bluuebunny/crossref_metadata_2025 huggingface dataset:
Krylov methods in inverse scattering and imaging
Authors: Barbone Paul E. , Feijóo Gonzalo R. , Oberai Assad A.
Published: October 2011

Inverse scattering requires the measurement and inversion of a compact operator. The compactness of the operator implies that its range is low dimensional (i.e., sparse.) This implies the theoretical possibility of measuring the full operator with relatively few measurements and inverting it on a sparse basis. One issue, however, is that the basis on which the operator is sparse is unknown a priori. We show that Krylov methods can be used to simultaneously identify an efficient basis for the measurements and facilitate the inversion for imaging purposes. In particular, we show how imaging via Multiple SIgnal Classification (MUSIC) and by Krisch's factorization method can be efficiently implemented in a Krylov space context. This method allows us to make most efficient use of all available acoustic sensors with few measurements and with minimal mutual interference.
Optimization of tuning and matching of broadband transducers with power switching amplifiers
Authors: Bachand Corey , Aronov Boris , Brown David A.
Published: October 2011

Underwater transducers for broadband communication rely on effective tuning and matching to a power amplifier for maximum signal bandwidth and efficiency. This analysis follows a systematic approach to design an efficient and effective broadband acoustic transmit system. Power switching (class D) amplifiers use a variety of modulation schemes to reduce the losses incurred at the high power amplification stage. Lowpass filtering at the output stage of the switching amplifier is often employed to attenuate the high frequency carrier signal from the modulation stage. A matching transformer steps up the voltage delivered to the transducer. The tuning network can be designed to provide optimum cancellation of reactance over a wide band, thus improving the power factor bandwidth.
Limits of dissipative coefficients in piezoelectric transverse isotropic materials
Authors: Martin Gordon E.
Published: October 2011

This paper relates to limiting forms of complex coefficients in passive piezoelectric systems due to hysteretic dissipation The specific application is polarized ferroelectric ceramic materials. The research required three features. (1) Mathematical models require the theory of physically realizable networks with distributed components like electrical transmission lines. Such theory is well established for discrete components and special forms of distributed components. Theory for the general case is reported here. (2) Passive systems cannot create energy so complex coefficients of mathematical models must have limiting values for both real and imaginary coefficients of the constitutive matrices. (3) The mathematical model can be expressed in complex symmetric form. It is proved all imaginary parts of matrix coefficients have changes of first order due to small dissipative perturbations. For piezoelectric spectroscopy purposes, measured immittances have two kinds of limits due to the addition of small dissipative effects. They cause small changes in complex values and corresponding frequencies of zeros and poles. It is proved (a) all critical immittance values have small changes to first order and (b) all corresponding frequencies have small shifts to second order.
Evaluating piezocrystal and piezoceramic transducer bandwidth and effectiveness
Authors: Bachand Corey , Brown David A. , Aronov Boris
Published: October 2011

Conventional piezoceramic transducers offer moderate bandwidth and performance to serve the majority of underwater acoustic applications. The manufacturability of piezoceramic elements in a variety of shapes (bars, cylinders, and hemispheres) makes them a cost-effective solution in may transducer designs. However, the emergence of piezocrystals in transducer designs has significantly increased the usable bandwidth while reducing the device footprint. This is enabling in terms of size and weight for use on mobile platforms (UUVs), especially when considering that one piezocrystal transducer may replace several piezoceramic transducers and reduce the number of hardware (power amplifier) channels. There are still fabrication and operational challenges with piezocrystal transducers that need to be overcome before they are widely adopted in the underwater community.
Comparison and verification of analogous circuit models for dynamic moving-coil transducers
Authors: Price Rex P. , Marquez Daniel R. , Leishman Timothy W.
Published: October 2011

For decades, analogous circuits have been used to model the electro-mechano-acoustical properties of moving-coil transducers. In recent years, many enhanced models have been proposed to improve the accuracy of their estimated voice-coil impedances. In this work, an iterative complex curve-fitting routine has been used to best fit and compare the various models to the measured complex input impedance data of several loudspeaker drivers in free air. The estimated blocked electrical impedance of each driver was extracted and used to predict its frequency-dependent cone velocity while under operation. Actual driver cone velocities were measured experimentally using a scanning laser Doppler vibrometer, and the predictions were compared to further substantiate the accuracy of each model. The results highlight those models with the greatest predictive capabilities and reliability.
Systematic circuit model construction for complex interconnected acoustic systems
Authors: Wilson Preston S.
Published: October 2011

Complex, highly interconnected acoustic systems can be difficult to model for students and inexperienced practitioners. The systematic lumped-element circuit model construction method presented here is easy to learn and teach and allows for quick and easy, error-free circuit model construction. The present author discovered the method in a book by Mario Rossi [Acoustics and Electroacoustics, Artech House Publishers (1988)] and has included it in the electroacoustic transducers course taught at The University of Texas at Austin since 2003.
Understanding sound wave propagation using computer animations
Authors: Arenas Jorge P.
Published: October 2011

It is well known that sound waves are often difficult, if not impossible, to visualize which makes their nature and effects much more difficult to explain than those of other kinds of waves. In this article, a visualization tool for enhancing the students' learning process for a fundamental of acoustics course is reported. The visualization is done through particle displacement computer animations of different sound propagation cases using a simple Matlab script. Several examples that can enhance the material discussed during class time are presented, in particular those topics involving diffraction of sound waves. It is observed that visual displays used during lectures improve the students' retention of new material. Students seem to make better association between wave motion and particles in a medium. A visual advantage of the particle displacement animations is that they use tangible items to represent the invisible process, by visualizing the invisible particles of air as dots on the computer screen. In addition, this instructional tool used to visualize sound fields enhances the understanding of many conceptual aspects underlying sound wave motion and can be used to motivate a discussion of the wave equation later.
A student-friendly algorithm for planar mode propagation in arbitrary transmission lines
Authors: Ginsberg Jerry H.
Published: October 2011

Many textbooks treat the propagation of a harmonic plane wave in an acoustic transmission line. Their scope generally is limited to a small number of interconnected uniform cross section branches, and they emphasize fitting the propagation properties to continuity conditions at junctions. In contrast, the network formalisms advocated for intricate engineered systems, such as that offered fairly recently by Panigrahi and Munjal [J. Acoust. Soc. Am. 118, pp. 2860–2868], make them unsuitable for a first graduate-level course in acoustics. The present work offers an algorithmic approach that is simple to formulate, yet more efficient than available alternatives, and capable of treating arbitrary networks. The steps required to implement the algorithm are sequential numbering of the branch nodes and of the junctions, definition of a connectivity matrix that indicates which nodes are common to a junction, and statement of the continuity and termination conditions in terms of the port pressures and particle velocities. Beyond that the algorithm operates automatically. The result is a set of simultaneous equations for the complex pressure amplitudes at the junctions. In contrast, the approach offered by Panigrahi and Munjal derives simultaneous equations for the nodal pressures and port velocities, whose number is far greater than the number of junctions.
Demonstration of coupled membrane modes on a musical drum
Authors: Worland Randy
Published: October 2011

Musical drums such as tom toms and snare drums typically consist of two circular membranes attached to a cylindrical shell. Due to the enclosed air and the shell itself, a drum with two heads exhibits coupling of the lower frequency membrane modes, while the higher frequency modes of the two heads remain essentially independent. A simple demonstration has been developed that illustrates several aspects of drumhead vibrations, including the distinction between strongly and weakly coupled modes. Methods for determining the relative phases and amplitudes of the coupled oscillations have also been developed. The demonstration is useful at a variety of pedagogical levels and can be supplemented with more advanced experiments, including the use of electronic speckle pattern interferometry to identify the mode shapes on both membranes.
The octave illusion revisited: Performance measurements for handedness categorization
Authors: Oehler Michael , Reuter Christoph , Schandara Harald , Kecht Michael
Published: October 2011

An extended replication study of the octave illusion (Deutsch 1974, 1983) is presented. Since the first description of the octave illusion in 1974, several studies showed that the perception of the two-tone patterns depends on subjects' handedness. Partially almost 90% of the right-handed subjects reported to hear the high tone of the octave at the right ear. In all related studies the handedness categorization was done by means of a questionnaire, e.g., the handedness inventory of Varney and Benton (1975). Several current studies (e.g., Kopiez, Galley, Lehmann, 2010), however, showed that objective non-right-handed persons cannot be identified by handedness inventories. In concordance with Annett's “right shift theory” (2002), performance measurements as speed tapping seem to be a much more reliable handedness predictor. Therefore in the replication study (N=158) Varney and Benton's inventory as well as a speed tapping task were used to categorize left- and right-handed subjects. The results of Deutsch's study could be replicated when using the same handedness inventory. The performance measurement task, however, led to a significantly clearer distinction between the left- and right-handed subjects (w=0.39 in contrast to w=0.26 in the replication) and more structured perception patterns could be observed within the left-handed group.
Songs, cell phones, absolute pitch: Long-term pitch memory for familiar stimuli
Authors: Dooley Kevin
Published: October 2011

Absolute pitch (AP) is a rare phenomenon as formally defined, but long-term pitch memory appears much more common when tests involve familiar musical material and do not require the use of formally learned pitch labels. It is unclear whether AP possession confers additional advantages to long-term pitch memory in such tasks or merely combines a rare ability to form pitch-label associations with a more general capacity for pitch memory. To test this, 36 trained musicians—18 AP possessors and 18 non-possessors with equivalent age of onset and duration of musical training—were asked to recall and vocalize a familiar song, and their responses were compared with the pitches of the actual recordings; this was repeated with their cell phone ringtones. Both groups were significantly more accurate than chance on the song task, but only the AP possessors performed above chance on the ringtone task. The findings confirm the existence of widespread long-term pitch memory but also point to an AP advantage under some circumstances.
Methods for automating multichannel directivity measurements of musical instruments in an anechoic chamber
Authors: Eyring Nicholas J. , Leishman Timothy W. , Sorensen Kristina M. , Eyring Nathan G. W.
Published: October 2011

Comprehensive directivity measurements of musical instruments in anechoic environments involve several experimental challenges. However, by adapting methods currently used to characterize loudspeaker directivity (e.g., through high-resolution balloon plots), one can obtain highly detailed and instructive directivity data. This may be accomplished by rotating a musical instrument with sequential azimuthal angle increments under a fixed semicircular array of microphones while recording repeated notes or sequences of notes. The result is a computer-controlled acquisition of hundreds or even thousands of sound pressure measurements over a measurement sphere. The directivity data and corresponding balloon plots may be shown to vary as functions of time or frequency. This paper explores the approach applied to a grand piano with velocity controlled keys played through MIDI communication. Instruments played by live musicians may also be evaluated, although the process requires carefully developed techniques of control, feedback, and compensation to achieve acceptable results. These and other considerations of performing automated, multichannel directivity measurements of musical instruments are detailed in this presentation.
Propagation in a realistic outdoor environment
Authors: Coyle Whitney L. , Sparrow Victor W. , Ikelheimer Bruce , Downing Micah , James Michael , Bradley Kevin , Mellon Josh
Published: October 2011

A complementary experimental and computational study was conducted to assess variability in realistic outdoor sound propagation environments. Field measurements were conducted in a valley of the Smokey Mountains located in western North Carolina. This location exhibited complex terrain, vegetation, and weather conditions. Continuous and impulsive sources were positioned in multiple, reciprocal locations for the experiment. Receiver locations were spread throughout the area with many significant terrain features. Simultaneous atmospheric measurements were made to measure wind speed and temperature profiles and a level of turbulence. A Green's function parabolic equation model was written and used with matching conditions for comparison. This presentation will give a brief overview of the project and provide preliminary results. [Work supported by Spawar Systems Center Pacific.]
Model-data comparison for acoustic propagation over water
Authors: Pecknold Sean P. , Tollefsen Cristina , Murowinski Emma
Published: October 2011

Modeling the propagation of sound over water is an important tool for determining the possible effects of noise sources on the environment, such as naval gunfire exercises on bird nesting grounds, or offshore wind turbine disturbance. Temperature, humidity, and wind speed and direction all play an important role in determining acoustic propagation over water. Here, a sound source is mounted on a boat moving up to 2.5 km toward and away from a receiver on another vessel, over the span of several days. The propagation loss measured as a function of range is compared to modeled results based on measured temperature, humidity, wind velocity, and surface roughness, using atmospheric turbulence models to improve prediction capability.
Application of the equivalent source method to outdoor directional sound sources
Authors: Vecherin Sergey N. , Wilson D. Keith , Ostashev Vladimir E.
Published: October 2011

Many outdoor sound sources, such as aircraft and moving ground vehicles, exhibit directional sound radiation patterns that can be measured in the far field. However, this information is insufficient for specifying a source function that can be used in propagation algorithms. The equivalent source method (ESM) allows one to reconstruct an equivalent distribution of point sources having a given far-field radiation pattern. In this research, the application of the ESM to spatially complex radiation patterns, similar to those of actual helicopters, is studied in detail. Two algorithms for the source reconstruction are developed for arbitrarily complex radiation patterns. The first algorithm reconstructs three-dimensional source distributions that may not, however, be convenient for initializing calculations withparabolic equations. The second algorithm is designed for the two-dimensional parabolic equations and reconstructs strictly vertical source distributions having a given radiation pattern over a limited range of elevation angles. Some practical aspects of the measured data, such as outliers, data incompleteness, and phase loss in sound level measurements are also studied and recommendations are provided for mitigating their adverse effects on source reconstruction.
Picosecond ultrasonic microscopy of semiconductor nanostructures
Authors: Grimsley Thomas J. , Che Shan , Antonelli G. Andrew , Nurmikko Arto V. , Maris Humphrey J.
Published: October 2011

We describe a new picosecond ultrasonics method for the study of nanostructures. A sound pulse is generated when an ultra-short laser pulse is absorbed in a transducer structure. The sound then propagates across a thin layer of water and is reflected from the surface of the sample being examined. A resonant optical cavity is used to improve the efficiency of optoacoustic detection and generation of the sound. We report on experiments in which sound is reflected from patterned nanostructures. In these experiments, we are able to study the propagation of sound down channels of width as small as 35 nm.
Using light to probe hypersound in porous materials systems
Authors: Parsons Lance C. , Peckham Jordan , Polomska Anna M. , Andrews G. Todd
Published: October 2011

An overview of the technique of Brillouin light scattering spectroscopy and its application to the study of hypersound in micro- and mesoporous materials systems will be presented. Particular emphasis will be placed on results obtained from light scattering experiments on porous silicon-based structures. For porous silicon films, it was found that the acoustic phonon velocities and elastic properties depend strongly on the film porosity and morphology. Brillouin studies of porous silicon superlattices with periodicity on the order of the hypersound wavelength reveal that these structures behave as hypersonic phononic crystals, while those with smaller modulation wavelengths act as effective elastic media. New results on localized acoustic modes in porous silicon multilayers will also be discussed. Collectively, these studies provide a detailed picture of hypersound propagation in porous silicon systems and demonstrate the utility of Brillouin spectroscopy for probing acoustic phonon behavior in this challenging class of materials. [This work was supported by the Canada Foundation for Innovation, Memorial University of Newfoundland, and the Natural Sciences and Engineering Research Council of Canada.]
A holey structured acoustic metamaterial
Authors: Zhu J. , Christensen J. , Jung J. , Martin-Moreno L. , Yin X. , Fok L. , Zhang X. , Garcia-Vidal F. J.
Published: October 2011

The resolution of acoustic imaging system is restricted by diffraction limit. To beat this limit, early research shows acoustic metamaterials that can manipulate acoustic waves artificially and may act as lens to achieve subwavelength resolution. However, these solutions suffer significant loss therefore lack convincing experimental demonstration. Recent study suggested that arrays of metallic nanorods or nanowire can be used as lens for optical imaging at subwavelength resolution. Similar acoustic hyperlens designs have also been explored, and latest experimental result provided resolution of wavelength/7. Here presented is a holey structured endoscope which supports the transmission of the otherwise-evanescent waves over distances, therefore beating diffraction limit and achieving deep subwavelength imaging. Experimental demonstration shows clear image with feature size of wavelength/50. Such a metamaterial endoscope brings new perspectives to the applications of medical ultrasonography, sonar and ultrasonic non-destructive evaluation.
A study of the nonlinear effects of air bubbles on the ultrasonic field in water
Authors: Vanhille Christian , Campos-Pozuelo Cleofé
Published: October 2011

We consider the propagation of ultrasonic waves in water with air bubbles. On the one hand, a numerical model has been developed to analyze the nonlinear effects of the bubbles at high amplitude, in several configurations (open-field, standing waves, 1–D, 2–D, 3–D, homogeneous bubble density, bubble layers, bubble clouds, bubble generation). On the other hand an experimental setup has been constructed and allows us to study the nonlinear behavior of the inertial cavitation field at high frequency and at high power. In particular, a bubble cloud is formed at a large distance from the sonotrode. [Work is part of the research project DPI2008-01429 funded by the Spanish Ministry of Science and Innovation.]
Dynamics of bubble clusters in acoustic field
Authors: Akhatov I. S. , Nasibullaeva E. S , Volkova Y. V. , Gumerov N. A.
Published: October 2011

A bubble cluster composed of gas bubbles of various radii oscillating in an unbounded, slightly compressible viscous liquid under the action of an external acoustic field is considered. The mathematical model describing the dynamics of this bubble cluster is presented. The proposed model is used for an analytical study of small (linear) bubble oscillations in monodisperse and polydisperse clusters, for a numerical investigation of large (nonlinear) bubble oscillations, and for a diffusion stability analysis of gas bubbles in the cluster. The following phenomena have been revealed: (1) synchronization of the collapse phases of bubbles with different radii and (2) collapse intensification for bubbles of one size in the presence of bubbles of other size. These effects are explained by the interaction between bubbles of different radii in the cluster. For a monodisperse (one-fraction) cluster, numerical values were obtained for the initial gas concentrations in the liquid at which bubbles tend to one of two equilibrium states due to the rectified diffusion. It is also found that a polydisperse (two fraction) cluster tends to become a one fraction cluster due to the rectified diffusion. [This research is supported by the Grant of the Ministry of Education and Science of the Russian Federation (G34.31.0040).]
Radiation efficiency, impedance, and the acoustics of rattle
Authors: Shorter Philip , Cotoni Vincent , Langley Robin
Published: October 2011

Rattle issues consistently rank as one of the top consumer complaints in initial quality surveys for many new products. Predicting the acoustics of rattle is complicated by the need to model the vibro-acoustic response of large complex structures across a broad frequency range. The complexity of the analysis can be reduced by making use of standard methods derived almost 50 years ago. In particular, this paper discusses a computationally efficient method for assessing the propensity for rattle in large complex structures. A finite element model is used to predict the probability that impacts will occur when a product is exposed to a particular low frequency random vibro-acoustic environment. The expected contact forces arising from each impact are then estimated by making use of expressions involving the drive point impedances of infinite structures. Finally, the vibration and acoustic radiation associated with the various impacts are predicted and ranked using a SEA model. A number of examples are presented including one which makes use of a radiation efficiency formula due to G. Maidanik. The results are in very good agreement with analytical reference results.
Fuzzy structures applied to a vibrating beam
Authors: Feit David
Published: October 2011

Gideon and I were both introduced to the ideas of “Fuzzy Structure Theory” during a visit with Christian Soize while involved in an exchange meeting between the U.S. Navy and the French Navy in 1986. In the years just prior to his passing, he together with Ron Hughes pursued this subject, and that work is also presented in this session. My presentation, a continuation of work that I had originally done with Murray Strasberg, discusses the transient response of a multiple set of fuzzy structures attached to a master structure, either a longitudinally or flexurally vibrating beam, that itself has multiple resonances. The transient response of the subordinate oscillators in certain parameter ranges gives rise to distinct packets of energy traveling with different wave speeds. This phenomenon has not been previously observed, and a tentative explanation is offered.
Estimating uncertainty in inverse elasticity with application to quantitative elastography
Authors: Barbone Paul E. , Chue Bryan , Oberai Assad A.
Published: October 2011

We consider an inverse elasticity problem motivated by medical ultrasound imaging: Given a displacement field measured in a 2D domain, determine the modulus distribution in that domain. An iterative approach to solve the inverse problem can be formulated by repeated solutions of the forward problem. That is, the shear modulus distribution sought is that which predicts a displacement field most consistent with the measured displacement field and any assumed a priori knowledge of the modulus distribution. All such inverse problem solutions are subject to uncertainties in the data, however, which results in uncertainties in the predictions. For diagnostic purposes, it is desirable to know the confidence intervals within which the stiffness at a point might reside. The focus of this presentation is the computation of said confidence intervals. We discuss the formulation of the problem within a Bayesian context. We derive a formal solution for the a posteriori probability distribution of the modulus. We prove bounds on uncertainty in terms of the data at the continuous level and discuss the computational solution of the problem at the discrete level.
Wave approach for the resonances of irregular polygonal membranes
Authors: Dickey Joseph
Published: October 2011

This study develops a wave or ray technique for determining the resonance frequencies of irregular polygonal membranes. The technique is demonstrated for homogeneous, isotropic, rectangular, and triangular membranes with fixed, free, and mixed boundaries. Where possible, the results are compared with exact calculations. The membrane resonances are calculated using an equivalent string whose length is proportional to the reciprocal of the length of closed paths starting from an arbitrary point within the membrane. Closed paths are ray paths which arrive back at the starting point going in the same direction. The extension of the technique to other irregular polygons and the relationship of the resonance determination in determining the response of the membranes to point excitation are discussed.
Semi-supervised learning for speech and audio processing
Authors: Hasegawa-Johnson Mark A. , Huang Jui-Ting , Zhuang Xiaodan
Published: October 2011

Semi-supervised learning requires one to make assumptions about the data. This talk will discuss two different assumptions, and algorithms that instantiate those assumptions, for the tasks of acoustic modeling and pronunciation modeling in automatic speech recognition. First, the acoustic spectra corresponding to different phonemes overlap, but there is a tendency for the instantiations of each phoneme to cluster within a well-defined region of the feature space—-a sort of “soft compactness” assumption. Softly compact distributions can be learned by an algorithm that encourages compactness without strictly requiring it, e.g., by maximizing likelihood of the unlabeled data, or even better, by minimizing its conditional class entropy. Second, the observed phone strings corresponding to coarticulated pronunciations of different words are also, often, indistinguishable, but can be transformed into a representation in which the degree of overlap is substantially reduced. The canonical phonetic pronunciations are transformed into an articulatory domain, possible mispronunciations are predicted based on a compactness criterion in the articulatory domain, and the result is transformed back into the phonetic domain, forming a finite state transducer that is able to effectively use hundreds of alternate pronunciations.
Dealing with unknown unknowns in speech
Authors: Hermansky Hynek
Published: October 2011

Common belief in speech recognition community is that most significant improvements in performance on a machine come from more training data. Implicit is a tacit assumption that speech to be recognized comes from the same distribution as the speech on which the machine was trained. Problems occur when this assumption is violated. Words that are not in a lexicon of a machine, unexpected distortions of a signal and noises, unknown accents, and other speech peculiarities all create problems for the current ASR. The problem is inherent to machine learning and will not go away unless alternatives to extensive reliance on false beliefs of unchanging world are found. In an automatic recognition of speech, words that are not in the expected lexicon of the machine are typically substituted by some acoustically similar but nevertheless wrong words. Similarly, unexpected noise is typically ignored in human speech communication but causes significant problems to a machine. We discuss a biologically inspired multistream architecture of a speech recognition machine that could alleviate some of the problems with the unexpected acoustic inputs. Some published experimental results are given.
Deep brain stimulation in Parkinson's disease: The basics
Authors: Verhagen Leo
Published: October 2011

Parkinson's disease (PD) affects over 1 × 106 people in the United States with 50 000 Americans being diagnosed each year. As a neurodegenerative movement disorder, it affects patients' lives through its slow but relentless progression of both motor and non-motor symptoms. Initially, most PD patients receive good benefit from dopaminergic treatment, but over time the symptomatology changes. The goal of this presentation is to discuss the motor features of advanced PD. Treatment of advanced PD typically consists of a combination of pharmaceuticals, but in recent years deep brain stimulation has been increasingly used to complement medical therapy. DBS for PD is indicated in some patients while it may not be the best treatment option for others. Selection criteria, indications, and relative contraindications will be discussed. The procedure will be reviewed and an overview of recent outcomes of DBS studies in PD will be provided. Attention will also be given to potential side effects of this state of the art treatment. Throughout the presentation, video clips will highlight the phenomenology under discussion.
Effect of deep brain stimulation on speech in Parkinson's disease: From research lab to clinic
Authors: Wang Emily
Published: October 2011

Bilateral deep brain stimulation (DBS) of the subthalamic nucleus (STN), an evidence-based, effective surgical treatment with increasing popularity, can help patients with advanced Parkinson's disease eliminate or lessen many of the motor symptoms they experience. However, one of its unfortunate adverse effects is that it may worsen existing speech impairment as well as causing new impairment. As a result, the patients may be unable to speak loudly or clearly, or simply unable to initiate speech. The problems often associate with active as well as chronic STN stimulation. Further, there does not seem to be a uniform effect on different speech subsystems of respiration, phonation, and articulation. In this presentation, we will first review studies which have shown differential effects on phonation, articulation, and prosody associated with unilateral vs. bilateral STN DBS. Next, we will discuss the preliminary outcomes of several potential treatment approaches and strategies including the Lee Silverman voice treatment, change of DBS settings, and the altered auditory feedback. Lastly, we will discuss our experience of using the approaches and strategies helping patients with their speech deficits associated with STN DBS in clinical settings. Both mechanisms and limitations will be explored.
Differential effects of deep brain stimulation (DBS) on speech and limb movements in Parkinson's Disease (PD): Clues to basic mechanisms
Authors: Poizner Howard
Published: October 2011

A puzzling finding has been that STN DBS improves limb motor function, while at the same time providing little benefit to or even markedly worsening speech. In collaboration with Peter Fox's Research Imaging Institute in San Antonio, we combined objective measures of speech with PET imaging and TMS in a PD patient with speech deficits due to STN DBS. Stimulating the left STN produced deteriorated speech together with hyperactivation of left dorsal premotor cortex (PMd), an area known to project to the left STN. TMS to left PMd with DBS off, produced similar speech impairments as DBS stimulation. These findings are consistent with STN DBS antidromically disrupting left PMd activity, thereby causing speech deterioration. In contrast, STN DBS is known to improve limb motor control. We have been examining the effects of STN DBS on reaching to and grasping objects, on reaching to kinesthetically defined 3-D targets, and on inhibiting a pre-programmed action. We have found that bilateral STN DBS improves all of these behaviors, although to varying degrees. Moreover, EEG recordings during response inhibition suggested that the physiological mechanism for the improved behavioral control involves normalization of brain rhythms that may be involved in transferring information within cortico-basal ganglia circuits. [Work supported in part by NIH grant #2 R01 NS036449 and ONR MURI Award No.: N00014-10-1-0072.]
Acoustic diver deterrent in a shallow harbor using time reversal acoustics
Authors: Sutin Alexander , Sinelnikov Yegor
Published: October 2011

Protection of domestic harbors against surface and underwater threats is an important task of port security. A significant security risk is associated with scuba divers ability to carry explosives. The diver detection sonars have been developed and there is a need to compliment it with low cost acoustic swimmer deterrent. Previous research demonstrated that time reversal acoustic (TRA) system can focus intensive sound using acoustic noise from a diver. This paper discusses the feasibility of applying TRA principles for the focusing of sonar ping-pulse reflected from a diver. The advantages of the TRA focusing system and relevant operating parameters are demonstrated using the model of shallow sea, where propagation of sonar pulse is affected by numerous reflections from surface and bottom. The developed model was used to estimate and compare an effective zone of the diver deterrence taking into consideration the sonar pulse reflections from diver, bottom and surface. The main objective was to estimate if NAVY ship sonar is capable of producing sufficient and spatially localized sound pressure to disorient and divert the diver away. A secondary objective was to ensure that sound pressure level outside the focal zone in the diver proximity remains not harmful to marine life.
A multi-beam array technique for acoustical imaging
Authors: Brady John F. , Sinha Dipen N.
Published: October 2011

Most acoustical imaging systems rely on phase-steered or multiplexed transducer arrays, requiring complex electronics and powerful data acquisition. This presentation discusses a 1-D array capable of generating multiple simultaneous directional beams in both transmit and receive modes. The array can image over a 50 deg window in a single pulse-echo cycle while requiring as few as four electronic channels for operation. The advantages of this simple approach compared to techniques previously mentioned will be discussed.
Relating volume scattering from the seafloor to dispersion and attenuation within the seafloor
Authors: Hefner Brian T.
Published: October 2011

Heterogeneities in ocean sediments can produce significant scattering of sound from the seafloor, particularly in soft sediments. First-order volume perturbation models for scattering from the seafloor into the water ignore the effect of this scattering on propagation and dispersion within the sediment. The energy that is scattered, however, contributes to the attenuation of the penetrating sound. This increase in attenuation, and its effect on dispersion, is modeled by applying perturbation theory to sound propagation through a fluid sediment. This allows the application and predictions of this propagation model to be connected directly to previous perturbation approximations of scattering from the sediment. Several sediments for which volume scattering has been previously studied are revisited in the context of sound propagation. The implications of this loss mechanism within the sediment for the scattering of sound from the sediment are also considered. [Work supported by the Office of Naval Research.]
Initial assessment of combustive sound source arrays as airgun alternatives for Arctic under-ice seismic exploration
Authors: Arvelo Juan I. , Dietz Jerrold , McNeese Andrew R. , Sagers Jason D. , Wilson Preston S.
Published: October 2011

Combustive sound source arrays consisting of submersible combustion chambers filled with a hydrogen/oxygen mixture are employed to assess their effectiveness for seismic exploration applications. The combustive mixture is ignited via spark and radiates acoustic pulses capable of undersea deep sub-bottom sediment penetration. Since electrolytic cells may be employed to generate the hydrogen/oxygen mixture from surrounding seawater, this source is an attractive alternative to airgun arrays for Arctic seismic exploration from under-ice platforms. Combustive sound source array configurations were tested in a central Virginia basin with hydrophones deployed in a line at another nearby basin. Seismic reflections are compared against nearby geologic cross sections of the central Virginia seismic zone. [Funding provided via UAF sub-award under NOAA Grant NA09NOS4000262 and ONR.]
Seismic tremor event intervals from dual-frequency coherence
Authors: Dorman LeRoy M. , Schwartz Susan Y. , Tryon Michael
Published: October 2011

Slip occurring at plate boundaries creates seismic tremor as well as “normal” earthquakes. This nonvolcanic tremor appears to consist of swarms of low-frequency earthquakes which lack impulsive P and S arrivals. Tremor is accompanied by slip observed by GPS and can show anomalies in fluid flow. The seismic radiation resembles continuous microseismic noise more than discrete events. We report dual-frequency coherence (DFC) calculations on tremor and normal microseismic background noise observed on Ocean-Bottom Seismographs and land seismic stations around the Nicoya Peninsula, Costa Rica. Both the OBS and land tremor signals show a banded pattern in DFC that is absent in normal noise. The similarity in the DFC patterns between OBS and land tremor signals suggests a common source, eliminating the possibility that DFC is a property of the OBS or seafloor environment. Banded DFC patterns can be generated by repeated events with a repeat time equal to the reciprocal of the offset frequency between bands. If, as is becoming widely accepted, nonvolcanic tremor consists of swarms of low frequency earthquakes (LFEs), DFC analysis may help to reveal LFE periodicities or intervals.
Using a spherical microphone array to analyze concert stage acoustics
Authors: Caulkins Terence , Guthrie Anne , Clapp Sam , Braasch Jonas , Xiang Ning
Published: October 2011

A 16 channel spherical microphone array has been designed and constructed to measure high order Ambisonic sound fields, based on equations for scattering off of a rigid sphere. This microphone has been used to capture and characterize the acoustics of nine different concert hall stages around the state of New York. Musicians have been invited to perform in real-time in auralizations of each hall and participate in a subjective preference test based on their experience. The preference tests have been analyzed using multi-dimensional scaling methods and compared with acoustical data derived from a beamforming analysis of each stage. Additional comparisons with A.C. Gade's omnidirectional parameters (stage support, early ensemble level) and geometric parameters described by J. Dammerud are performed.
Acoustical renovation of Hahn Recital Hall at the Music Academy of the West, Montecito, CA
Authors: Chu William , Conant David A.
Published: October 2011

A 350-seat fixed-acoustics recital hall believed designed by Vern Knudsen in 1971 was substantially renovated in 2008 to meet the current needs of the revered Music Academy of the West. The preponderance of its program was to serve Marilyn Horne's operatic program as well as chamber music but required as well to provide suitable space for occasional full orchestra rehearsals and performance. The renovation design is described as it developed from initial acoustical measurements to the novel platform acoustics and other adjustments that permit optimizing the large platform for multiple needs. Specifics of the acoustical coupling characteristics of the custom, sound transparent/sound reflective and diffusive recital screen, its overhead reflectors and absorptive drapery are discussed as well as accommodation for Met Live presentations.
Automatically identifying rare sounds of interest in environments cluttered with biological homophones
Authors: Fristrup Kurt M.
Published: October 2011

Successful acoustical monitoring for threatened or endangered species must surmount challenges of adequate spatial and temporal coverage in the data collection phase, and efficient and effective processing in the data analysis phase. For terrestrial environments, a diverse array of digital recording options has relaxed the difficulty of obtaining sufficient coverage. However, this capability has amplified the requirement for efficient processing. In many terrestrial environments, the principal processing challenge is distinguishing the sounds of rare species from many other sounds that are similar in time-frequency structure. Some of these biological homophones are generated by species that are much more numerous than the target. Solutions to these problems will be assessed in the context of large scale projects that focused on bird species of special interest.
Acoustic detection of the Ivory-billed Woodpecker (Campephilus principalis)
Authors: Collins Michael D.
Published: October 2011

There have recently been independent reports of multiple sightings and auditory detections of the Ivory-billed Woodpecker (Campephilus principalis) in remote swamps in Arkansas, Florida, and Louisiana. Putative audio and video recordings have been obtained at each site, but no clear image of this critically endangered (and extremely elusive) species has been obtained in decades. Acoustic detection is possible by “kent” calls, alarm calls, double knocks, and pounding sounds associated with foraging and cavity construction, but each of these clues is problematic. Kents are difficult to hear in the distance—the author did not detect a long series of kents before drifting in a kayak to well within 100 m of the bird. This species does not drum like other woodpeckers, and it is believed to forage relatively quiet (at least part of the time) by using its massive bill to pry bark loose. The Ivory-billed Woodpecker is not one of those species that is easier heard than seen—during 5 yr of fieldwork, the author had ten definite sightings but only two definite auditory detections. These issues and the current status of the fieldwork in the Pearl River basin in Louisiana will be discussed.
Interannual temporal and spatial distribution of bowhead whales in the Western Alaskan Beaufort Sea; 2007–2010
Authors: Grassia Stephanie L. , Berchok Catherine L. , Wright Dana L.
Published: October 2011

Passive acoustic monitoring began offshore of Barrow, Alaska, in 2007 as part of the interdisciplinary BOWFEST (Bowhead Feeding Ecology Study) project. This study area spans from the northern coast of Alaska out to 72°N and between 152° and 157°W. To better understand how bowhead whales use this area, long-term (year-long) and shorter-term (week- to month-long) autonomous passive acoustic recorders were deployed on subsurface moorings. The long-term recorders were deployed at four locations along the 100 m isobath off Barrow, running on a 30%–45% duty cycle at a sampling rate of 8192 Hz. The shorter-term recorders were deployed inshore (<20 m water depth) and sampled at either 12.5 or 40 kHz on a 80%–90% duty cycle (although one sampled continuously at 8192 Hz). Since 2007 we have obtained 18 820 h of recordings from the long-term and 3780 h of recordings from the short-term moorings. All recordings were reviewed manually, with the long-term data analyzed on a 3-h time interval and short-term data analyzed fully. The majority of the bowhead call detections were between April and November. Very few detections were made during the winter months. Comparisons between the offshore recorders and inshore recorders (which were within the main migration corridor) will be discussed.
Passive acoustic monitoring of North Atlantic right whales in Cape Cod Bay
Authors: Lin Ying-Tsong , Newhall Arthur E. , Baumgartner Mark F.
Published: October 2011

Passive acoustic techniques have been applied extensively to marine mammal monitoring, localization, and tracking. An acoustic fieldwork using hydrophone arrays and free-floating buoys was conducted in Cape Cod Bay in the spring of 2011 for monitoring North Atlantic right whales. Three vertical hydrophone arrays were deployed to form a large triangular network with approximately 12 km on each side, and one horizontal array was mounted on the seafloor at one station. The passive hydrophone arrays operated for 25 days and recorded a vast amount of vocalizations made by humpback, fin, sei, minke, and, most importantly, right whales. These data can be used for localizing these endangered animals and tracking their movements in the bay with a large spatial coverage. Acoustic buoys, the real-time acoustic tracking system, were deployed on two one-day cruises for several hours at a time to triangulate calling whales over small spatial scales, and can be used to ground truth long-range whale localizations derived from the array network. Results from different passive acoustic techniques will be presented and compared. [Work supported by the Ocean Life Institute and the Marine Mammal Center of the Woods Hole Oceanographic Institution.]