ASA - ANSI/ASA S12.56/ISO 3746
AMERICAN NATIONAL STANDARD Acoustics – Determination of sound power levels and sound energy levels of noise sources using sound pressure – Survey method using an enveloping measurement surface over a reflecting plane (a Nationally Adopted International Standard)
| Organization: | ASA |
| Publication Date: | 28 June 2011 |
| Status: | active |
| Page Count: | 68 |
scope:
General
This American National Standard specifies methods for determining the sound power level or sound energy level of a noise source from sound pressure levels measured on a surface enveloping a noise source (machinery or equipment) in a test environment for which requirements are given. The sound power level (or, in the case of noise bursts or transient noise emission, the sound energy level) produced by the noise source with frequency A-weighting applied is calculated using those measurements.
NOTE Differently shaped measurement surfaces can yield differing estimates of the sound power level of a given noise source and an appropriately drafted test code (see ISO 12001) gives detailed information on the selection of the surface.
Types of noise and noise sources
The methods specified in this American National Standard are suitable for all types of noise (steady, non-steady, fluctuating, isolated bursts of sound energy, etc.) defined in ISO 12001.
This American National Standard is applicable to all types and sizes of noise source (e.g. stationary or slowly moving plant, installation, machine, component or sub-assembly), provided the conditions for the measurements can be met.
NOTE The conditions for measurements given in this American National Standard can be impracticable for very tall or very long sources such as chimneys, ducts, conveyors, and multi-source industrial plants. A test code for the determination of noise emission of specific sources can provide alternative methods in such cases.
Test environment
The test environments that are applicable for measurements made in accordance with this American National Standard can be located indoors or outdoors, with one or more sound-reflecting planes present on or near which the noise source under test is mounted.
Measurement uncertainty
Information is given on the uncertainty of the sound power levels and sound energy levels determined in accordance with this American National Standard, for measurements made with frequency A-weighting applied. The uncertainty conforms with that of ISO 12001:1996, accuracy grade 3 (survey grade).
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