bluuebunny/crossref_metadata_2025 huggingface dataset:
Distributed detection and estimation based on the turbo approach.
Authors: Roan Michael , Hoppe Elizabeth
Published: October 2013

We develop a centralized information fusion architecture from basic principles of information theory and Bayesian statistics. It is well known that any clustering, quantizing, or thresholding of data causes loss of information unless a sufficient statistic is computed in the processing. For the case of wideband active ranging systems, the coherent output of an optimum beamformer and a matched filter is a sufficient statistic that can be transmitted to the fusion center. For unknown target velocity, range, and bearing, the wideband space-time matched filter output can be interpreted as a multidimensional wavelet transform or a delay-scale-bearing map. In this paper, an iterative, Bayesian, joint estimation-detection approach is used for computation of sufficient statistics and multisensor information fusion. An approach borrowed from sequential Bayesian processing is used to compute prior densities for joint Bayesian estimation-detection. In this approach a posteriori densities become priors after a coordinate transformation that transforms the outputs of each sensor to a common reference frame for all sensors. In this paper, receiver operating characteristics and Cramer–Rao lower bounds are given for several undersea signal processing cases of interest.
Variational Bayesian particle filtering for underwater target localization and tracking.
Authors: Brandes T. Scott , Dasgupta Nilanjan , Carin Lawrence
Published: October 2013

Kalman filtering methods used in target tracking applications fail to perform satisfactorily when the true underlying posterior density of a target’s location is non-Gaussian. These circumstances arise often in highly noisy environments dominated by strong scattering returns from clutter. Advanced tracking approaches, such as particle filters (PFs), that do not have the linear and Gaussian requirements of Kalman filtering are needed for target tracking in those complex environments. We used a variational Bayesian (VB) particle filter in our research to accurately track underwater targets simulated for such regimes. Particle filters rely on a Monte Carlo method of approximating the posterior distribution of an underwater moving target’s location by a weighted set of sample points (particles) that evolve in time with the target. Variational Bayesian inference uses a Monte Carlo approach to estimate a distribution of the parameters of the posterior through a series of converging approximations. Our VB approach is shown to outperform the standard PF in both an active system (target tracking) and a passive system (source localization) in simulations.
The dependence of the intensity of surface scattered signals on surface wave characteristics.
Authors: Preisig James , Deane Grant , Tindle Chris
Published: October 2013

The compensation for the fluctuations in surface scattered signals remains one of the challenges for reliable and high rate underwater acoustic communications systems. Communication using phase coherent signals relies on the ability of the receiver to track the fluctuations in the impulse response of the channel between the transmitter and receiver. Techniques that can exploit a priori statistical characterizations of the fluctuations of the arrivals in the channel impulse response (fading statistics) will generally outperform systems that do not have access to such information. While fading statistics in radio communications is generally assumed to be Rayleigh or Rician, prior work [J. C. Preisig and G. B. Deane, J. Acoust. Soc. Am. 116, 2067–2080 (2004)] has shown that surface wave focusing can significantly change channel fading statistics. The physical basis for the intensity of surface scattered signals for both isolated specular scattering points and caustics developed in [C. T. Tindle and G. B. Deane, J. Acoust. Soc. Am. 117, 2783–2794 (2005)] relates intensity to ray geometry parameters. In this work, surface wave characteristics are related to both the source to receiver ranges at which normal focused specular scattering and caustics will occur and to the intensities of the surface scattered arrivals in each case. Experimental data are presented comparing theoretically predicted and measured intensities.
Coherent communications performance in environments with strong multi-pathing: Model/data comparison.
Authors: Rouseff Daniel
Published: October 2013

Coherent underwater communications is hampered by the time spread caused by multi-pathing and the Doppler spread caused by the rapidly changing shallow water environment. In practice, a time-varying impulse response model will retain only a finite number of paths as useful signal and will be updated to compensate for the changing environment at a finite rate. In the present study, communications performance is examined as a function of the number of retained paths and the model-update interval. Results are quantified in terms of the mean squared error in the soft demodulation output. A physics-based performance model is developed. The model uses as input acoustic quantities like the Rayleigh parameter and environmental quantities like the significant wave height and the dominant period for surface waves. Model predictions for performance are compared to experimental results for data collected near the Hawaiian Island of Kauai. [Work supported by ONR.]
Ocean variability effects on high-frequency coherent acoustic communications.
Authors: Song Aijun , Badiey Mohsen , Song H. C. , Hodgkiss William
Published: October 2013

The variability of the ocean environment can cause fluctuations of acoustic channels and these fluctuations often pose serious difficulties for high rate digital communications. During a series of recent acoustic communications experiments conducted around Kauai Island, Hawaii (KauaiEx’03, MakaiEx’05, and KAM’08), coherent communication data with concurrent environmental measurements were collected under different experimental settings. The variability of the ocean parameters, mainly the water temperature profiles and the sea surface condition, has been studied in order to understand their impact on the performance of acoustic communications at high frequencies (greater than 10 kHz). It is shown that both the long-term (in hours) changes in the ocean volume and the fast fluctuations (in seconds) of the sea surface have impact on the receiver design and on the receiver performance. Using time reversal combining followed by a single channel decision feedback equalizer, the ocean variability effects on the performance of coherent acoustic communications are shown as a function of receiver depth, source depth, and communication range.
Improving underwater vehicle communication in the littoral zone through adaptive vehicle motion.
Authors: Schneider Toby E. , Schmidt Henrik
Published: October 2013

Autonomous underwater vehicles (AUVs) are increasingly being used in clusters to perform detecting and sensing tasks in the littoral zone. These tasks require substantial data throughput between underwater and surface nodes. Acoustic modems provide the only practical means of sending these data, but sound in the littoral waveguide is heavily refracted downward and multiply reflected by the shallow bottom. These effects lead to shadow zones where messages are lost and convergence zones that allow for longer range receipt of high bitrate messages. During the GLINT08 sea trials, messages were sent using a multiple rate 25-kHz acoustic modem (the WHOI “MicroModem”) between several undersea and surface nodes. The message quality (mean square error) was analyzed and compared to dynamic ray tracing models of the transmission loss, using environmental data measured by the AUVs and the research vessel. Significant correlation was found between the data and the modeled acoustic field, suggesting that such models could be run on-board the AUVs to predict regions of low transmission loss. This would give the AUVs predictive ability to choose when to send messages to maximize the probability of receipt and the choice adaptively move to improve chances of successful message reception.
Comparison of modeled versus measured room acoustic parameters in the recently completed Shaghoian Concert Hall in Clovis, California.
Authors: Dohn Bill , Campbell Richard H.
Published: October 2013

The Shaghoian Concert Hall in Clovis, CA is a popular new variable acoustic music venue in the greater Fresno, CA area. The design process for this hall included CATT-Acoustic (TM) modeling for analysis and verification of essential room acoustic parameters based upon the settings of the variable acoustic devices. The model of the final design produced parameters that were closely in line with ideal values for a hall of this size and use. Model results will be compared to measured parameters in the completed hall.
Comparison of auralized and measured sound in moderately reverberant spaces.
Authors: Coffeen Robert C. , Birney Jonathan , Hoeman Stephanie , Kanter Shane , Schultheis Hannah , Ronsse Lauren M. , Wang Lily M.
Published: October 2013

This research performs an in-depth comparison of sound from computer auralizations with measured binaural room impulse responses and recordings taken in actual spaces. Binaural measurements and recordings have been gathered in two church naves with midfrequency reverberation times of about 1.5 and 2.5 s. The results from these measurements are compared with auralizations from computer models of the spaces in two different room acoustic modeling programs. The source and receiver positions used for the auralizations are the same as those measured in the real spaces. One of the naves was previously investigated [R.C. Coffeen and G. Caunt, J. Acoust. Soc. Am. 105, 1174 (1999) (A)] with results from computer auralizations compared to measured binaural recordings in the space. As numerous advancements have been made to computer modeling programs since that time, this project revisits and expands the previous research using updated modeling and measurement techniques. The results of this research not only portray the developments in computer modeling that have occurred over the past decade, but also depict the relationship between current computer auralizations and actual sound in moderately reverberant spaces.
Tracking fin and blue whales above the Juan de Fuca Ridge with a local seafloor seismic network.
Authors: Wilcock William S. D. , Soule Dax C. , Thomson Richard E.
Published: October 2013

The Endeavour segment of the Juan de Fuca mid-ocean ridge hosts several high-temperature hydrothermal fields. Previous analysis of bio-acoustical data shows that zooplankton are enhanced at all depths above the hydrothermal vent fields compared with sites ⩾10 km away. From 2003–2006, a seafloor seismic network was deployed around the hydrothermal vent fields to monitor earthquakes and it also recorded an extensive data set of fin and blue whale calls. As part of an investigation of a potential correlation between whale tracks, enhanced zooplankton concentrations, and hydrothermal vents above the Juan de Fuca Ridge, an automatic algorithm is being developed to track vocalizing whales that swim near the network. Events are detected by triggering with the ratio of short-term to long-term running RMS averages and whale calls are distinguished from earthquakes based on their spectra. For fin whales each 1-s arrival is identified based on its instantaneous amplitude and frequency and a pick is made at the mid-energy point. A grid search method is used to localize calls using direct and multipath arrivals. The algorithm and preliminary results will be presented. [The Keck Foundation supported the seismic network and the Office of Naval Research is supporting this study.]
The Acousonde: A miniature autonomous wideband recorder.
Authors: Burgess William C.
Published: October 2013

The Acousonde™ is a newly designed miniature acoustic/ultrasonic recording tag incorporating several improvements over its predecessor, the Bioacoustic Probe. Design trade-offs for its acoustic data paths targeted acquisition of both near and distant odontocete echolocation clicks with minimal distortion while preserving general-purpose utility and low-power operation. Two acoustic channels are available: a low-power channel for long-term recording of signals up to 9 kHz and a high-frequency channel for signals up to 100 kHz. Each channel has its own dedicated hydrophone. For antialiasing, the low-power channel uses an adjustable switched-capacitor elliptic filter, while the high-frequency channel uses a fixed-frequency linear-phase filter; both filters may be bypassed if raw acquisition is desired. “Ping-pong” alternating sampling may be used to acquire samples from both channels concurrently, possibly to assess time-of-arrival differences between the two hydrophones. The controlling microprocessor, an ARM 9 with vector floating point accelerator, can digitally filter and downsample acoustic data during acquisition to reduce storage requirements. Other sensors include a 3D accelerometer, a 3D compass, a depth transducer, and a temperature monitor. Eight gigabytes of data storage are available, with data offload via a MicroUSB connector. Initial tests with captive animals are planned shortly. [Work supported by ONR.]
Validated reef fish sound scans of passive acoustic monitors on Hawaiian coral reefs.
Authors: Tricas Timothy C. , Boyle Kelly
Published: October 2013

Monitoring of fish sounds on coral reefs is a valuable potential technique for fisheries managers to remotely assess local fish populations and their behaviors. However, the species identity of most fish sounds on shallow coral reefs is not known. We have deployed two ecological acoustic recorders (EARs) at 20 m deep on two shallow reefs on the island of Hawaii. In order to validate which fish species produce these acoustic behaviors we used closed circuit rebreather diving, which produces almost no ambient acoustic noise, to record video and sonic behaviors of fish near the recording sites. From the videos we have identified 37 putative acoustic species many of which produce multiple sounds that include behaviors associated with intra- and interspecific aggression, feeding, courtship, and spawning. Cluster analysis was used to identify acoustic clades among and within species. Acoustic waveform average templates were constructed for different species clades and used in XBAT to screen the long-term recordings from the EAR. The use of these species-specific sound templates confirms the potential to detect diel, lunar, and longer-term rhythmicity for several species. This technique also shows promise for characterizing seasonal and annual periods of activity of sounds associated with context-specific behaviors.
Beaked whale density estimation from single hydrophones by means of propagation modeling.
Authors: Küsel Elizabeth T. , Mellinger David , Thomas Len , Marques Tiago A. , Moretti David J. , Ward Jessica
Published: October 2013

Passive acoustic sonar systems offer many advantages to the study of marine mammals. For density estimation studies, it is important to evaluate the probability of detecting an animal as a function of its distance from the receiving sensor. In this work, acoustic propagation modeling is used to estimate the transmission loss as a function of depth and range between a source whale and a single-hydrophone receiver. The computed transmission loss is compared to ambient noise levels and source level distributions to estimate the detection probability as a function of range. Results will be compared to beaked whale data recorded on bottom-mounted sensors in the Atlantic Undersea Test and Evaluation Center (AUTEC) in the Bahamas, where the location of clicks is relative to one hydrophone. Source level and beam pattern extracted from digital acoustic tags (DTags) applied to a sample of animals at the same location will also be used in the detection model, and beaked whale spatial density will be estimated. The detection probability function will provide a relevant comparison to the detection function derived empirically from the DTag data by Marques et al. [Marques et al., J. Acoust. Soc. Am. (submitted).]
Phase front fluctuations due to internal waves in shallow water 2006 experiment.
Authors: Katsnelson Boris , Badiey Mohsen , Luo Jing , Lynch James
Published: October 2013

Experimental results and theoretical analysis of the sound phase front fluctuations measured by Vertical and Horizontal Line (VHLA) array (or L-shaped array) are presented. Low frequency broadband signals were radiated by the source (Miami Sound Machine) placed at the distance of ∼25 km from the VHLA. During the time period 18:00–22:00 GMT on Aug. 17, 2006, a train of internal solitons traveled across the acoustic track and initiated fluctuations of the sound field. In an earlier paper [J. Acoust. Soc. Am. 124, EL66–EL72 (2008)], it was shown that intensity of these fluctuations results from the horizontal refraction of the sound waves due to internal solitons. Here we show the acoustic phase front fluctuations for separate waveguide modes for the same period. To obtain phase fronts for the individual modes, a special approach using an L-shaped receiver array is used. The vertical part of the array was used to obtain modal amplitudes. Using the measured sound field based on the perturbation theory, modal phases at the HLA can be calculated. Results of data processing are compared with theoretical calculations. [Work supported by ONR, CRDF, and RFBR.]
Signal intensity fluctuations in Shallow Water 2006 (SW06) experiment during Event 50.
Authors: Badiey Mohsen , Luo Jing , Katsnelson Boris , Lynch James
Published: October 2013

During the Shallow Water 2006 (SW06) experiment, several internal wave (IW) events were recorded by moving and stationary instruments simultaneously with the acoustic propagation tests. More than 50 IW events were recorded using the University of Delaware’s R/V Sharp’s radar. On this ship, a J15 sound source transmitted various acoustic signals at different bearings and ranges to the Woods Hole Oceanographic Institution’s vertical and horizontal hydrophone arrays. During one of the IW events, the acoustic source was kept at a constant water depth while moving in horizontal plane with the advancing internal wave front. This internal wave packet, named Event 50, was also recorded by R/V oceanous radar a few kilometers away. The reason for placing the sound source on the advancing IW front was to examine the effects of azimuthal variability of the waveguide on the acoustic propagation. A detailed transition of the waveguide as the internal wave progressively occupied the acoustic propagation track between the source and receiver is reported. It is shown that the intensity peaks at small angles between the acoustic track and the internal wave front where sound intensity focusing and defocusing occurs. [Work supported by ONR 321OA and CRDF, and RFBR.]
Intensity measurements and fluctuations of acoustic transmissions from the Research Vessel Sharp during Shallow Water 2006.
Authors: Dossot Georges A. , Miller James H. , Potty Gopu R. , Lynch James F. , Newhall Aurthur E. , Badiey Mohsen
Published: October 2013

During the Shallow Water 2006 (SW06) experiment, the University of Delaware’s R/V Sharp transmitted various acoustic signals at several different bearings and ranges to the Woods Hole Oceanographic Institute’s vertical and horizontal hydrophone line array. The array was strategically positioned near the shelfbreak front, and in an area where internal waves are known to occur. During several of the R/V Sharp’s acoustic transmissions, internal waves passed through the sound field. The internal waves and the shelfbreak front can cause complex multimode and multipath interference patterns which result in intensity variations of received acoustic signals. This presentation provides an overview of the R/V Sharp’s transmissions, and the corresponding intensity fluctuations of received signals at the array. These fluctuations are compared to internal wave events that were recorded at both the transmission and reception locations. These internal wave events were also imaged by the R/V Sharp’s radar and satellite-based radar. Following the work of Fredricks et al. [J. Acoust. Soc. Am. 117, 1038 (2005)], statistical distributions are fit to the calculated intensities for different transmission directions, distances, and times. These distributions are compared to modeled data with and without the internal wave field. [Work sponsored by the Office of Naval Research.]
Time-frequency pattern of the sound intensity fluctuations of midfrequency signals in presence of internal waves in Shallow Water 06 experiment.
Authors: Katsnelson Boris , Grigorev Valery , Lynch James
Published: October 2013

In given paper fluctuations of intensity of sound signals, radiated by the midfrequency source (R/V Knorr) during ∼5 h were studied. Broadband signals (2–8 KHz) were received by four single hydrophones fixed at the bottom (SHRUs) placed at different distances from the source (from 4 to 12 km). These four acoustic tracks have different directions relative direction of propagation of the train of intensive internal waves (the corresponding angles in horizontal plane are from ∼5 to ∼15 deg). Time-frequency diagrams were constructed using frequency filtering of the spectrum of broadband signals with sliding narrow window. Temporal dependences of intensities of received signals within frequency window were constructed for period 14:00 until 19:00 GMT for experiment carried out on 13 August. During this time train of internal solitons was registered, propagating toward the coast. Mentioned time-frequency diagrams demonstrate specific features of influence of internal waves on the temporal variations of the sound intensities at four SHRUs. More exactly variations of predominating frequency in spectra correspond to variations of positions of the solitons at the acoustic tracks. Results of experimental data are compared with theoretical estimations. [Work was supported by RFBR and CRDF.]
Ultrasonic manipulation in microfluidic chips for accurate bioparticle handling.
Authors: Wiklund M. , Manneberg O. , Svennebring J. , Vanherberghen B. , Onfelt B. , Hertz H. M.
Published: October 2013

Micro-manipulation of cells or other bioparticles has important applications in biological and biomedical research. Dielectrophoresis and optical tweezers are the classical tools in this field. Ultrasonic standing wave (USW) technology is presently emerging as powerful alternative, especially in microfluidic chips and other miniaturized systems. In this contribution we will review our present activities in USW-based particle manipulation in microfluidic chips. Recent experiments and simulations allow us to tailor the spatial distribution of the USW force field by multi-frequency actuation and appropriate microchannel/transducer resonance design. We introduce the concept of ultrasonic micro-cages for single-cell or single-particle 3-D ultrasonic manipulation. It is shown that these manipulation tools can be combined with high-resolution optical microscopy, thereby allowing state-of-the-art characterization of individual cells. Frequency-modulation is shown to stabilize the manipulation performance as well as allowing flow-free transport of particles and cells. Environmental control inside the channels has been achieved and proliferation and viability studies are promising. Finally, for bio-analysis, we demonstrate potential for femtomolar bio-analytical sensitivity in bead-based assays using USW enrichment.
Nonlinear ultrasonic standing waves in bubbly liquid: A numerical study.
Authors: Christian Vanhille , Cleofé Campos-Pozuelo
Published: October 2013

This study deals with the behavior of nonlinear ultrasonic standing waves in a bubbly liquid. A water air mixture is considered. The SNOW-BL numerical code gives the solution of a differential system coupling the nonlinear bubble equation with the linear wave equation. Several kinds of high power standing waves which may be useful in biomedical applications are considered here: pulses propagating in water with air bubbles clouds or layers, harmonic waves in a bubbly resonator, non-resonant standing waves in a fluid with bubbles. Conclusions about acoustic pressure distributions, waveforms, and frequency content, as well as mean and rms pressures, are given. Particular acoustical effects induced by the dynamics of the air-bubbles on the pressure standing wave are commented. Comparisons with results in homogeneous fluids are also presented. [Work supported by DPI2008-01429.]
Two-dimensional numerical simulations for the time-averaged acoustic forces acting on a rigid particle of arbitrary shape in a standing wave.
Authors: Wang Jingtao , Dual Jurg
Published: October 2013

The time-averaged acoustic force can be applied to many practical fields such as contactless particle manipulation in biomedicine. It is necessary to accurately predict the mean forces on suspended obstacles to design ultrasonic particle manipulators. Although there have been many analytical solutions on this topic, it is difficult to determine the acoustic forces on obstacles under more complex system conditions such as proximity to the chamber wall, complex viscous function, acoustic streaming, and complicated particle shapes. Therefore, the numerical modeling may become a powerful tool. In this paper, the time-averaged forces, which act on rigid 2-D particles with different shapes in ideal and viscous fluids exerted by a standing sound wave field, are computed by solving the Navier-Stokes equations directly using the finite volume method (FVM) technique. The cylinder results agree well with Haydock’s theoretical prediction and his lattice Boltzmann simulations. Then, the force and torque acting on a needle shaped particle in a standing wave are calculated and discussed in detail. Furthermore, the viscous effects of the host medium are also investigated. Our program with the FVM algorithm proves to be quite suitable for calculating the acoustic forces in standing waves.
Investigation of single crystals for U.S. Navy standard electro-acoustic transducer applications.
Authors: Szelag Jeffrey A. , Howarth Thomas R.
Published: October 2013

The Underwater Sound Reference Division (USRD), Naval Sea Systems Division in Newport, RI, is the U.S. Navy’s primary source for the provision of standard underwater electro-acoustic reference transducers. USRD has over 40 years of traceable and repeatable historic data for each transducer that is currently available for underwater calibrations and experiments. As such, USRD’s primary focus is on the continuous development of new reference transducers incorporating the latest technologies available. Requirements for these standards include repeatability over extended time, traceability, and ease of maintenance. This presentation covers an on-going USRD investigation to feature single crystal PMN-PT as the active substrate in the current F41 program transducer. In addition, lossy rubber substrates are being examined to replace the legacy corprene passive materials in order to extend the operating depths of the transducer. Our presentation will begin with an overview of the fabrication techniques followed by experimental underwater data comparing the new active and passive materials with the traditional F41.
A generalized differential effective medium model of piezoelectret foams.
Authors: Haberman Michael R.
Published: October 2013

Piezoelectrets are closed-cell foams consisting of a continuous polymer matrix containing preferentially oriented and electrically polarized ellipsoidal voids. These materials display low density, low characteristic impedance, thicknesses on the order of 100 μm, and potential to act as conformal transducers on complex geometries. They therefore provide an intriguing alternative to piezoelectric ceramics and piezopolymers for applications such as air-coupled ultrasonics or underwater receive elements. Unfortunately, some fundamental attributes of piezoelectret behavior, such as their nonmonotonic change in receive sensitivity with increasing ambient pressure, remain unexplained by physical modeling or experiment. To explain this and other behavior, this work develops a fully coupled multiscale microelectromechanical model which captures the void-scale physics and predicts macroscopically observed piezoelectric properties. The model employs volume averaged Green’s function solutions of the three-dimensional stress equilibrium equations and Gauss’s Law. The resulting model approximates the effective stiffness, dielectric permittivity, and piezoelectric coupling tensors as a function of the constituent material properties, void fraction, shape, and orientation, as well as the deposited charge density. Strain localization tensors of the model are then employed to approximate piezoelectret dependence and external pressure. Model results show good agreement with experimental results and data from the literature.
Mechanical characterization of capacitor microphones for analysis and study.
Authors: Chuang YuFan , Pawar S. J. , Huang Jin H
Published: October 2013

An attempt is made to investigate the mechanical properties of the diaphragm of capacitor microphone using MTS Tytron 250 micro-force testing machine. The compliance of the diaphragm is calculated from the force-displacement diagram. The simulation of the microphone is carried out using equivalent circuit method. The mechanical parameters like mass (measured), compliance (measured and calculated), and resistance (assumed from literature) are being used to formulate mechanical domain of microphone in equivalent circuit model. The sensitivity curve of microphone is being plotted. Simultaneously, the experimental measurement has been carried by PULSE Electroacoustics with the software Sound Check in an anechoic chamber. The simulation and experimental results for sensitivity are found to follow each other within a wide frequency range. The characteristic investigation is carried out using validated equivalent circuit model for parametric study of microphone. [Work supported by Contract Nos. NSC 95-2221-E-035-013-MY3 and 95-2221-E-035-087. The authors would like to thank Leo Liao and Jack Wei of Merry Electronics Co. Taiwan and Listen Inc. for supplying Sound Check measurement.]
Bridging the gap between macro- and microdevices for manufacture of piezoelectric energy harvesters.
Authors: Chait Arthur L.
Published: October 2013

In this presentation, materials engineer and entrepreneur, Arthur L. Chait will show why there is a gap at the miniature scale when building complex devices with multiple materials. He will explain why few technologies can handle several materials, with complex geometries, in small parts. Miniature piezoelectric (PZ) energy harvesters are an example of this challenge. Mr. Chait will describe his piezoelectric energy harvester, designed for tire pressure sensor systems. This tiny device uses PZ materials to convert some of the vibration of the tire into electricity. The electric current is stored in a capacitor and used to power the system. Audiences will learn why it is difficult and costly to build a small, rugged system to power a tire sensor. The anatomy of this device includes at many diverse materials and five basic design elements. These are bonded into a strong package about the size of a contact lens. Building this energy harvester would be almost impossible with conventional manufacturing techniques. Mr. Chait will share a relatively new solution; i.e., a print deposition technique that produces thousands of parts simultaneously from many different materials. Active elements like circuits, catalyst beds, mixing chambers, capacitors, and piezoelectric actuators are produced all in one step.
Acoustic energy harvesting using an electromechancal Helmholtz resonator.
Authors: Liu Fei , Phipps Alex , Horowitz Stephen , Cattafesta Louis , Nishida Toshikazu , Sheplak Mark
Published: October 2013

This talk presents the development of an acoustic energy harvester using an electromechanical Helmholtz resonator (EMHR). The EMHR consists of an orifice, cavity, and a piezoelectric diaphragm. When the acoustic wave is incident on the EMHR, a portion of acoustic energy is converted to electrical energy via piezoelectric transduction in the diaphragm of the EMHR. Moreover, the diaphragm is coupled with energy reclamation circuitry to increase the efficiency of the energy conversion. Two power converter topologies are adopted to demonstrate the feasibility of acoustic energy reclamation using an EMHR. The first is comprised of only a rectifier, and the second uses a rectifier connected to a flyback converter to improve load matching. Experimental results indicate that approximately 30 mW of output power is harvested for an incident sound pressure level of 160 dB with a flyback converter. Such power level is sufficient to power a variety of low power electronic devices.
Theoretical study of thermoacoustic power conversion with a piezoelectric transducer.
Authors: Jensen Carl , Raspet Richard
Published: October 2013

A heat-driven thermoacoustic engine prototype has been designed with a piezoelectric transducer as an electroacoustic transformer. The design under consideration uses a bending, unimorph transducer placed between two identical thermoacoustic engines operating out of phase such that the transducer is driven in a push-pull fashion. The thermoacoustic engine is modeled using a one-dimensional low amplitude simulation. The piezoelectric unimorph is modeled by an electroacoustic equivalent circuit aimed at capturing the first order resonant behavior of the transducer; loss mechanisms from hysteretic behavior of the dielectric or elastic properties are not considered by the model. Issues in optimizing the geometry of the model will be presented as well as comparisons to other forms of waste heat power harvesting such as thermoelectric.
Comparison of the mechanics of the brass players’ lips during slurred note transients.
Authors: Chick John P. , Logie Shona M.
Published: October 2013

When sounding a note on a brass instrument, a strong coupling is established between the vibrating lips of the player and the air column resonance. In moving between notes as smoothly as possible, or “slurring,” there is a transition from one strongly coupled, steady-state, regime of the lip/air column to a different steady-state coupling of the lip/air column. To the listener, there are sometimes subtle differences in the sound of the transition between notes depending on how this transition is achieved: by lip slur, valve slurs, and, in the case of the trombone, slide slurs. This paper uses data collected from high speed video capture of the players’ lips, synchronized with microphones in the mouthpiece and the bell of the instrument, to investigate and compare the motion of the brass players’ lips for different types of slurred internote transients.
Acoustical history of the tuba.
Authors: Myers Arnold
Published: October 2013

Low-pitched valved brass wind instruments are often described generically as tubas. In fact, the term “tuba” covers a broad family of instruments, with sounding lengths ranging from the 8 ft C of the classic French orchestral tuba to the 18 ft Bb of the brass band and orchestral contrabass. The first instrument designated as a tuba was introduced in 1835, and since then a variety of models differing in bore profile as well as in nominal pitch have been used. This paper explores the the historical development of the tuba family from an acoustical perspective, presenting and discussing measurements of bore profile and input impedance for a number of representative instruments from different periods and musical traditions.
The double bell descant euphonium.
Authors: Young Frederick J.
Published: October 2013

A euphonium is presented that has better intonation and is easier to play in the extreme registers. It is a complete double horn having five double valves in contrast to the incomplete normal double French horn having only three double valves. The valves descend 2, 1, 3, 4, and 5 semitones from the open tones. The large bell is for the B♭ standard part of the instrument. A switch valve activates the smaller alto bell in the key of high E ♮ and sends the air through the five shorter valve slides and out the small bell. The fundamental frequency of the E side is 82.4 Hz or six semitones above the fundamental of the B♭ euphonium. The key of E rather than F or E♭ enables all notes in the complete range (about 29–988 Hz) to be played with a single tunable valve slide. Either of the other keys would introduce a need for one additional valve or compromise the intonation.
Numerical simulation of acoustical shock waves: Beyond the parabolic approximation.
Authors: Dagrau Franck , Renier Mathieu , Coulouvrat François , Marchiano Regis
Published: October 2013

The KZK equation is the reference equation for the modeling of finite amplitude diffraction effects. It has been applied with success to many applications in various domains. Nevertheless, the parabolic approximation underlying the KZK equation limits the validity of this one to narrow-angle propagation. A new formulation of the Kuznetsov equation enables us to go beyond the parabolic approximation for the diffraction effects in the homogeneous case, the parabolic approximation being now limited only to the heterogeneous perturbation which is one order of magnitude smaller. This method formalizes and generalizes to the weakly heterogeneous case the previous work of Christopher and Parker [J. Acoust. Soc. Am. 90, 488–499 (1991)]. Special attention is paid to the implementation of boundary conditions (such as absorbing or perfectly matched layers). Several validation tests will illustrate the potential of the method, such as nonlinear focusing or scattering. Applications to sonic boom propagation in a turbulent atmosphere will finally be discussed.
Numerical methods for weak shock propagation and diffraction around a microphone.
Authors: Sparrow Victor W.
Published: October 2013

There are two interrelated goals for this presentation. The first goal is to give an overview of available numerical approaches for weak shock propagation. There are multiple approaches available, including formulations based on the Burgers equation, KZK or NPE equations, the second-order equations of nonlinear acoustics, the Navier-Stokes equations, or the Boltzmann equation. There are also multiple numerical techniques for discretizing each of underlying equations, and while some approaches give special treatment to weak shocks others handle the shocks automatically. The second goal of this presentation is to show recent simulation results for an explosion shock interacting in two dimensions with a microphone. The diffraction of the weak shock around the microphone housing does turn out to be amplitude dependent. It is only a modest effect, increasing for higher amplitudes. This knowledge is important for precise, close-range blast source characterization. In the future, the nonlinear diffraction of weak shocks around transducers also should be investigated for finite amplitude biomedical ultrasound, since the mechanisms for nonlinear diffraction are almost identical for ultrasound and explosion waves. [Work supported by U.S. Army ERDC-CERL.]
Comparison of time and frequency domain approaches to simulate propagation of weak shocks.
Authors: Averiyanov M.V. , Yuldashev P.V. , Blanc-Benon Ph. , Khokhlova V.A.
Published: October 2013

Simulations of acoustic fields using finite-difference methods are performed either in time or frequency domains. A method of fractional steps with an operator splitting procedure is frequently applied to solve nonlinear equations of the evolution type. Either time or frequency domain solvers can be used to calculate different terms in the equation over a propagation grid step. In this work, several algorithms that have been used to simulate quadratic nonlinear term in the Burgers or KZK-type evolution equations are applied to model the propagation of weak shocks. Shock capturing schemes of Godunov type, exact analytic solution with further extrapolation of the waveform over a uniform temporal grid, time-domain conservative schemes, direct modeling in the frequency domain, and asymptotic spectral approach are compared. The parameters of the schemes that would provide the results of the same accuracy, an artificial absorption necessary for stability of the schemes, resolution of shocks, and internal viscosity of the algorithms are discussed. It is shown that the Godunov-type algorithm is better suited to model weak shocks with sufficient accuracy achieved with only three temporal grid points per shock. [Work supported by the RFBR and NIH EB007643 grants.]
A shock-fitting method for general nonlinear progressive waves.
Authors: Coulouvrat Francois
Published: October 2013

Many physical phenomena are concerned with the propagation of weak nonlinear waves that can be modeled under the form of a generalized Burgers equation. Physical examples include nonlinearities that can be either quadratic (nonlinear acoustical waves in fluids or longitudinal waves in solids), cubic (nonlinear shear waves in isotropic soft solids), or nonpolynomial (Buckley-Leverett equation for diphasic fluids, models for car traffic, Hertz contact in granular media). A new weak shock formulation of the generalized Burgers equation using an intermediate variable called “potential” is proposed. This formulation is a generalization to nonquadratic nonlinearities of the method originally proposed by Burgers himself in 1954 for his own equation, and later applied to sonic boom applications by Hayes et al. (1969). It is an elegant way to locate the position of a shock. Its numerical implementation is almost exact, except for an interpolation of Poisson’s solution that can be performed at any order. It is also numerically efficient. As it is exact, a single iteration is sufficient to propagate the information at any distance. It automatically manages waveform distortion, formation of shock waves, and shock wave evolution and merging. The theoretical formulation and the principle of the algorithm are detailed and illustrated by various examples of applications.
Using structural acoustics methods to study new materials.
Authors: Maynard J. D.
Published: October 2013

In structural acoustics it is usually necessary to know the vibration properties of the structure under study, and this requires knowing the elastic constants of the materials involved. A relatively recent and powerful method for measuring elastic constants is resonant ultrasound spectroscopy (RUS). Very new and exotic materials for structures often require RUS; the reason is that new materials, when first fabricated, are often available only in very small samples (a few hundred micrometers) or as thin films on substrates, and RUS is the best method for handling such samples. On some occasions samples are fragile or chemically reactive so that they cannot be polished into the shapes required by conventional RUS. Thus, it has been necessary to develop a RUS analysis for arbitrarily shaped samples. This has been accomplished by borrowing a method from structural acoustics: the finite element method (FEM). The discussion of the application of FEM to RUS for arbitrarily shaped samples will include bridging the gap between theory (involving matrices as boldfaced symbols without indices in textbooks on FEM) and actual lines of computer code. Applications of the RUS method for materials will also be discussed.
A three-dimensional Wiener-Hopf technique for general bodies of revolution, Part II: Substructuring and implementation.
Authors: Martinez Rudolph , Ting Carina
Published: October 2013

This paper begins with a brief review of Part I’s main ideas and conclusions regarding: (a) Operator-induced symmetry and reciprocity leading to compatibility of the halfplanes of analyticity between the integral equation’s non-translational kernel and those of the Fourier-transformed displacements and pressures on the surface of a scattering or vibrating body of revolution; and (b) subsequent spectral factorizations in juxtaposition to those of the classical Wiener–Hopf case for the planar geometry. The spatial and spectral domains in question refer to the arclength variable along the body’s generator and to its transform wavenumber, respectively. The analysis described in this Part-II paper brings out some of the additional positive consequences of the pre-symmetrization of the integral equation that governs the response of the coupled fluid and structure. It then applies standard substructuring schemes to extend Part I’s formulation to include departures from axisymmetry resulting from generic appendages as discontinuities along the shape’s circumferential coordinate. The presentation ends with sample applications of its new 3-D Wiener–Hopf technique to canonical shapes of revolution, and with a summary of the physical insights made possible by the new approach relative to numerical results by boundary elements.
Perceptual learning and expectations: Cognitive mechanisms in speech recognition.
Authors: Nusbaum Howard
Published: October 2013

There is substantial plasticity in adult perceptual processing of speech that cannot be accounted for by most theories. Even 1 h of training on low-intelligibility synthetic speech can improve recognition by 20 percentage points for novel words. Whether speech perception is based on auditory properties or articulatory properties, few theories acknowledge the role of cognitive processes, and some explicitly exclude these mechanisms. Evidence will be examined suggesting perceptual learning of phonetic information in adult listeners involves processes such as attention and working memory. In addition, evidence will be examined that speech perception can be influenced, if not typically guided, by listeners’ expectations about speech. In some cases, expectations may be derived by explicit instruction to listeners, and in others, from contextual information. For example, research on talker normalization and perception of sinewave speech has demonstrated that listeners’ expectations about the speech signal change perceptual processing. Evidence will be discussed suggesting mechanisms that mediate this effect of expectations and compare this to mechanisms involved in perceptual learning. Perceptual learning may depend on the same kinds of cognitive mechanisms involved in the top-down guidance of perception by expectations and these mechanisms may be necessary for stable phonetic perception. [Research supported by NIDCD.]
Hearing the forest despite the trees: Perceptual learning of systematic variation in speech.
Authors: Nygaard Lynne C.
Published: October 2013

A fundamental problem for the understanding of spoken language processing is listeners’ robust perceptual constancy in the face of enormous variability in the instantiation of linguistic form. On the one hand, listeners are sensitive to the fine-grained structure of linguistic segments that signal differences among talkers and speaking styles. On the other hand, listeners tolerate large discontinuities in this same fine structure forming robust, perceptually constant linguistic categories. Data from a perceptual learning paradigm addressing both the limits and flexibility of speech perceptual mechanisms will be presented and discussed in light of evidence for perceptual learning of accented speech. In a series of studies, listeners were exposed to accented English under learning conditions in which the opportunity to compare across instances varied. At test, generalization and long-term retention of perceptual learning were evaluated. The results suggest that adaptation to lawful variation in speech is fundamentally influenced by the character and structure of the learning experience. These findings suggest cognitive constraints on behavioral and representational plasticity in speech perception and spoken language processing.