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Ref. No.: IS0 / R 140 - 1960 (E)
IS0
I NT ERN AT1 O NA L O RG A N I ZAT I O N FO R STA N DARD IZ AT I O N
IS0 RECOMMENDATION
R 140
FIELD AND LABORATORY MEASUREMENTS OF
AIRBORNE AND IMPACT SOUND TRANSMISSION
1st EDITION
January 1960
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 140, Field and Laboratory Il4easurements of’ Airborne
and Impact Sound Transmission, was drawn up by Technical Committee ISO/TC 43,
Acoustics, the Secretariat of which is held by the British Standards Institution (B.S.I.).
A tentative code for field and laboratory measurement of airborne and impact sound
transmission, resulting from informal international discussions, has been in use in several
European countries for a number of years. Proposals for standardization based on this
code were first submitted to Technical Committee ISO/TC 43 at the time of its meeting,
held in Berne, in September 1955. Following the discussion at this meeting, the Secretariat
drew up a revised draft proposal, which it circulated to the members of the Technical
Committee in 1956. As a result of comments sent in, the Secretariat set up a second revised
draft proposal. This document was submitted to the Technical Committee during its
meeting, held in Paris, in January 1957. The outcome of this was a third draft, this
being then approved, subject to certain editorial modifications, for submission to the
members of Technical Committee ISO/TC 43 for postal ballot, which led to its adoption
as a Draft IS0 Recommendation.
On 30 June 1958, this Draft IS0 Recommendation (No. 219) was distributed to
all the IS0 Member Bodies and was approved, subject to some editorial amendments,
by the following Member Bodies :
Italy Spain
Austria
Burma Japan Sweden
Denmark Netherlands Switzerland
Finland New Zealand United Kingdom
France Poland U.S.A.
Portugal U.S.S.R.
Germany
Hungary Romania
One Member Body opposed the approval of the Draft : Canada.
The Draft IS0 Recommendation was then submitted by correspondence to the IS0
Council, which decided, in January 1960, to accept it as an IS0 RECOMMENDATION.
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INTRODUCTION
Various workers in the field of research on sound insulation in buildings have for some
years used similar methods for the measurement of sound transmission, but these methods
have differed sufficiently to make direct comparisons of the results difficult if not impossible.
The purpose of this IS0 Recommendation is to define methods for the measurement of
sound transmission in buildings and for the expression of the results, both for field and
laboratory measurements in this sphere, so that data obtained by different workers may
be directly compared.
It is hoped that this IS0 Recommendation will not restrict in any way the development
of new techniques for the measurement of sound transmission in buildings. In some respects
the present methods are inadequate and these proposals will, no doubt, be revised as
improved methods come into use.
For laboratory measurements of the insulation of a partition, the specification is
confined to measurement of its sound insulation when flanking transmission is excluded
(see clause 2.4).
In buildings, the sound insulation of a wall or floor alone cannot in general be deter-
mined, since a significant transmission between adjoining rooms may take place by paths
other than directly through the intervening partition. Moreover, study may be required of
transmission between rooms having no common partition, e.g. diagonal transmission. The
significant quantity is then the difference between the space average sound pressure levels
(see clause 2.1) in the source room and the receiving room. Since this depends on the total
absorption in the receiving room, the measured values are adjusted to a reference value of
the absorption to give a normalized value, so that the results of measurements at different
places may be comparable.
In the case of sound produced by impacts, the method adopted is to specify a machine
for producing standard impacts on a floor, and the transmission is characterized by the
spectrum of the noise produced in the receiving room. For field measurements, the receiving
room may be any room in the building and not necessarily the room directly beneath the
floor being tested. Since the spectrum depends on the absorption in the receiving room, the
measured values are adjusted to a reference absorption.
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IS0 / R 140 - 1960 (E)
IS0 Recommendation R 140 January 1960
FIELD AND LABORATORY MEASUREMENTS OF
AIRBORNE AND IMPACT SOUND TRANSMISSION
1. SCOPE
This IS0 Recommendation defines methods of measuring the airborne sound insulation of walls,
and the airborne and impact sound insulation of floors, both in the field and in the laboratory,
for example in buildings with room sizes as in dwellings.
The way in which the airborne and impact sound fields are generated, the frequency range of
measurement and the characteristics of the necessary filters are described. Definitions are also
given of the quantity measured in each case, and of the method of normalizing the results to
make them comparable.
2. DEFINITIONS
For the purpose of this IS0 Recommendation, the following definitions and symbols apply:
2.1 LAverage sound pressure level (L), in a room. Ten times the common logarithm of the
ratio of the average of the mean square sound pressure to the square of the reference sound
pressure, the average being taken over the entire room with the exception of those parts
where the direct radiation of the sound source or the near field of the boundaries (walls, etc.)
is of significant influence. I
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where p1, p2. . . . . . pn = r.m.s. sound pressures at n different positions in the room, and
po = reference sound pressure.
Other types of space average of the sound pressure may be allowable, if they can be shown
to give (to within f 1 dB) the same level difference (see clause 2.2) as that given by the
average defined above.
2.2 LAverage sound pressure level dzference (level difference) (D), between a room containing
a source of sound and another room. Difference between the average sound pressure level
in the room containing the sound source and the average sound pressure level in the receiv-
ingroom. \
v
where LI = average sound pressure level in the source room, and
L2 = average sound pressure level in the receiving room.
This definition is given to cover the cases that arise in practice where a simple measurement of the level difference
without any correction for absorption is all that is required.
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ISO/ R 140 - 1MO (E)
2.3 Normalized level difference (DJ. Level difference corresponding to a reference value of the
"total absorption in the receiving room, 1
The normalized level difference is defined as follows:
D, = D + 10 log10 (A,/A) (3)
where D = measured level difference,
A = measured absorption in the receiving room, and
A, = reference absorption (see clause 3.5).
2.4 Sound reduction index * (R) or Transmission loss * of a partition. The sound reduction index
or transmission loss is defined as follows:
R = LI - Zz + 10 log10 (S/A)
(4)**
where LI = average sound pressure level in the source room,
L, = average sound pressure level in the receiving room,
S = area of the test specimen, and
A = total absorption in the receiving room.
2.5 Norrnalized impact sound level (L,) in the receiving room in a specific frequency band.
Difference between the average sound pressure level and 10 times the common logarithm
of the ratio between the reference absorption and the measured absorption of the receiv-
ing room.
The normalized impact sound level is defined as follows:
L, = L - 10 log,, (A,/A)
(5)
where L = average sound pressure level produced by the standard tapping
machine (see clause 5.1) in the receiving room,
A = measured absorption in the receiving room, and
A, = reference absorption (see clauses 5.5 and 6.1).
3. AIRBORNE SOUND TRANSMISSION: FIELD MEASUREMENTS
3.1 Generation of sound field. The airborne sound should be generated by a sound source or
sources in the source room.*** Awarble tone or white noise fromloudspeakers or white noise
from any other continuously sounding source should be used.
The sources should be placed to give as diffuse a sound field as possible.
NOTE: The spectral components should be so numerous that local differences of the measured sound pressure
level should not exceed 10 dB in either the source room or the receiving room.
* Sound reduction index: British terminology.
Transmission loss : American terminology.
** The quantity R is primarily defined as 10 log,, Pl/P2
where P, = sound power incident on the partition under test, and
P, = sound power transmitted through the partition under test.
Under the assumption of a diffuse statistical sound field, the formula(4)can be derived. But since the conditions
assumed cannot be guaranteed in all cases, the quantity R has here been defined directly by formula (4).
*** The number of loudspeakers and microphone positions to be used is not specified as these will depend on the
conditions and on the accuracy required.
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ISO/ R 140 - 1980 (E)
Frequency range of measurements. The measurements should be made at 'I3 or 'I2 octave
3.2
intervals (although under certain conditions when using white noise 1 octave intervals may
be permissible).
When 'I3 octave intervals are used, the frequencies of measurement should be:
100 125 160 200 250 320 400 500 640 800 1000
1250 1600 2000 2 500 and 3200 CIS.*
If 'Iz or 1 octave intervals are used, may be chosen
either the series beginning at 100 c/s and ending at 3 200 c/s,
or the series beginning at 125 CIS and ending at 4 O00 CIS.
3.3 If a warble tone is used, the frequency deviation should be at least f 10 per cent of the
of about 6 CIS, except that for frequencies above
mean frequency, at a modulation frequency
500 CIS a frequency deviation of f 50 c/s is sufficient.
3.4 If white noise is used, the measurements of the sound pressure level in the source room and
the receiving room should be made with pass band filters, of nominal width 'I3 or 'Iz octave,
with mid-frequencies equal to the above values or sufficiently close to them to cover the
frequency range 100 to 3 200 c/s adequately in 'I3 or '/z octave steps. The discrimination
characteristics of the filters should be so chosen, in relation to the sound spectra to be
measured, that
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