Download or read book Subjective Loudness of Sonic boom N wave and Minimized low boom Signatures written by A. Niedzwiecki and published by . This book was released on 1977 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: A loudspeaker-driven simulation booth with extended rise-time capability (down to 0.22 ms) has been used for subjective loudness tests of sonic booms. Test series I compared N-waves over a range of 0.22 to 10 ms rise time, 100 to 250 ms duration and 0.5 to 2.0 psf (24 to 96 N/sq m) peak overpressure. In one sequence, tradeoff between rise time and overpressure was measured for equal loudness; in another, the tradeoff between duration and overpressure. For equal loudness 10 ms rise time required 8 dB higher overpressure than for 1 ms rise time. Duration had little effect in the range 100 to 200 ms but at 250 ms noticeably enhanced the loudness. These results confirm those measured by Shepherd and Sutherland, made at 1 ms rise time and above (except for the anomalous enhancement at 250 ms duration), and extend the measurements down to 0.22 ms. There is also good agreement with theoretical predictions (Johnson-Robinson, Zepler-Harel methods) except for the 10 ms rise time and 250 ms duration cases.

Download or read book Subjective Loudness of Sonic boon N wave and Minimized low boom Signatures written by A. Niedzwiecki and published by . This book was released on 1977 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Loudness Calculation Procedure Applied to Shaped Sonic Booms written by Kevin P. Shepherd and published by . This book was released on 1991 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Subjective Response to Sonic Booms Having Different Shapes Rise Times and Durations written by David A. McCurdy and published by . This book was released on 1994 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Subjective Response to Simulated Sonic Booms with Ground Reflections written by B. M. Sullivan and published by . This book was released on 1993 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A New Simulator for Assessing Subjective Effects of Sonic Booms written by and published by . This book was released on 1991 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Laboratory Study of Effects of Sonic Boom Shaping on Subjective Loudness and Acceptability written by Jack D. Leatherwood and published by . This book was released on 1992 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Loudness Calculation Procedure Applied to Shaped Sonic Booms written by Kevin P. Shepherd and published by . This book was released on 1991 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book On the Loudness of Sonic Booms and Other Impulsive Sounds written by A. Niedzwiecki and published by . This book was released on 1978 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: A loudspeaker-driven simulation booth with extended rise time capability (down to 0.22 ms) has been used for subjective loudness tests of sonic-boom and other types of impulsive sounds. The first series compared N-waves over a range of 0.22 to 10 ms rise time, 100 to 250 ms duration and from 0.5 to 4 psf (the latter for the longer rise times) (24 to 192 N/sq m) peak overpressure. The response tradeoff between rise time and overpressure, and duration and overpressure was measured. The second series tested certain 'flat top' sonic boom signatures, which according to current theory could be generated by special very long SST aircraft designed for minimized sonic-boom; these were compared for loudness with a reference N-wave (pN = 0.5 psf, 1 ms rise time, 150 ms duration). The third series compared filtered N-wave signatures, using a highpass digital filter with an unfiltered N-wave signature (1 psf, 1 ms rise time, 150 ms duration). In the last test series the tradeoff between overpressure and duration was found for idealized quarry blast signatures composed of sequences of 25 ms long pulses with 0.22 ms rise time. The range of durations extended from 25 to 400 ms. The results in each series were compared with theoretical predictions by the method of Johnson and Robinson. All but the long-duration quarry blast judgements were found to be in very good agreement in terms of relative loudness levels.

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...

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...

Download or read book Effect of Sonic Boom Asymmetry on Subjective Loudness written by Jack D. Leatherwood and published by . This book was released on 1992 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The NASA Langley Research Center's sonic boom apparatus was used in an experimental study to quantify subjective loudness response to a wide range of asymmetrical N-wave sonic boom signatures. Results were used to assess the relative performance of several metrics as loudness estimators for asymmetrical signatures and to quantify in detail the effects on subjective loudness of varying both the degree and direction of signature loudness asymmetry. Findings of the study indicated that Perceived Level (Steven's Mark 7) and A-weighted sound exposure level were the best metrics for quantifying asymmetrical boom loudness. Asymmetrical signatures were generally rated as being less loud than symmetrical signatures of equivalent Perceived Level. The magnitude of the loudness reductions increased as the degree of boom asymmetry increased, and depended upon the direction of asymmetry. These loudness reductions were not accounted for by any of the metrics. Corrections were determined for use in adjusting calculated Perceived Level values to account for these reductions. It was also demonstrated that the subjects generally incorporated the loudness components of the complete signatures when making their subjective judgments.

Download or read book Laboratory Study of Effects of Sonic Boom Shaping on Subjective Loudness and Acceptability written by National Aeronautics and Space Adm Nasa and published by . This book was released on 2018-10-20 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: A laboratory study was conducted to determine the effects of sonic boom signature shaping on subjective loudness and acceptability. The study utilized the sonic boom simulator at the Langley Research Center. A wide range of symmetrical, front-shock-minimized signature shapes were investigated together with a limited number of asymmetrical signatures. Subjective loudness judgments were obtained from 60 test subjects by using an 11-point numerical category scale. Acceptability judgments were obtained using the method of constant stimuli. Results were used to assess the relative predictive ability of several noise metrics, determine the loudness benefits of detailed boom shaping, and derive laboratory sonic boom acceptability criteria. These results indicated that the A-weighted sound exposure level, the Stevens Mark 7 Perceived Level, and the Zwicker Loudness Level metrics all performed well. Significant reductions in loudness were obtained by increasing front-shock rise time and/or decreasing front-shock overpressure of the front-shock minimized signatures. In addition, the asymmetrical signatures were rated to be slightly quieter than the symmetrical front-shock-minimized signatures of equal A-weighted sound exposure level. However, this result was based on a limited number of asymmetric signatures. The comparison of laboratory acceptability results with acceptability data obtained in more realistic situations also indicated good agreement. Leatherwood, Jack D. and Sullivan, Brenda M. Langley Research Center RTOP 537-03-21-03...

Download or read book Evaluation of Outdoor to indoor Response to Minimized Sonic Booms written by David Brown and published by . This book was released on 1992 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effect of Sonic Boom Asymmetry on Subjective Loudness written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-03 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: The NASA Langley Research Center's sonic boom apparatus was used in an experimental study to quantify subjective loudness response to a wide range of asymmetrical N-wave sonic boom signatures. Results were used to assess the relative performance of several metrics as loudness estimators for asymmetrical signatures and to quantify in detail the effects on subjective loudness of varying both the degree and direction of signature loudness asymmetry. Findings of the study indicated that Perceived Level (Steven's Mark 7) and A-weighted sound exposure level were the best metrics for quantifying asymmetrical boom loudness. Asymmetrical signatures were generally rated as being less loud than symmetrical signatures of equivalent Perceived Level. The magnitude of the loudness reductions increased as the degree of boom asymmetry increased, and depended upon the direction of asymmetry. These loudness reductions were not accounted for by any of the metrics. Corrections were determined for use in adjusting calculated Perceived Level values to account for these reductions. It was also demonstrated that the subjects generally incorporated the loudness components of the complete signatures when making their subjective judgments. Leatherwood, Jack D. and Sullivan, Brenda M. Langley Research Center RTOP 537-03-21-03...

Download or read book A Laboratory Study of Subjective Response to Sonic Booms Measured at White Sands Missile Range written by and published by . This book was released on 1993 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Sonic boom Research written by Harvey H. Hubbard and published by . This book was released on 1986 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: