DNV 109

This Ecma Standard applies to information technology andtelecommunications equipment.

This Ecma Standard specifies:

• the method for determining the mean A-weighted sound powerlevel, L_WA,m for a batch of machines,

• the method for determining the mean A-weighted emission soundpressure level, L_pA,m for a batch ofmachines,

• the method for determining the statistical adder forverification, K_v for a batch of machines,

• the method for determining the statistical upper limitA-weighted sound power level, LWA,c for a batch of machines to beused for verification,

• acoustical and product information to be publishedelectronically or in hard-copy format in technical documents orother product literature supplied to users by the manufacturer,and

• the method for verifying the noise emission values that arepublished or stated by the manufacturers and other productsuppliers.

The uniform methods in this Ecma Standard use the noise emissiondata obtained in accordance with ECMA-74, and the proceduresspecified in ISO 4871 and ISO 7574-4.

The basic noise emission values to be declared or stated are themean A-weighted sound power level, LWA,m and the mean A-weightedemission sound pressure level at the operator or bystanderpositions, L_pA,m. These are arithmetic meanvalues based upon measurements on a sample of machines inaccordance with ECMA-74.

For verification purposes, an additional quantity is required tobe stated or declared: the so-called statistical adder forverification. This is a factor that is added to the mean A-weightedsound power level and used in the verification section of thisStandard to provide a consistent and predictable probability ofacceptance for the batch of equipment.

The mean A-weighted sound power level for the batch of machinespermits comparison of noise emissions between different productsand permits predictions of installation or work-place noiseimmission levels, as described in ECMA TR/27.

Although the most useful quantity for calculating immissionlevels due to one or more sound sources is the A-weighted soundpower level of the individual source(s), the A-weighted emissionsound pressure level may also be useful in estimating the immissionlevel in the immediate vicinity of an isolated piece ofequipment.

To avoid confusion between sound power levels and emission soundpressure levels, the mean A-weighted sound power level,L_WA,m is stated in bels (B) and the A-weightedemission sound pressure level, LpA,m is stated in decibels(dB).

Edition:

6

Published:

12/01/2012

Number of Pages:

26