TM 5-805-4/AFJMAN 32-1090
Table 9-1. Sample Sound Pressure Level Specification
The maximun sound pressure levels measured at a distance of 3 ft. from the
1.
(equipment in question) shall not exceed the following decibel values
in the nine octave frequency bands:
Sound Pressure
Octave
Band
Level
(dB re 20 micropascals)
(Hz)
31
(Insert desired
63
sound pressure
levels in blanks)
125
250
500
1000
2000
4000
8000
At least four sets of sound pressure level readinqs shall be submitted
2.
with the bid, where each set is taken at a 3-ft. distance from each of
the four principal orthogonal surfaces of the equipment. Each octave
band reading of each set of readings shall be no greater than the speci-
fied value of Item 1 above.
The test room in which the noise measurements are conducted shall have a
3.
volume of not less than 4000 ft.3 and all principal surface areas of
the room shall be described in sufficient acoustic detail to permit an
estimation of the approximate Room Constant or Room Absorption for the
space.
During the tests, the equipment shall be in normal operation at not less
4.
than 50% full rated load (or at a specified mutually acceptable load'
The tests shall be carried out by the equipment manufacturer
condition).
or by an approved testing agency, having proven capability in noise
measurements and using approved measurement equipment and acceptable
measurement procedures. Approved "standards" of measurements shall apply.
In lieu of the tests under Item 4 above, final testing for conformance
5.
with the Item 1 noise levels may be made following complete installation
of the equipment in the customer's building, provided the equipment manu-
facturer will remove and replace the equipment at his own expense if it
fails to meet the noise tests. To be acceptable, the replacement equipment
must meet the noise tests. For the on-site tests, the equipment shall be
in normal operation at not less than 50% hill rated load (or at a specified
mutually acceptable load condition), and the tests shall be in accordance
with the procedures given in Item 4 above.
For all noise tests, the ambient sound levels of the test area shall be
6.
at least 10 dB below the specified levels of Item 1 above, and the
octave band sound measurement equipment shall meet the applicable ANSI
standards for that type of equipment.
9-3
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