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Analysis of ground reflection of jet noise obtained with various microphone arrays over an asphalt surfaceGround reflection effects on the propagation of jet noise over an asphalt surface are discussed for data obtained using a 33.02 cm (13-in.) diameter nozzle with microphones at several heights and distances from the nozzle axis. Analysis of ground reflection effects is accomplished using the concept of a reflected signal transfer function which represents the influence of both the reflecting surface and the atmosphere on the propagation of the reflected signal in a mathematical model. The mathematical model used as a basis for the computer program was successful in significantly reducing the ground reflection effects. The range of values of the single complex number used to define the reflected signal transfer function was larger than expected when determined only by the asphalt surface. This may indicate that the atmosphere is affecting the propagation of the reflected signal more than the asphalt surface. Also discussed is the selective placement of the reinforcements and cancellations in the design of an experiment to minimize ground reflection effects.
Document ID
19750058639
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Miles, J. H.
(NASA Lewis Research Center Cleveland, Ohio, United States)
Date Acquired
August 8, 2013
Publication Date
April 1, 1975
Subject Category
Acoustics
Meeting Information
Meeting: Acoustical Society of America, Meeting
Location: Austin, TX
Start Date: April 7, 1975
End Date: April 11, 1975
Sponsors: Acoustical Society of America
Accession Number
75A42711
Distribution Limits
Public
Copyright
Other

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