scope:

The three primary methods for evaluating room noise 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 NC curve.

3. Time-series of octave-band sound pressure levels satisfies a specified 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 room criteria (RC), NC, balanced noise criteria (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 RC Mark II 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.