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Evaluation of the annoyance due to helicopter rotor noiseA program was conducted in which 25 test subjects adjusted the levels of various helicopter rotor spectra until the combination of the harmonic noise and a broadband background noise was judged equally annoying as a higher level of the same broadband noise spectrum. The subjective measure of added harmonic noise was equated to the difference in the two levels of broadband noise. The test participants also made subjective evaluations of the rotor noise signatures which they created. The test stimuli consisted of three degrees of rotor impulsiveness, each presented at four blade passage rates. Each of these 12 harmonic sounds was combined with three broadband spectra and was adjusted to match the annoyance of three different sound pressure levels of broadband noise. Analysis of variance indicated that the important variables were level and impulsiveness. Regression analyses indicated that inclusion of crest factor improved correlation between the subjective measures and various objective or physical measures.
Document ID
19780016960
Document Type
Contractor Report (CR)
Authors
Sternfeld, H., Jr. (Boeing Vertol Co. Philadelphia, PA, United States)
Doyle, L. B. (Boeing Vertol Co. Philadelphia, PA, United States)
Date Acquired
September 3, 2013
Publication Date
June 1, 1978
Subject Category
ACOUSTICS
Report/Patent Number
NASA-CR-3001
Funding Number(s)
CONTRACT_GRANT: NAS1-14192
PROJECT: RTOP 505-09-13-11
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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