1. Scope

1.1

This Recommended Practice describes a procedure for the prediction of sound pressure levels in a large room containing a number of sound sources. This procedure may be used to compute A-weighted, octave, or fractional octave band sound pressure levels over continuous contours, or at specific points, to predict:

(a) Sound pressure levels at the design stage;

(b) The effect of altering or moving equipment in an existing space; and

(c) The effect of changing the acoustical environment.

1.2

The use of the procedure described in this Recommended Practice requires that the sound emitted from each source (preferably measured in accordance with CSA Standard Z107.51, Procedure for In-Situ Measurement of Noise From Industrial Equipment) be known. When this procedure is used to predict the effect of installing or removing one or more machines, it is sufficient to know the sound pressure levels in the existing space, as well as the sound power levels of each machine.

1.3

This Recommended Practice applies to rectangular rooms with a relatively constant height. The length and width of the room should each be greater than about 4 times the height. Where the roo m geometry departs materially from the simple rectangular shape, the prediction given by this procedure may be incorrect.

1.4

This Recommended Practice can be used with the knowledge of the length of time spent by workers at various locations to estimate the ir sound exposure.

1.5

This Recommended Practice does not apply to:

(a) The prediction of the sound pressure levels resulting from the introduction of large sources, objectives, or barriers at distances less than four times their largest dimension;

(b) The prediction of impulse sound levels;

(c) The prediction of sound pressure levels if a highly directive noise source is added; and

(d) The prediction of sound pressure levels if a noise source has a predominate pure tone.