Robert G. Gibson
Wyle Labs., 2001 Jefferson Davis Hwy., Ste. 701, Arlington, VA 22202
Low-frequency noise emission from facilities designed for the ground runup
testing of jet engines can be a source of annoyance to communities near
military air bases. Noise measurements, using arrays of microphones and
accelerometers at a number of U.S. Air Force hush houses, provide information
regarding the source characteristics. Comparisons are made between noise from a
single aircraft both inside and outside a hush house. Source location
calculations indicate that low-frequency noise originates from a region near
the trailing edge of the jet exhaust deflector. Coherence between selected
near-field and far-field sensors is found to be sufficiently high to warrant
experimental investigation of the active reduction of noise from a full scale
hush house, using feedforward control techniques, following on from the small
scale hush house experiments described by J. P. Smith et al. [