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Advanced turboprop aircraft flyover noise: Annoyance to counter-rotating-propeller configurations with a different number of blades on each rotor: Preliminary resultsA laboratory experiment was conducted to quantify the annoyance of people to the flyover noise of advanced turboprop aircraft with counter-rotating propellers (CRP) having a different number of blades on each rotor (nxm, e.g., 10 x 8, 12 x 11). The objectives were: (1) compare annoyance to nxm CRP advanced turboprop aircraft with annoyance to conventional turboprop and jet aircraft; (2) determine the effects of tonal content on annoyance; and (3) determine the ability of aircraft noise measurement procedures and corrections to predict annoyance for this new class of aircraft. A computer synthesis system was used to generate 35 realistic, time-varying simulations of advanced turboprop takeoff noise in which the tonal content was systematically varied to represent combinations of 15 fundamental frequency (blade passage frequency) combinations and three tone-to-broadband noise ratios. The fundamental frequencies, which represented blade number combinations from 6 x 5 to 13 x 12 and 7 x 5 to 13 x 11, ranged from 112.5 to 292.5 Hz. The three tone-to-broadband noise ratios were 0, 15, and 30 dB. These advanced turboprop simulations along with recordings of five conventional turboprop takeoffs and five conventional jet takeoffs were presented at D-weighted sound pressure levels of 70, 80, and 90 dB to 64 subjects in an anechoic chamber. Analyses of the subjects' annoyance judgments compare the three categories of aircraft and examine the effects of the differences in tonal content among the advanced turboprop noises. The annoyance prediction ability of various noise measurement procedures and corrections is also examined.
Document ID
19890015517
Acquisition Source
Legacy CDMS
Document Type
Technical Memorandum (TM)
Authors
Mccurdy, David A. (NASA Langley Research Center Hampton, VA, United States)
Date Acquired
September 5, 2013
Publication Date
July 1, 1988
Subject Category
Acoustics
Report/Patent Number
NAS 1.15:100638
NASA-TM-100638
Accession Number
89N24888
Funding Number(s)
PROJECT: RTOP 535-03-11-03
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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