Sound Propagation Research Articles

A simplified and controllable model of mode coupling for addressing nonlinear phenomena in sound synthesis processes

This paper introduces a simplified and controllable model for mode coupling in the context of modal synthesis. The model employs efficient coupled filters for sound synthesis purposes, intended to emulate the generation of sounds radiated by sources under strongly nonlinear conditions. Such filters generate tonal components in an interdependent way and are intended to emulate realistic perceptually salient effects in musical instruments in an efficient manner. The control of energy transfer between the filters is realized through a coupling matrix. The generation of prototypical sounds corresponding to nonlinear sources with the filter bank is presented. In particular, examples are proposed to generate sounds corresponding to impacts on thin structures and to the perturbation of the vibration of objects when it collides with an other object. The sound examples presented in the paper and available for listening on the accompanying site illustrate that a simple control of the input parameters allows the generation of sounds whose evocation is coherent and that the addition of random processes yields a significant improvement to the realism of the generated sounds.

Nonlocal active sound control for composite regions

In the active sound control problem, additional sound sources, known as control sources, are implemented at the perimeter of a protected domain. The control sources can generate secondary sound inside the shielded domain, which attenuates incoming noise. This leads to an inverse source problem. Such a problem becomes much more complicated if some desired sound is generated inside the protected area. The algorithm, known as nonlocal active sound control, successfully tackles this problem due to the projection property of the nonlocal operators involved. With the application of nonlocal control, noise generated outside the shielded domain is attenuated while the internal component of sound remains unaffected. In the present paper, the approach of nonlocal active sound control is significantly modified to be applicable to composite domains. In the test cases, three different sound propagation patterns are realized such as sound shielded from peers, free propagation, and selective sound cancelation. Numerical simulation is carried out in both frequency and time domains for broadband regimes. The results show that, even with a relatively small number of sensors and control sources, significant noise attenuation can still be achieved for a predetermined communication pattern among individual subdomains.

Experimental Investigation Of The Flow-Acoustic Interaction In Human Phonation

In the human phonation process, acoustic standing waves in the vocal tract can influence the fluid flow through the glottis. To investigate the amount of two-way coupling between the flow field and the acoustics, the supraglottal flow field has been recorded via high-speed particle image velocimetry (PIV) in a synthetic larynx model for several configurations with different vocal tract lengths. Based on the obtained velocity fields, aeroacoustic source terms were computed. Furthermore, the hydrodynamic pressure in the vocal tract was recorded via wall pressure measurements. The recordings revealed that near a vocal tract resonance frequency, the focal fold oscillation frequency jumps onto the resonance. This is accompanied by a substantial relative increase in aeroacoustic sound generation efficiency. At the same time, the glottal volume flow needed for stable vocal fold oscillation decreases strongly. The pressure measurements showed that acoustic anti-resonances of the vocal tract directly dampen the harmonic content of the hydrodynamic pressure field when matching frequencies. This result shows that back-coupling of the acoustics onto the flow field does not only occur in the case where the vocal fold oscillation frequency and a resonance frequency of the vocal tract match, but also under more other conditions.

FireSonic: Design and Implementation of an Ultrasound Sensing-Based Fire Type Identification System.

Accurate and prompt determination of fire types is essential for effective firefighting and reducing damage. However, traditional methods such as smoke detection, visual analysis, and wireless signals are not able to identify fire types. This paper introduces FireSonic, an acoustic sensing system that leverages commercial speakers and microphones to actively probe the fire using acoustic signals, effectively identifying fire types. By incorporating beamforming technology, FireSonic first enhances signal clarity and reliability, thus mitigating signal attenuation and distortion. To establish a reliable correlation between fire type and sound propagation, FireSonic quantifies the heat release rate (HRR) of flames by analyzing the relationship between fire-heated areas and sound wave propagation delays. Furthermore, the system extracts spatiotemporal features related to fire from channel measurements. The experimental results demonstrate that FireSonic attains an average fire type classification accuracy of 95.5% and a detection latency of less than 400 ms, satisfying the requirements for real-time monitoring. This system significantly enhances the formulation of targeted firefighting strategies, boosting fire response effectiveness and public safety.

Frequency-focused sound data generator for fault diagnosis in industrial robots

Abstract A frequency-focused sound data generator was developed for the in situ fault sound diagnosis of industrial robot reducers. The sound data generator, based on a conditional generative adversarial network, selects a target frequency range without relying on domain knowledge. A sound dataset of normal and faulty harmonic drive rotations of in situ industrial robots was collected using an attachable wireless sound sensor. The generated sound data were evaluated based on the fault diagnosis accuracy of a simple classifier trained using the generated data and tested using real data. The proposed method well-defined the frequency feature clusters and produced high-quality data, exhibiting up to 16.0% higher precision score on normal and 13.0% higher accuracy on weak-fault harmonic drive compared with the conventional methods, achieving fault diagnosis accuracy of 95.6% even in situations of fault data comprising only 5% of the normal data.

Influence of inhomogeneous temperature and field distribution on sound generation and its effect on reflectivity of a thin film heated by a femtosecond pulse

One of the main methods for obtaining information about the generation of sound pulses in metals is to measure the reflection coefficient of a probe wave. Various theoretical models are used to interpret the results of measuring the contribution to reflection coefficient ΔR(t) due to sound-generated displacements of lattice atoms. The purpose of this paper is to establish the degree of accuracy of models used in the case of sound generation in thin films exposed to a femtosecond pulse. It is shown below that the assumption of uniform heating used for thin films is justified if the film thickness is less than the film heating depth and for thicker films at times greater than the film heating time over the entire thickness. For optically thick films, a relatively simple expression for the field can be used. If the film thickness is less than the skin layer depth of the pump field, then it is necessary to consider the field reflection from a substrate. In this case, depending on the optical properties of the metal and the substrate, taking into account reflection can lead to either an increase or a decrease in ΔR(t). It has been established that if the skin layer at the frequency of probe radiation is less than the film heating depth, then taking into account temperature gradients in the equation for the displacement of lattice atoms leads to small changes in ΔR(t). This makes it possible to significantly simplify calculations of the displacement of lattice atoms.

Acoustic Propagation in the Near‐Surface Martian Atmosphere

AbstractThis work introduces a comprehensive model of sound propagation on Mars, in light of the recent operation of several microphones on the Martian surface. The main outcome of this work is an operational acoustic model capable of simulating the sound field created by any source, at any location on the Martian surface, at any time. Expanding on the result of previous work (Gillier et al., 2024, https://doi.org/10.1029/2023je008257), we use the parabolic equation method for sound propagation in order to obtain the overall sound field produced by a source, in a given atmospheric composition and state, and accounting for ground properties. The resulting model enables the study of acoustics on Mars, and has the potential also to be used to probe the properties of the Martian environment using acoustic measurements with known sources. We investigate the effects of the Martian ground and the vertical profile of temperature and wind, on sound propagation. We find that the ground has a minor effect on sound propagation, and the wind profile strongly influences sound propagation as on Earth. However, the midday near surface temperature profiles on Mars are shown to cause refraction, which generates non‐negligible acoustic losses that are an order of magnitude stronger than typical refraction‐related acoustic losses on Earth. We show that the effect of the Martian atmospheric turbulence is to slightly reduce the acoustic losses due to refraction. Finally, we apply our model to show that refraction and atmospheric turbulence have a negligible effect on the propagation of sound from Ingenuity to the Perseverance rover.

Interference of the direct and ground-reflected waves in the atmosphere with volumetric scatteringa).

The interference of the direct and ground-reflected sound waves is significantly affected by volumetric scattering in the atmosphere, such as scattering by turbulence and forest. In the present article, the existing theory describing this interference is generalized to three somewhat independent but equally important cases. First, the attenuation of the direct and ground-reflected waves caused by backscattering is addressed. Second, the existing theory is extended for statistically quasi-homogeneous turbulence in which the variances and length scales of the temperature and wind velocity fluctuations depend on the height above the ground. Third, the existing theory, which was previously formulated only for near-horizontal sound propagation, is generalized to slanted sound propagation as pertinent to elevated sound sources. Numerical results for slanted propagation demonstrate that atmospheric turbulence can significantly increase the sound pressure level at the interference minima. The extended theory of the interference of the direct and ground-reflected waves in the atmosphere with volumetric scattering is important for practical applications, such as auralization of flying aircraft and sound propagation in a forest, and can be adapted to radio wave propagation.

Development of aircraft noise simulation framework J-FRAIN based on component-wise sound source models

In order tomake detailed and accurate predictions of aircraft noise around airports, we have developed “J-FRAIN”, a new aircraft noise simulation framework that can precisely predict the time histories of noises emitted from each major aircraft noise source during the landing approach phase at ground observation points. This article describes the elements of the developed framework—data acquisition, sound source modeling, propagation modeling, and ground noise prediction—and present some application examples. To develop the framework, we first deployed a 30m-diameter microphone array under the final approach path to an international airport to measure acoustic maps of several civil aircraft types in flight. The sound powers of major aircraft noise-emitting components were then estimated quantitatively by domain integration of the deconvolved acoustic maps at five emission angles in the plane of the glideslope, and the directivities of each noise source were determined. Next, component-wise sound source regression models for engines and airframe noise sources were created based on the physical relationships between engine rotation speed, airspeed, and the deployment angle of high-lift devices, and the coefficients in each model were determined to minimize the root-mean-square error between the measured and predicted sound power levels. The phenomena of atmospheric absorption and ground effect during the propagation of radiated sounds were also incorporated into the framework. Actual flight parameter values were used as inputs to the completed framework, and it was confirmed that the predicted time histories of sound pressure levels on the ground agreed with measured data to within 2 dB if ground effect was properly considered. Finally, as sample applications that use the unique features of the proposed J-FRAIN framework, the article discusses the evaluation of the contributions of each aircraft noise source at noise observation points under the final approach path to the airport and the impact assessment of flight operations on noise.

Low-frequency non-reciprocal sound propagation features in thermoacoustic waveguide.

Thermoacoustic waveguides are systems of hollow tubes and thermally graded porous segments that can operate as active materials where acoustic waves receive energy from an external heat source. This work demonstrates that by adjusting the pore geometry several unique low-frequency propagation features arise from the complex-valued band structure of periodic thermoacoustic waveguides that reflect into the acoustic pressure field within finite-length systems. Numerical methods have been employed to model waveguides with porous segments constituted by cylindrical inclusions (parallel pins). In periodic structures, a critical frequency emerges where the sign of the refractive index in one direction of propagation changes, thus zero- and negative-unidirectional refractive index, unidirectional energy transport, and amplification/attenuation crossover effects may take place. On the other hand, the study of the acoustic pressure field shows that, for wave packets with either direction of propagation, finite-length waveguides may behave as active acoustic metamaterials with zero- or negative-refractive index. The acoustic pressure field in the waveguide, generated by an upstream source, may exhibit increasing amplitude and phase recovery farther away from the source, mimicking the field created by a downstream source, propagating upstream in a non-active medium.

Information geometry analysis example for absolute and relative transmission loss in a shallow ocean

The model manifold, an information geometry tool, is a geometric representation of a model that can quantify the expected information content of modeling parameters. For a normal-mode sound propagation model in a shallow ocean environment, transmission loss (TL) is calculated for a vertical line array and model manifolds are constructed for both absolute and relative TL. For the example presented in this paper, relative TL yields more compact model manifolds with seabed environments that are less statistically distinguishable than manifolds of absolute TL. This example illustrates how model manifolds can be used to improve experimental design for inverse problems.

The Impact of the Spatial Variability of the Seafloor on Midfrequency Sound Propagation During the Target and Reverberation Experiment 2013

The Impact of the Spatial Variability of the Seafloor on Midfrequency Sound Propagation During the Target and Reverberation Experiment 2013

A Narrative Analysis of J. G. Roederer’s The Physics and Psychophysics of Music

This paper conducts narrative analysis for the rhetorical critique of Roederer's <i>The Physics and Psychophysics of Music</i>, a prominent textbook of music science. It is possible to analyze implicit narratives even for texts in non-narrative genres. In science textbooks, implicit narratives can be analyzed in structural, educational, and research contexts. Roederer's satisfies structural coherence by composing a book in a way that deals with the perception of pitch, volume, timbre, and harmony according to the stages of sound generation, transmission, and acceptance in a structural context. In an educational context, a book is composed of content that students may be interested in for a scientific understanding of music to satisfy material coherence, and the validity of narrative fidelity is satisfied through the pursuit of reliable knowledge through experience data and improved observational equipment according to the method of constructing scientific knowledge. From the research context, we can confirmed that characterological coherence is secured by satisfying the truthfulness of narrative fidelity through the update of knowledge throughout the four editions, and by revealing that the knowledge of music science is being built through the activities of major researchers.

Effect of Amplitude and Frequency on the Speed of Sound Waves in Air and Water Using PhET Simulation

Sound waves can occur not only in solid medium but also in air and water mediums. The effect of amplitude and frequency on the speed of sound waves differs between air and water mediums. The speed of sound waves cannot be seen with the naked eye. A virtual lab is needed to determine the speed of sound wave propagation. The purpose of this study is to determine the effect of amplitude and frequency on the speed of sound waves in air and water medium. The research method used is a quantitative method by conducting experiments online using the PhET application. PhET is used because it can carry out interactive simulations to facilitate research that cannot be done in real terms, but must make use of an effective virtual lab. The results obtained, namely in the medium of air and water, it is proven that the amplitude and frequency are directly proportional to the speed of sound wave propagation. In conclusion, sound waves travel faster in the water medium than in the air medium. Sound waves travel faster in the water medium because in liquid the particles are closer together than in the air medium, so sound waves will travel faster.

Correction to: Sound propagation simulation in the Strait of Hormuz using ROMS and RAMGEO models

Correction to: Sound propagation simulation in the Strait of Hormuz using ROMS and RAMGEO models

Direct simulations of external flow and noise radiation using the generalized interpolation-supplemented cascaded lattice Boltzmann method

Direct simulations of external flow and the associated noise radiation are studied by an improved lattice Boltzmann method, i.e., the generalized interpolation-supplemented cascaded lattice Boltzmann method (GICLBM). In this method, the cascaded collision scheme is used to improve the numerical stability of the conventional collision schemes, and the generalized interpolation approach is used in the particle streaming process so as to allow a non-uniform and body-fitted mesh partition. With that, both near- and far-field flow dynamics and noise radiation are resolved simultaneously. In order to capture sound waves, the perfectly matched layer is also implemented so as to avoid waves reflecting to and polluting the inner acoustic field. Moreover, a novel index technique is developed for the GICLBM to enable implicit streaming, which brings an efficient memory reduction. Three cases are then performed to showcase the feasibility, accuracy, extensibility, and efficiency of the present framework, including flow past a square cylinder, flow past an elliptic cylinder, and flow past a NACA 0012 airfoil, each implemented with a type of body-fitted mesh. Both the fluid dynamic and noise radiation are found to be in good agreement with results using the Navier–Stokes solvers. This study demonstrates the potential of the GICLBM for accurately and efficiently simulating external problems as well as sound generation and propagation.

Acoustic black hole with functionally graded perforated rings

A new class of acoustic black hole (ABH) waveguides is presented, which relies in its operation on an array of optimally designed functionally graded perforated rings (FGPRs). In this manner, the developed ABH is provided with built-in energy dissipation characteristics generated by virtue of the flow through perforations, which enhances its acoustic absorption behavior and makes the speed of the propagating waves vanish faster when reaching the end of the waveguide. Furthermore, the particular design of the rings enables sandwiching of additional porous absorbing layers between the rings to further boost the absorption characteristics of the proposed ABH. Accordingly, the operating principle of the new class of ABH is radically different from that of the conventional ABH that employs sequential solid-flat rings of decreasing inner radii to create a virtual power law taper necessary for generating the black hole effect, but through reactive means rather than the effective dissipative means of the proposed ABH. Therefore, this paper develops a transfer matrix modeling (TMM) approach to model the absorption and reflection characteristics of the new class of ABH, in an attempt to predict its behavior, optimize the selection of its design parameters, and more importantly, demonstrate its merits as effective means for controlling sound propagation. Numerical examples are presented to highlight the merits and behavior of the proposed ABH. Predictions of the TMM are validated against experimental results that are available in the literature for one and two micro-perforated plates. Comparisons are also established between the ABH with FGPR and the conventional ABH in order to distinguish the behavior and underlying principles of their operations.

Sound propagation in the presence of non-isothermal sheared flow refraction and metasurface impedance reflection

Sheared flow can profoundly influence the aeroacoustic performance of near-wall structures like metasurfaces on moving vehicles. In this work, a refractive generalized Snell’s law is developed by combining Snell’s law with the generalized Snell’s law to manipulate anomalous reflections in an idealized sheared flow, comprising a uniform flow region and a stationary air region with velocity and temperature gradients. Theoretical analysis and numerical simulations of planar wave reflection by metasurface impedance under non-isothermal sheared flows are conducted, yielding favorable predictions of the zone of silence, as well as anomalous and total reflection behaviors. The total reflection between the shear layer and the metasurface is analyzed with the objective of confining incident wave below the shear layer. Remarkably, a specific configuration of hot-sheared flow and metasurface length can achieve total absorption over a range of incident wave angles from 0° to almost 90°. Moreover, the refractive generalized Snell’s law, extended to account for directional deflection induced by flow convection, is utilized to regulate sound beam reflection, resulting in satisfactory outcomes under sheared conditions. This study offers a theoretical framework for wave control under non-isothermal and sheared flow conditions, which cannot be resolved by the traditional generalized Snell’s law, and can be implemented in the design of metasurfaces for moving applications.

Experimental study of sound wave propagation patterns

The present study compares the behavior of different sound types and their sources concerning distance. Experimental findings demonstrate a consistent reduction in noise levels with increasing distance from the sound origin, aligning with anticipated sound propagation patterns. Median noise level reductions are quantified, showing decreases from 72.7 dB at the source to 54.8 dB at a distance of 3 m. Pulsed sounds exhibit pronounced fluctuations and peaks at close distances, while steady and blended sounds maintain more uniform levels. An exponential model accurately characterizes the noise reduction phenomenon (R² = 0.8664), underscoring its applicability for construction noise control. These results offer valuable insights into sound propagation dynamics and provide a basis for developing effective noise control strategies.

Optimization of vibration and sound insulation in GPLRC honeycomb structures based on circle chaos mapping and Levy flight-enhanced YDSE with constraints

Utilizing the first-order shear deformation theory (FSDT) and Hamilton's principle, dynamic equations for tunable Poisson's ratio metamaterial honeycomb sandwich panels have been derived. These panels include petal-shaped, star-shaped, and butterfly-shaped designs. The acoustic response of these panels when subjected to plane harmonic sound waves has been formulated, treating them as fluid-structure interaction systems. To enhance the structural vibration and sound propagation attributes, traditional metallic aluminum has been replaced with graphene platelet-reinforced composites (GPLRC). Through computational analysis and finite element simulation data, the natural frequencies and sound transmission loss (STL) characteristics of the panels have been determined. An improved heuristic algorithm called the circle chaos mapping and levy flight enhanced Young's double-slit experiment optimizer (CLYDSE) has been introduced to optimize their vibrational and acoustic properties. This algorithm builds upon Young's double-slit experiment optimizer (YDSE) by incorporating circle chaos mapping for initializing a monochromatic light source and utilizing the levy flight principle for more accurate search results. These enhancements allow the CLYDSE algorithm to avoid local optima and improve convergence velocity. A penalty function method was employed to establish mass and equivalent elastic modulus as optimization constraints, aiming to achieve superior specific stiffness. Finally, structural optimization using the proposed CLYDSE method was conducted to enhance the vibrational and acoustic performance of the three types of honeycomb sandwich panels. The results validate the effectiveness of the theoretical model in predicting vibration and acoustic response, as well as the improved performance of the CLYDSE algorithm in terms of convergence velocity and optimization accuracy. This demonstrates the algorithm's efficacy in refining the acoustic and vibrational qualities of these advanced honeycomb structures.