ECMA - 109
Declared Noise Emission Values of Information Technology and Telecommunications Equipment
|Publication Date:||1 December 2010|
This Ecma Standard applies to information technology and telecommunications equipment.
This Ecma Standard specifies:
• the method of determining the declared noise emission values of a batch of machines,
• acoustical and product information to be given in technical documents supplied to users by the manufacturer,
• the method for verifying the declared noise emission values given by the manufacturers.
The uniform methods in this Ecma Standard use the noise emission data obtained in accordance with ECMA-74, and the procedures specified in ISO 4871  and the ISO 7574 series.
The basic declared noise emission values are the declared A-weighted sound power level LWAd (a statistical maximum value corresponding to Lc in ISO 7574-1) and the declared A-weighted emission sound pressure level LpAm (a mean value) at the operator or bystander positions.
The declared A-weighted sound power level LWAd permits comparison of noise emissions between different products and permits predictions of installation or work-place noise immission levels, as described in ECMA TR/27 .
Although the most useful quantity for calculating immission levels due to one or more sound sources is usually the declared A-weighted sound power level of the individual source(s), the declared A-weighted emission sound pressure level LpAm may be used to estimate 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 A-weighted sound power level is declared in bels and the A-weighted emission sound pressure level is declared in decibels.