1、Designation: E 1573 09Standard 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 () indicates an editorial change since the last revision or reapproval.INTRODUCTIONThis test method is one of a set of standards for evaluating the acoustical per
3、formance 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 sound
4、.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 pr
5、essurelevels.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 in
6、 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 Standa
8、rds:2C 634 Terminology Relating to Building and Environmen-tal AcousticsE 1374 Guide for Open Office Acoustics and ApplicableASTM Standards2.2 ANSI Standards:3S1.11 2004 Specification for Octave-Band and Fractional-Octave Band Analog and Digital FiltersS1.43 1997 (R 2007) Specifications for integrat
9、ing aver-aging sound level metersIEC 61672 2002 Electroacoustics- Sound Level meters-part 1: specifications3. Terminology3.1 DefinitionsThe 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 m
10、asking soundsound within an office that reducesthe intelligibility of intruding speech and the distraction fromactivity noise. Masking sound may be produced by a maskingsound system, heating, ventilating, and air conditioning(HVAC) sources, or other sources.3.2.2 masking sound systemthe electronic e
11、quipment andloudspeakers used to generate, distribute, and produce maskingsound throughout an office space.3.2.3 spatial uniformitya condition where the sound pres-sure levels throughout a defined space do not vary significantlyfrom the arithmetic mean sound pressure level. The amount ofallowable va
12、riation is specified by others such as a consultant,designer, or owner.1This test method is under the jurisdiction ofASTM Committee E33 on Buildingand Environmental Acoustics and is the direct responsibility of SubcommitteeE33.02 on Open Plan Spaces.Current edition approved April 1, 2009. Published
13、April 2009. Originallyapproved in 1993. Last previous edition approved in 2002 as E 157302.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Su
14、mmary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.4 temporal uniformityat
15、a given position, a conditionwhere the average sound pressure level measured over a shorttime interval does not differ significantly from the averagesound pressure level measured over a long time interval. Theamount of allowable variation is specified by others such as aconsultant, designer, or owne
16、r.4. Summary of Test Method4.1 The spatial uniformity of the masking sound in an openoffice 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 l
17、evel. The temporaluniformity of the masking sound is determined by measuringtheA-weighted 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. Si
18、gnificance and Use5.1 Speech privacy in an open office is dependent on manyfactors (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
19、 at normal voicelevels. The four critical acoustical parameters of maskingsound are 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 todeterm
20、ine if the masking sound meets a particular specifica-tion.6. Test Space6.1 The test 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
21、The floor covering and all wall finishes shall be com-pletely installed prior to testing.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 th
22、e distribution of masking soundwithin the space. However, this test method may also 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, th
23、e maskingsound system, and any other noise sources,7.1.2 The sound due to the masking 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 s
24、ystem and other equip-ment, then the test procedures shall be carried out with themasking 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 thema
25、sking sound system alone, then the background soundpressure levels shall be at least 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
26、 raised above the design level to provide the propersignal to noise ratio. Care should 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 H
27、VAC system and other sound sourcesshall be operated at their noisiest and quietest settings orconditions.8. Test Instrumentation8.1 A sound level meter or analyzer shall be used thatconforms to, or is better than, Type I, ANSI S1.431997 (R2007) or class 1, IEC 616722002 for a Type 1 meter that hason
28、e-third octave band filters.8.1.1 The overall frequency response of the filters for eachtest band shall conform to ANSI S1.112004 for class 1 orbetter.8.2 Test data may be acquired on-site or recorded for lateranalysis. The recording device shall have a frequency responseof 61 dB from 80 to 10 000 H
29、z.8.3 Amicrophone with a frequency response of 62 dB from80 to 10 000 Hz shall be used. The microphone shall beoriented 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 a
30、verage 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 (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 fr
31、om the closestsurface and the location shall be described in the report.9. Procedure9.1 Four different acoustical parameters must be measuredin order to evaluate masking sound. These parameters are themasking sound spectrum, sound level, spatial uniformity, andtemporal uniformity. The masking sound
32、spectrum and levelmust be measured first to determine compliance with aspecified spectrum. A test procedure is specified 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. Suchsource
33、s, which might not be heard and are outside the masking soundfrequency range, may provide misleading A-weighted readings. 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
34、and Level:9.2.1 Measure the masking sound pressure levels at eachone-third octave band center frequency from 100 to 8,000 HzE1573092at 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.9.2.2 The one-third oct
35、ave band sound pressure levels at theselected locations shall be measured over a time period of atleast 4 s.9.3 Measurement of Spatial Uniformity:9.3.1 Measure over an interval of at least 4 s theA-weightedsound level of the masking sound. The number and location ofmeasurement positions is determine
36、d by a walk-through listen-ing test conducted in the office test area. Measurements shall bemade at locations where 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 %
37、of the locations beingwhere no change in the masking sound is detected.9.3.2 For furnished spaces, the measurement 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
38、ducts in theplenum, etc.) that may affect masking sound distribution. Theprovisions of 8.3.1 and 8.3.2 should be 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
39、population maximum, minimum, mean, and stan-dard deviation of the average values measured in 9.3.1 shall bedetermined.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 lo
40、cations in the open office.9.4.2 The maximum, minimum, and averaged A-weightedsound levels encountered during the 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
41、1-s intervals bythe meter.10. Report10.1 In order to allow comparisons of data obtained atdifferent installations 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 t
42、histest method. Any exceptions to this test method shall be noted.10.1.2 A statement explaining whether the testing 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 installa
43、tion and mounting details such asmounting height, spacing, orientation, and locations.10.1.4 A brief description 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
44、system needed tocomply with 7.3.10.1.5 Abrief description of the air handling system or otherambient sound sources 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 d
45、iffusers, ceiling height, structural systemabove or below the ceiling system, plenum depth, plenum ductwork, wall 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 in
46、cluding manufacturer, type and model, anddate of the last calibration.10.1.9 A complete description of all microphone 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 th
47、an 1 m (3.3 ft) froma vertical surface.10.1.11 A listing of the measured maximum, minimum, andmean A-weighted sound 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-we
48、ighted sound levelsrounded to the nearest decibel, measured for the evaluation ofspatial distribution.10.1.13 Alisting 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 o
49、ctave band sound pressure levels measured in anopen office environment has been determined to be 62dBwhen the measurements 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.12. Keywords12.1 A-weighted; masking sound; one-third octave band;one-third octave band sound pressure levels; open officesE1573093ASTM International takes no positio
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