ASTM E966-99
(Guide)Standard Guide for Field Measurements of Airborne Sound Insulation of Building Facades and Facade Elements
Standard Guide for Field Measurements of Airborne Sound Insulation of Building Facades and Facade Elements
SCOPE
1.1 This guide covers field procedures for measuring the sound level reduction or sound transmission loss of an installed building facade or facade element in specified frequency bands. These values may be used separately to predict interior levels or combined into a single number such as by Classification E 413 (with precautions) or Classification E 1332 to estimate the sound insulating properties of the test element, FOITC, in the field. The results are applicable to installations similar to that tested when exposed to an outdoor sound field similar to that used during the measurement.
1.1.1 The facade element may be the exterior wall of a room in the building, or a portion of that wall such as a door or window, when the remainder of that wall has substantially greater sound insulation than the portion under test.
1.2 To cope with the variety of outdoor test geometry that may be encountered, several testing techniques are presented. These techniques and their general applicability are summarized in Table 1 and Figs. 1-6 .
1.3 This guide may be used to determine the outdoor-indoor level reduction (OILR), which is the difference in sound pressure between a specified outdoor sound field and the resulting sound pressure level in the room abutting the test facade or facade element. The outdoor sound field and its measurement must be thoroughly described. The resulting level reduction or transmission loss value will depend on the outdoor field geometry and the point at which it is measured or represented.
1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses are provided for information only.
1.5 This standard does not purport to address the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability or regulatory limitations prior to use.
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Designation: E 966 – 99
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Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Guide for
Field Measurements of Airborne Sound Insulation of
Building Facades and Facade Elements
This standard is issued under the fixed designation E 966; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
The sound transmission of a building facade or facade element as measured under field conditions
is dependent not only on the physical characteristics of the facade, but also on the characteristics of
the incident sound field used to make the measurement. This is also true for laboratory tests of panels
using the two-room method described in Test Method E 90; however, the incident sound field in these
controlled tests is made uniformly diffuse. The same is approximately true for field measurements of
noise reduction and transmission loss by Test Method E 336. Such uniformity is not possible for
facade measurements in the field where each situation is unique, resulting in incident sound fields that
may range all the way from free field produced by a point source to quasi-diffuse produced by a line
source.
At this time, there are insufficient data available to specify a single, standard measurement
procedure suitable for all field situations. For this reason, this guide provides a number of alternative
test procedures for the measurements of facade field level reduction and transmission loss.
1. Scope measurement must be thoroughly described. The resulting
level reduction or transmission loss value will depend on the
1.1 This guide covers field procedures for measuring the
outdoor field geometry and the point at which it is measured or
sound level reduction or sound transmission loss of an installed
represented.
building facade or facade element in specified frequency
1.4 The values stated in SI units are to be regarded as
bands. These values may be used separately to predict interior
standard. The values given in parentheses are provided for
levels or combined into a single number such as by Classifi-
information only.
cation E 413 (with precautions) or Classification E 1332 to
1.5 This standard does not purport to address the safety
estimate the sound insulating properties of the test element,
concerns, if any, associated with its use. It is the responsibility
FOITC, in the field. The results are applicable to installations
of the user of this standard to establish appropriate safety and
similar to that tested when exposed to an outdoor sound field
health practices and determine the applicability of regulatory
similar to that used during the measurement.
limitations prior to use.
1.1.1 The facade element may be the exterior wall of a room
in the building, or a portion of that wall such as a door or
2. Referenced Documents
window, when the remainder of that wall has substantially
2.1 ASTM Standards:
greater sound insulation than the portion under test.
C 423 Test Method for Sound Absorption and Sound Ab-
1.2 To cope with the variety of outdoor test geometry that
sorption Coefficients by the Reverberation Room Method
may be encountered, several testing techniques are presented.
C 634 Terminology Relating To Environmental Acoustics
These techniques and their general applicability are summa-
E 90 Test Method for Laboratory Measurement of Airborne
rized in Table 1 and Figs. 1-6.
Sound Transmission Loss of Building Partitions
1.3 This guide may be used to determine the outdoor-indoor
E 336 Test Method for Measurement of Airborne Sound
level reduction (OILR), which is the difference in sound
Insulation in Buildings
pressure between a specified outdoor sound field and the
E 413 Classification for Rating Sound Insulation
resulting sound pressure level in the room abutting the test
E 1332 Classification for Determination of Outdoor-Indoor
facade or facade element. The outdoor sound field and its
Transmission Class
This guide is under the jurisdiction of ASTM Committee E33 on Environmental
Acoustics and is the direct responsibility of Subcommittee E33.03 on Transmission. Annual Book of ASTM Standards, Vol 04.06.
Current edition approved January 10, 1999. Published May 1999. Originally
published as E 966 – 84. Last previous edition E 966 – 92.
E 966
A
TABLE 1 Application Guide to Measurement of Outdoor-Indoor Level Reduction (OILR) of Facade Elements
Calculation
Outdoor Signal Source Outdoor Microphone Position Reference Applications Remarks
Section
Calibrated loudspeaker at u5 45° Incident sound pressure inferred from separate 8.3.1, Fig. 1; Eq 4 Use when traffic noise is not available or
from test element calibration of source when outdoor measurement at or near
facade is not possible.
Loudspeaker at u5 45° from test Several locations averaged about 1.2 m 2.4 m from 8.3.2, Fig. 2; Eq 5 Use when calibrated source or flush
element the facade element measurement is not possible.
Loudspeaker at u5 45° from test Several locations less than 17 mm from facade 8.3.3, Fig. 3; Eq 6 Use when traffic noise is not available and
element element when loudspeaker cannot be calibrated.
Traffic or equivalent Simultaneous measurement remote from the facade 9.5.1, Fig. 4; Eq 8 Source far from facade (that is, consistent
traffic or aircraft overflights).
Traffic or equivalent, moving parallel Simultaneous measurement 2 m (79 in.) from facade 9.5.2, Fig. 5; Eq 9 Suitable when facade faces traffic. Smooth
with facade or rough facades. OILR and OITL down to
80 Hz.
Traffic or equivalent, moving parallel Simultaneous measurement less than 17 mm from 9.5.3, Fig. 6; Eq 10 Smooth or rough facade element test (for
with facade facade surface example, window, wall air conditioner, etc.);
OILR & OITL to 5000 Hz.
A
See 5.1, 8.3 and 9.2.
FIG. 3 Geometry—Flush Method
FIG. 1 Geometry—Calibrated Source Method
FIG. 4 Geometry—Equivalent Distance Method
FIG. 2 Geometry—Nearby Average Method
2.2 ANSI Standards:
S1.31 Precision Methods for the Determination of Sound
S1.4 Specification for Sound Level Meters
Power Levels of Broadband Sources in Reverberation
S1.11 Specification for Octave-Band and Fractional-Octave
Rooms
Analog and Digital Filter Sets
2.3 IEC Standards:
IEC Publication 651—Sound Level Meters
IEC Publication 804 Integrating-Averaging Sound Level
Available from the American National Standards Institute, 11 W. 42nd. St., 13th
Floor, New York, NY, 10036. Meters
E 966
specified angle, u, as defined in Fig. 2, to the sound power
transmitted through it and radiated to the interior; the quantity
so obtained is expressed in decibels (dB).
3.2.5.1 Discussion—The unqualified term OITL (u) signi-
fies that flanking tests have been performed according to Annex
A1 to verify that there was no significant flanking or leakage
transmission. In the absence of such tests, the test result may be
termed the apparent OITL (see 3.2.1).
3.2.6 traffıc noise—noise emitted by moving transportation
vehicles, such as cars, trucks, locomotives, or aircraft.
4. Summary of Guide
4.1 This guide provides procedures to measure the reduction
in sound level from the outdoors to an enclosed room. This
FIG. 5 Geometry—2 m (79 in.) Position Method
outside-inside level reduction is a function of angle, OILR (u),
where u is the angle of incidence of the outdoor sound. With
further measurements under restricted conditions, a basic
property of a facade or facade element, the outdoor-indoor
transmission loss, OITL (u), may be determined. This requires
that the conditions of Annex A1 be met to demonstrate that
flanking of sound around the test specimen is not significant. If
it is not possible to meet the conditions of Annex A1, the
apparent OITL (u) is reported. The OILR (u) and OITL (u) may
reported for a range of angles.
4.2 Sources of Test Signal:
4.2.1 The outdoor sound pressure level produced by a
loudspeaker source is either inferred from a previous calibra-
tion of the level emitted by that loudspeaker at a specific
distance, or it is measured near the facade, or it is measured
FIG. 6 Geometry and Formulas—Line Source Flush Method
flush to the facade. When the outdoor sound level is measured
near the facade, measurements shall be averaged over several
3. Terminology
locations near the test specimen to minimize effects of incident
3.1 Definitions—For acoustical terms used in this guide, see
and reflected sound wave interference.
Terminology C 634.
4.2.2 In the traffic noise method, movement of sources
3.2 Definitions of Terms Specific to This Standard:
along a line such as a highway or flight path combined with
3.2.1 apparent outdoor-indoor transmission loss, apparent
time averaging will minimize interference effects. To account
OITL (u)—the value of outdoor-indoor transmission loss ob-
for source fluctuations using the traffic noise method, the
tained on a test facade element as installed, without flanking
incident sound is measured synchronously with the indoor
tests to identify or eliminate extraneous transmission paths; the
levels.
apparent OITL is the lower limiting value of the outdoor-
4.3 To avoid propagation anomalies and extraneous noise
indoor transmission loss of the facade element.
sources, the measurements shall be made without precipitation
3.2.2 coincidence transmission—transmission loss which is
and when the wind speed is less than 5 m/s (11 mph).
especially angular dependent (see 8.2.3.2).
4.4 Measurements are preferably conducted in a series of
3.2.3 field outside-inside transmission class, FOITC—the
one-third octave band frequencies from at least 80 to 5000 Hz.
single number rating obtained by Classification E 413 or
Octave band data in the same frequency range are optional.
E 1332 with the OITL values.
NOTE 1—Where A-weighted OILR values are desired, A-weighted
3.2.4 outdoor-indoor level reduction, OILR—in a specified
measurements may be used. These values shall be reported as A-weighted.
frequency band, the difference between the time-averaged
exterior sound pressure and the space-time average sound
5. Significance and Use
pressure in a room of a building.
5.1 The OILR and OITL produced by the methods described
3.2.4.1 Discussion—The direct field sound pressure is from
will not correspond to the transmission loss and noise reduction
a sound source at a specified angle of incidence, u, as defined
measured by Test Method E 90 and E 336 because of the
in Fig. 2, or a range of angles in the case of a moving source,
different angular distributions that may exist in the outdoor
which would be present at the facade of the room, were the
incident sound fields (1) and the sound intensity distribution
building and its facade not present.
across the test facade. Of the three methods cited for measuring
3.2.5 outdoor-indoor transmission loss, OITL (u)—of a
building facade element in a specified frequency band, ten
times the common logarithm of the ratio of airborne sound
The boldface numbers in parentheses refer to a list of references at the end of
power per unit area incident on the facade element at a this standard.
E 966
the outdoor sound field from a loudspeaker, the free and flush hard wall, ceiling, and floor surfaces. For furnished rooms, it
methods are more repeatable. The near method is used only should be reported whether the absorption exceeds that given
when the free field and the flush methods are not feasible. by the following equation:
5.2 Flanking transmission or unusual field conditions could
2/3
A 5 V (1)
render the determination of OITL difficult or meaningless.
Where the auxiliary tests described in Annex A1 cannot be
where:
3 3
satisfied, only the apparent OITL or the OILR are to be
V 5 room volume, m (ft ), and
A 5 absorption, metric sabins (sabins).
considered valid.
7.4.2 Measurement of the Receiving Room Absorption, A :
6. Conditions Required to Typify the Characteristics of a
7.4.2.1 Reverberation Method (see Test Method C 423)—
Facade Element
The value of A is derived from measurements of the rate of
6.1 The facade under test is usually the whole segment of decay of sound pressure level in the receiving room, employing
exterior wall common to and enclosing one room (the receiving
a sound source in the receiving room. The Sabine equation
room). A facade element under test would be only a part of that leads to the following equation:
facade. The room selected for test should be surrounded with
A 5 0.921 Vd/c (2)
equal or better construction, with no obvious leakage paths
where d is the rate of decay of reverberant sound in the
such as open windows in adjacent spaces. Rooms at the top of
room, dB/s, or 60 dB/T, where T is the reverberation time of
a multi-story building might be unsuitable for testing because
the room, s.
of flanking transmission through the roof. A room at the corner
The speed of sound in the receiving room will change with
of a building may be undesirable since sound penetrating the
air temperature. It must be calculated, m/s, as follows:
adjoining exterior wall may be difficult to assess.
c 5 20.047 273.05 1 t (3)
6.2 If a relatively massive facade contains a low-mass =
element such as a window, the latter could be considered the
were t is the air temperature in degrees Celsius.
element under test on the assumption that it transmits a greater
8. OILR and OITL Measurement with a Fixed
amount of incident sound. A decision should be made whether
(Loudspeaker) Source
the test element size is to be defined with or without its
8.1 Measurement Site Background Noise—Indoor and out-
perimeter joints and framing.
6.3 Flanking measurement according to Annex A1 should door levels produced by the loudspeaker should be at least 5 dB
above the respective background noise levels in all measure-
be made blocking the element under test as defined in 6.2. This
test determines the degree to which sound transmits through ment bands. If the level produced by the test loudspeaker is
between 5 and 10 dB above the background level, adjustments
the remainder of the facade. The OITL may be computed with
the result of Eq A1.1, and so stated in the report according to for background noise must be applied according to Section 10.
It may be necessary to conduct measurements during periods of
13.1.2.
low indoor and outdoor noise to meet these requirements.
7. Properties of the Receiving Room Required to
8.2 Generation of Outdoor Sound Field:
Determine OITL(u) or Apparent OITL(u)
8.2.1 Loudspeaker So
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