bluuebunny/crossref_metadata_2025 huggingface dataset:
Production of prosodic cues by Beijing Mandarin speakers in second language (L2) English.
Authors: Barto-Sisamout Karen A.
Published: October 2013

Does the prosody of speakers’ first language (L1) influence their prosody in their second language (L2)? The current work investigates this topic for a tone language, Beijing Mandarin (BMan), as L1, and an intonation/stress language, English, as L2. English uses F0 contours as part of the intonation system, to signal syllabic prominence in a word, word prominence in a phrase, and the difference between questions and statements. In English there is a pitch peak delay, where the F0 peak occurs after the stressed syllable in two-syllable stress-initial words. Conversely, BMan uses F0 contours lexically, as a lexical tone language, and the F0 peak is on the stressed syllable. The production of these F0-related prosodic cues is investigated with BMan and Native English production of English narrow and broad focus statements and questions, with measurements of F0 contours on accented and unaccented words, pitch peak delay on accented words, and F0 levels in statements and questions. The goal is to learn if BMan speakers lexically specify tone of certain word types in English like in their L1, or realize F0 contours intonationally, like English speakers, or, finally, if they use an intermediate system different from L1 and L2.
The effect of oral proficiency on production of rhythm in spontaneous second language (L2) Japanese speech.
Authors: Shport Irina
Published: October 2013

This study addresses the question of whether oral proficiency in Japanese second language (L2) speech has a unique correlation with acoustic characteristics of rhythm production that is independent from segments. Among four rhythm measures used (V%, VarcoV, VarcoC, VI-M), only two measures were different for the spontaneous L2 Japanese speech of beginning and intermediate learners. The interlanguage rhythm of less proficient speakers of Japanese was characterized by lower variability in duration of vocalic stretches (VarcoV) and higher variability in duration of consonantal stretches (VarcoC), p < 0.05. For both VarcoV and VarcoC values, the distribution of the individual speakers’ rhythm scores was much tighter and on target for the intermediate students than for the beginning students. Furthermore, VarcoV values were significantly correlated with number of utterance-final vowels, and VarcoC values were correlated with number of obstruent clusters. In sum, the findings suggest that rhythmic differences in spontaneous L2 speech have an epiphenomenal nature stemming from the segmental structure of Japanese: the acquisition of mora-timed rhythm by learners of Japanese seems to be contingent upon the target-like production of segments which varies with proficiency level of learners.
Individual differences in the perception of vowels in a second language.
Authors: Lengeris A.
Published: October 2013

Individuals may differ in their ability to learn the sounds of a second language (L2), but the origin of this variability remains uncertain. The present study examined whether individual differences in L2 vowel processing are related to individual differences in L1 vowel and/or nonspeech processing. Greek learners of English were given a large battery of perceptual tests examining their (1) identification of natural Greek vowels in noise, (2) identification and discrimination of synthetic Greek vowels in quiet, (3) identification of natural English vowels in quiet and in noise, (4) identification and discrimination of synthetic English vowels in quiet, and (5) discrimination of a nonspeech (F2 only) continuum in quiet. Preliminary results show a large degree of variability between individuals not only in L2 but also in L1 and nonspeech tasks. However, despite this variability, the participants were consistent in their performance across speech and nonspeech tasks, a finding that supports an auditory acuity rather than a speech-specific explanation for the individual differences in performance found in the data.
Excitation of low frequency modes of solid cylinders by evanescent waves: Mode properties and coupling.
Authors: Espana Aubrey L. , Marston Philip L. , Williams Kevin L.
Published: October 2013

When using sound to detect objects buried beneath the seafloor, situations arise in which the incident acoustic wave has a significant evanescent component. This situation has been simulated in tank experiments [Osterhoudt et al., IEEE J. Ocean. Eng. (in press)] and the simulation was used to investigate scattering mechanisms. In prior work, the backscattering of evanescent and ordinary-propagating waves from small solid aluminum cylinders was studied [Espana and Marston, J. Acoust. Soc. Am. 124, 2584 (2008)]. It was determined that a strong low frequency mode could be excited when the cylinder was highly tilted in a horizontal plane. With increasing simulated burial depth, the spatial decay rate of the backscattering was enhanced compared to the spatial decay rate of the evanescent soundfield. This resonance has since been driven by evanescent waves when the cylinder is highly tilted in a vertical plane. This alternate method of excitation also showed an enhanced spatial decay rate with increasing simulated burial depth. FEM simulation of the free-field response of the cylinder reveals that this mode causes a rocking motion of each end of the cylinder and it is plausible that evanescent waves could also excite this type of response. [Work supported by ONR.]
Synthetic aperture sonar simulations of cylindrical targets.
Authors: Kargl Steven G. , Williams Kevin L. , Thorsos Eric I. , Lopes Joseph L.
Published: October 2013

Cylindrical targets of finite length can be used as reference targets not only for calibrating an existing SAS system, but more importantly, for testing new classification and identification algorithms. With only a few well-characterized measurements available for proud and buried cylindrical targets, numerical simulations of the acoustic response of these targets offer the potential to realize an unlimited set of target orientations with respect to the source and receiver locations. This paper discusses recent progress with our acoustic scattering models and the generation of a set of pings suitable for SAS processing. SAS images generated from numerical simulations are compared to SAS images generated from data collected during the recent pond experiment 2009 (Pondex09) at NSWC-PCD’s facility 383. The target is a solid aluminum cylinder with a 0.3 m diam and length of 0.61 m. [Work sponsored by ONR and SERDP.]
The broadband in-water structural acoustics of unexploded ordinance: Tank comparisons with at-sea rail measurements.
Authors: Simpson Harry J. , Houston Brian H. , Saniga Mike L. , Bucaro Joe A. , Berdoz Alain R. , Kraus Larry A.
Published: October 2013

Free field, proud, and buried laboratory measurements of unexploded ordinance (UXO) are compared to at-sea rail-based measurements of the same UXO. The Laboratory for Structural Acoustics (LSA) at the Naval Research Laboratory consists of a 1 million gallon, deionized water, indoor cylindrical tank (17 m diam by 15 m deep) and an indoor rectangular tank (10 m by 8 m) laboratory, with a 3 m deep sand bottom and 4 m of water column. These pristine laboratory measurements are used to explore the physical acoustics of the sound-structure interactions that can be used to validate models and to understand the structural acoustic features that may be measured in littoral environments. These laboratory results are compared and contrasted with measurements made on the same UXO in St. Andrews Bay near Panama City, Florida using a rail-based synthetic aperture sonar (SAS). The structural acoustics responses of the UXOs in this shallow water, 8 m deep, sandy-mud bottom environment are compared with the pristine results from the LSA. [Work supported by SERDP and ONR.]
An application of the finite difference time-domain method to the study of coupled volumes.
Authors: Botts Jonathan M. , Xiang Ning
Published: October 2013

A finite difference time domain (FDTD) scheme is applied to study the behavior of sound energy decay in coupled-volume systems. This particular method takes into account frequency dependent wall impedance as well as source characteristics. In time-domain method, impulse responses are direct results of numerical calculation and transient effects specific to coupled volumes can be visualized. In addition to examining traditional acoustic metrics, this model allows for the investigation of the sound energy flows in the system. The numerical calculations will also be compared with experimental scale model measurements. Though limited to low frequencies due to computational load, this method will demonstrate many advantages over geometric acoustic models and other wave based models for the study of coupled volumes.
One-dimensional transport equation models for sound energy propagation in long spaces.
Authors: Jing Yun , Larsen Edward , Xiang Ning
Published: October 2013

In this paper, a three-dimensional transport equation model is first presented to describe the sound energy propagation in a long space. Then the three-dimensional model is reduced to a one-dimensional model by approximating the solution using the method of weighted residuals. The one-dimensional transport equation model directly describes the sound energy propagation in the long dimension and deals with the sound energy across the cross-section by prescribed functions. The one-dimensional transport equation model consists of a coupled set of N transport equations. Only N = 1 and N = 2 are discussed in this paper. For larger N, although the accuracy could be improved, the calculation time is expected to be significantly longer, which diminishes the advantage of the one-dimensional model over the three-dimensional model in terms of the computational efficiency. Some simulation results are provided in comparison with the ray-tracing based approach, which show good agreement.
Reciprocal maximum-length and related sequences in the generation of natural, spatial sounding reverberation.
Authors: Trivedi Uday , Dieckman Eric , Xiang Ning
Published: October 2013

The development of artificial reverberation has made considerable progress in recent years. In this research, a unique approach utilizing reciprocal maximum-length sequences and related sequences is taken in generating a natural, spatial sounding reverberation. Additionally, an algorithm to shape and vary spaciousness within the context of an artificially generated reverberation is implemented. Results are verified through experimental measurements and subjective testing methods in a multichannel format. This work sheds light on alternative methods of generating artificial reverberation outside of commercially available systems. As a result, a direct application to room modeling techniques can be drawn with this work. Extensions of this research will comprise of investigations in objective and subjective behaviors of double-sloped energy decays in acoustically coupled spaces. From an educational perspective, outcomes of this research can serve as a foundation in ear-training for acoustics students seeking a broadened understanding of perceived reverberation in varying contexts.
Optimized overdetermination for interior Helmholtz problem coupled solvers.
Authors: Bockman Alexander , Calamia Paul , Xiang Ning
Published: October 2013

The use of points of overdetermination, so-called CHIEF points, in numerical solutions to exterior Helmholtz problems for the elimination of spurious modes is well established. Further, the number and relative position of such points in two-dimensional radially symmetric geometries has been demonstrated theoretically. Since CHIEF points require lower computational overhead than collocation nodes, strategic use represents an opportunity for the improvement of predictions with maximal efficiency. Given the differing uniqueness properties of solutions to the interior and exterior problems, the former allows for development of optimization in the absence of competing priorities. Theory for two- and three-dimensional analytical cases is developed and subsequently extended to general geometries. Localization with respect to subdomains of spatial decomposition is investigated as well.
Evaluation of the newly developed equation for noise barrier within an enclosed space.
Authors: Siu-Kit Lau , Lam Kwok-Wai
Published: October 2013

Indoor barrier can be employed to ensure the privacy of speech in open-plan offices and to shield the noise generated by the machines in plant rooms. However, existing publications on diffraction and noise reduction by barrier inside an enclosed space using the classical theory is limited by the assumption of diffuse field. Recently, a new formula for estimating the barrier insertion loss inside an enclosed space was proposed by Lau and Tang [J. Sound Vib. 20, 50–57 (2009)]. It is simple and is sufficiently accurate in engineering practice. In the present study, this new formula is proposed to estimate the insertion loss of a vertical partition between two flat rooms. The performance of the new formula is compared with that of the classical diffuse-field theory. The results indicate that the new formula provides more realistic and practical predictions of the insertion loss of the partition between two flat rooms than existing approaches. [The work described in this paper was supported by a grant from the Hong Kong Polytechnic University (Project A/C code: G-U362).]
Distinguishing FM-modulated bowhead whale calls from airgun and other biologic signals using image processing, feature extraction, and neural networks.
Authors: Thode Aaron , Mathias Delphine , Blackwell Susanna , Kim Katherine , Greene Charles
Published: October 2013

The detection and identification of repetitive or stereotyped bioacoustic signals in raw acoustic data are typically accomplished via matched filtering or spectrogram correlation techniques. However, the detection of FM-modulated sweeps that have variable frequency-modulated contours or bandwidths is still an active challenge. The problem is made more complex by the possible presence of other frequency-modulated signals such as airguns or other biologics. To provide a specific example, in 2007 and 2008 directional autonomous recording packages (DASARs) were deployed in the Beaufort Sea to monitor the annual migration of the bowhead whale (Balaena mysticetus) population during seismic exploration activities. A portion of these data sets has been manually analyzed, providing an opportunity to characterize the miss and false alarm rates of various FM-modulated detection and classification methods. Here literature and software on bioacoustic FM-contour tracing and classification are reviewed, with a particular emphasis on the use of contour tracing, image segmentation, feature extraction, and neural networks for identifying species-distinctive sounds. A combination of these methods, when applied to the Arctic data set, has been found to reduce the false alarm rate by a factor of 5, while preserving a miss rate of less than 20%. [Work supported by Shell Oil Co.].
A graph search algorithm for delphinid whistle contours.
Authors: Roch Marie A. , Patel Bhavesh , Soldevilla Melissa S. , Hildebrand John A.
Published: October 2013

A graph search algorithm is presented to extract tonal contours from audio signals in a fully automated manner. The algorithm is capable of tracking multiple contours simultaneously. Search is done in the spectral domain, with contours being treated as paths through a phase-magnitude space. A graph search formalism is combined with dynamic programming techniques to track candidate paths that may overlap or cross. Disambiguation of path crossings is accomplished by examining a combination of slope and the derivative of phase. The algorithm is general in nature and applicable to tonal calls from many animals with little modification. We target this work specifically toward delphinid whistles and demonstrate its efficacy on calls from bottlenose (Tursiops truncatus), short- and long-beaked common (Delphinus delphis and D. capensis), and Risso’s (Grampus griseus) dolphins recorded in the Southern California Bight. Characterizing the complete contour will permit the development of call comparison techniques that take into account finer grained detail than the typically used contour statistics (e.g., number of inflection points, minimum, and maximum frequencies). [This work is sponsored by the Office of Naval Research.]
Feature vector selection for identifying killer whale individuals.
Authors: Nichols Nicole , Atlas Les , Bowles Ann
Published: October 2013

One hindrance to studying whales is the simple act of identifying individuals. The source filter model of human speech is a potentially useful model for killer whale vocalizations. With this assumption, evaluation of vocal model based optimizations for human speaker recognition was performed with a whale dataset. (Twenty one calls of type 1a or 1b, from four captive Icelandic killer whales.) Feature vectors were extracted from sound samples, which reduce dimensionality while encapsulating the identifying characteristics. Recognition accuracy is highly dependent on choosing a feature vector, which can accurately divide the sample space. Cepstral coefficients are the standard used for human speaker recognition. Modulation envelopes are known to be important for perception and have been shown to improve speech recognition performance [Kingsbury et al., Speech Commun. 25, 117–132 (1998)]. Modulation spectrograms were examined and sampled across acoustic frequency at the fundamental modulation rate of the call to extract modulation feature vectors. Visual analysis of modulation spectrograms note a possible pattern unique to individual whales. Presented herein is analysis of these patterns based on linear discriminant functions and hidden Markov models. [Work supported by National Science Foundation Graduate Research Fellowship, University of Washington, Hubbs-Seaworld Research Institute.]
Parametric and holistic approaches to analyzing primate vocal signals for acoustic markers of caller identity, emotional state, and external context.
Authors: Rendall Drew , Vokey John
Published: October 2013

Vocal signals can be acoustically differentiated according to a variety of intrinsic and extrinsic dimensions. Among the most commonly investigated sources of signal differentiation in primates are those that mark the identity of the caller, potential variation in the caller’s underlying emotional or motivational state, and external environmental factors associated with signaling (e.g., the presense of predators or food). We analyzed a corpus of grunt vocalizations recorded from wild baboons for acoustic cues associated with these three dimensions. Grunts were collected from eight adult female baboons in two different behavioral contexts: 1. When approaching other females to handle their infants, and; 2. When embarking on an extended foraging excursion. Both contexts were further subdivided into conditions associated with low- versus high-arousal for callers. Analysis of the signals involved two different approaches: 1. A parametric analysis of specific acoustic features logically connected to either vocal-fold activity or supralaryngeal filtering (i.e., Fo and resonance properties) combined with principle components analysis (PCA) dimension reduction and discriminant analysis call classification; 2. A holistic analysis of the global spectral structure of entire signals that combined a PCA-based eigenvector decomposition and neural network classification of the calls. We compare results of the two analysis strategies.
Decoding the information contained in the alarm calls of Gunnison prairie dogs.
Authors: Slobodchikoff Con , Briggs William , Dennis Patricia
Published: October 2013

Gunnison prairie dogs have been shown to produce alarm calls that incorporate information about predators [Slobodchikoff et al., Anim. Behav. 42, 713–719 (1991)], such as the species of predator and also a description of the color and general size of the predator. The alarm calls contain a series of harmonics that encode this information. The calls have been analyzed with discriminant function analysis (DFA) and classification techniques such as self-organizing neural networks. These tools have been able to show that very specific information is encoded in the calls. However, exactly how this information is encoded into the signal has proven to be elusive. We show examples of the specific information that is encoded, and present a hypothetic model of how that information is encoded into the signals.
Temperature estimation and protocol assessment for monitoring high intensity focused ultrasound therapy with diagnostic ultrasound.
Authors: Speyer Gavriel , Kaczkowski Peter J. , Brayman Andrew A. , Crum Lawrence A.
Published: October 2013

Characterizing the performance of diagnostic ultrasound (DU) for monitoring high intensity focused ultrasound (HIFU) therapy is essential for identifying effective treatment protocols. Such protocols ensure accurate therapy monitoring in media with known thermal and perfusive properties. The protocols are specified by treatment duration, transducer motion, and the DU acquisition characteristics. The HIFU transducer is constrained to move in the plane perpendicular to its axis, with the DU positioned to capture the focal plane of the HIFU transducer. Differences in RF backscattering observed between two frames, one captured before and one after treatment, are known to result from a temperature distribution generated by the heat deposited during therapy. A functional expansion for the heating is used which provides minimum variance coefficient estimates for stationary backscattering by averaging the Fisher information matrix. We show through approximation, simulation, and experiment that these functions attain the Cramer-Rao bound independent of the particular heating applied or the RF backscattering encountered. Estimator accuracy is thus determined by the material properties, including the spatial correlation, and the protocol employed. Temperature estimates accurate to well within one degree Celsius are possible, and the estimation algorithm is implemented efficiently to enable near real-time monitoring. [Work supported by NIH Grant 5R01CA109557.]
Development of a tomographic cavitation sensor for quality assessment of clinical high intensity focused ultrasound systems.
Authors: Faragher Stuart , Gyöngy Miklós , Hodnett Mark , Shaw Adam , Coussios Constantin-C.
Published: October 2013

High-intensity focused ultrasound (HIFU) fields are known to nucleate and excite inertial and noninertial cavitation in tissue and tissue-mimicking materials once a threshold negative acoustic pressure is reached. In the context of ablative HIFU treatment, inertial cavitation has been correlated with significantly enhanced rates of heating, while in histotripsy, cavitation is the very mechanism that causes tissue damage. Characterizing the extent of the cavitation region produced by clinical HIFU devices is therefore important to ensure safe, efficient, and effective treatment. A novel, multielement sensor is being developed to enable accurate axial and radial mapping of the cavitation region during HIFU exposure by passive detection and tomographic reconstruction of the broadband emissions arising from bubble collapse. Computational modeling has shown that the application of a cross-correlation algorithm to simulated received signals has the potential to localise individual sources of emissions with submillimeter accuracy. Initial experimental validation of models has been conducted using a prototype device developed in collaboration with the National Physical Laboratory. Future work will involve the refinement of the sensor design and reconstruction algorithm to improve spatiotemporal resolution, along with the development of a tissue mimicking material which matches the acoustic properties and cavitation threshold of real tissue.
A Schlieren system for optical visualization of ultrasonic fields.
Authors: Kaczkowski Peter J. , Bailey Michael R. , Khokhlova Vera A. , Sapozhnikov Oleg A.
Published: October 2013

Ultrasonic field mapping is an essential component of transducer characterization and of beam forming verification. Such measurements are commonly performed by displacing a hydrophone over a range of points within the field; these procedures can be time-consuming. A calibrated hydrophone can provide accurate measurements of the field, subject to limitations of bandwidth and aperture of the device. A rapid qualitative 2D measurement of the spatial acoustic field can be obtained by optical means, in which the change in optical index due to the presence of acoustic pressure is imaged using a schlieren approach. This technique illuminates a transparent refracting acoustic medium using a plane collimated source and then focuses the transmitted light using a lens or mirror. In the absence of acoustic field, all of the light focuses to a small spot; acoustically induced refractive index perturbations cause some of the light to focus elsewhere. Obscuring the primary focal spot of unperturbed light with a mask permits imaging only the perturbations in the acoustic medium. We will describe a mirror-based schlieren system for imaging continuous as well as pulsed fields and with color corresponding qualitatively to the intensity of the field. [Work supported by NIH CA109556 and EB007643.]
The City of Portland responds to urban gentrification through an investigation of noise sources within the boundaries of north Portland neighborhoods.
Authors: Jenkins Adam C. , Wiebusch Julie A.
Published: October 2013

The North Portland area is a vibrant community, supporting residential populations, a wildlife reserve, and an active commerce. As Portland continues to attract new residents and residential areas expand in North Portland, the conflict between the residential desire for a peaceful environment and the commercial requirement to efficiently conduct business become more critical. The sustainability of the North Portland residential communites relies on planning decisions based on a well-defined understanding of the sound characteristics of the community. The City of Portland chose to study North Portland to better understand noise within its boundaries. The resulting noise mapping will serve as a tool for the City to use in future planning.
Sampling strategies for incorporating uncertainty and turbulent scattering into outdoor sound propagation calculations.
Authors: Lewis Matthew S. , Wilson D. Keith , Pettit Chris L.
Published: October 2013

The accuracy of mean sound-level estimates derived from different sampling methods is studied. The methods considered are Monte Carlo sampling (MCS), Latin Hypercube sampling (LHS), and Latinized Centroidal Voronoi Tessellation sampling (LCVTS). The goal is to determine which sampling method converges most rapidly to the actual mean sound level. The approach involves a model acoustic atmosphere, based on surface-layer similarity theory and a relaxation model for the ground, with sound fields calculated numerically with a parabolic equation solver. The range of consequences of epistemic uncertainty due to imperfect knowledge of the atmospheric and ground variables is examined through a simplified probabilistic model. Random (aleatory) uncertainty due to turbulent scattering also is considered. The samples are drawn randomly within the domain of uncertainty of the environmental variables. When only epistemic uncertainty is present owing to imprecise knowledge of the environmental variables, LCVTS is found to converge to an accurate estimate with the fewest number of samples, followed by LHS and then MCS. When random turbulent scattering is present, however, the sampling method has little effect on convergence.
Noise barriers based on recycled materials.
Authors: Sanchez-Dehesa Jose , Garcia-Chocano Victor , Torrent Daniel , Cervera Francisco , Cabrera Suitberto
Published: October 2013

Two-dimensional sonic crystals consisting of arrays of cylinders fabricated with recycled materials (rubber crumb) are proposed to reduce efficiently the noise. The attenuation by these barriers is produced by a combination of sound absorption by the rubber crumb and Bragg reflection by the ordered cylinders. Experiments performed in an anechoic chamber support the predictions by the multiple scattering theory. An optimization method is also reported to develop sound barriers for traffic noise. [Work supported by Spanish MICIIN.]
Pulse propagation in a hyperlattice.
Authors: Dickey Joseph
Published: October 2013

The classical dynamics and pulse propagation are presented for a series of latticelike structures whose spatial dimensionality ranges from one to four: four representing a hyperlattice. The lattices are connected 1-D wave bearing systems of varying lengths and can illuminate some aspects of higher dimension structures. Short pulses are launched at an arbitrary point, reverberate throughout the entire structure, and detected at another point. Some aspects of increasing dimensionality are illustrated with particular emphasis on the transition from three to four spatial dimensions. In a hypothetical 4-D world where only three are observable, the classical conservation laws and causality do not hold. The lack of causality is illustrated at each step in dimensionality by showing the “unexpected” pulse returns from the next higher dimension.
Scattering of compressional waves by a cavity in an elastic solid: Geometric interpretation and beam illumination.
Authors: Zhang Likun , Marston Philip L.
Published: October 2013

Aspects of the scattering of short-wavelength compressional waves by an empty spherical cavity in an elastic solid may be predicted geometrically from the elastic wave reflection coefficient for a plane surface and the curvature of the reflecting surface. When the outgoing wave is a shear wave, it is necessary to include the modified ray-tube parameters associated with mode conversion. Related geometrical considerations are also helpful for interpreting the scattering of a compressional wave Bessel beam by an empty spherical cavity centered on the beam in an elastic solid. The exact solution in that case follows from a generalization of the scattering analysis for acoustic Bessel beams [P. L. Marston, J. Acoust. Soc. Am. 121, 753–758 (2007)]. A modified analysis gives the directional dependence of the shear waves resulting from mode conversion for a cavity on the axis of a compressional wave Bessel beam. For both plane wave and Bessel beam illumination, the scattering pattern can depend strongly on the value of the Poisson ratio of the solid.
Acoustic cloaking in two and three dimensions.
Authors: Torrent Daniel , Sánchez-Dehesa José
Published: October 2013

The cloaking theory is analyzed in two and three dimensions. It is shown that cloaks require materials with some special properties not known in nature, mainly, they need to be fluid-like materials with anisotropic, inhomogeneous, and locally divergent acoustic properties. The anisotropy problem is solved with the help of the so-called “metamaterials”, the inhomogeneous behavior is implemented with stratified scatterers and the divergence of the parameters is avoided with the concept of “imperfect cloaks”, which transforms the scattering cross section of an object of radius R in that of an object of radius R′≪R. [Work supported by the Spanish MICIIN and the Consolider Program.]
Acoustic measurement of fines.
Authors: Carpenter Wayne , Wren Daniel , Kuhnle Roger , Chambers James
Published: October 2013

The measurement of sediment particles <100 microns in diameter suspended in water has received little attention; however, particles of this size can account for a large fraction of the material transported in streams and rivers. In order to advance the current state of knowledge, the use of acoustic techniques as a surrogate measurement for the concentration of fine sediment particles in water is investigated. Both backscatter and attenuation will be evaluated as potential measurement techniques using a laboratory tank. Based on experience with the use of 1–5 MHz frequencies for backscatter measurements of particles in the 100–1000 micron size range, initial work will focus on the use of a frequency of approximately 20 MHz. The attenuation and backscatter due to a range of concentrations of bentonite and kaolinite will be reported.
Direct numerical simulation of the acoustic virtual mass of granular media.
Authors: Calantoni Joseph , Hefner B. Todd
Published: October 2013

The theory of acoustic virtual mass in granular media hypothesizes that during sound propagation, energy is transferred out of the direction of propagation and into rotational and transverse degrees of freedom that act as an additional virtual mass, thus decreasing the sound speed. We use a discrete element model that explicitly simulates the motions and interactions of every particle in a finite volume to examine the theory of acoustic virtual mass. Simulations are fully three-dimensional where the physical properties, such as size, density, and shape (typically spherical), of every grain may be uniquely specified. Normal and tangential forces at grain-grain contact points are modeled with springs and friction, respectively. Depending on the material of interest (e.g., quartz grains), several normal contact force laws are available including linear elastic, linear elastoplastic, and Hertzian. Likewise, the tangential contact force is typically modeled with a stick-slip behavior using a linear spring and friction, but other variations are available. Sound speed and attenuation are calculated by propagation of pulses through the simulated materials and these results are compared to the predictions of theory with and without the virtual mass term.
Study of interface wave generation and shear wave velocity estimation.
Authors: Dong Hefeng , Chapman Ross
Published: October 2013

Estimation of the shear wave velocity profile versus depth and shear wave attenuation in the upper sediment layers has been an important research topic in underwater acoustics. The shear wave velocity profile is insensitive to hydrophone data measured in water column, while dispersion of the interface wave propagating along the water and sea bottom boundary (the Scholte wave) is closely related to shear wave velocity variation with depth in the upper sediment layers. However, due to the exponential decay of the amplitude of the interface waves, there may be no interface waves generated and recorded in a conventional underwater experiment configuration where the sources and receivers (vertical and/or horizontal hydrophone array) are located in the water column with distance (measured by wavelength of the interface wave) away from water bottom interface. In this paper the conditions in which interface waves can be generated, recorded, and visualized are studied by numerical experiments in the underwater environment. The conditions include source strength, frequency band, source–receiver configuration, and signal-to-noise ratio, etc. Examples are given for estimating of shear wave velocity profile with depth by inverting dispersion curves of recorded interface waves in real data. [Work supported by NFR under Contract No. 186923/I30.]
Perceptual adaptation to sinewave-vocoded speech across languages.
Authors: Bent Tessa , Loebach Jeremy L. , Phillips Lawrence , Pisoni David B.
Published: October 2013

Listeners rapidly adapt to many forms of degraded speech. What level of information drives this adaptation (e.g., acoustic, phonetic, lexical, syntactic), however, remains an open question. In the present study, three groups of listeners were passively exposed to sinewave-vocoded speech in one of three languages (English, German, or Mandarin) to manipulate the level(s) of information shared between the training languages and testing language (English). Two additional groups were also included to control for procedural learning effects. One control group received no training, while the other control group was trained with spectrally rotated English materials. After training, all listeners transcribed eight-channel sinewave-vocoded English sentences. The results demonstrated that listeners exposed to German materials performed equivalently to listeners exposed to English materials. However, listeners exposed to Mandarin materials showed an intermediate level of performance; their scores were not significantly different from the German or English groups but were also not significantly different from the two control groups. These results suggest that lexical access is not necessary for perceptual adaptation to degraded speech, but rather similar phonetic structure between the training and testing languages underlies adaptation to degraded speech. [Work supported by NIH-NIDCD T32 DC-00012 and R01 DC-000111.]
Assessment of perceptual assimilation before and after training.
Authors: Harnsberger James D.
Published: October 2013

Many non-native speech sounds are challenging to perceive and, ultimately, to acquire. The development of a model of cross-language speech perception and learning has been hampered by, among other issues, the high variability commonly observed in the perceptual assimilation of non-native contrasts due to phonetic context, talker, and a variety of indexical properties of speech. This variability may reflect persistent patterns in perception that influence learning, or it may represent only an early sensitivity to low-level phonetic detail that is attenuated as experience increases. To examine this issue, the perceptual assimilation by native speakers of American English of a variety of voicing and place contrasts from Hindi was assessed before and after training in a paired-associate word learning task. Training utilized tokens from four of the six talkers used in perceptual assimilation tasks. The purpose of the study was to determine whether or not assimilation patterns could be greatly modified and/or simplified over the course of word learning in the laboratory. If limited training resulted in large changes in perceptual assimilations, then models of cross-language speech perception and learning will need to rely on assimilation data elicited via procedures that result in stable and repeatable patterns.
Effects of “catch” trials on the discrimination of American English vowels by native Japanese speakers.
Authors: Nozawa Takeshi
Published: October 2013

Native Japanese speakers’ ability to discriminate American English vowels was tested in two different formats, in both of which they heard three stimuli per trial. The three stimuli in each trial were produced by three different talkers. In AXB format, subjects were to decide if the second stimulus included categorically the same vowel as the first or the third stimulus. In other words, the subjects knew that one of the three stimuli was categorically different from the other two. In the other format, the subjects heard three stimuli in each trial, and chose one stimulus that includes a categorically different vowel from the other two. Each vowel contrast was tested by different trials which contained an odd item out, and catch trials which contained three tokens each from each of the vowel contrast pairs. Subjects were visually presented with four boxes on a computer screen with the numbers 1, 2, and 3, and “No.” The “No” button was provided when no differences were detected The results reveal that with catch trials included, discriminating American English vowels is a lot more difficult. The results imply the Japanese subjects’ susceptibility to talker variance and inability to discriminate American English vowels categorically.
A closer look at perceptual epenthesis in cross-language perception.
Authors: Davidson Lisa , Shaw Jason
Published: October 2013

Previous studies have shown that listeners have difficulty distinguishing non-native CC sequences from their CVC counterparts (e.g. Japanese [ebzo]-[ebuzo], English [zgamo]-[zəgamo]). Some have argued that the phonology “repairs” non-native consonant clusters with vowel insertion (“perceptual epenthesis”), causing listeners to respond that CC and CVC sequences are the same. Production studies, however, have shown that speakers produce non-native CC sequences many ways, including epenthesis, changing C1, deleting C1, and prothesis. To test whether these other repairs of non-native clusters are also difficult to distinguish, English listeners (n=37) participated in an AX discrimination task that paired C1CVCV stimuli with CəCVCV (epenthesis), əCCVCV (prothesis), CVCV (deletion), or C2CVCV (C1 change). Each of these repairs caused some difficulty and there was an interaction between repair type and manner combination (stop-stop, stop-nasal, fricative-stop, fricative-nasal). Listeners were more accurate when C1 was deleted (81% accurate), followed by epenthetic and C1 changes (both 77%), then by prothesis (59%). Furthermore, compared to previous studies testing only the epenthetic repair, presenting listeners with various repair types dramatically improves discrimination in the epenthesis condition. These results indicate that perceptual epenthesis may be a task effect and that top-down phonological influences are more complex than previously assumed. [Research supported by NSF.]
Measuring sensitivity to short-term deviations in acoustic cue correlation.
Authors: Idemaru Kaori , Holt Lori L.
Published: October 2013

Listeners are sensitive to correlations among the multiple probabilistic acoustic cues that define speech categories. In English stop consonant productions, for example, fundamental frequency (f0) is strongly correlated with voicing. Reflecting this regularity, perception of syllables varying in voice onset time is shifted with changes in f0. Such sensitivity to the long-term regularities of a language must be balanced with enough flexibility that speech perception is able to accommodate deviations from these regularities, such as those that may arise variations from idiolect, dialect, or accented speech. The present experiments manipulate short-term acoustic cue correlations experienced in online perception to investigate the interplay between sensitivity to long-term and short-term acoustic cue correlation. Using overt categorization and eyetracking, the present results indicate that speech categorization is influenced by local shifts in acoustic cue correlations that deviate from long-term regularities of English. These experiments further examine the time course of this short-term learning and the degree to which it generalizes. The data suggest that listeners continually monitor speech input for regularity and tune online speech perception in relation to these regularities.
Proficiency instrumentation for cross language perception studies.
Authors: Bernstein Jared
Published: October 2013

Studies in cross language speech perception sometimes use self-reported values of language proficiency as an independent variable. In relation to other measurement methods, proficiency self-reports have been found susceptible to several sources of bias including demographic variables and proficiency level itself [S. Yamashita, Six Measures of JSL Pragmatics, U. Hawaii Press (1996)]. An inaccurate scaling of an independent variable can limit the precision of performance models that are based on that variable’s relation to the dependent variable. This paper presents a convenient method (Versant tests) for measuring spoken language proficiency that locates subjects on a 60 point scale with a standard error measurement of less than 3 points, thus reliably locating subjects into 20 levels along a linear continuum of proficiency. The testing procedure takes about 15 minutes to complete. The test-retest reliability of Versant scores for spoken English and Spanish are 0.97 and 0.96, respectively, both with correlations greater than 0.85 with independent human rated tests. The development, operation, and psychometric properties of the Versant tests are presented briefly, along with examples of their use in evaluating language instruction programs and standard listening comprehension tests.
On-line perception of lexical stress in English and Spanish: The effects of sentence intonation and vowel reduction.
Authors: Ortega-Llebaria Marta
Published: October 2013

Previous research shows that speakers of stress-accent languages rely on pitch-accents to perceive word stress in sentences spoken with declarative intonation, while in unaccented sentences, like post-focal contexts, they rely on other cues, i.e., duration in Spanish or vowel reduction in English. However, there is no experimental evidence on the effect that sentence intonation has in the “on-line” perception of word stress across languages. This experiment examines whether listeners detect word stress faster in unaccented stretches of speech that are preceded by a landmark in the sentence melody, i.e., the focal pitch-accent that always precedes a post-focal sentence, than in unaccented contexts not preceded by a landmark, i.e., reporting clauses. Results show that Spanish listeners identified target words at the beginning and end of post-focal contexts with similar reaction times, while in reporting clauses, target words placed at the end were identified faster than those placed at the beginning. Preliminary results for English show no significant differences. Thus, Spanish listeners re-weight cues to word stress on-line taking into account the patterns of sentence intonation. Sentence melody does not have such a strong effect in English, possibly because vowel reduction is a sufficient cue to an effective perception of word stress.
Asymmetries in the mismatch negativity response to vowels by French, English, and bilingual adults: Evidence for a language-universal bias.
Authors: Polka Linda , Molnar Monika , Baum Shari , Menard Lucie , Steinhauer Karsten
Published: October 2013

In infants, discrimination of a vowel change presented in one direction is often significantly better compared to the same change presented in the reverse direction. These directional asymmetries reveal a language-universal bias favoring vowels with extreme articulatory-acoustic properties (peripheral in F1/F2 vowel space). In adults, asymmetries are observed for non-native but not for native vowel contrasts. To examine neurophysiological correlates of these asymmetries we recorded MMN responses from monolingual (English, French) and simultaneous bilingual (English/French) adults using an oddball paradigm with four vowels: English [u], French [u], French [y], and an acoustically-distinct [y]. All vowels were tested in four conditions with each vowel serving as deviant and standard. Within each vowel pair, MMN responses were larger and earlier when the deviant vowel was more peripheral. This pattern was consistent across the language groups and was observed for within-category (within [u]; within [y]) and for cross-category vowel pairs ([u] versus [y]). Findings indicate that a bias favoring peripheral vowels is retained in the neural pre-attentive processing of vowels in adults. As in infant behavioral findings, this bias is independent of the functional status of the vowel pair. Implications for the natural referent vowel model [Polka and Bohn (2003)] will be discussed.