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UDC 534
FOR STAN DARD I ZATl O N
I N T E RN AT I O N A L ORGAN I Z AT I O N
IS0 RECOMMENDATION
R 266
PREFERRED FREQUENCIES FOR ACOUSTICAL MEASUREMENTS
1st EDITION
Aug ust 1962
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standards
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore only
by the national standards organization of that country, being
a member of ISO.
For each individual country the only valid standard is the national standard of that country.
Printed in Switzerland
Also issued in French and Russian. Copies to be obtained through the national standards organizations
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BRIEF HISTORY
The IS0 Recommendation R 266, Preferred Frequencies for Acoustical Measurements, was
drawn up by the Technical Committee ISO/TC 43, Acoustics, the Secretariat of which is held
by the British Standards Institution (B.S.I.).
Work on this question by the Technical Committee began in 1957, and led, in 1960, to the
adoption of a Draft IS0 Recommendation.
In November 1960, this Draft IS0 Recommendation (No. 402) was circulated to all the IS0
Member Bodies for enquiry. It was approved, subject to a few modifications of an editorial
nature, by the following Member Bodies:
Australia France New Zealand
Austria Germany Sweden
Belgium Hungary Switzerland
Chile India United Kingdom
Denmark Iran U.S.A.
Finland Netherlands U.S.S.R.
No Member Body opposed the approval of the Draft.
The Draft IS0 Recommendation was then submitted by correspondence to the IS0 Council,
which decided, in August 1962, to accept it as an IS0 RECOMMENDATION.
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E
ISO/R 266-1962 (E)
IS0 Recommendation R 266 August 1962
PREFERRED FREQUENCIES FOR ACOUSTICAL MEASUREMENTS
1. PURPOSE
1.1 The variety of frequencies at present used for acoustical measurements makes comparison
of results inconvenient. Some of the difficulties arise from the use of frequencies spaced at
different intervals or of series starting from different reference frequencies. The purpose,
therefore, of this IS0 Recommendation is to refer all frequency-series to a single reference
frequency, and to select other frequencies in such a way as to afford a maximum number of
common frequencies in the various series. The resulting simplification thus reduces to a
minimum the number of frequencies at which acoustical data need to be tabulated; equip-
ment may be specifically constructed for these frequencies; even graph paper may be printed
in advance.
1.2 Because many kinds of measuring equipment are in current use, it is inevitable that certain
equipments will not conform to the present IS0 Recommendation; nor is it to be expected
that existing equipment will be immediately discarded. This IS0 Recommendation, however,
provides a guide to future design and construction of apparatus and to the selection of the
various frequencies in an orderly fashion.
1.3 The frequency of 1000 Hz (c/s) is of great importance in acoustics. For example, it is the
reference frequency to the definition of the phon.* 1000 Hz (c/s) frequency has therefore
been selected as the basic frequency for all series of preferred frequencies for acoustical
measurements.
1.4 For certain kinds of acoustical measurements, it is convenient to
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