Interaction Of Sound Waves Research Articles

Assessment of angular distribution of sound scattering in enclosures

This study proposes an approach for quantitatively assessing sound scattering degrees caused by objects within enclosures. It categorizes the high-frequency sound fields in rooms into two distinct components: (1) specular reflections arising from boundary surfaces, and (2) non-specular scattering contributed by objects (interiors). To achieve this, sound fields sampled on a sphere for two scenarios, with and without interiors, were decomposed into plane waves. The coherence between the impulse responses of these plane waves for these two scenarios is analyzed to obtain the proportion of specular and non-specular components within the room containing interiors. Derived from these coherence curves, the Equivalent Scattering Coefficients (ESCs) quantify the degree of scattering distributed across various directions, reflecting the interaction of sound waves with these interior elements. The extracted ESCs facilitate to quantification of the proportion of specular and non-specular components, which can be efficiently modeled separately and combined in a hybrid acoustic model, offering significant potential for sound field reconstruction.

Frequency shift of parametric sound by face-to-face pair of sources in relative motion.

This paper reports an acoustic phenomenon regarding a parametric sound source (also referred to as a parametric array): a secondary sound wave is generated from the nonlinear interaction of multiple primary sound waves with varied frequency components, particularly when two relatively moving sound sources face each other. It was found that the frequency of the secondary wave fluctuated according to the source movement and provided a theoretical explanation for this phenomenon. It is experimentally demonstrated that this frequency shift was approximately proportional to the velocity of the moving source toward the fixed source and to the driving frequency of the moving source. This phenomenon has much in common with the Doppler's effect, but its unique property is that the frequency shift depends on neither the observation position nor the source velocity toward the observer. These sound generation principles enable measurement of the velocity of slowly moving sound sources while maintaining a low-modulation frequency band and a short measurement time. This phenomenon can potentially be applied to an alternative approach for acoustic noncontact velocimetry of moving objects.

Acoustic cavitation for agri-food applications: Mechanism of action, design of new systems, challenges and strategies for scale-up

Acoustic cavitation, an intriguing phenomenon resulting from the interaction of sound waves with a liquid medium, has emerged as a promising avenue in agri-food processing, offering opportunities to enhance established processes improving primary production of ingredients and further food processing. This comprehensive review provides an in-depth analysis of the mechanisms, design considerations, challenges and scale-up strategies associated with acoustic cavitation for agri-food applications. The paper starts by elucidating the fundamental principles of acoustic cavitation and its measurement, delving then into the diverse effects of different parameters associated with, the acoustic wave, mechanical design and operation of the ultrasonic system, along with those related to the food matrix. The technological advancements achieved in the design and set-up of ultrasonic reactors addressing limitations during scale up are also discussed. The design, engineering and mathematical modelling of ultrasonic equipment tailored for agri-food applications are explored, along with strategies to maximize cavitation intensity and efficiency in the application of brining, freezing, drying, emulsification, filtration and extraction. Advanced US equipment, such as multi-transducers (tubular resonator, FLOW:WAVE®) and larger processing surface areas through innovative designing (Barbell horn, CascatrodesTM), are one of the most promising strategies to ensure consistency of US operations at industrial scale. This review paper aims to provide valuable insights into harnessing acoustic cavitation's potential for up-scaling applications in food processing via critical examination of current research and advancements, while identifying future directions and opportunities for further research and innovation.

Hirota bilinear method and multi-soliton interaction of electrostatic waves driven by cubic nonlinearity in pair-ion–electron plasmas

Multi-soliton interaction of nonlinear ion sound waves in a pair-ion–electron (PIE) plasma having non-Maxwellian electrons including Kappa, Cairns, and generalized two spectral index distribution functions is studied. To this end, a modified Korteweg–de Vries (mKdV) equation is obtained to investigate the ion-acoustic waves in a PIE plasma at a critical plasma composition. The effects of temperature and density ratios and the non-Maxwellian electron velocity distributions on the overtaking interaction of solitons are explored in detail. The results reveal that both hump (positive peak) and dip (negative peak) solitons can propagate for the physical model under consideration. Two and three-soliton interactions are presented, and the novel features of interacting compressive and rarefactive solitons are highlighted. The present investigation may be useful in laboratory plasmas where PIE plasmas have been reported.

Review on Wearable System for Positioning Ultrasound Scanner

Although ultrasound (US) scan or diagnosis became widely employed in the 20th century, it still plays a crucial part in modern medical diagnostics, serving as a diagnostic tool or a therapy process guide. This review provides information on current wearable technologies and applications used in external ultrasound scanning. It offers thorough explanations that could help build upon any project utilizing wearable external US devices. It touches on several aspects of US scanning and reviews basic medical procedure concepts. The paper starts with a detailed overview of ultrasound principles, including the propagation speed of sound waves, sound wave interactions, image resolution, transducers, and probe positioning. After that, it explores wearable external US mounts and wearable external US transducers applied for sonograph purposes. The subsequent section tackles artificial intelligence methods in wearable US scanners. Finally, future external US scan directions are reported, focusing on hardware and software.

Ultrasonic methods for determining flows and velocity fields

This paper introduces research and development of a modern non-invasive device for determining flows and velocity fields. This device is based on the ultrasonic method. The measured fluid flow is surrounded by appropriate ultrasonic transmitters and receivers, which communicate with each other. A physical principle of this method consists in an interaction of sound waves with a flow, which generates a certain delay in sound waves transmission. The found quantity is thus time delay. The device is being designed as a flowmeter and with advanced and extended postprocessing as a tomograph, which reconstructs a 3D vector field for big volumes. This whole process requires the following: development of an appropriate design of the ultrasonic flowmeter and tomograph, testing the signal transfer and also various postprocessing methods on a measurement accuracy, building of a special verification experimental equipment and building of an electronic device as a control unit and data acquisition system.

Economical Sponge Phantom for Teaching, Understanding, and Researching A- and B-Line Reverberation Artifacts in Lung Ultrasound.

This project evaluated a low-cost sponge phantom setup for its capability to teach and study A- and B-line reverberation artifacts known from lung ultrasound and to numerically simulate sound wave interaction with the phantom using a finite-difference time-domain (FDTD) model. Both A- and B-line artifacts were reproducible on B-mode ultrasound imaging as well as in the FDTD-based simulation. The phantom was found to be an easy-to-set up and economical tool for understanding, teaching, and researching A- and B-line artifacts occurring in lung ultrasound. The FDTD method-based simulation was able to reproduce the artifacts and provides intuitive insight into the underlying physics.

Sound absorption and reflection from a resonant metasurface: Homogenisation model with experimental validation

Efficient manipulation of sound waves by some resonant acoustic metasurface designs has recently been reported in the literature. This paper presents a general theoretical framework for the description of sound wave interaction with the resonant metasurface that is independent of the nature of resonators and the excitation. The equations governing the behaviour of the metasurface are upscaled from the rigorous description of its unit cell using the two scale asymptotic homogenisation. The procedure relies on the existence of the boundary layer confined in the vicinity of the resonators operating in the deep subwavelength regime. The model is capable of describing sound interaction with the array of resonators positioned above or upon the substrate, so that the out of plane direction becomes an additional degree of freedom in the design. It is shown that at the leading order, the behaviour of the resonant surface is described in terms of the effective admittance, whose unconventional properties makes it possible to achieve the total sound absorption at multiple frequencies, broadband absorption, the phase reversal of the reflected wave at resonance and the control of the enclosure modes. The theory is validated by experiments performed in the impedance tube and in the anechoic environment using a surface array of spherical Helmholtz resonators with the extended inner neck. Experimental results confirm the effectiveness and robustness of the resonant surface for control of sound waves.

Subwoofer array modeling and optimization

In the last few years, configuring subwoofer arrays in order to achieve a desired sound radiation pattern has become one of the most discussed topics in the sound reinforcement industry. The directivity of such arrays of low-frequency loudspeakers can typically be controlled by means of delay, gain, and polarity settings applied to the individual elements. A new software solution is presented that allows modeling and optimizing such setups, including various cardioid configurations as well as end-fire and steered setups. Frequencies down to 20 Hz can be investigated. It is also explained how coherent sound superposition at low frequencies and incoherent interaction of sound waves at high frequencies can be simulated consistently by means of a cross-over frequency band. Finally, an optimization method is presented that allows computing elemental delays automatically based on a user-defined coverage angle for the array.

Auditory illusions arising from lack of visual clues

Auditory illusions arising from lack of visual clues will be discussed and related to prehistoric cave art and Stonehenge. In the ancient past, when the wave characteristics of sound were not understood, virtual sound effects arising from complex sound wave interactions (echoes, reverberations, interference patterns, etc.) were misinterpreted as invisible beings (echo spirits, thunder gods, sound absorbing bodies, etc.) as described in ancient myths around the world. Scientifically conducted experiments involving blindfolded participants show how various ambiguous sounds can be interpreted in more than one way—like optical illusions. The blindfold in this case is a metaphor for ignorance of the wave nature of sound. It is proposed that ancient peoples were looking at the apparent source of sound and not seeing anything, and so concluded that the sounds emanated from beings that could not be seen. These experiments thus can help in understanding our ancestors’ perceptions and reactions to sounds they considered mysterious and spooky. These discoveries are just a few examples of research findings that are springing from the new field of Archaeoacoustics. See https://sites.google.com/site/rockartacoustics/ for further examples.

Auditory illusion demonstrations as related to prehistoric cave art and Stonehenge

Auditory illusions will be demonstrated, and their relevance to prehistoric cave art and Stonehenge revealed. In the ancient past, when the wave characteristics of sound were not understood, virtual sound effects arising from complex sound wave interactions (echoes, reverberations, interference patterns, etc.) were misinterpreted as invisible beings (echo spirits, thunder gods, sound absorbing bodies, etc.) as described in ancient myths around the world. In this session, live hands-on demonstrations will be given to small groups of students who can experience for themselves these types of auditory illusions. Participants will get to experience various sounds and will be given the task of interpreting what the sounds are, first blindfolded, then with visual cues. (Previous student reactions have included “Whoa!,” “Wow!,” “Amazing!,” “Cool!,” and “What??.”) These scientifically conducted experiments show how various ambiguous sounds can be interpreted in more than one way—like optical illusions—and thus can help in understanding our ancestors’ reactions to sounds they considered mysterious and spooky. These discoveries are just a few examples of research findings that are springing from the new field of Archaeoacoustics. See https://sites.google.com/site/rockartacoustics/ for further examples.

“Good acoustics” is culturally determined: Evidence that prehistoric performance space selection was based on different world views

“Ideal” performance spaces are in the ear of the listener. Cases will be presented to argue that the response to a particular set of acoustic characteristics of a space is a function of the world view of the audience/performers. For example, in today's modern society that values speech intelligibility and appreciation of polyphonic classical and contemporary music, a distinct echo in a performance space is considered an unforgivable fault. However, in the ancient past when wave characteristics of sound were not understood, virtual sound effects arising from complex sound wave interactions (echoes, reverberations, interference patterns, etc.) were misinterpreted as invisible beings (echo spirits, thunder gods, sound absorbing bodies, etc.) as described in ancient myths around the world. Some of these myths contain accounts of purposeful searches for the best echoes, which were worshiped. Scientifically conducted experiments involving blindfolded participants show how various ambiguous sounds can be interpreted in more than one way (like optical illusions). Sound level measurements demonstrate that cave paintings and canyon petroglyphs were placed in locations with the strongest echoes. Prehistoric flutes have been found in reverberating caves. These experiments thus can help in understanding our ancestors’ perceptions and reactions to sounds they considered supernatural (https://sites.google.com/site/rockartacoustics/).

Pressure-induced vortex rings multiplication as a source of vorticity in superfluids

A modified version of the Gross-Pitaevskii equation (GPE) combined with the Newton equation is used to model the interaction of sound waves with heavy particles, propagating in a quantum fluid. In contrast with the classical cubic GPE we use the equation with the 7-th order nonlinearity, in which the correct equation of state for the fluid is incorporated. Such modification makes this formalism applicable to study pressure variation effects. In the considered process, the particle, moving with an initial velocity, creates a vortex ring excitation in the fluid. A subsequent change of pressure, which appears because of the interaction of the particle with a sound wave, initiates the vortex multiplication process. As a result of the following vortex interplay, the moving particle becomes surrounded by a decaying turbulent cloud with high degree of vorticity. It is demonstrated how at certain stage of evolution of the cloud, the kinetic energy of the fluid circulation around the particle increases in a resonant manner. In accordance with the hydrodynamic Bernoulli principle, an increase of the speed of the fluid (kinetic energy) results in a decrease of pressure (potential energy) around the particle. Such mechanism may help to understand the details of experiments with exploding electron bubbles in liquid helium, as a result of the interaction with sound waves.

Modeling light-sound interaction in nanoscale cavities and waveguides

AbstractThe interaction of light and sound waves at the micro and nanoscale has attracted considerable interest in recent years. The main reason is that this interaction is responsible for a wide variety of intriguing physical phenomena, ranging from the laser-induced cooling of a micromechanical resonator down to its ground state to the management of the speed of guided light pulses by exciting sound waves. A common feature of all these phenomena is the feasibility to tightly confine photons and phonons of similar wavelengths in a very small volume. Amongst the different structures that enable such confinement, optomechanical or phoxonic crystals, which are periodic structures displaying forbidden frequency band gaps for light and sound waves, have revealed themselves as the most appropriate candidates to host nanoscale structures where the light-sound interaction can be boosted. In this review, we describe the theoretical tools that allow the modeling of the interaction between photons and acoustic phonons in nanoscale structures, namely cavities and waveguides, with special emphasis in phoxonic crystal structures. First, we start by summarizing the different optomechanical or phoxonic crystal structures proposed so far and discuss their main advantages and limitations. Then, we describe the different mechanisms that make light interact with sound, and show how to treat them from a theoretical point of view. We then illustrate the different photon-phonon interaction processes with numerical simulations in realistic phoxonic cavities and waveguides. Finally, we introduce some possible applications which can take enormous benefit from the enhanced interaction between light and sound at the nanoscale.

Interaction of a plane progressive sound wave with anisotropic cylindrical shells

An exact analysis based on the wave function expansion is carried out to study the scattering of a plane harmonic acoustic wave incident at an arbitrary angle upon an arbitrarily thick helically filament-wound (anisotropic) cylindrical shell submerged in and filled with compressible ideal fluids. Using the laminated approximation method, a modal state equation with variable coefficients is set up in terms of appropriate displacement and stress functions and their cylindrical harmonics to present an analytical solution based on the three-dimensional exact equations of anisotropic elasticity. Taylor’s expansion theorem is then employed to obtain the solution to the modal state equation, ultimately leading to calculation of a transfer matrix. Following the classic acoustic resonance scattering theory (RST), the scattered field and response to surface waves are determined by constructing the partial waves and obtaining the background (non-resonance) and resonance components from it. The solution is particularly used for the isolation and identification of excited resonances of an air-filled and water submerged Graphite/Epoxy cylindrical shell as the circumnavigating helically propagating waves. In addition, the sensitivity of resonances associated with various modes of wave propagation appearing in the backscattered amplitude to the perturbation in the material’s elastic constants is examined. Furthermore, non-axisymmetric dynamic behavior of the anisotropic shell is illustrated by analyzing the directivity pattern associated to the angular distribution of the far-field form function amplitude. The effects of winding angle of filaments and the shell wall-thickness on the frequency response of the shell are also investigated. For verification, the wave propagation characteristics of the anisotropic shell (which have been extracted from the main body of the solution) and the far-field form function amplitude of a limiting case are considered and fair agreement with the solutions available in the literature are established.

Perception and coding of high-frequency spectral notches: potential implications for sound localization.

The interaction of sound waves with the human pinna introduces high-frequency notches (5–10 kHz) in the stimulus spectrum that are thought to be useful for vertical sound localization. A common view is that these notches are encoded as rate profiles in the auditory nerve (AN). Here, we review previously published psychoacoustical evidence in humans and computer-model simulations of inner hair cell responses to noises with and without high-frequency spectral notches that dispute this view. We also present new recordings from guinea pig AN and “ideal observer” analyses of these recordings that suggest that discrimination between noises with and without high-frequency spectral notches is probably based on the information carried in the temporal pattern of AN discharges. The exact nature of the neural code involved remains nevertheless uncertain: computer model simulations suggest that high-frequency spectral notches are encoded in spike timing patterns that may be operant in the 4–7 kHz frequency regime, while “ideal observer” analysis of experimental neural responses suggest that an effective cue for high-frequency spectral discrimination may be based on sampling rates of spike arrivals of AN fibers using non-overlapping time binwidths of between 4 and 9 ms. Neural responses show that sensitivity to high-frequency notches is greatest for fibers with low and medium spontaneous rates than for fibers with high spontaneous rates. Based on this evidence, we conjecture that inter-subject variability at high-frequency spectral notch detection and, consequently, at vertical sound localization may partly reflect individual differences in the available number of functional medium- and low-spontaneous-rate fibers.

Theory and experiment of the resonance sound wave interactions in water

Equations governing nonlinear interactions among acoustic waves in water which satisfy the resonance conditions are derived from the Burgers equation. Taking into account of the second-order nonlinear, the three-wave interaction is the fundamental process of the interaction equations. Then, taking the three-wave interaction equation as an example, the energy transfer mechanism among the three acoustic waves is quantitatively analyzed. And the three-wave sound energy propagation is studied through numerical calculation. An interesting phenomenon is found that, when the three acoustic waves meet the relationship of a weak low-frequency sound and two strong high-frequency sounds, the energy of low-frequency sound will be amplified or reduced in some regions during the three-wave propagation. And the location and size of the regions are affected by the acoustic wave amplitude, frequency, and phase. The variation severities of low-frequency acoustic wave energy are mainly determined by other two high-frequency acoustic wave energy. The frequencies of two high-frequency sound waves have little effects on the energy of low-frequency sound wave. The region whether is amplification or reduction is determined by the phase difference of three waves. The variation laws of low-frequency sound energy are also verified by the experimental results in river.

Ultrasonic Properties of Plutonium Monochalcogenides

A computer program in MATLAB is developed for the numerical computation of ultrasonic properties in Pu- monochalcogenides in present investigation in the temperature range 100-300K along , and 111> directions. The program calculates the second and third order elastic constants, relaxation time, ultrasonic coupling constants and ultrasonic attenuation by considering the interaction of sound wave with complete spectrum of thermal phonon modes and by taking two basic parameters i.e., nearest neighbour distance and hardness parameters. The program has been successful for the study of (i) temperature dependence of the second and third order elastic constants, (ii) temperature and crystallographic dependence of ultrasonic velocities for longitudinal and shear waves with thermal relaxation time, ultrasonic coupling constants and ultrasonic attenuation for PuS, PuSe and PuTe. The behaviour of acoustic parameters as a function of higher temperature has been discussed in correlation with other thermophysical parameters.

Climatical Characterization of Northern Arabian Sea for OFDM Based Underwater Acoustic Communication

The effects of climatic changes on the Underwater Acoustic (UWA) communication are addressed here with the aim to evaluate the performance of proposed scheme in the whole year specifically for the north Arabian Sea. Oceanic channel is a most challenging medium for the design of underwater wireless communication as it offers various unwanted degradations in terms of frequency-dependent attenuation, multipath spread, long path delays, etc. Multipath spread having extended delay spread further deteriorates the communication packet (s) and in result, mutilation of entire signal, i.e., Inter-Symbolic Interference (ISI) is occurred. Detailed analysis for the interaction of sound wave with the water mass is essential for the design of Underwater Acoustic (UWA) communication. In particular, at varying temperature and warm surface site like Ormara, Pakistan (north-western region of Arabian Sea), where a very strong seasonal dependency may be observed due to climatic changes. OFDM, being the most feasible communication scheme and well suited for underwater environment is utilized in this study for the effect's monitoring. In this study, we are presenting the effects of climate on the selected region of North-west Arabian Sea and validating our work on Zero Padded (ZP) OFDM scheme for UWA communication. Relevant meteorological and oceanic data are obtained from open source buoy ARGOS ID 2901374 and Global ARGOS marine atlas (Worldwide tracking and environmental monitoring by satellite). For each of March, June, September and December we find a temperature and salinity with respect to the depth and subsequently calculate the sound speed in the specific channel. Bellhop ray tracing program is used to obtain the receiving path's amplitudes and delays for respective channel modeling and ZP OFDM based communication system. Simulation results explain the effects of climate in the transmission and endorse that ZP-OFDM is a viable choice for high-rate communications in these types of oceanic channel. In this way system level design of the underwater acoustic wireless communication/telemetry can be optimized for the most prevailing channel conditions.

On the interaction of shock waves and sound waves in transonic buffet flow

To support Lee's buffet mechanism model [B. H. K. Lee, “Self-sustained shock oscillations on airfoils at transonic speeds,” Prog. Aerosp. Sci. 37, 147–196 (2001)10.1016/S0376-0421(01)00003-3], the sound wave propagation in the flow field outside the separation of a transonic buffet flow at a Mach number M∞ = 0.73 and an angle of attack α = 3.5° over a DRA 2303 supercritical airfoil is determined using high-speed particle-image velocimetry. Furthermore, the shock wave is influenced by an artificial sound source which evidently changes the shock oscillation properties. The dominant buffet mechanism is shown to be a feedback loop between the shock position and the noise generation at the trailing edge of the airfoil. The sound wave propagation speed is detected by correlating the surface pressure signals and the velocity fluctuations in the flow field. The quantitative results for the natural and the artificial sound source convincingly coincide and are in good agreement with a reformulated version of Lee's buffet model.