bluuebunny/crossref_metadata_2025 huggingface dataset:
High intensity focused ultrasound-induced bubbles stimulate the release of nucleic acid cancer biomarkers
Authors: Khokhlova Tatiana , Chevillet John R. , Schade George R. , Giraldez Maria D. , Wang Yak-Nam , Hwang Joo Ha , Tewari Muneesh
Published: October 2014

Recently, several nucleic acid cancer biomarkers, e.g., microRNA and mutant DNA, have been identified and shown promise for improving cancer diagnostics. However, the abundance of these biomarker classes in the circulation is low, impeding reliable detection and adoption into clinical practice. Here, the ability of HIFU-induced bubbles to stimulate release of cancer-associated microRNAs by tissue fractionation or permeabilization was investigated in a heterotopic syngeneic rat prostate cancer model. A 1.5 MHz HIFU transducer was used to either mechanically fractionate subcutaneous tumor with boiling histotripsy (BH) (~20 kW/cm2, 10 ms pulses, and duty factor 0.01) or to permeabilize tumor tissue with inertial cavitation activity (p- = 16 MPa, 1 ms pulses, duty factor 0.001). Blood was collected immediately prior to and serially up to 24-hours after treatments. Plasma concentrations of microRNAs were measured by quantitative RT-PCR. Both exposures resulted in a rapid (within 15 min), short (≤3 h) and dramatic (over ten-fold) increase in relative plasma concentrations of tumor-associated microRNAs, Histologic examination of excised tumor confirmed complete fractionation of targeted tumor by BH and localized areas of intraparenchymal hemorrhage and tissue disruption by cavitation-based treatment. These data suggest a clinically useful application of HIFU-induced bubbles for non-invasive molecular biopsy. [Grant support: NIH 1K01EB015745, R01CA154451, R01DK085714.]
Acoustic field characterization of the Waterlase2: Acoustic characterization and high speed photomicrography of a clinical laser generated shock wave therapy device for the treatment of periodontal biofilms in orthodontics and periodontics
Authors: Perez Camilo , Wang Yak-Nam , Sivriver Alina , Boutoussov Dmitri , Netchitailo Vladimir , Matula Thomas J.
Published: October 2014

Recent applications in endodontics and periodontics use erbium solid state lasers with fiber delivery in order to effectively kill bacteria and biofilms. In this paper, the acoustic field together with the bubble dynamics of a clinical portable Er,Cr:YSGG laser-generating device (Waterlase 2) was characterized. Field mapping with a calibrated PVDF hydrophone together with high speed imaging were performed in water for two different tip geometries (flat or tapered), three different tip diameters (200, 300, or 400µm), and two different laser pulse durations (60 or 700µs) at several laser pulse energy settings (5 mJ–400 mJ) for individual pulses and at different pulse repetition frequencies (5, 20, and 100 Hz). Peak positive pressures 5–50 mm away from the tip ranged from 0.1 to 2MPa, while peak negative pressures ranged from 0.1 to 1.2 MPa. There was a strong correlation between the acoustic emissions generated by the bubble and the high speed imaging dynamics of the bubble. An initial thermoelastic response, initial bubble collapse and further rebounds where analyzed individually and compared across different test parameters. For the initial thermoelastic pulse (laser generated), pulse rise times ranged from 40 to 200 ns. Differences between flat and tapered tips will be discussed.
Tissue damage produced by cavitation: The role of viscoelasticity
Authors: Johnsen Eric , Warnez Matthew
Published: October 2014

Cavitation may cause damage at the cellular level in a variety of medical applications, e.g., therapeutic and diagnostic ultrasound. While cavitation damage to bodies in water has been studied for over a century, the dynamics of bubbles in soft tissue remain vastly unexplored. One difficulty lies in the viscoelasticity of tissue, which introduces additional physics and time scales. We developed a numerical model to investigate acoustic cavitation in soft tissue, which accounts for liquid compressibility, full thermal effects, and viscoelasticity (including nonlinear relaxation and elasticity). The bubble dynamics are represented by a Keller-Miksis formulation and a spectral collocation method is used to solve for the stresses in the surrounding medium. Our numerical studies of a gas bubble exposed to a relevant waveform indicate that under inertial conditions high pressures and velocities are generated at collapse, though they are lower than those observed in water due to the elasticity and viscosity of the medium. We further find that significant deviatoric stresses and increased heating in tissue are attributable to viscoelasticity, due to material properties and different bubble responses compared to water.
Non-reciprocal acoustic devices based on spatio-temporal angular-momentum modulation
Authors: Fleury Romain , Sounas Dimitrios , Alu Andrea
Published: October 2014

Acoustic devices that break reciprocity, for instance acoustic isolators or circulators, may find exciting applications in a variety of fields, including imaging, acoustic communication systems, and noise control. Non-reciprocal acoustic propagation has typically been achieved using non-linear phenomena, which require high input power levels and introduce distorsions. In contrast, we have recently demonstrated compact linear isolation for audible airborne sound by means of angular momentum bias [Fleury et al., Science 343, 516 (2014)], exploiting modal splitting in a ring cavity polarized by an internal, constantly circulating fluid, whose motion is imparted using low-noise CPU fans. We present here an improved design with no moving parts, which is directly scalable to ultrasonic frequencies and fully integrable. Instead of imparting angular momentum in the form of a moving medium as in our previous approach, we make use of spatio-temporal acoustic modulation of three coupled acoustic cavities, a strategy that can be readily implemented in integrated ultrasonic devices, for instance, using piezoelectric effects. In this new paradigm, the required modulation frequency is orders of magnitude lower than the signal frequency, and the modulation efficiency is maximized. This constitutes a pivotal step towards practically realizing compact, linear, noise-free, tunable non-reciprocal acoustic components for full-duplex acoustic communications and isolation.
Non contact ultrasound stethoscope
Authors: Jeger Nathan , Fink Mathias , Ing Ros Kiri
Published: October 2014

Heartbeat and respiration are very important vital signs that indicate health and psychological states of a person. Recent technologies allow to detect both physical parameters on a human subject by using different techniques with and without contact. Noncontact systems often use electromagnetic waves for contactless measurement but approaches based on ultrasound waves, laser or video processes are also proposed. In this abstract an alternative ultrasound system for non-contact and local measurement is presented. The system works in echographic mode and ultrasound signals are processed using two methods. The experimental setup uses an elliptic mirror to focus ultrasonic waves onto the skin surface. Backscattered waves are recorded by a microphone located close to the emitting transducer. Heartbeat and respiration signals are determined from the skin displacement caused by the chest-wall motion. For comparison purpose, the cross-correlation method, which uses broadband signal, and the Doppler method, which uses narrowband signal, are applied to measure the skin displacement. Sensitivity and accuracy parameters of the two methods are compared. At least, as the measurement is local, the system can act as a noncontact stethoscope to listen the internal sounds of the human body even through the light clothes of the patient.
High sensitivity imaging of resin-rich regions in graphite/epoxy laminates using joint entropy
Authors: Hughes Michael , McCarthy John , Marsh Jon , Wickline Samuel
Published: October 2014

The continuing difficulty of detecting critical flaws in advanced materials requires novel approaches that enhance sensitivity to defects that might impact performance. This study compares different approaches for imaging a near-surface resin-rich defect in a thin graphite/epoxy plate using backscattered ultrasound. The specimen, having a resin-rich void immediately below the top surface ply, was scanned with a 1 in. dia., 5 MHz center frequency, and 4 in. focal length transducer. A computer controlled apparatus comprised of an x-y-z motion controller, a digitizer (LeCroy 9400A), and an ultrasonic pulser/receiver (Panametrics 5800) was used to acquire data on a 100 ×100 grid of points covering a 3 × 3 in. square. At each grid point 256 512-word, 8-bit backscattered waveforms, were digitized, signal averaged, and then stored on computer for off-line analysis. The same backscattered waveforms were used to produce peak-to-peak, signal energy, as well as entropy images. All of the entropy images exhibit better border delineation and defect contrast than the either peak-to-peak or signal energy. The best results are obtained using the joint entropy of the backscattered waveforms with a reference function. Two different references are examined: a reflection from a stainless steel reflector, and an approximate optimum obtained from an iterative parametric search. The joint entropy images produced using the optimum reference exhibit ~3 times the contrast obtained in previous studies.
Determination of the characteristic impedance and the complex wavenumber of an absorptive material used in dissipative silencer
Authors: Lima Key F. , Barbieri Nilson , Barbieri Renato
Published: October 2014

The silencers are acoustic filters that have the purpose of reducing unwanted noise emitted by engines or equipment to acceptable levels. The vehicular silencers have large volume and dissipative properties. Dissipative silencers have absorptive material inside. These materials are typically fibrous and have good acoustic dissipation. However, few works depict the acoustic behavior of silencers with absorptive materials. The difficulty in evaluating this type of silencer is determining the acoustic properties of the absorptive material: the characteristic impedance and the complex wavenumber. This work shows an inverse methodology for determining the acoustic properties of the absorptive material used in silencers. First, it is found the silencer's acoustic efficiency in terms of the experimental sound transmission loss. Second, the absorptive material properties are determined with a parameters adjustment through a direct search optimization algorithm. In this step, the adjustment is done by applying The Finite Element Method in the search for the silencer's computational efficiency. The final step is to verify the difference between the experimental and computational results. For this work is used the acoustic efficiency of a silencer that has already been published in the literature. The results show good agreement.
Flat, lightweight, transparent acoustic transducers based on dielectric elastomer and gel
Authors: Jia Kun
Published: October 2014

The advances in flat-panel displays and Super Hi-Vision with a 22.2 multichannel sound system exhibit an entirely new viewing and listening environment for the audience; however, flat and lightweight acoustic transducers are required to fulfill this prospect. In this paper, a flat lightweight acoustic transducer with a rather simple structure is proposed. Polyacrylic elastomer membrane (VHB4905, 3M corporation) with 4 mm diameter, 0.5 mm thickness is biaxially prestretched and fixed on a polyurethane ring as the vibrator, then ionic gel is painted on the center region of the membrane as electrodes, finally, conducting wires which are also made by ionic gel is attached to the edge of the electrodes for applying the AC voltage with a DC bias. The ultrahigh transmittance of the VHB4905, gel, and polyurethane makes the transducer totally transparent, which is of great interest in advanced media technology. The dynamic properties of the membrane are studied experimentally along with its acoustic performance. It has been found that the behavior of the dielectric elastomer membrane is quite complicated, both of the in plane and out of plane vibration mode exist. The transducer shows better performance below 10 kHz for the low elastic modular of the membrane.
Bamboo musical instruments: Some physical and mechanical properties related to quality
Authors: Cottingham James P.
Published: October 2014

Bamboo is one of the most widely used materials in musical instruments, including string instruments and percussion as well as wind instruments. Bamboo pipe walls are complex, composed of a layered structure of fibers. The pipe walls exhibit non-uniformity in radial structure and density, and there is a significant difference between the elastic moduli parallel to and perpendicular to the bamboo fibers. This paper presents a summary of results from the literature on bamboo as a material for musical instruments. In addition, results are presented from recent measurements of the physical and mechanical properties of materials used in some typical instruments. In particular, a case study will be presented comparing measurements made on reeds and pipes from two Southeast Asian khaen. Of the two khaen discussed, one is a high quality khaen made by craftsmen in northeastern Thailand, while the other is an inexpensive instrument purchased at an import shop. For this pair of instruments, analysis and comparison have been made of the material properties of the bamboo pipes and the composition and mechanical properties of the metal alloy reeds.
Descriptive maps to illustrate the quality of a clarinet
Authors: Coyle Whitney L. , Guillemain Philippe , Doc Jean-Baptiste , Guilloteau Alexis , Vergez Christophe
Published: October 2014

Generally, subjective opinions and decisions are made when judging the quality of musical instruments. In an attempt to become more objective, this research presents methods to numerically and experimentally create maps, over a range of control parameters, that describe instrument behavior for a variety of different sounds features or “quality markers” (playing regime, intonation, loudness, etc.). The behavior of instruments is highly dependent on the control parameters that are adjusted by the musician. Observing this behavior as a function of one control parameter (e.g., blowing pressure) can hide diversity of the overall behavior. An isovalue quality marker can be obtained for a multitude of control parameter combinations. Using multidimensional maps, where quality markers are a function of two or more control parameters, can solve this problem. Numerically: in two dimensions, a regular discretization on a subspace of control parameters can be implemented while conserving a reasonable calculation time. However, in higher dimensions (if, for example, aside from the blowing pressure and the lip force, we vary the reed parameters), it is necessary to use auto-adaptive sampling methods. Experimentally: the use of an artificial mouth allows us to maintain control conditions while creating these maps. We can also use an instrumented mouthpiece: this allows us to measure simultaneously and instantly these control parameters and create the maps “on the fly.”
Recent works on the (psycho-)acoustics of wind instruments
Authors: Mamou-Mani Adrien
Published: October 2014

Two experiments aiming at linking acoustical properties and perception of wind instruments will be presented. The first one is a comparison between five oboes of the same model type. An original methodology is proposed, based on discrimination tests in playing conditions and default detection using acoustical measurements. The second experiment has been done on a simplified bass clarinet with an embedded active control system. A comparison of perceptual attributes, like sound color and playability, for different acoustical configurations (frequency and damping of resonances) is possible to test using a single system. A specific methodology and first results will be presented.
The importance of structural vibrations in brass instruments
Authors: Moore Thomas R. , Kausel Wilfried
Published: October 2014

It is often thought that the input impedance uniquely determines the quality of a brass wind instrument. However, it is known that structural vibrations can also affect the playability and perceived sound produced by these instruments. The processes by which the structural vibrations affect the quality of brass instruments are not completely understood, but it is likely that vibrations of the metal couple to the lips as well as introducing small changes in the input impedance. We discuss the mechanisms by which structural vibrations can affect the quality of a brass instrument and suggest methods of incorporating these effects into an objective assessment of instrument quality.
Chaotic behavior of the piccolo?
Authors: Giordano Nicholas
Published: October 2014

A direct numerical solution of the Navier-Stokes equations has been used to calculate the sound produced by a model of the piccolo. At low to moderate blowing speeds and at appropriate blowing angles, the sound pressure is approximately periodic with the expected frequency. As the blowing speed is increased or as the blowing angle is varied, the time dependence of the sound pressure becomes more complicated, and examination of the spectrum and the sensitivity of the sound pressure to initial conditions suggest that the behavior becomes chaotic. Similarities with the behavior found in Taylor-Couette and Rayleigh-Bènard instabilities of fluids are noted and possible implications for the nature of the piccolo tone are discussed.
Modeling the low-frequency response of an acoustic guitar
Authors: Shepherd Micah R.
Published: October 2014

The low-frequency response of an acoustic guitar is strongly influenced by the combined behavior of the air cavity and the top plate. The sound hole–air cavity resonance (often referred to as the Helmholtz resonance) interacts with the first elastic mode of the top plate creating a coupled oscillator with two resonance frequencies that are shifted away from the frequencies of the two original, uncoupled oscillators. This effect was modeled using finite elements for the top plate and boundary elements for the air cavity with rigid sides and back and no strings. The natural frequencies of the individual and combined oscillators were then predicted and compared to measurements. The model predicts the mode shapes, natural frequencies, and damping well thus validating the modeling procedure. The effect of changing the cavity volume was then simulated to predict the behavior for a deeper air cavity.
Experimental investigation of crash cymbal acoustic quality
Authors: Curley Devyn P. , Hanan Zachary A. , Luo Dan , Penny Christopher W. , Rodriguez Christopher F. , Lehrman Paul D. , Rogers Chris B. , White Robert D.
Published: October 2014

A methodology to quantitatively evaluate the quality of the transmitted acoustic signature of cymbals is under development. High speed video recordings of a percussionist striking both a Zildjian 14 in. A-custom crash cymbal and a Zildjian Gen 16 low volume 16 in. crash cymbal were recorded and used to determine biometrically accurate crash and ride striking motions. A two degree of freedom robotic arm has been developed to mimic human striking motion. The robotic arm includes a high torque elbow joint driven in closed loop trajectory tracking and an impedance controlled wrist joint to approximate the variable stiffness of the stick grip. A quantitative comparison of robotic and human strikes will be made using high speed video. Repeatable strikes will be carried out using the robotic system in an anechoic chamber for different grades of Zildjian cymbals, including low volume Gen 16 cymbals. Acoustic features of the measured sound output will be compared to seek quantitative metrics for evaluating cymbal sound quality that compare favorably with the results of qualitative human assessments that are currently in use by the industry. Preliminary results indicate noticeable differences in cymbal acoustic output including variations in modal density, decay time, and beating phenomena.
An open architecture for auralization of dynamic soundscapes
Authors: Aumann Aric R. , Chapin William L. , Rizzi Stephen A.
Published: October 2014

An open architecture for auralization has been developed by NASA to support research aimed at understanding human response to sound within a complex and dynamic soundscape. The NASA Auralization Framework (NAF) supersedes an earlier auralization tool set developed for aircraft flyover noise auralization and serves as a basis for a future auralization plug-in for the NASA Aircraft Noise Prediction Program (ANOPP2). It is structured as a set of building blocks in the form of dynamic link libraries, so that other soundscapes, e.g., those involving ground transportation, wind turbines, etc., and other use cases, e.g., inverse problems, may easily be accommodated The NAF allows users to access auralization capabilities in several ways. The NAF's built-in functionality may be exercised utilizing either basic (e.g., console executable) or advanced (e.g., MATLAB, LabView, etc.) host environments. The NAF’s capabilities can also be extended by augmenting or replacing major activities through programming its open architecture. In this regard, it is envisioned that third parties will develop plug-in capabilities to augment those included in the NAF.
Combining local source propagation modeling results with a global acoustic ray tracer
Authors: Williams Michael , Younk Darrel , Mattson Steve
Published: October 2014

A common method of sound auralization in large virtual environments is through acoustic ray tracing. The purpose of an acoustic ray tracer is to supply accurate source to listener impulse response functions for a virtual scene. Currently, sources are modeled as an omnidirectional point source in the ray tracer. This limits the fidelity of the results and is not accurate for complicated noise sources involving multiple audible parts. The proposed method is to simulate local source propagation to a sphere using various energy modeling techniques. These results may be used to increase the fidelity of a ray trace by giving directionality to the source and allowing for source audio to be mixed from recordings of components of the source. This is especially relevant when a full source has not yet been constructed. Because of this, there are many real world applications in engineering, architecture, and other fields that need high fidelity auralization of future products.
Modelling sound propagation in the presence of atmospheric turbulence for the auralization of aircraft noise
Authors: Rietdijk Frederik , Heutschi Kurt , Forssén Jens
Published: October 2014

A new tool for the auralization of aircraft noise in an urban environment is in development. When listening to aircraft noise sound level fluctuations caused by atmospheric turbulence are clearly audible. Therefore, to create a realistic auralization of aircraft noise, atmospheric turbulence needs to be included. Due to spatial inhomogeneities of the wind velocity and temperature in the atmosphere acoustic scattering occurs, affecting the transfer function between source and receiver. Both these inhomogeneities and the aircraft position are time-dependent, and therefore the transfer function varies with time resulting in the audible fluctuations. Assuming a stationary (frozen) atmosphere, the movement of the aircraft alone gives rise to fluctuations. A simplified model describing the influence of turbulence on a moving elevated source is developed, which can then be used to simulate the influence of atmospheric turbulence in the auralization of aircraft noise.
Simulation of excess ground attenuation for aircraft flyover noise synthesis
Authors: Tuttle Brian C. , Rizzi Stephen A.
Published: October 2014

Subjective evaluations of noise from proposed aircraft and flight operations can be performed using simulated flyover noise. Such simulations typically involve three components: generation of source noise, propagation of that noise to a receiver on or near the ground, and reproduction of that sound in a subjective test environment. Previous work by the authors focused mainly on development of high-fidelity source noise synthesis techniques and sound reproduction methods while assuming a straight-line propagation path with standard atmospheric absorption and simple (plane-wave) ground reflection models. For aircraft community noise applications, this is usually sufficient because the aircraft are nearly overhead. However, when simulating noise sources at low elevation angles, the plane-wave assumption is no longer valid and must be replaced by a model that takes into account the reflection of spherical waves from a ground surface of finite impedance. Recent additions to the NASA Community Noise Test Environment (CNoTE) software suite have improved real-time simulation capabilities of ground-plane reflections for low incidence angles. The models are presented along with the resulting frequency response of the filters representing excess ground attenuation. Discussion includes an assessment of the performance and limitations of the filters in a real-time simulation.
Evaluation of the perceptual fidelity of a novel rotorcraft noise synthesis technique
Authors: Hardwick Jonathan R. , Christian Andrew , Rizzi Stephen A.
Published: October 2014

A human subject experiment was recently conducted at the NASA Langley Research Center to evaluate the perceptual fidelity of synthesized rotorcraft source noise. The synthesis method combines the time record of a single blade passage (i.e., of a main or tail rotor) with amplitude and frequency modulations observed in recorded rotorcraft noise. Here, the single blade passage record can be determined from a time-averaged recording or from a modern aeroacoustic analysis. Since there is no predictive model available, the amplitude and frequency modulations were derived empirically from measured flyover noise. Thus, one research question was directed at determining the fidelity of four synthesis implementations (unmodulated and modulated main rotor only, and unmodulated and modulated main and tail rotor) under thickness and loading noise dominated conditions, using modulation data specific to those conditions. A second research question was aimed at understanding the sensitivity of fidelity to the choice of modulation method. In particular, can generic modulation data be used in lieu of data specific to the condition of interest, and how do modifications of generic and specific modulation data affect fidelity? The latter is of importance for applying the source noise synthesis to the simulation of complete flyover events.
Aeroacoustic response of coaxial Helmholtz resonators in a low-speed wind tunnel
Authors: Slaton William
Published: October 2014

The aeroacoustic response of coaxial Helmholtz resonators with different neck geometries in a low-speed wind tunnel has been investigated. Experimental test results of this system reveal strong aeroacoustic response over a Strouhal number range of 0.25–0.1 for both increasing and decreasing the flow rate in the wind tunnel. Ninety-degree bends in the resonator necks does not significantly change the aeroacoustic response of the system. Aeroacoustic response in the low-amplitude range has been successfully modeled by describing-function analysis. This analysis, coupled with a turbulent flow velocity distribution model, gives reasonable values for the location in the flow of the undulating stream velocity that drives vortex shedding at the resonator mouth. Having an estimate for the stream velocity that drives the flow-excited resonance is crucial when employing the describing-function analysis to predict aeroacoustic response of resonators.
Nonlinear self-sustained thermoacoustic instability in a combustor with three bifurcating branches
Authors: Zhao Dan , Li Shihuai
Published: October 2014

In this work, experimental investigations of a bifurcating thermoacoustic system are conducted first. It has a mother tube splitting into three bifurcating branches. It is surprisingly found that the flow oscillations in the bifurcating branches resulting from unsteady combustion in the bottom stem are at different temperatures. Flow visualization reveals that one branch is associated with “cold” pulsating flow, while the other two branches are “hot.” Such unique flow characteristics cannot be predicted by simply assuming the bifurcating combustor consisting of three curved Rijke tube. 3D Numerical investigations are then conducted. Three parameters are identified and studied one by one: (1) the heat source location, (2) the heat flux, and (3) the flow direction in the bifurcating branches. As each of the parameters is varied, the heat-driven acoustics signature is found to change. The main nonlinearity is identified in the heat fluxes. Comparing the numerical and experimental results reveals that good agreement is obtained in terms of mode frequencies, mode shapes, sound pressure level and supercritical Hopf bifurcating behavior.
Statistical inversion approach to estimating water content in an aquifer from seismic data
Authors: Lähivaara Timo , Dudley Ward Nicholas F. , Huttunen Tomi , Kaipio Jari P.
Published: October 2014

This study focuses on developing computational tools to estimate water content in an aquifer from seismic measurements. The poroelastic signature from an aquifer is simulated and methods that use this signature to estimate the water table level and aquifer thickness are investigated. In this work, the spectral-element method is used to solve the forward model that characterizes the propagation of seismic waves. The inverse problem is formulated in the Bayesian framework, so that all uncertainties are explicitly modelled as probability distributions, and the solution is given as summary statistics over the posterior distribution of parameters relative to data. For the inverse problem, we use the Bayesian approximation error method which reduces the overall computational demand. In this study, results in the two-dimensional case with simulated data are presented.
Surfactant-free emulsification in microfluidics using strongly oscillating bubbles
Authors: Ohl Siew-Wan , Tandiono Tandiono , Klaseboer Evert , Ow Dave , Choo Andre , Li Fenfang , Ohl Claus-Dieter
Published: October 2014

In this study, two immiscible liquids in a microfluidics channel has been successfully emulsified by acoustic cavitation bubbles. These bubbles are generated by the attached piezo transducers which are driven to oscillate at resonant frequency of the system (about 100 kHz) [1, 2]. The bubbles oscillate and induce strong mixing in the microchamber. They induce the rupture of the liquid thin layer along the bubble surface due to the high shear stress and fast liquid jetting at the interface. Also, they cause the big droplets to fragment into small droplets. Both water-in-oil and oil-in-water emulsions with viscosity ratio up to 1000 have been produced using this method without the application of surfactant. The system is highly efficient as submicron monodisperse emulsions (especially for water-in-oil emulsion) could be created within milliseconds. It is found that with a longer ultrasound exposure, the size of the droplets in the emulsions decreases, and the uniformity of the emulsion increases. Reference: [1] Tandiono, SW Ohl et al., “Creation of cavitation activity in a microfluidics device through acoustically driven capillary waves,” Lab Chip 10, 1848–1855 (2010). [2] Tandiono, SW Ohl et al., “Sonochemistry and sonoluminescence in microfluidics,” Proc. Natl. Acad. Sci. U.S.A. 108(15), 5996–5998 (2011).
Ultrasonic scattering from poroelastic materials using a mixed displacement-pressure formulation
Authors: denis Max , Nguon Chrisna , Chandra Kavitha , Thompson Charles
Published: October 2014

In this work, a numerical technique suitable for evaluating the ultrasonic scattering from a three-dimensional poroelastic material is presented. Following Biot’s derivation of the macroscopic governing equations for a fluid saturated poroelastic material, the predicted two propagating wave equations are formulated in terms of displacement and pressure. Assuming that porosity variations on a microscopic scale have a cumulative effect in generating a scattered field, the scattering attenuation coefficient of a Biot medium can be determined. The scattered fields of the wave equations are numerically evaluated as Neumann series solutions of the Kirchhoff-Helmholtz integral equation. A Padé approximant technique is employed to extrapolate beyond the Neumann series’ radius of convergence (weak scattering regime). In the case of bovine trabecular bone, the relationship between the scattering attenuation coefficient and the structural and mechanical properties of the trabecular bone is of particular interest. The results demonstrate the validity of the linear frequency-dependent assumption of attenuation coefficient n the low frequency range. Further comparisons, between measured observations and the numerical results will be discussed.
Cavity collapse in a bubbly liquid
Authors: Bolshakova Ekaterina S. , Kedrinskiy Valeriy
Published: October 2014

The effect of an ambient liquid state on a spherical cavity dynamics under atmospheric hydrostatic pressure p and extremely low initial gas pressure p(0) inside was investigated. The equilibrium bubbly (cavitating) medium with sound velocity C as the function of gas phase concentration k was considered as the ambient liquid model. The cavity dynamics is analyzed within the framework of Herring-equation for the following diapasons of main parameters : k = 0—5%, р(0) = 0.02—10(−6) atm. Numerical analysis has shown that the deceleration C by two order does not have an influence neither on an asymptotic value of collapsed cavity radius nor on the acoustical losses under its collapse. It means than in the whole the integral acoustical losses remain invariable. However the collapse cavity dynamics and the radiation structure are essentially changed: from numerous pulsations with a decreasing amplitudes up to a single collapse and from a wave packet up to a single wave, correspondingly. It has turned out that the acoustic corrections in the Herring-equation don’t influence practically on the cavity dynamics if the term of equation with dH/dt is absent. Naturally, the deceleration C exerts essential influence on an empty cavity dynamics. The graphs of dR/Cdt values as a function of R/Ro for different C values are located higher the data of classical models of Herring, Gilmore and Hunter. So the value M = 1 is reached at R/Ro = 0.023 for k = 0, and at the value 0.23 when k = 5 %. [Support RFBR, grant 12-01-00314.]
Age-related declines in hemispheric asymmetry as revealed in the binaural interaction component
Authors: Eddins Ann C. , Ozmeral Erol J. , Eddins David A.
Published: October 2014

The binaural interaction component (BIC) is a physiological index of binaural processing. The BIC is defined as the brain activity resulting from binaural (diotic or dichotic) stimulus presentation minus the brain activity summed across successive monaural stimulus presentations. Smaller binaural-induced activity relative to summed monaural activity is thought to reflect neural inhibition in the central auditory pathway. Since aging is commonly associated with reduced inhibitory processes, we evaluate the hypothesis that the BIC is reduced with increasing age. Furthermore, older listeners typically have reduced hemispheric asymmetry relative to younger listeners, interpreted in terms of compensation or recruitment of neural resources and considered an indication of age-related neural plasticity. Binaural stimuli designed to elicit a lateralized percept generate maximum neural activity in the hemisphere opposite the lateralized position. In this investigation, we evaluated the hypothesis that the BIC resulting from stimuli lateralized to one side (due to interaural time differences) results in less hemispheric asymmetry in older than younger listeners with normal hearing. Behavioral data were obtained to assess the acuity of binaural processing. Data support the interpretation that aging is marked by reduced central auditory inhibition, reduced temporal processing, and broader distribution of activity across hemispheres compared to young adults.
Effects of blast exposure on central auditory processing
Authors: Papesh Melissa , Gallun Frederick , Folmer Robert , Hutter Michele , Lewis M. Samantha , Belding Heather , Leek Marjorie
Published: October 2014

Exposure to high-intensity blasts is the most common cause of injury in recent U.S. military conflicts. Prior work indicates that blast-exposed Veterans report significantly more hearing handicap than non-blast-exposed Veterans, often in spite of clinically normal hearing thresholds. Our research explores the auditory effects of blast exposure using a combination of self-report, behavioral, and electrophysiological measures of auditory processing. Results of these studies clearly indicate that blast-exposed individuals are significantly more likely to perform poorly on tests requiring the use of binaural information and tests of pitch sequencing and temporal acuity compared to non-blast-exposed control subjects. Behavioral measures are corroborated by numerous objective electrophysiological measures, and are not necessarily attributable to peripheral hearing loss or impaired cognition. Thus, evidence indicates that blast exposure can lead to acquired deficits in central auditory processing (CAP) which may persist for at least 10 years following blast exposure. Future studies of these deficits in this and other adult populations are needed to address important issues such as individual susceptibility, anatomical, and physiological changes in auditory pathways which contribute to symptoms of these types of deficits, and development of effective evidence-based methods of rehabilitation in adult patients. [Work supported by the VA Rehabilitation Research & Development Service and the VA Office of Academic Affiliations.]
Acoustical bases for the perception of simulated laryngeal vocal tremor
Authors: Lester Rosemary A. , Story Brad H. , Lotto Andrew J.
Published: October 2014

Vocal tremor involves atypical modulation of the fundamental frequency (F0) and intensity of the voice. Previous research on vocal tremor has focused on measuring the modulation rate and extent of the F0 and intensity without characterizing other modulations present in the acoustic signal (i.e., modulation of the harmonics). Characteristics of the voice source and vocal tract filter are known to affect the amplitude of the harmonics and could potentially be manipulated to reduce the perception of vocal tremor. The purpose of this study was to determine the adjustments that could be made to the voice source or vocal tract filter to alter the acoustic output and reduce the perception of modulation. This research was carried out using a computational model of speech production that allows for precise control and modulation of the glottal and vocal tract configurations. Results revealed that listeners perceived a higher magnitude of voice modulation when simulated samples had a higher mean F0, greater degree of vocal fold adduction, and vocal tract shape for /i/ vs. /ɑ/. Based on regression analyses, listeners’ judgments were predicted by modulation information present in both low and high frequency bands. [Work supported by NIH F31-DC012697.]
A reduced-order three-dimensional continuum model of voice production
Authors: Zhang Zhaoyan
Published: October 2014

Although vocal fold vibration largely occurs in the transverse plane, control of voice is mainly achieved by adjusting vocal fold stiffness along the anterior–posterior direction through muscle activation. Thus, models of voice control need to be at least three-dimensional on the structural side. Modeling the detailed three-dimensional interaction between vocal fold dynamics, glottal aerodynamics, and the sub- and supra-glottal acoustics is computationally expensive, which prevents parametric studies of voice production using three-dimensional models. In this study, a Galerkin-based reduced-order three-dimensional continuum model of phonation was presented. Preliminary results showed that this model was able to qualitatively reproduce previous experimental observations. This model is computationally efficient and thus ideal for parametric studies in phonation research as well as practical applications such as speech synthesis. [Work supported by NIH.]
Impact of vocal tract resonance on the perception of voice quality changes caused by vocal fold stiffness
Authors: Signorello Rosario , Zhang Zhaoyan , Gerratt Bruce , Kreiman Jody
Published: October 2014

Experiments using animal and human larynx models are often conducted without a vocal tract. While it is reasonable to assume the absence of a vocal tract has only small effects on vocal fold vibration, it is unclear how sound production and its perception will be affected. In this study, the validity of using data obtained in the absence of a vocal tract for voice perception studies was investigated. Using a two-layer self-oscillating physical model, three series of voice stimuli were created: one produced with conditions of left-right symmetric vocal fold stiffness, and two with left-right asymmetries in vocal fold body stiffness. Each series included a set of stimuli created with a physical vocal tract, and a second set created without a physical vocal tract. Stimuli were re-synthesized to equalize the mean F0 for each series and normalized for amplitude. Listeners were asked to evaluate the three series in a sort-and-rate task. Multidimensional scaling analysis will be applied to examine the perceptual interaction between the voice source and the vocal tract resonances. [Work supported by NIH.]
The biological function of fundamental frequency in leaders' charismatic voices
Authors: Signorello Rosario
Published: October 2014

Charismatic leaders use voice based on two functions: a primary biological function and a secondary language and culture-based function (Signorello, 2014). In order to study the primary function in more depth, we conducted acoustic and perceptual studies on the use of F0 by French, Italian and Brazilian charismatic political leaders. Results show that leaders manipulate F0 in significantly different manners relative to: (1) the context of communication (persuasive goal, the place where communication occurs and the type of audience) in order to be recognized as the leader of the group; and (2) the elapse of time (from the beginning to the end of the speech) in order to create a climax with the audience. Results of a perceptual test show that the leader's use of low F0 voice results in the perception of the leader as a dominant or threatening leader and the use of higher F0 conveys sincere, calm, and reassuring leadership. These results show cross-language and cross-cultural similarities in leaders’ vocal behavior and listeners' perception, and robustly demonstrate the two different functions of leaders’ voices.
Voice quality variation and gender
Authors: Becker Kara , Khan Sameer ud Dowla , Zimman Lal
Published: October 2014

Recent work on American English has established that speakers increasingly use creaky phonation to convey pragmatic information, with young urban women assumed to be the most active users of this phonetic feature. However, no large-scale acoustic or articulatory study has established the actual range and diversity of voice quality variation along gender identities, encompassing different sexual orientations, regional backgrounds, and socioeconomic statuses. The current study does exactly that, through four methods: (1) subjects identifying with a range of gender and other demographic identities were audio recorded while reading wordlists as well as a scripted narrative assuming characters’ voices designed to elicit variation in vowel quality. Simultaneously, (2) electroglottographic readings were taken and analyzed to determine the glottal characteristics of this voice quality variation. (3) Subjects were then asked to rate recordings of other people’s voices to identify the personal characteristics associated with the acoustic reflexes of phonation; in the final task, (4) subjects were explicitly asked about their language ideologies as they relate to gender. Thus, the current study explores the relation between gender identity and phonetic features, measured acoustically, articulatorily, and perceptually. This work is currently underway and preliminary results are being compiled at this time.
Methodological issues when estimating subglottal pressure from oral pressure
Authors: Frazer Brittany , Scherer Ronald C.
Published: October 2014

A noninvasive method to estimate subglottal pressure for vowel productions is to smoothly utter a CVCV string such as /p:i:p:i:p:i:…/ using a short tube in the mouth with the tube attached to a pressure transducer. The pressure during the lip occlusion estimates the subglottal pressure during the adjacent vowel. What should the oral pressure look like for it to provide accurate estimates? The study compared results using various conditions against a standard condition that required participants to produce /p:i:p:i:../ syllables smoothly and evenly at approximately 1.5 syllables per second. The non-standard tasks were: performing the task without training, increasing syllable rate, using a voiced /b/ instead of a voiceless /p/ initial syllable, adding a lip or velar leak, or using a two syllable production (“peeper”) instead of a single syllable production. Lip leak, velar leak, and lack of time to equilibrate air pressure throughout the airway caused estimates of subglottal pressure to be inaccurate. Accuracy was better when estimates of subglottal pressure were obtained using the voiced initial consonant and the two-syllable word. Training improved the consistency of the oral pressure profiles and thus the assurance in estimating the subglottal pressure. Oral pressures with flat plateaus appear most accurate.
Reverberation data/model comparisons using transport theory
Authors: Thorsos Eric I. , Yang Jie , Henyey Frank S. , Elam W. T.
Published: October 2014

Transport theory has been developed for modeling shallow water propagation and reverberation at mid frequencies (1–10 kHz) where forward scattering from a rough sea surface is taken into account in a computationally efficient manner. The method is based on a decomposition of the field in terms of unperturbed modes, and forward scattering at the sea surface leads to mode coupling that is treated with perturbation theory. Reverberation measurements made during TREX13 combined with extensive environmental measurements provide an important test of transport theory predictions. Modeling indicates that the measured reverberation was dominated by bottom reverberation, and the reverberation level in the 2−4 kHz band was observed to decrease as the sea surface conditions increased from a low sea state to a higher sea state. This suggests that surface forward scattering was responsible for the change in reverberation level. Results of data/model comparisons examining this effect will be shown. [Work supported by ONR Ocean Acoustics.]