bluuebunny/crossref_metadata_2025 huggingface dataset:
Decrease of pitch perception ambiguity in tone language processing
Authors: Perdereau Xiao
Published: May 2013

Native tone language speakers were presented with speech materials in their language produced by non-native speakers. The speech materials were selected sound streams according to acoustic characteristics. They were made of monosyllabic words, disyllabic words and polysyllabic short sentences in spoken Mandarin. Participants were required to recognize the speeches in as short time as possible. Results revealed that the essential time to identify the speech is longer for shorter sequences, suggesting that ambiguities reside mostly in the lexical tone level. The ambiguity due to pitch perception decreases when the segmented speech events increase. Although it contributes to word meaning, pitch perception is less important in a polysyllables group of words or sentence processing than in monosyllabic word identification. We will also present some applications of these findings.
Fundamental frequency as cue to intonation: Focus on Ika Igbo and English rising intonation patterns
Authors: Uguru Joy O.
Published: May 2013

This paper shows that fundamental frequency, Fo, can be a cue to type of intonation. The work centers on three main intonation patterns in Ika Igbo and English. Ika Igbo is a language that manifests intonation in addition to lexical tone. These intonation patterns are Low Rise (LR), High Rise (LR), and Fall Rise (FR). The Fos of these intonation patterns were analyzed acoustically in utterances with similar phonemes and tunes in both languages. Eighteen utterances were used for the study. The analyses show that the Fos of LR and FR intonation were generally lower than those of HR. Hence, it can be concluded that high intonation has high Fo while low intonation has low Fo. It can therefore be concluded that Fo is a cue to type of intonation.
Downstep exceptions in Ibibio
Authors: Coombs Afton L.
Published: May 2013

Downdrift and downstep are processes which may cause lowering of high tone syllables. Downdrift is intonational, occurring at phrasal or utterance level, while downstep is a phonological process which acts from one tone-bearing unit to the next such that H tones lower successively. The relationship between these larger tonal lowering processes and individual tone units is complicated, however, by processes which may raise or preserve original high tone pitches. Ibibio, a Niger-Congo language spoken in southeastern Nigeria, is a terraced tone language with contrastive H and L tones. H tones in Ibibio experience automatic and non-automatic downstep, lowering both in sequences of high tones and around intervening lows. This study aims to determine those factors which counteract or overrule the downstep process. Average pitch readings were taken of entire syllables and compared with readings of other syllables within the same word. The main finding of this study is that while single words show acoustically measurable downtrends, they also show non-lowering and even raising of high tones, specifically in HHL contexts. This complicates how downtrends act across tone-bearing syllables, and may indicate that a high tone is raised in order to increase contrast with a following low.
Probabilistic two dimensional joint water-column and seabed inversion
Authors: Dettmer Jan , Dosso Stan E.
Published: May 2013

This paper develops a probabilistic two-dimensional (2D) inversion for geoacoustic seabed and water-column parameters in a strongly range-dependent environment. Range-dependent environments in shelf and shelf-break regions are of increasing importance to the acoustical-oceanography community, and recent advances in nonlinear inverse theory and sampling methods are applied here for efficient probabilistic inversion in 2D. The 2D seabed and water column are parameterized by highly efficient, self-adapting irregular grids which match the local resolving power of the data and provide parsimonious solutions requiring few parameters to capture complex environments. The self-adapting parameterization in the water-column and seabed is achieved by implementing the irregular grid as a trans-dimensional hierarchical Bayesian model which is sampled with the Metropolis-Hastings-Green algorithm. To improve sampling, population Monte Carlo is applied with a large number of interacting parallel Markov chains employing a loadbalancing algorithm on a computer cluster. The inversion is applied to simulated data for a vertical line array and several source locations to several kilometers range. Complex pressure fields are computed using a parabolic equation model and results are considered in terms of 2D ensemble parameter estimates and marginal uncertainty distributions. [Work supported by NSERC.]
Energy based Markov Chain Monte Carlo algorithms for Bayesian model selection
Authors: Jasa Tomislav , Botts Jonathan , Ning Xiang
Published: May 2013

Markov Chain Monte Carlo (MCMC) algorithms for Bayesian model selection have been increasingly applied to acoustics applications. One of challenging tasks required in Bayesian model selection is the exploration of high-dimensional multi-variate spaces such that a key quantity, termed the Bayesian evidence, can be estimated in order to rank a set of competing models. This work presents a class of energy-based MCMC algorithms specifically designed to estimate the Bayesian evidence. As illustrative examples, the energy-based MCMC algorithms are applied to the problem of filter design as used in human head-related transfer functions and in acoustic impedance boundaries within the finite-difference time-domain framework for room-acoustics simulations.
Nested sampling in practice
Authors: Botts Jonathan
Published: May 2013

For problems requiring both model comparison and parameter estimation, nested sampling is an attractive choice because it provides an estimate of the normalized posterior. The critical assumption of nested sampling is that exploration proceeds regularly toward the region of maximum likelihood. However, in practice, achieving such regular compression is far from trivial, particularly for realistic, multi-modal problems. This paper offers a comparison of both systematic and random walk exploration for generating samples within a constrained prior. Ranges for size of ensemble and amount of exploration required for regular compression are also established for different acoustic data analysis problems.
A Bayesian based equivalent sound source model for a military jet aircraft
Authors: Hart David M. , Neilsen Tracianne B. , Gee Kent L. , James Michael M.
Published: May 2013

The two-source model for jet noise holds that turbulent mixing noise in jets is generated by uncorrelated, fine-scale (FSS) and partially correlated, large-scale (LSS) turbulent structures [Tam et al., J. Fluid Mech. 615, 253–292, (2008)]. The noise from an F-22A Raptor is modeled with an equivalent source consisting of two line arrays of monopole sources. These arrays, one correlated and one uncorrelated, with Rayleigh distributed amplitudes, account for both FSS and LSS sound propagation [Morgan, J. Acoust. Soc. Am. 129, 2442 (2011)]. The equivalent source parameters are selected based on Bayesian methods implemented with simulated annealing and fast Gibbs sampler algorithms. This method yields the best fit parameters, and the sensitivity of the solution is indicated by the generated posterior probability distributions. Analysis of the resulting equivalent sources shows that the directional, correlated line array has a greater effect on the near field sound, and the sensitivity of the array's parameters increases as the frequency increases. This equivalent source model can generate results up to 2500 Hz and accurately predict both near field and far field measurements. The analysis suggests that the shape of the source distribution changes as the frequency increases. [Work sponsored by the Office of Naval Research.]
Assessing model uncertainties for joint inversions of seismological data using a genetic algorithm
Authors: Brownlow Priscilla , Brazier Richard , Nyblade Andrew , Julia Jordi , Boomer K. B.
Published: May 2013

Error bars were generated for velocity models using receiver functions and surface wave dispersion curves for four seismic stations in southern Africa, with a genetic algorithm adapted from the code NSGA-II. Each receiver function and dispersion curve was originally created by Eldridge Kgaswane (2009). We examined these stations, and through a series of statistical resampling, we were able to place an uncertainty on each layer’s velocity in the lithosphere. Each station was set to an initial model, which was perturbed to generate a series of best-fit models for the corresponding receiver functions and dispersion curves. For each layer of depth, a series of solutions evolve over a set number of generations using “survival of the fittest” to come up with these best-fit models. These were constrained to only consider geologically viable models, such as the velocity range in each layer and smoothing. Afterward, the error bounds on velocities were able to be placed on each layer. The velocity vs. depth plot gives the uncertainty from 1 to 2.5 km in depth. Now a better estimate of the velocities of the waves can be made, which leads to a better estimate of the composition of the lithosphere under southern Africa.
Application of statistical reduced isometry property to design of line arrays for compressive beamforming
Authors: Gaumond Charles F. , Edelmann Geoffrey F.
Published: May 2013

The Statistical Reduced Isometry Property (StRIP) and Statistical Null Space Property (SNSP) are presented and reduced to numerical algorithms. These properties are used to predict the utility of a specific subsampled array for use in compressive sensing. Three examples of subsampling an equally spaced array are presented: random, Golomb and Wichmann. The Golomb array uses a Golomb ruler that has no repeated sensor element spacings. The Wichmann array includes at least one of every possible interval of sensor element spacings. The SNSP is shown to be insensitive to subsampling in the type of cases shown. The Golomb array is predicted to have superior performance to the Wichmann for comparable subsampling. The use of these two subsamplings for beamforming using at-sea data from the Five Octave Research Array (FORA) is shown. [Research funded by the Office of Naval Research.]
Sensitivity of co-prime arrays to shape perturbation
Authors: Pyzdek Andrew T. , Culver R. Lee
Published: May 2013

Co-prime arrays offer savings in both implementation and computation by reducing the number of array elements. For passive beamforming, a pair of specially-spaced sparse arrays organized as a co-prime array provides unambiguous source bearings through the cancellation of the grating lobes inherent in the pattern response of each array if processed by itself. In the ocean environment, however, towed line arrays are difficult to keep aligned and take on a time-varying shape. Hodgkiss [IEEE JOE (1983)] showed that array shape perturbation can lead to beam broadening, an effect which may interfere with the grating lobe cancellation of co-prime arrays. In the present paper, performance degradation of co-prime sparse arrays are examined under the condition of perturbed array shape. Simulations are used to compare a co-prime array of known element spacing and position to an array with small uncertainties in both element location and interelement spacing along the array. Possible correction methods are examined. [Work sponsored by ONR Undersea Signal Processing.]
High resolution beamforming using sparse recovery from sensor array data
Authors: Menon Ravi , Gerstoft Peter
Published: May 2013

We consider the problem of adaptive beamforming using fewer snapshots than the number of sensors. Given an array of sensors in an environment and signals impinging on the array in the presence of background noise, it is of practical interest to be able to estimate the direction of arrival and power of the signals using as few snapshots as possible. In a sparse recovery framework, the signal vector is modeled as a sparse vector in the bearing domain. By casting the beamforming operation as an ℓ1 minimization problem (as opposed to the convention ℓ2 minimization), the signal vector can be recovered (the sensing matrix must satisfy the restricted isometry property). The results show an improvement over traditional beamforming methods and these are demonstrated using simulations.
Public space acoustics for information and safety
Authors: Tachibana Hideki
Published: May 2013

In such public-spaces as railway stations, airport terminal buildings, shopping arcade, etc., intelligible acoustic information is substantially needed as well as visual information. It is not only for announcements at ordinary times but for evacuation information at emergencies. In reality, however, there are many cases where the public address announcements are much deteriorated by reverberation and background noises in the spaces which results in poor aural intelligibility. In order to improve this kind of acoustic problems in public spaces, a comprehensive research is needed not only by building acoustics but also by speech science, electro-acoustics, signal-processing technology, and cognitive psychology. The acoustics research group in Chiba Institute of Technology, Japan, has been investigating this research topic these several years. In this presentation, the outline of this research and some of its outcome are introduced.
Analytic expression to derive the image source point between two symmetrical sloping planes
Authors: Ortiz Santiago , Svensson U. Peter , Cobo Pedro
Published: May 2013

The sound field in open cavities with sloping walls can be represented by image sources and edge diffraction components. Sloping walls will generate a systematic structure to the positions of the image source, and explicit expressions for those positions are presented here. Using such explicit expressions, rather than the general image source method, makes it straightforward to study arbitrarily high orders. When two opposite walls form parts of an infinite wedge, then their image sources will be positioned on a cylindrical surface. The addition of a floor is easy, while adding more walls requires an iterative procedure, with explicit visibility tests. First-order diffraction components can then be generated for each image source. Simulation results are compared with experimental measurements in a three dimensional open cavity with sloping walls.
Semi-anechoic music recording using multi-microphone technique to simulate orchestra directivity in room acoustic auralizations
Authors: Bassuet Alban A. , Caulkins Terence , Digerness Joseph , KnicKrehm Glenn
Published: May 2013

Over the last two decades, computer generated auralizations have become increasingly relevant to the design process of new performance spaces. Auralizations are based on anechoic material, and simulation realism is often limited by a small repertoire of recordings and the challenges of simulating an orchestra’s complex sound radiation characteristics. To address some of these issues, this paper describes a method to record—in semi-anechoic conditions—large musical ensembles for use in computer simulations. The method uses a multi-microphone hemispherical array distributed over an orchestra playing on a hard floor. A ray-tracing program models the orchestra as sectors of a hemisphere corresponding to each microphone location. Microphone signals are then mapped to their respective source sector. The method permits to record and simulate an entire orchestra with its directivity, including the movement of the musicians while playing. The paper describes the influence of the radius and angular resolution of the microphone array; it also investigates different source configurations in the computer model. The method has been implemented with renowned performers and orchestras and has been used for auralizations of several new concert hall design projects.
Mean-free-paths in concert and chamber-music halls and validation of the Sabine/Eyring equations for predicting their reverberation times
Authors: Beranek Leo L. , Nishihara Noriko
Published: May 2013

The Eyring/Sabine equations assume that in a large irregular room a sound wave travels in straight lines from one surface to another. It is assumed that the surfaces have an average sound absorption coefficient αav and that the average distance between reflections, i.e., the mean-free-path MFP, is 4V/Stot where V is the volume of the room and Stot is the total area of all of its surfaces. No account is taken of diffusivity of the surfaces. The 4V/Stot relation is based on experimental determinations in 11 very differently shaped rooms made by Vern Knudsen [Architectural Acoustics, (Wiley, 1932), pp. 132–141]. This paper sets out to test this relation experimentally for a wide variety of unoccupied concert and chamber music halls with seating capacities ranging from 200 to 15,000. To determine the MFP’s in them, the measured values of the sound strengths G and reverberation times RT were used. Computer simulations of the sound fields for several of these rooms were also made to determine the MFP’s. For these rooms, 4V/Stot is found to be an acceptable relation for MFP in the Sabine/Eyring equations.
Exploration of the differences between a pressure-velocity based in situ absorption measurement method and the standardized reverberant room method
Authors: Cats Peter , Tijs Emiel , Fernandez Comesana Daniel
Published: May 2013

Several measurement techniques are available for the determination of the sound absorbing properties of material packages. The Kundt’s method and the reverberant room method are the most commonly used techniques and they are standardized. However, both methods cannot be used in situ. In the past, it has been shown that the PU in situ method can be used in a broad frequency range (typically from 300 Hz up to 10 kHz), on small samples (typically 0.03 m2 to 0.38 m2 or larger), while hardly being affected by background noise and reflections. Several studies revealed that similar results can be obtained as with the Kundt’s tube if the measurements are performed under certain circumstances. A thorough comparison with the reverberant room method has not been conducted yet. In this paper, preliminary results are presented of a comparison of the reverberant room method, the PU in situ method, and measurements with PU probes in a reverberant room. Several factors that may cause discrepancies amongst the methods are discussed. In addition, edge effects, which are experienced with the reverberant room method due to the finite size of the sample, are visualized with 3D intensity measurements that are performed in a reverberant room.
The reverberation radius (rH) in an enclosure with asymmetrical absorption distribution
Authors: Arau–Puchades Higini , Berardi Umberto
Published: May 2013

This paper reviews the concept of the reverberation radius (rH) from the viewpoint of the classic theories of Sabine and Eyring. These theories are only valid when the sound field is uniformly distributed around a room, or in other words, when the energy density throughout a room is constant. Nevertheless, these theories have been applied to any spatial sound diffusion situation, also where this is not diffuse. For example, they are currently used in rooms with asymmetric absorption distribution. The limits of this approach also characterize the revised theory of Barron and more recent investigations. This paper proposes a solution to calculate the reverberation radius in rooms with non-uniformly distributed sound absorption (rH-ND).
How absorptive can a diffuser be to accurately measure random incidence scattering coefficients?
Authors: Schmich-Yamane Isabelle , Malgrange Marina , Rougier Christophe
Published: May 2013

In auditorium design, absorptive surfaces are as important as diffusive ones. Diffuse surface elements are rarely completely reflective. Absorption and scattering coefficients are not independent from each other. A real-size diffuser designed to be installed in a new auditorium under construction in France has been measured according to the ISO 17497-1 standard. This diffuser shows higher absorptiveness than any previously tested sample in CSTB's laboratory. The calculation of the random incidence scattering coefficient in the ISO 17497-1 standard is based on the Sabine equation for elements with αs less than 0.5. This paper presents how scattering coefficient calculations give incoherent results for more absorptive diffuse elements and proposes a new calculation method based on the Eyring equation. Measurement results obtained with both methods are presented and compared.
Prediction and measurement of the random incidence scattering coefficient of periodic reflective rectangular diffuser profiles
Authors: Schmich-Yamane Isabelle , Embrechts Jean-Jacques , Müller-Trapet Markus , Rougier Christophe , Vorländer Michael
Published: May 2013

Periodic reflective rectangular diffuser profiles have been previously studied by Embrechts through an analytical method calculating their random incidence scattering coefficients. This paper presents the results of further investigations obtained by real-scale and 1:5th scale random incidence scattering coefficient measurements on these profiles. All measurements were performed according to the corresponding ISO 354 and ISO 17497-1 standards. The measurement results are compared with the calculation results derived by the analytical method. Although some periodic profiles could not be treated by the analytical model, fairly good agreements are obtained between the different approaches. The real scale and 1:5th scale measurement results are also presented and compared.
Axial transmission measurements of guided modes on bone phantoms and in vitro human bone specimen
Authors: Minonzio Jean-Gabriel , Foiret Josquin , Talmant Maryline , Laugier Pascal
Published: May 2013

Cortical bone porosity has been evidenced as being a major if not the major “footprint” of bone loss and fragility. Several studies report that cortical bone behaves like a waveguide. Measurements of guided mode wavenumbers together with appropriate waveguide modeling have therefore the potential for providing estimations of effective stiffness coefficients (which are largely determined by cortical porosity) and also cortical thickness. However, data interpretation is challenging due to the heterogeneous, dissipative, and irregular nature of the wave guide. Moreover, surrounding and internal tissues modify the guided modes. This paper presents measurement of the wavenumbers of guided wave modes, using a multi-transmitter multi-receiver axial transmission probe. The method has been previously validated on isotropic elastic and visco-elastic plates covered by a soft tissue-mimicking layer. As an extension of our previous works, we have conducted in vitro experiments on (i) bone-mimicking tubes without and with soft-tissue mimicking layers and on (ii) human radius and tibia specimens. Despite challenging measurement conditions owing to low signal-to-noise ratio, guided mode wavenumbers have been successfully measured. The results were consistent with a free plate model. Data inversion led to an reasonably accurate estimate of the shell thickness and bulk velocities for all cases.
Ultrasound propagation through bone fractures with reamed intramedullary nailing: Results from numerical simulations
Authors: Catelani Fernanda , Ribeiro Ana Paula M. , Melo Carlos Alberto V. , Pereira Wagner C. , Machado Christiano B.
Published: May 2013

Low-intensity pulsed ultrasound stimulation (LIPUS) accelerates fracture healing, enhancing the release of inflammatory mediators and subsequent bone formation. The reamed intramedullary nailing (with the same diameter of the medullary cavity) is a surgical procedure widely used in Medicine. The aim of this work was to study ultrasound propagation inside fractures with and without reamed intramedullary nailing using 2D simulations. It was used a custom-made simulation code applied to numerical models (a 4-mm thick cortical plate, a medullary cavity with radius 4 mm with and without reamed nailing, and fracture gaps varying from 1 to 3 mm). A 1-MHz emitter was positioned above fracture center, and 14 receptor transducers were uniformly placed inside fracture gap. The acquired signals were used to estimate the time-of-flight of the first arriving signal (TOF) and the energy amplitude by means of the root mean square (RMS). TOF was slightly influenced by fracture gap variations. It was observed an increase in RMS values with the presence of metal nailing, due to the reflection in the interface water-metal. The receptors placed near cortical plates received more energy (constructive interference between the direct and lateral waves). For the case of reamed nailing, ultrasound stimulation may be intensified.
Computational simulations of time of flight and attenuation of first arriving signal from healing process of diaphyseal femur fractures
Authors: Rosa Paulo Tadeu C. , Pereira Aldo José F. , Pereira Wagner Coelho A.
Published: May 2013

Quantitative ultrasound (QUS) has been proposed to evaluate structural conditions from bone tissue in a non-invasive way. These techniques are based on the fact that the ultrasound propagation depends directly of tissues structures, so they carry information about them. Based on these arguments, the aim of this work was to estimate the time-of-flight (TOF) and attenuation of the first arriving signal (FAS) using computational simulations (Wave2000® CyberLogic, Inc., NY, EUA) in an axial transmission model in different kinds of fracture, during the healing process. In this work, we used QUS techniques to analyze the fracture healing process. The FAS has been chosen because it does not suffer interference of other waves since it is the first signal to arrive at the receiver. TOF increases immediately after bone fracture. When bone tissue starts to consolidate, TOF decreases and stabilizes with the same value of the intact bone. Attenuation is bigger in oblique and spiculate fracture than transversal ones for the same stage, which suggests that attenuation is sensitive to the kind of fracture. Other studies are being conducted to clarify this point.
Ultrasonic attenuation and speed in phantoms made of polyvinyl chloride-plastisol and graphite powder
Authors: Cortela Guillermo A. , Maggi Luis E. , Kruger Marco Antonio v. , Negreira Carlos A. , Pereira Wagner C A.
Published: May 2013

Biological phantoms are very useful for controlled experiments on biomedical ultrasound. Nevertheless they are normally made of organic materials with short time-duration. We have studied the ultrasonic properties of test-blocks made of polyvinyl chloride-plastisol (PVCP) that are very stable in time. In this work, we analyzed ultrasonic (US) attenuation and speed at 1 MHz, as a function of temperature (15–45°C) of five phantoms made with PVCP and different concentrations of graphite powder (0, 0.5, 1, 2, and 5%) using the classical transmission method. US speed diminishes almost linearly (from 1408 to 1333 m.s−1) as temperature increases. In general attenuation lied between 0.73 and 0.09 dB.cm−1, but presenting a more complex behavior. For graphite concentrations of 0.5 and 1%, attenuation was lower than for 0% and for the other two phantoms (2 and 5% concentrations) attenuation was higher. This behavior can be perhaps due to the fact that the fabrication temperature for 0.5 and 1% was 140°C and for the other was 170°C. Although the standard recipe is 170°C, we observed that smaller temperatures may add in adjusting the attenuation values and it is a very useful property to mimic different biological tissues. We are now working on multilayer phantoms of PVCP.
The effect of boundary proximity on the fundamental and subharmonic emissions from individual microbubbles at higher frequencies
Authors: Helfield Brandon , Leung Ben , Goertz David E.
Published: May 2013

It is recognized that the proximity of a boundary can influence the dynamic behavior of acoustically stimulated microbubbles. In a biomedical ultrasound context, this is relevant to molecular imaging with targeted microbubbles, and when microbubbles are near vessel walls or contained within microvessels. Theoretical models have recently been developed to examine these effects, but experimental work has been more limited and primarily focused on the assessment of resonant frequency effects rather than its impact on nonlinear behavior, which is perhaps more relevant to imaging applications. Understanding this behavior is important to improving microbubble detection and for the quantitative interpretation of contrast images. With the use of an optical trap, this study experimentally investigates the effect of boundary proximity (0 to 200 µm) and boundary stiffness (Opticell and agarose) on fundamental and subharmonic emissions from individual Definity and MicroMarker bubbles at 11 MHz. The scattered pressure dependence on proximity from an Opticell boundary resulted in an oscillatory dependence, while from an agarose boundary resulted in a decreasing fundamental and an increasing subharmonic response with increasing distance from the boundary. These experimental findings are not entirely captured by basic analytical simulations, likely suggesting that more complex numerical models may be required.
Bifurcation structure of the ultrasonically excited microbubbles undergoing buckling and rupture
Authors: Jafari Sojahrood Amin , Karshafian Raffi , C. Kolios Michael
Published: May 2013

Bubbles exposed to ultrasound are long known to exhibit highly nonlinear and chaotic dynamics. Bubbles stabilized by a shell material (MBs) are widely used as contrast agents in diagnostic ultrasound. However, the nonlinear behavior of the shell significantly increases the complexity of the dynamics. In order to realize the full potential of the MBs, better understanding of the MB behavior is necessary. In this study, the bifurcation structure of the MB with nonlinear shell behavior is investigated for the first time. The Marmottant model was numerically solved, and the bifurcation diagrams of the radial oscillations of the MB were plotted versus the control parameters (e.g., buckling radius). In agreement with recent experimental observations, results predict the generation of subharmonics at very low acoustic pressures. In addition, the numerical simulations predict the generation of higher order subharmonics (e.g., period 3) at very low acoustic pressures (<300 kPa and 25 MHz), which contradicts the predictions by free bubble and viscoelastic shell MB models. Results revealed the strong influence of the buckling and rupture radius on the order of the subharmonics. The numerical results were verified by experimental observations of higher order subharmonics in the oscillations of Definity at 25 and 55 MHz.
Ultrafast dynamics of the acoustic vaporization of phase-change microdroplets
Authors: Shpak Oleksandr , Stricker Laura , Kokhuis Tom , Luan Ying , Fowlkes Brian , Fabiilli Mario , Lohse Detlef , de Jong Nico , Versluis Michel
Published: May 2013

Superheated emulsion droplets are a promising tool for localized drug delivery. The physical mechanisms underlying the ultrasound-triggered vaporization of phase-change emulsions are largely unexplored. Here we study the acoustic vaporization of individual micron-sized perfluoropentane droplets at a nanoseconds timescale. The nucleation and growth of the vapor bubbles was imaged at frame rates up to 20 Mfps. The droplet vaporization dynamics was observed to have three distinct regimes: (1) prior to nucleation, a regime of droplet deformation and oscillatory translations; (2) a rapid growth of a vapor bubble enhanced by ultrasound-driven rectified heat transfer; and (3) a final phase characterized by a relatively slow expansion that is fully dominated by heat transfer. A method to measure the moment of inception of the nucleation event with respect to the phase of the ultrasound wave is proposed. A simple physical model captures quantitatively all of the features of the subsequent vapor bubble growth. In addition, we study the role of gas through a model for a vapor-gas bubble, including thermal diffusion and gas diffusion inside the liquid and we find good agreement with the experimental data. We underline the fundamental role of gas diffusion to prevent total recondensation of the bubble at collapse.
Temporal and spatial characteristics of nonlinear acoustic field generated by an extracorporeal shockwave therapy device: Modeling and measurements
Authors: Karzova Maria , Khokhlova Vera , Perez Camilo , Matula Thomas
Published: May 2013

Extracorporeal shock wave therapy (ESWT) refers to the use of focused shock pulses to treat certain musculoskeletal disorders. Although the technology is used clinically, acoustic characteristics of ESWT fields and their relation to the bioeffects induced are not fully understood. In the present work, the acoustic field of a clinical ESWT device (Duolith SD1) was characterized in water using a combined measurement and modeling approach. Simulation model was based on the nonlinear KZK equation; the boundary condition was based on the pressure waveforms measured in a plane 5 mm away from the therapy head. The model was used to simulate and to analyze pressure waveforms along the axis of the therapy head, 2D spatial distributions of peak pressures, and the shock structure. The modeling results were found in a good agreement with experimental data. Simulations performed for different initial source pressure amplitudes showed that a shock is not formed at the focus, even at the maximum operational level of the device. Predictions from the modeling at higher output settings suggest that a true shock would develop if the initial pressure output were doubled. [Work supported in parts by RFBR 12-02-31830 and 12-02-31418 grants and student stipend from the French Government.]
Dynamic time reversal acoustic focusing of ultrasound for biomedical applications
Authors: Sinelnikov Yegor D. , Sutin Alexander M. , Tsyuryupa Sergey Y. , Sarvazyan Armen P.
Published: May 2013

Time Reversal Acoustic (TRA) system provides effective focusing in inhomogeneous media that can be used in various biomedical applications including high intensity ultrasound treatment, ultrasound-assisted drug delivery, ultrasonic battery charging of implants, etc. In many cases, the TRA focusing is conducted in tissues with time varied properties and variation in propagating media degrades the TRA focused signal. Dynamic focusing is required to maintain the same acoustic intensity in the focus. We suggest adjustment to the radiated signal in order to maintain the maximal amplitude in the focus using the inverse filtering technique with Tikhonov regularization. The suggested algorithm enables to determine the radiated signal based on the changes in the focused signal received by a beacon. Developed algorithm of TRA refocusing was tested in the experiments with a TRA system with an aluminum reverberator comprising ten piezotransducers with resonance around 1 MHz, DAC control system and a multi-channel binary amplifier. This system was built in Artann Laboratories for investigation of time reversal acoustic focusing for hyperthermia therapy and drug delivery. The dynamic TRA refocusing is shown to be effective even in the case of significant lateral shifts in the media and strong focused signal variation.
Wearable long duration ultrasound therapy in rotator cuff tendinopathy
Authors: Lewis George , Hernanez Lyndon , Lewis George , Ortiz Ralph
Published: May 2013

Approximately one-third of the westernized adult population will experience some type of shoulder pain. The purpose of this pilot study was to evaluate a novel self-applied wearable therapeutic ultrasound device in the management of shoulder pain from rotator cuff tendinopathy. The Institutional Review Board of Cayuga Medical Center (CMC) approved this study and informed consent for the study was obtained from all subjects. The wearable ultrasound device provides 90 mW/cm2, 2.95 MHz, continuous-wave ultrasound for 5.5 h on a single charge. Four subjects meeting the studies inclusion criteria, presenting with rotator cuff tendinopathy, and demonstrating cognitive and functional ability to apply the pager-size device were enrolled at the outpatient physical therapy center of CMC. Subjects were instructed to wear the device for 3–4 h/day for 12 consecutive treatment sessions, and record their daily pain score on the visual analog scale (1 to 10) and global rate of health improvement scale (−7 to 7). Across the 12 treatments, subjects reported a 30% reduction in pain and 52% improvement in health compared to baseline scores (p < 0.05). The results of the pilot study indicate the device may be applied successfully and provides supportive evidence for a placebo controlled study.
Effects of median barriers on highway noise levels
Authors: Kim Jonghoon , Cohn Louis , Shu Ning
Published: May 2013

Median barriers are widely used on roadways in the United States. The main purpose of this paper was to evaluate a median barrier performance in reducing traffic noise using the latest FHWA Traffic Noise Model, TNM version 2.5. For this study, median barriers were modeled on three different roadway configurations—at grade, depressed, and elevated. The analysis results indicated that the range of insertion loss for a median barrier at grade was less than 1.5 dBA with a barrier height of 2.5 to 10 ft. The range of insertion loss for a median barrier on a depressed roadway (5, 10, and 20 ft below grade) was 0 to 2.8 dBA with a barrier height of 2.5 to 4.5 ft and insertion loss increased up to 4.3 dBA with a taller barrier height of 6 to 10 ft. On an elevated roadway (5, 10, and 20 ft above grade), the range of insertion loss for a median barrier was 0 to 1.7 dBA with a barrier height of 2.5 to 10 ft. Given the results of this research, it is reasonable to conclude that a standard median barrier would not provide a significant level of noise reduction. Furthermore, taller median barriers do not alter this conclusion. When considering the construction of very tall median barriers for noise reduction purposes, the costs would far outweigh the relatively minimal benefits of this approach.
Multichannel feedback control of interior road noise
Authors: Cheer Jordan , Elliott Stephen J.
Published: May 2013

Active noise control systems offer a potential method of reducing the weight of passive acoustic treatments and, therefore, increasing a vehicles’ fuel efficiency. The active control of engine noise can be implemented cost-effectively by using the car audio loudspeakers as control sources and an array of low-cost microphones as error sensors. Such systems have been commercially implemented, but without also controlling road noise their subjective benefits may be limited. The active control of road noise using a feedforward control strategy has also been practically demonstrated, but these systems require a number of accelerometers to be mounted to the vehicle’s structure to obtain a coherent reference signal and, therefore, lead to a significant implementation cost. This paper proposes a multichannel feedback system for the active control of road noise, which uses an array of microphones and car audio loudspeakers, which is common to a feedforward engine noise control system. The design of the multichannel feedback controller is described and its performance is validated using offline simulations employing data measured in a small city car.
Analysis of simulated flyover Contra Rotating Open Rotors noise data by using beamforming techniques for moving sources
Authors: Fleury Vincent , Chélius Alain
Published: May 2013

The relevance of beamforming techniques to analyze conventional airframe noise sources from flyover noise measurements is now well-known. With the development of Contra Rotating Open Rotors (CROR), the performance of such techniques needs to be assessed. To this aim, realistic ground CROR noise data are simulated. First, the flow is simulated by a U-Rans approach in the CROR frame. The front rotor consists of 11 blades and the rear rotor is composed of 9 blades. In addition, the incoming flow Mach number is M = 0.2. Then, the hydrodynamic blade pressure is propagated toward a ground microphone array by using the Ffowcs-Williams Hawkings' equation. The CROR follows an horizontal trajectory at constant speed (M = 0.2) and 150 m altitude. Finally, the microphone array data are analyzed by a conventional beamforming-based deconvolution technique for moving sources, DAMAS-MS. The results show that the amplitude of the harmonics of each blade passage frequency is correctly recovered. However, the amplitude of the interaction tones is badly estimated. To overcome this difficulty, the DAMAS-MS methodology, based on an acoustic source model constituted of uncorrelated monopoles, should be modified in order to introduce the correlation between the monopoles.
Real-time magnetic resonance imaging fo the upper airways during harmonica pitch bends
Authors: Egbert Peter R. , Shin Lewis K. , Barrett David , Rossing Thomas D. , Holbrook Andrew
Published: May 2013

Skilled harmonica players learn to bend the pitch of certain notes by a semitone or more, especially in blues playing, by adjusting the shape of their vocal tract [Bahnson et al., J. Acoust. Soc. 103, 2134 (2008)]. The changes of the vocal tract have been partially viewed with endoscopy and ultrasound but are still incompletely understood. While in a magnetic resonance imaging (MRI) scanner, a professional harmonica player using nonmagnetic, MRI-compatible diatonic harmonicas played draw and blow notes in both unbent and bent positions. Three-dimensional static and two-dimensional real-time magnetic resonance images of the upper airway were recorded in the sagittal and coronal planes. We identified and characterized the static and dynamic changes that facilitated pitch bends for low and high notes with specific attention to tongue positioning, tongue morphology, and airway shape. Deliberate changes in the tongue shape are often accompanied by changes in other parts of the vocal tract such as the pharynx.
The diverse environments multi-channel acoustic noise database: A database of multichannel environmental noise recordings
Authors: Thiemann Joachim , Ito Nobutaka , Vincent Emmanuel
Published: May 2013

Multi-microphone arrays allow for the use of spatial filtering techniques that can greatly improve noise reduction and source separation. However, for speech and audio data, work on noise reduction or separation has focused primarily on one- or two-channel systems. Because of this, databases of multichannel environmental noise are not widely available. DEMAND (Diverse Environments Multi-channel Acoustic Noise Database) addresses this problem by providing a set of 16-channel noise files recorded in a variety of indoor and outdoor settings. The data was recorded using a planar microphone array consisting of four staggered rows, with the smallest distance between microphones being 5 cm and the largest being 21.8 cm. DEMAND is freely available under a Creative Commons license to encourage research into algorithms beyond the stereo setup.
Variation of rhythm metrics in regional varieties of Acadian French
Authors: Cichocki Wladyslaw , Selouani Sid-Ahmed , Ayed Alaidine B. , Paulin Catherine , Perreault Yves
Published: May 2013

This preliminary investigation studies variation of rhythm metrics in dialects of Acadian French spoken in New Brunswick (Canada). The aim is to determine whether regional and social factors are significant sources of this variation. Data are recordings of 140 speakers who represent five geographic regions, both genders and two age groups (20–30 and 40–55 years of age). Sound files were segmented manually; eight interval-based metrics were calculated. Mean metric scores indicate that regional varieties of Acadian French pattern with other dialects of French; these scores are similar to those of other “syllable-timed” languages. Regional differences are found for several metrics (%V, Delta C, VarcoC, nPVI-C, rPVI-C), although the five geographic regions are not all clearly distinguished by these metrics. A major pattern that emerges is regional variation in high-vowel devoicing and/or deletion. Analyses also show that social factors are significant sources of interspeaker variability: gender (VarcoV, nPVI-C, rPVI-C) and age (DeltaV, VarcoV). These results suggest a certain amount of complementarity between regional and social factors in their effects on rhythm metrics.
Permanent noise and vibration monitoring as a valuable tool to the construction industry
Authors: Vaucher de la Croix Daniel , Freneat Christian
Published: May 2013

The construction of large infrastructures in dense urban areas comes along with a number of environmental challenges. Roads, railways, subways, and large building constructions necessarily have a significant impact on residents as well as surrounding buildings. This is especially true when it comes to consider large projects duration, which generally counts in months and even years. In this context, noise and vibration induced by the construction activities are major sources of annoyance to the community and may also induce potential damages to the immediate surroundings. Both issues have thus to be properly monitored in order to reduce adverse effects on residents, help mitigating risks and prevent potential interruption of the construction site's activity which would increase the overall project cost. The proposed paper will focus on how available communication technologies as an essential added value to noise and vibrations measurements. Operational conditions and project managers' requirements for system deployment will be reviewed. Then, benefits to the different parties will be highlighted on the basis of recent practical situations where adequate measures could be taken in the right timing and kept the project running while minimizing its noise and vibration environmental impact.
Modeling urban noise exposure and contribution of noise reflection against façades of buildings: Does correction matter?
Authors: Tenailleau Quentin M. , Bernard Nadine , Pujol Sophie , Joly Daniel , Houot Hélène , Mauny Frédéric
Published: May 2013

European noise directives advise to apply corrections when measuring and modeling noise levels close to a building in the aim of excluding the contribution of noise reflection against the façade. The advised +3 dB correction is still subject to discussion. In order to investigate the needed correction for an household exposure studies, a high definition noise model was used to estimate noise levels at 10,394 inhabitable buildings. Three buffers were used to sample area surrounding façades of buildings. The surfaces were defined between the following distances : (i) 0 and 2 m, (ii) 0 and 6 m, (iii) 2 and 6 m. No differences between the distribution structures were observed. Mean noise levels do not differ significantly between the buffers methods [respectively (i) 48.8±6.5 dB, (ii) 48.9±6.4 dB, (iii) 49.0±6.5 dB; p > 0.05]. Maximum noise levels differ significantly between the methods [respectively (i) 52.0±7.2 dB, (ii) 52.5±7.2 dB, (iii) 52.4±7.2 dB; p < 0.05]. These results show no or light differences between indices computed by the three sampling methods. They are in favour of no or at least a low correction value to deal with the contribution of noise reflection against the façade of a building.