Pub Date : 2022-11-15DOI: 10.3390/acoustics4040060
Yehav Alkaher, I. Cohen
In this paper, we address the problem of howling detection in speech reinforcement system applications for utilization in howling control mechanisms. A general speech reinforcement system acquires speech from a speaker’s microphone, and delivers a reinforced speech to other listeners in the same room, or another room, through loudspeakers. The amount of gain that can be applied to the acquired speech in the closed-loop system is constrained by electro-acoustic coupling in the system, manifested in howling noises appearing as a result of acoustic feedback. A howling detection algorithm aims to early detect frequency-howls in the system, before the human ear notices. The proposed algorithm includes two cascaded stages: Soft Howling Detection and Howling False-Alarm Detection. The Soft Howling Detection is based on the temporal magnitude-slope-deviation measure, identifying potential candidate frequency-howls. Inspired by the temporal approach, the Howling False-Alarm Detection stage considers the understanding of speech-signal frequency components’ magnitude behavior under different levels of acoustic feedback. A comprehensive howling detection performance evaluation process is designed, examining the proposed algorithm in terms of detection accuracy and the time it takes for detection, under a devised set of howling scenarios. The performance improvement of the proposed algorithm, with respect to a plain magnitude-slope-deviation-based method, is demonstrated by showing faster detection response times over a set of howling change-rate configurations. The two-staged proposed algorithm also provides a significant recall improvement, while improving the precision decrease via the Howling False-Alarm Detection stage.
{"title":"Temporal Howling Detector for Speech Reinforcement Systems","authors":"Yehav Alkaher, I. Cohen","doi":"10.3390/acoustics4040060","DOIUrl":"https://doi.org/10.3390/acoustics4040060","url":null,"abstract":"In this paper, we address the problem of howling detection in speech reinforcement system applications for utilization in howling control mechanisms. A general speech reinforcement system acquires speech from a speaker’s microphone, and delivers a reinforced speech to other listeners in the same room, or another room, through loudspeakers. The amount of gain that can be applied to the acquired speech in the closed-loop system is constrained by electro-acoustic coupling in the system, manifested in howling noises appearing as a result of acoustic feedback. A howling detection algorithm aims to early detect frequency-howls in the system, before the human ear notices. The proposed algorithm includes two cascaded stages: Soft Howling Detection and Howling False-Alarm Detection. The Soft Howling Detection is based on the temporal magnitude-slope-deviation measure, identifying potential candidate frequency-howls. Inspired by the temporal approach, the Howling False-Alarm Detection stage considers the understanding of speech-signal frequency components’ magnitude behavior under different levels of acoustic feedback. A comprehensive howling detection performance evaluation process is designed, examining the proposed algorithm in terms of detection accuracy and the time it takes for detection, under a devised set of howling scenarios. The performance improvement of the proposed algorithm, with respect to a plain magnitude-slope-deviation-based method, is demonstrated by showing faster detection response times over a set of howling change-rate configurations. The two-staged proposed algorithm also provides a significant recall improvement, while improving the precision decrease via the Howling False-Alarm Detection stage.","PeriodicalId":72045,"journal":{"name":"Acoustics (Basel, Switzerland)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42170610","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}
Pub Date : 2022-11-15DOI: 10.3390/acoustics4040061
M. Lematre, M. Lethiecq
This paper presents the possibility of enhancement of the generation and detection of poorly energetic acoustic-guided waves in multilayered structures using a new design for a V(z) transducer. By defining a modified V(z) transducer composed of segmented piezoelectric elements, the acoustical energy can be directed towards specific angles in such a way as to generate guided waves that are poorly energetic. By comparing the results using this new design to those obtained with a classical V(z) transducer, it is shown that the generation and detection of such waves is greatly improved, especially for poorly energetic waves that belong to a buried layer in a multilayered structure. This is especially seen on the components of the spectra of V(z). The modeling of the modified V(z) signature for a multi-element focused transducer is widely detailed first. Then, in order to illustrate the advantages of our proposed method, a three-layer structure (aluminum/epoxy/steel) is discussed. The interest of this method for the characterization of elastic properties of “buried” layers through specific guided waves that are detected with great difficulty—or even not at all—with a classical V(z) transducer is demonstrated, especially for the A0 and S0 modes corresponding to the steel layer inside the three-layer structure. In this study, we also develop a specific tracking method for particular guided waves possessing large phase velocity variations over the considered frequency range, as is the case for the S0 mode of the steel sub-layer.
{"title":"Enhancement of Guided Wave Detection and Measurement in Buried Layers of Multilayered Structures Using a New Design of V(z) Acoustic Transducers","authors":"M. Lematre, M. Lethiecq","doi":"10.3390/acoustics4040061","DOIUrl":"https://doi.org/10.3390/acoustics4040061","url":null,"abstract":"This paper presents the possibility of enhancement of the generation and detection of poorly energetic acoustic-guided waves in multilayered structures using a new design for a V(z) transducer. By defining a modified V(z) transducer composed of segmented piezoelectric elements, the acoustical energy can be directed towards specific angles in such a way as to generate guided waves that are poorly energetic. By comparing the results using this new design to those obtained with a classical V(z) transducer, it is shown that the generation and detection of such waves is greatly improved, especially for poorly energetic waves that belong to a buried layer in a multilayered structure. This is especially seen on the components of the spectra of V(z). The modeling of the modified V(z) signature for a multi-element focused transducer is widely detailed first. Then, in order to illustrate the advantages of our proposed method, a three-layer structure (aluminum/epoxy/steel) is discussed. The interest of this method for the characterization of elastic properties of “buried” layers through specific guided waves that are detected with great difficulty—or even not at all—with a classical V(z) transducer is demonstrated, especially for the A0 and S0 modes corresponding to the steel layer inside the three-layer structure. In this study, we also develop a specific tracking method for particular guided waves possessing large phase velocity variations over the considered frequency range, as is the case for the S0 mode of the steel sub-layer.","PeriodicalId":72045,"journal":{"name":"Acoustics (Basel, Switzerland)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47052345","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}
Pub Date : 2022-11-15DOI: 10.3390/acoustics4040059
K. Parker, M. Alonso
The free space solution to the wave equation in spherical coordinates is well known as a separable product of functions. Re-examination of these functions, particularly the sums of spherical Bessel and harmonic functions, reveals behaviors which can produce a range of useful beampatterns from radially symmetric sources. These functions can be modified by several key parameters which can be adjusted to produce a wide-ranging family of beampatterns, from the axicon Bessel beam to a variety of unique axial and lateral forms. We demonstrate that several special properties of the simple sum over integer orders of spherical Bessel functions, and then the sum of their product with spherical harmonic functions specifying the free space solution, lead to a family of useful beampatterns and a unique framework for designing them. Examples from a simulation of a pure tone 5 MHz ultrasound configuration demonstrate strong central axis concentration, and the ability to modulate or localize the axial intensity with simple adjustment of the integer orders and other key parameters related to the weights and arguments of the spherical Bessel functions.
{"title":"The Spherical Harmonic Family of Beampatterns","authors":"K. Parker, M. Alonso","doi":"10.3390/acoustics4040059","DOIUrl":"https://doi.org/10.3390/acoustics4040059","url":null,"abstract":"The free space solution to the wave equation in spherical coordinates is well known as a separable product of functions. Re-examination of these functions, particularly the sums of spherical Bessel and harmonic functions, reveals behaviors which can produce a range of useful beampatterns from radially symmetric sources. These functions can be modified by several key parameters which can be adjusted to produce a wide-ranging family of beampatterns, from the axicon Bessel beam to a variety of unique axial and lateral forms. We demonstrate that several special properties of the simple sum over integer orders of spherical Bessel functions, and then the sum of their product with spherical harmonic functions specifying the free space solution, lead to a family of useful beampatterns and a unique framework for designing them. Examples from a simulation of a pure tone 5 MHz ultrasound configuration demonstrate strong central axis concentration, and the ability to modulate or localize the axial intensity with simple adjustment of the integer orders and other key parameters related to the weights and arguments of the spherical Bessel functions.","PeriodicalId":72045,"journal":{"name":"Acoustics (Basel, Switzerland)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44828606","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}
Pub Date : 2022-11-11DOI: 10.3390/acoustics4040058
H. H. Dam, S. Nordholm
This paper proposes a new adaptive algorithm for the second-order blind signal separation (BSS) problem with convolutive mixtures by utilising a combination of an accelerated gradient and a conjugate gradient method. For each iteration of the adaptive algorithm, the search point and the search direction are obtained based on the current and the previous iterations. The algorithm efficiently calculates the step size for the accelerated conjugate gradient algorithm in each iteration. Simulation results show that the proposed accelerated conjugate gradient algorithm with optimal step size converges faster than the accelerated descent algorithm and the steepest descent algorithm with optimal step size while having lower computational complexity. In particular, the number of iterations required for convergence of the accelerated conjugate gradient algorithm is significantly lower than the accelerated descent algorithm and the steepest descent algorithm. In addition, the proposed system achieves improvement in terms of the signal to interference ratio and signal to noise ratio for the dominant speech outputs.
{"title":"Accelerated Conjugate Gradient for Second-Order Blind Signal Separation","authors":"H. H. Dam, S. Nordholm","doi":"10.3390/acoustics4040058","DOIUrl":"https://doi.org/10.3390/acoustics4040058","url":null,"abstract":"This paper proposes a new adaptive algorithm for the second-order blind signal separation (BSS) problem with convolutive mixtures by utilising a combination of an accelerated gradient and a conjugate gradient method. For each iteration of the adaptive algorithm, the search point and the search direction are obtained based on the current and the previous iterations. The algorithm efficiently calculates the step size for the accelerated conjugate gradient algorithm in each iteration. Simulation results show that the proposed accelerated conjugate gradient algorithm with optimal step size converges faster than the accelerated descent algorithm and the steepest descent algorithm with optimal step size while having lower computational complexity. In particular, the number of iterations required for convergence of the accelerated conjugate gradient algorithm is significantly lower than the accelerated descent algorithm and the steepest descent algorithm. In addition, the proposed system achieves improvement in terms of the signal to interference ratio and signal to noise ratio for the dominant speech outputs.","PeriodicalId":72045,"journal":{"name":"Acoustics (Basel, Switzerland)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46047089","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}
Pub Date : 2022-11-01DOI: 10.3390/acoustics4040057
A. Plăcintă, F. Borleanu, I. Moldovan, Alina Coman
Seismic velocity is the geophysical property that has a key role in characterizing dynamic processes and the state of the stress around the faults, providing valuable information regarding the change in the tectonic regime. The stress in the crust is an important indicator of the possible occurrence of a major earthquake, and the variation of seismic velocities, in time, can provide a clearer picture on the tectonic processes taking place in the region. In the crust, velocities change before, during, and after earthquakes through several mechanisms related to fault deformations, pore pressure, stress changes, and recovery processes. In this study, we investigate the possible correlation between the changes of seismic velocities (Vp/Vs) in time and the occurrence of moderate size crustal and intermediate depth earthquakes from the Vrancea region. Our findings show that there are no significant variations in Vp/Vs for the intermediate depth earthquakes, while crustal events have decreased seismic activity prior to the main earthquake and no high Vp/Vs anomalies. Our results indicate key aspects, and such analyses should be carried out in real-time to continuously explore any unusual pattern pointed out by the seismic velocity changes. Vp/Vs and their standard errors can also be used to describe seismic activity patterns that shape the tectonic evolution of the area.
{"title":"Correlation between Seismic Waves Velocity Changes and the Occurrence of Moderate Earthquakes at the Bending of the Eastern Carpathians (Vrancea)","authors":"A. Plăcintă, F. Borleanu, I. Moldovan, Alina Coman","doi":"10.3390/acoustics4040057","DOIUrl":"https://doi.org/10.3390/acoustics4040057","url":null,"abstract":"Seismic velocity is the geophysical property that has a key role in characterizing dynamic processes and the state of the stress around the faults, providing valuable information regarding the change in the tectonic regime. The stress in the crust is an important indicator of the possible occurrence of a major earthquake, and the variation of seismic velocities, in time, can provide a clearer picture on the tectonic processes taking place in the region. In the crust, velocities change before, during, and after earthquakes through several mechanisms related to fault deformations, pore pressure, stress changes, and recovery processes. In this study, we investigate the possible correlation between the changes of seismic velocities (Vp/Vs) in time and the occurrence of moderate size crustal and intermediate depth earthquakes from the Vrancea region. Our findings show that there are no significant variations in Vp/Vs for the intermediate depth earthquakes, while crustal events have decreased seismic activity prior to the main earthquake and no high Vp/Vs anomalies. Our results indicate key aspects, and such analyses should be carried out in real-time to continuously explore any unusual pattern pointed out by the seismic velocity changes. Vp/Vs and their standard errors can also be used to describe seismic activity patterns that shape the tectonic evolution of the area.","PeriodicalId":72045,"journal":{"name":"Acoustics (Basel, Switzerland)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49489178","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}
Pub Date : 2022-10-28DOI: 10.3390/acoustics4040056
J. Xi, M. Talaat, X. Si, Haibo Dong
Glottal vibration is fundamental to breathing-related disorders and respiratory sound generation. However, responses of the flow and acoustics to glottal vibrations of different frequencies are unclear. The objective of this study is to numerically evaluate the influences of glottal vibration frequencies on inspiratory airflow dynamics and flow-induced sound signals; this is different from normal phonation that is driven by controlled expiratory flows. A computational model was developed that comprised an image-based mouth–throat–lung model and a dynamic glottis expanding/contracting following a sinusoidal waveform. Large Eddy simulations were used to solve the temporal and spatial flow evolutions, and pressure signals were analyzed using different transform algorithms (wavelet, Hilbert, Fourier, etc.). Results show that glottal vibrations significantly altered the flows in the glottis and trachea, especially at high frequencies. With increasing vibration frequencies, the vortices decreased in scale and moved from the main flow to the walls. Phase shifts occurred between the glottis motion and glottal flow rates for all frequencies considered. Due to this phase shift, the pressure forces resisted the glottal motion in the first half of contraction/expansion and assisted the glottal motion in the second half of contraction/expansion. The magnitude of the glottal flow fluctuation was approximately linear with the vibration frequency (~f0), while the normal pressure force increased nonlinearly with the frequency (~f01.85). Instantaneous pressure signals were irregular at low vibration frequencies (10 and 20 Hz) but became more regular with increasing frequencies in the pressure profile, periodicity, and wavelet-transformed parameters. The acoustic characteristics specific to the glottal vibration frequency were explored in temporal and frequency domains, which may be used individually or as a combination in diagnosing vocal fold dysfunction, snoring, sleep apnea, or other breathing-related diseases.
{"title":"Flow Dynamics and Acoustics from Glottal Vibrations at Different Frequencies","authors":"J. Xi, M. Talaat, X. Si, Haibo Dong","doi":"10.3390/acoustics4040056","DOIUrl":"https://doi.org/10.3390/acoustics4040056","url":null,"abstract":"Glottal vibration is fundamental to breathing-related disorders and respiratory sound generation. However, responses of the flow and acoustics to glottal vibrations of different frequencies are unclear. The objective of this study is to numerically evaluate the influences of glottal vibration frequencies on inspiratory airflow dynamics and flow-induced sound signals; this is different from normal phonation that is driven by controlled expiratory flows. A computational model was developed that comprised an image-based mouth–throat–lung model and a dynamic glottis expanding/contracting following a sinusoidal waveform. Large Eddy simulations were used to solve the temporal and spatial flow evolutions, and pressure signals were analyzed using different transform algorithms (wavelet, Hilbert, Fourier, etc.). Results show that glottal vibrations significantly altered the flows in the glottis and trachea, especially at high frequencies. With increasing vibration frequencies, the vortices decreased in scale and moved from the main flow to the walls. Phase shifts occurred between the glottis motion and glottal flow rates for all frequencies considered. Due to this phase shift, the pressure forces resisted the glottal motion in the first half of contraction/expansion and assisted the glottal motion in the second half of contraction/expansion. The magnitude of the glottal flow fluctuation was approximately linear with the vibration frequency (~f0), while the normal pressure force increased nonlinearly with the frequency (~f01.85). Instantaneous pressure signals were irregular at low vibration frequencies (10 and 20 Hz) but became more regular with increasing frequencies in the pressure profile, periodicity, and wavelet-transformed parameters. The acoustic characteristics specific to the glottal vibration frequency were explored in temporal and frequency domains, which may be used individually or as a combination in diagnosing vocal fold dysfunction, snoring, sleep apnea, or other breathing-related diseases.","PeriodicalId":72045,"journal":{"name":"Acoustics (Basel, Switzerland)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43499171","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}
Pub Date : 2022-10-21DOI: 10.3390/acoustics4040055
N. Kanev
Metasurfaces formed by monopole and dipole resonators are studied theoretically. The monopole resonators are Helmholtz resonators or membranes vibrating on the first eigenfrequency; the dipole ones are spheres on springs or membranes vibrating on the second eigenfrequency. It is shown that acoustic properties of the metasurface formed by the built-in monopole resonators can be described by an equivalent impedance, which characterizes a normal forcing to the surface, whereas this impedance is not suitable for the metasurface formed by the dipole resonators, because motion of the metasurface is excited by a forcing tangential to the surface. For such boundaries, a new characteristic named “tangential impedance” is proposed. This is a ratio of the second derivative of the sound pressure along a coordinate tangential to the boundary to the normal velocity of the boundary. The dipole metasurface can be described by the equivalent tangential impedance. Reflection and absorption coefficients of the surface with the tangential impedance are found for a harmonic plane wave in dependance of an incidence angle. It is found that the angular dependences of the coefficients are very different for the monopole and dipole metasurfaces.
{"title":"Resonant Metasurfaces with a Tangential Impedance","authors":"N. Kanev","doi":"10.3390/acoustics4040055","DOIUrl":"https://doi.org/10.3390/acoustics4040055","url":null,"abstract":"Metasurfaces formed by monopole and dipole resonators are studied theoretically. The monopole resonators are Helmholtz resonators or membranes vibrating on the first eigenfrequency; the dipole ones are spheres on springs or membranes vibrating on the second eigenfrequency. It is shown that acoustic properties of the metasurface formed by the built-in monopole resonators can be described by an equivalent impedance, which characterizes a normal forcing to the surface, whereas this impedance is not suitable for the metasurface formed by the dipole resonators, because motion of the metasurface is excited by a forcing tangential to the surface. For such boundaries, a new characteristic named “tangential impedance” is proposed. This is a ratio of the second derivative of the sound pressure along a coordinate tangential to the boundary to the normal velocity of the boundary. The dipole metasurface can be described by the equivalent tangential impedance. Reflection and absorption coefficients of the surface with the tangential impedance are found for a harmonic plane wave in dependance of an incidence angle. It is found that the angular dependences of the coefficients are very different for the monopole and dipole metasurfaces.","PeriodicalId":72045,"journal":{"name":"Acoustics (Basel, Switzerland)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44111407","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}
Pub Date : 2022-10-17DOI: 10.3390/acoustics4040054
N. Mikhailova, I. Smirnov, B. Yakupov
In engineering problems associated with acoustic wave propagation in a liquid, cavitation onset could be an adverse phenomenon, or, conversely, a required process. In both cases, knowledge of the ultrasonic parameters that lead to cavitation onset under given external conditions is relevant and necessary for solving both fundamental and practical problems. The present work proposes experimental results of studying the threshold of acoustic cavitation, which was implemented at different ultrasound frequencies with a change in external pressure, power of transducer and temperature of the liquid. The experiments were carried out for sunflower oil. The test findings demonstrated how the cavitation threshold changes with varying the power of ultrasound exposure in time. In addition, the effect of external pressure fluctuations on cavitation onset was investigated. The obtained results contribute to the understanding of cavitation processes and could be necessary for verification of theoretical models.
{"title":"Experimental Study of the Acoustic Cavitation Threshold in Sunflower Oil Depending on Different Impact Regime","authors":"N. Mikhailova, I. Smirnov, B. Yakupov","doi":"10.3390/acoustics4040054","DOIUrl":"https://doi.org/10.3390/acoustics4040054","url":null,"abstract":"In engineering problems associated with acoustic wave propagation in a liquid, cavitation onset could be an adverse phenomenon, or, conversely, a required process. In both cases, knowledge of the ultrasonic parameters that lead to cavitation onset under given external conditions is relevant and necessary for solving both fundamental and practical problems. The present work proposes experimental results of studying the threshold of acoustic cavitation, which was implemented at different ultrasound frequencies with a change in external pressure, power of transducer and temperature of the liquid. The experiments were carried out for sunflower oil. The test findings demonstrated how the cavitation threshold changes with varying the power of ultrasound exposure in time. In addition, the effect of external pressure fluctuations on cavitation onset was investigated. The obtained results contribute to the understanding of cavitation processes and could be necessary for verification of theoretical models.","PeriodicalId":72045,"journal":{"name":"Acoustics (Basel, Switzerland)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44302179","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}
Pub Date : 2022-10-05DOI: 10.3390/acoustics4040052
K. Stampka, E. Sarradj
To model the vibration and structure-borne sound excitation and propagation of a railway rail, it can be modeled as an infinite beam on an elastic foundation. Existing analytical or numerical models are either formulated in the frequency domain or consider only finite beams in the time domain. Therefore, a time-domain approach for bending wave propagation on an effectively infinite beam on an elastic foundation is proposed. The approach makes use of an implicit finite-difference method that allows for varying properties of the beam and the foundation along the length of the beam. Strategies for an efficient discretization are discussed. The method is validated against existing analytical models for a single layer and two layers, as well as continuous and discrete support. The results show very good agreement, and it can be concluded that the proposed method can be seen as a versatile method for simulating the behavior of a beam on different kinds of elastic foundations.
{"title":"A Time-Domain Finite-Difference Method for Bending Waves on Infinite Beams on an Elastic Foundation","authors":"K. Stampka, E. Sarradj","doi":"10.3390/acoustics4040052","DOIUrl":"https://doi.org/10.3390/acoustics4040052","url":null,"abstract":"To model the vibration and structure-borne sound excitation and propagation of a railway rail, it can be modeled as an infinite beam on an elastic foundation. Existing analytical or numerical models are either formulated in the frequency domain or consider only finite beams in the time domain. Therefore, a time-domain approach for bending wave propagation on an effectively infinite beam on an elastic foundation is proposed. The approach makes use of an implicit finite-difference method that allows for varying properties of the beam and the foundation along the length of the beam. Strategies for an efficient discretization are discussed. The method is validated against existing analytical models for a single layer and two layers, as well as continuous and discrete support. The results show very good agreement, and it can be concluded that the proposed method can be seen as a versatile method for simulating the behavior of a beam on different kinds of elastic foundations.","PeriodicalId":72045,"journal":{"name":"Acoustics (Basel, Switzerland)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47272460","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}
Pub Date : 2022-10-01DOI: 10.3390/acoustics4040051
Manuel Brandner, M. Frank, A. Sontacchi
Singing voice directivity for five sustained German vowels /a:/, /e:/, /i:/, /o:/, /u:/ over a wide pitch range was investigated using a multichannel microphone array with high spatial resolution along the horizontal and vertical axes. A newly created dataset allows to examine voice directivity in classical singing with high resolution in angle and frequency. Three voice production modes (phonation modes) modal, breathy, and pressed that could affect the used mouth opening and voice directivity were investigated. We present detailed results for singing voice directivity and introduce metrics to discuss the differences of complex voice directivity patterns of the whole data in a more compact form. Differences were found between vowels, pitch, and gender (voice types with corresponding vocal range). Differences between the vowels /a:, e:, i:/ and /o:, u:/ and pitch can be addressed by simplified metrics up to about d2/D5/587 Hz, but we found that voice directivity generally depends strongly on pitch. Minor differences were found between voice production modes and found to be more pronounced for female singers. Voice directivity differs at low pitch between vowels with front vowels being most directional. We found that which of the front vowels is most directional depends on the evaluated pitch. This seems to be related to the complex radiation pattern of the human voice, which involves a large inter-subjective variability strongly influenced by the shape of the torso, head, and mouth. All recorded classical sung vowels at high pitches exhibit similar high directionality.
{"title":"Horizontal and Vertical Voice Directivity Characteristics of Sung Vowels in Classical Singing","authors":"Manuel Brandner, M. Frank, A. Sontacchi","doi":"10.3390/acoustics4040051","DOIUrl":"https://doi.org/10.3390/acoustics4040051","url":null,"abstract":"Singing voice directivity for five sustained German vowels /a:/, /e:/, /i:/, /o:/, /u:/ over a wide pitch range was investigated using a multichannel microphone array with high spatial resolution along the horizontal and vertical axes. A newly created dataset allows to examine voice directivity in classical singing with high resolution in angle and frequency. Three voice production modes (phonation modes) modal, breathy, and pressed that could affect the used mouth opening and voice directivity were investigated. We present detailed results for singing voice directivity and introduce metrics to discuss the differences of complex voice directivity patterns of the whole data in a more compact form. Differences were found between vowels, pitch, and gender (voice types with corresponding vocal range). Differences between the vowels /a:, e:, i:/ and /o:, u:/ and pitch can be addressed by simplified metrics up to about d2/D5/587 Hz, but we found that voice directivity generally depends strongly on pitch. Minor differences were found between voice production modes and found to be more pronounced for female singers. Voice directivity differs at low pitch between vowels with front vowels being most directional. We found that which of the front vowels is most directional depends on the evaluated pitch. This seems to be related to the complex radiation pattern of the human voice, which involves a large inter-subjective variability strongly influenced by the shape of the torso, head, and mouth. All recorded classical sung vowels at high pitches exhibit similar high directionality.","PeriodicalId":72045,"journal":{"name":"Acoustics (Basel, Switzerland)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46900643","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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