1 Scope
1.1 General
This part of ISO 3743 specifies a relatively simple en gineering method for determining the sound power
levels of small, movable noise sources. The measurements are carried out when the
source is in stalled in a specially designed room having a specified reverberation
time over the frequency range of interest. The A-weighted sound power level of the
source under test is determined from a single A weighted sound pressure level measurement
at each microphone position, rather than from a summation of octave-band levels. This
direct method eliminates the need for a reference sound source, but requires the use
of a special reverberation test room. The direct method is based on the premise that
the sound pressure level, averaged in space and time in the test room, can be used
to determine the sound power level emitted by the source. The properties of the special
reverberation test room are chosen so that the room's influence on the sound power
output of the equipment under test is small. The number of micro phone positions
and source locations required in the test room are specified. Guidelines for the design
of special reverberation rooms are given in annex B.
In addition to the direct method, a comparison method is also described (see 8.3). However, since the requirements on the test room for the comparison method of ISO 3743‑1 are considerably less restric tive, it is recommended that the comparison method
of ISO 3743‑1 be used if a special reverberation test room is not available.