Acoustic Field Data Research Articles

Inference of geoacoustic model parameters from acoustic field data: Perspectives on Geoacoustic Inversion

Estimation of parameters of geoacoustic models from acoustic field data has been a central research theme in acoustical oceanography and ocean acoustics. During the past several decades, highly efficient numerical inversion techniques have been developed that provide model parameter estimates and their uncertainties based on statistical inference methods. However, the methods are model-based and the inversions are prone to errors related to model mismatch. In any event, the inversions can generate only effective models of the true structure of the ocean bottom, which is generally highly variable over relatively small spatial scales in range and depth. There are also questions about the theory for modelling sound propagation in porous sediment media that raise doubt about the validity of inversion results. In most inversions, a visco-elastic theory is used, but is this the most appropriate propagation model? Another question is about the impact of neglecting shear waves in geoacoustic models. Most inversions assume a fluid model of the ocean bottom. This paper revisits issues that have raised questions about limitations of geoacoustic inversion methods, and discusses the impact of various mitigation measures that have been applied. The paper concludes with musings about new inversion techniques based on machine learning.

A Multi-Objective Geoacoustic Inversion of Modal-Dispersion and Waveform Envelope Data Based on Wasserstein Metric

The inversion of acoustic field data to estimate geoacoustic parameters has been a prominent research focus in the field of underwater acoustics for several decades. Modal-dispersion curves have been used to inverse seabed sound speed and density profiles, but such techniques do not account for attenuation inversion. In this study, a new approach where modal-dispersion and waveform envelope data are simultaneously inversed under a multi-objective framework is proposed. The inversion is performed using the Multi-Objective Bayesian Optimization (MOBO) method. The posterior probability densities (PPD) of the estimation results are obtained by resampling from the exploited state space using the Gibbs Sampler. In this study, the implemented MOBO approach is compared with individual inversions both from modal-dispersion curves and the waveform data. In addition, the effective use of the Wasserstein metric from optimal transport theory is explored. Then the MOBO performance is tested against two different cost functions based on the L2 norm and the Wasserstein metric, respectively. Numerical experiments are employed to evaluate the effect of different cost functions on inversion performance. It is found that the MOBO approach may have more profound advantages when applied to Wasserstein metrics. Results obtained from our study reveal that the MOBO approach exhibits reduced uncertainty in the inverse results when compared to individual inversion methods, such as modal-dispersion inversion or waveform inversion. However, it is important to note that this enhanced uncertainty reduction comes at the cost of sacrificing accuracy in certain parameters other than the sediment sound speed and attenuation.

Drone Detection and Localization Using Enhanced Fiber-Optic Acoustic Sensor and Distributed Acoustic Sensing Technology

In recent years, the widespread use of drones has led to serious concerns about safety and privacy. Drone detection using microphone arrays has proven to be a promising method. However, it is challenging for microphones to serve large-scale applications due to the issues of synchronization, complexity, and data management. Moreover, distributed acoustic sensing (DAS) using optical fibers has demonstrated its advantages in monitoring vibrations over long distances but does not have the necessary sensitivity for weak airborne acoustics. In this work, we present, to the best of our knowledge, the first fiber-optic quasi-distributed acoustic sensing demonstration for drone surveillance. We develop enhanced fiber-optic acoustic sensors (FOASs) for DAS to detect drone sound. The FOAS shows an ultra-high measured sensitivity of −101.21 re. 1rad/μPa, as well as the capability for high-fidelity speech recovery. A single DAS can interrogate a series of FOASs over a long distance via optical fiber, enabling intrinsic synchronization and centralized signal processing. We demonstrate the field test of drone detection and localization by concatenating four FOASs as a sensing array and capturing the airborne sound remotely through DAS. Both the waveforms and spectral features of the drone sound are recognized. With acoustic field mapping and data fusion, accurate drone localization is achieved with a root-mean-square error (RMSE) of 1.47 degrees. This approach holds great potential in large-scale sound detection applications, such as drone detection or city event monitoring.

On acoustic fields of complex scatters based on physics-informed neural networks

This paper proposes a modeling method for scattered acoustic fields under complex structures based on Physics-informed Neural Networks (PINNs), with particular attention to the acquisition of training sets and the embedding of physical governing equations. First, using acoustic simulation softwares to obtain the scattered acoustic field under various models, and select the scattered acoustic field data at several moments as the training sets. Then, according to the characteristics of the simulated model, the corresponding physical equations have been embedded in the loss function of the network. We tested the method by predicting the propagation of ultrasonic waves and the scattering of acoustic fields with various simple scatterers. Furthermore, we also use PINN to simulate the scattered acoustic field of the real complex damaged structure. The results show that the mean square error (MSE) between prediction and ground truth is in the order of 10-4, which illustrate PINN can effectively simulate the propagation and reflection of ultrasonic waves, and can also simulate the scattered acoustic field of complex structures accurately. The meshless and accurate characteristics of PINN provide a reliable alternative for the theoretical prediction of complex and continuous scattered acoustic fields.

Vector acoustic properties of the underwater sound field from multiple, simultaneously observed ships

Vector acoustic properties of the underwater sound field simultaneously observed from multiple surface vessels during the recently completed (May–June 2022) experiment on the New England Mud Patch (NEMP) approximately 100 km south of Cape Cod are discussed. The properties, such as bearing, degree of polarization, and other non-dimensional parameters are derived from a 4 by 4 field matrix composed of pressure and 3-component velocity, and a 3 × 3 matrix composed of only velocity components. The measurements were made with two sensing systems, separated by 21 km, referred to as an Intensity Vector Autonomous Recorder (IVAR), and identified as IVAR-1 and IVAR-2. Individual ship CPAs tracks are identified with automated ship identification (AIS) data. In this presentation, the two sources of measured vector acoustic field data combined with the AIS data are exploited to study the effect of interaction of multiple acoustic sources on a received vector field.

Calibration and Verification of Operation Parameters for an Array of Vectrino Profilers Configured for Turbulent Flow Field Measurement around Bridge Piers—Part I

Flow mapping around bridge piers is crucial in estimating scour development potential under different flow conditions. The reliable measurement of turbulence and the estimation of Reynolds stress can be achieved on scaled models under controlled laboratory experiments using high-frequency Acoustic Doppler Velocimeter Profilers (ADVP) for flow measurement. The aim of this paper was to obtain operation parameters for an array of Vectrino Profilers for turbulent flow field measurement to reliably measure the flow field around bridge piers. Laboratory experiments were conducted on a scaled river model set up in an open channel hydraulic flume. Flow field data were measured on three characteristic profiles, each containing five measurement points collected by ADVPs configured as an array of two instruments. The determination of the operation parameters was done as a two-step process—calibration through the flume’s pump flow rate and verification with Acoustic Doppler Current Profiler RioGrande field data. Based on the results, the following setup for ADVPs’ operation parameters can be used to obtain reliable flow data in the scour hole next to the bridge pier: adaptive Ping Algorithm, Transmit Pulse Size of 4 mm and Cell Size of 1 mm.

Localization of Immersed Sources by Modified Convolutional Neural Network: Application to a Deep-Sea Experiment.

A modified convolutional neural network (CNN) is proposed to enhance the reliability of source ranging based on acoustic field data received by a vertical array. Compared to the traditional method, the output layer is modified by outputting Gauss regression sequences, expressed using a Gaussian probability distribution form centered on the actual distance. The processed results of deep-sea experimental data confirmed that the ranging performance of the CNN with a Gauss regression output was better than that using single regression and classification outputs. The mean relative error between the predicted distance and the actual value was ~2.77%, and the positioning accuracy with 10% and 5% error was 99.56% and 90.14%, respectively.

Detection on a distributed network using information geometry.

A passive detection scheme based on information geometry is tested on underwater acoustic field data acquired through multiple sensors from the Distributed Network Consensus experiment. These detectors use a signal discovery method wherein a target is detected when the statistics of that signal are sufficiently different from those in a broadband background. The signal excess is viewed here as the non-Euclidean distance between two probability distributions interpreted as points in a Riemannian manifold. The SNR is artificially lowered to create a low SNR scenario and it is shown that in spite of this, the geometric detectors perform quite well.

Straightforward impedance eduction method for non-grazing incidence wave with multiple modes

The control of modern aeroengine noise poses great challenge to the design of acoustic liners, due to the existence of multiple higher-order modes over a very wide frequency range in acoustic nacelles. In order to meet the pressing demand, the straightforward impedance eduction method is further developed such that it can be applied to more general acoustic environment where there are both plane mode and higher-order modes incident upon a test liner. A novelty of the present method is using a diagonally mounted microphone array on the opposite wall of the test liner in a flow duct, thus the measured wall sound pressure simultaneously contains the information of the modes in both the axial and transverse directions. Then, the employment of Prony's method enables the realization of the full modal decomposition to the acoustic field in the flow duct. Numerical experiments simulating acoustic fields with a finite element model are conducted to investigate and validate the feasibility of the present method for both a small-scale and a large-scale flow ducts. Two ceramic tubular liners and a perforated liner are tested as specimens, whose impedance values to be educed are known a priori by means of existing impedance models. Random perturbation is added into the acoustic field data to simulate realistic noisy acoustic environments. The results show that the present method can educe the imposed impedance with a good accuracy when the liner specimens are subjected to the sound field composing of multiple incident modes including several transverse modes in both ducts. The frequency scope of the impedance eduction is considerably extended when compared with the methods restricted by the assumption of plane incident mode, with the upper frequency reaching up to 6.0 kHz and 5.0 kHz for the ducts, respectively. A parametric study indicates that the accuracy of impedance eduction can be promoted by increasing the signal-to-noise ratio and the number of microphones.

Review of acoustic comfort evaluation in dwellings—part I: Associations of acoustic field data to subjective responses from building surveys

Acoustic comfort is a concept hardly described in the literature. But it has been used in engineering typically to refer to low noise or annoyance in order to invoke no discomfort. Current standardized methods for airborne and impact sound reduction are deployed to assess acoustic comfort in dwellings. However, the measured sound pressure levels do not represent comfort. The latter should include further the human perception of the acoustic environment. Therefore, this article reviews studies that approached acoustic comfort through the association of objective and subjective field data, combining in situ acoustic measurements and survey responses from residents. We evaluated the studies using Bradford Hill’s criteria. Most researches focus on self-reported noise annoyance while some others on satisfaction responses. Many studies were found incomprehensibly described: often vital data of statistical evaluation or study design are lacking. The results indicate that noise is a significant issue in living environments, especially certain impact noise types. The use of extended low-frequency spectra down to 50 Hz was suggested for impact measurements in order to predict better self-reported noise response. Greater problems with low-frequency transmission are displayed in lightweight structures which perform inefficiently compared to heavyweight components. Harmonization of presented results and study design details should be taken into account for future articles.

An experimental benchmark for geoacoustic inversion methods

Over the past 25 years, many methods have been developed for estimating parameters of geoacoustic models of the ocean bottom from acoustic field data. The methods involved model-based comparisons between experimental data and calculated fields or field quantities. Benchmarking workshops based on simulated field data confirmed the ability of the methods for inverting geoacoustic model parameters for range-independent and range-dependent ocean environments. Although there are many published examples of geoacoustic inversions in various different ocean environments, the methods have not been tested in an experimental benchmark. This paper describes the design of an experimental benchmark for geoacoustic inversion methods, and presents an analysis of the performance of the methods with experimental data. The benchmark involves application of different inversion methods to data spanning a frequency band from 50to 2500 Hz that were obtained at a single well-surveyed ocean bottom site. The performance metric involves comparisons of: estimated geoacoustic profiles against the ground truth information of the site; modal wavenumbers for the inverted models; and transmission loss calculations based on the estimated models against measured data. The analysis shows that the methods are capable of estimating realistic geoacoustic profiles, with sound speed the most reliable estimated model parameter.

A preliminary look at the acquisition of acoustic field data using selected smartphone apps

Numerous smartphone applications exist that measure sound levels in the acoustic field. In some cases, these apps also provide additional acoustic data in the form of real-time spectral analysis. Yet, very few studies exist that have evaluated the validity of these apps for sound level measurement. Notably, these studies evaluated performance in the laboratory and only assessed the accuracy of the measurement of sound levels. Here, we present field-acquired data on the accuracy of dB level measurement and spectral analysis of a variety of smartphone apps for both Android and iOS platforms. We then discuss the feasibility of using these applications for field data acquisition.

Karakteristik Gelombang Stoneley dalam Menentukan Permeabilitas Reservoir Sumur Pemboran

In-situ permeability is an important factor in determining whether an economical drilling oil wells to be mined. Therefore, the calculation in determining the true value of permeability with an attempt to take a further decision, whether the industry is continued or not. Research through study literature is obtained a mathematical modeling from Matheu and Toksoz's work which contains the components of acoustic wavesattenuation factor and rock permeability factor. Furthermore, by combining some of the concepts and theories, mathematical models are used for acoustic field data logs and other data which are required to get permeability. Data from the acoustic log is analyzed to determine the time delay for P, S and Stoneley waves, then determination of the speed, frequency and attenuation factor, especially for wave Stoneley. In this permeability calculations, it is assumed that the condition of the rock formations in the area of measurement is a permeable rock and contains fractures. The results show that the permeability in measurement area at a depth position indicates suitable with the data of rock state.

Interpretation of Acoustic Field Data for Leak Detection in Ductile Iron and Copper Water-Distribution Pipes

AbstractThe acoustic emission (AE) method is becoming popular for detecting leaks in municipal water mains where leaks are identified and the locations are determined through the interpretation of ...

A critical review of geoacoustic inversion: What does it really tell us about the ocean bottom?

Estimation of parameters of geoacoustic models from acoustic field data has been a central theme in acoustical oceanography over the past three decades. Highly efficient numerical techniques based on Bayesian inference have been developed that provide estimates of geoacoustic model parameters and their uncertainties. However, the methods are model-based, requiring accurate knowledge of the acoustic propagation conditions in the ocean to carry out the inversion. More recent research has revealed fundamental limitations of model-based inversion methods in conditions of unknown temporal and spatial variations in the water. In addition, the inversions can generate only effective models of the true structure of the ocean bottom, which are generally highly variable over relatively small spatial scales. There are other questions about the theory for sound propagation in porous sediment media that raise doubt about the validity of inversion results. In most inversions, a visco-elastic theory is used, but is this correct? This paper reviews successes and failures of geoacoustic inversion to understand the limitation of model-based methods. Research directions are suggested in conclusion that show promise for development of new approaches. [Work supported by ONR.]

Cement bond quality evaluation based on acoustic variable density logging

Abstract A new method of cement bond quality evaluation was proposed by combining numerical simulation and calibrated cased hole acoustic logging data. The effects of the cement channel angle and the quality of the second bond interface (the interface of cement with formation) on acoustic variable density logging data were analyzed. Based on the analysis result, a new cement bond evaluation standard was presented after revising the traditional CBL/VDL method. The axisymmetric acoustic field was simulated by real axis integral method, while the non-axisymmetric acoustic field was simulated by 2.5-D finite differential method. After comparing with the calibrated cased hole acoustic logging data, the research has the below results: the numerical simulation result matches with the calibrated well logging data very well and the new method is reliable; the amplitude of the first acoustic arrival in the case hole decreases as the angle of cement channel decreases, and the denser the cement is, the faster the amplitude of cased hole acoustic waveform decays; the lower limit of cement channel angle is around 45 degrees which can be detected by acoustic logging; the formation acoustic waveform is not easy to be detected in time domain, however it is easy to be detected in frequency domain, especially in limestone formation, the first arrival only can be detected when the annulus width of the second bond interface is small. According to the research result of the numerical simulation of cased hole acoustic field and acoustic variable density logging data, new evaluation criteria of cement bound quality were presented.

A coupled FEM-BEM algorithm for the inverse acoustic medium problem

We present a numerical scheme for reconstructing the refractive index of an inhomogeneous two dimensional medium using acoustic far field data. The numerical scheme is based only on the mild assumption that the inhomogeneous medium is contained in the unit disk, and does not require axis-symmetry or other similar restrictions. Reconstruction of the refractive index, without the assumption of axis-symmetry, is achieved using an expansion in the high order Logan--Shepp polynomials. The Logan--Shepp expansion coefficients of the refractive index are formulated as the solution of a nonlinear equation, which is solved using a regularised Newton-type solver. Nonlinear function evaluations, which involve solving a forward scattering problem, are performed using an efficient coupled finite-element/\penalty \exhyphenpenalty boundary element method, which ensures that the radiation condition is incorporated exactly. The scheme is demonstrated by reconstructing challenging continuous and discontinous media from noisy far field data. References M. Abramowitz and I. A. Stegun, editors. Handbook of Mathematical Functions . National Bureau of Standards, 1964. doi:10.1119/1.1972842 . K. Atkinson, D. Chien, and O. Hansen. A spectral method for elliptic equations: the Dirichlet problem. Adv. Comput. Math. , 33:69–1891, 2014. doi:10.1007/s10444-009-9125-8 . A. Barnett and L. Greengard. A new integral representation for quasi-periodic fields and its application to two-dimensional band structure calculations. J. Comput. Phys. , 229:6898–6914, 2010. doi:10.1016/j.jcp.2010.05.029 . D. Colton and R. Kress. Inverse Acoustic and Electromagnetic Scattering Theory . Springer, 2012. doi:10.1007/978-1-4614-4942-3 . S. Gutman and M. Klibanov. Regularized quasi-Newton method for inverse scattering problems. Math. Comput. Modelling , 18:5–31, 1993. doi:10.1016/0895-7177(93)90076-B . S. Gutman and M. Klibanov. Iterative method for multi-dimensional inverse scattering problems at fixed frequencies. Inverse Problems , 10:573–599, 1994. doi:10.1088/0266-5611/10/3/006 . S. Gutman and M. Klibanov. Two versions of quasi-Newton method for multidimensional inverse scattering problem. J. Comput. Acoust. , 1:197–228, 1993. doi:10.1142/S0218396X93000123 . M. Hanke. A regularizing Levenburg-Marquardt scheme, with applications to inverse groundwater filtration problems. Inverse Problems , 13:79–95, 1997. doi:10.1088/0266-5611/13/1/007 . T. Hohage. On the numerical solution of a three-dimensional inverse medium scattering problem. Inverse Problems , 17:1743–1763, 2001. doi:10.1088/0266-5611/17/6/314 . T. Hohage. Fast numerical solution of the electromagnetic medium scattering problem and applications to the inverse problem. J. Comput Phys. , 214:224–238, 2006. doi:10.1016/j.jcp.2005.09.025 . A. Kirsch. An Introduction to the Mathematical Theory of Inverse Problems . Springer, 2011. doi:10.1007/978-1-4419-8474-6 . A. Kirsch and P. Monk. An analysis of the coupling of finite-element and Nystrom methods in acoustic scattering. IMA J. Numer. Anal , 14:523–544, 1994. doi:10.1093/imanum/14.4.523 . B. F. Logan and L. A. Shepp. Optimal reconstruction of a function from its projections. Duke Math. J. , 42:645–659, 1975. doi:10.1215/S0012-7094-75-04256-8 .

Using broadband acoustic signals and modal behavior to assess scales of ocean variability in shallow water waveguides

The sound speed fields of the continental shelf water column are anisotropic and have “fronts” related to propagating internal wave packets. The angle between a broadband acoustic signal’s source–receiver propagation track and the propagating “fronts” affects its modal composition. If the temporal variability of the modal behavior of the acoustic signals are monitored in time and space, one might identify the fluid process that causes the changes to the sound speed field. In this paper, we first present a heuristic view of how the modal properties of broadband signals can be affected by the sound speed field variability caused by propagating internal wave packets. We then present three days of acoustic field data acquired on vertical and horizontal arrays placed in ~100 m of water about 20 km from the location of acoustic signal sources. Temporal changes in the received acoustic signal's modal composition will be compared to numerical simulations. The changes in modal composition will be correlated to internal wave induced variability in the horizontal refraction of the signals.

Visualization and measurement of the acoustic field of the piston transducer

PurposeThis paper aims to characterize the acoustic field radiated by the piston transducer and measure a few parameters through the data visualization method.Design/methodology/approachUsing the theoretical model of the ultrasonic transducer, the acoustic field data were acquired by scanning the ultrasound field of the piston transducer. And the visualized graphs of the ultrasonic data were displayed through 3D graphs including slice, iso‐surface and volume rendering, respectively. Furthermore, a few parameters of the transducer including beam width and spread angle were measured using the visualized data.FindingsThe visualized graphs of the acoustic field radiated by the piston transducer show that the data visualization method can expose obviously the space distribution of the ultrasound field and describe directly the cylindrical shape. And this method provides the basis of reliable measurement and assess for the ultrasonic transducer.Research limitations/implicationsThis paper presents a kind of measured method of the acoustic parameters using the visualized data. The measurement range has limitation.Practical implicationsThis method is possible used in Medical ultrasonic.Originality/valueThis paper presents the visualized description of the acoustic field of the piston transducer and a measurement of two acoustic parameters using the visualized data.

The inverse problem of acoustic wave scattering by an air-saturated poroelastic cylinder

The efficient use of plastic foams in a diverse range of structural applications like in noise reduction, cushioning, and sleeping mattresses requires detailed characterization of their permeability and deformation (load-bearing) behavior. The elastic moduli and airflow resistance properties of foams are often measured using two separate techniques, one employing mechanical vibration methods and the other, flow rates of fluids based on fluid mechanics technology, respectively. A multi-parameter inverse acoustic scattering problem to recover airflow resistivity (AR) and mechanical properties of an air-saturated foam cylinder is solved. A wave-fluid saturated poroelastic structure interaction model based on the modified Biot theory and plane-wave decomposition using orthogonal cylindrical functions is employed to solve the inverse problem. The solutions to the inverse problem are obtained by constructing the objective functional given by the total square of the difference between predictions from the model and scattered acoustic field data acquired in an anechoic chamber. The value of the recovered AR is in good agreement with that of a slab sample cut from the cylinder and characterized using a method employing low frequency transmitted and reflected acoustic waves in a long waveguide developed by Fellah et al. [Rev. Sci. Instrum. 78(11), 114902 (2007)].