1、Designation: E 1573 02Standard Test Method forEvaluating Masking Sound in Open Offices UsingA-Weighted and One-Third Octave Band Sound PressureLevels1This standard is issued under the fixed designation E 1573; the number immediately following the designation indicates the year oforiginal adoption or
2、, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.INTRODUCTIONThis test method is one of a set of standards for evaluating the acoustical pe
3、rformance ofcomponents or systems in an open office. The other standards in this set deal with the measurementof the sound attenuation between work stations provided by partial height space dividers, verticalsurfaces, and acoustical ceiling systems; speech privacy; and the evaluation of masking soun
4、d.1. Scope1.1 This test method specifies the procedures that can beused to evaluate the spatial and temporal uniformity ofmasking sound in open offices using A-weighted sound levels.It also specifies the procedure for evaluating the masking soundspectrum and level using one-third octave band sound p
5、ressurelevels.1.2 The results of this test method can be used to determineif the masking sound meets a particular specification for spatialand temporal uniformity if that specification is written in termsof A-weighted sound levels and if the masking sound meets aparticular spectrum shape and level i
6、n the office area.1.3 This test method must not be used to evaluate theacoustical environment in an office space. It is intended only toevaluate the masking sound in an office. This test method, forinstance, does not evaluate the low frequency rumble noisefound in some offices.1.4 This standard does
7、 not purport to address all of thesafety problems, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Stand
8、ards:C 634 Terminology Relating to Environmental Acoustics2E 1374 Guide for Open Office Acoustics and ApplicableStandards22.2 ANSI Standards:3S1.11 Specification for Octave-Band and Fractional-OctaveBand Analog and Digital FiltersS1.4 Specification for Sound Level Meters3. Terminology3.1 Definitions
9、The acoustical terminology used in thistest method is consistent with the definitions in TerminologyC 634.3.2 Definitions of Terms Specific to This Standard:3.2.1 masking soundsound within an office that reducesthe intelligibility of intruding speech and the distraction fromactivity noise. Masking s
10、ound may be produced by a maskingsound system, heating, ventilating, and air conditioning(HVAC) sources, or other sources.3.2.2 masking sound systemthe electronic equipment andloudspeakers used to generate, distribute, and produce maskingsound throughout an office space.3.2.3 spatial uniformitya con
11、dition where the sound pres-sure levels throughout a defined space do not vary significantlyfrom the arithmetic mean sound pressure level. The amount ofallowable variation is specified by others such as a consultant,designer, or owner.3.2.4 temporal uniformityat a given position, a conditionwhere th
12、e average sound pressure level measured over a shorttime interval does not differ significantly from the averagesound pressure level measured over a long time interval. The1This test method is under the jurisdiction of ASTM Committee E33 onEnvironmental Acoustics and is the direct responsibility of
13、Subcommittee E33.02 onOpen Plan Spaces.Current edition approved April 10, 2002. Published June 2002. Originallypublished as E 157393. Last previous edition E 157398.2Annual Book of ASTM Standards, Vol 04.06.3Available from American National Standards Institute, 25 West 43rd St., 4thFloor, New York,
14、NY 10036.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.amount of allowable variation is specified by others such as aconsultant, designer, or owner.4. Summary of Test Method4.1 The spatial uniformity of the masking sound in an open
15、office is determined by measuring the A-weighted averagesound level with a sound level meter or real time analyzer atseveral locations and comparing these values to the arithmeticmean sound level or to a specified level. The temporaluniformity of the masking sound is determined by measuringthe A-wei
16、ghted sound levels over an extended period of time atone or more locations. The masking sound spectrum and levelis determined by measuring the one-third octave band soundpressure levels at one or more locations.5. Significance and Use5.1 Speech privacy in an open office is dependent on manyfactors (
17、see Guide E 1374 for a discussion on open officeacoustical considerations). One of these factors is the maskingsound in the office. Without masking sound in the open office,confidential speech privacy is not possible at normal voicelevels. The four critical acoustical parameters of maskingsound are
18、its spatial uniformity, temporal uniformity, spectrumshape, and level. The measurement and determination of theseparameters are addressed in this test method.5.2 The results from this test method can be used todetermine if the masking sound meets a particular specifica-tion.6. Test Space6.1 The test
19、 space shall include the entire office area servedby the masking system, or as otherwise specified.6.2 The ceiling system of the test space shall be completelyfinished, including light fixtures and air diffusers.6.3 The floor covering and all wall finishes shall be com-pletely installed prior to tes
20、ting.6.4 To provide the most meaningful information concerningthe ability of the masking sound to provide consistent privacy,it is preferable to test with interior furnishings in place sincefurniture may influence the distribution of masking soundwithin the space. However, this test method may also
21、be usedfor unfurnished spaces.6.5 The office space shall be unoccupied during the tests.7. Test Signal7.1 The test signal used for this evaluation may be any ofthe following:7.1.1 The sound due to the HVAC system, the maskingsound system, and any other noise sources,7.1.2 The sound due to the maskin
22、g sound system alone, or7.1.3 The sound due to the HVAC system alone.7.2 If the intent is to evaluate the performance of thecombination of sounds from the masking sound system, soundsources associated with the HVAC system and other equip-ment, then the test procedures shall be carried out with thema
23、sking sound system adjusted as intended to be used in theoccupied space. The HVAC system should be operated at itsnoisiest and quietest settings or conditions.7.3 If the intent is to evaluate the performance of themasking sound system alone, then the background soundpressure levels shall be at least
24、 10 dB lower than the soundpressure levels of the masking sound signal. For the measure-ment of temporal or spatial uniformity, this may require thatthe sound pressure levels of the masking sound system betemporarily raised above the design level to provide the propersignal to noise ratio. Care shou
25、ld be taken not to overdrive themasking sound system, which may cause distortion.7.4 If the intent is to evaluate the performance of themasking sound generated only by the HVAC system and otherbuilding sources, the HVAC system and other sound sourcesshall be operated at their noisiest and quietest s
26、ettings orconditions.8. Test Instrumentation8.1 A sound level meter or analyzer shall be used thatconforms to, or is better than, ANSI S1.4 for a Type 1 meterthat has one-third octave band filters.8.1.1 The overall frequency response of the filters for eachtest band shall conform to ANSI S1.11 for O
27、rder 3 or higher,Type 1 or better.8.2 Test data may be acquired on-site or tape recorded forlater analysis. The tape recorder shall have a frequencyresponse of 61 dB from 80 to 10 000 Hz.8.3 A microphone with a frequency response of 62 dB from80 to 10 000 Hz shall be used. The microphone shall beori
28、ented with respect to the ceiling in the office per themanufacturers recommendation for the type of microphonebeing used.8.3.1 The microphone position(s) should be at ear-height forthe average seated person which is 1.2 m (4 ft) above the floor.8.3.2 The microphone position(s) should be at least 1 m
29、 (3.3ft) from any vertical surfaces such as walls, columns, desks, oroffice furniture. In the event that this criterion cannot be met,the selected location shall be as far as possible from the closestsurface and the location shall be described in the report.9. Procedure9.1 Four different acoustical
30、parameters must be measuredin order to evaluate masking sound. These parameters are themasking sound spectrum, sound level, spatial uniformity, andtemporal uniformity. The masking sound spectrum and levelmust be measured first to determine compliance with aspecified spectrum. A test procedure is spe
31、cified for determin-ing each of these parameters.NOTE 1Caution: Some computer monitors employ fly-back trans-formers that produce high sound levels around 16 000 Hz or higher. Suchsources, which might not be heard and are outside the masking soundfrequency range, may provide misleading A-weighted re
32、adings. Careshould be taken to minimize this problem by avoiding operating terminals,turning them off, or band limiting the A-weighting reading.9.2 Measurement of Masking Sound Spectrum and Level:9.2.1 Measure the masking sound pressure levels at eachone-third octave band center frequency from 100 t
33、o 8,000 Hzat three or more locations in the office test area. The measure-ment (microphone) locations shall not be closer than 2 m (6.5ft) from each other.E15730229.2.2 The one-third octave band sound pressure levels at theselected locations shall be measured over a time period of atleast 4 s.9.3 Me
34、asurement of Spatial Uniformity:9.3.1 Measure over an interval of at least 4 s the A-weightedsound level of the masking sound. The number and location ofmeasurement positions is determined by a walk-through listen-ing test conducted in the office test area. Measurements shall bemade at locations whe
35、re both a change in masking sound isdetected and at locations where no change in the maskingsound is detected. No less than five measurement locationsshall be selected with at least 50 % of the locations beingwhere no change in the masking sound is detected.9.3.2 For furnished spaces, the measuremen
36、t locations shallbe chosen to represent typical listening positions within theopen office environment and shall also include the effects ofitems (such as light fixtures, diffusers, large ducts in theplenum, etc.) that may affect masking sound distribution. Theprovisions of 8.3.1 and 8.3.2 should be
37、met. The number oflocations at each type of work station shall be representative ofthe mix of each type of work station that is found in the overallfloor space under evaluation.9.3.3 The population maximum, minimum, mean, and stan-dard deviation of the average values measured in 9.3.1 shall bedeterm
38、ined.9.4 Measurement of Temporal Uniformity:9.4.1 The temporal uniformity of the masking sound isdetermined by measuring the A-weighted sound levels over a1-min interval at one or more locations in the open office.9.4.2 The maximum, minimum, and averaged A-weightedsound levels encountered during the
39、 1-min interval shall benoted. The measured values shall be either obtained using theslow response on the sound level meter or may be obtainedfrom the sound pressure levels averaged over 1-s intervals bythe meter.10. Report10.1 In order to allow comparisons of data obtained atdifferent installations
40、 using this test method, the report shallinclude the following items:10.1.1 A statement, if true in every respect, that tests wereconducted in accordance with the provisions outlined in thistest method. Any exceptions to this test method shall be noted.10.1.2 A statement explaining whether the testi
41、ng wasintended to evaluate the masking sound provided by all soundsources or only a masking sound system.10.1.3 A brief description of the loudspeaker or soundradiator, including installation and mounting details such asmounting height, spacing, orientation, and locations.10.1.4 A brief description
42、of the masking sound systemincluding the means of generation and distribution of thesound, the electronic equipment, and operating details includ-ing any adjustments to the masking sound system needed tocomply with 7.3.10.1.5 A brief description of the air handling system or otherambient sound sourc
43、es that contribute to the masking sound.10.1.6 A brief description of the test space including perti-nent features (for example, ceiling material, suspension grid,light fixtures, ceiling diffusers, ceiling height, structural systemabove or below the ceiling system, plenum depth, plenum ductwork, wal
44、l and floor finishes, and any interior furnishings).10.1.7 A complete description of the test signal (see 7.1).10.1.8 A description of the instrumentation used to acquireacoustical data including manufacturer, type and model, anddate of the last calibration.10.1.9 A complete description of all micro
45、phone locationsselected for measurements, preferably shown on a floor plan ofthe space.10.1.10 A statement identifying the location and data thatwas taken at microphone locations closer than 1 m (3.3 ft) froma vertical surface.10.1.11 A listing of the measured maximum, minimum, andmean A-weighted so
46、und levels, rounded to the nearest decibel,for each location evaluated for temporal uniformity.10.1.12 A listing of the population maximum, minimum,mean, and standard deviation of the A-weighted sound levelsrounded to the nearest decibel, measured for the evaluation ofspatial distribution.10.1.13 A
47、listing and a graph of the average one-third octaveband sound pressure levels of the masking sound.11. Precision and Bias11.1 The precision of the A-weighted sound levels and theone-third octave band sound pressure levels measured in anopen office environment has been determined to be 62dBwhen the m
48、easurements are made by different operators usingdifferent instruments.11.2 The procedures in this test method have no biasbecause the values of spatial uniformity, temporal uniformity,and masking sound spectrum are defined only in terms of thistest method for the particular office space evaluated.1
49、2. Keywords12.1 A-weighted; masking sound; one-third octave band;one-third octave band sound pressure levels; open officesE1573023ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five
