# Kyle S. Spratt's research while affiliated with University of Texas at Austin and other places

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## Publications (27)

Shear waves are employed in medical ultrasound imaging because they reveal variations in viscoelastic properties of soft tissue. Frequencies below 1 kHz are required due to the substantially higher attenuation and lower propagation speeds than for compressional waves. Shear waves exhibiting particle motion in the direction of propagation, referred...

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ABSTRACT
Shear waves are employed in medical imaging to reveal variations in the viscoelastic properties of soft tissues, which are useful biomarkers for pathologies such as breast lesions and liver disease. Shear wave excitation methods that employ acoustic radiation force or surface vibration with a small piston have limitations...

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ABSTRACT
Shear wave propagation is employed in medical ultrasound imaging, because it reveals variation in the viscoelastic properties of tissue. Frequencies below 1 kHz are required for imaging with shear waves in soft tissue due to their high attenuation and low propagation speeds, compared to compressional waves with frequencies...

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ABSTRACT
A spring reverb is an electromechanical device used to artificially reverberate an audio signal, i.e. to impart a sense of spaciousness to the audio signal, as if the sound were being emitted into a reverberant acoustic space. The device consists of a number of helical springs set into motion by electrically driven magneti...

A simplified model is presented describing acoustic scattering from a toroidal gas bubble in a compressible liquid. It is assumed that the volume oscillations of the bubble are small enough that a linear approximation is appropriate, and furthermore, that the bubble is large enough that the dominant loss mechanism is radiation damping. An expressio...

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ABSTRACT
An angular spectrum approach can be used to obtain high-resolution measurements of the acoustic plane wave reflection and transmission coefficients corresponding to a given planar sample of material. Such an approach involves exciting the sample with a compact broadband source located in the near field and then scanning th...

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ABSTRACT
An acoustic Leaky Wave Antenna (LWA) is an electronically simple device that enables frequency-dependent directional sound radiation or reception by coupling a single acoustic transducer to an analogue dispersive waveguide. While most acoustic LWA have focused on airborne acoustic waves, the successful demonstration of aco...

Ultrasonic measurements were performed on a thin steel plate submerged in water in order to obtain the plane-wave transmission coefficient as a function of angle and frequency. An angular spectrum approach was utilized wherein the acoustic field parallel to the plate was scanned with sufficient spatial accuracy to obtain a frequency-wavenumber desc...

Low-power acoustic imaging instrumentation can have a significant impact on underwater exploration and monitoring by enabling longer duration missions. Acoustic leaky wave antennas (LWAs), which consist of a dispersive analogue aperture coupled to a single electro-mechanical transducer, are a promising technological solution to address the demandin...

If you listen carefully to the sound that sparkling wine makes after it is poured, you ll hear the size distribution of the ringing bubbles.

One complication of characterizing the response of acoustic metamaterials is that models often assume the medium is of infinite extent. On the other hand, material property measurement can only be done with samples of finite size. The result is that acoustic field measurements include the effects of edge diffraction and scattering from fixtures. Th...

The McKinney Fellowship in Acoustics is a graduate research fellowship awarded to one student per year by Applied Research Laboratories at The University of Texas at Austin (ARL:UT). Created in 2006 and named after former lab director Chester M. McKinney, the fellowship is meant to foster quality research in acoustics while maintaining the strong c...

Sparkling wine, such as the variety coming from the Champagne region of France, is a beverage that is at least partially famous for its carbon dioxide bubbles, a byproduct of the secondary fermentation process that occurs after bottling. A well-known theory, though hardly accepted universally, posits that the quality of a sparkling wine can be asce...

The work by Strasberg on small volume oscillations of bubbles with arbitrary shape [J. Acoust. Soc. Am. 25, 536–537 (1953)] is here extended to include the effects of radiation damping. An expression for the far-field scattering amplitude from an arbitrarily shaped bubble is given in terms of a quantity that is mathematically equivalent to the elec...

The low shear moduli of soft elastic media permit the generation of shear waves with large acoustic Mach numbers that can exhibit waveform distortion and even shock formation over short distances. Waves that converge onto a cylindrical focus experience significant dispersion, causing waveforms at the focus and in the post-focal region to differ sig...

The recent work by Ainslie and Leighton [J. Acoust. Soc. Am. 126, 2163 (2009)] pointed out that there exist two different expressions in the literature for the scattering cross-section of a spherical gas bubble in liquid. The difference between the two expressions is contained in the term corresponding to the losses due to acoustic radiation. The m...

The characterization of a performance space provides an excellent opportunity to provide students with first-hand experience with many fundamental aspects of room acoustics including reverberation, linear time-invariant systems, measurement methods, and post-processing of real-world data to estimate room metrics. This talk reports recent measuremen...

Large encapsulated bubbles have recently been used for abating low-frequency anthropogenic underwater noise [J. Acoust. Soc. Am. 135, 1700-1708 (2014)]. The use of encapsulation allows for the possibility of bubbles that are significantly nonspherical in their equilibrium state. Strasberg [J. Acoust. Soc. Am. 25, 536-537 (1953)] investigated the re...

Alleyways bounded by flat, reflective, parallel walls and smooth concrete floors can produce impulse responses that are surprisingly rich in texture, featuring a long-lasting modulated tone and a changing timbre, much like the sound of a didgeridoo. This work explores alleyway acoustics with acoustic measurements and presents a computational model...

This work studies the forced dynamical behavior of a heterogeneous material containing metamaterial inclusions undergoing large deformations. The inclusions exhibit non-monotonic stress-strain behavior, modeled with an expansion to third order in volume strain, where the coefficients of the expansion depend on the metamaterial structure. The result...

Alleyways bounded by flat, reflective, parallel walls and smooth concrete floors can produce impulse responses that are surprisingly rich in texture, featuring a long-lasting modulated tone and a changing timbre, much like the sound of a didgeridoo. This work explores alleyway acoustics with acoustic measurements and presents a computational model...

Large encapsulated bubbles have recently been described for use in abating low-frequency anthropogenic underwater noise [J. Acoust. Soc. Am. 130, 3325-3332 (2011)], and the use of encapsulation allows for the possibility of bubbles that are nonspherical in their equilibrium state. For the purpose of more accurately determining such bubbles' resonan...

The method of analyzing an acoustic space by way of modal decomposition is well established. In this work, a computational structure employing modal decomposition is introduced for synthesizing artificial reverberation, implementing the modes using a collection of resonant filters, each driven by the source signal and summed in a parallel structure...

A coupled pair of nonlinear parabolic equations was derived by Zabolotskaya [1] that model the transverse components of the particle motion in a collimated shear wave
beam propagating in an isotropic elastic solid. Like the KZK equation, the parabolic equation for shear wave
beams accounts consistently for the leading order effects of diffraction,...

In the past decade there has been a surge in the optics literature regarding the unique characteristics of focused, radially-polarized light beams. Of particular interest is the existence of a longitudinal component to the electric field in the focal region of the beam, of comparable amplitude to the radial component and yet with a smaller beamwidt...

This work is motivated by the transient elastography experiments described by Catheline etal. [J. Am. Stat. Assoc. 105, 2941-2950 (1999)], the purpose of which was to measure the phase speed of shear waves propagating through tissue phantoms. In that work, a small circular piston was used to generate the shear waves, the motion of which was perpend...

This presentation describes an extension of the work by Wochner et al. [J. Acoust. Soc. Am. 123, 2488?2495 (2008)], wherein a coupled pair of nonlinear parabolic equations was derived for the two components of the particle motion perpendicular to the axis of a shear wave beam in an isotropic hyperelastic medium. Although the equations derived in th...

## Citations

... However, when the holes are not spherical (which is often the case in practical applications), the analytical solution is a priori not available. Luckily, like for air bubbles in liquids, 18,19 the acoustics of a cavity in an elastomer is mainly governed by its volume 1 , provided that the cavity is not too elongated. Hence, if one considers a cylindrical cavity with radius R and height H, all the previous equations can be applied by considering the sphere of equivalent radius: ...

... Kang modelled the acoustics of a town square using image-source and radiosity methods to predict the sound pressure level [25]. Collecchia et al. studied the acoustic characteristics of narrow alleyways and simulated their interesting behavior using the image-source method [26]. ...

... From a physics point of view, the forces acting on bubbles in an acoustic field (acoustic radiation forces or Bjerknes forces) are of great importance and remain an active research area (Spratt et al., 2015). The BEM framework as described in Section 4.3 would be very suited to simulate such forces. ...

Reference: Blake, bubbles and boundary element methods

... Historically, this concept has informed acoustic analysis of both interiors [2] and musical instruments [3], and has informed digital audio synthesis techniques including the Functional Transformation Method [4], MODALYS [5], MOSAIC [6], and advanced numerical modeling of strings [7][8][9] and bridges [10]. Recently, modal analysis of rooms has informed a new family of artificial reverberation algorithms called "modal reverb," where a room's modal response is synthesized directly as a sum of parallel filters [11,12]. Modifications to the basic modal reverb algorithm have been used to produce novel abstract audio effects based on distortion, pitch, and time-scale modification [13] as well as an abstract Hammondorgan-based reverberation algorithm [14]. ...

Reference: Modal Audio Effects: A Carillon Case Study

... Strasberg [3,4] expanded the expression to the more general cases of an ideal gas bubble of arbitrary shape using an empirical shape factor method. Spratts et al. [5] attempted to formalize the shape factor using concepts from electromagnetic wave propagation theory (Stratton [6]). However, for multiple bubbles, it becomes complicated to obtain mathematical expressions for the resonance responses of the system. ...

... With respect to stress-strain relationships, β 2 invokes quadratic nonlinearities, and β 3 , cubic nonlinearities. These constants were introduced in papers by Zabolotskaya and collaborators [14,21,22]. With this connection, it is a simple matter to identify our formulation (2.17) of the equations of motion with that of Wochner et al. [14]. ...