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Laboratory studies of scales for measuring helicopter noiseThe adequacy of the effective perceived noise level (EPNL) procedure for rating helicopter noise annoyance was investigated. Recordings of 89 helicopters and 30 fixed wing aircraft (CTOL) flyover sounds were rated with respect to annoyance by groups of approximately 40 subjects. The average annoyance scores were transformed to annoyance levels defined as the equally annoying sound levels of a fixed reference sound. The sound levels of the test sounds were measured on various scales, with and without corrections for duration, tones, and impulsiveness. On average, the helicopter sounds were judged equally annoying to CTOL sounds when their duration corrected levels are approximately 2 dB higher. Multiple regression analysis indicated that, provided the helicopter/CTOL difference of about 2 dB is taken into account, the particular linear combination of level, duration, and tone corrections inherent in EPNL is close to optimum. The results reveal no general requirement for special EPNL correction terms to penalize helicopter sounds which are particularly impulsive; impulsiveness causes spectral and temporal changes which themselves adequately amplify conventionally measured sound levels.
Document ID
Document Type
Contractor Report (CR)
Ollerhead, J. B. (Wyle Labs., Inc. El Segundo, CA, United States)
Date Acquired
September 4, 2013
Publication Date
November 1, 1982
Subject Category
Report/Patent Number
NAS 1.26:3610
Funding Number(s)
Distribution Limits
Work of the US Gov. Public Use Permitted.

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NameType 19830003569.pdf STI