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Evaluation of the impact of noise metrics on tiltrotor aircraft design
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Author and Affiliation:
Sternfeld, H.(Boeing Defense and Space Group, Philadelphia, PA, United States);
Spencer, R.(Boeing Defense and Space Group, Philadelphia, PA, United States);
Ziegenbein, P.(Boeing Defense and Space Group, Philadelphia, PA, United States)
Abstract: A subjective noise evaluation was conducted in which the test participants evaluated the annoyance of simulated sounds representative of future civil tiltrotor aircraft. The subjective responses were correlated with the noise metrics of A-weighted sound pressure level, overall sound pressure level, and perceived level. The results indicated that correlation between subjective response and A-weighted sound pressure level is considerably enhanced by combining it in a multiple regression with overall sound pressure level. As a single metric, perceived level correlated better than A-weighted sound pressure level due to greater emphasis on low frequency noise components. This latter finding was especially true for indoor noise where the mid and high frequency noise components are attenuated by typical building structure. Using the results of the subjective noise evaluation, the impact on tiltrotor aircraft design was also evaluated. While A-weighted sound pressure level can be reduced by reduction in tip speed, an increase in number of rotor blades is required to achieve significant reduction of low frequency noise as measured by overall sound pressure level. Additional research, however, is required to achieve comparable reductions in impulsive noise due to blade-vortex interaction, and also to achieve reduction in broad band noise.
Publication Date: Nov 01, 1995
Document ID:
19960009107
(Acquired Feb 06, 1996)
Accession Number: 96N16273
Subject Category: ACOUSTICS
Report/Patent Number: NASA-CR-198240, NAS 1.26:198240, NIPS-95-06842
Coverage: Final Report
Document Type: Technical Report
Publisher Information: United States
Contract/Grant/Task Num: NAS1-20095; RTOP 538-07-15-10
Financial Sponsor: NASA; United States
Organization Source: Boeing Defense and Space Group; Helicopters Div.; Philadelphia, PA, United States
Description: 39p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: No Copyright
NASA Terms: AIRCRAFT DESIGN; AUDITORY PERCEPTION; BLADE-VORTEX INTERACTION; CIVIL AVIATION; NOISE INTENSITY; NOISE REDUCTION; PSYCHOACOUSTICS; SOUND PRESSURE; TILT ROTOR AIRCRAFT
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