bluuebunny/crossref_metadata_2025 huggingface dataset:
Using ocean bottom seismometer networks to better understand fin whale distributions at different spatial scales
Authors: Weirathmueller Michelle , Wilcock William SD , Soule Dax C.
Published: October 2014

Ocean bottom seismometers (OBSs) are designed to monitor ground motion caused by earthquakes, but they also record low frequency vocalizations of fin and blue whales. Seismic networks used for opportunistic whale datasets are rarely optimized for acoustic localization of marine mammals. We demonstrate the use of OBSs for studying fin whales using two different networks. The first example is a small, closely spaced network of 8 OBSs deployed on the Juan de Fuca Ridge from 2003 to 2006. An automated method for identifying arrival times and locating fin whale calls using a grid search was applied to obtain 154 individual fin whale tracks over one year, revealing information on swimming patterns and spatial distribution in the vicinity of a mid ocean ridge. The second example is a network with widely spaced OBSs, such that a given call can only be detected on one instrument. The Cascadia Initiative Experiment is a sparse array of 70 OBSs covering the Juan de Fuca Plate from 2011 to 2015. Localization methods based on differential arrival times are not possible but techniques to locate the range and bearing to fin whales with a single OBS can be applied to constrain larger scale spatial distributions by comparing call densities in different regions.
Faster than real-time automated acoustic localization and call association for humpback whales on the Navy's Pacific Missile Range Facility
Authors: Helble Tyler A. , Ierley Glenn , D'Spain Gerald , Martin Stephen
Published: October 2014

Optimal time difference of arrival (TDOA) methods for acoustically localizing multiple marine mammals have been applied to the data from the Navy's Pacific Missile Range Facility in order to localize and track humpback whales. Modifications to established methods were necessary in order to simultaneously track multiple animals on the range without the need for post-processing and in a fully automated way, while minimizing the number of incorrect localizations. The resulting algorithms were run with no human intervention at computational speeds faster than the data recording speed on over 40 days of acoustic recordings from the range, spanning several years and multiple seasons. Spatial localizations based on correlating sequences of units originating from within the range produce estimates having a standard deviation typically 10 m or less (due primarily to TDOA measurement errors), and a bias of 20 m or less (due to sound speed mismatch). Acoustic modeling and Monte Carlo simulations play a crucial role in minimizing both the variance and bias of TDOA localization methods. These modeling and simulation techniques will be discussed for optimizing array design, and for maximizing the quality of localizations from existing data sets.
Tracking porpoise underwater movements in tidal rapids using drifting hydrophone arrays
Authors: Macaulay Jamie D. , Gillespie Doug , Northridge Simon , Gordon Jonathan
Published: October 2014

The growing interest in generating electrical power from tidal currents using tidal turbine generators raises a number of environmental concerns, including the risk that cetaceans might be injured or killed through collision with rotating turbine blades. To understand this risk we need better information on how cetaceans use tidal rapid habitats and in particular their underwater movements and dive behavior. Focusing on harbor porpoises, a European protected species, we have developed an approach which uses time of arrival differences of narrow band high frequency (NBHF) clicks detected on large aperture hydrophone arrays drifting in tidal rapids, to determine dive tracks of porpoises underwater. Probabilistic localization algorithms have been developed to filter echoes and provide accurate 2D or geo-referenced 3D locations. Calibration trials have been carried out that show that the system can provide depth and location data with submeter errors. Data collected over three seasons in tidal races around Scotland has provided new insights into how harbor porpoises are using these unique habitats, information vital for assessing the risk tidal turbines may pose.
Testing the beam focusing hypothesis in a false killer whale using hydrophone arrays
Authors: Kloepper Laura N. , Nachtigall Paul E. , Smith Adam B. , Buck John R. , Gaudette Jason E.
Published: October 2014

The odontocete sound production system is complex and composed of tissues, air sacs, and a fatty melon. Previous studies suggested that the emitted sonar beam might be actively focused, narrowing depending on target distance. In this study, we further tested this beam focusing hypothesis in a false killer whale (Pseudorca crassidens) in a laboratory setting. Using three linear arrays, we recorded the same emitted click at 2, 4, and 7 m distance while the animal performed a target detection task with the target distance varying between 2, 4, and 7 m. For each click, we calculated the beamwidth, intensity, center frequency, and bandwidth as recorded on each array. As the distance from the whale to the array increased, the received click intensity was higher than predicted by spreading loss. Moreover, the beamwidth varied with range as predicted by the focusing model and contrary to a piston model or spherical spreading. These results support the hypothesis that the false killer whale adaptively focuses its sonar beam according to target range. [Work supported by ONR and NSF.]
Obtaining underwater acoustic impulse responses via blind channel estimation
Authors: Rideout Brendan P. , Nosal Eva-Marie , Høst-Madsen Anders
Published: October 2014

Blind channel estimation is the process of obtaining the impulse responses between a source and multiple (arbitrarily placed) receivers without prior knowledge about the source characteristics or the environment. This approach could simplify localization of non-impulsive submerged sound sources (e.g., pinnipeds or cetaceans); the process of picking arrivals (direct and reflected) could be carried out on the estimated impulse responses rather than on the recorded waveforms, thus facilitating the use of time of arrival-based localization approaches. Blind channel estimation could also be useful in estimating the original source signal of a vocalizing animal through deconvolution of the estimated channel impulse responses and the recorded waveforms. In this paper, simulation and controlled pool studies will be used to explore requirements on source and environment characteristics and to quantify blind channel estimation performance for underwater passive acoustic applications.
Sustained acoustic medicine for stimulation of wound healing: A translational research report
Authors: Langer Matthew D. , Lewis George K.
Published: October 2014

The healing of both acute and chronic wounds is a challenging clinical issue affecting more than 6.5 million Americans. The regeneration phase of wound healing is critical to restoration of function, but is often prolonged because of the adverse environment for cell growth. Therapeutic ultrasound increases nutrient absorption by cells, accelerates cellular metabolism, and stimulates production of ECM proteins, which all increase the rate of wound healing. To test the effect of long duration ultrasound exposure, an initial study of wound healing was conducted in a rat model, with wounds sutured to prevent closure via contraction. In this study, a 6 mm wound healed in 9±2 days when exposed to 6 hours of ultrasound therapy, and 15±1 days with a placebo device (p<0.01). Following IRB approval of a similar protocol for use in humans, a case study was performed on the wound closure of a chronic wound. Four weeks of daily LITUS therapy reduced the wound size by 90% from its size after 21 days of treatment with standard of care. These results demonstrate the efficacy of long duration LITUS for healing wounds in an animal model and an initial case of healing in a human subject.
Characterizing the pressure field in a modified flow cytometer quartz flow cell: A combined measurement and model approach to validate the internal pressure
Authors: Perez Camilo , Wang Chenghui , MacConaghy Brian , Tu Juan , Swalwell Jarred , Matula Thomas J.
Published: October 2014

We incorporated an ultrasound transducer into a flow cytometer to "activate" microbubbles passing the laser interrogation zone (J. Acoust. Soc. Am. 126, 2954–2962, (2009)). This system allows high throughput recording of the volume oscillations of microbubbles, and has led to a new bubble dynamics model that incorporates shear thinning (Phys. Med. Biol. 58, 985–998 (2013)). Important parameters in the model include the ambient microbubble size, R0, driving pressure, PA, and the shell parameters χ and κ, the shell elasticity and viscosity, respectively. R0 is obtained by calibrating the cytometer. Pressure calibration is difficult because the flow channel width (<200µm) is too small to insert a hydrophone. The objective of this study was to develop a calibration method for a 20-cycle, 1 MHz transient pressure field. The pressure field propagating through the channel and into water was compared to a 3-D FEM model. After validation, the model was used to simulate the driving pressure as input for the bubble dynamics model, leaving only χ and κ variables. This approach was used to determine the mechanical properties for different bubbles (albumin, lipid, and lyzozyme shells). Excellent fits were obtained in many cases, but not all, suggesting heterogeneity in microbubble shell parameters.
Entropy based detection of molecularly targeted nanoparticle ultrasound contrast agents in tumors
Authors: Hughes Michael , McCarthy John , Marsh Jon , Wickline Samuel
Published: October 2014

In this study, we demonstrate the use of “joint entropy” of two random variables (X,Y) can be applied to markedly improve tumor conspicuity (where X = f(t) =backscattered waveform and Y = g(t) = a reference waveform; both differentiable functions). Previous studies have shown that a good initial choice of reference is a reflection of the original insonifying pulse taken from a stainless-steel reflector. Using this choice, joint entropy analysis is more sensitive to accumulation of targeted contrast agents than conventional gray-scale or signal energy analysis by roughly a factor of 2[Hughes, M. S., et al., J. Acoust. Soc. Am., 133(1), p 283, 2013]. We now derive an improved reference that is applied to three groups of (MDA-435, breast tumor) flank tumor-implanted athymic nude mice to identify tumor vasculature after binding perfluorocarbon nanoparticles (~250 nm) to neovascular avb3 integrins. Five mice received i.v.avb3-targeted nanoparticles, five received nontargeted nanoparticles, and five received saline at a dose of 1 ml/kg, which was allowed to circulate for up to two hours prior to imaging. Three analogous groups of nonimplanted mice were imaged in the same region following the same imaging protocol. Our results indicate an improvement in contrast by a factor of 2.5 over previously published results. Thus, judicious selection of the reference waveform is critical to improving contrast-to-noise in tumor environments when attempting to detect targeted nanostructures for molecular imaging of sparse features.
Thrombolytic efficacy and cavitation activity of rt-PA echogenic liposomes versus Definity exposed to 120-kHz ultrasound
Authors: Bader Kenneth B. , Bouchoux Guillaume , Holland Christy K. , Peng Tao , Klegerman Melvin E. , McPherson David D.
Published: October 2014

Echogenic liposomes can be used as a vector for co-encapsulation of the thrombolytic drug rt-PA and microbubbles. These agents can be acoustically activated for localized cavitation-enhanced drug delivery. The objective of our study was to characterize thrombolytic efficacy and sustained cavitation nucleation and activity from rt-PA-loaded echogenic liposomes (t-ELIP). A spectrophotometric method was used to determine the enzymatic activity of rt-PA released from t-ELIP and compared to unencapsulated rt-PA. The thrombolytic efficacy of t-ELIP, rt-PA alone, or rt-PA and the commercial contrast agent Definity® exposed to sub-megahertz ultrasound was determined in an in vitro flow model. Ultraharmonic (UH) emissions from stable cavitation were recorded during insonation. Both UH emissions and thrombolytic efficacy were significantly greater for rt-PA and Definity® over either rt-PA alone or t-ELIP with equivalent rt-PA loading. Furthermore, the enzymatic activity of t-ELIP was significantly lower than free rt-PA. When the dosage of t-ELIP was adjusted to compensate for the lack of enzymatic activity, similar thrombolytic efficacy was found for t-ELIP and Definity® and rt-PA. However, sustained ultraharmonic emissions were not observed for t-ELIP in the flow phantom.
Temporal stability evaluation of fluorescein-nanoparticles loaded on albumin-coated microbubbles
Authors: Gauthier Marianne , Kelly Jamie R. , O'Brien William D.
Published: October 2014

Purpose: This study aims to evaluate the temporal stability of newly designed FITC-nanoparticles (NPs) loaded on albumin-coated microbubbles (MBs) to be used for future drug delivery purposes. Materials and Methods: MBs (3.6 108 MB/mL) were obtained by sonicating 5% bovine serum albumin and 15% dextrose solution. NPs (5 mg/mL) were produced from fluorescein (FITC)-PLA polymers and functionalized using EDC/NHS. NP-loaded MBs resulted from the covalent linking between functionalized NPs and MBs via carbodiimide technique. Three parameters were quantitatively monitored over a 4-week duration at 8 time points: MB diameter was determined using a circle detection routine based on the Hough transform, MB number density was evaluated using a hemocytometer, and NP-loading yield was assessed based on the loaded-MB fluorescence uptake. Based on the hypotheses, analyses of variance or Kruskal Wallis test were run to evaluate the stability of these physical parameters over the time of the experiment. Results: Statistical analysis exhibited no significant differences in NP-loaded MB mean sizes, number densities, and loading yields over time (p > 0.05). Conclusion: Newly designed NP-loaded MBs are stable over at least a 4-week duration and can be used without extra precaution concerning their temporal stability. [This work was supported by NIH R37EB002641.]
Temperature dependence of harmonics generated by nonlinear ultrasound beam propagation in water
Authors: Maraghechi Borna , Kolios Michael C. , Tavakkoli Jahan
Published: October 2014

Ultrasound thermal therapy is used for noninvasive treatment of cancer. For accurate ultrasound based temperature monitoring in thermal therapy, the temperature dependence of acoustic parameters is required. In this study, the temperature dependence of acoustic harmonics was investigated in water. The pressure amplitudes of the transmitted fundamental frequency (p1), and its harmonics (second (p2), third (p3), fourth (p4), and fifth (p5)) generated by nonlinear ultrasound propagation were measured by a calibrated hydrophone in water. The hydrophone was placed at the focal point of a focused 5-MHz transducer (f-number 4.5) to measure the acoustic pressure. Higher harmonics were generated by transmitting a 5-MHz 15-cycle pulse that resulted in a focal positive peak pressure of approximately 0.26 MPa in water. The water temperature was increased from 26 °C to 52 °C in increments of 2 °C. Due to this temperature elevation, the value of p1 decreased by 9%±1.5% (compared to its value at 26 °C) and values of p2, p3, p4, and p5 increased by %5±2%, 22%±8%, 44%±7%, and 55%±5%, respectively. The results indicate that the nonlinear harmonics are highly temperature dependent and their temperature sensitivity increase with the harmonic number. It is concluded that the nonlinear harmonics could potentially be used for ultrasound-based thermometry.
Sound propagation in the presence of a resonant surface
Authors: Schwan Logan , Umnova Olga
Published: October 2014

The interactions between acoustic waves and an array of resonators are studied. The resonators are arranged periodically on an impedance surface so that the scale separation between sound wavelength and the array period is achieved. An asymptotic multi-scale model which accounts for viscous and thermal losses in the resonators is developed and is used to derive an effective surface admittance. It is shown that the boundary conditions at the surface are substantially modified around the resonance frequency. The pressure field on the surface is nearly canceled leading to a phase shift between the reflected and the incident waves. The array can also behave as an absorbing layer. The predictions of the homogenized model are compared with multiple scattering theory (MST) applied to a finite size array and the limitations of the former are identified. The influence of the surface roughness and local scattering on the reflected wave is discussed.
Cloaking non-spherical objects and collections of objects using the scattering cancelation method
Authors: Hicks Ashley J. , Guild Matthew D. , Haberman Michael R. , Alù Andrea , Wilson Preston S.
Published: October 2014

Acoustic cloaks can be designed using transformation acoustics (TA) to guide acoustic disturbances around an object. TA cloaks, however, require the use of exotic materials such as pentamode materials [Proc. R. Soc. A. 464, pp. 2411–2434, (2008)]. Alternatively, the scattering cancelation (SC) method allows the cloaked object to interact with the acoustic wave and can be realized with isotropic materials [Phys. Rev. B., 86, 104302 (2012)]. Unfortunately, SC cloaking performance may be degraded if the shape of the cloaked object diverges from the one for which the cloak was originally designed. This study investigates the design of two-layer SC cloaks for imperfect spherical objects. The cloaking material properties are determined by minimizing the scattered field from a model of the imperfect object approximated as a series of concentric shells. Predictions from this approximate analytical model are compared with three-dimensional finite element (FE) models of the cloaked and uncloaked non-spherical shapes. Analytical and FE results are in good agreement for ka ≤ 5, indicating that the SC method is robust to object imperfections. Finally, FE models are used to explore SC cloak robustness to multiple-scattering by investigating linear arrays of cloaked objects for different incident angles. [Work supported by ONR.]
Parity-time symmetric metamaterials and metasurfaces for loss-immune and broadband acoustic wave manipulation
Authors: Fleury Romain , Sounas Dimitrios , Alu Andrea
Published: October 2014

We explore the largely uncharted scattering properties of acoustic systems that are engineered to be invariant under a special kind of space-time symmetry, consisting in taking their mirror image and running time backwards. Known as Parity-Time symmetry, this special condition is shown here to lead to acoustic metamaterials that possess a balanced distribution of gain (amplifying) and loss (absorbing) media, at the basis of ideal loss-compensation, and under certain conditions, unidirectional invisibility. We have designed and built the first acoustic metamaterial with parity-time symmetric properties, obtained by pairing the acoustic equivalent of a lasing system with a coherent perfect acoustic absorber, implemented using electro-acoustic resonators loaded with non-Foster electrical circuits. The active system can be engineered to be fully stable and, in principle, broadband. We discuss the underlying physics and present the realization of a unidirectional invisible acoustic sensor with unique sensing properties. We also discuss the potential of PT acoustic metamaterials and metasurfaces for a variety of metamaterial-related applications, which we obtain in a loss-immune and broadband fashion, including perfect cloaking of sensors, planar focusing, and unidirectional cloaking of large objects.
Considerations for array design and inverse methods for source modeling of full-scale jets
Authors: Wall Alan T. , Harker Blaine M. , Stout Trevor A. , Gee Kent L. , Neilsen Tracianne B. , James Michael M.
Published: October 2014

Microphone array-based measurements of full-scale jet noise sources necessitate the adaptation and incorporation of advanced array processing methodologies. Arrays for full-scale jets measurements can require large apertures, high spatial sampling densities, and strategies to account for partially coherent fields. Many approaches have been taken to sufficiently capture radiated noise in past jet noise investigations, including patch-and-scan measurements with a small dense array, one-dimensional measurements along the extent of the jet in conjunction with an axisymmetric assumption, and full two-dimensional source coverage with a large microphone set. Various measurement types are discussed in context of physical jet noise field properties, such as spatial coherence, source stationary, and frequency content.
Toward the development of a noise and performance tool for supersonic jet nozzles: Experimental and computational results
Authors: Ruscher Christopher J. , Kiel Barry V. , Gogineni Sivaram , Magstadt Andrew S. , Berry Matthew G. , Glauser Mark N.
Published: October 2014

Modal decomposition of experimental and computational data for a range of two- and three-stream supersonic jet nozzles will be conducted to study the links between the near-field flow features and the far-field acoustics. This is accomplished by decomposing near-field velocity and pressure data using proper orthogonal decomposition (POD). The resultant POD modes are then used with the far-field sound to determine a relationship between the near-field modes and portions of the far-field spectra. A model will then be constructed for each of the fundamental modes, which can then be used to predict the entire far-field spectrum for any supersonic jet. The resultant jet noise model will then be combined with an existing engine performance code to allow parametric studies to optimize thrust, fuel consumption, and noise reduction.
Finely resolved spatial variation in F-22 spectra
Authors: Neilsen Tracianne B. , Gee Kent L. , Pope Hsin-Ping C. , Harker Blaine , James Michael M.
Published: October 2014

Examination of the spatial variation in the spectrum from ground-based microphones near an F-22 Raptor has revealed spectral features at high engine power that are not seen at intermediate power or in laboratory-scale jet noise. At military and afterburner powers, a double peaked spectrum is detected around the direction of maximum radiation. In this region, there is not a continuous variation in peak frequency with downstream distance, as seen in lab-scale studies, but a transition between the relative levels for two discrete one-third octave bands. Previous attempts to match similarity spectra for turbulent mixing noise to a few of these measurements split the difference between the two peak frequencies [Neilsen et al., J. Acoust. Soc. Am. 133, 2116–2125 (2013)]. The denser spatial resolution afforded by examining the spectral variation on all 50 ground-based microphones, located 11.6 m to the sideline and spanning 30 m, provides the opportunity to further investigate this phenomenon and propose a more complete formulation of expected spectral shapes. Special care must be given to account for the relative amount of waveform steepening, which varies with level, distance, and angular position. [Work supported by ONR.]
Experimental and computational studies of noise reduction for tactical fighter aircraft
Authors: Morris Philip , McLaughlin Dennis K. , Powers Russell , Sikarwar Nidhi , Kapusta Matthew
Published: October 2014

The noise levels generated by tactical fighter aircraft can result in Noise Induced Hearing Loss for Navy personnel, particularly those involved in carrier deck operations. Reductions in noise source levels are clearly necessary, but these must be achieved without a loss in aircraft performance. This paper describes an innovative noise reduction technique that has been shown in laboratory scale measurements to provide significant reductions in both mixing as well as broadband shock-associated noise. The device uses the injection of relatively low pressure and low mass flow rate air into the diverging section of the military-style nozzle. This injection generates “fluidic inserts” that change the effective nozzle area ratio and generate streamwise vorticity that breaks up the large scale turbulent structures in the jet exhaust that are responsible for the dominant mixing noise. The paper describes noise measurements with and without forward flight that demonstrate the noise reduction effectiveness of the inserts. The experiments are supported by computations that help to understand the flow field generated by the inserts as well as help to optimize the distribution and strength of the flow injection.
Where are the nonlinearities in jet noise?
Authors: Tinney Charles E. , Baars Woutijn J.
Published: October 2014

For some time now it has been theorized that spatially evolving instability waves in the irrotational near-field of jet flows couple both linearly and nonlinearly to generate far-field sound [Sandham and Salgado, Philos. Trans. R. Soc. Am. 366 (2008); Suponitsky, J. Fluid Mech. 658 (2010)]. An exhaustive effort at The University of Texas of Austin was initiated in 2008 to better understand this phenomenon, which included the development of a unique analysis technique for quantifying their coherence [Baars et al., AIAA Paper 2010–1292 (2010); Baars and Tinney, Phys. Fluids 26, 055112 (2014)]. Simulated data have shown this technique to be effective, albeit, insurmountable failures arise when exercised on real laboratory measurements. The question that we seek to address is how might jet flows manifest nonlinearities? Both subsonic and supersonic jet flows are considered with simulated and measured data sets encompassing near-field and far-field pressure signals. The focus then turns to considering nonlinearities in the form of cumulative distortions, and the conditions required for them to be realized in a laboratory scale facility [Baars, et al., J. Fluid Mech. 749 (2014)].
Characterization of supersonic jet noise and its control
Authors: Gutmark Ephraim , Cuppoletti Dan , Mora Pablo , Heeb Nicholas , Malla Bhupatindra
Published: October 2014

As supersonic aircraft and their turbojet engines become more powerful they emit more noise. The principal physical difference between the jets emanating from supersonic jets and those from subsonic jets is the presence of shocks in the supersonic one. This paper summarizes a study of noise reduction technologies applied to supersonic jets. The measurements are performed with a simulated exhaust of a supersonic nozzle representative of supersonic aircraft. The nozzle has a design Mach number of 1.56 and is examined at design and off-design conditions. Several components of noise are present including mixing noise, screech, broadband shock associated noise, and crackle. Chevrons and fluidic injection by microjets and a combination of them are shown to reduce the noise generated by the main jet. These techniques provide significant reduction in jet noise. PIV provides detailed information of the flow and brings out the physics of the noise production and reduction process.
Examining suprasegmental and morphological effects on constriction degree with ultrasound imaging
Authors: Davidson Lisa
Published: October 2014

Two case studies of ultrasound imaging use tongue shape differences to investigate whether suprasegmental influences affect the articulatory implementation of otherwise equivalent phonemic sequences. First, we examine whether word-medial and word-final stop codas have the same degree of constriction (e.g., "blacktop" vs. "black top"). Previous research on syllable position effects on articulatory implementation have conflated syllable position with word position, and this study investigates whether each prosodic factor has an independent contribution. Results indicate that where consistent differences are found, they are due not to the prosodic position but to speaker-specific implementation. Second, we examine whether morphological status influences the darkness of American English /l/ in comparing words like "tallest" and "flawless." While the intervocalic /l/s in "tall-est" and "flaw-less" are putatively assigned the same syllabic status, the /l/ in "tallest" corresponds to the coda /l/ of the stem "tall" whereas that of "flawless" is the onset of the affix "-less." Results indicate that /l/ is darker—the tongue is lower and more retracted—when corresponding to the coda of the stem word. Data in both studies were analyzed with smoothing spline ANOVA, an effective statistical technique for examining differences between whole tongue curves.
Imaging dynamic lingual movements that we could previously only imagine
Authors: Miller Amanda L.
Published: October 2014

Pioneering lingual ultrasound studies of speech demonstrated that almost the entire tongue could be imaged (McKay 1957). Early studies contributed to our knowledge of tongue shape and tongue bracing in vowels (Morrish et al. 1984; Stone et al. 1987). However, until recently, lingual ultrasound studies have been limited to standard video frame rates of 30 fps, which are sufficient only for imaging stable speech sounds such as vowels and liquids. High frame rate lingual ultrasound (>100 fps) allows us to view the production of dynamic speech sounds, such as stop consonants, and even click consonants. The high sampling rate, which yields an image of the tongue every 8–9 ms, improves image quality, by decreasing temporal smear, allowing even tongue tip movements to be visualized to a greater extent than was previously possible. Results from several high frame rate ultrasound studies (114 fps) of consonants that were collected and analyzed using the CHAUSA method (Miller and Finch 2011) are presented. The studies elucidate (a) tongue dorsum and root gestures in velar and uvular pulmonic consonants; (b) tongue coronal, dorsal, and root gestures in four contrastive click consonants; and (c) lingual gestures in pulmonic fricatives.
Ultrasound evidence for place of articulation of the mora nasal /ɴ/ in Japanese
Authors: Mizoguchi Ai , Whalen Douglas H.
Published: October 2014

The Japanese mora nasal /ɴ/, which occurs in syllable-final position, takes its place of articulation from the following segment if there is one. However, the mora nasal in utterance-final position is often transcribed as velar, uvular, or even placeless. The present study examines the tongue shapes in Japanese using ultrasound imaging to investigate whether Japanese mora nasal /ɴ/ is placeless and to assess whether assimilation to following segments is gradient or categorical. Preliminary results from ultrasound imaging from one native speaker of Tokyo dialect showed three shapes for final /ɴ/, even though the researchers could not distinguish them perceptually. Results from assimilation contexts showed that the velar gesture for /ɴ/ was not deleted. All gestures remained and assimilation was not categorical, even though perceptually, it was. The velar gesture for /ɴ/ might be expected to be deleted before an alveolar /n/ because they are both lingual, but a blending of the two tongue gestures occurred instead. Variability in place of articulation in final position occurred even within one speaker. Categorical assimilation was not observed in any phonological environments studied. The mora nasal may vary across speakers, so further research is needed to determine whether it behaves similarly for more speakers.
A multi-modal imaging system for simultaneous measurement of speech articulator kinematics for bedside applications in clinical settings
Authors: Conant David F. , Bouchard Kristofer E. , Gopala Anumanchipalli K. , Dichter Ben , Chang Edward F.
Published: October 2014

A critical step toward a neurological understanding of speech generation is to relate neural activity to the movement of articulators. Here, we describe a noninvasive system for simultaneously tracking the movement of the lips, jaw, tongue, and larynx for human neuroscience research carried out at the bedside. We combined three methods previously used separately: videography to track the lips and jaw, electroglottography to monitor the larynx, and ultrasonography to track the tongue. To characterize this system, we recorded articulator positions and acoustics from six speakers during production of nine American English vowels. We describe processing methods for the extraction of kinematic parameters from the raw signals and methods to account for artifacts across recording conditions. To understand the relationship between kinematics and acoustics, we used regularized linear regression between the vocal tract kinematics and speech acoustics to identify which, and how many, kinematic features are required to explain both across vowel and within vowel acoustics. Furthermore, we used unsupervised matrix factorization to derive "prototypical" articulator shapes, and use them as a basis for articulator analysis. These results demonstrate a multi-modal system to non-invasively monitor speech articulators for clinical human neuroscience applications and introduce novel analytic methods for understanding articulator kinematics.
Combined analysis of real-time three-dimensional tongue ultrasound and digitized three-dimensional palate impressions: Methods and findings
Authors: Lulich Steven M.
Published: October 2014

Vocal tract and articulatory imaging has a long and rich history using a wide variety of techniques and equipment. This presentation focuses on combining real-time 3D ultrasound with high-resolution 3D digital scans of palate impressions. Methods for acquiring and analyzing these data will be presented, including efforts to accomplish 3D registration of the tongue and hard palate. Findings from an experiment investigating inter-speaker variability in palate shape and vowel articulation will also be presented.
AutoTrace: An automatic system for tracing tongue contours
Authors: Hahn-Powell Gustave V. , Archangeli Diana
Published: October 2014

Ultrasound imaging of the tongue is used for analyzing the articulatory features of speech sounds. In order to be able to study the movements of the tongue, the tongue surface contour has to be traced for each recorded image. In order to capture the details of the tongue’s movement during speech, the ultrasound video is generally recorded at the highest frame rate available. Detail comes at a price. The number of frames produced from even a single non-trivial experiment is often far too large to trace manually. The Arizona Phonological Imaging Lab (APIL) at the University of Arizona has developed a suite of tools to simplify the labeling and analysis of tongue contours. AutoTrace is a state-of-the-art automatic method for tracing tongue contours that is robust across speakers and languages and operates independently of frame order. The workshop will outline the software installation procedure, introduce the included tools for selecting and preparing training data, provide instructions for automated tracing, and overview a method for measuring the network’s accuracy using the Mean Sum of Distances (MSD) metric described by Li et al. (2005).
UATracker: A tool for ultrasound data management
Authors: Mahdavi Mazdeh Mohsen , Archangeli Diana B.
Published: October 2014

This presentation introduces TraceTracker, a tool for efficiently managing language ultrasound data. Ultrasound imaging of the tongue is used for analyzing the articulatory features of speech sounds. Most analyses involve finding data points from individual images. The number of image frames and the volume of secondary data associated with them tend to grow quickly in speech analysis studies of this type, making it very hard to handle them manually. TraceTracker is a data management tool for organizing, modifying, and performing advanced searches over ultrasound tongue images and the data associated with those images. The setup operation of the program automatically iterates through file systems and generates a comprehensive database containing the image files and information such as the speaker, the video each frame is extracted from, an index, how they have been traced, etc. The program also automatically reads Praat format TextGrid files and associates specific image frames with the corresponding words and speech segments based on the annotations in the grids. Once the database is populated, TraceTracker can be used to tag images, generate copies, and perform advanced search operations over the images based on the aforementioned criteria including the specific sequence of segments in which it lies.
Optical flow analysis for measuring tongue-motion
Authors: Barbosa Adriano V. , Vatikiotis-Bateson Eric
Published: October 2014

Most attempts to measure motion of the tongue have focused on locating the upper surface of the tongue or specific points on that surface. Recently, we have used our software implementation of optical flow analysis, FlowAnalyzer, to extract measures of tongue motion. The software allows identification of multiple regions of interest, consisting of rectangles whose dimensions and location are user-definable. For example, a large region encompassing the visible tongue body provides general information about the amount and direction (2D) of motion through time; while narrow vertical rectangles can measure the time-varying changes of tongue height at various locations. We will demonstrate the utility of the software, which is freely available upon request to the authors.
The influence of lexical status in the perception of English allophones by Korean learners
Authors: Kim Kyung-Ho , Han Jeong-Im
Published: October 2014

This study investigated whether the allophonic contrast in the second language (L2) may require contact with the lexicon to influence the perception. Given that English medial voiceless stops occur with aspiration in stressed, but without aspiration in unstressed syllables, Korean learners of English were tested for aspirated and unaspirated allophones of /p/ for perceptual preference in appropriate and inappropriate stress contexts in the second syllable of disyllabic words. The stimuli included four types of non-words and eight pairs of real words (four pairs each for high-frequency and low-frequency words), and participants were asked to judge the perceptual preference of each token on a 7-scale (1 = a bad example, 7 = a good example). The results demonstrated that in tests with non-words, there was no significant difference in the ratings as a function of context appropriateness (e.g., [ípɚ] vs. [íphɚ]), with higher rankings for initially-stressed words. By contrast, in real words, participants preferred the correct allophones (e.g., [képɚ] vs. [képhɚ] “caper”). The frequency of real words further showed a significant effect. This finding suggests that allophony in L2 is driven by lexicality (Whalen et al., 1997). Exemplar theory (Pierrehumbert 2001, 2002) provides a more effective means of modeling this finding than do traditional approaches.
Language mode effects on second language categorical perception
Authors: Lopez Prego Beatriz , Jongman Allard
Published: October 2014

This study investigates the perception of the /b/-/p/ voicing contrast in English and Spanish by native English listeners, native Spanish listeners, and highly proficient Spanish-speaking second-language (L2) learners of English with a late onset of acquisition (mean = 10.8) and at least three-year residence in an English-speaking environment. Participants completed a forced-choice identification task where they identified target syllables in a Voice Onset Time (VOT) continuum as "pi" or "bi." They listened to 10 blocks of 19 equidistant steps ranging from + 88 ms-VOT to -89 ms-VOT. Between blocks, subjects read and wrote responses to language background questions, thus actively processing the target language. Monolinguals completed the task in their native language (L1). L2 learners completed the task once in their L1 and once in their L2, thus providing a manipulation of "language mode" (Grosjean, 2001). The results showed that L2 learners’ category boundary in English did not differ from that of monolingual English listeners, but their category boundary in Spanish differed from that of monolingual Spanish listeners and from their own category boundary in English. These results suggest that the language mode manipulation was successful and that L2 learners can develop new phonetic categories, but this may have an impact on their L1 categories.
Does second language experience modulate perception of tones in a third language?
Authors: Qin Zhen , Jongman Allard
Published: October 2014

Previous studies have shown that English speakers pay attention to pitch height rather than direction, whereas Mandarin speakers are more sensitive to pitch direction than height in perception of lexical tones. The present study addresses if a second language (L2, i.e., Mandarin) overrides the influence of a native language (L1, i.e., English) in modulating listeners' use of pitch cues in the perception of tones in a third language (L3, i.e., Cantonese). English-speaking L2 learners (L2ers) of Mandarin constituted the target group. Mandarin speakers and English speakers without knowledge of Mandarin were included as control groups. In Experiment 1, all groups, naïve to Cantonese tones, discriminated Cantonese tones by distinguishing either a contour tone from a level tone (pitch direction pair) or a level tone from another level tone (pitch height pair). The results showed that L2ers patterned differently from both control groups with regard to pitch cues under the influence of L2 experience. The acoustics of the tones also affected all listeners' discrimination. In Experiment 2, L2ers were instructed to identify Mandarin tones to measure their sensitivity to L2 tones. The results showed that L2ers' sensitivity to L2 tones is not necessarily correlated with their perception of L3 tones.
Does early foreign language learning in school affect phonemic discrimination in adulthood?
Authors: Harada Tetsuo
Published: October 2014

Long-term effects of early foreign language learning with a few hours’ classroom contact per week on speech perception are controversial: some studies show age effects of minimal English input in childhood on phonemic perception in adulthood, but others don’t (e.g., Lin et al., 2004). This study investigated effects of a younger starting age in a situation of minimal exposure on perception of English consonants under noise conditions. The listeners were two groups of Japanese university students: early learners (n = 21) who started studying English in kindergarten or elementary school, and late learners (n = 24) who began to study in junior high school. The selected target phonemes were word-medial approximants (/l, r/). Each nonword (i.e., ala, ara), produced by six native talkers, was combined with speech babble at the signal-to-noise ratios (SNRs) of 8 dB (medium noise) and 0 dB (quite high noise for L2 listeners). A discrimination test was given in the ABX format. Results showed that the late learners discriminated /l/ and /r/ better than the early learners regardless of the noise conditions and talker differences (p < 0.05). A multiple regression analysis revealed that length of learning and English use could contribute to their discrimination ability.
The identification of American English vowels by native speakers of Japanese before three nasal consonants
Authors: Nozawa Takeshi
Published: October 2014

Native speakers of Japanese identified American English vowels that are uttered before three nasal consonants /m, n, ŋ/ and three oral stop consonants /b, d, ɡ/. Of the seven vowels /i, ɪ, eɪ, ɛ, æ, ɑ, ʌ/, /æ/ was generally less accurately identified before nasal consonants than before oral stop consonants, and this tendency was stronger when /ŋ/ follows. This tendency is probably attributed to the extended raising of /æ/ before /ŋ/ and the Japanese listeners’ limited sensitivity to differentiate three nasal phonemes in coda position. /ɪ/, on the other hand, was identified more correctly before /ŋ/ than before the other two nasal consonants, also probably because the vowel is raised before /ŋ/. This vowel was more often misidentified as /ɛ/ before /m/ and /n/. /ɑ/ and /ʌ/ were less accurately identified before stop consonants, but after nasal consonants, /ʌ/ was more often misidentified as /ɑ/. /ɑ/ and /ʌ/ may sound alike to Japanese listeners in every context, but before nasal contexts, both of these vowels may sound closer to the Japanese vowel /o/. The results generally revealed that identification accuracy cannot be solely accounted for in terms of the place of articulation of the following consonant.
A preliminary investigation of the effect of dialect on the perception of Korean sibilant fricatives
Authors: Holliday Jeffrey J. , Lee Hyunjung
Published: October 2014

Korean has two sibilant fricatives, /sh/ and /s*/, that are phonologically contrastive in the Seoul dialect but are widely believed to be phonetically neutralized in the Gyeongsang dialects spoken in southeastern South Korea, with both fricatives being acoustically realized as [sh]. The current study investigated the degree to which the perception of these fricatives by Seoul listeners is affected by knowledge of the speaker’s dialect. In the first task, the stimuli were two fricative-initial minimal pairs (i.e., four words) produced by 20 speakers each from Seoul and Gyeongsang. Half of the 18 listeners were told that the speakers were from Seoul, and the other half were told they were from Gyeongsang. Listeners identified the 160 word-initial fricatives and provided a goodness rating for each. It was found that neither the speaker’s actual dialect nor the primed dialect had a significant effect on either identification accuracy or listeners’ goodness ratings. In a second task, listeners identified tokens from a seven-step continuum from [sada] to [s*ada]. It was found that listeners who were primed for Gyeongsang dialect were more likely to perceive tokens as /s*/ than listeners primed for Seoul, which may reflect a dialect-based hypercorrective perceptual bias.
Language is not destiny: Task-specific factors, and not just native language perceptual biases, influence foreign sound categorization strategies
Authors: Schertz Jessamyn L. , Lotto Andrew
Published: October 2014

Listeners were trained to distinguish two novel classes of speech sounds differing in both Voice Onset Time (VOT) and fundamental frequency at vowel onset (f0). One group was shown Korean orthography during the training period (“symbols” group) and the other English orthography (“letters” group). During a subsequent test phase, listeners classified sounds with mismatched VOT and f0. The two groups relied on different cues to categorize the contrast: those exposed to symbols used f0, while those exposed to letters used VOT. A second experiment employed the same paradigm, but the two dimensions defining the contrast were closure duration (instead of f0) and VOT. In this more difficult experiment, successful listeners in the “letters” group again classified the hybrid stimuli based on VOT, while the single listener in the “symbols” group who passed the learning criterion used closure duration. In both experiments, subjects showed different categorization patterns based on orthography used in the presentation, even though orthography was irrelevant for the experimental task. Listeners relied on VOT when the stimuli were presented with English, but not foreign, orthography, showing that task-related information (as opposed to native language biases alone) can direct attention to different acoustic cues in foreign contrast classification.