BS EN ISO 3743-2:2009

1   Scope

   1.1   General 
   This part of [ISO 3743](/search?q=ISO%C2%A03743) 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](/search?q=ISO%C2%A03743%E2%80%911) are considerably less restric­ tive, it is recommended that the comparison method
     of [ISO 3743‑1](/search?q=ISO%C2%A03743%E2%80%911) be used if a special reverberation test room is not available. 
   
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