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Standard ECMA-109
Declared Noise Emission Values of Information Technology and Telecommunications Equipment

4^th edition (December 1996)

This Standard applies to computer and business equipment.

This Standard specifies:

The uniform methods in this Standard use the noise data obtained in accordance with Standard ECMA-74 or Standard ECMA-160, and the procedures specifies in ISO 4871 and ISO 7574

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 ) and the declared A-weighted 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 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 sound pressure levels, the A-weighted sound power level value is declared in bels an the A-weighted sound power level is declared in decibels.

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This Ecma publication is also approved as ISO 9296.

The previous replaced "historial" editions of this Ecma standard are available here.

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