Low-frequency (LF) room modes are one of the greatest issues for accurate sound recording and reproduction. Effective LF absorbers can mitigate modes in professional and consumer audio rooms. However, fiber- and foam-based absorbers act on sound velocity; membrane absorbers act on sound pressure (greatest at hard surfaces and corners). Velocity at hard surfaces is zero; thus, fiber and foam absorbers work far less effectively than membrane absorbers under 200Hz. Additionally, most independent testing laboratories are only large enough to accurately measure absorption results above 160Hz (per Schroeder frequency) but not below. Only one lab is large enough to be accurate down to 40Hz. A new LF membrane-based absorber product was designed to compliment the frequency range of an existing product. Both were separately tested for LF absorption down to 40Hz at the above-referenced lab. Ten LF absorber tests revealed that the type of absorber, and its location and orientation in a room, are critical to LF absorber effectiveness. Some unexpected results, however, showed clearly that without standardized laboratory absorption testing in a lab capable of accurately testing down to 40Hz, it is not possible to state conclusively that low-frequency absorber products perform as claimed.Low-frequency (LF) room modes are one of the greatest issues for accurate sound recording and reproduction. Effective LF absorbers can mitigate modes in professional and consumer audio rooms. However, fiber- and foam-based absorbers act on sound velocity; membrane absorbers act on sound pressure (greatest at hard surfaces and corners). Velocity at hard surfaces is zero; thus, fiber and foam absorbers work far less effectively than membrane absorbers under 200Hz. Additionally, most independent testing laboratories are only large enough to accurately measure absorption results above 160Hz (per Schroeder frequency) but not below. Only one lab is large enough to be accurate down to 40Hz. A new LF membrane-based absorber product was designed to compliment the frequency range of an existing product. Both were separately tested for LF absorption down to 40Hz at the above-referenced lab. Ten LF absorber tests revealed that the type of absorber, and its location and orientation in a room, are critical to LF absorb...
{"title":"New research on low-frequency membrane absorbers","authors":"John Calder","doi":"10.1121/2.0000816","DOIUrl":"https://doi.org/10.1121/2.0000816","url":null,"abstract":"Low-frequency (LF) room modes are one of the greatest issues for accurate sound recording and reproduction. Effective LF absorbers can mitigate modes in professional and consumer audio rooms. However, fiber- and foam-based absorbers act on sound velocity; membrane absorbers act on sound pressure (greatest at hard surfaces and corners). Velocity at hard surfaces is zero; thus, fiber and foam absorbers work far less effectively than membrane absorbers under 200Hz. Additionally, most independent testing laboratories are only large enough to accurately measure absorption results above 160Hz (per Schroeder frequency) but not below. Only one lab is large enough to be accurate down to 40Hz. A new LF membrane-based absorber product was designed to compliment the frequency range of an existing product. Both were separately tested for LF absorption down to 40Hz at the above-referenced lab. Ten LF absorber tests revealed that the type of absorber, and its location and orientation in a room, are critical to LF absorber effectiveness. Some unexpected results, however, showed clearly that without standardized laboratory absorption testing in a lab capable of accurately testing down to 40Hz, it is not possible to state conclusively that low-frequency absorber products perform as claimed.Low-frequency (LF) room modes are one of the greatest issues for accurate sound recording and reproduction. Effective LF absorbers can mitigate modes in professional and consumer audio rooms. However, fiber- and foam-based absorbers act on sound velocity; membrane absorbers act on sound pressure (greatest at hard surfaces and corners). Velocity at hard surfaces is zero; thus, fiber and foam absorbers work far less effectively than membrane absorbers under 200Hz. Additionally, most independent testing laboratories are only large enough to accurately measure absorption results above 160Hz (per Schroeder frequency) but not below. Only one lab is large enough to be accurate down to 40Hz. A new LF membrane-based absorber product was designed to compliment the frequency range of an existing product. Both were separately tested for LF absorption down to 40Hz at the above-referenced lab. Ten LF absorber tests revealed that the type of absorber, and its location and orientation in a room, are critical to LF absorb...","PeriodicalId":20469,"journal":{"name":"Proc. Meet. Acoust.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81399566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Paul B. Russavage, T. Neilsen, K. Gee, S. H. Swift
Crackle is a perceptual aspect of noise caused by impulsive acoustic shocks and observed in noise from supersonic jets, including those from military aircraft and rockets. Overall and long-term spectral noise metrics do not account for the unique perception of crackle. Listening tests were designed to better understand perception of crackle and examine its relationship to physical noise metrics, such as skewness of the first time derivative of the pressure waveform, hereafter derivative skewness. It is hypothesized that as derivative skewness increases, the perception of crackle tends to increase. Two listening tests were conducted with 31 subjects to examine their perception of crackle. In the first test, subjects compared and ordered crackle-containing sounds. In the second test, category scaling was employed with subjects rating the crackle content with category labels: 1) smooth noise with no crackle, 2) rough noise with no crackle, 3) sporadic or intermittent crackle, 4) continuous crackle, and 5) intense crackle. Both the order and rating tests confirm there is a high correlation between perception of crackle and derivative skewness. These insights will help inform community noise models, allowing them to incorporate annoyance due to jet crackle.Crackle is a perceptual aspect of noise caused by impulsive acoustic shocks and observed in noise from supersonic jets, including those from military aircraft and rockets. Overall and long-term spectral noise metrics do not account for the unique perception of crackle. Listening tests were designed to better understand perception of crackle and examine its relationship to physical noise metrics, such as skewness of the first time derivative of the pressure waveform, hereafter derivative skewness. It is hypothesized that as derivative skewness increases, the perception of crackle tends to increase. Two listening tests were conducted with 31 subjects to examine their perception of crackle. In the first test, subjects compared and ordered crackle-containing sounds. In the second test, category scaling was employed with subjects rating the crackle content with category labels: 1) smooth noise with no crackle, 2) rough noise with no crackle, 3) sporadic or intermittent crackle, 4) continuous crackle, and 5) in...
{"title":"Rating the perception of jet noise crackle","authors":"Paul B. Russavage, T. Neilsen, K. Gee, S. H. Swift","doi":"10.1121/2.0000821","DOIUrl":"https://doi.org/10.1121/2.0000821","url":null,"abstract":"Crackle is a perceptual aspect of noise caused by impulsive acoustic shocks and observed in noise from supersonic jets, including those from military aircraft and rockets. Overall and long-term spectral noise metrics do not account for the unique perception of crackle. Listening tests were designed to better understand perception of crackle and examine its relationship to physical noise metrics, such as skewness of the first time derivative of the pressure waveform, hereafter derivative skewness. It is hypothesized that as derivative skewness increases, the perception of crackle tends to increase. Two listening tests were conducted with 31 subjects to examine their perception of crackle. In the first test, subjects compared and ordered crackle-containing sounds. In the second test, category scaling was employed with subjects rating the crackle content with category labels: 1) smooth noise with no crackle, 2) rough noise with no crackle, 3) sporadic or intermittent crackle, 4) continuous crackle, and 5) intense crackle. Both the order and rating tests confirm there is a high correlation between perception of crackle and derivative skewness. These insights will help inform community noise models, allowing them to incorporate annoyance due to jet crackle.Crackle is a perceptual aspect of noise caused by impulsive acoustic shocks and observed in noise from supersonic jets, including those from military aircraft and rockets. Overall and long-term spectral noise metrics do not account for the unique perception of crackle. Listening tests were designed to better understand perception of crackle and examine its relationship to physical noise metrics, such as skewness of the first time derivative of the pressure waveform, hereafter derivative skewness. It is hypothesized that as derivative skewness increases, the perception of crackle tends to increase. Two listening tests were conducted with 31 subjects to examine their perception of crackle. In the first test, subjects compared and ordered crackle-containing sounds. In the second test, category scaling was employed with subjects rating the crackle content with category labels: 1) smooth noise with no crackle, 2) rough noise with no crackle, 3) sporadic or intermittent crackle, 4) continuous crackle, and 5) in...","PeriodicalId":20469,"journal":{"name":"Proc. Meet. Acoust.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75223213","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Multisource statistically optimized near-field acoustical holography (M-SONAH) improves the field reconstruction process by directly incorporating into the pressure propagator types of wavefunctions that correspond most closely to the source geometries of interest [A. T. Wall et al., J. Acoust. Soc. Am. 137, 963–975 (2015)]. The M-SONAH method has previously been used to localize acoustic sources in a full-scale jet engine plume above a rigid reflecting plane by adding a second set of cylindrical wavefunctions corresponding to the image source [A. T. Wall et al. J. Acoust. Soc. Am. 139, 1938–1950 (2016)]. Here, M-SONAH theory is extended to obtain the vector particle velocity and, by extension, the acoustic intensity. Discussed are two examples that relate to the full-scale jet noise-with-image-plane reconstruction problem: (1) a Gaussian line source with image and (2) a jet-like wavepacket and image, with hologram geometry identical to that of the full-scale experiment. The results from both examples rev...
{"title":"Obtaining acoustic intensity from multisource statistically optimized near-field acoustical holography","authors":"Trevor A. Stout, Alan T. Wall, K. Gee, T. Neilsen","doi":"10.1121/2.0000835","DOIUrl":"https://doi.org/10.1121/2.0000835","url":null,"abstract":"Multisource statistically optimized near-field acoustical holography (M-SONAH) improves the field reconstruction process by directly incorporating into the pressure propagator types of wavefunctions that correspond most closely to the source geometries of interest [A. T. Wall et al., J. Acoust. Soc. Am. 137, 963–975 (2015)]. The M-SONAH method has previously been used to localize acoustic sources in a full-scale jet engine plume above a rigid reflecting plane by adding a second set of cylindrical wavefunctions corresponding to the image source [A. T. Wall et al. J. Acoust. Soc. Am. 139, 1938–1950 (2016)]. Here, M-SONAH theory is extended to obtain the vector particle velocity and, by extension, the acoustic intensity. Discussed are two examples that relate to the full-scale jet noise-with-image-plane reconstruction problem: (1) a Gaussian line source with image and (2) a jet-like wavepacket and image, with hologram geometry identical to that of the full-scale experiment. The results from both examples rev...","PeriodicalId":20469,"journal":{"name":"Proc. Meet. Acoust.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86967658","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The bundengan is an endangered musical instrument from Indonesia. This musical instrument was first developed and played by duck herders. To build the half-dome-shaped resonator, bundengan makers create a woven grid of bamboo splits and arrange the weaving pattern such that the grid spontaneously forms the half-dome shape. The dome is then coated with layers of bamboo sheaths, strapped with sugar palm fibres to hold them in place. Inside the resonator, there is a set of long, thin bamboo plates and some strings. The strings are equipped with small bamboo clips, which vibrate together with the strings. The clipped strings generate metal-like sounds, while the bamboo plates generate drum-like sounds, such that the bundengan as a whole imitates the sound of a set of gamelan, an Indonesian instrumental ensemble. Interactions with the bundengan makers and players allow us to identify an important problem: players find it difficult not only to tune this instrument, but also to keep it tuned for a long time. We ...
{"title":"Computational analysis of the bundengan, an endangered musical instrument from Indonesia","authors":"I. Kusumaningtyas, G. Parikesit","doi":"10.1121/2.0000800","DOIUrl":"https://doi.org/10.1121/2.0000800","url":null,"abstract":"The bundengan is an endangered musical instrument from Indonesia. This musical instrument was first developed and played by duck herders. To build the half-dome-shaped resonator, bundengan makers create a woven grid of bamboo splits and arrange the weaving pattern such that the grid spontaneously forms the half-dome shape. The dome is then coated with layers of bamboo sheaths, strapped with sugar palm fibres to hold them in place. Inside the resonator, there is a set of long, thin bamboo plates and some strings. The strings are equipped with small bamboo clips, which vibrate together with the strings. The clipped strings generate metal-like sounds, while the bamboo plates generate drum-like sounds, such that the bundengan as a whole imitates the sound of a set of gamelan, an Indonesian instrumental ensemble. Interactions with the bundengan makers and players allow us to identify an important problem: players find it difficult not only to tune this instrument, but also to keep it tuned for a long time. We ...","PeriodicalId":20469,"journal":{"name":"Proc. Meet. Acoust.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87761715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We propose a novel low latency smartphone-based application that demonstrates the real-time operation to cancel the negative effects of acoustic feedback arising from the coupling between the speaker and the microphone of the smartphone or similar device utilizing the robust Noise Injection (NI) method. We make use of multiple noise injections of short durations to estimate the filter coefficients of an appropriate order between the speaker and the microphone, in order to perform the feedback cancellation effectively in real-time. Our motive behind the development of this application is to perform an effective acoustic feedback cancellation irrespective of the position of speaker and the microphone on the platform under consideration. With the proposed application, we can estimate the transfer function between speaker and microphone in the changing room acoustics making the feedback cancellation very effective. Objective and subjective tests were conducted and results of the proposed real-time application indicate significant acoustic feedback suppression in the presence of varying environmental conditions.We propose a novel low latency smartphone-based application that demonstrates the real-time operation to cancel the negative effects of acoustic feedback arising from the coupling between the speaker and the microphone of the smartphone or similar device utilizing the robust Noise Injection (NI) method. We make use of multiple noise injections of short durations to estimate the filter coefficients of an appropriate order between the speaker and the microphone, in order to perform the feedback cancellation effectively in real-time. Our motive behind the development of this application is to perform an effective acoustic feedback cancellation irrespective of the position of speaker and the microphone on the platform under consideration. With the proposed application, we can estimate the transfer function between speaker and microphone in the changing room acoustics making the feedback cancellation very effective. Objective and subjective tests were conducted and results of the proposed real-time application...
{"title":"Robust real-time implementation of adaptive feedback cancellation using noise injection algorithm on smartphone","authors":"Parth Mishra, Serkan Tokgoz, I. Panahi","doi":"10.1121/2.0000836","DOIUrl":"https://doi.org/10.1121/2.0000836","url":null,"abstract":"We propose a novel low latency smartphone-based application that demonstrates the real-time operation to cancel the negative effects of acoustic feedback arising from the coupling between the speaker and the microphone of the smartphone or similar device utilizing the robust Noise Injection (NI) method. We make use of multiple noise injections of short durations to estimate the filter coefficients of an appropriate order between the speaker and the microphone, in order to perform the feedback cancellation effectively in real-time. Our motive behind the development of this application is to perform an effective acoustic feedback cancellation irrespective of the position of speaker and the microphone on the platform under consideration. With the proposed application, we can estimate the transfer function between speaker and microphone in the changing room acoustics making the feedback cancellation very effective. Objective and subjective tests were conducted and results of the proposed real-time application indicate significant acoustic feedback suppression in the presence of varying environmental conditions.We propose a novel low latency smartphone-based application that demonstrates the real-time operation to cancel the negative effects of acoustic feedback arising from the coupling between the speaker and the microphone of the smartphone or similar device utilizing the robust Noise Injection (NI) method. We make use of multiple noise injections of short durations to estimate the filter coefficients of an appropriate order between the speaker and the microphone, in order to perform the feedback cancellation effectively in real-time. Our motive behind the development of this application is to perform an effective acoustic feedback cancellation irrespective of the position of speaker and the microphone on the platform under consideration. With the proposed application, we can estimate the transfer function between speaker and microphone in the changing room acoustics making the feedback cancellation very effective. Objective and subjective tests were conducted and results of the proposed real-time application...","PeriodicalId":20469,"journal":{"name":"Proc. Meet. Acoust.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84897799","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Thomas E. Blanford, Micah R. Shepherd, Trevor W. Jerome
Fractional-sized cellos (3/4, 1/2, etc.) are designed for the same musical playing range as a full-sized (4/4) cello but with scaled proportions for players for whom a full-sized cello is too large. The strings are adjusted in order to compensate for the shorter string length of the smaller instruments and obtain the correct tuning. The cello body vibration, which is strongly coupled to the internal air cavity, would not be expected to scale in the same manner as the strings. This causes the bridge impedance seen by the strings on the fractional-sized cellos to differ from the bridge impedance seen by the strings on a full-sized cello. In this paper, the physical dimensions of a 1/2 and 3/4 cello are compared with a full cello. Drive point measurements are also compared to illustrate how the strings couple differently with the body of each size cello. The fractional-sized cellos are found to exhibit a slightly different sound due to the bridge impedance mismatch.Fractional-sized cellos (3/4, 1/2, etc.) are designed for the same musical playing range as a full-sized (4/4) cello but with scaled proportions for players for whom a full-sized cello is too large. The strings are adjusted in order to compensate for the shorter string length of the smaller instruments and obtain the correct tuning. The cello body vibration, which is strongly coupled to the internal air cavity, would not be expected to scale in the same manner as the strings. This causes the bridge impedance seen by the strings on the fractional-sized cellos to differ from the bridge impedance seen by the strings on a full-sized cello. In this paper, the physical dimensions of a 1/2 and 3/4 cello are compared with a full cello. Drive point measurements are also compared to illustrate how the strings couple differently with the body of each size cello. The fractional-sized cellos are found to exhibit a slightly different sound due to the bridge impedance mismatch.
{"title":"A comparison of fractional-sized to full-sized cellos","authors":"Thomas E. Blanford, Micah R. Shepherd, Trevor W. Jerome","doi":"10.1121/2.0000841","DOIUrl":"https://doi.org/10.1121/2.0000841","url":null,"abstract":"Fractional-sized cellos (3/4, 1/2, etc.) are designed for the same musical playing range as a full-sized (4/4) cello but with scaled proportions for players for whom a full-sized cello is too large. The strings are adjusted in order to compensate for the shorter string length of the smaller instruments and obtain the correct tuning. The cello body vibration, which is strongly coupled to the internal air cavity, would not be expected to scale in the same manner as the strings. This causes the bridge impedance seen by the strings on the fractional-sized cellos to differ from the bridge impedance seen by the strings on a full-sized cello. In this paper, the physical dimensions of a 1/2 and 3/4 cello are compared with a full cello. Drive point measurements are also compared to illustrate how the strings couple differently with the body of each size cello. The fractional-sized cellos are found to exhibit a slightly different sound due to the bridge impedance mismatch.Fractional-sized cellos (3/4, 1/2, etc.) are designed for the same musical playing range as a full-sized (4/4) cello but with scaled proportions for players for whom a full-sized cello is too large. The strings are adjusted in order to compensate for the shorter string length of the smaller instruments and obtain the correct tuning. The cello body vibration, which is strongly coupled to the internal air cavity, would not be expected to scale in the same manner as the strings. This causes the bridge impedance seen by the strings on the fractional-sized cellos to differ from the bridge impedance seen by the strings on a full-sized cello. In this paper, the physical dimensions of a 1/2 and 3/4 cello are compared with a full cello. Drive point measurements are also compared to illustrate how the strings couple differently with the body of each size cello. The fractional-sized cellos are found to exhibit a slightly different sound due to the bridge impedance mismatch.","PeriodicalId":20469,"journal":{"name":"Proc. Meet. Acoust.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87458584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Panfilova, R. J. Sloun, R. Wildeboer, H. Wijkstra, M. Mischi
A practical method is proposed to assess the ultrasound coefficient of nonlinearity of a medium by measuring the fundamental and 2nd harmonic in the near field of a plane piston source for varying source pressure. The method uses the Fubini solution to extract the slope of the linear dependency of the ratio harmonic/fundamental on the fundamental pressure measured at the same location. It eliminates the need for a motion stage, required by methods observing harmonic growth with source distance. It also excludes the need to measure the pressure at the source, since, in the current experiment, conducted in distilled water, it neglects depletion of the fundamental due to attenuation and energy transfer to higher harmonics. The variability of the estimated beta was evaluated with 9 measurements for which the setup was mounted anew. This was performed for 4 different distances from the source. The estimated beta slightly decreased with increasing distance from the source, possibly due to focusing effects. The average beta estimated over all measurements was 3.48+−0.43, showing good agreement with previously reported values. The reproducibility and accuracy of the proposed method is relevant for its adoption aimed at beta measurements in tissue samples for clinical diagnostic research.
{"title":"A fixed-distance plane wave method for estimating the ultrasound coefficient of nonlinearity","authors":"A. Panfilova, R. J. Sloun, R. Wildeboer, H. Wijkstra, M. Mischi","doi":"10.1121/2.0000855","DOIUrl":"https://doi.org/10.1121/2.0000855","url":null,"abstract":"A practical method is proposed to assess the ultrasound coefficient of nonlinearity of a medium by measuring the fundamental and 2nd harmonic in the near field of a plane piston source for varying source pressure. The method uses the Fubini solution to extract the slope of the linear dependency of the ratio harmonic/fundamental on the fundamental pressure measured at the same location. It eliminates the need for a motion stage, required by methods observing harmonic growth with source distance. It also excludes the need to measure the pressure at the source, since, in the current experiment, conducted in distilled water, it neglects depletion of the fundamental due to attenuation and energy transfer to higher harmonics. The variability of the estimated beta was evaluated with 9 measurements for which the setup was mounted anew. This was performed for 4 different distances from the source. The estimated beta slightly decreased with increasing distance from the source, possibly due to focusing effects. The average beta estimated over all measurements was 3.48+−0.43, showing good agreement with previously reported values. The reproducibility and accuracy of the proposed method is relevant for its adoption aimed at beta measurements in tissue samples for clinical diagnostic research.","PeriodicalId":20469,"journal":{"name":"Proc. Meet. Acoust.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76136119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A frequency-domain representation of the Burgers equation reveals that the cross-spectrum between the pressure and pressure-squared waveforms can be used to calculate nonlinear frequency-domain effects of finite-amplitude sound propagation. The normalized version of the quadspectrum, Q/S, was introduced by Morfey and Howell and has since been used to point to the nonlinear transfer of energy between frequencies, in particular gaining use in the domain of high-amplitude jet noise propagation. However, one question that remained was that of the interpretation: The physical meaning of the amplitude of Q/S was unclear. Recent analytical work has recast Q/S and the normalized version of the cospectrum, C/S, as a way to estimate sound pressure level and phase changes due to nonlinearity with a single-point measurement. This paper uses various measurements within a plane-wave tube to verify the physical significance of the amplitude and phase changes predicted by Q/S and C/S. Experiments involving sinusoids and band-passed Gaussian noise at various amplitudes show the validity of the single-point measurement to measure the strength of nonlinear effects in both amplitude and phase.A frequency-domain representation of the Burgers equation reveals that the cross-spectrum between the pressure and pressure-squared waveforms can be used to calculate nonlinear frequency-domain effects of finite-amplitude sound propagation. The normalized version of the quadspectrum, Q/S, was introduced by Morfey and Howell and has since been used to point to the nonlinear transfer of energy between frequencies, in particular gaining use in the domain of high-amplitude jet noise propagation. However, one question that remained was that of the interpretation: The physical meaning of the amplitude of Q/S was unclear. Recent analytical work has recast Q/S and the normalized version of the cospectrum, C/S, as a way to estimate sound pressure level and phase changes due to nonlinearity with a single-point measurement. This paper uses various measurements within a plane-wave tube to verify the physical significance of the amplitude and phase changes predicted by Q/S and C/S. Experiments involving sinusoids and ...
{"title":"Single-point characterization of spectral amplitude and phase changes due to nonlinear propagation","authors":"Brent O. Reichman, K. Gee, W. Ohm","doi":"10.1121/2.0000870","DOIUrl":"https://doi.org/10.1121/2.0000870","url":null,"abstract":"A frequency-domain representation of the Burgers equation reveals that the cross-spectrum between the pressure and pressure-squared waveforms can be used to calculate nonlinear frequency-domain effects of finite-amplitude sound propagation. The normalized version of the quadspectrum, Q/S, was introduced by Morfey and Howell and has since been used to point to the nonlinear transfer of energy between frequencies, in particular gaining use in the domain of high-amplitude jet noise propagation. However, one question that remained was that of the interpretation: The physical meaning of the amplitude of Q/S was unclear. Recent analytical work has recast Q/S and the normalized version of the cospectrum, C/S, as a way to estimate sound pressure level and phase changes due to nonlinearity with a single-point measurement. This paper uses various measurements within a plane-wave tube to verify the physical significance of the amplitude and phase changes predicted by Q/S and C/S. Experiments involving sinusoids and band-passed Gaussian noise at various amplitudes show the validity of the single-point measurement to measure the strength of nonlinear effects in both amplitude and phase.A frequency-domain representation of the Burgers equation reveals that the cross-spectrum between the pressure and pressure-squared waveforms can be used to calculate nonlinear frequency-domain effects of finite-amplitude sound propagation. The normalized version of the quadspectrum, Q/S, was introduced by Morfey and Howell and has since been used to point to the nonlinear transfer of energy between frequencies, in particular gaining use in the domain of high-amplitude jet noise propagation. However, one question that remained was that of the interpretation: The physical meaning of the amplitude of Q/S was unclear. Recent analytical work has recast Q/S and the normalized version of the cospectrum, C/S, as a way to estimate sound pressure level and phase changes due to nonlinearity with a single-point measurement. This paper uses various measurements within a plane-wave tube to verify the physical significance of the amplitude and phase changes predicted by Q/S and C/S. Experiments involving sinusoids and ...","PeriodicalId":20469,"journal":{"name":"Proc. Meet. Acoust.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78408729","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nonlinear vibration behaviors present an opportunity to probe natural composite materials with an undefined level of detail. Existing characterization techniques for composite materials are often limited in resolution due to the heterogeneous nature of composite materials. The work carried out in this paper aims to optically observe the micro-structure of cement paste before and after a series high strain vibration events. Images are captured at multiple levels of driven vibration and compared against an initial reference image. Small changes in optical microscopy are recorded, however no optically sized cohesive regions of change are identified after all levels of excitation. The work builds a consensus that more advanced imaging techniques are required to continue to investigate dynamic nonlinear manifestation of the natural composite material micro-structures.
{"title":"Efforts on optical scale imaging for physically observing slow dynamics","authors":"J. Bittner, J. Popovics","doi":"10.1121/2.0000860","DOIUrl":"https://doi.org/10.1121/2.0000860","url":null,"abstract":"Nonlinear vibration behaviors present an opportunity to probe natural composite materials with an undefined level of detail. Existing characterization techniques for composite materials are often limited in resolution due to the heterogeneous nature of composite materials. The work carried out in this paper aims to optically observe the micro-structure of cement paste before and after a series high strain vibration events. Images are captured at multiple levels of driven vibration and compared against an initial reference image. Small changes in optical microscopy are recorded, however no optically sized cohesive regions of change are identified after all levels of excitation. The work builds a consensus that more advanced imaging techniques are required to continue to investigate dynamic nonlinear manifestation of the natural composite material micro-structures.","PeriodicalId":20469,"journal":{"name":"Proc. Meet. Acoust.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83247678","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. Gee, Caroline P. Lubert, Alan T. Wall, S. Tsutsumi
This paper summarizes a two-part special session, “Supersonic Jet and Rocket Noise,” which was held during the 174th Meeting of the Acoustical Society of America in New Orleans, Louisiana. The sessions were cosponsored by the Noise and Physical Acoustics Technical Committees and consisted of talks by government, academic, and industry researchers from institutions in the United States, Japan, France, and India. The sessions described analytical, computational, and experimental approaches to both fundamental and applied problems on model and full-scale jets and rocket exhaust plumes.
{"title":"Summary of \"Supersonic Jet and Rocket Noise\"","authors":"K. Gee, Caroline P. Lubert, Alan T. Wall, S. Tsutsumi","doi":"10.1121/2.0000655","DOIUrl":"https://doi.org/10.1121/2.0000655","url":null,"abstract":"This paper summarizes a two-part special session, “Supersonic Jet and Rocket Noise,” which was held during the 174th Meeting of the Acoustical Society of America in New Orleans, Louisiana. The sessions were cosponsored by the Noise and Physical Acoustics Technical Committees and consisted of talks by government, academic, and industry researchers from institutions in the United States, Japan, France, and India. The sessions described analytical, computational, and experimental approaches to both fundamental and applied problems on model and full-scale jets and rocket exhaust plumes.","PeriodicalId":20469,"journal":{"name":"Proc. Meet. Acoust.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82698126","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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