ASTM E1111-92(1996)e1

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
e1
Designation: E 1111 – 92 (Reapproved 1996)
Standard Test Method for
Measuring the Interzone Attenuation of Ceiling Systems
This standard is issued under the fixed designation E 1111; 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.
e NOTE—Keywords were added editorially in September 1996.
INTRODUCTION
This test method is one of a series for the measurement and evaluation of acoustical parameters
affecting speech privacy in open-plan spaces. The maximum privacy theoretically available at normal
working distances in open-plan spaces, with partial height space dividers (screens), is insufficient to
cope with normal speech without the assistance of relatively elevated background masking sound
levels. Thus, the provision of adequate speech privacy in open-plan offices and schools is one of the
most difficult tasks in the architectural acoustics field. This test method provides a means of
objectively measuring the relevant acoustical characteristics of one component in the open-plan space,
the ceiling system.
1. Scope 1.4 The values stated in SI units are to be regarded as the
standard. The values given in parentheses are provided for
1.1 This test method is intended to provide measurements
information only.
of the sound reflective characteristics of ceiling systems when
used in conjunction with partial-height space dividers. This
2. Referenced Documents
arrangement is commonly used in offices and schools to
2.1 ASTM Standards:
achieve speech privacy between work zones in the absence of
C 423 Test Method for Sound Absorption and Sound Ab-
full-height partitions. This test method is applicable to any
sorption Coefficients by the Reverberation Room Method
ceiling configuration, including, for example, a pattern of
C 634 Terminology Relating to Environmental Acoustics
sound-reflective panels in an otherwise sound-absorptive ceil-
E 1110 Classification for Determination of Articulation
ing. This test method, as specified, is primarily restricted to
Class
measurements with a fixed space divider height of 1.50 m (60
E 1179 Specification for Sound Sources Used for Testing
in.), a ceiling height of nominally 2.70 m (108 in.), a source
Open Office Components and Systems
height of 1.20 m (48 in.), and microphone positions at 1.20 m
2.2 ANSI Standards:
(48 in.) height.
S1.6 Preferred Frequencies and Band Numbers for Acous-
1.2 Laboratory Accreditation—A procedure for accrediting
tical Measurements
a laboratory for purposes of this test method is given in Annex
S1.11 Specification for Octave Band and Fractional-Octave-
A1.
Band Analog and Digital Filters
1.3 This standard does not purport to address all of the
S1.12 Specification for Laboratory Standard Microphones
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
3. Terminology
priate safety and health practices and determine the applica-
3.1 Definitions of Terms Specific to This Standard:
bility of regulatory limitations prior to use.
3.1.1 interzone attenuation—at a specified position, for a
one-third octave band, the difference between the sound
pressure level at the nominal reference position 0.9 m (3 ft)
This test method is under the jurisdiction of ASTM Committee E-33 on
from the sound source and the sound pressure level at the point
Environmental Acoustics and is the direct responsibility of Subcommittee E33.02 on
in question.
Open Plan Spaces.
Current edition approved June 5, 1992. Published August 1992. Originally
3.1.2 nominal interzone attenuation—for a one-third
published as E 1111 – 86. Last previous edition E 1111 – 88.
This test method is similar to a procedure developed by the U.S. Government
General Services Administration, Public Buildings Service, designated 8PBS-C.2,
Test Method for the Sufficient Verification of Speech-Privacy Potential Based on Annual Book of ASTM Standards, Vol 04.06.
Objective Measurements including Methods for the Rating of Functional Interzone Available from the American National Standards Institute, 11 W. 42nd St., 13th
Attenuation and NC-Background.’ August 1972. Floor, New York, NY 10036.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E 1111
octave-band, at a specified point, the arithmetic mean interzone of the contribution of ceiling system reflection to the total
attenuation calculated using the interzone attenuation for the sound transmission.
point in question and for two adjacent positions 0.3 m (1 ft) to 4.2 When the test is conducted in a mock-up of a proposed
either side. For example, the nominal interzone attenuation at building or in a completed building, strict adherence to the test
the 3.0-m (10-ft) position is the arithmetic mean of the method may not be possible in that the conditions of ceiling
interzone attenuations at the 2.7, 3.0 and 3.3-m (9, 10, and height and plenum depth, etc., cannot be met because of the
11-ft) positions. building design. Under these circumstances, the measurements
apply only to that situation and other identical situations.
4. Summary of Test Method
5. Significance and Use
4.1 The test facility (Fig. 1) is essentially an expanse of floor
and ceiling in which all vertical surfaces have negligible sound 5.1 The substitution of moveable part-height space dividers
reflections. The facility may be set up in a laboratory, in a for fixed full-height partitions between work zones in open-
mock-up of a proposed building, or in a completed building. plan offices and schools may introduce problems of inadequate
The standard space divider is of such dimensions and construc- speech privacy or distraction between zones. A space divider
tion that sound generated on one side can reach a measuring placed between zones serves as a partial sound barrier, but its
point on the other side only by way of diffraction over the top effectiveness can be compromised by deflection of sound over
of the space divider and by reflection from the ceiling. With the the space divider by the ceiling. An evaluation of the sound
diffracted component fixed by the dimensions of the space reflective characteristics of a ceiling system may therefore
divider and by the height of the source and measurement serve as a useful design tool in providing the speech privacy
position, the difference between the sound levels measured on required in a given open-plan layout. Although the potential
each side of the space divider provides a comparative measure speech privacy may be limited by other components of the
FIG. 1 Ceiling Test Facility
E 1111
open-plan space, this document is concerned only with ceiling achieved as for the laboratory facility. This may be effected
system performance in association with a specified space either by enclosing the test area temporarily with highly
divider construction. absorptive panels, by covering nearby reflective vertical sur-
5.2 The provision of speech privacy in open-plan spaces is faces with such materials, or by choosing a test site that is far
dependent upon many factors, the most significant of which are removed from any reflective vertical surfaces.
the following: (1) the shadow zone of part-height space 7.2 The space divider shall be at least 4.5 m (15 ft) wide and
dividers and the diffraction of sound from the edges of space of substantially the same construction as for the laboratory
dividers; (2) the primary sound reflective properties of the facility.
ceiling system; (3) the level of masking sound present in the
8. Apparatus
space; and (4) the distance between speaker and listener.
8.1 Loudspeaker, enclosed in a small box, driven by broad-
NOTE 1—The first factor is standardized in this test method and the
band or random noise. The loudspeaker shall meet the speci-
third is eliminated. Experience has indicated that results obtained by this
fications and requirements of Specification E 1179.
test method may not fairly represent the speech privacy that may be
8.1.1 The generated sound power shall be adequate to
achievable with nonflat ceiling systems.
maintain one-third octave band sound pressure levels of at least
5.3 The significance of test results obtained by this test
10 dB above the ambient noise levels of the test facility and the
method must also be considered with regard to the attainable
internal noise levels of the measuring instrumentation at each
measurement accuracy. The attainment of speech privacy in the
of the desired measurement locations.
presence of masking noise is critically dependent upon sound
8.2 Microphone—The microphone shall meet the require-
level of the speech relative to the masking sound; a change as
ments of ANSI S1.12 and shall have a free field correction of
small as 2 dB in either the speech or masking sound may
not more than 2 dB for sound waves at all measurement
change the privacy from significant to insignificant perceived
frequencies incident on the microphone diaphragm from 30 to
speech intelligibility. The normally accepted test accuracies for
90°. The microphone shall be mounted vertically with the
sound attenuation measurements may be inadequate to evaluate
diaphragm pointing upwards.
ceiling systems having marginal interzone attenuation perfor-
8.3 Filters—Filters used with the microphone or source
mance for open-plan space needs.
amplifiers shall conform to ANSI Specification S 1.11 for
6. Laboratory Test Facility Order 3, Type 1, ⁄3 octave-band filters.
6.1 The area of the facility shall be preferably at least 4.5 by
9. Sampling
9 m (15 by 30 ft).
9.1 A ceiling system constructed as a specimen for this test
6.2 The floor shall be of a solid material such as concrete or
2 2
method will be a complex assembly of many component parts.
plywood weighing at least 20 kg/m (4 lb/ft ). It shall be
Therefore, a requirement for minimum sampling is impractical
covered with carpet without underpad typical of those used in
and not required. However, the individual components shall be
open plan spaces. The absorption coefficients of the carpet shall
randomly selected from normal stock.
be measured in accordance with Test Method C 423, and the
noise reduction coefficient (NRC) shall lie in the range from
10. Test Specimen
0.2 to 0.4.
10.1 The ceiling to be tested shall cover the entire area of
6.3 The walls shall have random incidence sound absorption
the laboratory facility, or at least a 4.5 by 9 m (15 by 30 ft) area
coefficients of at least 0.9 for all test frequencies.
in a field test facility. Its nominal level shall be 2.75 m 6 50
6.3.1 The wall covering sound absorption shall be measured
mm (9 ft 6 2 in.) above the floor, and it shall be suspended
in accordance with Test Method C 423 with a mounting
from a flat structural slab or deck with a plenum depth of not
equivalent to that used in the test facility.
less than 0.60 m (24 in.) with a preferred depth of 0.75 m (30
6.4 The space divider shall be 1.50 m (60 in.) high and shall
in.). The upper and perimeter surfaces of the plenum shall be
extend the full width of the facility between the side walls and
sound reflective. The plenum shall contain no ducts, beams, or
shall be placed at least 2.70 m (108 in.) from both end walls.
similar obstructions that will affect the test results. The nominal
It shall have a core of rigid, impermeable material weighing
2 2 ceiling level shall be defined as that of the exposed surface of
not less than 7.0 kg/m (1.4 lb/ft ), and shall be faced on both
a continuous flat ceiling, or of the lowest exposed surface of a
sides with a 50 mm (2.0 in.) thickness of sound absorbing
nonflat ceiling. If, in a field test situation, the ceiling height and
material. The core shall extend fully to the top of the space
plenum conditions cannot be met, this test method may be used
divider, as shall the sound absorption facing material. The
to evaluate the test setup and may not be used to obtain general
space divider shall have a minimum NRC of 0.80 when
interzone attenuation data for the ceiling system.
measured in general accordance with the provisions for testing
10.2 When the ceiling assembly includes differing elements
office space dividers in Test Method C 423. There shall be no
in the horizontal plane, such as light fixtures or varying ceiling
gap between the bottom of the space divider and the floor. If
levels, the orientation with respect to the space divider and the
the space divider is assembled in sections, care shall be taken
sound measurement survey line shall be described and re-
to minimize sound transmission at the joints.
ported.
7. Field Test Facility
NOTE 2—In a ceiling containing both sound absorptive and reflective
7.1 For tests in a field prototype or completed building, the
areas such as light fixtures, interzone attenuation values may vary widely
same degree of suppression of horizontal reflections shall be depending on the location of the survey line with respect to the ceiling
E 1111
layout. It is therefore advantageous to choose two or three survey lines in
identified. The minimum of these AC values may be reported
such a way as to yield both maximum and minimum attenuations. The
as the minimum articulation class, without a qualifying dis-
orientation and survey line for minimum attenuation shall always be
tance or location.
measured and reported.
13. Report
11. Procedure
13.1 Report the following information:
11.1 Place the sound source in a position above the floor,
13.1.1 A statement, if correct in every respect, that the test
facing the space divider and pointed upward at an angle of 25°
has been conducted in full accordance with this test method,
to the floor, so that the lower plane of a 50° included angle
13.1.2 A full description of deviations, if any, from this test
meeting the directional requirements of Specification E 1179 is
method,
parallel to the floor. Position the point where the loudspeaker
13.1.3 A complete description of the ceiling materials,
axis intersects the front plane of the loudspeaker enclosure 1.20
components, method of assembly, and configuration,
m (48 in.) above the floor at a distance of 1.80 m (72 in.) from
13.1.4 A description and drawing of the position and orien-
the space divider (Fig. 1).
tation of the survey line and space divider with respect to the
11.2 The sound signal should be noise with a continuous
horizontal configuration of the ceiling, and
frequency spectrum within each of the one-third octave bands
13.1.5 A tabul
...