Petersen-An Overview of Standards for Sound Power Determination

7/22/2019 Petersen-An Overview of Standards for Sound Power Determination

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An Overview of Standards for Sound Power Determination

by Erik Cietus Petersen, Bruel&Kjser, Denmark

f In Europe, a new "Machinery DirecAtive" has been written, coming intoforce from 1/1/95 (see Appendix C). The

purpose of th is directive is to ensurethe health of people using machines.

The directive states, among otherthings, that equipment sold in Europemust fulfil specified noise demands.The equipment covered by this directive is everything from jacks and garden tractors, to chain saws and plastic

moulding machines.What should be stated in the in

struction manual for the equipment?If the A-weighted sound pressure

level is below 70 dB(A), this must beindicated (L


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I^v = L p + ( Lw r e f - L p re f ) International Classification Test Character of Sound power

Standard ofmethod environmen t noise levels

As an introduction to the ISO 3741- obtainable

47 / ANSI S12.31-36 standards, ISO , o n Q 7 / M D . . " Ct , . . ,on,A/ AMOTomoA J IS03741 Precision Reverberation Steady, broad- In one or third3740 / ANSI S12.30 gives a very good .. , . ' , , ,6

i n /r o o m meeting band octave bands.

overview of the various me th ods (see specified Optional"Table 1). ISO 3742 requirements Steady discrete A-weighted

frequency ornarrow-band

t^^^L^mmi^ I I M II M M. 1 ii ii u u _ . i i h i i i IM i ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ H ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ . n , , M , . M ,, , M w r ^ r ^^^^ ^^^^^^^

n - i A/TafV in rl 1S03743 Engineering Special Steady, broad- A-weighted and- U l i e c i i v i e i i i o a reverberation band, narrow- in octave bands

test room band discrete-

1.1.1. Precision Methods ofSound freqPower Determination in a ~^T^TA t . " " . . . , T~ , . ISO 3744 Outdoors or in Any A-weighted andReverberant Room | a r g e r o o m i n o n e o rt h i r dPrecision methods (grade 1) ofsound octave bands

pow er de te rmi na ti on in a reverbera- ISO 3745 Precision Anechoic ortion room ar e governedby the stand- semi-anechoicard s ISO 3741 , ISO 3742, ANSI ^

S12.31, ANSI S12.32 and DIN 45 1S03746 Survey No special test A-weighted635-2. The measurement methods of environmentISO 3741 andISO 3742 are the same. The difference be tw een th em being IS03747 No special test Steady, broad-

ISO 3741 andANSI S12.31 are for environment; band, narrow-i i ! ! . l-i source under bandorbr oad- ba nd noise sources, while discrete-freqISO 3742, ANSI S12.32 and DI N 45 ^ V ab | e635-2 are fornarrow-band noise I I I I Isources an dplace more stringent re - Table 1quirements on the characteristics ofthe room. In the standards two methods ar e described, the direct methodan d the comparison method.

In the direct method, the soundpower is calculated from the spatiallyaveraged source, the backgroundnoise measurements and the physical

parameters ofthe room (volume, sur

face area and reverberation time).Note tha t the reference sound sourcecan be used to determine the acoustic

pr oper ti es ofthe room.

Instrumentation: Nin appendix A

1.1.2. Engin eerin g Methods of Sou nd

Power Determination in a

Reverberation Room

The engineering methods (grade 2) ofsound power determination in a re verberation room are governed byISO 3743, DIN45635-3 and ANSIS12.33. In these standards, the requirements for the reverberationroom are "relaxed" with respect toISO 3741/42 and ANSI S12.31/32.Fur the r the reverberation time of the Fig. 3 The parallelepiped or"shoebox" measuring surface used in ISO 3744

room is characterised as a singlenumber (the so-called nominal rever

be ra ti on ti me of the room, see ISO

3743/ANSI S12.33 fordetails), rather c u r a c y w i t h r e s p e c t to ISO 3741/42 The direct method ofISO 3743 andthan being variable with frequency. a n d ^ ^ S 1 2 3 1 / 3 2 ANSl S12,33 i s simplified with re -If the correction factor is unknown, a g p e c t t o ^ d i r e c t m e t h o d o f T g 0reference sound source can be used Like IbO 3741/42 IbO 3743 an d ^ ^ ^ ^ m ^ S12.31/32.to determine the acoustic prope rtie s ANSI S12.33 describe both a direct . . .

in ,T , , , i ,T n ^ ,i T i , i ir Instrumentation: N in appendix A

of the room. Note, however, th at ISO meth od anda comparison method tor

l

*3743/ANSI S12.33 gives reduced ac- determination ofsound power.

3

InternationalStandard

Classificationof method

Testenvironment

Characterofnoise

Sound powerlevels

obtainable

ISO 3741 Precision Reverberationroom meetingspecified

requirements

Steady, broadband

In one orthirdoctave bands.Optional:A-weightedISO 3742

Precision Reverberationroom meetingspecified

requirements Steady discretefrequency ornarrow-band

In one orthirdoctave bands.Optional:A-weighted

ISO 3743 Engineering Specialreverberationtest room

Steady, broadband, narrowband discrete-freq.

A-weighted andin octave bands

ISO 3744

Engineering

Outdoors or inlarge room

Any A-weighted andin one orthirdoctave bands

ISO 3745 Precision Anechoic orsemi-anechoicroom

Any A-weighted andin one orthirdoctave bands

ISO 3746 Survey No special testenvironment

Any

A-weighted

I SO 3747

Survey

No special test

environment;source undertest notmovable

Steady, broad

band, narrowband ordiscrete-freq.

A-weighted


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1.2.1. Precision Method of Sound not, be applied, since the y req uire too ver bera tion room is measured withPower Determination in an much effort. the reference sound source opera ting,Anechoic or Semi-anechoic The noise source can emit any kind i n order to obtain the room correctionChamber of noise: broad -band , nar row- band or factor. The source noise can the n beThe precision method ofdetermi na- discrete tones, and the mea sur eme nt meas ured in the same way by replac-tion of sound power in an anecho ic or surface c an be either a hemis phere ing the reference with the unknow nsemi-anechoic chamber is governed or a "shoebox". soun d source.

by IS O 3745, ANSI S12.35 an d DI N Instrumentation: O in appendix A Based on the sound power values45 635-1. It requ ires me as ur em ent of from the calib ratio n cha rt for the ref-

the oper atin g noise source and the erence source, and the two spat iallyba ck gr ound noise. Th is is done at a # averaged sound pressure level spec-number of microphone positions on a Comparison Method t ra , it is possible to determine thespherical mea sur eme nt surface sound power from the unknownaround the noise source under inves- 2.1.1. Precision Methods of sound source.tigation (anechoic chamber), oron a Sound Power Determination in Instrumentation: K, Min appendix Ahemispherical measurement surface a Reverberant Roomif the noise source is mounted on a Precision methods (grade 1) of sound 2.1.2. Engineering Methods of Soundreflecting plan e (semi-anechoic cham- power det erm ina tion in a reverbera- Power Determination in a

ber) . tion room ar e governed by the sta nd - Reverberation RoomInstrumentation: L in appendix A ards ISO 3741, ISO 3742, ANSI The engi neer ing meth ods (grade 2) of

S12.31, ANSI S12.32 andDIN 45 sound power determination in a re -1.2.2. Engineering Method of Sound 635-2. The measurement methods of verberation room are governed byPower Determination in an Almost- ISO 3741 and ISO 3742 ar e th e sam e. ISO 3743, DI N45 635-3 a nd ANSI

free-field over a Reflecting Plane The difference betwe en th em being S12.33. In these standards, the re-The engineering method ofsound tha t ISO 3741 and ANSI S12.31 are quire ments for the reverberationpower de te rm in at io n in an almost- f r broa d-ba nded noise sources, while room are "relaxed" with respect tofree-field is governed by ISO 3744, ISO 3742, ANSI S12.32 and DIN 45 ISO 3741/42 andANSI S12.31/32.ANSI S12.34 and DIN 45 635-1. This 635-2 are for narro w-band noise Furth er, the reverber ation time of theis a rela xati on of ISO 3745 and ANSI sources and place more str ing ent re- room is characterised as a singleS12.35 (hence reduced accuracy), in quirements on the characteristics of number (the so-called nominal rever-tha t it allows some deviati ons from the room. In the st and ar ds two met h- bera tion time ofthe room, see ISOtr ue free-field conditions and the use ds are described, the direct meth od 3743/ANSI S12.33 for details ), ra th erof mea sur eme nt surfaces other tha n and the comparison method. th an being variable with frequency.the sphe re and hem isp her e. One such In th e compari son metho d, the in- However, ISO 3743/ANSI S12.33me as ur em ent surface is the paral lel- faience of the envi ron ment on the de- gives reduc ed accuracy with res pectepiped, or"shoebox". Otherwise, the term inatio n is measured using a to ISO 3741/42 and ANSI S12.31/32.method is identical to ISO 3745 or reference sound source, e.g. Type ISO 3743 and ANSI S12.33 are

ANSI S12.35. Ifthe acoustic proper- 4204 (see Fig. 4). Firs t, the spat ially simi lar to ISO 3741/42 in that theyties of the room are unknown, a ref- averag ed sound pre ssu re in the re- describe both a direct method andaerence sound source can be usedtodetermine the correction factor.

Note the existence of a similarstandard (draft) ISO 3748, which hasnever been finally approved (1994).

Instrumentation: J, K, L, M in appen

dix A

1.2.3. Survey Method of Sound

Power Determination in an Almost-

free-field over a Reflecting Plane

The survey method (grade 3) of soundpower de te rm in at io n in an almost-free-field is governed by ISO 3746,ANSI S12.36 and DIN 45 635-1.These standards specify a surveymethod formeasuring the overallweighted sound pressure levels at

prescr ibed microphone posi tionsaround the noise source. The A-weighted sound power level is calculated from the measured values. Thismethod can be applied in situ tosources which cannot be moved to a _,. A _, . 7 . m7 _ 0 r t _>

. -, . , i rig.4 Complete system for sound power determination. Ine lype /b80 rrogram supportsspecial test environment and the the comparison method in the reverberant field according to ISO

methods specified m ISO 3741-45 and method in almost-free-field conditions according to ISO 3744. For ISO 3744 the Reference

ANSI S12.31-35 cannot, or should Sound So urcc Type 4204 is used, to determine the correction factor for the room

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comparison method for determination of sound power.

The comparison method describedin ISO 3743 and ANSI S12.33 is identical to the comparison method of ISO3741/42 and ANSI S12.31/32.

Instrumentation: K, M in appendix A

2.1.3. Survey Method of Sound

Power Determination using aReference Sound Source

The survey method of sound powerdetermination in accordance with thecomparison method is governed byISO 3747. The standard describes the

pr ocedure to be used for de te rm in in gthe overall A-weighted sound powerlevels of machines and equipmentwhich cannot be moved from their installed locations for acoustical testing

pu rp os es . A r eference sound source isuse d (see Fig. 5) whic h is placed in

the immediate vicinity of the source Fig. 5 Complete system for sound power determination. The Type 7680 Program supports

under test. the comparison method in the reverberant field according to ISO 3741143, and the directIt is not always simple to deter- method ln fJee1

oralmost-free-field conditions according to ISO 3744/45. Type 4204 is

, - I P , ! riot required when measuring according to lb(J 3/4bmine the mag nit ude 01 the environmental correction necessaryhowever, the comparison methodtakes it into account.

There are no restrictions on thetest environment or the shape andsize of the source. The noise emittedmust be steady, broad-band, narrow

ba nd or cont ain disc re te frequencies.Instrumentation: P, Q in appendix A

Determination of SoundPower based on SoundIntensity Measurementsaccording to the PointMethod

This method is governed by ISO9614-1, ANSI S12.21 and NF S31-100. These standards specify a method for measuring the component ofsound intensity normal to a measureme nt surf ace (see Fig. 6). The surfaceis chosen so as to enclose the noisesource(s) of which the sound powerlevel is to be determined. During thesound power determination, the intensity probe will be placed at anum ber of points (see Fig. 1 and 3).Each point is located on the measurement surface, representing a small

pa rt ia l ar ea , in which th e in te ns it yflow is constant. The octave, third-octave or band-limited A-weightedsound power level is calculated from

the measured values, lhe method is Fig.6 Measuring sound power in-situ using Sound Power Program Type 5304, Dual

applicable to any source for which a Channel Real-time Frequency Analyzer Type 2144, Sound Intensity Probe Type 3548 andphysical ly st at io na ry measurement Sound Intensity Calibrator Type 3541

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surface can be defined and the noise Igenerated by the source is stationary y*\

in time. The source is denned by the M>#

choice ofmeasurement surface. The J0?

method is applicable in situ, or in I p a i ^m^special purpose test environments. . . ^ ^ jsp Sound

A n u m b e r of c h e c k s ( f i e l d i n d k a - I I [ Real-time Frequency Analyzer .^^ProbT^

tors) ensure the quality of the sound | | 2144 my Z$A&power contribution from each meas- L ^ ^ ^ ^ J T br^V ^PI^^^F^TI /

urement point. This makes the deter- /,,K>.f^^^^\^ '"C""'' l!^^^M;--:

-:[ll ymination rather complicated, unless f/in\"""'-Yi\X^SEE&K ^ a ^ ^ ^ ^ i j l *a c o m p u t e r i s u s e d t o p e r f o r m a l l t h e Personal Computer

calculations. rt \\Sound Power Program -1L

T h e I S O 9 6 1 4 - 1 a n d A N S I S 1 2 . 2 1 5304and7679 Sound Intensity

standards support precision and en- nfi-3 Calibratorgineering grades, for octave and WLM

3541

third-octave bands, and survey grade 94i?75efor overall A-weighted only. .

Fig. 7 Complete system forsound power determination using sound intensity measure-Ihe French standard Nb bSl-Wi) ments. The Windows based PCsoftware Type 5304 and7679 makes sound power

is a s implif ied version ofthe I S O and determination, according to ISO 9614 parts 1 and 2 (the point andscanning method),A N S I standards support ing precis ion quick andeasyand engineering grade only.

Instrumentation: E, G or I in appen-

dix A

Determination ofSoundPower based on SoundIntensity Measurementsaccording to the ScanMethod

This method is governed by ISO

9614-2, ANSI S12.12, ECMA 160 andINSTA 121. These standards specify

a method for measuring the "spatial

averaged" component ofsound inten

sity, normal to a measurement sur

face. The surface is chosen so that it

encloses the noise source(s) for which

the sound power level is to be deter

mined. During the sound power de

termination, the intensity probe

traverses over the measurement sur

face (see Fig. 2). To simplify the mechanical movement (the scanning),

the measurement surface can be di- ff^/ulfil

/he

t ^ i n ^ directive, only the A-weighted Sound Power Level, here. - , - , . , , n .. , by. 3 ant A), is ofinterest, outthe spectrum may give an idea of how to reduce the noise level

vided into a number oi partial areas.

The octave, third-octave or band-limited A-weighted sound power level is

calculated from the measured values.

The method is applicable to any

source, in situ, or in special purpose

test environments, for which a phys

ically stationary measurement sur

face can be defined, and on which thenoise generated by the source is sta

tionary in time.

A number ofchecks (field indicators) ensure the quality ofthe sound

power contribution from each meas

urement surface. This makes the de

termination complicated, unless a pig.9 Reference Sound Source Type 4204 andElectroacoustic Calibrated Source Type

computer is used to perform all the 4205

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calcul ations. Due to the physi cal Note th at IEC 225 is und er revi- to fulfil ISO 9614/ANSI S12.21 andproperties of th e spat ia ll y averaged s i o n (1994) to adopt some of the tol- S12.12 precision and engineer ingscanning, the field indicator s are not erances from the 1986 ANSI SI.1 1 mea sur eme nts , where class 2 is in-as complicated to fulfil as the ones sta ndar d. tende d for survey meas ure ment s.needed for the point method. This I E C 6 5 1 a n d ^ g j g L 4 d es Cr ibesmakes the measurement much easier a n o r m a l exponential averagingto perform (see Fig. 8). sound level metei. where IEC 804 other Standards

governs the linear averaging.

The ISO 9614-2, ANSI S12.12 and Regardi ng sound power, the sped- T o d e t e r m i n e t h e s o u n d p o w e r l e v e l

ECMA 160 standa rds supp ort engi- fication of the overall A-weighted fil- o f & n o i g e g o u r c e ; t h e r e a r e & n u m b e r neeri ng grade for octave and third- ter is probably the most impor tant . o f d i f f e r e n t s t a ndards (describedoctave bands, and engineering and a b o v e ) t o c h o o g e b e t w e e n ( o f t e n r e .

survey grad e for overall A-weighted IEC 1043 and ANSI SI . 12 inst ru- ferred to as "Basic Sta ndar ds" or iustonly. ment atio n sta ndar ds describe the B-St andards ). The proper sound pow-

Instrumentation: F, H in appendix A minimum demands for sound inten- e r standard to choose, depends on thesity probes and analyzers. This is to a c o u s t i c environment and the equip-

The Nordic standard INSTA 121 is e n S U fr e * e a CC , U r a f f+

t h e m ^ u r e - m e n t a v a i l a b i e .,.n , . , , THA AATOT ment ol sound intensity applied toa simplified vers ion ol th e ISO, AJNbl >i i , r i

n -rf^,,. , i i mi the det ermina tio n of sound power in ~. ,. , ,. ,.and ECMA sta nda rds . Ih e meas ure- , .,, T o ^n ^ i H/ATMOT Operational Conditions, , i j. accordance with ISO 9614/ANSI *

ments and sound power determma- g l 2 2 1 & n d g l 2 1 T Q m e e t t h e r e_ Choosing one of th e above describedtion are made in the same way but i r e m e n t o f ^ s t m d a r d i n s t m . sta nda rds is very often not enough.the field indicators are limited to a m e n t g ^ r e q u i r e d to ^ ^ ^ T a k e for i n s t a n c e a c h a i n_s a w . A ll the

single test ol adequate mstrumenta- g o u n d i n t e n g i t i n o c t a y e o r t h i r d . o c_ sound power st an da rd s describe howtion capability. This makes sound tav e band s, and optionally to provide to determine the sound power, butpower de te rmin at ion simple to per- ^ ^ A_w e i M e ^ b a n d l e y e l s I t i g they do not say anything about theform, even without a computer. ^ ^ . ^ to m e a s u r e g o u n d p re g_ o p e r a t i o na l conditions. (See Fig. 10.)

Instrumentation: A, C or D in appen- g u r e iev e i ^ m add it io n to sound inten- For various types of equipm entrfiX sity level, to facilitate the use of the special sta nda rds exist, describing

field indicato rs described in ISO the conditions und er which the equip-Note that a proposal was ma de in 9614/ANSI S12.21 and S12.12 . The me nt should be te sted . This is to en-

1994 for the scannin g method: Deter- IEC/ANSI ins tru ment ati on sta ndar d sure an equal comparison betweenmination of sound power levels of describes two degrees of accuracy: competiti ve products on the mar ket .noise sources usi ng sound intens ity, class 1 and class 2. Class 1 is needed They are very often referred to asISO 9614-3, precision method.

Instruments used forDetermination of SoundPower

The sound power standards refer toa number of instru mentat ion standards governing sound intensity analyzers and intensity probes. Theinstrumentation standards specifystandardized filter curves, measurement and display set-up parametersand tolerances.

IEC 225 and ANSI SI.11 define theoctave, half-octave and third-octave

band filters for analysis of sound andvibration. Tolerances are also given.In 1966, the first edition was published. The tolerances outside thepass -band (filter sk ir ts ) were set highto make up for the analogue electronics used at that time. In 1986 camea revised version of the ANSI standard. The definitions of the filtercurves are the same, but the tolerances have been decreased, making

measurements less dependent on the Fig.10 Set-up for sound power determination of a Nilfisk industrial vacuum cleanerchosen filter manufacture. (Courtesy of Fisker& Nielsen A/S)

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"Noise Test Codes" orjust C-Stand- Air Terminals

ards . ISO 5135 defines req uir eme nts forTraditionally, standardization in acoustic testing in reverberation

acoustics has occurred intern ational - rooms ofair terminal units, dampersly. The machinery directive, however, andvalves used in airdiffusion andcalls for European Standards and for a i r distribution systems. It is based

pu re ly formal rea so ns , it has been on the use of ISO 3741/42. The stand -necessary to establish a European a r d describes the acoustic test facili-committee. They have decided to im- t i e s > instrumentation and procedures

pl em en t int er na ti on al s ta nda rds in t o b e u s e d f o r Precision grade deter-their original form. This is recogniz- n a t i o n {s Power levels inable in the way European standards o c t a v e o r third-octave bands, of a

u J j-i, T7-M- u noise source having a volume prefer-are numbered: the EN number is i n , ^ -.^ r ^ i rc n , , T nnnnn i IA T C ^ ably less than 1% ol t he volume olfound by adding 20000 to the ISO ,, J ,

, . the reverberation room.number!

Most of the specific C-Standards Fl-n EEC Machine Directive Label in--HI Chain-saws dicating the maximum sound power level

ar e at the moment European since I S 0 7 1 8 2 i f i es a m e t h o d f o r guaranteed by the manufacturer of thethere are no ISO counterparts lor the . *f, ,, . . , . , lawnmower

. n i c , . 0 . measuring the overall A-weigntedmany specific types ol machine. Since n , , , n ,^^^ ^ , 15 .,, andoctave band sound pressure lev-1957 several European committees , , ,-, , , r,. r, . _ els, at the operators position, ol noisehave prepared a large number of spe- e m i t t e d b rtabl na n d_h e ld, com-cific safety standards: Council Direc- b u g t i o n e n g i n e c h a i n_s a w s for u s e

tive 79/113 (year/number) EEC p r i m a r i l y i n f o r e s t s . This standardapplies to a broad range of machinery d o e g n o t c o y e r g o u n d p o w e r d e t e r m i_usedm work on civil engineering and n a t i o n j therefore it is important to

bu il ding si tes, 89/514 covers ea rth - f u l f i l t h e European Machinery Direc-moving mac hine s, 84/534 covers tow- tive ( s e e jgQ 9207).er cranes, 84/535 and 85/407 refer towelding generators, 84/536 and 85/Af,a r , , i n A / ISO 9207 specifies a method tor de-408 refer to power generators and 84/ . , . , / , T I Pcoo on/oco 00/10A 0Q/1O1 11 termming the sound power level ol538, 87/252, 88/180. 88/181 are all in , . b m i ,. i i -,' ' o T - 11 chain-saws. The standard providesre i e rence to l aw nmow ers .See l i g . i l . in ,, . r ,.all the information necessary to

In a couple or years(!) when the make, under standardized conditions,European standardization workofC- the determination, declaration andStandards is concluded, they will be verification ofsound power levels ofinternationally approved and the n hand-he ld chain-saws, primar ilyonly the ISO st an dar ds will exist. used in forests (see Fig. 14). Pref erred

A careful examination ofall exist- meth ods fordetermination of sounding C-Standards is beyond the scope P o w e r l e v e l s according to this stand-of this application note, bu t the fol- ard are engineering methods (grade y.g.12 Measurement surface surroundinglowing standards are mentioned just '' tabled. a personai computer

as examples:Sound Insulation

Business Equipment ISO 140-10 and NOR DTES T 1065-92

ISO 7779/ECMA 74 specifies a meth- S p e d f y & ^ T ^ f SUnd l n t e n S i t y- . , - . , . , scanning method ol measuring air-

od for th e measurement ol airborne , i . i , v n, , . borne sound insulation tor smallnoise emitted by computers and busi- huMmg elements. This method alsoness equi pmen t (Fig. 12). Unti l now, e s t a b l i s h e s d ir e C t l on S regarding re-

a wide variety ofmethods has been p o r t i n g a n d a p p l y i n g s u c h t e s t data.applied by individual manufactures T h e measurements are made underand users to satisfy particular equip- d i f f l l s e f i e l d c o n d i t i 0 ns. The Nordtestment or application needs. See standard is a simplified version of the

Fig- 1 3- ISO standard as it assumes thatThese diverse practices have, in there is no flanking transmission,

many cases, made comparison of hence, the measurements made ar enoise emission difficult. This stan d- simpler.ard simplifies such comparisons an dis the basis fordeclaration ofnoise Noise declaration

emission levels of computers and ISO 4871 is a standard under revi-bu si ne ss eq ui pm en t. See Table 2. sion (1994). This standard, which ap-

In order to ens ure accuracy, valid- plies to machinery andequipment: ^ ^ MeasuremeM of sound power on alty and acceptability, the standard is gives informat ion on the declara- personal computer showing the intensity

ba sed on ISO 3741/42/44/45. tion ofnoise emission values probe's path over the measurement surface

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J

- describes acousti cal and product I pro duc t: Computer Model ABC [ Iinforma tion to be st ated in tec hni- Declared Noise Emission Operating Idlecal documents supplied to users bythe manufacturer LwAd 7-1 B 7 -0B

LpA m (bystander position) 5 7 d B 5 6 d B

specifies th e met hod for verify ing I 1 1 1the declared noise emiss ion values Table 2 Example of declared noise emission values from ECMA Standard

stated by the manufacturer.

The values to be used for the dec- . . . ,

la ra tion of noise emission are th e Operating condition Lpm in dB Lw in dBoverall A-weighted sound power lev- idlinael, and the A-weighted emissionsound pressure level, at ope rat or or Full load

byst ande r pos it ions. The dec lared R .values are the stati stical upper limits I | |corresponding to the stated or la- Table 3 Acoustical date to be reported according to ISO 9207

bel led value defined in ISO 7574.

Together with ISO 3740-47 and ISO11200-11204, a complete system ofstandards is available which providea basis for establishing a specific machine noise measurement (noise test

code) for almost any situation.

ISO 7574 part 1 and 4 define termsrelating to methods for determiningand verifying the stated (e.g. la

belled) values of t he noise emit ted bymachinery and equipment. Part 2gives methods for stating values forthe individual machines (manufacture), and part 3 gives methods forverifying stated (labelled) values forba tches of mach ines .

DIN45 635DIN 45 635 is a Germ an sta ndar dwhich contains several hundredpa rt s. Part 1 to 3 are B-Standards

written in line with the ISO 374x Fig. 14 Position of chain saw during measurement to ISO 9207, is called a noise test

family, see above, but the rest are code. ISO 9207 describes the measurement conditions and recommends the standard,

Noise Test Codes for various types of according to which a measurement should be performed

machinery. The numbering is not consecutive, so numbers between 8 and3400 are usual. From Beuth VerlagGmbH, Berlin 30, it is possible to obtain the parts of the standard, and

as they will be able to supply not only mym

~

the international standards but also l l g L a ^ . : :. -942050e

domestic s tandards . Fig. 15 An example of Calibration

9

Product: Computer Model ABCDeclared Noise Emission Operating Idle

l-WAd

-PAm (bystander position)

7.1 B

57 dB

7.0 B

56 dB

Table 2 Example of declared noise emission values from ECMA Standard

Operating conditionLpm '" dB

Lw

in dB

Idling

Full load

Racing


10/12

Appendix Ainstrumentation

A Type 3554 Sound Inte nsit y System 2 x AO 0265 IEE E 488 Sta ndar d Digital Interface(contains Type 4437 + 3547 + 4231 + DP 0888 + CableWT9347 + WT9378) PC with IEE E interface run nin g Windows

B Type 3562 Sound Power Syst em M As set-up L plus(contains Type 2144 + 3548 + 3541 + 7679) Type 4204 Reference Sound Source

C Type 3563 Sound Inte nsit y Mapping System N Type 2123/33 Real-time Octave and Fract ional(contains Type 2133 + 3545 + ZH0 354 + 3541) Octave Digital Frequency Analyzer

Type 2669 B Falcon Microphone Preamplifi erD Type 2144 Portab le Real-time Frequency Analyzer Type 4192 Fal con Condenser Microphone

Type 3548 Sound Inte nsit y Probe Cartr idgeType 3541 Sound Int ens ity Cali brat or Type 3923 Rotating Microph one Boom

Type 4231 Sound Level CalibratorE Type 3563 Sound Int ens ity Mapp ing System Type 4204 Reference Sound Source

conta ins Type 2133 + 3545 + ZH0354 + 3541) AQ00 34 Remote Control CableType WT9378 Mapping and Sound Power ProgramAO 0265 IEEE 488 Sta nda rd Digital Interface Cable O Type 2236 Precision Inte grat ing Sound Level MeterPC with IEEE Interface run nin g Windows Type 4231 Sound Level Calibra tor

F Type 3562 Sound Power Sys tem P As set- up O plus(contains Type 2144 + 3548 + 3541 + 7679) Type 4204 Reference Sound SourceAO0265 IEEE 488 Standard Digital Interface CablePC with IEEE Q Type 2260 Inve sti gat or Modular Precision Sound

AnalyzerG Type 3554 Sound Int ens ity Syst em Type 4231 Sound Level Cal ibrator

(contains Type 4437 + 3547 + 4231 + DP 0888 + Type 4204 Reference Sound SourceWT9347 + WT9378)AO0265 IEEE 488 Standard Digital Interface CablePC with IEEE interface running Windows

H Type 3563 Sound Intensity Mapping System(contains Type 2133 + 3545 + ZH0354 + 3541)

Type 7679 Sound Power ProgramAO0265 IEEE 488 Standard Digital Interface CablePC with IEEE interface running Windows

I As set- up F plusType 5304 Sound Power Program

J Type 2143/44 Porta ble Real-time Frequency AnalyzerType 2669 B Falcon Microphone Preamplif ierType 4192 Falcon Condense r MicrophoneCartridgeType 3923 Rotating Microphone BoomType 4231 Sound Level CalibratorAO0265 IEEE 488 Standard Digital Interface Cable

PC with IEEE interface running Windows

K As set-up J plusType 4204 Reference Sound Source

L Type 2143/44 Portab le Real-time Frequency AnalyzerType 2822 Microphone Multiplexer10 x Type 2669 B Falcon Microphone Preamplifier10 x Type 4192 Fa lcon Condense r MicrophoneCartridge Type 4231 Sound Level CalibratorType 7680 Sound Power ProgramAO0087 BNC Coaxial Cable

10


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Appendix B

Determination of Sound Power based on Sound Pressure Measurements:

ISO 3740 Guide lines for the use of basic standa rd s and for the pre par ati on of noise te st codesISO 3741 Precision method for Broad-band sources in reverbe ratio n roomsISO 3742 Preci sion metho d for discrete frequency and nar row band sources in reverbera tion roomsISO 3743 Engine ering method s for special reverb eratio n test roomsISO 3744 Eng ineeri ng metho d for free-field conditions over a reflecting planeISO 3745 Preci sion meth od for anechoic and semi-anechoic roomsISO 3746 Survey methodISO 3747 Survey meth od using a reference sound sourceANSI S12.30 Revised version of ANSI S1.30. Equ iva len t to ISO 3740ANSI S12.31 Revised version of ANSI S1.31. Equivalent to ISO 3741ANSI S12.32 Revised version of ANSI S1.32. Equi valent to ISO 3742ANSI S12.33 Revised version of ANSI S1.33. Equivalent to ISO 3743ANSI S12.34 Revised version of ANSI S1.34. Equ iva len t to ISO 3744ANSI S12.35 Revised version of ANSI S1.35. Equ iva len t to ISO 3745ANSI S12.36 Revised version of ANSI S1.36. Equ iva len t to ISO 3746DIN 45 635-1 Similar to ISO 3744/45/46DIN 45 635-2 Similar to ISO 3741/42DIN 45 635-3 Similar to ISO 3743

Determination of Sound Power based on Sound Intensity Measurements:

According to the point method:

ISO 9614-1 Dete rmina tion of sound power levels of noise sources using sound inten sity - Meas urem entsat discrete points, grade 1, 2 and 3

ANSI S12.21 Simi lar to ISO 9614-1NF S31-100 Fr ench st an da rd , grade 1 and 2

According to the scan method:

ISO 9614-2 Deter minat ion of sound power levels of noise sources using sound inten sity - Meas urem entsby scanning, grade 2 and 3

ANSI S12.12 Similar to ISO 9614-2ECDMA 160 Using computer equipmen t, simi lar to ISO 9614-2INSTA 121 Det erm ina tion of sound power levels of noise sources usi ng sound int ens ity - Scanning

method for use in situ

Instruments used for Determination of Sound Power:

IEC 651 Sound Level Mete rsANSI S1.4 Equ iva len t to IEC 651IEC 804 Inte grat ing - averaging Sound Level MetersIEC 1043 Ins tr ume nts for the meas ure ment of sound inte nsity - Meas urem ents with pairs of pres sure

sensing microphonesANSI SI.1 2 Equiv alent to IEC 1043IEC 225 Octave, half-octave and third-octave band nite rs intend ed for the analysi s of sound and

vibration. 1966, and under revision (1994) inspired by ANSI SI.11-1986ANSI SI. 11 1966 edition equivalent to IEC 225-1966. New version in 1986

Other Standards:ISO 7779/ECMA 74 Meas urem ent of airborne noise emitte d by computer and business equip ment

ISO 5135 Deter minat ion of sound power levels of noise from air term inal devices, air ter min al unit s,dampers and valves by measurements in a reverberation room

ISO 7182 Measu reme nts at the operator's position of airborne noise emitted by chain sawsISO 9207 Manually portable chain-saws with int ern al combustion engine - Dete rmina tion of sound

power levelsISO 140-10 Meas urem ent of sound insula tion in buildings and of building element s - Meas ure ment of

sound insulation of small building elementsNord te st 1065-92 Small building elements : Sound insula tion , in te ns it y scanning un de r labora to ry condit ionsISO 4871 Decla ration and verification of noise emission valu es of mach ine ry and equ ipm entISO 7574 Statis tical methods for deter minin g and verifying stat ed noise emission values of machiner y

and equipment (part 1-4)DIN 45 635 This Germ an sta nda rd contains several hun dre d par ts. Par ts 1 to 3 are B-St andar ds, see

above, but parts 8 to 3400 (or higher) are Noise Test Codes for various types of machinery

11


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Appendix C

The Machinery Directive port. Fur ther more , manufa cturer s are the state ment. Furt hermo re, a techni-In Europe , a new "Machinery Direc- allowed to exhibit equipment which cal dossier containing drawings, calcu-tive" has been wri tten , coming into does not fulfil the directive if it is writ- lations, tes t results and productforce from 1/1/95. The purpose of this ten on the mach ine. description, must be kept by the man-directive is to ensu re quality and the If a mac hin e does not fulfil th e re- ufacturer. The safety of the operator ishealth of people using machines and qui rem ent s given by the dir ective, emphasized in a numb er of subjects,also to ensure free tra de over th e gover nmen t auth ori ties mu st prohib- and one of them is the contents of the

boarders . This appendix gives a brief it the us e of th e mac hi ne in th e EU inst ruct ion ma nu al . Fo r Briiel&KjaBrintroduction to the contents of Machin- country. As a gua ra nte e th at the ma- this is of intere st because sound andery Directive 89/392/EEC and the up- chine fulfils th e direc tive, it mu st be vibra tion levels mus t be state d.dates 91/368/EEC, 93/44/EEC and 93/ labelled with the "CE" mar k, unl ess

68/EEC. Note th at Brtiel&KjaBr cannot it is sold second- hand . Possibility of sanctionsbe held responsible for any misinter- Note tha t component s for a la rger Th er e has been a lot of t al k about th epre tat i'on of t he following text. machine do not need to be CE mark ed . ri sk of an d go ve rnm en t sanction

The manufacturer just has to state against installing machine s or equip-Directives vs. Standards th at used in a specified configuration, me nt covered by th e Mac hinery Di-Most enginee rs are familiar with the complete assembly can be CE rective which is not CE labelled. Well,sta nda rds . St and ar ds can be int er na- marke d. To fulfil the safety require- the worst thi ng th at can hap pen istional or domestic, but commonly ments , this directive calls on a numb er eith er tha t gover nmen t autho riti esthey are wri tte n by engi neer s and of other directives, e.g. EMC- and closes down the factory unti l the il-techn icians associated with ind ust ry mains-supply directives. As documen- legal equi pme nt is gone or th at youror technica l high schools, to be used tation, the manufa cture r has to state, ins ura nce compa ny will not cover the

by th e sa me group of people in th e th at the equipment is produced in ha r- da ma ge s your il legal eq ui pm en t ma ysame envir onmen t. T he Directives mony with the stan dard s mentioned in have caused!are, on the other hand, completelydifferent. They are written by lawyers, to be used by government authorities giving uniformity in all EUmember states. Therefore the directives do not give any technical solutions, only what is needed whenselling a product.

It is important to notice that when

a directive has been written, it willnever be changed.

Directives are updated by issuingnew directives to be appended. Regarding the Machinery Directive, werecommend that you obtain the commended version of the directive,which can be bought either directfrom the "Office for the EU official

publ icat ions , L-2985 Luxemb ourg "(price: ECU 15), or from a local sup

pl ier (more than 30 co un tr ie s all overthe world).

Contents of the directiveThe Machinery Directive consists of14 articles and 7 appendices. The directive defines which machines andsafety components it covers, especiallydangerous machines, and the exceptions, e.g. ships, railways, airplanes Fig, 16 A wide range of machinery must fulfil the "Machinery Directive" to be markedand vehicles used for passenger trans- and sold, in the EU

Documents

Petersen-An Overview of Standards for Sound Power Determination