bluuebunny/crossref_metadata_2025 huggingface dataset:
Recognition of reduced speech and use of phonetic context in listeners with age-related hearing impairment.
Authors: Janse Esther , Ernestus Mirjam
Published: October 2013

This study investigated identification of reduced words (e.g., “onry” for “ordinary”) by young listeners, elderly listeners, and young listeners in whom we simulated a hearing impairment. The main question was whether elderly listeners benefit as much as young listeners from phonetic context in recovering reduced words and whether any context difference should be attributed to hearing loss or cognitive decline. Participants were presented with excerpts from a corpus of spontaneous Dutch, consisting of either the target word in isolation or in its sentential context. The sentence context was not highly semantically/syntactically constraining. As expected, elderly listeners and young listeners with a simulated hearing impairment showed lower accuracy scores than the normal-hearing young adults. More importantly, the two hearing-impaired listener groups benefited less from context than the normal-hearing young group. Within the elderly group, hearing sensitivity also predicted one’s amount of context benefit. Additionally, hearing sensitivity and age, but not a cognitive processing measure, predicted overall identification performance among the elderly listeners. In conclusion, our results suggest a double handicap for both young and old hearing-impaired listeners: they have more difficulty interpreting the acoustic signals of reduced words, and also benefit less from phonetic cues contained in surrounding words.
Consonant identification for hearing impaired listeners.
Authors: Li Feipeng , Allen Jont
Published: October 2013

This research investigates the impact of sensorineural hearing loss on consonant identification. Two elderly subjects, AS with a moderate to severe sloping hearing loss and DC with a severe sloping high-frequency hearing loss, volunteered for the pilot study. Speech perception test reveals that AS has no problem with /ta/, and has little difficulty with /pa, sa, da, za/, but never reports /ka/ and /ga/ due to a cochlear dead region from 2–3.5 kHz in the left ear, which blocks the perceptual cues for /ka/ and /ga/. In contrast, her right ear hears these sounds. Although NAL-R improves the average perception score from 0.42 to 0.53 under quiet conditions, it provides little help for noisy speech (a 3% increase at 12 dB signal to noise ratio); /ka/ and /ga/ remain unintelligible with NAL-R. The other subject DC can hear all the 16 consonants tested in both ears with the assistance of NAL-R. However, it only improves the recognition scores of low and midfrequency sounds such as /pa, ba/ and /ka, ga/. It degrades the high-frequency sounds such as /ta/ and /da/. No cochlear dead region is confirmed for DC.
Discrimination of blasting sounds, music, and wind noise using a Gaussian mixture-model classifier.
Authors: Wilson D. Keith , White Michael J.
Published: October 2013

Wind noise and acoustic signals were recorded outdoors with a horizontally oriented, square, 7×7 microphone array having an intersensor spacing of 0.914 m. Even with this very small spacing, the wind noise was found to have very little spatial correlation at frequencies above 15 Hz, thus indicating that the turbulent eddies responsible for the wind noise distort very rapidly. This property can be used to distinguish wind noise from acoustic signals possessing similar frequency content. To demonstrate this idea, wavelet processing was applied to recordings with predominantly wind noise, propane cannon blasts, and unsteady but persistent sounds (music). A set of features involving ratios of the wavelet coefficients at different frequencies and between different microphones was then formulated. Three of the features relate to the time-domain shape of the signals, two to the spectral content, and three to the spatial correlation. A Gaussian-mixture-model classifier was trained with the feature statistics of the three signal types, and classifier predictions were then compared against an independent test data set. Results indicate a 96.6% correct classification rate of the signals. Signal shape features reliably distinguish the blasting and music, whereas the coherence features reliably distinguish the wind noise from acoustic signals.
Auditory stream segregation in six-month-old infants and adults.
Authors: Smith Nicholas A. , Trainor Laurel J.
Published: October 2013

Auditory stream segregation in six-month-old infants was examined in a paradigm adapted from Bregman and Rudnicky (1975). In a conditioned head-turn procedure, listeners' detection of changes in the temporal order of 2200 and 2400 Hz target tones was tested under three conditions. For developmental comparison, as well as validation of the stimulus design, adults were tested in an identical procedure. Adults clearly detected changes in the order of the target tones when presented alone, but performance suffered when the target tones were preceded and followed by 1460 Hz flanker tones. However, performance improved when the flanker tones were embedded within a series of additional 1460 Hz tones, which captured the flanker tones into an isochronous stream of tones, perceptually segregated from the targets. Although infants performed worse than adults under the same conditions, infants also benefited from the addition of captor tones, suggesting that they too can use grouping cues to organize and attend to elements in the auditory scene.
Extension of the iterative nonlinear contrast source method to nonlinear media exhibiting tissue-like attenuation.
Authors: Verweij Martin , Huijssen Jacob , de Jong Nico
Published: October 2013

Recently, the Iterative Nonlinear Contrast Source (INCS) method has been developed to compute the pulsed acoustic pressure field in a nonlinear and lossless medium that extends over a very large, 3-D domain. This method solves the nonlinear wave equation by considering the nonlinear term as a distributed contrast source in a linear background medium. The full nonlinear wave field follows by convolving the background Green’s function with successive estimates of the contrast source. It has been shown that by spatiotemporal filtering of the convolution factors, the method yields accurate field predictions even for a discretization approaching two points per smallest wavelength or period. The current paper discusses how attenuation, in particular tissue-like power law losses, may be incorporated into the method through the introduction of a causal compressibility relaxation function. The latter gives the background the desired loss behavior. Fields in nonlinear media with different power law losses are presented, as computed by the extended INCS method. Moreover, the ability of both the lossless and the extended INCS method to evaluate fields at the shock formation distance is shown. Especially the latter results show the significance of using a proper, tissue-like power law. [Work supported by STW and NCF.]
Measurement and modeling of solid cylinders near interfaces.
Authors: Williams Kevin , Lopes Joe , Thorsos Eric , Marston Philip
Published: October 2013

Acoustic scattering from solid cylinders located near interfaces include effects due to energy interacting with those interfaces. Therefore, modeling cylinder response also requires models of scattering from and penetration across those interfaces. The simplest modeling can be carried out using a plane wave approximation. Using this approximation finite element results for a solid cylinder in the freefield are used to calculate the acoustic scattering of the same cylinder located near an interface. These calculations are compared to experimental data for cylinder target strength and possible reasons for differences seen are discussed. The physical mechanisms responsible for the cylinder’s response are examined and cylinder surface displacements are shown. [Work supported by the Office of Naval Research and the Strategic Environmental Research and Development Program.]
Modeling weak shocks produced by high-intensity focused ultrasound.
Authors: Khokhlova Vera A. , Bessonova Olga V. , Canney Michael S. , Bailey Michael R. , Soneson Joshua E. , Crum Lawrence A.
Published: October 2013

Shock waves of up to 100 MPa may form at the focus of high-intensity focused ultrasound (HIFU) transducers at clinically reported in situ intensities of up to 30,000 W/cm2. The heating due to shocks is sufficient to boil tissue in milliseconds, which dramatically alters the treatment. Quantification of enhanced heating from shocks is therefore critical to treatment planning. In this work, several approaches and temporal grids of different resolutions were used to simulate HIFU fields. Peak positive pressure, which determines the shock amplitude, and thus the heating rate were found to be the most sensitive to the parameters of the numerical scheme. Heating rates calculated in modeling and estimated using weak shock theory from the measured and modeled waveforms were compared. Time to boil measured in tissue phantoms and tissue was used as a metric of the heating efficiency of shocks. It is shown that the bandwidth limitations in the waveform measurements result in underestimation of the heat rates, although boiling onset predicted in modeling agreed well with the experimental data. An experimentally validated numerical model thus can be an effective tool in both laboratory and clinical HIFU setting. [Work is supported by NIH EB007643 and NSBRI SMST01601.]
Sensitivity to interaural level differences in high-rate high-frequency click trains: A functional magnetic resonance imaging assessment.
Authors: Stecker G. Christopher , McLaughlin Susan A.
Published: October 2013

While the auditory cortex (AC) is known to be necessary for accurate sound localization, the nature of spatial representation in AC remains poorly understood. Past animal studies have quantified sensitivity to auditory spatial cues [e.g., interaural level difference (ILD)] across subregions of AC. In this study, functional magnetic resonance imaging (fMRI) was used to assess ILD sensitivity across the surface of human AC. Normal-hearing listeners were presented with narrowband Gabor click trains (4000 Hz center frequency, 3 ms interclick interval) that varied parametrically in ILD over a range of +/− 30 dB. Simultaneously, whole-head fMRI images were acquired using a sparse imaging paradigm at 3 Tesla (32-slice EPI, 3.0×3.0×4.5 mm resolution, TR=12 s). During imaging, listeners detected rare target changes in ICI. Hemodynamic responses of compact AC subregions in individual subjects were assessed quantitatively using statistical pattern recognition with two goals: (1) to identify contiguous AC regions that share common patterns of sensitivity to ILD, and (2) to quantify, in information-theoretic terms, the ability of those responses to differentiate stimuli differing in ILD.
End-state comfort governs kinematic variation in English flap/tap sequences.
Authors: Derrick Donald , Gick Bryan
Published: October 2013

Derrick & Gick [Can. Acoust. 36(3), 162 (2008)] found that North American English flap/tap singletons are produced using up to four phonetically conditioned kinematic variants (up-flaps, down-flaps, postalveolar taps, and alveolar taps), dependent on the position of the tongue tip in neighboring rhotic and nonrhotic vowels. Our pilot work has shown that sequences of multiple flap/tap variants are highly mechanically interdependent (e.g., subjects never produce two up-flaps or two down-flaps in adjacent syllables). The present study tests flap/tap sequences for compliance with “end-state comfort” [Rosenbaum et al., Acta Psychologica 94, 59 (1996)], as evidence for look-ahead planning. Twelve subjects’ tongue positions were measured during production of English words and word pairs with one- and two-flap sequences. Results show that sequences of flaps end with a preferred tongue tip position. For example, for 11 subjects, the /d/ of “edit” is realized as an alveolar tap or down-flap in “edit the,” but an up-flap in “edit a,” both facilitating ending the sequence with a low tongue position. A general avoidance of a sequence-final up-flap was also observed, such that /d/ of “edify” is an alveolar-tap or down-flap, while, for eight subjects, “editor” shows an up-flap, postalevolar tap sequence. [Work supported by NSERC.]
Comparing the effects of internal waves, mode coupling, and change in bandwidth of a radiated signal on low mode energy propagation.
Authors: Grigorieva Natalie , Fridman Gregory , Mercer James , Andrew Rex , Wolfson Michael , Howe Bruce , Colosi John
Published: October 2013

Wideband signal propagation modeling is carried out for the actual space-time configuration realized during the long-range ocean acoustic propagation experiment (LOAPEX) conducted in the North Pacific in 2004. In particular, the experiment used the Kauai transmit station that was located at a range of 2432 km from a vertical line array (VLA), M-sequence at 75 Hz, and a source depth of 800 m close to the depth of a sound-channel axis. Two sound speed profiles were utilized to get the smooth two-dimensional sound speed field. The first one was the profile obtained from the conductivity-temperature-depth (CTD) measurements at the Kauai station. The second sound speed profile from the VLA location was based on a CTD cast taken at station T50 (50 km from the VLA). To take into account the acoustic fluctuations due to internal waves, the buoyancy frequency profile based on LOAPEX CTD measurements made at station T50 was used. For simulations, 512 values of the horizontal wave number were utilized with the maximal mode number equal to 50. The low modes intensity received by the hydrophones close to the sound channel axis at the VLA is compared with the results of simulations. [Work supported by ONR and ONR Global.]
The perception of intermediate phonological relationships.
Authors: Hall Kathleen Currie
Published: October 2013

It has been shown that pairs of segments that are allophonic in a language are perceived as being more similar than pairs that are contrastive in a language [Boomershine et al., (2008)]. There is also evidence that neutralized contrasts in a language are perceived as more similar than non-neutralized contrasts [Hume and Johnson (2003)]. Third, there is evidence that phonological relationships should be defined along a continuum of predictability, rather than as a categorical distinction between “allophonic” and “contrastive” [Hall (2008)]. In combination, these facts predict that pairs of segments that fall along a cline of predictability of distribution should also fall along a cline of perceived similarity. This paper presents results of a perception experiment that tests this prediction by examining the perceived similarity of four pairs of sounds in German: (1) [t]-[t∫], which is almost fully contrastive (unpredictably distributed); (2) [t]-[d] and (3) [s]-[∫], which are each partially contrastive (partially predictably distributed); and (4) [x]-[ç], which is almost fully allophonic (completely predictably distributed). If the notion of a cline of predictability is correct, these four pairs will align themselves along a cline of similarity with [t]-[t∫] being rated as the most distinct and [x]-[ç] as the most similar.
Extending the trade-off between spatial resolution and variance in quantitative ultrasonic backscattering imaging (QUS) using full angular spatial compounding.
Authors: Lavarello Roberto J. , Sanchez Jose R. , Oelze Michael L.
Published: October 2013

Tissue microstructure properties can be estimated using backscattered power measurements and quantitative ultrasound (QUS) techniques. The objective of this study was to evaluate the use of full angular (i.e., 360°) spatial compounding as a means of extending the trade-off between QUS variance and spatial resolution. Simulations and experimental results were conducted with a 10 MHz, f/4 transducer. In simulations, a synthetic phantom consisting of two eccentric cylindrical regions with Gaussian inclusions with 50 and 25 μm average scatterer diameter (ASD) values was analyzed. The use of multiple view data reduced the corresponding ASD standard deviations from 13.7 and 19.6 μm to 2.5 and 3.7 μm, respectively. In experimental measurements, a phantom that contained glass spheres with diameters between 45 and 53 μm was evaluated. The ASD standard deviation obtained using single view data was 10.4 μm. When using 32 angles of view and reducing both region-of-interest (ROI) dimensions by a factor of 2, the ASD standard deviation was reduced to 4.8 μm. The results presented here demonstrate that both QUS spatial resolution and precision can be improved simultaneously by using full angular spatial compounding. This method finds direct applicability for breast tissue characterization, for which full angular coverage is available.
Investigation of the spatial and temporal characteristics of the New Zealand seismic noise field.
Authors: Brooks Laura A. , Townend John , Behr Yannik , Gerstoft Peter , Bannister Stephen
Published: October 2013

The use of microseismic interferometry methods to construct tomographic models requires an understanding of the spatio-temporal characteristics of the noise field, particularly in regions such as New Zealand, where multiple potential sources exist. Directional variations in noise levels compatible with large-scale differences in sea state have previously been reported (Lin et al., Geophys. J. Int., 2007). The aims of the current study are to further quantify spatial and seasonal variations in the seismic noise field in conjunction with an oceanic wave state model. This involves the analysis of a larger dataset over a longer time period, and requires more sophisticated noise-field analysis. A preliminary comparison of New Zealand and environments in which the azimuthal distribution of seismic noise sources has been investigated using beamforming is presented. The applicability of beamforming to New Zealand conditions is then discussed in the context of regional ambient noise models. Methods by which estimates of the seismic noise field’s spatio-temporal characteristics can be related to contemporaneous ocean wave climate observations are also highlighted.
An in-situ diffusivity measurement method for diffuser design in concert halls.
Authors: Jeon Jin Yong , Kim Yong Hee
Published: October 2013

This study investigates an in-situ measurement method to evaluate the diffuseness of a sound field using scale model concert halls. The diffusers were applied to scale model concert halls in which the impulse responses at both the audience and stage area were observed. Both reflection number (RN) and reflection energy (RE) were used as in-situ diffusivity indices: RN is defined by the number of reflection rays of which critical amplitude level is within −30 dB after the direct sound, and RE defined by the integrated energy at the normalized impulse responses. Through the scale model measurements, it was observed that half of the side walls near the stage were effective for diffuseness of sounds both in auditorium and on stage. It was also found that the balancing of in-situ diffusivity is useful for diffuseness perception, which is subject to the level of the direct sounds.
Detection and classification of typhoons using underwater acoustic sensors in the western Pacific Ocean.
Authors: Ma Barry , Yang Y. J.
Published: October 2013

About two years of underwater ambient noise were collected using Passive Aquatic Listeners (PALs) in the western Pacific Ocean. PALs were deployed using the bottom-mount or surface-mount buoys on the possible typhoon paths. Several episodes of intensive typhoon noise were recorded during the passage of these powerful tropical storms. These acoustic data are compared with other ancillary data for the classification of typhoons. Using the underwater ambient noise to classify the intensity of typhoons is a relatively reliable method. The instrument is placed away from the air-sea interface in a less destructible environment and provides relative in situ measurement of the wind speed. The ambient noise recordings from the deployment also include the biology, shipping, and other surface noises, but the noises from the typhoons are the most distinguishable against all other sources of noise. The noise budgets from different deployment sites are also presented.
Effects of visual cues and phonetic contexts in perception of non-native contrasts by Cantonese learners of english.
Authors: Li Bin
Published: October 2013

Visual articulatory information, in addition to audio features, is integrated in L1 and L2 speech perception automatically and unconsciously [McGurk and MacDonald (1976); Rosenblum et al. (1997); Hardison (2003); Hazan et al. (2005)]. Previous literature on consonant perception has reported that visual aid is most significant with places of articulation, and that with manners, except with /r/ and /l/, has received little attention due to lack of research significance. Contrary to the commonly held idea, however, that the articulation of [l] and [n] is visually similar, our examination on video recording of three native English speakers’ production of words contrasting [l] and [n] syllable initially suggests visual differences in advancement of tongue tips. This study investigates effects of such visual information in the identification of the non-native contrast by Cantonese learners of English. Results show that the relatively more distinct visual information can only help Cantonese speakers better perceive the two sounds in certain contexts, and in others cause more confusion.
Coupling of midaudio frequency thermoacoustic prime movers.
Authors: McDonald Brenna G. , Symko Orest G.
Published: October 2013

Multiple unit midaudio frequency thermoacoustic engine arrays have been studied in terms of synchronized self-sustaining oscillators. Thermoacoustic engines can be acoustically coupled through shared gas when attached to a common cavity. The coupling between devices was studied by varying the cavity volume, and by varying the separation distance between devices in an array. Frequency and phase measurements for two-engine arrays have suggested that the engines entrain at a common frequency with approximately zero phase difference implying the onset of synchronization. Amplitude measurements of synchronized arrays suggest that the acoustic amplitude is equal to the sum of the amplitudes of each uncoupled engine, and agree with predictions. Synchronization of four or more units in an array implies that the coupling between engines is global and depends on the volume of the cavity and the density of the gas within the cavity. The detuning between two engines was increased until synchronization no longer occurred. The threshold for this was found to be for a frequency difference of between 80 and 98 Hz for the given coupling strength when operating near 2.5 kHz. [Research supported by the U.S. Army Space and Missile Defense Command/U.S. Army Forces Strategic Command.]
Weak shock propagation in the ocean and marine sediments.
Authors: McDonald B. Edward
Published: October 2013

The nonlinear progressive wave equation (NPE) [B. E. McDonald and W. A. Kuperman, JASA 81, 1406 (1987)] was initially developed to model weak shock waves in a refracting medium (specifically, ocean acoustic convergence zones). It has been refined to include high-angle and two-way propagation. Inclusion of two-way propagation improves agreement with empirical power laws for peak pressure from an explosive as a function of range and explosive charge. The NPE is currently being used to examine weak shock propagation into marine sediments for studies related to mine countermeasures. An intriguing behavior results from the stress-strain relation for Hertzian granular media, in which stress is proportional to the 3/2 power of strain rate. Numerical and analytic solutions with the Hertzian nonlinearity reveal its most nonlinear behavior (shock formation) near zero stress, whereas in a fluid, shock formation results from high stress. Numerical experiments are presented to determine whether shocks resulting from Hertzian nonlinearity can be observed with nominal values of frequency-linear attenuation common to granular media. [Work supported by the Office of Naval Research.]
Modeling of acoustic scattering by sphere on a planar seabed.
Authors: Cao Zhengliang , Du Shuanping , Zhou Shihong , Wang Fangyong
Published: October 2013

A model of acoustic scattering from spherical target above a planar seabed is advanced to a condition of irradiation by a point source, with both of T matrix method and complex images method. Compared to the other model [J. A. Fawcett and R. Lim, J. Acoust. Soc. Am. 114, 1406–1415 (2003)], this model could be used to calculate scattering field from target above a planar interface in three dimension space or by bounded source beam. Comparing some coefficients by complex images method with that by analytical formula or numerical quadrature, the computing method of the model is examined to be efficient and accurate. In addition, numerical examples of a rigid sphere and an elastic spherical shell are compared for scattering field from the target on a fluid seabed, and the scattering field dependent angle is investigated from the different of grazing angle of incident wave. [Work supported by the National Natural Science Foundation of China (Grant No. 10704068).]
Modeling the low- to mid-frequency scattering from a proud cylinder: Boundary and near-field effects.
Authors: Zampolli Mario , Williams Kevin L.
Published: October 2013

A 2:1 aspect ratio solid aluminum cylinder is placed on the planar interface between two fluids (water/sand and water/air), with a point source radiating at frequencies for which the acoustic wavelengths range from 0.5 to 12 cylinder lengths. The distance between the source and the target is approximately 100 wavelengths, relative to the center frequency, and a vertical receive array is placed near the source. The problem is studied using a finite-element target scattering model, which is capable of treating axially symmetric objects via the decomposition of the unknowns into a Fourier basis around the axis of symmetry. Since the axis of the cylinder is parallel to the planar interface, the overall problem is not axially symmetric. Nevertheless, an approximate solution is obtained, which takes into account the interface reflection of the incident field, as well as the first bounce of the scattered field (via the Helmholtz–Kirchhoff integral with layered medium Greens functions). Small variations in the source and receiver positions cause large changes in the received signal, which can be explained by a Lloyd mirror-like interference resulting from the coherent addition of the point-sources and image point-sources with which the incident field and the scattered field can be described.
Using moored passive acoustic recorders to assess seasonal occurrence and movements of southern resident killer whales in the coastal waters of Washington State.
Authors: Hanson M. Bradley , Emmons Candice K. , Nystuen Jeffrey A. , Lammers Marc O.
Published: October 2013

Designating critical habitat is mandated for species listed under the U.S. Endangered Species Act. This task has only been partly accomplished for southern resident killer whales (SRKWs) because winter distribution is poorly understood due to a variety of factors limiting visual sightings within their known central California to northern British Columbia range. To capitalize on the unique vocal behavior of resident killer whales, including pod-specific dialects, two types of acoustic recorders were deployed at strategic locations that span the Washington coast. Between 2005 and 2008 recorders were deployed in early winter for an average of 175.5 days at up to four sites. These functioned for an average of 114.8 days and collected a total of 47 SRKW detections. This exceeds the number of visual sightings during the same time period (15). Additionally, northern resident, transient, and offshore killer whales were recorded as well as Pacific white-sided dolphins, and humpback and sperm whales. SRKW were detected by both types of recorders and in all areas. Detections were made between Jan. and July with the majority of these detections in Mar., Apr., and May. This new information will be of key importance to managers in meeting recovery goals.
Wideband fast multipole accelerated boundary element methods for the three-dimensional Helmholtz equation.
Authors: Gumerov Nail A. , Duraiswami Ramani
Published: October 2013

The development of a fast multipole method (FMM) accelerated iterative solution of the boundary element method (BEM) for the Helmholtz equations in three dimensions is described. The FMM for the Helmholtz equation is significantly different for problems with low and high kD, where k is the wave number and D the domain size, and for large problems, the method must be switched between levels of the hierarchy. The BEM requires several approximate computations: numerical quadrature and approximations of the boundary shapes using elements. These errors must be balanced against approximations introduced by the FMM and the convergence criterion for an iterative solution. These different errors must all be chosen in a way that, on the one hand, excess work is not done and, on the other, that the error achieved by the overall computation is acceptable. Details of translation operators for low and high kD choice of representations and BEM quadrature schemes, all consistent with these approximations, are described. A novel preconditioner using a low accuracy FMM accelerated solver as a right preconditioner is also described. Results of the developed solvers for large boundary value problems with 0.0001⩽kD⩽500 are presented and shown to perform close to theoretical expectations.
Resolving spatial seabed variability by Bayesian inference of seabed reflection inversions.
Authors: Dettmer Jan , Dosso Stan E. , Holland Charles W.
Published: October 2013

This paper considers Bayesian inversion of seabed reflection-coefficient data for multilayer geoacoustic models at several sites with the goal of studying spatial variability of the seabed. Rigorous uncertainty estimation is of key importance to resolve spatial variability between measurement sites from the inherent inversion uncertainties. Geoacoustic uncertainty estimation is carried out including Bayesian model selection and comprehensive estimation of data error statistics. Model selection is addressed using the Bayesian information criterion to ensure parsimony of the parametrizations. Data error statistics are quantified by estimating full covariance matrices from data residuals, and a posteriori statistical validation is carried out. A Metropolis-Hastings sampling algorithm is used to compute posterior probability densities. Five experimental sites are considered along a track located on the Malta Plateau, Mediterranean Sea, and the inversion results are compared to cores and subbottom profiler sections. Differences between sites that exceed the estimated geoacoustic uncertainties are interpreted as spatial variability of the seabed.
Ralph Goodman, builder of laboratories.
Authors: Marshall Samuel W.
Published: October 2013

Ralph had an extraordinarily successful career in building programs and laboratories. He started with an overall vision of what was to be built while determining the principle obstructions. He carefully avoided early details which would most often be overtaken by events. In addition, he was an eminent scientist whose acumen in a number of technical areas permitted him breadth of very constructive technical leadership. Besides a history of how Ralph got into underwater acoustics and his first major position in management, some personal anecdotes will be presented to emphasize how he successfully dealt with people and with some very difficult situations in this and subsequent undertakings.
Particle filter source tracking in a changing geoacoustic environment.
Authors: Yardim Caglar , Gerstoft Peter , Hodgkiss, William S.
Published: October 2013

This paper addresses the problem of tracking the acoustic source parameters such as the depth, range, and speed in evolving geoacoustic environments. It is well known that inaccurate knowledge about the environmental parameters such as the sound speed profile (SSP), water depth, sediment, and bottom parameters may result in significant errors in source parameters. To counter this, a particle filtering (PF) approach is adopted here where the geoacoustic parameters are tracked together with the source location and speed in a range-dependent environment. This allows accurate, real-time updating of the environment the ship is moving in and hence source can be located at any time accurately. As a sequential Monte Carlo technique that can operate on nonlinear systems with non-Gaussian probability densities, the PF is an ideal tracking algorithm to perform tracking of source and environmental parameters and their evolving probability distributions. The algorithm is tested on a sloping environment with the SSP, water depth, and sediment parameters evolving as the ship moves. The change in the water depth created the well-known “source mirage effect,” but the PF was still able to track the true source, geoacoustic parameters, and their evolving densities in this spatially varying environment. [Work supported by ONR.]
Perception-production relationship in French vowel learning in adulthood.
Authors: Levy Erika S. , Law Franzo
Published: October 2013

The present study examined the extent to which perceptual performance by American English (AE) individuals predicted their accuracy in producing second-language (L2) Parisian French (PF) vowels. Three groups of AE participants (no, moderate, and extensive French-language experience) participated in two perceptual tasks (categorial discrimination and perceptual assimilation), and a production (repetition) task involving PF /y-œ-i-a-u/ in bilabial /rabVpa/ and alveolar /radVta/ contexts within a phrase. Results from perception tasks correctly predicted overall production difficulties and effects of language experience and consonantal context in L2 production. Paralleling their perceptual patterns, front rounded vowel productions by AE participants were mislabeled more often as back rounded vowels than as front vowels by native-French speakers. PF /œ/ was produced more accurately with greater L2 experience. Production accuracy of /y/ was also greater with extensive experience, a finding not expected based on minimal language-experience effects on /y/ perception. Productions of PF /u/ were identified approximately twice as accurately in bilabial context as in alveolar, in a pattern consistent with discrimination performance. Thus, PF /u/ may be considered a “similar” vowel in alveolar context, but not in bilabial, suggesting an allophonic level of representation in L2 learning, both in perception and production.
Sound localization acuity in the cat: Integrating data from psychophysical, physiological, and acoustical cue studies.
Authors: Tollin Daniel J
Published: October 2013

The minimum audible angle (MAA), a psychophysical measure of auditory spatial acuity, is the smallest angle separating the locations of two sound sources, presented sequentially, that can be reliably discriminated. In humans and cats, the MAA for tone stimuli depends jointly on source azimuth and tone frequency. It is hypothesized that this results from the spatial and frequency dependence of the acoustical cues to location. Thus, for high-frequency (>1.5 kHz) stimuli, where the predominant cue for source azimuth is the interaural level difference (ILD), the MAA would be determined by the spatial and frequency dependence of the ILD cue. However, for this to be true, the underlying neural acuity for ILD cues must be frequency independent. Here the hypothesis was tested that the frequency dependence of the psychophysical MAA in cats can be explained by the frequency dependence of the ILD cue with source azimuth and the frequency independence of the acuity of neurons (or neural MAA) in the lateral superior olive (LSO) to ILDs. The LSO is a brainstem structure responsible for the initial encoding ILDs. The data from acoustical cue measurements and physiological and psychophysical studies in cats support this hypothesis. [Work supported by NIH Grants Nos. DC006865 and DC02840.]
Three-dimensional numerical simulation of sonic boom diffraction around buildings using a dispersion-relation-preserving scheme.
Authors: Cho Sang I. , Sparrow Victor W.
Published: October 2013

A finite difference time domain approach is used to model the temporally and spatially dependent pressure loading on a rigid structure due to an incident low-amplitude N-wave sonic boom. Analytically, one expects strong diffraction due to building corners and pressure doubling near rigid walls. The three-dimensional linear wave equation is sufficient to model the interaction between the structure and the low-amplitude sonic boom at the ground level. Applying a fourth-order dispersion-relation-preserving scheme and a four-level explicit time marching scheme, an excellent dispersion characteristic is achieved without sacrificing computational efficiency of the algorithm. NASA flight testing at Edwards, CA during the summer of 2006 is numerically simulated by matching the geometries of the simulated structure to the actual residential house used for the flight test and using the waveform of a recorded boom as the incoming wave for the simulation. A direct comparison to the experimental data allows the quantitative validation of the simulation results. The feasibility of using this model for calculation of the pressure loads on other structures can be determined based on the accuracy of this numerical solution. [Work supported by NASA. The authors appreciate NASA making the 2006 and 2007 flight data available for this work.]
Innovations detector for buried ojects.
Authors: Sullivan Edmund J. , Xiang Ning , Candy James V.
Published: October 2013

The acoustic detection of buried objects is hampered by the fact that, at frequencies high enough to resolve the object, the ground is a poor conductor of the acoustic probe signal. In order to circumvent this problem, techniques have been developed whereby high-level low frequency probe signals are used to excite resonances in the object, which, in turn, cause microscopic displacement of the ground surface that can be sensed with a laser Doppler vibrometer (LDV). Although this approach shows great promise, it is limited by speckle noise. This is a form of noise arising from the coherent property of the laser signal. In this paper we demonstrate real data results using an innovations detector, which operates by sensing the change in the statistics of the returned laser backscatter signal when a target is present. When there is no target present, the signal can be modeled by a Kalman filter, such that its innovation sequence is zero mean and white. Any deviation of the signal from this model then disrupts the innovation sequence, causing a weighted sum squared residual test to indicate the presence of a signal. Real data results are shown.
Helmholtz-like resonators for thermoacoustic prime movers.
Authors: Andersen Bonnie J. , Symko Orest G.
Published: October 2013

In a thermoacoustic prime mover, high acoustic output power can be achieved with a large diameter stack and with a cavity with a large volume attached at the open end of the resonator containing the stack. The combination of resonator and cavity makes the device Helmholtz-like, with special characteristics of the resonant frequencies and quality factor Q. Analysis of its acoustic behavior based on a model of a closed bottle presents features that are useful for the development of such prime movers for energy conversion from heat to sound. In particular, the arrangement produces in the cavity a high sound level, which is determined by the Q of the system. Comparison with a half-wave resonator type of prime mover, closed at both ends, shows the advantages of the Helmholtz-like device.
Experimental determination of the total scattering cross section of individual scatterers in a multiple scattering medium.
Authors: Walker Shane , Roux Philippe , Kuperman William A.
Published: October 2013

A problem of interest in the study of propagation through multiple scattering media is the effective scattering cross section of the individual scattering components. In the multiple scattering regime, one challenge in particular has been to determine the scattering cross section of a component scatterer in the presence of other scatterers. We apply three different methods of experimentally measuring the total scattering cross section of a scattering object. In the first method, the scattering cross of a single scatterer is self-adaptively derived from the attenuation of the coherent field as a function of distance traveled through a multiple scattering medium comprising many identical scatterers. In the second method, the ratio of the coherent to the incoherent fields is used to infer the cross section of a single scatterer in a reverberant cavity. The third method involves a direct measurement of the scattering cross section in free space. We show that the three methods produce similar results.
Parameters for the estimation of loudness from tone-burst otoacoustic emissions.
Authors: Epstein Michael , Silva Ikaro
Published: October 2013

There is evidence that tone-burst otoacoustic emissions (TBOAEs) might be useful for estimating loudness, but appropriate analysis parameters for loudness estimation must first be examined. The purpose of the present work was to collect TBOAE measurements and loudness estimates across a wide range of levels in the same listeners. Both measures were recorded for 1- and 4-kHz stimuli and then analyzed using a wide range of parameters to determine which parameter set yielded lowest mean-square-error estimation of loudness with respect to a psychoacoustical, cross-modality-matching procedure and the inflected exponential (INEX) loudness model. The present results show strong agreement between 1-kHz loudness estimates derived from TBOAEs and loudness estimated using cross-modality matching, with TBOAE estimation accounting for a significant portion of the variance. Additionally, the results indicate that analysis parameters may vary within a reasonable range without compromising the results (i.e., the estimates exhibit some parametric robustness). The lack of adequate parametric optimization for TBOAEs at 4 kHz suggests that measurements at this frequency are strongly contaminated by the ear-canal resonances, meaning that deriving loudness estimates from TBOAEs at this frequency is significantly more challenging than at 1 kHz. [Work supported by Capita Foundation.]
In-utero imaging of developing mouse embryos using a 34-MHz annular array and chirp-coded excitation.
Authors: Mamou Jonathan , Ketterling Jeffrey A. , Aristizábal Orlando , Turnbull Daniel H.
Published: October 2013

High-frequency ultrasound (HFU) is becoming a prevalent modality to image biological tissues with fine resolution. HFU imaging is routinely used for ophthalmologic, dermatological, and small-animal applications. Fine-resolution imaging is obtained at the expense of limited depth-of-field and acoustic penetration depth. In this study, a 34-MHz, five-element annular array was excited using chirp-coded signals and a synthetic-focusing algorithm was used to form images. This imaging approach allowed for the simultaneous increase of depth-of-field and penetration depth. Three-dimensional ultrasound datasets of 12.5-day-old mouse-embryo heads were acquired in utero using chirp and conventional excitations. From the synthetically focused images, brain ventricles and embryonic head were segmented and rendered in three dimensions. Significant artifacts such as segmenting ventricles outside the embryonic head were significantly more pronounced on the conventional-imaging reconstruction than on the chirp-based reconstruction. Furthermore, the total ventricle volume obtained with the chirp (6.3 mm3) was similar to that estimated using a μMRI dataset (i.e., 7.5 mm3). The conventional method greatly over evaluated the ventricle volume (11.4 mm3). The results of this study suggest that HFU chirp-annular-array imaging could become a valuable method for medical imaging applications, such as in utero developmental biology. [Work supported by NIH Grants EB006509 and EB008606.]
Fish hearing and bioacoustics since 1973.
Authors: Fay Richard , Popper Arthur
Published: October 2013

In 1973, we wrote a review in J. Acoust. Soc. Am. that summarized our view of fish hearing and bioacoustics. This presentation looks back on the the major questions we had at the time and how the field has dealt with them, or not, to the present. Some of the issues identified included: (1) the roles of the various otolith organs for hearing; (2) lateral line function and its relation to hearing; (3) sound source localization; and (4) how sound stimulation works for fishes without obvious specializations for pressure reception. There have been major advances in these and other aspects of fish sound reception, but in every case, there are significant unanswered questions. For example, it is still controversial whether the utricle plays a role in hearing in most species, and the functional role of the lagena remains an enigma. However, we now have a much better understanding of lateral line stimulation and function, and we now understand that it is not an “accessory auditory organ,” as was widely assumed initially. Many questions of sound localization are now thought to be answered theoretically, and in some cases empirically, but many critical and fundamental experiments on localization remain to be done.
Transient processes in acoustic resonators.
Authors: Sarvazyan Armen , Ostrovsky Lev
Published: October 2013

The use of ultrasound in resonators for manipulating particles in various biomedical applications is a relatively well studied topic. These studies were mostly concerned with steady-state processes. However, in certain important applications, such as stirring and mixing fluids in microfluidics and biosensors, the time scale of a process plays a crucial role. In this presentation we consider some of these applications. In particular, the radiation force-induced motion of microparticles and microbubbles in a swept-frequency ultrasonic resonator is considered. The particles are forced to move due to switching the resonance modes in a resonator cell, thus providing effective stirring of the fluid. Another field of medical application of standing waves, where transient processes are of crucial importance, is ultrasonic treatment of tissues. In this new field of ultrasonic therapy, standing waves are used for producing lesions in the tissue with simultaneous monitoring the formation of the lesion by automatic controlling parameters of the standing wave field. The spatial and temporal distribution of ultrasound energy in the resonator containing treated tissue portion is theoretically analyzed. Dynamics of temperature changes in the tissue, which is important for optimizing tissue treatment regimes, is evaluated. Experimental data illustrating theoretical results are presented.
Standard anticoagulation for mesenteric vein thrombosis, revealing a ‘zebra’ diagnosis: hereditary haemorrhagic telangiectasia—the dripping truth!
Authors: Aggarwal Aakash , Kahlon Arundeep Singh , Rane Meghan , Banas Emerald
Published: October 2013

A 60-year-old man was treated in the hospital for mesenteric vein thrombosis and discharged home on anticoagulation. On warfarin the patient started to bleed profusely from the nose and tongue. He was evaluated by ENT (ears, nose and throat); a nasal endoscopy revealed several vascular ectasias. Subsequent detailed history and general physical examination established the diagnosis of hereditary haemorrhagic telangiectasia also known as Osler-Weber-Rendu syndrome. On further evaluation, pulmonary arteriovenous malformations were diagnosed on imaging and treated by intervention radiology. In hindsight, the diagnosis could have been made in the general practitioner's office with just a routine thorough history and a physical examination at a new patient visit. We report this case to stress upon the importance of vigilant clinical, medical and family history and a thorough examination to establish an early diagnosis of this not-so-rare entity.