The reverberant field level in an equipment room with all existing machinery running is 82 dB(A)….

The reverberant field level in an equipment room with all existing machinery running is 82
dB(A). Three additional machines are to be installed and precautions are to be taken to ensure
that the resulting new reverberant field level does not exceed 85 dB(A). Proceed as follows:
(a) Calibrate a reference noise source outside the plant in an empty asphalt car park. The
average sound pressure level at 3 m is determined to be 75 dB(A). What is the A weighted sound power level of the reference sound source?
(b) With the reference source turned on and on the concrete floor in the equipment room,

»The reverberant field level in an equipment room with all existing machinery running is 82
dB(A). Three additional machines are to be installed and precautions are to be taken to ensure
that the resulting new reverberant field level does not exceed 85 dB(A). Proceed as follows:
(a) Calibrate a reference noise source outside the plant in an empty asphalt car park. The
average sound pressure level at 3 m is determined to be 75 dB(A). What is the A weighted sound power level of the reference sound source?
(b) With the reference source turned on and on the concrete floor in the equipment room,
and with the room machinery turned off, the reverberant field level is 87 dB(A). What
is the sound power level of the existing machinery?
(c) What is the maximum sound power the three new machines together may produce?
(d) If the sound from each of the three new machines may be expected to be about equal,
what is the upper bound on the A-weighted source power level of each which will allow
the objective given above to be met?

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