Direction Of Sound Propagation Research Articles

Simulation and experiment of complex residual stress detection of metal plate based on critical refracted longitudinal wave (LCR) method

This study is based on the principles of acoustoelasticity, analyzing the variation in sound wave time-of-flight(TOF) under different conditions using the critical refracted longitudinal(LCR) wave method. A simulation model was developed using the COMSOL finite element simulation software to mimic the propagation of LCR wave in a stress-free plate. The model was then subjected to uniaxial loading, and the change in wave TOF was observed by varying the angle between the stress direction and the sound wave propagation direction under constant load. The results were compared with theoretical calculations, showing a high degree of agreement, validating the accuracy of the designed model. Subsequently, during the tensile testing, the influence of different uniaxial loads and angle variations on the TOF of LCR wave was observed. Upon comparing the experiment data with theoretical calculations, a high degree of consistency in the trend of variation is observed, this demonstrates that the detection platform established in this study is feasible for the assessment of residual stresses in practice.

WEA-Acceptance Data—A Dataset of Acoustic, Meteorological, and Operational Wind Turbine Measurements

In this article, a dataset is described which combines wind turbine supervisory control and data acquisition (SCADA), meteorological and acoustical data and thus gives a detailed description of a wind farm and its atmospheric and acoustic environment. The data were collected during different seasons for several weeks at a time, such that a multitude of environmental and operational conditions are covered. In five measurement campaigns, in total three different locations with similar surroundings were captured. The raw data were enhanced with derived values such as atmospheric stability or direction of sound propagation. Data of one month including all time series measurements as well as monophonic audio recordings are now published. The dataset also contains three exemplary use cases along with documents that describe the data pre-processing.

Analysis of the Anisotropy of Sound Propagation Velocity in Thin Wooden Plates Using Lamb Waves.

The objective of the study was to analyze the influence of coating treatments on sound propagation speeds in thin boards, along the longitudinal and radial directions of resonance wood. The samples studied were thin boards made of spruce and maple wood with dimensions of 240 mm × 80 mm × 4 mm (length × width × thickness) subjected to different coating treatments (oil-based varnish and alcohol varnish) as well as unvarnished samples, exposed to radiation UV, and specimens treated in the saline fog. The test method consisted of evaluating the propagation speeds of Lamb waves applied to thin plates, according to a semicircular test model, so that the results highlighted both the acoustic response in the longitudinal and radial directions as well as the variation in the anisotropy of the samples with the change in the sound propagation direction relative to wood fibers. Based on the statistical analysis, sound propagation speed profiles were obtained in each of the 38 directions analyzed for all wood samples. The results highlighted that the oil-based varnish led to a decrease in the speed of propagation in the radial direction, compared to the alcoholic varnish, whose major effect was in the longitudinal direction, on the spruce wood. On maple wood, increasing the number of varnish layers, regardless of the type of varnish, led to a decrease in the anisotropy ratio between the longitudinal and radial directions.

Development of a high-performance cymbal vector hydrophone

Detecting the direction of sound wave propagation using conventional acoustic hydrophones can be challenging, as they are omnidirectional and only measure the magnitude of sound pressure. However, vector hydrophones offer a solution to this problem, which enables the determination of both magnitude and direction of sound waves. In this study, we propose a novel structure for a vector hydrophone that consists of two cymbal transducers attached to a hollow cylindrical frame, positioned facing each other. Initially, we analyze the received voltage sensitivity of the two cymbal transducers and evaluate the suitability of the structure as a vector hydrophone by implementing a dipole mode beam pattern. Furthermore, we investigate the impact of structural parameters on the performance of the vector hydrophone. Based on these findings, we derive the optimal structure for the vector hydrophone, maximizing its sensitivity. Finally, we validate the design by manufacturing a prototype of the cymbal vector hydrophones and comparing their measured performance with the calculated values.

Inverse design of acoustic coatings using Bayesian inference

A Bayesian approach for the inverse design of acoustic coatings for underwater noise control is presented. The coating model comprises a periodic arrangement of voids embedded in a soft viscoelastic material. The viscoelastic material is attached to a steel backing with water on its incidence side and air on its transmission side. The acoustic performance of the coating is strongly dependent on the geometric properties of the voided inclusions as well as the number of layers of voids in the direction of sound propagation. The geometric optimization process using Bayesian inference proceeds inversely from a target absorption coefficient spectrum to the required number of voided layers, the geometric design parameters in each layer, and the distance between each layer. The Bayesian design process demonstrates that broadband sound absorption can be achieved using a multilayered coating with a gradient change in both void diameter and distance between each layer. Optimized designs using the Bayesian approach are validated against results obtained numerically as well as experimental results from the literature.

Rapid and Efficient Computation of Cell Paths During Ultrasonic Focusing.

This biophysical analysis explores the first-principles physics of movement of white blood cell sized particles, suspended in an aqueous fluid and experiencing progressive or standing waves of acoustic pressure. In many current applications the cells are gradually nudged or herded toward the nodes of the standing wave, providing a degree of acoustic focusing and concentration of the cells in layers perpendicular to the direction of sound propagation. Here the underlying biomechanics of this phenomenon are analyzed specifically for the viscous regime of water and for small diameter microscopic spheroids such as living cells. The resulting mathematical model leads to a single algebraic expression for the creep or drift velocity as a function of sound frequency, amplitude, wavelength, fluid viscosity, boundary dimensions, and boundary reflectivity. This expression can be integrated numerically by a simple and fast computer algorithm to demonstrate net movement of particles as a function of time, providing a guide to optimization in a variety of emerging applications of ultrasonic cell focusing.

Defect‐Free Sound Insulator Using Single Metal‐Based Friction Stir Process Array

Metals are excellent conductors for phonon transportation such as vibration, sound, and heat. Generally, metal sound insulators require multimaterial structure or defects and unimetal sound insulators are challenging. Therefore, a design of a defect‐free sound insulator made by single alloys with multiple friction stir processes (FSPs) is proposed. Periodic friction stir processing can induce superlattice‐like local mechanical properties’ modifications. By experimental acoustic characterization, it is observed that FSP can introduce clear acoustic–elastic property contrast on an aluminum plate by the presence of stir zone and heat‐affected zones. In numerical simulations, the signature FSP‐induced property profile is periodically and parallelly arranged on a long aluminum plate. The transmission gap frequencies are present on the frequency spectrum with the sound propagation direction perpendicular to the FSP paths. Disorder offsets on FSP periodicity are further introduced. Anderson localization is found on a resonance frequency, which provides −11 dB sound reduction by an exponential decay. Due to the finite design length, the slight disorder can also enhance sound insulation in the periodic transmission gap frequency. With analysis and comparison with different configurations, the best performance in the models can achieve −30 dB sound insulation in the 350 mm‐long aluminum alloy plate with 14 parallel FSPs.

A new base of wind turbine noise measurement data and its application for a systematic validation of sound propagation models

Abstract. Extensive measurements in the area of wind turbines were performed in order to validate a sound propagation model which is based on the Crank–Nicolson parabolic equation method. The measurements were carried out over a flat grass-covered landscape and under various environmental conditions. During the measurements, meteorological and wind turbine performance data were acquired and acoustical data sets were recorded at distances of 178, 535 and 845 m from the wind turbine. By processing and analysing the measurement data, validation cases and input parameters for the sound propagation model were derived. The validation includes five groups that are characterised by different sound propagation directions, i.e. downwind, crosswind and upwind conditions in varying strength. In strong upwind situations, the sound pressure levels at larger distances are overestimated because turbulence is not considered in the modelling. In the other directions, the model reproduces the measured sound propagation losses well in the overall sound pressure level and in the third octave band spectra. As in the recorded measurements, frequency-dependent maxima and minima are identified, and losses generally increase with increasing distance and frequency. The agreement between measured and modelled sound propagation losses decreases with distance. The data sets used in the validation are freely accessible for further research.

Accelerometer intensity vector sensor network for environmental noise monitoring with source direction and location

AIVS (Accelerometer-based Intensity Vector Sensors, /āvs/) represent a new way to measure 3-d sound and are designed to integrate into existing noise monitoring solutions. Standard microphones measure sound pressure, which cannot alone deduce the direction of sound propagation. AIVS is based on the measurement of the velocity of a small parcel of air surrounding a triaxial accelerometer, from which a vector-based representation of sound intensity is calculated. AIVS integrates a MEMS triaxial accelerometer with one MEMS microphone and synchronously measures particle velocity and pressure, resulting in a 3-d intensity vector at each AIVS node. An AIVS network is synchronized to GNSS time and sensors are deployed in groups surrounding and/or within a local measurement site. Low power AIVS nodes are location-aware and estimate azimuth and elevation angles to detected noise sources as a function of frequency. Range to source is computed when noise events are observed from multiple nodes. AIVS nodes are managed by a Raspberry-PI (RPI) sensor hub in a wired CAN-bus supporting distances up to 100 m, or via the Bluetooth Low Energy (BLE) protocol. More widely separated nodes are joined through WWLAN technologies via the local RPI hub.

Amplitude Matching for Multizone Sound Field Control

A multizone sound field control method, called amplitude matching, is proposed. The objective of amplitude matching is to synthesize a desired amplitude (or magnitude) distribution over a target region with multiple loudspeakers, whereas the phase distribution is arbitrary. Most of the current multizone sound field control methods are intended to synthesize a specific sound field including phase or to control acoustic potential energy inside the target region. In amplitude matching, a specific desired amplitude distribution can be set, ignoring sound propagation directions. Although the optimization problem of amplitude matching does not have a closed-form solution, our proposed algorithm based on the alternating direction method of multipliers (ADMM) allows us to accurately and efficiently synthesize the desired amplitude distribution. We also introduce the differential-norm penalty for a time-domain filter design with a small filter length. The experimental results indicated that the proposed method outperforms current multizone sound field control methods in terms of accuracy of the synthesized amplitude distribution.

Emergent anisotropy in the Fulde–Ferrell–Larkin–Ovchinnikov state

Exotic superconductivity is formed by unconventional electron pairing and exhibits various unique properties that cannot be explained by the basic theory. The Fulde–Ferrell–Larkin–Ovchinnikov (FFLO) state is known as an exotic superconducting state in that the electron pairs have a finite center-of-mass momentum leading to a spatially modulated pattern of superconductivity. The spatial modulation endows the FFLO state with emergent anisotropy. However, the anisotropy has never been experimentally verified despite numerous efforts over the years. Here, we report detection of anisotropic acoustic responses depending on the sound propagation direction appearing above the Pauli limit. This anisotropy reveals that the two-dimensional FFLO state has a center-of-mass momentum parallel to the nesting vector on the Fermi surface. The present findings will facilitate our understanding of not only superconductivity in solids but also exotic pairings of various particles.

Influence of Magnetic Field on Sound Transmission Loss of the Unit Filled with Magnetorheological Fluid.

To explore the feasibility of applying magnetorheological fluids (MRFs) in the field of noise control, the influence of the magnetic field intensity and direction on the sound transmission loss (STL) of a unit filled with MRF (MRF unit) were investigated in this study. First, two types of test sample containing the MRF unit were designed and fabricated. The magnetic field applied to the MRF was provided by the permanent magnets used in pairs. The direction of the magnetic field was perpendicular or parallel to the direction of the sound wave propagation. The distribution of the magnetic field intensity of the two types of test samples was simulated using magnetostatic finite element analysis and validated with the magnetic field intensity measured using a Teslameter. For comparison, test samples containing air and water units were also prepared. Then, the STL of the two types of test samples were measured under different magnetic field intensities using the impedance tube method. Finally, the STL curves of the two types of test samples were presented, and the influence of magnetic field intensity and direction on the STL were discussed. The results demonstrate that the magnetic field direction has a significant influence on the STL of the MRF unit. In addition, when the magnetic field direction is parallel to the sound propagation direction, the STL of the test sample containing MRF unit significantly increases with the increase of the magnetic field intensity at low and middle frequencies.

Erratum: Pseudogauge field driven acoustoelectric current in two-dimensional hexagonal Dirac materials [Phys. Rev. B 105 , 125407 (2022)

Using a diagrammatic scheme, we study the acoustoelectric effects in two-dimensional (2D) hexagonal Dirac materials due to the sound-induced pseudo-gauge field. We analyze both uniform and {\em spatially dispersive} currents in response to copropagating and counterpropagating sound waves, respectively. In addition to the longitudinal acoustoelectric current, we obtain an exotic {\em transverse} charge current flowing perpendicular to the sound propagation direction owing to the interplay of transverse and longitudinal gauge field components $j_T\propto A_L A^\ast_T$. In contrast to the almost isotropic directional profile of the longitudinal uniform current, a highly anisotropic transverse component $j_T\sim\sin(6\theta)$ is achieved that stems from the inherited three-fold symmetry of the hexagonal lattice. However, both longitudinal and transverse parts of the dispersive current are predicted to be strongly anisotropic $\sim\sin^2(3\theta)$ or $\cos^2(3\theta)$. We quantitatively estimate the pseudogauge field contribution to the acoustoelectric current that can be probed in future experiments in graphene and other 2D hexagonal Dirac materials.

The acoustic streaming effects of sonic black hole

In this paper, the acoustic streaming effects of Sonic Black Hole (SBH) are deeply studied by using the numerical and simulation method. By solving Navier–Stokes equations of compressible fluid, we analyze the flow characteristics of acoustic medium in SBH excited by sound wave, and further discuss the acoustic streaming effects and sound wave capture mechanism of SBH. The phenomenon of simultaneous reduction of medium and high-frequency sound reflection and transmission is analyzed. Under the excitation of medium- and high-frequency sound waves, the interaction between fluid medium flow and SBH structure leads to the uneven internal velocity distribution in the sound propagation direction, which can lead to the phenomenon of sound wave capture and deceleration. For low-frequency sound waves, the velocity distribution of sound medium is uniform, and there is almost no change in velocity gradient, resulting in the uniform distribution of sound pressure without sound absorption. These theoretical and numerical results are in good agreement with the experimental results in the literature, and also verify our results. Finally, by improving the structure, increasing the complexity of sound medium flow and the gradient change in the direction of sound propagation, the sound absorption and insulation ability of the SBH can be further improved. This study reveals the sound transmission mechanism of SBH, which can provide a new idea for the suppression of low-frequency sound waves in SBH.

Pseudogauge field driven acoustoelectric current in two-dimensional hexagonal Dirac materials

Using a diagrammatic scheme, we study the acoustoelectric effects in two-dimensional (2D) hexagonal Dirac materials due to the sound-induced pseudogauge field. We analyze both uniform and spatially dispersive currents in response to copropagating and counterpropagating sound waves, respectively. In addition to the longitudinal acoustoelectric current, we obtain an exotic transverse charge current flowing perpendicular to the sound propagation direction owing to the interplay of transverse and longitudinal gauge field components ${j}_{T}\ensuremath{\propto}{A}_{L}{A}_{T}^{*}$. In contrast to the almost isotropic directional profile of the longitudinal uniform current, a highly anisotropic transverse component ${j}_{T}\ensuremath{\sim}sin(6\ensuremath{\theta})$ is achieved that stems from the inherited threefold symmetry of the hexagonal lattice. However, both longitudinal and transverse parts of the dispersive current are predicted to be strongly anisotropic $\ensuremath{\sim}{sin}^{2}(3\ensuremath{\theta})$ or ${cos}^{2}(3\ensuremath{\theta})$. We quantitatively estimate the pseudogauge field contribution to the acoustoelectric current that can be probed in future experiments in graphene and other 2D hexagonal Dirac materials.

Sound absorption by a metasurface comprising hard spheres in a soft medium.

We present a theoretical framework for acoustic wave propagation in a metasurface comprising a hexagonal lattice of hard spherical inclusions embedded in a soft elastic medium. Each layer of inclusions in the direction of sound propagation is approximated as a homogenized layer with effective geometric and material properties. To account for multiple scattering effects in the lattice of resonant inclusions, an analogy between the fluid dynamics of creeping flows and elastodynamics of soft materials is implemented. Results obtained analytically are in excellent agreement with numerical simulations that exactly model the geometric and material properties of the metasurface.

Anomaly-induced sound absorption in Weyl semimetals

Topology of Weyl semimetals affects sound attenuation in these materials. Most notably, the existence of Berry monopoles associated with linear band crossings leads to the existence of acoustic magnetochiral dichroism: sound attenuation is different for opposite directions of sound propagation. The effect is within reach of current experimental techniques, and, importantly, is of quantum mechanical origin. This should help its detection in available compounds.

Acoustogalvanic Effect in Dirac and Weyl Semimetals.

The acoustogalvanic effect is proposed as a nonlinear mechanism to generate a direct electric current by passing acoustic waves in Dirac and Weyl semimetals. Unlike the standard acoustoelectric effect, which relies on the sound-induced deformation potential and the corresponding electric field, the acoustogalvanic one originates from the pseudoelectromagnetic fields, which are not subject to screening. The longitudinal acoustogalvanic current scales at least quadratically with the relaxation time, which is in contrast to the photogalvanic current where the scaling is linear. Because of the interplay of pseudoelectric and pseudomagnetic fields, the current could show a nontrivial dependence on the direction of sound wave propagation. Being within the experimental reach, the effect can be utilized to probe dynamical deformations and corresponding pseudoelectromagnetic fields, which are yet to be experimentally observed in Weyl and Dirac semimetals.

Anomalous Lattice Softening Near a Quantum Critical Point in a Transverse Ising Magnet.

We have investigated the elastic response of a transverse Ising magnet CoNb_{2}O_{6} by means of ultrasound velocity measurement. A huge elastic anomaly in the C_{66} mode is observed near a quantum critical point when sweeping a magnetic field perpendicular to the Ising axis. This anomaly appears to become critical only for the Faraday configuration (field parallel to the sound propagation direction) but is much less pronounced for the Voigt geometry (field perpendicular to the sound propagation direction). We propose that the relativistic spin-orbit interaction plays a crucial role in the quantum critical regime resulting in the elastic anomaly, which is enhanced by quantum fluctuations.

Dependence of skull surface wave propagation on stimulation sites and direction under bone conduction.

In order to better understand bone conduction sound propagation across the skull, three-dimensional (3D) wave propagation on the skull surface was studied, along with its dependence on stimulation direction and location of a bone conduction hearing aid (BCHA) actuator. Experiments were conducted on five Thiel embalmed whole head cadaver specimens. Stimulation, in the 0.1-10 kHz range, was sequentially applied at the forehead and mastoid via electromagnetic actuators from commercial BCHAs, supported by a 5-N steel band. The head response was quantified by sequentially measuring the 3D motion of ∼200 points (∼15-20 mm pitch) across the ipsilateral, top, and contralateral skull surface via a 3D laser Doppler vibrometer (LDV) system, guided by a robotic positioner. Low-frequency stimulation (<1 kHz) resulted in a spatially complex rigid-body-like motion of the skull that depended on both the stimulation condition and head support. The predominant motion direction was only 5-10 dB higher than other components below 1 kHz, with no predominance at higher frequencies. Sound propagation direction across the parietal plates did not coincide with stimulation location, potentially due to the head base and forehead remaining rigid-like at higher frequencies and acting as a large source for the deformation patterns across the parietal sections.