This American National Standard specifies procedures formeasuring and reporting the noise emission of informationtechnology and telecommunications equipment. This Standard isconsidered part of a noise test code for this type of equipment andis based on basic noise emission standards ANSI/ASA S12.51 / ISO3741, ANSI/ASA S12.54 / ISO 3744, ANSI/ASA S12.55 / ISO 3745 andISO 11201. The basic emission quantity is the A-weighted soundpower level which may be used for comparing equipment of the sametype but from different manufacturers, or for comparing differentequipment.
Three basic noise emission standards for determining the soundpower levels are specified in this American National Standard inorder to avoid undue restriction on existing facilities andexperience. The first basic standard (ANSI/ASA S12.51 / ISO 3741)specifies comparison measurements in a reverberation test room; theother two (ANSI/ASA S12.54 / ISO 3744 and ANSI/ASA S12.55 / ISO3745) specify measurements in an essentially free field over areflecting plane. Any one of these three basic noise emissionstandards may be selected and shall then be used exclusivelyaccording to this Standard when determining sound power levels of amachine.
The A-weighted sound power level is supplemented by theA-weighted emission sound pressure level determined at the operatorposition(s) or the bystander positions, based on the basic noiseemission standard ISO 11201. This sound pressure level is not aworker's immission rating level, but it may assist in identifyingany potential problems that could cause annoyance, activityinterference, or hearing damage to operators and bystanders.
Methods for determining whether the noise emission includesprominent discrete tones or is impulsive in character are specifiedin Annexes D and E, respectively.
This Standard is suitable for type tests and provides methodsfor manufacturers and testing laboratories to obtain comparableresults.
The methods specified in this Standard allow the determinationof noise emission levels for a unit tested individually.
The procedures may be applied to equipment which emitsbroad-band noise, narrow-band noise and noise which containsdiscrete-frequency components, or impulsive noise.
The sound power and emission sound pressure levels obtained mayserve noise emission declaration and comparison purposes (seeECMA-109). They are not to be considered as installation noiseimmission levels; however, they may be used for installationplanning (see ECMA TR/27).
If sound power levels obtained are determined for a number ofunits of the same production series, they can be used to determinea statistical value for that production series (see ECMA-109).