1、 Reference number ECMA-123:2009 Ecma International 2009 ECMA-109 6th Edition / December 2012 Declared Noise Emission Values of Information Technology and Telecommunications Equipment COPYRIGHT PROTECTED DOCUMENT Ecma International 2012 Ecma International 2012 i Contents Page 1 Scope 1 2 Normative re
2、ferences 2 3 Terms and definitions . 2 4 Conformance requirements 5 4.1 For declaration . 5 4.2 For verification . 5 5 Determination of the noise emission values to declare 5 5.1 General . 5 5.2 Determination of the sample mean A-weighted sound power level, AWL in decibels 5 5.3 Determination of the
3、 mean A-weighted sound power level, LWA,m in bels . 6 5.4 Determination of the mean A-weighted emission sound pressure level, LpA,m in decibels 6 5.5 Determination of the value to declare for the statistical adder for verification, Kv in bels 6 6 Presentation of declared noise emission values . 6 6.
4、1 Required information 6 6.2 Additional information 7 7 Verification of the statistical upper limit A-weighted sound power level, LWA,c 7 7.1 General . 7 7.2 Verification of LWA,c for a batch of equipment . 7 Annex A (normative) Procedure for determining the statistical adder for verification, Kv 9
5、Annex B (informative) Examples of noise emission declarations . 13 Annex C (informative) Character of noise 15 ii Ecma International 2012 Ecma International 2012 iii Introduction Information on acoustic noise emission of information technology and telecommunications equipment is needed by users, pla
6、nners, manufacturers and authorities. This information is required for comparison of the noise emissions from different products and for installation acoustics planning and may be used for relating to workplace noise immission requirements. In order for equipment noise emission data to be useful, un
7、iform methods are necessary for the following purposes: Measurement of noise emission values ECMA-74 specifies procedures for measuring sound power level based on ISO 37411, ISO 37442 and ISO 37453 (reverberation test room or hemi-anechoic room) and emission sound pressure level based on ISO 112015.
8、 Determination of the noise emission values to be declared ISO 4871 gives guidelines for the preparation of standards for deriving noise emission values for declaration purposes, and the ISO 7574 series gives statistical methods for such determination. ECMA-109 is based upon these basic Internationa
9、l Standards. Presentation of declared noise emission values For the presentation of declared noise emission values, it is of prime importance to declare A-weighted sound power levels, LWA. It is recognized, however, that users still desire information on A-weighted emission sound pressure levels, Lp
10、A. Therefore, this Ecma Standard specifies that both quantities shall be declared. In the preparation of this Ecma Standard divergences of opinion have been found between various national and international organisations as to the most useful way of presenting noise emission values. In order to avoid
11、 any misunderstanding between presentation of sound power levels in decibels re 1 pW and emission sound pressure levels in decibels re 20 Pa, this Ecma Standard expresses sound power level values to be declared in bels and emission sound pressure level values in decibels, to alleviate the divergence
12、s of opinion mentioned. As an option, methods for determination and presentation of subjective characteristics of noise emission are presented in annex C. Verification of declared noise emission values ISO 7574-4 gives methods for the verification of a declared noise emission value. In this Ecma Sta
13、ndard the procedure is restricted to verifying the statistical upper limit A-weighted sound power level, LWA,c only. The reasons for using bels for declared A-weighted sound power levels are: i) To avoid user confusion In this Ecma Standard the A-weighted sound power level is the primary descriptor
14、and will be reported in accordance with ISO 4871. Many manufacturers and users of information technology and telecommunications equipment have historically used A-weighted emission sound pressure levels in decibels. Since customers want both sound power and emission sound pressure levels, this Ecma
15、Standard utilises both quantities. Without including reference values (i.e. 1 pW and 20 Pa), expressing both declared sound power levels and declared emission sound pressure levels in decibels tends to cause confusion. To distinguish the two, this Ecma Standard expresses declared sound power level i
16、v Ecma International 2012 values in bels, where a bel is 10 decibels re 1pW, and expresses emission sound pressure level values in decibels re 20 Pa. ii) To avoid misapplication of data If declared A-weighted sound power levels were expressed in decibels, users may mistakenly compare the sound power
17、 levels with workplace regulations of immission sound pressure levels. In many information technology and telecommunications equipment applications, the sound power level (in decibels) value of the equipment is significantly larger than the immission sound pressure level (in decibels) value measurab
18、le in the workplace. The later, immission value is the level at human ear location in a given environment which changes with the acoustic environment, such as room size, acoustical attenuation property of floor, wall, ceiling, doors, windows and room partitions, etc. while the sound power level valu
19、e is an intrinsic property of equipment that does not change with the environment it is placed in. iii) To promote the use of ECMA-109 The purpose of ECMA-109 is to provide uniform methods of presenting declared noise emission values to users. Without using bels, this objective would be lost since t
20、here would be an incentive for some manufacturers to report emission sound pressure levels instead of sound power levels. The primary descriptor of information technology and telecommunications equipment noise is the declared mean A-weighted sound power level, LWA,m. If ECMA-109 were to use decibels
21、 for declared A-weighted sound power levels, manufacturers who do not implement this Ecma Standard would be at a competitive advantage by reporting emission sound pressure levels in decibels which would be lower than the declared sound power levels also in decibels. Not only would the user be confus
22、ed, and unable to tell the difference, but the manufacturer who followed ECMA-109 would be at an unfair competitive disadvantage. To eliminate this confusion and disadvantage and to promote the uniform reporting of declared noise emission values, the declared A-weighted sound power levels must be re
23、ported in bels. iv) To use a method based on successful experience For several years, many international companies, members of Ecma, have reported A-weighted sound power levels in bels and A-weighted emission sound pressure levels in decibels without confusion of their customers. Indeed, their custo
24、mers have been able to distinguish easily between the important difference of sound power level and emission sound pressure level, and the users have not lost the significance of the digit after the decimal mark. Actually they have been less confused: without using bels, they would wonder: “which de
25、cibel do I compare to our specification?“. v) To be consistent with other Ecma and ISO standards The use of bels for declared A-weighted sound power levels is consistent with ISO 4871 “Acoustics Declaration and verification of noise emission values of machinery and equipment“ and with ISO 7574-1 “Ac
26、oustics Statistical methods for determining and verifying stated noise emission values of machinery and equipment Part 1: General considerations and definitions“. The statistical upper limit A-weighted sound power level, LWA,c, is a statistical upper limit value and corresponds to the “declared sing
27、le-number noise emission value“ in ISO 4871 and “labelled value“ in ISO 7574-1. The definition of “declared single-number noise emission value “ in ISO 4871 and “labelled value“ in ISO 7574-1 has a note which states that in some cases, the labelled value may be expressed as the numerical value of so
28、und power level in decibels divided by 10, given with one digit after the decimal mark, i.e. in bels. ECMA-109 recognizes that the sound power is determined in decibels, in accordance with either ECMA-74 which is based upon ISO 3741, ISO 3744 or ISO 3745, and is then reported to the customers as a d
29、eclared value in bels. The first edition of Standard ECMA-109 was processed by ISO under the fast-track procedure and led to International Standard ISO 92964. The second edition has been adapted to the final wording of ISO 9296. The third edition was adapted to allow for the determination of declare
30、d sound power level based on measurements made in accordance with ECMA-1606 (using sound intensity) as an alternative to ECMA-74 (reverberation test room or hemi-anechoic room). Ecma International 2012 v The fourth edition corrected minor errors in the third edition, including re-arrangements of the
31、 text, and clarified the procedure when only a single machine from a batch has been measured and there is no prior knowledge of the standard deviation of production. The fifth edition changed Annex A to be normative rather than informative, and added an additional quantity to the declared value when
32、 the mean value is based on five or fewer units8. It also removed the single equipment sound power level declaration clause due to statistical concerns. In addition, descriptions related to ECMA-160 were removed to align with sound power determination in accordance with ECMA-74. This sixth edition c
33、hanges the focus of the declaration to be the mean sound power level rather than the statistical upper limit. In order to maintain compatibility with existing purchasing specifications, eco labels, and other standards which reference the statistical upper limit, all information needed to calculate t
34、he upper limit is required in the declaration. The additional guard band for declarations based on small sample sizes added in the fifth edition is changed to being informative rather than normative. This Ecma Standard has been adopted by the General Assembly of December 2012. vi Ecma International
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41、BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY OWNERSHIP RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.“ Ecma International 2012 1 Declared Noise Emission Values of Information Technology and Telecommunications E
42、quipment 1 Scope This Ecma Standard applies to information technology and telecommunications equipment. This Ecma Standard specifies: the method for determining the mean A-weighted sound power level, LWA,m for a batch of machines, the method for determining the mean A-weighted emission sound pressur
43、e level, LpA,m for a batch of machines, the method for determining the statistical adder for verification, Kv for a batch of machines, the method for determining the statistical upper limit A-weighted sound power level, LWA,c for a batch of machines to be used for verification, acoustical and produc
44、t information to be published electronically or in hard-copy format in technical documents or other product literature supplied to users by the manufacturer, and the method for verifying the noise emission values that are published or stated by the manufacturers and other product suppliers. The unif
45、orm methods in this Ecma Standard use the noise emission data obtained in accordance with ECMA-74, and the procedures specified in ISO 4871 and ISO 7574-4. The basic noise emission values to be declared or stated are the mean A-weighted sound power level, LWA,m and the mean A-weighted emission sound
46、 pressure level at the operator or bystander positions, LpA,m. These are arithmetic mean values based upon measurements on a sample of machines in accordance with ECMA-74. For verification purposes, an additional quantity is required to be stated or declared: the so-called statistical adder for veri
47、fication. This is a factor that is added to the mean A-weighted sound power level and used in the verification section of this Standard to provide a consistent and predictable probability of acceptance for the batch of equipment. The mean A-weighted sound power level for the batch of machines permit
48、s comparison of noise emissions between different products and permits predictions of installation or work-place noise immission levels, as described in ECMA TR/277. Although the most useful quantity for calculating immission levels due to one or more sound sources is the A-weighted sound power leve
49、l of the individual source(s), the A-weighted emission sound pressure level may also be useful in estimating the immission level in the immediate vicinity of an isolated piece of equipment. To avoid confusion between sound power levels and emission sound pressure levels, the mean A-weighted sound power level, LWA,m is stated in bels (B) and the A-weighted emission sound pressure level, LpA,m is stated in decibels (dB). 2 Ecma International 2012 2 Normative references The following referenced documents are indispensable for the
