1、ECMA EUROPEAN COMPUTER MANUFACTURERS ASSOCIATION PRODUCT NOISE EMISSION OF COMPUTER AND BUSINESS EQUIPMENT ECMA TRI62 June 1993 Free copies of this document are available from ECMA, European Computer Manufacturers Association, 114 Rue du Rhne - CH-1204 Geneva (Switzerland) Phone: 41 22 735 36 34 Fax
2、: 41 22 786 52 31 X.400: C=ch, A=arcom, P=ecma, O=genevanet, OUl=ecma, S=helpdesk Internet: helpdeskecmach ECMA EUROPEAN COMPUTER MANUFACTURERS ASSOCIATION PRODUCT NOISE EMISSION OF COMPUTER AND BUSINESS EQUIPMENT ECMA TRI62 June 1993 Brief history The acoustical conditions at work stations have rec
3、eived considerable attention as the amout of computer and business equipment installed at or in close proximity to work stations has increased. One of these influences is acoustical noise being emitted by the equipment. Depending on the level of the noise, different aspects may be of interest when r
4、ating its effects on man. At high levels, noise may cause hearing impairment, at lower levels it may be annoying, may interfere with speech communication, or may impair creativity. To control the noise in the working environment, several countries have established regulations and standards which def
5、ine maximum allowable noise levels to which an individual may be exposed during working hours. To achieve acceptable noise levels at a work station, two factors must be considered, acoustically well-designed machines and acoustical provisions in the environment itself. This implies that both users a
6、nd manufacturers are responsible for the acoustical conditions at the workplace. To facilitate communicatin between different parties involved in noise control, ECMA has established standards for the measurement and declaration of product noise as well as a guideline which describes the interrelatio
7、nship of product noise levels and the resulting level in an installation. This ECMA TR/ summarizes acoustical terminology and describes the International Standards and regulations with regard to computer and business equipment. This ECMA nil also presents some examples of declared noise emission val
8、ues of computer and business equipment. Adopted as an ECMA Technical Report by the General Assembly of June 1993. Table of contents 1 scope 1 2 References 1 3 Acoustical terminology 3.1 General 3.2 The nature of sound 3.3 Ihe decibel scale 4 Glossary 4.1 4.2 Sound pressureip , in pascals Sound press
9、ure level, L, in decibels 4.2.1 Single machine 4.2.2 Adding sound pressure levels 4.3 4.4 4.5 4.6 4.7 4.8 4.9 Noise emission 4.10 4.11 Declared noise emission values Equivalent continuous sound pressure level, Lpq, in decibels A-weighted sound pressure level, Lp, in decibels C-weighted peak sound pr
10、essure level, L,cpit. in decibels Sound power, W, in warn The sound power level, Lw in decibels A-weighted sound power level, LWA. in decibels Emission sound power levei and sound pressure level 4.1 1.1 4.1 1.2 Declared sound power level, LWM. in bels Declared sound pressure levei, Lp. in decibels 4
11、.12 Noise immission 4.13 Rating sound level, L, in decibels 5 Noise emission versus noise immission 6 Product categories 6.1 General 6.2 Description of product categories 7 Product noise emission 7.1 7.2 7.3 7.4 Product noise emission specifications Declaration of product noise emission European pro
12、duct noise emission declaration requirement European requirement for work with display screen equipment 2 2 2 2 2 2 3 3 3 3 3 3 3 3 4 4 4 4 4 8 User environments 8.1 ManufacturingRJtility Area 9 10 - 11 - 8.2 Data Processing Area 8.3 General Business Area 8.4 Commercial (or Special) Office Area 8.5
13、Quit Office/Professional Office Area 9 Work station requirements Annex A Addition of noise levels Annex B Interrelationship Annex C Product noise emission declaration - Examples of noise emission declarations Annex D Product noise emission value for categories of computer and business equipment Anne
14、x E Recommended upper limits of declared sound power values 10 10 10 10 10 13 15 19 21 43 1 Scope ECMA TR/62 gives an overview of the latest developments in noise control standards and the interpretation of noise emission values of computer and business equipment. It describes the standardized quant
15、ities for the measurement and declaration of product noise emission of such equipment. This information may be useful when comparing the noise emission of equipment of the same product category as well as of different equipment used in the same environment. A comprehensive collection of product nois
16、e emission values for various categories of computer and business equipment is provided which supports such comparisons and helps in the interpretation of product noise emission. The applications of this Technical Report are in product design and announcement, product literature and data sheets as w
17、ell as in product selection for specific user requirements. It is not the purpose of this TR/62 to define product noise level specifications nor to establish noise exposure limits for persons working in the vicinity of computer and business equipment in a given environment. 2 References ECMA-74 ECMA
18、-108 ECMA-109 ECMA-160 ECMA TR/27 IS0 487 1 86/188/EEC 89/392/EEC 90/270/EEC Germany Sweden Measurement of Airborne Noise Emitted by Computer and Business Equipment Measurement of High Frequency Noise Emitted by Computer and Business Equipment Declared Noise Emission Values of Computer and Business
19、Equipment Determination of Sound Power Levels of Computer and Business Equipment Method for the Prediction of Installation Noise Levels Acoustics - Declaration and verification of noise emission values of machinery and equipment Council Directive of 12 May 1986 on the protection of workers from the
20、risks related to exposure to noise at work Council Directive of 14 June 1989 on the approximation of the laws of the Member States relating to machinery Council Directive of 29 May 1990 on the minimum safety and health requirements for work with display screen Arbeitsstattenverordnung, Par. 15 Liinn
21、 (workplace regulation, par. 15 noise) Statskontoret, The Swedish Agency for Administrative Development, Technical Standard 26:2 (1989-07-01), Noise of Computer and Business Equipment. NOTE 1 The interrelationship of ECMA and International, regional, and national standards is given in annex B. 3 Aco
22、ustical terminology 3.1 General In noise control a variety of terms and definitions have been introduced during the past two decades of standardization. When dealing with acoustical values a basic understanding of the most commonly used expressions is essential. These definitions are listed in claus
23、e 4 of this ECMA TR/. An important area of understanding relates to the distinction between the noise level emitted by an individual machine or a piece of equipment operated under well defined standard conditions in a controlled acoustical room (called EMISSION), and the noise which may occur at a r
24、eceivers location in a given environment under actual working conditions as a result of the influence of multiple noise sources, and to which individuals are exposed during their daily work (called IMMISSION). This interrelationship is explained in clause 5 of this ECMA TR/. The following descriptio
25、ns summarise some of the physical quantities which form the basis for noise measurements and noise ratings with regards to human hearing. -2- 33 The nature of sound Mechanically vibrating bodies put the surrounding air particles into movement which eventually reaches the human ear. For computer and
26、business equipment typical sound sources are printing mechanisms, moving paper, cooling devices, rotating disks, and transformers, which emit sound power ranging from about 18 watts to Air pressure fluctuations in the frequency range of 20 Hz to 2oooO Hz are perceived as sound. The sensitivity of th
27、e human ear is strongly frequency dependent at loo0 Hz it is sensitive to sound pressure fluctuations as low as 20 micromals, whereas at 100 Hz its sensitivity is reduced to 10 percent. It also perceives sound pressure fluctuations at about 20 pascals and above as painful. Because of this large rang
28、e of sensitivity of the human ear it is common practice to use a logarithmic scale when dealing with sound pressure fluctuations. The rating of sound pressure fluctuations on a logarithmic scale yields the sound pressure level in decibels, abbreviated dB, and is being a dimensionless quantity. ?he a
29、udible sound pressure fluctuations range from O dB to about 120 dB. A sound pressure level change of 1 dB may be just detected by the human ear, 3 dB are clearly perceived and 6 dB aresignificant. If a sound pressure level in increased by 10 dB, the ear normaily perceives it as a doubling in loudnes
30、s. A decrease of 10 dB is similarly perceived as a halving in loudness. NOTE 2 The decibel scale may be applied to both quantities, the total sound power emitted by a source, and the sound pressure, to which the human ear is sensitive. As this may easily lead to confusion, ECMA-109 reserves the deci
31、bel for sound pressure level measurement and declaration and uses the unit “bel“ ( 1 B = 10 dB) when declaring sound power levels. 10-2 watts. 33 The decibel scale 4 Glossary 4.1 4.2 4.2.1 4.2.2 4.3 Sound pressure, p , in pascals The sound pressure, p in pascals is the incremental variation in press
32、ure above and below the static pressure at a given location in air. Ihese variations are exhemely small; e.g. for normal speech, they average about 0,l pascals above and below atmospheric pressure at a distance of one metre from the speaker. For practical reasons the root- mean-square value (rms or
33、effective value) of the instantaneous sound pressures averaged over a time interval is determined. Sound pressure level, Lp, in decibels Single machine The sound pressure level, Lp in decibels is ten times the logarithm to the base 10 of the ratio of the square of the (rms) sound pressure, p, to the
34、 square of the reference sound pressure, po. of 20 micropascals ( po = 20 pa, the approximate threshold of hearing at lo00 Hz): P2 PO2 Lp = 10 Ig - dB Adding sound pressure levels In many practical situations the emitted noise of several machines may be combined to obtain a total level. A simple rul
35、e of thumb is: - Add two equal sources: The total value is 3 dB higher - Add ten equal sources: The total value is 10 dB higher A more detailed explanation is given in annex A. Equivalent continuous sound pressure level, LPq, in decibels The equivalent continuous sound pressure level, Lpq, in decibe
36、ls is equal to a steady sound pressure level which would produce the same sound energy over a stated period of time as a specified time-varying sound, also known as time-averaged sound pressure level. -3- 4.4 4.5 4.6 4.7 4.8 4.9 4.10 4.11 A-weighted sound pressure level, Lp, in decibels The A-weight
37、ed sound pressure level, Lp, in decibels is a frequency weighted (equivalent continuous) sound pressure level, where the standardized A-weighting accounts for the frequency dependent hearing characteristics. The A-weighted sound pressure level is the commonly used value for noise measurements and no
38、ise ratings with regard to its influence on man. The correct terminology is to express the value of LPA in decibels (dB) re 20 ph. although it is commonly expressed in units of dB(A) or dBA. C-weighted peak sound pressure level, Lpc, in decibels The C-weighted peak sound pressure level, LPcw in deci
39、bels is the highest instantaneous value of the C-weighted sound pressure level determined over an operationai cycle. Sound power, W, in watts The sound power, W, in watts is the rate per unit time at which airborne sound energy is radiated from a source into its environment. The sound power of a sou
40、rce is essentially independent of the environment. The sound power level, Lwin decibels The sound power level, Lw, in decibels is a logarithmic quantity of the measured sound power of a source with reference to i picowatt (Wo = i this level may include, or may be supplemented with corrections to acc
41、ount for the impulsive or tonal character of the rated noise. 4.13 5 Noise emission versus noise immission The interrelationship of the noise emitted by an individual machine, or several machines, (Product Noise Emission) and the noise perceived by an individual person at a given location in an inst
42、allation during a workshift (Noise Immission) is complex and must be determined for each situation individually. The procedure to determine the immission consists of a) predicting the installation noise level LpA from physical parameters such as room characteristics, declared noise emission values,
43、etc. Declared values jepend on the standard measurement procedure, standard instaliation conditions, sandard operations, and declaration procedure which takes into account measurement variability and production variation. b) determining actual LpAq by adjusting the predicted level to account for dif
44、ferences in actual equipment operation and exposure duration. c) determining the rating level L, by applying possible subjective corrections, if any, to the actual LpAq -5- These steps are shown in figure 1. ECMA TR/27 describes a method for predicting the Installation Noise level L Aq at a specifie
45、d work station for a given arrangement of equipment in a room with known acoustical properties, his predicted L Asq may be considered “typical“ for a specific location in a given installation. It considers the physical layout of tie installation and assumes standard operating conditions for the inst
46、alled equipment; it is free of subjective and variable parameters, but it may be used for immission predictions. These predictions are mainly useful when planning a new instaliation or for establishing a specification for a new product which is to be installed at work stations for which immission li
47、mits apply. The actual value of LpAq may differ from the predicted instaliation noise levei LpAq if the machines operate differently from standard condrtions and if the operators exposure duration is different. In an existing installation, a persons actual noise rating level Lr can be directly deter
48、mined from the equivalent continuous sound pressure level measured during a full workshift, usually using a noise dose meter which is attached to the workers clothing. Corrections for impulsive noise and/or prominent tones may be applied. Emission Immission Figure 1 - Interrelationship of noise emis
49、sion and noise immission 6 Product categories 6.1 General The evolution in the information technology industry during the past decade has provided a large variety of computer and business equipment being used in professional and private applications. There are product categories which are typidy found in a specific type of environment, e.g. text processing equipment in offices. On the other hand the same product family may be found in different working environments, e.g. table-top printers in General Business Areas as weil as in a Private office. For the purpose of this ECM
