1、Designation: E 1374 06Standard Guide forOpen Office Acoustics and Applicable ASTM Standards1This standard is issued under the fixed designation E 1374; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A nu
2、mber in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.INTRODUCTIONThere are no full height partitions in an open-plan office to block sound transmission betweenadjacent work stations. Instead, partial h
3、eight barriers, a sound absorbing ceiling and absorption onvertical surfaces are used to provide sound attenuation between individuals. These, in combinationwith work station layout and appropriate levels of broad band masking sound are used to obtainacceptable degrees of acoustical privacy.1. Scope
4、1.1 This guide discusses the acoustical principles and inter-actions that affect the acoustical environment and acousticalprivacy in the open office. In this context, it describes theapplication and use of the series of ASTM standards that applyto the open office.1.2 The values stated in inch-pound
5、units are to be regardedas standard. The SI units in parentheses are provided forinformation only.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health
6、 practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E 1110 Classification for Determination of ArticulationClassE 1111 Test Method for Measuring the Interzone Attenua-tion of Open Office ComponentsE 1130 Test Method for Object
7、ive Measurement of SpeechPrivacy in Open Offices Using Articulation IndexE 1179 Specification for Sound Sources Used for TestingOpen Office Components and SystemsE 1414 Test Method for Airborne Sound Attenuation Be-tween Rooms Sharing a Common Ceiling PlenumE 1573 Test Method for Evaluating Masking
8、Sound in OpenOffices Using A-Weighted and One-Third Octave BandSound Pressure Levels3. Summary of Guide3.1 Acoustical PrivacyThe attenuation of sound betweenneighboring work stations in an open-plan office is typicallymuch less than that potentially available between closed-planoffices. Nevertheless
9、, a degree of acoustical privacy can beachieved if component selection and interaction are under-stood. A successful open plan office is the result of carefulcoordination of the several components, ceiling, wall treat-ments, furniture and furnishings, heating, ventilating andair-conditioning system,
10、 and masking sound system. (SeeSection 7.)3.1.1 This guide delineates the role and interaction of theseveral components and the application of the relevant ASTMStandards.4. Significance and Use4.1 This guide is intended for the use of architects, engi-neers, office managers, and others interested in
11、 designing,specifying, or operating open offices.4.2 It is not intended to be applied to other than officeenvironments, for example, open plan schools.4.3 While this guide attempts to clarify the many interactingvariables that influence office privacy, it is not intended tosupplant the experience an
12、d judgment of experts in the field ofacoustics. Competent technical advice should be sought forsuccess in the design of open offices, including comparisons oftest results carried out according to ASTM standards.5. General Open Office Acoustical Considerations5.1 IntroductionAttenuation with Distance
13、In almostany enclosed space, there is some reduction of sound level withdistance. In many typical spaces, this decrease of sound level1This guide is under the jurisdiction ofASTM Committee E33 on EnvironmentalAcoustics and is the direct responsibility of Subcommittee E33.02 on Open PlanSpaces.Curren
14、t edition approved April 1, 2006. Published April 2006. Originallyapproved in 1990. Last previous edition approved in 2002 as E 1374 02.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume in
15、formation, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.with distance is affected by sound reflections from the ceiling,the walls, and floor. In the open plan office
16、the goal is tomaximize this loss with distance in order to improve acousticalprivacy. This requires a highly absorbent ceiling, some absorp-tion on the floor, and careful treatment of nearby verticalsurfaces. The ideal is to approach the conditions of theoutdoors, where there are no reflecting surfa
17、ces.5.2 Attaining acoustical privacy between work stations,open or closed plan, is determined by the degree to which theintruding sounds from adjacent work stations exceed theambient sound levels at the listeners ear.5.3 The sound pressure levels arriving at the listeners earfrom sources in adjacent
18、 work stations depend on the follow-ing:5.3.1 The sound source amplitude, directivity, and orienta-tion.5.3.2 The total attenuation of the sound due to a combina-tion of distance and shielding by intervening barriers.5.3.3 The reinforcement of the direct sound due to reflec-tions from office surface
19、s such as the ceiling, furniture panels,light fixtures, walls, and windows.5.3.4 The level of ambient sound at the listeners ear. Thiswill often be generated and controlled by a sound maskingsound system, but in certain positions and frequency ranges,heating, ventilating, and air conditioning equipm
20、ent (HVAC)may contribute significantly to the ambient sound level.5.4 The attributes in 5.3.1 through 5.3.4 apply regardless ofthe source of the intruding sound. In the open plan, both officeequipment and speech are the dominant intruding sources. Inmany cases, the provision for acceptable speech pr
21、ivacy is themajor concern.5.5 Office layout should be designed to avoid obvious noiseintrusion possibilities. Individual work stations should bepositioned relative to columns, walls, and each other to avoiduninterrupted sound paths between contiguous work stations.Occupant orientation is also import
22、ant, because there is asignificant difference between the sound level when a talkerfaces a listener versus the talker facing away from the listener,of the order of 9 dB.5.6 Loud Noises Distractions caused by raised voices orloud office equipment usually cannot be controlled by normalopen office cons
23、tructions. It is recommended that some closedplan spaces be provided to contain such loud equipment orenclose noise sensitive spaces such as conference rooms.5.7 Problem Noise SourcesComputers, business ma-chines, copiers, typewriters, and other noise generating devicesshould be located in isolated
24、(enclosed) rooms or areas tominimize their noise intrusion into the work station. Where thisis impractical, care should be exercised in eliminating orminimizing the noise generation aspects. Telephones and“speaker phones” are a frequent problem. The former should beequipped with flashing lights, rat
25、her than ringers (audibleannunciators). Large typing pools or word processing centerscan generate A-weighted sound levels up to 80 dB. Theseactivities should be contained in special work areas affordingadequate noise isolation from the surrounding open planspaces.5.8 Undivided WorkspacesAcoustical c
26、omfort may beimproved in undivided workspaces such as “bull-pen” offices,drafting rooms, and typing pools by the addition of acousticalabsorption to horizontal and vertical surfaces, but no suchtreatment alone will provide speech privacy.5.9 ASTM test methods exist for testing components andsystems
27、for open plan offices. These include measuring theattenuation between work stations by the ceiling path , theeffect of barriers such as furniture panels, the effect of flankingor reflections from vertical surfaces (see Test Method E 1111),measurement of masking sound in the open office (see TestMeth
28、od E 1573), and the determination of the articulation class(see Classification E 1110), that is a single number rating ofsystem component performance. Articulation class does notaccount for the effect of masking sound.5.10 Objective Determination of Speech PrivacyTestMethod E 1130 describes a method
29、 of objectively measuringthe speech privacy in open plan offices. It is based on adetermination of the articulation index.5.10.1 Articulation IndexThe articulation index (AI) is acomputational method for predicting the intelligibility ofspeech for groups of talkers and listeners. The AI is a weighte
30、dfraction representing, for a given speech frequency band andnoise condition, the effective proportion of the standard speechsignal that is available at the listeners ear for conveyingspeech intelligibility.5.10.1.1 The articulation index ranges from 0.00 to 1.00,with 0.00 representing zero intellig
31、ibility and 1.00 completeintelligibility.5.10.1.2 Speech privacy may be described as confidentialwhen speech may be detected but not understood.5.10.1.3 Speech privacy may be described as normal ornon-intrusive when effort is required to understand the intrud-ing speech. Normal speech privacy may al
32、so be described asthe absence of distraction.5.10.1.4 Confidential speech privacy occurs at an AI of 0.05or less. Speech becomes more readily understood with AIvalues greater than 0.20; at values greater than 0.40 there isessentially no privacy.NOTE 1Additional research is needed to verify the relat
33、ion betweenthe AI and the subjective judgement of normal privacy in the open plan.(See the appendix of Test Method E 1130.)6. Components of the Open Plan Acoustical Environment6.1 Ceilings:6.1.1 The sound absorbing characteristics required of theceiling plane for open plan systems are different than
34、 those forprivate offices or conference rooms. In open plan spaces, soundfrom the source not controlled by part-height space dividerstravels toward the ceiling plane, where part can be reflectedback into the adjacent work space. To minimize the reflectedsound, the ceiling must absorb most of it. In
35、private offices orconference rooms, some lesser absorption or greater reflectionmay be desirable.6.1.2 The sound barrier characteristics of the ceiling planehelps provide spatially uniform masking sound from loud-speakers located in the ceiling plenum. If the sound barrierperformance is low or varia
36、ble, it may lead to the perceptionsE1374062of “hot spots” in the masking sound. Some masking systemdesigns may compensate for these deficiencies or variations.NOTE 2There is currently no accepted objective method of specifyingsingle-pass sound barrier performance of ceiling materials.6.1.3 Lighting
37、fixtures mounted in the ceiling must bechosen with care. Flat, lensed fixtures tend to reflect soundspecularly and should be avoided. Parabolic cell fixtures, arepreferred because they tend to scatter incident sound. Thesound barrier characteristics of the fixtures should also besimilar to that of t
38、he ceiling, to avoid masking sound “hotspots” underneath them.6.1.4 Other ceiling elements, such as return air grilles orfixtures, must also be selected with care, to avoid leakage ofsound from the masking system or surface reflections ofincident sounds.6.1.5 In closed plan spaces frequently associa
39、ted with openplan areas, the absorption characteristics of the ceiling are ofless importance than its sound barrier characteristics. Anaccepted method of specifying this performance is by thetwo-room method, in Test Method E 1414, that evaluates thesound passing through one ceiling into the plenum a
40、nd thenback down through the ceiling into the adjacent space. Whereopen and closed plan spaces are adjacent, masking sound isfrequently useful for providing speech privacy in both spaces.The barrier and absorption characteristics of the ceiling systemshould be optimized where open and closed spaces
41、will bemixed.6.1.6 Test Method E 1111 is the preferred method of deter-mining the ceiling absorption characteristics. It is a componenttest and is restricted to measurement with a fixed-height spacedivider, fixed sound source height, and microphone positions.A single number rating, convenient for ra
42、nking the perfor-mance of the ceiling, is obtained using Classification E 1110.Specification E 1179 specifies the directional characteristics ofloudspeakers used in this and similar tests.NOTE 3Articulation class is the preferred measure of the absorptionproperties necessary for acceptable open plan
43、 ceiling performance; soundabsorption ratings derived from reverberation room measurements shouldnot be used.6.2 Sound Barriers and Vertical Surfaces:6.2.1 Sound generated within the work station and poten-tially intruding into adjacent work spaces is of major concern.This potentially intrusive soun
44、d is reduced in the following twoways: ( 1) using barriers that are properly absorptive andappropriately impervious to sound penetration, and (2) reduc-ing the tendency of sound to “flank” or diffract around theperimeters of such barriers.6.2.2 Sound Reflectors All vertical surfaces are possiblesoun
45、d reflectors if not specifically treated. Hard, flat, smoothsurfaces represent the worst condition. To reduce or eliminatethese reflections, such surfaces should be highly absorptive tosound in the frequency range of concern.Aparticularly difficultarea to treat in this regard is the glass in the typ
46、ical exteriorwall of the office area. Note that materials used to achievesound absorption usually are not effective sound barriers. Theinterzone attenuation provided by a vertical surface can bedetermined in accordance with Test Method E 1111. The singlenumber classification for a vertical surface i
47、s the ArticulationClass (AC) determined in accordance with ClassificationE 1110.6.2.3 Sound Barriers Reduction of sound transmissionthrough barriers separating adjacent work spaces is normallyachieved by adding an impermeable septum to the center of thebarrier. Care must be exercised in eliminating
48、any possible“through holes” offering unencumbered passageways for soundto “leak” through to adjacent work spaces. The interzoneattenuation provided by a barrier can be determined in accor-dance with Test Method E 1111. The single number classifica-tion for barriers is the Articulation Class (AC) det
49、ermined inaccordance with Classification E 1110. Severe conditions, forexample, people being located in close proximity to each otheror high source levels, need to be assessed for unwanted soundtransmission paths (“flanking”) or higher barrier performance.6.2.3.1 Flanking TransmissionFlanking can be controlledby proper consideration of the height and length of the barrier,the horizontal distance between adjacent barriers, and thesound absorptive characteristics of the adjacent barriers. Themost practical method of reducing flanking is to employvertical barriers that
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