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Book Subjective Response to Simulated Sonic Booms with Ground Reflections

Download or read book Subjective Response to Simulated Sonic Booms with Ground Reflections written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-11 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Sonic Boom Simulator at NASA LaRC was used for the following: (1) quantify subjective loudness of simulated composite sonic booms, each of which was comprised of a simulated direct (non-reflected) boom combined with a simulated reflection of the direct boom; and (2) evaluate several metrics as estimators of loudness for these composite booms. The direct booms consisted of selected N-wave and minimized signatures having front-shock rise times of 3, 6, and 9 milliseconds and durations of 300 milliseconds. Delay times of the reflected booms ranged from 0 to 12 milliseconds. Subjective loudness results indicated that composite booms formed using reflections with non-zero delay times were generally rated as being less loud than composite booms containing non-delayed reflections. The largest reductions in loudness occurred when delay times were equal to the front shock rise times of the direct booms and were, in some cases, equivalent to reductions in Perceived Level of 6 to 7 dB. Results also showed Perceived Level to be an effective metric for assessing subjective loudness effects for the composite signatures. This was confirmed by statistical analysis, which showed that, for equal Perceived Level, no significant differences existed between the subjective loudness responses to composite booms containing reflections with zero delay and those containing reflections with non-zero delays. Sullivan, B. M. and Leatherwood, J. D. Langley Research Center RTOP 537-03-21-03...

Book Subjective Response to Sonic Booms Having Different Shapes Rise Times and Durations

Download or read book Subjective Response to Sonic Booms Having Different Shapes Rise Times and Durations written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-11 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two laboratory experiments were conducted to quantify the subjective response of people to simulated outdoor sonic booms having different pressure signatures. The specific objectives of the experiments were to compare subjective response to sonic booms when described in terms of 'loudness' and 'annoyance'; to determine the ability of various noise metrics to predict subjective response to sonic booms; to determine the effects on subjective response of rise time, duration, and level; and to compare the subjective response to 'N-wave' sonic boom signatures with the subjective response to 'minimized' sonic boom signatures. The experiments were conducted in a computer-controlled, man-rated sonic boom simulator capable of reproducing user-specified pressure signatures for a wide range of sonic boom parameters. One hundred and fifty sonic booms representing different combinations of two wave shapes, four rise times, seven durations, and three peak overpressures were presented to 36 test subjects in each experiment. The test subjects in the first experiment made judgments of 'loudness' while the test subjects in the second experiment judged 'annoyance.' Subjective response to sonic booms was the same whether expressed in terms of loudness or in terms of annoyance. Analyses of several different noise metrics indicated that A-weighted sound exposure level and Perceived Level were the best predictors of subjective response. Further analyses indicated that, of these two noise metrics, only Perceived Level completely accounted for the effects of wave shape, rise time, and peak overpressure. Neither metric fully accounted for the effect of duration. However, the magnitude of the duration effect was small over the very wide range of durations considered. Mccurdy, David A. Langley Research Center RTOP 537-03-21-03...

Book Monthly Catalogue United States Public Documents

Download or read book Monthly Catalogue United States Public Documents written by and published by . This book was released on 1995 with total page 1994 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book A Laboratory Study of Subjective Response to Sonic Booms Measured at White Sands Missile Range

Download or read book A Laboratory Study of Subjective Response to Sonic Booms Measured at White Sands Missile Range written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-28 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Sonic Boom Simulator of the Langley Research Center was used to quantify subjective loudness response to boom signatures consisting of: (1) simulator reproductions of booms recently recorded at White Sands Missile Range; (2) idealized N-waves; and (3) idealized booms having intermediate shocks. The booms with intermediate shocks represented signatures derived from CFD predictions. The recorded booms represented those generated by F15 and T38 aircraft flyovers and represented a variety of waveforms reflecting the effects of propagation through a turbulent atmosphere. These waveforms included the following shape categories: N-waves, peaked, rounded, and U-shaped. Results showed that Perceived Level and Zwicker Loudness Level were good estimators of the loudness of turbulence modified sonic booms. No significant differences were observed between loudness responses for the several shape categories when expressed in terms of Perceived Level. Thus, Perceived Level effectively accounted for waveform differences due to turbulence. Idealized booms with intermediate shocks, however, were rated as being approximately 2.7 dB(PL) less loud than the recorded signatures. This difference was not accounted for by PL. Sullivan, Brenda M. and Leatherwood, Jack D. Langley Research Center RTOP 537-03-21-03...

Book Aeronautical Engineering

Download or read book Aeronautical Engineering written by and published by . This book was released on 1993 with total page 722 pages. Available in PDF, EPUB and Kindle. Book excerpt: A selection of annotated references to unclassified reports and journal articles that were introduced into the NASA scientific and technical information system and announced in Scientific and technical aerospace reports (STAR) and International aerospace abstracts (IAA)

Book A New Simulator for Assessing Subjective Effects of Sonic Booms

Download or read book A New Simulator for Assessing Subjective Effects of Sonic Booms written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-28 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: A man rated and computer driven sonic boom simulator which has been constructed and placed in operational use at NASA-Langley is described. The simulator is used to study human subjective reactions to sonic booms and has the capability of producing a wide range of signatures under controlled conditions. Results are presented to illustrate the capability of the simulator to generate user specified N-wave and shaped booms having rise times as low as 0.5 milliseconds and peak overpressures up to 191 Pa (4 psf). The validity of the simulator as a lab research tool for studying human subjective response to sonic booms was demonstrated by successful completion of a preliminary test designed to compare loudness of N-wave sonic booms with results obtained by other investigators. Excellent agreement of the preliminary test data with existing data was observed. This provided confidence in the experimental methodology and established the simulator as a viable tool for performing detailed evaluations of sonic boom loudness and acceptability within the lab. environment. Leatherwood, Jack D. and Shepherd, Kevin P. and Sullivan, Brenda M. Langley Research Center RTOP 537-03-21-03...

Book NASA SP

    NASA SP

    Book Details:
  • Author :
  • Publisher :
  • Release : 1993
  • ISBN :
  • Pages : 360 pages

Download or read book NASA SP written by and published by . This book was released on 1993 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Scientific and Technical Aerospace Reports

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book High Speed Research Sonic Boom Volume 1

Download or read book High Speed Research Sonic Boom Volume 1 written by and published by . This book was released on 1994 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Innovation in Nonlinear Accoustics ISNA 17

Download or read book Innovation in Nonlinear Accoustics ISNA 17 written by Anthony A. Atchley and published by American Institute of Physics. This book was released on 2006-06-09 with total page 706 pages. Available in PDF, EPUB and Kindle. Book excerpt: State College, Pennsylvania, 18-22 July 2005