Author: Sherman A. ClevensonPublisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 32
Book Description
A laboratory study was conducted to determine the effects of helicopter interior noise on passenger annoyance. Bothe reverie and listening situations were studied as well as the relative effectiveness of several descriptors (i.e., overall sound pressure level, A-weighted sound pressure level, and speech interference level) for quantifying annoyance response for these situations. The noise stimuli were based upon recordings of the interior noise of the NASA Civil Helicopter Research Aircraft. These noises were presented at levels ranging from approximately 68 to 86 dB(A) with various gear clash tones selectively attenuated to give a range of spectra. The listening tasks required the subjects to listen to and record phonetically balanced words presented within the various noise environments. Results indicate that annoyance during a listening condition is generally higher than annoyance during a reverie condition for corresponding interior noise environments. Attenuation of the planetary gear clash tone results in increases in listening performance but has negligible effect upon annoyance for a given noise level. The noise descriptor most effective for estimating annoyance response under conditions of reverie and listening situations is shown to be the A-weighted sound pressure level. (Author).