Acoustics - Measurement of sound insulation in buildings and of building elements - Part 3: Laboratory measurements of airborne sound insulation of building elements (ISO 140-3:1995)

Migrated from Progress Sheet (TC Comment) (2000-07-10): Launched in parallel vote ISO/CEN ++ DOW : 1997-06 (Package with parts 1 and 4 to 8) ++ DOW for EN ISO 140-1, -3 to -8 will be 1998-12-31 (2nd ext. - BTS1 C 16/1997)

Akustik - Messung der Schalldämmung in Gebäuden und von Bauteilen - Teil 3: Messung der Luftschalldämmung von Bauteilen in Prüfständen (ISO 140-3:1995)

Diese Internationale Norm legt ein Verfahren zur Messung der Luftschalldämmung von Bauteilen, wie z.B. von Wänden, Fussböden, Türen, Fenstern, Fassadenelementen und Fassaden, im Prüfstand fest, soweit sie nicht als kleine Bauteile zu klassifizieren sind (für die ein Messverfahren in ISO 140-10 festelegt ist). Die erhaltenen Prüfergebnisse können bei der Konstruktion von Bauteilen mit geeigneten akustischen Eigenschaften, für den Vergleich der Schalldämmung von Bauteilen und für die Klassifizierung derartiger Teile nach ihrer Schalldämmung verwendet werden.

Acoustique - Mesurage de l'isolation acoustique des immeubles et des éléments de construction - Partie 3: Mesurage en laboratoire de l'isolation aux bruits aériens des éléments de construction (ISO 140-3:1995)

Akustika - Merjenje zvočne izolirnosti v zgradbah in zvočne izolirnosti gradbenih elementov - 3. del: Laboratorijska merjenja izolirnosti gradbenih elementov pred zvokom v zraku (ISO 140-3:1995)

General Information

Status
Withdrawn
Publication Date
30-May-1995
Withdrawal Date
31-Aug-2010
Current Stage
9960 - Withdrawal effective - Withdrawal
Due Date
01-Sep-2010
Completion Date
01-Sep-2010

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SLOVENSKI STANDARD
SIST EN ISO 140-3:1997
01-april-1997

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]YRNRPY]UDNX ,62

Acoustics - Measurement of sound insulation in buildings and of building elements - Part

3: Laboratory measurements of airborne sound insulation of building elements (ISO 140-

3:1995)
Akustik - Messung der Schalldämmung in Gebäuden und von Bauteilen - Teil 3:
Messung der Luftschalldämmung von Bauteilen in Prüfständen (ISO 140-3:1995)
Acoustique - Mesurage de l'isolation acoustique des immeubles et des éléments de

construction - Partie 3: Mesurage en laboratoire de l'isolation aux bruits aériens des

éléments de construction (ISO 140-3:1995)
Ta slovenski standard je istoveten z: EN ISO 140-3:1995
ICS:
17.140.01 $NXVWLþQDPHUMHQMDLQ Acoustic measurements and
EODåHQMHKUXSDQDVSORãQR noise abatement in general
91.120.20 $NXVWLNDYVWDYEDK=YRþQD Acoustics in building. Sound
L]RODFLMD insulation
SIST EN ISO 140-3:1997 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN ISO 140-3:1997
---------------------- Page: 2 ----------------------
SIST EN ISO 140-3:1997
---------------------- Page: 3 ----------------------
SIST EN ISO 140-3:1997
---------------------- Page: 4 ----------------------
SIST EN ISO 140-3:1997
INTERNATIONAL
Is0
STANQARD
140-3
Second edition
1995-05-I 5
Acoustics - Measurement of sound
insulation in buildings and of building
elements -
Part 3:
Laboratory measurements of airborne sound
insulation of building elements
Acoustique - Mesurage de I ’isolement acoustique des immeubles et des
6kments de construction -
Par-tie 3: Mesurage en laboratoire de I ’affaiblissement des bruits akriens
par les klkments de construction
Reference number
IS0 140-3:1995(E)
---------------------- Page: 5 ----------------------
SIST EN ISO 140-3:1997
IS0 140=3:1995(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
(I EC) 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 140-3 was prepared by Technical Committee
ISOnC 43, Acoustics, Subcommittee SC 2, Building acoustics.
This second edition cancels and replaces the first edition (IS0 140-3:1978)
and its amendment IS0 140-3:1978/Amd.l :I 990.
IS0 140 consists of the following parts, under the general title
Acoustics - Measurement of sound insulation in buildings and of building
elements:
- Part 7: Requirements for laboratory test facilities with suppressed
flanking transmission
- Part 2: Determination, verification and application of precision data
- Part 3: Laboratory measurements of airborne sound insulation of
building elements
- Part 4: Field measurements of airborne sound insulation between
rooms
- Part 5: Field measurements of airborne sound insulation of facade
elements and facades
- Part 6: Laboratory measurements of impact sound insulation of
floors
0 IS0 1995

All rights reserved. Unless otherwise 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
Case Postale 56 l CH-1211 Geneve 20 l Switzerland
Printed in Switzerland
---------------------- Page: 6 ----------------------
SIST EN ISO 140-3:1997
Q IS0
IS0 140=3:1995(E)
- Part 7: Field measurements of impact sound insulation of floors
- Part 8: Laboratory measurement of the reduction of transmitted im-
pact noise by floor coverings on a solid standard floor
- Part 9: Laboratory measurement of room-to-room airborne sound
insulation of a suspended ceiling with a plenum above it
- Part 10: Laboratory measurement of airborne sound insulation of
small building elements
- Part 12: Laboratory measurement of room-to-room airborne and im-
pact sound insulation of an access floor
Annexes A, B and C form an integral part of this part of IS0 140. Annexes
D, E, F and G are for information only.
. . .
III
---------------------- Page: 7 ----------------------
SIST EN ISO 140-3:1997
This page intentionally left blank
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SIST EN ISO 140-3:1997
INTERNATIONAL STANDARD 0 IS0 IS0 140-3:1995(E)
Acoustics - Measurement of sound insulation in
buildings and of building elements -
Part 3:
Laboratory measurements of airborne sound insulation of
building elements
to revision, and parties to agreements based on this
1 Scope
part of IS0 140 are encouraged to investigate the
possibility of applying the most recent editions of the
This part of IS0 140 specifies a laboratory method of
standards indicated below. Members of IEC and IS0
measuring the airborne sound insulation of building
maintain registers of currently valid International
elements such as walls, floors, doors, windows,
Standards.
facade elements and facades, except those classified
as small building elements (for which a measuring
IS0 140-I : -*I, Acoustics - Measurement of sound
method is specified in IS0 140-I 0 ’)).
insulation in buildings and of building elements -
Part I: Requirements for laboratory test facilities with
The results obtained can be used to design building

elements with appropriate acoustic properties, to suppressed flanking transmission.

compare the sound insulation properties of building
IS0 140-2: ‘I 991, Acoustics - Measurement of sound
elements and to classify such elements according to
insulation in buildings and of building elements -
their sound insulation capabilities.
Part 2: Determination, verification and application of
The measurements are performed in laboratory test
precision data.
facilities in which transmission of sound on flanking
paths is suppressed. Results of measurements made IS0 354: 1985, Acoustics
- Measurement of sound

in accordance with this part of IS0 140 therefore shall absorption in a reverberation room.

not be applied directly in the field without accounting

for other factors affecting sound insulation, especially IS0 717-I : -3), Acoustics - Rating of sound insu-

flanking transmission and loss factor. lation in buildings and of building elements - Part I:

Airborne sound insulation.
2 Normative references
I EC 225: 1966, Octave, half-octave and third-octave
band filters intended for the analysis of sounds and
The following standards contain provisions which,
vibrations.
through reference in this text, constitute provisions
of this part of IS0 140. At the time of publication, the
IEC 651 :I 979, Sound level meters.
editions indicated were valid. All standards are subject

1) IS0 140-I 0:1991, Acoustics - Measurement of sound insulation in buildings and of building elements - Paa 70: Lab-

oratory measurement of airborne sound insulation of small building elements.
2) To be published. (Revision of IS0 140-I :I 990)
3) To be published. (Revision of IS0 717-l :I 982)
---------------------- Page: 9 ----------------------
SIST EN ISO 140-3:1997
0 IS0
IS0 140-3:1995(E)
where Li are the sound pressure levels L, to Ln at n
I EC 804: 1985, Integrating-averaging sound level me-
different positions in the room.
ters.
I EC 942: 1988, Sound calibrators.
3.2 sound reduction index: Ten times the common
logarithm of the ratio of the sound power WI which is
incident on a partition under test to the sound power
W2 transmitted through the specimen.
This quantity is denoted by R and is expressed in
decibels.
3 Definitions
R=lOIg- dB . . .
(4)
For the purposes of this part of IS0 140, the following
definitions apply.
In this part of IS0 140 the sound reduction index is
evaluated from
3.1 average sound pressure level in a room: Ten
. . .
R=L,-L,+lOlg$ dB
times the common logarithm of the ratio of the space (5)
and time average of the squared sound pressure to
where
the square of the reference sound pressure, the
space average being taken over the entire room with
is the average sound pressure level in the
the exception of those parts where the direct radiation
source room, in decibels;
of a sound source or the near field of the boundaries
(walls, etc.) is of significant influence.
is the average sound pressure level in the
receiving room, in decibels;
This quantity is denoted by L and is expressed in
decibels.
is the area of the test specimen, in square
metres, which is equal to the free test
If a contintiously moving microphone is used, L is
opening;
determined by
A is the equivalent sound absorption area in
Tm 2
the receiving room, in square metres.
+j P (w
. . .
L=lOlg m O2 dB
(1)
NOTES
1 The derivation of equation (5) from equation (4) assumes
where
that the sound fields are perfectly diffuse and that the
sound radiated into the receiving room is transmitted only
is the sound pressure, in pascals;
through the specimen.
is the reference sound pressure and is
2 The expression “sound transmission loss” (TL) is also in
use in English-speaking countries. It is equivalent to “sound
equal to 20 PPa;
reduction index ”.
is the integration time, in seconds.
3.3 apparent sound reduction index: Ten times
If fixed microphone positions are used, L is deter-
the common logarithm of the ratio of the sound
mined by
power W, which is incident on a partition under test
to the total sound power transmitted into the receiv-
P:+P;+---+P; dB
L=lOlg . . .
(2)
ing room if, in addition to the sound power W2 trans-
nPo
mitted through the specimen, the sound power W3,
transmitted by flanking elements or by other com-
pn are r.m.s. sound pressures at n dif-
where pl, p2...,
ponents, is significant.
ferent positions in the room. In practice, usually the
sound pressure levels Li are measured. In this case L
This quantity is denoted by R’ and is expressed in
is determined by
decibels.
L= 10 lg&$-)OG1 ’o dB . . .
(3) . . .
R ’=lOlg( w2Tw3) dB
(6)
i=l
---------------------- Page: 10 ----------------------
SIST EN ISO 140-3:1997
0 IS0 IS0 140=3:1995(E)
In general, the sound power transmitted into the re-
5 Test arrangement
ceiving room consists of the sum of several com-
ponents. Also in this case, under the assumption that
5.1 Rooms
there are sufficiently diffuse sound fields in the two
rooms, the apparent sound reduction index in this part
Laboratory test facilities shall comply with the re-
of IS0 140 is evaluated from
quirements of IS0 140-I.
. . .
R’ =L,-L,+lOlg+ dB
(7)
5.2 Test specimen
Thus, in the apparent sound reduction index, the
The sound transmission of a specimen can depend
sound power transmitted into the receiving room is
on the temperature and relative humidity in the test
related to the sound power which is incident on the
rooms at time of test and/or during curing or con-
test specimen as in equation (5), irrespective of the
ditioning of the test specimen. The conditions shall
actual conditions of transmission.
be reported.
5.2.1 Partitions
The size of the test partitions is determined by the
size of the test opening of the laboratory test facility,
as it is defined in IS0 140-I. These sizes are approxi-
4 Equipment
mately IO m2 for walls, and between 10 m* and
20 m* for floors, with the shorter edge length for both
The equipment shall comply with the requirements
walls and floors being not less than 2,3 m.
of clause 6.
A smaller size is permissible if the wavelength of free
The accuracy of the sound level measurement equip-
flexural waves at the lowest frequency considered is
ment shall comply with the requirements of accuracy
smaller than half the minimum dimension of the
classes 0 or 1 defined in IEC 651 and IEC 804. Diffuse
specimen. The smaller the specimen, however, the
field calibration of the measurement equipment is re-
more sensitive the results will be to edge constraint
quired unless microphones with the same diffuse
conditions and to local variations in sound fields.
field frequency response are used in both the source
Preferably install the test partition in a manner as
and the receiving room.
similar as possible to the actual construction with a
If absolute values of sound pressure levels have to
careful simulation of normal connections and sealing

be obtained, the complete measuring system includ- conditions at the perimeter and at joints within the

ing the microphone shall be adjusted before each partition. The mounting conditions shall be stated in

measurement using a sound calibrator which com-
the test report.
plies with the requirements of accuracy class 1 de-
The sound reduction index of solid walls and floors
fined in IEC 942.
depends strongly on coupling to surrounding struc-
tures. In order to describe properly the effect of the
The third-octave band filters shall comply with the re-
mounting, it is recommended to measure and to re-
quirements defined in IEC 225.
port the loss factor in these cases (see annex E).
The reverberation time measurement equipment shall
If the test specimen is installed in an aperture be-
comply with the requirements defined in IS0 354.
tween the source room and the receiving room, the
ratio of the aperture depths shall be approximately 2:l
Requirements for the sound source are given in 6.1
unless this is inconsistent with the practical use of the
and annex C.
test specimen.
NOTE 3 For pattern evaluation (type testing) and regular
If the specimen has one surface which is significantly
verification tests, recommended procedures for sound level

meters are given in OIML R58 and OIML R884). more absorbent than the other, the surface with the

4) OIML R58:1984, Sound level meters.
0 I ML R88: 1989, Integrating-averaging sound level meters.

These documents may be obtained from: Organisation internationale de mktrologie lbgale, 11, rue Turgot, 75009 Paris, France.

---------------------- Page: 11 ----------------------
SIST EN ISO 140-3:1997
0 IS0
IS0 140=3:1995(E)

higher absorption shall face the source room. Install Doors shall be inserted so that the lower edge is

diffusing elements in the source room in such cases. situated as near as possible to the level of the floor

of the test rooms to reproduce conditions in the actual
. . . .
In laboratories complying with IS0 140-1, ensure that
burjdjng.
the sound transmitted by any indirect path is negligi-
ble compared with the sound transmitted through the
For glazings, windows, doors, etc., the area S is the
test specimen. In order to verify this, the value of
area of the opening in the filler wall required to
R’ max for the laboratory facility shall be measured. This
accomodate the test specimen.
is done with a highly insulating construction inserted
in the test opening. The procedure to determine
The sound insulation of certain glazing systems or el-
MaX is given in annex A of IS0 140-I :-.
R’ ements, especially those incorporating laminated
glass, may be dependent on the room temperature
If the measured value of R’ for a test specimen is less
during the measurements. It is recommended that
than or equal to (R ’max - 15 dB), the indirectly trans-
the sound insulation measurements on such test
mitted sound may be considered negligible and the
specimens are made at 20 “C ,+ 3 “C in both rooms.
result is called R.
The test specimens should be stored for 24 h at the
test temperature. In addition, it can be advantageous
If R’ is larger than (R ’,ax - 15 dB), the contribution of
to make measurements at temperatures similar to
the flanking transmission for this special case shall be
those for which the test object is designed.
investigated. The methods mentioned in annex D
may be used. If necessary, try an improvement in
NOTES
flanking path suppression of the test facility.
4 As the sound insulation of windows, doors and small

Appropriate statements in the test report are necess- faCade elements depends on the dimensions, the sound

insulation in practice could differ considerably if a con-
ary [see I) of clause 91 if finally R’ is larger than
struction has an area other than the one tested in the lab-
15 dB). No calculated corrections shall be
(R max -
oratory.
applied with the exception of measurements on
doors, windows, glazings and facade elements (see
It is unlikely that test specimens (especially window panes)
annex B).
whose areas have a ratio of up to 21 will show differences
in sound insulation greater than 3 dB in the single-number
If the test specimen is smaller than the test opening,
quantity. With an area greater than that which has been
a preliminary test shall be carried out to ensure that
tested, a lower sound insulation will generally result. Accu-
sound power transmitted through the surrounding
rate, reliable values can be obtained only by measuring a
partition is small compared with the sound power
test object of the size of interest.
transmitted through the test specimen. This may be
5 Measurements on square specimens can yield smaller
checked by the methods described in annex D.
sound insulation than measurements on rectangular ones
with the same area.
5.2.2 Doors, windows, glazings and faqade
elements
5.2.2.2 Installation of windows
5.2.2.1 General
The installation of a window assembly shall be as near
The test specimen shall be tested in the same man-
as possible to the method which would be used in
ner as a partition (see 5.2.1). If the test specimen is
practice. When the window is mounted in the test
smaller than the test opening, a special partition of
opening, the niches on both sides of the windows
sufficiently high sound insulation shall be built into the
shall have different depths, preferably in a ratio of
test opening and the specimen shall be placed in that
about 2:1, unless this conflicts with the particular de-
partition. The sound transmitted through this partition
sign of the window. However, it is to be expected
and any other indirect path should be negligible com-
that results obtained with niche depths of different
pared with the sound transmitted through the test
ratios will differ.
specimen. If this is not the case, the test results shall
be corrected (see annex B).
The gap between the window and the test opening

If the test specimen is intended to be readily (about 10 m m to 13 mm around the window when

openable, it shall be installed for test so that it can be mounted in the test opening) should be filled with

opened and closed in the normal manner. It shall be absorbing material (for example, mineral wool) and

opened and closed at least five times immediately made airtight using an elastic sealant on both sides

before testing. or in accordance with the manufacturer ’s instructions.
---------------------- Page: 12 ----------------------
SIST EN ISO 140-3:1997
0 IS0 IS0 140=3:1995(E)

5.2.2.3 Installation of glass panes space between the pane and the locking ledge shall

be filled with putty, as described in annex A, about

The glass pane shall be installed into the test opening 5 mm thick. The beads shall cover not more than

so that the niches on both sides of the glass pane
15 mm and not less than 12 mm of the glass5).
have different depths with a ratio of 2:l. A gap of
NOTE 6 The sound insulation measured for a type of
about 10 mm shall remain between the glass and the
glazing does not necessarily represent the sound insulation
reveal of the test opening. This gap shall be filled with
of a window with that glazing. Preferably, therefore, the
putty as specified in annex A.
complete windows should be measured as well to obtain
information on sound insulation of the windows and not
To fix the test specimen, two wooden beads
only of the glazing.
(25 mm x 25 mm) shall be used (see figure I). The
Dimensions in millimetres
Compres sible seal
Resilient
(acoustic

NOTE - This example shows a double-glazed pane installed directly into the (smaller) aperture of a double filler wall (see

IS0 140-I :-, annex C for more details).
Figure 1 - Installation of a glass pane

5) This method of mounting and sealing a glass pane into the test opening is given as a practical, quick, airtight and repro-

ducible solution, although this is not the type of mounting in practice.
---------------------- Page: 13 ----------------------
SIST EN ISO 140-3:1997
0 IS0
IS0 140=3:1995(E)
6.2 Measurement of average sound pressure
6 Test procedure and evaluation
level
6.2.1 General
6.1 Generation of sound field in the source
Obtain the average sound pressure level by using a
room
single microphone moved from position to position,
or by an array of fixed microphones, or by a continu-
The sound generated in the source room shall be
ously moving microphone, or by swinging the micro-
steady and have a continuous spectrum in the fre-
phone. The sound pressure levels at the different
quency range considered. If filters are used, use those
microphone positions shall be averaged on an energy
with a bandwidth of at least one-third octave. If
basis [see equations (I) to (3)] for all sound source
broad-band noise is used, the spectrum may be
positions.
shaped to ensure an adequate signal-to-noise ratio at
high frequencies in the receiving room (white noise is
recommended). In either case, the sound spectrum in
the source room shall not have differences in level
greater than 6 dB between adjacent one-third-octave
6.2.2 Microphone positions
bands.
As a minimum, five microphone positions shall be
used in each room; these shall be distributed within
The sound power should be sufficiently high for the
the maximum permitted space throughout each room,
sound pressure level in the receiving room to be at
spaced uniformly (see annex C for guidance on the
least 15 dB higher than the background level in any
position of microphones).
frequency band. If this is not fulfilled, corrections shall
be applied as shown in 6.5.
The following separating distances are minimum val-
ues and shall be exceeded where possible:
If the sound source enclosure contains more than one
0,7 m between microphone positions;
loudspeaker operating simultaneously, the loud-

speakers shall be driven in phase or it shall be assured 07 m between any microph one position and room

in other ways that the radiation is uniform and bbu ndaries or diffus ers;
omnidirectional, as specified in C.1.3. It is permissible
I,0 m between any microphone position and the
to use multiple sound sources simultaneously, pro-
sound source;
vided that they are of the same type and are driven
at the same level by similar, but uncorrelated, signals.
I,0 m between any microphone position and the
Continuously moving loudspeakers may be used.
test specimen.
When using a single sound source, it shall be oper-
ated in at least two positions. They shall be in the
When using a moving microphone, the sweep radius
same room or the measurements shall be repeated in
shall be at least 1 m. The plane of the traverse shall
the opposite direction by changing source and receiv-
be inclined in order to cover a large proportion of the
ing room with one or more source positions in each
permitted room space and shall not lie in any plane
room. If one surface of the test object is significantly
within IO0 of a room surface. The duration of a trav-
more absorbent than the other, the measurements
erse period shall be not less than 15 s.
shall be made in one direction only (see 5.2.1).
Place the loudspeaker enclosure so as to give a sound
field as diffuse as possible and at such a distance 6.2.3 Averaging time
from the test specimen that the direct radiation upon

it is not dominant. The sound fields in the rooms de- At each individual microphone position, the averaging

pend strongly on the type and on the position of the
time shall be at least 6 s at each frequency band with
sound source. Qualification of the loudspeakers and
centre frequencies below 400 Hz. For bands of higher

of the loudspeaker positions shall be performed using centre frequencies, it is permissible to decrease the

the procedures given in annex C. Guidance for the time to not less than 4 s. Using a moving microphone,

use of continuously moving loudspeakers is given in the averaging time shall cover a whole number of

C.2.5. traverses and shall be not less than 30 s.
---------------------- Page: 14 ----------------------
SIST EN ISO 140-3:1997
0 IS0 IS0 140=3:1995(E)
Moving microphones which meet the requirements
6.3 Frequency range of measurements
of 6.2.2 may be used but the traverse time shall be
not less than 30 s.
The sound pressure level shall be measured using
one-third-octave band filters having at least the fol-
lowing centre frequencies, in hertz:
6.5 Correction for background noise
100 125 160 200 250 315
Measurements of background noise levels shall be
made to ensure that the observations in the receiving
400 500 630 800 1 000 1 250
room are not affected by extraneous sound such as
1600 2000 2500 3150 4000 5000
noise from outside the test room, electrical noise in
the receiving system, or electrical cross-talk between
If additional information in the low-frequency range is
the source and the receiving systems. To check the
required, use one-third-octave band filters with the
latter condition, replace the microphone by a dummy
following centre frequencies, in hertz:
microphone or replace the loudspeaker by an equiv-
alent impedance. The background level shall be at
63 80
least 6 dB (and preferably more than 15 dB) below the
level of signal and background noise combined.
Guidance is given in annex F for such additional
measurements in the low-frequency bands.
If the difference in levels is smaller than 15 dB but
greater than 6 dB, calculate corrections to the signal
level according to the equation
L = 10 lg(104b ”o - IO ”“‘) dB . . .
(9)
6.4 Measurement of reverberation time and
evaluation of the equivalent sound
where
absorption area
is the adjusted signal level, in decibels;
The correction term of equation (5) containing the
L is the level of signal and background noise
equivalent sound absorption area is evaluated from sb
combined, in decibels;
the reverberation time measured according to
IS0 354 and determined using Sabine ’s formula
is the background noise level, in decibels.
0,16V
A=7 . . .
(8)
If the difference in levels is less than or equal to
6 dB in any of the frequency bands, use the correction
1,3 dB corresponding to a difference of 6 dB. In that
case, R shall be given in the measurement report so
A is the equivalent sound absorption area, in
that it clearly appears that the reported R values are
square metres;
the limit of measurement [see I) of clause 91.
V is the receiving room volume, in cubic
metres;
7 Precision
T is the reverberation time in the receiving
It is required that the measurement procedure gives
room, in seconds.
satisfactory repeatability. This shall be determined in
accordance with the method shown in IS0 140-2 and
Following IS0 354, the evaluation of the reverberation
shall be verified from time to time, particularly when
time from the decay cun/e shall begin about 0,l s af-
a change is made in the procedure or instrumentation.
ter the sound source has been switched off, or from
a sound pressure level a few decibels lower than that
NOTE 7 Numerical requirements for repeatability are
at the beginning of the decay. The range used shall
given in IS0 140-2.
not be less than 20 dB, and should not be so large
that the observed decay cannot be approximated by
8 Expression of results
a straight line. The bottom of this range shall be at
least 10 dB above the background noise level.
For the statement of the airborne sound insulation of
The minimum number of decay measurements re-
the test specimen, the values of the sound reduction
quired for each frequency band is six. At least one
index shall be given at all frequencies of measure-
loudspeaker position and three microphone positions
ment, to one decimal place, in tabular form and in the
with two readings in each case shall be used.
form of a curve. Graphs in the test report shall show
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SIST EN ISO 140-3:1997
0 IS0
IS0 140-3:1995(E)
the value in decibels plotted against frequency on a e) date of test;
logarithmic scale, and the following dimensions shall
f) description of the test specimen with sectional
be used:
drawing and mounting conditions, including size,
thickness, mass per unit area, curing time and
5 mm for the one-third-octave band;
conditions of components; statement indicating
20 mm for 10 dB.
who mounted the test object (test institute or
manufacturer);
The use of a form in accordance with annex G is
preferred. Being a short version of the test r
...

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