ASA - ANSI/ASA S12.2
American National Standard Criteria for Evaluating Room Noise
| Organization: | ASA |
| Publication Date: | 3 July 2008 |
| Status: | inactive |
| Page Count: | 50 |
scope:
This Standard provides three primary methods for evaluating room noise: a survey method, an engineering method, and a method for evaluating low-frequency fluctuating noise. Two methods for evaluating room noise-RC (room criterion) and NCB (balanced noise criterion) curves-were the basis of the previous ANSI S12.2-1995 standard, and RC is included briefly for informational purposes in Annex D. All of the methods assume that the measured noise is free of tones. (ANSI S1.13-2005 Annex A gives an accurate method for assessing the presence of prominent discrete tones using narrow band analysis.)
The three primary methods are:
1. The survey method that employs the A-weighted sound level;
2. The engineering method that employs noise criteria (NC) curves; and
3. The method for evaluating low-frequency fluctuating noise using room noise criteria (RNC) curves.
This Standard also contains one ancillary set of criteria curves for evaluating acoustically induced vibrations or rattles.
Requirements are given in the body of the Standard for determining whether a:
1. Measured or estimated A-weighted sound level satisfies a specified noise criterion.
2. Set of octave-band sound pressure levels satisfies a specified noise criterion (NC) curve.
3. Time-series of octave-band sound pressure levels satisfies a specified room noise criterion (RNC) curve.
4. Table of octave-band sound pressure levels that, when modulated by fluctuations at low frequencies, may cause perceptible vibrations or rattles in lightweight constructions.
Annex A presents examples of the use of RNC for evaluating measured or estimated sound level spectra in rooms.
Annex B presents a discussion of RC, NC, NCB, and RNC curves.
Annex C contains recommended noise level specifications for various occupied activity areas.
Annex D contains the procedures for use of the room criteria (RC) curves.
Annex E contains criteria for recording studios and other low-noise situations.
No guidance is given for the selection of equipment or the methods for measuring noise levels to be evaluated by the curves.
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