### ASA 127th Meeting M.I.T. 1994 June 6-10

## 4pSAa9. Statistical energy analysis prediction of the interior
low-frequency noise for a propeller-driven aircraft.

**Jerome E. Manning
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*Cambridge Collaborative, Inc., 689 Concord Ave., Cambridge, MA 02138
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Statistical energy analysis (SEA) is generally used to predict acoustic
environments at high frequencies for random excitations. SEA can also be used
to predict the environment at low frequencies for pure-tone excitations. The
use of SEA for such problems requires consideration of both the mean and
variance of the statistical prediction. Assuming a normal distribution of
acoustic levels, 95% of measured data would be expected to fall within the
limits set by the mean plus and minus two times the standard deviation. The use
of SEA to predict both the mean and standard deviation of the cabin noise for a
propeller-driven aircraft will be shown and comparisons with measured data will
be presented. Methods to reduce the predicted variance will be discussed.