ASTM E1374-06(2011)
(Guide)Standard Guide for Open Office Acoustics and Applicable ASTM Standards
Standard Guide for Open Office Acoustics and Applicable ASTM Standards
SIGNIFICANCE AND USE
This guide is intended for the use of architects, engineers, office managers, and others interested in designing, specifying, or operating open offices.
It is not intended to be applied to other than office environments, for example, open plan schools.
While this guide attempts to clarify the many interacting variables that influence office privacy, it is not intended to supplant the experience and judgment of experts in the field of acoustics. Competent technical advice should be sought for success in the design of open offices, including comparisons of test results carried out according to ASTM standards.
SCOPE
1.1 This guide discusses the acoustical principles and interactions that affect the acoustical environment and acoustical privacy in the open office. In this context, it describes the application and use of the series of ASTM standards that apply to the open office.
1.2 The values stated in inch-pound units are to be regarded as standard. The SI units in parentheses are provided for information only.
This standard does not purport to address all of 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 of regulatory limitations prior to use.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E1374 − 06 (Reapproved 2011)
Standard Guide for
Open Office Acoustics and Applicable ASTM Standards
This standard is issued under the fixed designation E1374; 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 (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
There are no full height partitions in an open-plan office to block sound transmission between
adjacent work stations. Instead, partial height barriers, a sound absorbing ceiling and absorption on
vertical surfaces are used to provide sound attenuation between individuals. These, in combination
with work station layout and appropriate levels of broad band masking sound are used to obtain
acceptable degrees of acoustical privacy.
1. Scope E1414 Test Method for Airborne Sound Attenuation Be-
tween Rooms Sharing a Common Ceiling Plenum
1.1 This guide discusses the acoustical principles and inter-
E1573 Test Method for Evaluating Masking Sound in Open
actions that affect the acoustical environment and acoustical
Offices Using A-Weighted and One-Third Octave Band
privacy in the open office. In this context, it describes the
Sound Pressure Levels
application and use of the series ofASTM standards that apply
to the open office.
3. Summary of Guide
1.2 The values stated in inch-pound units are to be regarded
as standard. The values given in parentheses are mathematical
3.1 Acoustical Privacy—The attenuation of sound between
conversions to SI units that are provided for information only
neighboring work stations in an open-plan office is typically
and are not considered standard.
much less than that potentially available between closed-plan
offices. Nevertheless, a degree of acoustical privacy can be
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the achieved if component selection and interaction are under-
responsibility of the user of this standard to establish appro- stood. A successful open plan office is the result of careful
priate safety and health practices and determine the applica-
coordination of the several components, ceiling, wall
bility of regulatory limitations prior to use. treatments, furniture and furnishings, heating, ventilating and
air-conditioning system, and masking sound system. (See
2. Referenced Documents
Section 7.)
2.1 ASTM Standards:
3.1.1 This guide delineates the role and interaction of the
E1110 Classification for Determination ofArticulation Class
several components and the application of the relevant ASTM
E1111 Test Method for Measuring the InterzoneAttenuation
Standards.
of Open Office Components
E1130 Test Method for Objective Measurement of Speech
4. Significance and Use
Privacy in Open Plan Spaces Using Articulation Index
4.1 This guide is intended for the use of architects,
E1179 Specification for Sound Sources Used for Testing
engineers, office managers, and others interested in designing,
Open Office Components and Systems
specifying, or operating open offices.
4.2 It is not intended to be applied to other than office
This guide is under the jurisdiction ofASTM Committee E33 on Building and
environments, for example, open plan schools.
EnvironmentalAcousticsandisthedirectresponsibilityofSubcommitteeE33.02on
Open Plan Spaces.
4.3 Whilethisguideattemptstoclarifythemanyinteracting
Current edition approved Nov. 1, 2011. Published December 2011. Originally
variables that influence office privacy, it is not intended to
approved in 1990. Last previous edition approved in 2006 as E1374 – 06. DOI:
10.1520/E1374-06R11.
supplant the experience and judgment of experts in the field of
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
acoustics. Competent technical advice should be sought for
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
success in the design of open offices, including comparisons of
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. test results carried out according to ASTM standards.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1374 − 06 (2011)
5. General Open Office Acoustical Considerations annunciators). Large typing pools or word processing centers
can generate A-weighted sound levels up to 80 dB. These
5.1 Introduction—Attenuation with Distance—In almost
activities should be contained in special work areas affording
anyenclosedspace,thereissomereductionofsoundlevelwith
adequate noise isolation from the surrounding open plan
distance. In many typical spaces, this decrease of sound level
spaces.
with distance is affected by sound reflections from the ceiling,
the walls, and floor. In the open plan office the goal is to
5.8 Undivided Workspaces—Acoustical comfort may be
maximize this loss with distance in order to improve acoustical
improved in undivided workspaces such as “bull-pen” offices,
privacy. This requires a highly absorbent ceiling, some absorp-
drafting rooms, and typing pools by the addition of acoustical
tion on the floor, and careful treatment of nearby vertical
absorption to horizontal and vertical surfaces, but no such
surfaces. The ideal is to approach the conditions of the
treatment alone will provide speech privacy.
outdoors, where there are no reflecting surfaces.
5.9 ASTM test methods exist for testing components and
5.2 Attaining acoustical privacy between work stations,
systems for open plan offices. These include measuring the
open or closed plan, is determined by the degree to which the
attenuation between work stations by the ceiling path , the
intruding sounds from adjacent work stations exceed the
effect of barriers such as furniture panels, the effect of flanking
ambient sound levels at the listener’s ear.
or reflections from vertical surfaces (see Test Method E1111),
measurement of masking sound in the open office (see Test
5.3 The sound pressure levels arriving at the listener’s ear
Method E1573), and the determination of the articulation class
from sources in adjacent work stations depend on the follow-
(see Classification E1110), that is a single number rating of
ing:
system component performance. Articulation class does not
5.3.1 The sound source amplitude, directivity, and orienta-
account for the effect of masking sound.
tion.
5.3.2 The total attenuation of the sound due to a combina-
5.10 Objective Determination of Speech Privacy—Test
tion of distance and shielding by intervening barriers.
Method E1130 describes a method of objectively measuring
5.3.3 The reinforcement of the direct sound due to reflec-
the speech privacy in open plan offices. It is based on a
tions from office surfaces such as the ceiling, furniture panels,
determination of the articulation index.
light fixtures, walls, and windows.
5.10.1 Articulation Index—The articulation index (AI) is a
5.3.4 The level of ambient sound at the listener’s ear. This
computational method for predicting the intelligibility of
will often be generated and controlled by a sound masking
speech for groups of talkers and listeners.TheAI is a weighted
sound system, but in certain positions and frequency ranges,
fraction representing, for a given speech frequency band and
heating, ventilating, and air conditioning equipment (HVAC)
noise condition, the effective proportion of the standard speech
may contribute significantly to the ambient sound level.
signal that is available at the listener’s ear for conveying
speech intelligibility.
5.4 The attributes in 5.3.1 through 5.3.4 apply regardless of
the source of the intruding sound. In the open plan, both office 5.10.1.1 The articulation index ranges from 0.00 to 1.00,
equipment and speech are the dominant intruding sources. In with 0.00 representing zero intelligibility and 1.00 complete
many cases, the provision for acceptable speech privacy is the intelligibility.
major concern.
5.10.1.2 Speech privacy may be described as confidential
when speech may be detected but not understood.
5.5 Office layout should be designed to avoid obvious noise
5.10.1.3 Speech privacy may be described as normal or
intrusion possibilities. Individual work stations should be
non-intrusive when effort is required to understand the intrud-
positioned relative to columns, walls, and each other to avoid
ing speech. Normal speech privacy may also be described as
uninterrupted sound paths between contiguous work stations.
the absence of distraction.
Occupant orientation is also important, because there is a
significant difference between the sound level when a talker 5.10.1.4 Confidential speech privacy occurs at anAI of 0.05
faces a listener versus the talker facing away from the listener, or less. Speech becomes more readily understood with AI
of the order of 9 dB. values greater than 0.20; at values greater than 0.40 there is
essentially no privacy.
5.6 Loud Noises— Distractions caused by raised voices or
loud office equipment usually cannot be controlled by normal
NOTE 1—Additional research is needed to verify the relation between
open office constructions. It is recommended that some closed the AI and the subjective judgement of normal privacy in the open plan.
(See the appendix of Test Method E1130.)
plan spaces be provided to contain such loud equipment or
enclose noise sensitive spaces such as conference rooms.
6. Components of the Open Plan Acoustical Environment
5.7 Problem Noise Sources—Computers, business
6.1 Ceilings:
machines, copiers, typewriters, and other noise generating
devices should be located in isolated (enclosed) rooms or areas 6.1.1 The sound absorbing characteristics required of the
to minimize their noise intrusion into the work station. Where ceiling plane for open plan systems are different than those for
this is impractical, care should be exercised in eliminating or privateofficesorconferencerooms.Inopenplanspaces,sound
minimizing the noise generation aspects. Telephones and from the source not controlled by part-height space dividers
“speakerphones”areafrequentproblem.Theformershouldbe travels toward the ceiling plane, where part can be reflected
equipped with flashing lights, rather than ringers (audible back into the adjacent work space. To minimize the reflected
E1374 − 06 (2011)
sound, the ceiling must absorb most of it. In private offices or soundinthefrequencyrangeofconcern.Aparticularlydifficult
conference rooms, some lesser absorption or greater reflection area to treat in this regard is the glass in the typical exterior
may be desirable. wall of the office area. Note that materials used to achieve
6.1.2 The sound barrier characteristics of the ceiling plane sound absorption usually are not effective sound barriers. The
helps provide spatially uniform masking sound from loud- interzone attenuation provided by a vertical surface can be
speakers located in the ceiling plenum. If the sound barrier determined in accordance with Test Method E1111. The single
performance is low or variable, it may lead to the perceptions number classification for a vertical surface is the Articulation
of “hot spots” in the masking sound. Some masking system Class (AC) determined in accordance with Classification
designs may compensate for these deficiencies or variations. E1110.
6.2.3 Sound Barriers— Reduction of sound transmission
NOTE 2—There is currently no accepted objective method of specifying
through barriers separating adjacent work spaces is normally
single-pass sound barrier performance of ceiling materials.
achieved by adding an impermeable septum to the center of the
6.1.3 Lighting fixtures mounted in the ceiling must be
barrier. Care must be exercised in eliminating any possible
chosen with care. Flat, lensed fixtures tend to reflect sound
“throughholes”offeringunencumberedpassagewaysforsound
specularly and should be avoided. Parabolic cell fixtures, are
to “leak” through to adjacent work spaces. The interzone
preferred because they tend to scatter incident sound. The
attenuation provided by a barrier can be determined in accor-
sound barrier characteristics of the fixtures should also be
dance with Test Method E1111. The single number classifica-
similar to that of the ceiling, to avoid masking sound “hot
tion for barriers is the Articulation Class (AC) determined in
spots” underneath them.
accordance with Classification E1110. Severe conditions, for
6.1.4 Other ceiling elements, such as return air grilles or
example, people being located in close proximity to each other
fixtures, must also be selected with care, to avoid leakage of
or high source levels, need to be assessed for unwanted sound
sound from the masking system or surface reflections of
transmission paths (“flanking”) or higher barrier performance.
incident sounds.
6.2.3.1 Flanking Transmission—Flanking can be controlled
6.1.5 In closed plan spaces frequently associated with open
by proper consideration of the height and length of the barrier,
plan areas, the absorption characteristics of the ceiling are of
the horizontal distance between adjacent barriers, and the
less importance than its sound barrier characteristics. An
sound absorptive characteristics of the adjacent barriers. The
accepted method of specifying this performance is by the
most practical method of reducing flanking is to employ
two-room method, in Test Method E1414, that evaluates the
vertical barriers that are as high and as long as possible. This
sound passing through one ceiling into the plenum and then
may be in conflict with the desire for “openness” or clear view
back down through the ceiling into the adjacent space. Where
through the office space. The clearance between the bottom of
open and closed plan spaces are adjacent, masking sound is
the barriers and the floor should be minimal, although this path
frequently useful for providing speech privacy in both spaces.
is not as critical as clearance above the barrier.
The barrier and absorption characteristics of the ceiling system
6.2.3.2 Barrier Height— Barrier heights of less than 60 in.
should be optimized where open and closed spaces will be
(1.5 m) are not effective in performing as acoustical barriers in
mixed.
open plan offices.As a general rule, barrier heights greater than
6.1.6 Test Method E1111 is the preferred method of deter-
80 in. (2 m) provide diminishing returns. “Tradeoff” decisions
mining the ceiling absorption characteristics. It is a component
in the determination of the required height against the original
test and is restricted to measurement with a fixed-height space
motive fo
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