scope:

This standard applies to all machinery and equipment that is essentially stationary in nature and for which overall A-weighted sound power is a meaningful descriptor of noise emission. It is not applicable to machines or equipment that radiate most of their sound into ducts and piping systems and which must be tested in conjunction with the appropriate duct or piping system. It does not provide the spectral information needed for noise control design decisions.

This standard is intended to be used in conjunction with American and International Standards that describe alternative methods for determining the sound power level and with such additional test codes or standards as are needed to define the test and operating conditions appropriate to the noise radiation properties of specific types of machines or equipment. The designation described in this standard is based on the A-weighted sound power emitted by the source. The directional characteristics of the source are not included in the designation. This method is applicable only when the A-weighted sound power level can be obtained directly or indirectly using one of the procedures described in American or International Standards.

PURPOSE

It is the purpose of this standard to describe a method for expressing the noise emissions of machinery and equipment in a convenient manner. The method may be useful for equipment specification, labeling, or other documentation that expresses in quantitative terms the noise emission of a product or device. It is not the purpose of this standard to provide a classification of noise sources. The primary purpose of this standard is to define a standard noise descriptor, i.e., the noise emission level in bels, to facilitate the reporting of A-weighted sound power levels of machinery and equipment.

For some small sound sources, it may be convenient to provide also a single number rating in terms of free field sound level (A-weighted sound pressure level) at a specific distance. A method for obtaining such a sound pressure level rating from the sound power level designation is described in Appendix A.