scholarly journals Estimation of Tissue Attenuation from Ultrasonic B-Mode Images—Spectral-Log-Difference and Method-of-Moments Algorithms Compared

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2548
Author(s):  
Dinah Maria Brandner ◽  
Xiran Cai ◽  
Josquin Foiret ◽  
Katherine W. Ferrara ◽  
Bernhard G. Zagar
Keyword(s):  
Mass Density ◽  
Sound Field ◽  
Nonlinear Wave Propagation ◽  
Ultrasound Simulation ◽  
Simulation Tools ◽  
Spatially Resolved ◽  
Single Voxel ◽  
Medical Diagnostic ◽  
Scattering Strength ◽  
The Time Domain

We report on results from the comparison of two algorithms designed to estimate the attenuation coefficient from ultrasonic B-mode scans obtained from a numerical phantom simulating an ultrasound breast scan. It is well documented that this parameter significantly diverges between normal tissue and malignant lesions. To improve the diagnostic accuracy it is of great importance to devise and test algorithms that facilitate the accurate, low variance and spatially resolved estimation of the tissue’s attenuation properties. A numerical phantom is realized using k-Wave, which is an open source Matlab toolbox for the time-domain simulation of acoustic wave fields that facilitates both linear and nonlinear wave propagation in homogeneous and heterogeneous tissue, as compared to strictly linear ultrasound simulation tools like Field II. k-Wave allows to simulate arbitrary distributions, resolved down to single voxel sizes, of parameters including the speed of sound, mass density, scattering strength and to include power law acoustic absorption necessary for simulation tasks in medical diagnostic ultrasound. We analyze the properties and the attainable accuracy of both the spectral-log-difference technique, and a statistical moments based approach and compare the results to known reference values from the sound field simulation.

High Amplitude Sound Propagation at Low Frequencies in a Flow Duct Lined With Resonators: A Time Domain Solution

1988 ◽  
Vol 110 (4) ◽  
pp. 545-551 ◽  
Author(s):  
A. Cummings ◽  
I.-J. Chang
Keyword(s):  
Time Domain ◽  
Internal Combustion Engines ◽  
Sound Propagation ◽  
Sound Field ◽  
High Amplitude ◽  
Combustion Engines ◽  
Low Frequencies ◽  
The Time Domain ◽  
Flow Duct ◽  
Good Agreement

A quasi one-dimensional analysis of sound transmission in a flow duct lined with an array of nonlinear resonators is described. The solution to the equations describing the sound field and the hydrodynamic flow in the neighborhood of the resonator orifices is performed numerically in the time domain, with the object of properly accounting for the nonlinear interaction between the acoustic field and the resonators. Experimental data are compared to numerical computations in the time domain and generally very good agreement is noted. The method described here may readily be extended for use in the design of exhaust mufflers for internal combustion engines.

Acoustic Design of a Local Scatterer in a Phase-Space

1995 ◽  
Author(s):  
John J. McCoy ◽  
Ben Zion Steinberg
Keyword(s):  
Mechanical Property ◽  
Phase Space ◽  
Mass Density ◽  
Sound Field ◽  
Design Strategy ◽  
Local Region ◽  
Small Scale ◽  
Far Field ◽  
Acoustic Design ◽  
Surrounding Fluid

Abstract A spatially local region of mechanical property heterogeneity is a source of scattering, by which a structure-borne mechanical wavefield is released as sound, to a surrounding fluid. We consider the case of a scatterer which is of the order of the size of the wavelength of a plate-wave field for a frequency which is below coincidence. A design strategy for reducing the strength of the scattered sound field in the fluid, at far-field distances from the scatterer, by adding a small-scale structure to the heterogenity, is presented. The design is accomplished in a wavelet-based phase-space. Emphasized is a significant distinction required of the added structure, depending on the heterogeneity applying to a measure of the local mass density or the local bending stiffness.

Sound Field Prediction and Separation in a Moving Medium Using the Time-Domain Equivalent Source Method

2017 ◽  
Vol 103 (3) ◽  
pp. 401-410 ◽  
Author(s):  
Zhao-Huan Wang ◽  
Chuan-Xing Bi ◽  
Xiao-Zheng Zhang ◽  
Yong-Bin Zhang
Keyword(s):  
Time Domain ◽  
Sound Field ◽  
Moving Medium ◽  
Equivalent Source ◽  
Source Method ◽  
The Time Domain ◽  
Equivalent Source Method

A High-Resolution Continuous-Scan Acoustic Measurement Method for Turbofan Engine Applications

2015 ◽  
Vol 137 (12) ◽  
Author(s):  
Parthiv N. Shah ◽  
Håvard Vold ◽  
Dan Hensley ◽  
Edmane Envia ◽  
David Stephens
Keyword(s):  
Spatial Resolution ◽  
Sound Field ◽  
Rotational Frequency ◽  
Scale Model ◽  
Acquisition Time ◽  
Time Signal ◽  
Noise Sources ◽  
Turbofan Engine ◽  
Complex Envelope ◽  
The Time Domain

Detailed mapping of the sound field produced by a modern turbofan engine, with its multitude of overlapping noise sources, often requires a large number of microphones to properly resolve the directivity patterns of the constituent tonal and broadband components. This is especially true at high frequencies where the acoustic wavelength is short, or when shielding, scattering, and reflection of the sound field may be present due to installation effects. This paper presents a novel method for measuring the harmonic and broadband content of complex noncompact noise sources using continuously moving (referred to here as continuous-scan (CS)) microphones in conjunction with a state-of-the-art phase-referencing technique. Because the microphones are moving through the sound field produced by the noise sources, they effectively provide infinite spatial resolution of the sound directivity over the scan path. In this method, harmonic (i.e., shaft-coherent) content at the integer multiples of the instantaneous shaft rotational frequency is first extracted from the time signal using a tachometer signal and the Vold-Kalman (VK) filter. The residual broadband signal is then filtered in the time domain in fractional octave bands. The broadband spectra of the signals from the moving microphones are then computed at arbitrary positions along their scan paths using weighted averages (based on Chebyshev polynomial zero-crossings) and the assumption of a complex envelope that varies slowly over a spatial scale whose lower bound is set by the acoustic wavenumber. A benefit of this method is that the decomposition of the total measured sound field into a stochastic superposition of components preserves a meaningful phase definition for each “partial field” associated with a given shaft order (SO). This preservation of phase data enables the forward or backward projection of each of these partial fields using acoustical holography (AH). The benefits of the CS method are demonstrated using acoustic data acquired for a 22-in. scale-model fan stage run at the NASA Glenn Research Center's 9-foot by 15-foot wind tunnel. Two key outcomes of the work include (1) significant improvement in the spatial resolution of the measured sound field and (2) reduction in the overall data acquisition time. Additionally, the methods described here lead to new opportunities for noise source diagnostics and visualization.

scholarly journals Aeroacoustic analysis using natural Helmholtz–Hodge decomposition

2018 ◽  
Vol 7 (1) ◽  
pp. 113-122 ◽  
Author(s):  
Daniel Haufe ◽  
Johannes Gürtler ◽  
Anita Schulz ◽  
Friedrich Bake ◽  
Lars Enghardt ◽  
...  
Keyword(s):  
Velocity Field ◽  
Temporal Frequency ◽  
Fluid Velocity ◽  
Three Dimensional ◽  
Sound Field ◽  
Region Of Interest ◽  
Hodge Decomposition ◽  
Acoustic Frequency ◽  
Oscillation Velocity ◽  
The Time Domain

Abstract. The analysis of aeroacoustic phenomena is crucial for a deeper understanding of the damping mechanisms of a sound-absorbing bias flow liner (BFL). For this purpose, simultaneous measurements of the sound field and the flow field in a BFL are required. The fluid velocity can serve as the measurand, where both the acoustic particle velocity and the aerodynamic flow velocity contribute and, thus, can be acquired simultaneously. However, there is a need to separate these two quantities to distinguish between them. This is challenging because they generally coincide with each other in the time domain. Due to the interaction of sound and flow in a BFL, both velocities also overlap in the temporal frequency domain, having a coherent oscillation at the acoustic frequency. For this reason, the recently developed natural Helmholtz–Hodge decomposition (NHHD) is applied to separate both quantities from the measured oscillation velocity field in the spatial domain. The evaluation of synthetic vector field data shows that the quality of the decomposition is enhanced when a smaller grid size is chosen. The velocity field in a generic BFL, necessarily recorded within a three-dimensional region of interest at more than 4000 measurement locations, is evaluated using NHHD. As a result, the measured oscillation velocity in the BFL is dominated by the flow that is related to vortices and also by irrotational aerodynamic flow. Moreover, indications for an aeroacoustic source near the facing sheet of the liner are revealed.

High Fidelity Methods for Modeling Nonlinear Wave Propagation in One-Dimensional Waveguides

2012 ◽  
Author(s):  
Yu Liu ◽  
Pooya Ghaderi ◽  
Andrew J. Dick
Keyword(s):  
Wave Propagation ◽  
Perturbation Method ◽  
Frequency Component ◽  
Constitutive Law ◽  
Nonlinear Wave Propagation ◽  
Nonlinear Force ◽  
Spectral Finite Element Method ◽  
The Time Domain ◽  
Spectral Finite Element ◽  
Dynamic Shape

In this paper, two new methods are proposed to study wave propagation in materials with constitutive law that have nonlinear terms. In the first method, the gauge transformation is used to derive the dynamic shape function. A perturbation method is then applied in order to derive an equation for the wavenumber. The influence of the nonlinearity takes the form of a dependence of the wavenumber on the magnitude of the corresponding frequency component. Under the small amplitude and weak nonlinearity assumptions of the perturbation method, the wavenumber is incorporated into the spectral finite element method (SFEM). The second approach is a numerical method based on alternating frequency-time (AFT) iterations. The nonlinear term represented as a residual nonlinear force term is reduced through the alternating iterations between the time-domain and the frequency-domain. Finally, response behaviors under impact loading predicted with these methods are studied and compared to equivalent linear response behavior.

scholarly journals Time Domain Spherical Harmonic Processing with Open Spherical Microphones Recording

2021 ◽  
Vol 11 (3) ◽  
pp. 1074
Author(s):  
Huiyuan Sun ◽  
Thushara D. Abhayapala ◽  
Prasanga N. Samarasinghe
Keyword(s):  
Time Domain ◽  
Spherical Harmonic ◽  
Microphone Array ◽  
Sound Field ◽  
Microphone Arrays ◽  
Spatial Audio ◽  
Harmonic Decomposition ◽  
Spherical Harmonic Decomposition ◽  
The Time Domain ◽  
Spherical Microphone Arrays

Spherical harmonic analysis has been a widely used approach for spatial audio processing in recent years. Among all applications that benefit from spatial processing, spatial Active Noise Control (ANC) remains unique with its requirement for open spherical microphone arrays to record the residual sound field throughout the continuous region. Ideally, a low delay spherical harmonic recording algorithm for open spherical microphone arrays is desired for real-time spatial ANC systems. Currently, frequency domain algorithms for spherical harmonic decomposition of microphone array recordings are applied in a spatial ANC system. However, a Short Time Fourier Transform is required, which introduces undesirable system delay for ANC systems. In this paper, we develop a time domain spherical harmonic decomposition algorithm for the application of spatial audio recording mainly with benefit to ANC with an open spherical microphone array. Microphone signals are processed by a series of pre-designed finite impulse response (FIR) filters to obtain a set of time domain spherical harmonic coefficients. The time domain coefficients contain the continuous spatial information of the residual sound field. We corroborate the time domain algorithm with a numerical simulation of a fourth order system, and show the proposed method to have lower delay than existing approaches.

scholarly journals Spatial Resolution of Late Reverberation in Virtual Acoustic Environments

2021 ◽  
Vol 25 ◽  
pp. 233121652110549
Author(s):  
Christoph Kirsch ◽  
Josef Poppitz ◽  
Torben Wendt ◽  
Steven van de Par ◽  
Stephan D. Ewert
Keyword(s):  
Spatial Resolution ◽  
Sound Field ◽  
Spatial Arrangement ◽  
Room Acoustics ◽  
Hearing Research ◽  
Spatially Resolved ◽  
Minimum Number ◽  
Vector Base ◽  
Hearing Device ◽  
Acoustic Environments

Late reverberation involves the superposition of many sound reflections, approaching the properties of a diffuse sound field. Since the spatially resolved perception of individual late reflections is impossible, simplifications can potentially be made for modelling late reverberation in room acoustics simulations with reduced spatial resolution. Such simplifications are desired for interactive, real-time virtual acoustic environments with applications in hearing research and for the evaluation of hearing supportive devices. In this context, the number and spatial arrangement of loudspeakers used for playback additionally affect spatial resolution. The current study assessed the minimum number of spatially evenly distributed virtual late reverberation sources required to perceptually approximate spatially highly resolved isotropic and anisotropic late reverberation and to technically approximate a spherically isotropic sound field. The spatial resolution of the rendering was systematically reduced by using subsets of the loudspeakers of an 86-channel spherical loudspeaker array in an anechoic chamber, onto which virtual reverberation sources were mapped using vector base amplitude panning. It was tested whether listeners can distinguish lower spatial resolutions of reproduction of late reverberation from the highest achievable spatial resolution in different simulated rooms. The rendering of early reflections remained unchanged. The coherence of the sound field across a pair of microphones at ear and behind-the-ear hearing device distance was assessed to separate the effects of number of virtual sources and loudspeaker array geometry. Results show that between 12 and 24 reverberation sources are required for the rendering of late reverberation in virtual acoustic environments.

Reconstruction of semi-free transient sound field under different reflection conditions using an extended interpolated time-domain equivalent source method

2014 ◽  
Vol 229 (5) ◽  
pp. 895-905 ◽  
Author(s):  
Siwei Pan ◽  
Weikang Jiang ◽  
Shang Xiang
Keyword(s):  
Time Domain ◽  
Free Field ◽  
Sound Field ◽  
Sound Sources ◽  
Equivalent Source ◽  
Source Method ◽  
Equivalent Sources ◽  
The Time Domain ◽  
Reflecting Surface ◽  
Equivalent Source Method

Transient acoustic field can be rebuilt directly in the time-domain via the interpolated time-domain equivalent source method (ITDESM). However, this method requires that the reconstruction should be addressed in the free-field only, which can hardly be met in the engineering noise problems. To circumvent this difficulty, an extended ITDESM procedure is developed by extending the ITDESM from the free-field to the semi-free-field. In this approach, the time-domain equivalent sources are placed not only near the actual sound sources but also around their image sources with respect to the planar reflecting surface. The solving procedure of the equivalent source strengths is improved to decrease the computing load. The reflection conditions treated here can be arbitrary, i.e. both perfectly rigid and impedance-effected. Reconstruction results of the transient sound field radiated from three monopoles under different reflection conditions demonstrate the validity and applicability of the proposed method.

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