Hz, which is the exact frequency
from the base-ten series. The calculated value of the exact frequency
expressed to five significant figures is given in the second column of
table 1. In this way, the maximum individual deviation, in the frequency
range 20 Hz to 20 000 Hz, between t
...