DI-HFAC-81981
m. Acoustical environment (outdoor). When testing outdoors, the following shall be
included:
(1) Location and orientation of test unit relative to buildings, structures, and other
reflecting surfaces and objects.
(2) Description of the ground surface, and wind direction and speed.
3.3. Measured data. This section shall contain:
a. Measured data in reference units that are identical to the specified reference units.
b. Any measurements that are included in graphical form shall show ordinate (magnitude)
values with 10 dB between major divisions.
c. Measured data, by measurement location and orientation, with accompanying
information at that same location including background and ambient data and assigned
limits.
d. For airborne noise levels that exceed the specified limits, excesses shall be clearly
indicated in any tabulated and plotted data.
e. If excesses to the specified octave band airborne levels are included in graphical form,
plots of narrowband data measured at the offending microphone positions, with
frequency resolution not to exceed 1 Hz, shall be included.
f. The mechanisms that exist within the machinery and equipment that are specifically
responsible for the measured excesses (e.g., rotational frequency, blade, vane and piston
frequency, firing frequency, gear mesh frequency, coincidence of a forcing frequency
with a natural frequency of the mounting system, resonance in the subbase).
End of DI-HFAC-81981
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