bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of context priming on the auditory potential evoked by semantic analysis (N400).
Authors: Reagor Mary Kathryn , Jerger James , Davis Tara , Martin Jeffrey
Published: October 2009

Context is an important aspect of the perception of ongoing speech. Understanding a speech message in the presence of background noise is aided by knowledge of the context of the message even though the audibility of specific phonemes may be compromised. In this experiment, we used a context priming paradigm to investigate the importance of context to word recognition. We studied the auditory ERP, specifically the N400 response, to presented words which had been previously heard in the context of a story. Results showed that words preceded by a word from the target story elicited a smaller N400 negativity than words preceded by a word from either a different story or from neither story. Thus, words that came from the same story (i.e., had congruent context) were processed with less effort than words from a different story. This “context effect” is discussed in relation to the perception of ongoing speech under difficult listening conditions.
Continuous reconstruction of head related transfer function using optimal-degree spherical harmonics expansion.
Authors: Rao Dan
Published: October 2009

Head related transfer function (HRTF) is a continuous function of spatial direction. In practice, only HRTFs at discrete directions can be measured. In order to obtain HRTFs at unmeasured directions, a continuous reconstruction (or interpolation) procedure is needed. In this paper, a method for continuous reconstruction of HRTF based on optimal-degree spherical harmonics expansion is developed. Expansion coefficients were derived by using the pseudo-inverse method. To address the ill-posed problem in inverse calculation, the expansion degree for each frequency bin was optimized by a heuristic method. This method searches the minimum-norm errors of the reconstructed HRTFs with respect to measured ones which were not used to derive the coefficients. The KEMAR HRTF at 710 directions and a human HRTF at 493 directions were employed in reconstruction. Measured HRTFs from KEMAR or human subject were dived into three groups according to directions, in which the first group of 2/5, the second group of 2/5, and the third group of 1/5 data were used to calculate the expansion coefficients, determine the optimal expansion degree, and evaluate the reconstruction performance, respectively. Compared with the expansion methods using a constant degree for all frequency, the reconstruction performance of the current method is prior.
Errors in the measurements of individual head-related transfer function.
Authors: Zhong Xiao-li , Xie Bo-sun
Published: October 2009

Head-related transfer function (HRTF) describes the transmission process from a point sound source to ears in free field and thus includes the effect of sound diffraction imposed by human anatomical structures. Because each person owns a unique configuration of anatomical structures, HRTF is individual-dependent. Individual HRTF plays an important role in guaranteeing authenticity in virtual auditory display. Measurement is a common way to obtain individual HRTF. In practice, measurement error is unavoidable. Moreover, measurement error and individual characteristic are often blended together, especially at high frequencies where both the measurement error and the individual characteristic are obvious. The object of this work is to evaluate the errors in the measurements of individual HRTF, and extract individual characteristic of HRTF from measured results. HRTFs from six human subjects and KEMAR were measured at 24 spatial positions with six repetitions. Significance of the individual characteristic was examined using analysis of variance. In addition, psychoacoustic experiments were conducted to investigate the audibility of the measurement error and individual characteristic, respectively. Results show that the individual characteristic of HRTF dominates the measured results. [Work supported by Nature Science Fund of Guangdong province (07300617).]
Low order all-pole and all-zero models of human and cat directional transfer functions.
Authors: Al-Sheikh Bahaa , Matin Mohammad , Tollin Daniel, J.
Published: October 2009

Directional transfer functions (DTFs), the directional components of head related transfer functions, are generally measured at finite locations in azimuth and elevation. Thus models are needed to synthesize DTFs at finer spatial resolution than the measured data to create complete virtual auditory displays. Here, minimum-phase all-pole and all-zero models were used for modeling both human and cat DTFs. For the human DTFs, model orders were chosen to achieve specific objective error criteria published in previous studies that were based on subjective listening tests. Because subjective listening tests are not always feasible in animals, objective methods must be used to assess the quality of the DTF reconstructions. Here, the same error criteria reported in subjective tests of human DTF reconstructions were used to constrain models of cat DTFs based on the assumption that if humans cannot discriminate reconstructed versus empirical DTFs for a given objective reconstruction error, then cats will not be able to either provided the reconstruction error is held below that criteria. All-pole and all-zero models of orders as low as 25 were able to model DTFs with errors comparable to previous research findings and preserve the main spectral features in both human and cat DTFs. [Work supported by NIH Grant No. R01-DC6865.]
Frequency regions responsible for activating the efferent response in human ears.
Authors: Walsh Kyle P. , Pasanen Edward G. , McFadden Dennis
Published: October 2009

The nSFOAE is a nonlinear version of the stimulus-frequency otoacoustic emission (SFOAE). In past research, when a wideband noise was presented simultaneously with an ipsilateral 4.0-kHz tone, the nSFOAE to the tone showed a brief hesitation and then a gradual rise that asymptoted after about 100 ms. A similar dynamic response was also seen when the noise was low-pass filtered at 3.8 kHz. However, no dynamic response was seen when the noise was band-passed (400 Hz wide, centered at 4.0 kHz) or high-passed above 4.2 kHz. The interpretation is that the medial olivocochlear efferent system is activated by the wideband and low-pass noises. To identify the frequency components of the noise that are most relevant for activating the rising dynamic response, the nSFOAE was measured for the 4.0-kHz tone in the presence of 400-Hz bands of noise having a spectrum level of about 30-dB SPL and centered at 3.6, 3.2, 2.8, 2.4, and 2.0 kHz. Further exploration was done with noise bands 200 Hz in width and of 33-dB SPL spectrum level, as well as with additional frequencies of the tone. There were individual differences in the frequency regions yielding the maximum dynamic nSFOAE response. [Work supported by NIDCD.]
Spectral shaping of system response using an array of subordinate oscilator.
Authors: Petersen Kalin , Judge John
Published: October 2009

This work demonstrates that the spectral response of an oscillating structure can be tailored by attaching one or more subordinate oscillators with designed properties. A closed form governing equation of motion is derived for the coupled system composed of the primary system and the subordinate oscillator array. Examples show that the frequency response can be tailored to desired shapes by prescribing the distributions of the dynamic properties in a relatively small array of such subordinate oscillators. In these examples, the number of attached oscillators is less 100 and having mass that is less than 1% of the mass of the primary structure, it is possible to tailor frequency response functions of the primary oscillator to have a nearly linear phase or constant amplitude over a frequency band of interest. The frequency range over which spectral shaping is achieved is determined by the band of the attached oscillators in isolation. We show that the common analytic design methodology for determining a dynamic vibration absorber represents the limiting case of a single oscillator in the subordinate set, but that increasing the number of subordinate oscillators (without increasing the total added mass) offers a number of advantages in reshaping the dominant system spectral response.
Toward high-fidelity computational fluid dynamics based tools for phonosurgery.
Authors: Mittal Rajat , Zheng Xudong , Xue Qian , Beilamowicz Steven
Published: October 2009

Vocal fold paralysis/paresis resulting from stroke accounts for nearly a third of all voice disorders diagnosed in the US. Stoke can damage the nerves that drive vocal fold adduction, leading to incomplete glottal closure and hence an inability to produce sustained vocal-fold vibrations. One common treatment for this pathology is medialization laryngoplasty wherein an implant is inserted into the paretic vocal fold in such a way as to force it to the glottal midline. If done properly, this procedure can lead to full voice recovery. However, the implant shape/location has to be determined intra-operatively through a trial-and-error process, and this can lead to a fairly high revision rate. The long term objective of the current project is to develop a computational fluid dynamics based tools that can help with the preoperative planning of this surgical procedure and thereby reduce the revision rate of this surgery. The tool is based on a coupled immersed-boundary-finite-element solver that can solve for the glottal flow as well as flow induced vibration of the vocal folds. We are currently using the solver to study the fundamental biophysics of phonation, and results from these studies will be presented. [Work supported by NIH.]
An inhomogeneous mechanical replica of the vocal folds.
Authors: Pelorson Xavier , Van Hirtum Annemie
Published: October 2009

In parallel with theoretical modeling, in-vitro mechanical replicas of the human larynx have become very popular in the speech science community. These experimental devices are indeed extremely useful in order to evaluate the relevance and the accuracy of physical models of speech production. In this paper, a new mechanical model of the vocal folds is presented. It consists of a self-oscillating structure made of various layers with different mechanical properties (silicone, rubber, and/or liquid). The elasticity of the deeper layer can be controlled by stress/strain system. Although very simplified, such mechanical model is intended to replicate an inhomogeneous structure comparable to the human vocal folds one. The mechanical replica is then mounted on a air reservoir whose pressure can be controlled. The pressure upstream and downstream of the replica are measured together with the mechanical displacement of the artificial folds, thanks to a laser device. Typical examples of measurements will be presented for various alimentation pressures and elasticity conditions. The relevance of the observed effects with respect to human phonation and the possibility to explain them using simple mass-spring mechanical models will be discussed.
Experimental observations on the influence of supraglottal flow structures on phonation.
Authors: Zhang Zhaoyan , Neubauer Juergen
Published: October 2009

The supraglottal flow has been shown to exhibit many complex phenomena such as vortex shedding, jet oscillation, and recirculation. However, the influence of such airflow features on phonation is still unknown. The objective of this study is to evaluate the influence of the supraglottal flow structures on phonation characteristics. In a mechanical model of phonation, the interaction of the supraglottal flow with vocal folds was studied by using vocal tract tubes of different lengths mounted at different off-center positions and by disturbing the flow with cylinders of different diameters. Preliminary results show that, at normal phonation conditions, changes in the supraglottal flow structures did not lead to noticeable changes in phonation threshold and sound quality. However, for vocal fold models simulating pathological conditions, disturbing the supraglottal flow led to significant changes in phonation frequency, amplitude, and perceived sound quality. Possible mechanisms that could explain the observed difference will be discussed. [Work supported by NIH R01 DC009229.]
Empirical results using laryngeal models M5 and M6.
Authors: Scherer Ronald C. , Torkaman Saeed , Kucinschi Bogdan R. , Li Jun , Zhai Guangnian , Afjeh Abdollah A. , Fulcher Lewis P.
Published: October 2009

Laryngeal models M5 two dimensional and M6 [three dimensional and eccentric] contribute empirical data on intraglottal and transglottal pressures and flows for numerous glottal configurations. M5 provides results for both symmetric and oblique glottal shapes. M6 has a 3-D glottis (the membranous glottis width is greatest at the A-P midpoint) and is eccentric (with modeled arytenoid cartilages blocking the posterior glottis so that the glottis acts as an eccentric orifice). Results from these models typically yield asymmetric pressures which will be presented and discussed. M5 obliquity results will be used in a multimass model of phonation to indicate the potential effects of asymmetric pressures on glottal flow and stability. [Research supported by NIH Grant #2R56DC003577].
Overview of Kalman and particle filters for acoustic applications.
Authors: Michalopoulou Zoi-Heleni , Gerstoft Peter , Yardim Caglar
Published: October 2009

In this talk, the basic principles behind Kalman and particle filtering are presented. These filters are recursive Bayesian estimators for the state of a dynamic system from a series of noisy measurements. Starting from the simple Kalman filter, we focus on computationally efficient particle filters or sequential Monte Carlo methods. These are often used to formulate and solve problems in a Bayesian framework and are the sequential analog of Markov chain Monte Carlo approaches. Applications where complex problems in acoustics are solved with particle filters will be shown. We will examine source localization and tracking, geoacoustic inversion, and tracking of acoustic field features and discuss the advantages of specific filtering techniques. [Work supported by ONR.]
Extended Kalman filters for tracking time-frequency striations.
Authors: Zurk Lisa M. , Oesterlein Tobias , He Chensong , Quijano Jorge
Published: October 2009

The time-frequency structure of the received intensity from a moving source in a shallow water channel is typically observed as striations in the target spectrogram. The relationship between the slope of the striations and the source location can be described with the waveguide invariant, and this relation can be incorporated in the sonar signal processing for improved detection or tracking. However, incorporating this structure requires a robust method of estimating the presence and location of the target striations. In this paper a multi-target extended Kalman filter is presented to track the striations. The filter identifies each striation as a potential target, and then uses the invariance relationship to execute the Kalman update stage. The physics of the channel are further incorporated through the imposition of multi-track consistency and bounds on striation migration. In addition to the striation tracker, a second algorithm is presented which is appropriate for spectrograms with insufficient resolution (either in time or frequency) to visualize the striations. This second algorithm provides a confidence test for a given track hypothesis by accumulating likelihood information along a predicted striation. Results of both algorithms are presented for simulated and real active sonar data.
Bayesian source tracking in an uncertain ocean environment.
Authors: Dosso Stan E. , Wilmut Michael J.
Published: October 2009

This paper considers matched-field tracking of a moving acoustic source when properties of the ocean environment (water column and seabed) are poorly known. The goal is not simply to estimate source locations but to determine track uncertainty distributions, thereby quantifying the information content of the tracking process. To localize and track low-level sources, acoustic data collected for multiple time samples (corresponding to multiple source positions) are inverted simultaneously, with constraints included on the maximum allowable motion between samples. This increases the information content over sequential tracking approaches such as particle filtering, but also increases the dimensionality and difficulty of the inversion. A Bayesian formulation is applied in which the posterior probability density (PPD) is integrated over unknown environmental parameters to obtain a time-ordered sequence of joint marginal probability surfaces over source range and depth. Marginal PPDs are computed numerically using Metropolis–Hastings sampling over environmental parameters (rotated into principal components and applying linearized proposal distributions) and two-dimensional Gibbs sampling over source locations. The approach is illustrated using Mediterranean Sea data, and tracking information content is considered as a function of data quantity (number of time samples and frequencies processed), data quality (signal-to-noise ratio), and level of prior information on environmental parameters.
Spatial and acoustic feature extraction by particle filtering for efficient noise reduction.
Authors: Mizumachi Mitsunori
Published: October 2009

Noise reduction can be achieved relying on something related to spatial and acoustic features: a direction-of-arrival (DOA), a fundamental frequency, harmonicity, and so on. It is natural that a suitable noise reduction approach is different depending on the available features, because no all-purpose noise reduction method has been established under every possible acoustic condition. To achieve noise reduction effectively and efficiently, it is important to explore and acquire well-suited spatial and acoustic features at all times. Observed acoustic signals originate in some dynamic systems such as a speech production system and behavior of continuous sound source movement, which can be represented by the Markov model in the perspective view, but they are usually distorted by noise and reverberation. In this paper, both feature extraction and feature tracking are attempted by using particle filters aiming at achieving efficient noise reduction. Particle filters can also bring a new feature of the reliability of each DOA estimate based on the effective sample size through the state estimation of spatial features [Mizumachi, Proceedings of the 156th ASA meeting]. In this paper, spatial and acoustic feature extraction by particle filtering is evolved into noise reduction. [Work supported by NEDO, Japan.]
Blind deconvolution of remote-source signals from acoustic array recordings in multipath environments.
Authors: Hossein Abadi Shima , R. Dowling David
Published: October 2009

Reconstructing the signal from a remote source in an unknown multipath environment is a task commonly known as blind deconvolution. The existence of generic features of underwater sound fields, propagating modes or ray paths, may be exploited for blind deconvolution via artificial time reversal (ATR), [Sabra and Dowling, J. Acoust. Soc. Am. 116, 262–271 (2004)] from vertical array recordings. ATR uses a weighted sum of array recordings to determine a frequency-dependent phase correction that aligns the various mode or ray-path arrivals at the receiving array to form an estimate of the original source waveform. A description of ATR will be presented along with parameter studies of ATR performance for simulated signals in a 100-m-deep Perkeris waveguide, and for airborne sounds measured in a reverberant laboratory. Here, the correlation coefficient between original and the ATR-reconstructed signals will be presented as a function of the number and spacing of array elements, and signal characteristics (frequency and bandwidth). The limitations imposed by noise will be quantified for the measured signals. Possible applications of ATR will be briefly discussed; these include reducing inter-symbol interference in underwater communication, tracking and identifying remote sources, and monitoring marine mammals that vocalize. [Work supported by ONR Code No. 321OA.]
Three-dimensional data analysis for acoustic measurements of a seismic airgun array.
Authors: Tashmukhambetov Arslan M. , Ioup George E. , Ioup Juliette W. , Sidorovskaia Natalia A. , Niculescu Anca , Newcomb Joal J. , Stephens James M. , Rayborn Grayson H. , Summerfield Phil
Published: October 2009

The Source Characterization Study 2007 measured the three-dimensional acoustic field of a seismic airgun array. The Littoral Acoustic Demonstration Center performed the experiment, collecting acoustic and related data on three moored hydrophone arrays and one ship-deployed hydrophone array which together spanned the full water column. Sensitive and desensitized phones were deployed at each position to extend the dynamic range. An ultra short baseline localization system was deployed with the EARS moorings to provide array shape. With post analysis this results in time-dependent positions for each of the acoustic sensors. Every channel is calibrated. A seismic source vessel shot a series of lines designed to give detailed angle and range information concerning the field of the primary arrival. The experiment was conducted in the western Gulf of Mexico between the East Break and Alamos Canyon regions. Peak pressures, sound exposure levels, total shot energy spectra, and one-third octave band analyses are measures used to characterize the field. Images of these quantities are generated to show dependence on emission and azimuthal angles and range. [Research supported by the Joint Industry Programme through the International Association of Oil and Gas Producers.]
Use of high performance computing resources for underwater acoustic modeling.
Authors: Niculescu Anca M. , Sidorovskaia Natalia A. , Achi Peter , Tashmukhambetov Arslan M. , Ioup George E. , Ioup Juliette W.
Published: October 2009

The majority of standard underwater propagation models provide a two-dimensional (range and depth) acoustic field for a single frequency point source. Computational resource demand increases considerably when the three-dimensional acoustic field of a broad-band spatially extended source is of interest. An upgrade of the standard parabolic equation model RAM for use in a high-performance computing (HPC) environment is discussed. A benchmarked upgraded version of RAM is used in the Louisiana Optical Network Initiative HPC-environment to model the three-dimensional acoustic field of a seismic airgun array. Four-dimensional visualization (time and space) of the generated data volume is also addressed. [Research supported by the Louisiana Optical Network Initiative, TeraGrid Fellowship, and the Joint Industry Programme through the International Association of Oil and Gas Producers.]
Experiment results of time-reversal communication in the deep ocean at the range of 300 km.
Authors: Shimura Takuya , Ochi Hiroshi , Watanabe Yoshitaka , Hattori Takehito
Published: October 2009

The research is being conducted to realize communication with a long cruising AUV in the deep ocean using time reversal. We have proposed the method of combining time reversal and adaptive equalization. In our previous at-sea experiments, the performance of time-reversal communication was confirmed at the range of 10–100 km with a virtual array. In our latest sea-trial, experiments of passive time-reversal communication were executed at the range of 300 km with a real receiver array. As a probe signal, chirp pulses and M-sequence pulses were used. The data transmission speed was 50 and 100 bps. The source was suspended from the research vessel and the 20 channel receiver array was moored. Thus, Doppler effect was induced due to the ship drifting at the speed of approximately 0.25 m/s at maximum. Nevertheless, such effect is compensated and demodulation with no error is achieved with the proposed method. The results of using chirp pulses are inferior to the results of using M-sequences because of sidelobes of the chirp correlation. The results of using longer M-sequence are degraded due to Doppler effect.
Remote sensing with ambient noise.
Authors: Gerstoft Peter , Siderius Martin
Published: October 2009

Ambient noise is ubiquitous in the ocean. For many years, this noise has been considered the unwanted part of the acoustic signal. However, recent studies have shown that the noise itself contains valuable information about properties of the ocean, Earth, and atmosphere. For example, distant storms have been observed using measurements of low-frequency (0.1-Hz) noise that has propagated through the Earth’s core. Wind speed over the ocean has also been determined hundreds of kilometers away using noise measurements at coastal observing stations. At higher frequencies, surface wave noise due to breaking waves has been used to image the seabed and reveal details of the sub-bottom structure. In general, these techniques are based on cross-correlations of noise signals measured at different locations. These cross-correlations produce an estimate of the Green’s function (impulse response) between the two points which can be used to characterize the medium. With concerns over the impact of anthropogenic sound on the marine environment it is not surprising that remote sensing with naturally occurring noise has become a hot topic in acoustical oceanography. Essential components of noise processing will be described along with examples illustrating applications. [Work supported by ONR.]
Helmholtz equation least squares based panel contribution analysis.
Authors: Mylavarapu Sandeep , Wu Sean
Published: October 2009

This paper presents a methodology for analyzing relative contributions from individual panels toward the sound pressure field inside a large enclosure, for example, an aircraft cabin, automobile passenger compartment, etc., due to sound transmission from external acoustic sources, structural vibrations, or their combinations. In this approach, the field acoustic pressure is correlated directly to the normal component of the time-averaged surface acoustic intensity, which is reconstructed based on acoustic pressures measured by microphones in the near field of a structure using Helmholtz equation least squares method. The normal surface acoustic intensities are calculated on individual panels; therefore their relative contributions toward sound radiation at any field point can be evaluated and ranked. This approach is advantageous over those based on a reciprocally measured transfer function [Hald et al., Internoise (2006); Wolff, Internoise (2007)] in that panel contributions are done by taking a single set of measurements, and results are valid for all interior points. To validate this methodology, numerical simulations are conducted for a spherical enclosure for which the analytic solutions are readily available. Specific examples of numerical simulations include a dilating spherical and a partially vibrating sphere. Finally, experimental results using this methodology for a full-size vehicle are demonstrated.
Boundary layer pressure fluctuation measurements in transitional and turbulent flow.
Authors: Galib Thomas A.
Published: October 2009

Pressure fluctuations were measured for external flows over an axisymmetric surface. Measurements were made in laminar, transitional, and turbulent flow using piezoelectric pressure transducers. The entire surface (including the pressure transducers) was coated with a 1/16-in. thick elastomer, in order to ensure a smooth surface. All measurements of boundary layer transition were made in an adverse pressure gradient. Results showed that root-mean-square pressure fluctuation levels during transition were as much as 15 dB higher than for fully developed turbulent flow. The transitional spectra were dominated by Tollmien-Schlichting waves, and associated nonlinearities. The spectra of Tollmien-Schlichting waves during amplification and subsequent transformation to turbulence are shown nondimensionally in comparison with Bakewell’s turbulence spectral density.
Large building isolation with seismic restraint.
Authors: Phillips James
Published: October 2009

Isolating a large building such as a concert hall or multi-story condominium necessarily requires structurally separating the isolated building from the foundation. The structural support is then provided by resilient bearings which must properly support the building gravity load and provide seismic restraint and structural stability. The best acoustical results are achieved with natural rubber bearings sized to support the gravity load at columns and loadbearing walls. Lateral support for wind and seismic loads is then achieved, without compromising the isolation, through the installation of lateral support bearings in equal and opposite pairs in both directions. The lateral loads are transmitted to the columns or loadbearing walls via the structural floor above the bearings functioning as a transfer slab. The equal and opposite preloaded pair concept for lateral restraint was developed to achieve an assembly with the bearings always in compression regardless of load or deflection. This avoids any need for embedded plates or bolts which could cause tension in the concrete structural elements. The history of the development of the preloaded lateral restraint rubber bearing concept is presented along with examples of successful application to concert halls and other structures.
Acoustical performance of wall assemblies containing wood structural elements.
Authors: LoVerde John , Dong Wayland
Published: October 2009

There has been little historical research within the acoustical community regarding the sound isolation properties of wall assemblies that include structural elements. On most buildings, many of the wall assemblies, including exterior walls, demising walls, and corridor walls, require wood shear panels and/or posts to be incorporated into their design for structural reasons. However, most common acoustical designs have not been acoustically tested with the presence of wood structural elements. Acoustical test results for such wall assemblies are presented. Since a conventional approach is to assume that a plywood shear panel performs similarly to a layer of gypsum board, the walls including a wood shear panel will be compared to equivalent assemblies where that layer is gypsum board. Additionally, field acoustical test results for walls including shear panels shall also be presented and compared with the laboratory tests, and translation of laboratory to field acoustical performance for these constructions will be discussed.
The soundscape of a nearshore reef near an urban center.
Authors: Au Whitlow W. L. , Richlen Michael
Published: October 2009

An acoustic monitoring system in the nearshore waters of the south shore of Oahu is a part of the Kilo Nalu nearshore coral reef observatory (http://www.soest.hawaii.edu/OE/kilonalu/). The underwater housing containing the hydrophone, amplifier-filter, A/D converter, and an ethernet converter is located 690 m from shore at a depth of 22 m. Acoustic signals are digitized at a rate of 24 kHz, and sent to shore on a fiber optic link to a laptop computer and are stored on a disk drive. Snapping shrimp sounds are the most prevalent biological signals and are always present. Other sounds from biological organisms include humpback whales (during their winter season in Hawaii), fish, and dolphins. However, the soundscape during daylight hours is dominated by small boat sounds as a variety of vessels are regularly detected and the signal levels from these boats are considerable higher than the biological sounds. Only humpback whale songs have the chance of being detected in the presence of boat sounds, whereas other biological sounds tend to be overwhelmed. During the day, sounds from other biological organisms can only detected between boat sounds. Boat sounds usually stop after dusk providing the best environment for detecting biological sounds.
Non-random patterns of acoustic interactions in chorusing bullfrogs.
Authors: Simmons Andrea M. , Bates Mary E. , Knowles Jeffrey
Published: October 2009

Male bullfrogs form choruses to vocally advertise for females and to announce territory occupation to rival males. In dense choruses, calls of individual males may temporally overlap due to the large numbers of vocalizing neighbors. Overlapping calls may be a deliberate communicative strategy, perhaps to form a more salient auditory object in order to effectively guide females to a particular location within the chorus. We used a custom-written MATLAB program to simulate the proportions of overlapping and nonoverlapping calls in five mock choruses, and then compared model output to empirical data from natural choruses of equal size. The simulation assumed that each bullfrog called independently of his neighbors according to a Poisson process so that overlapping calls occur randomly rather than through cooperation. In four of the five empirical recordings, the number of overlapping calls was significantly smaller than the averages produced by corresponding simulations, indicating that more males vocalized together in bouts than predicted by the random simulation. Empirical and simulated data also differed significantly in the remaining chorus, but in the opposite direction. These data suggest that overlapping calls may confer some communicative advantage. [Work supported by NSF Advance program.]
Dynamical interactions in a green treefrog chorus.
Authors: Jones Douglas L. , Jones Russell L. , Ratnam Rama
Published: October 2009

In southeast Texas male green treefrogs (Hyla cinerea) assemble in dense choruses and call for several hours every night to attract females. The call is a short “quank” lasting about a 100 ms, with a variable call interval of about 400 ms. Individuals call from dense vegetation surrounding the breeding area, occupying positions that range in elevation from water level to several meters above the ground. The high call-rate and duty cycle combined with their three-dimensional spatial distribution present challenging problems for signalers and receivers and for human observers. It is qualitatively apparent that within a large natural chorus, individuals dynamically adjust their calling to avoid overlap with other callers. However, the dynamical interactions and calling strategies have not been quantified. Here, a 15-microphone array was deployed within the breeding site in the vicinity of one group of callers, and the locations and call patterns of individuals were extracted by acoustic beamforming. The results show that an individual pays attention to only a few of the neighboring males and times his calls to avoid call collision. When a collision occurs one of the individuals will delay the subsequent call by approximately half a call interval to avoid further collision.
A glimpse of the world through the voice of the echolocating bat.
Authors: Moss Cynthia , Chiu Chen , Surlykke Annemarie
Published: October 2009

Bats echolocating in the natural environment face the formidable task of sorting echoes from closely spaced obstacles and prey, which may be mixed with sonar signals of nearby conspecifics. This talk will review behavioral strategies used by the big brown bat, Eptesicus fuscus, to solve such auditory scene analysis tasks. The sonar beam emission pattern of the big brown bat is directional, but broad enough to collect echo information from objects within a 60–90 deg cone, which would enable simultaneous inspection of adjacent objects. Data show, however, that bats shift their sonar gaze to inspect closely spaced objects sequentially and analyze sounds source direction and distance to track auditory objects as they fly. When bats forage in groups, they face the challenge of sorting echoes from their own calls from echoes and calls of neighboring bats. Research findings demonstrate that bats make adjustments in the spectral characteristics of calls when flying with conspecifics, and the magnitude of these changes depend on the baseline similarity of calls produced by individual bats when flying alone. These recent discoveries from studies of bat echolocation point to the general importance of an animal’s action to its analysis of natural scenes.
Defocusing of echo-delay images for clutter rejection in echolocating bats.
Authors: Bates Mary E. , Simmons James A.
Published: October 2009

Echolocating big brown bats emit ultrasonic FM sounds containing two prominent harmonics (FM1 and FM2) and perceive target distance from echo delay. Each broadcast and its echoes are processed by time-domain mechanisms incorporating neuronal delay-lines for spectrogram correlation. Pulse-to-pulse variability requires the bat to store a template of the FM sweeps in each broadcast to recognize its exact echoes. Ordinarily, gradations of mismatch, or decorrelation, between echoes and broadcasts would lead to a correspondingly graded decline in delay accuracy. However, when the relation between FM1 and FM2 is gradually disrupted, bats abruptly lose delay acuity through a process that amounts to deliberate defocusing of the image. Bats actually have two computational pathways for perception of delay—one involving overall delay to determine target range, and the other involving delay differences between glint reflections to determine shape, extracted from the interference spectrum between the overlapping reflections. Defocusing occurs in the shape, or fine delay part of the image, possibly due to failure of the spectrally based transformation process to converge upon a simple solution that would depict a manageably small number of glints from a regular pattern of interference notches. [Work supported by ONR and NIMH.]
Understanding the relationship between marine mammals and their environment in the Bering Sea.
Authors: Miksis-Olds Jennifer L. , Parks Susan E. , Nystuen Jeffrey A.
Published: October 2009

Passive aquatic listening (PAL) instruments were deployed on sub-surface moorings along the 70-m isobath of the Bering Sea shelf. PALs operate according to an adaptive sampling protocol as opposed to recording continuously, thus enabling data collection for a full year at a sampling rate of 100 kHz. Year long time series indicate that marine mammal vocalizations dominate the regional soundscape in the late winter/early spring time period. Species acoustically identified include North Pacific right, killer, beluga, humpback, fin, and bowhead whales, plus bearded seal and walrus. Synoptic measurements of prey abundance with three-frequency active acoustic sensors, ice cover, and physical oceanographic processes provide vital information for understanding the relationship between marine mammals and their continually changing environment. These data represent important baseline measurements of environmental variability, marine mammal species richness, and temporal distribution of animals in an area of the world that is rapidly transforming due to global climate change. [Research supported by ONR.]
Anderson localization of ultrasonic waves in three dimensions.
Authors: Page John , Strybulevych Anatoliy , Hu Hefei , Skipetrov Sergey , van Tiggelen Bart
Published: October 2009

There is currently a resurgence of interest in Anderson localization, where multiply scattered waves become “trapped” through interference in a very strongly scattering medium. This interest is fueled by theoretical and experimental advances, especially for classical waves, where unambiguous experimental evidence for localization in three dimensions has remained elusive until recently. In this talk, progress in demonstrating the localization of ultrasound in a “mesoglass,” made by assembling aluminum beads into a three-dimensional (3-D) elastic network, is summarized. Measurements of the time-dependent transmission of the ultrasonic intensity, as well as the dynamic transverse confinement of the waves due to localization, are discussed. The data are well described by a new self-consistent theory of the dynamics of localization, providing an important validation of this theoretical approach and enabling the localization length to be measured. Finally, evidence for non-Gaussian statistics of the transmitted intensity is discussed, consistent with values of the Thouless conductance ɡ less than 1. This is the first time that these three different fundamental aspects of Anderson localization (time-dependent transmission, transverse confinement of the waves, and statistics) have been studied simultaneously, providing very convincing evidence for 3-D localization of ultrasound in these materials.
Numerical study of a spectral approach to solve integral equation formulation of the high-frequency acoustic multiple scattering problem by disks.
Authors: Antoine L. Xavier , Ramdani Karim , Thierry Bertrand
Published: October 2009

This aim of this talk is to propose a new numerical method for solving the multiple scattering problem of an acoustic wave by circular cylinders. The situation where the wavelength is small compared to the characteristic size of the cylinders is analyzed in detail here. It is known that this framework implies specific numerical difficulties since it leads to the numerical solution of a large size linear system. The proposed approach is based on computing the scattered field as the solution of an integral equation. Writing this integral equation in a Fourier basis and using a suitable truncation of these Fourier series and a preconditioned Krylov iterative solver (GMRES), an efficient and robust numerical procedure is built. Computational simulations will be provided for solving high frequency multiple scattering problems by random configurations of circular obstacles.
Simulation of ultrasonic scattering in breast tissue based on cell and tissue morphology.
Authors: Doyle Timothy E. , Hart Vern , Ambrose Brady
Published: October 2009

High-frequency ultrasonic spectroscopy is a promising approach for the in vivo detection of cancer in applications such as margin assessments during breast cancer surgery. To advance this approach, a multiple scattering model was developed to more fully understand and analyze ultrasonic backscatter data in the 10–100-MHz region from breast tissues in various stages of tumor progression. The model uses an iterative multipole approach to simulate the multiple scattering of shear and longitudinal waves between nucleated cells in a histologically accurate tissue representation. Previously, concentric spheres were used to model the nucleus and cytoplasm of cells organized in complex, hierarchical tissue structures consisting of alveolar cavities and up to 2075 cells [Doyle et al., J. Acoust. Soc. Am. 125, 1751–1767 (2009)]. The simulations used addition theorems to model multiple scattering and showed significant spectral changes that correlated with tumorigenesis. To increase the fidelity of the simulations, the scattering model has been expanded to incorporate spheroidal and cuboidal cells, non-centered nuclei, mixed tissue types, and duct-like channels representing the three-dimensional luminal structure in breast tissue. Theory, simulation results, and experimental data will be presented. [Work supported by NIH 1R21CA131798-01A1.]
High-frequency wave propagation in suspensions of elastic particles: Experimental validation of a time domain numerical simulation.
Authors: Haiat Guillaume , Galaz Belfor , Berti Romain , Taulier Nicolas , Amman Jean-Jacques , Urbach Wladimir
Published: October 2009

Sound propagation in suspensions of elastic particles immersed in a fluid is a difficult problem due to (i) the random distribution of the particles and (ii) possible multiple scattering and mode conversion effects. The ultrasonic propagation in suspensions has mostly been studied in the frequency domain and time domain approaches may also be of interest. Here, two-dimensional finite difference time domain numerical simulations of ultrasonic propagation in suspensions of polystyrene 6-μm-diameter microspheres immersed in water were performed around 50 MHz. The numerical results were compared with the Faran analytical model, leading to a maximum difference of 15%, which constitutes a validation of the numerical approach. Experiments were carried out in transmission and backscattering modes. The attenuation coefficient 50 MHz [α(50)], the ultrasonic velocity (V) and the relative backscattered intensity (IB) were measured for different concentrations (from 2 to 25 mg/ml). Each experimental ultrasonic parameter was successfully compared to the numerical results obtained by averaging the ultrasonic parameters derived from 15 different spatial distributions of the micro-disks. The good agreement between the experimental and numerical results constitutes a validation of the approach, which may be used in the future in different applications such as ultrasound contrast agent.
Effects of musical training on brain development.
Authors: Trainor Laurel
Published: October 2009

The auditory cortex builds representations of the auditory environment based on the characteristics of its input. I will present EEG and MEG data showing that, compared to non-musicians, adult musicians have enhanced responses to isolated musical tones, melodic sequences, and simultaneous melodies. Whether these differences are the result of musical experience is explored through training studies in adults and longitudinal studies comparing children engaged in musical lessons with children engaged in other activities. It will be shown that auditory sensory representations undergo a protracted developmental trajectory, not reaching adult states until well into the teenage years. Furthermore, the effects of musical experience can be seen in children as young as 4–5 years of age for both sensory and attentional components of the event-related potential. High-frequency oscillatory EEG activity (induced gamma band), which is associated with executive control, attention, and memory, emerges after 1 year of music lessons in children of this age, but is not seen in children who are not taking music lessons. Thus any benefits of musical training for other cognitive domains is likely mediated by the development of superior executive functioning.
Musical ability and cognitive abilities.
Authors: Schellenberg Glenn
Published: October 2009

Does music make you smarter? Associations between music and cognitive functioning are notable only if the benefits apply reliably to nonmusical abilities and if music is unique in producing the effects. Such associations could arise either from music listening or music lessons, and there is no reason to believe that observed associations between cognitive abilities and music listening should parallel those involving music lessons. The available evidence indicates that music listening leads to enhanced performance on a variety of cognitive tests, but that such effects are short-term and stem from the impact of music on arousal level and mood, which, in turn, affect cognitive performance; experiences other than music listening have similar effects. Music lessons in childhood tell a different story. They are associated with small but general and long-lasting cognitive benefits that cannot be attributed to obvious confounding variables such as family income and parents education. Nonetheless, such associations may not be evident in samples of adults with many years of music lessons or among professional musicians. Moreover, the mechanisms underlying observed associations between music lessons and cognitive abilities have yet to be determined.