bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurement and modeling of nonlinear waveforms in high-intensity focused ultrasound fields
Authors: Canney Michael S. , Bailey Michael R. , Khokhlova Vera A. , Smagin Misha A. , Sapozhnikov Oleg A. , Crum Lawrence A.
Published: October 2013

Direct measurement of HIFU fields in situ is important for the accurate prediction of thermal and mechanical bioeffects, as well as for the development of standards for medical systems. An experimentally validated numerical model can be an effective tool in both laboratory and clinical settings when direct measurements are not possible. Calculations with a KZK-type model and measurements with a fiberoptic probe hydrophone were employed together to characterize HIFU fields in water and in a tissue-mimicking gel. To determine the boundary conditions for simulations, the normal velocity distribution on the transducer surface was reconstructed using acoustic holography and combined with acoustic power measurements. At the focus, highly nonlinear waveforms (+700 and −150 bars peak pressures) were obtained both experimentally and numerically, which differed significantly from waveforms linearly extrapolated from low-amplitude results. Strongly distorted shock waveforms were localized in an axial region much smaller than the half-maximum beamwidth of the transducer excited at low level. At the highest excitation levels, the simulations predicted frequency content higher than was measurable in our configuration. Simulations also show that if these frequencies are not included, predicted heating rates are significantly lower. [Work is supported by NIH DK43881, NSBRI SMS00402, and RFBR.]
The acoustic design of the research vessel SHARP
Authors: Bahtiarian Michael
Published: October 2013

The R/V HUGH R. SHARP is a general purpose research vessel that is owned and operated by the University of Delaware. It has been designed to achieve the International Council for the Exploration of the Seas (ICES) underwater noise limit for Fisheries Research Vessels. This paper describes the design process, construction details, and final results with regard to the acoustic design of this ship. Both compartment airborne noise and underwater radiated noise predictions were carried using a proprietary shipboard noise prediction program. Noise control treatments that were used include: vibration isolated machinery, double-stage isolated diesel generators, damping tiles, special acoustic insulation, and floating floors. After the vessel was completed a series of at-sea tests was performed to check compliance to vibration, compartment noise, and underwater noise. Two problems were discovered with underwater noise levels. One was related to a gearbox and the other was related to the propellers. A discussion of both issues and the final results are given in the paper. [Support provided by the University of Delaware, College of Marine Studies, in particular Mr. Matthew Hawkins, Director of Marine Operations.]
The development of picosecond ultrasonics
Authors: Maris Humphrey J.
Published: October 2013

Brown University has been a center for acoustics research for a very long time. Over the past 20 years, efforts have been directed towards the development of a new measurement technique that makes possible experiments on very thin films and other small structures of current interest in the computer industry. This method has also made it possible to make sound attenuation measurements over the frequency range from 10 GHz up to approximately 1000 GHz. The method will be described and some examples of its application will be presented.
Effects of correlated and uncorrelated interfering noise on interaural time delay (ITD) detection
Authors: Kolarik Andrew J. , Culling John F.
Published: October 2013

Results are reported from two binaural discrimination experiments. The first measured ITD discrimination threshold for broadband noise in the presence of interaurally correlated interfering noise. Six listeners performed an adaptive 2I-2AFC discrimination task with 100-ms stimuli composed of delayed and diotic noises (0–3 kHz) mixed in various proportions (1, 0.75, 0.563, 0.422, 0.316, 0.237, and 0.178). A regression analysis showed that thresholds doubled for every halving of the proportion of delayed noise power in the stimulus. The second experiment measured ITD discrimination thresholds for a range of interaural correlations obtained by mixing correlated and uncorrelated noise before applying the delay. Three listeners performed 2I-2AFC discrimination tasks at correlations of 1, 0.75, 0.5, 0.25, 0.2, 0.15, 0.1, and 0.05, and durations of 100, 500, and 1000 ms. Seventy-one percent of the threshold were obtained using psychometric functions. Thresholds more than doubled for each halving of the correlation at all three stimuli durations tested.
Optimizing information-transfer rates for human communication
Authors: Reed Charlotte M. , Durlach Nathaniel I. , Tan Hong Z.
Published: October 2013

This research is concerned with investigating the factors that contribute to optimizing information-transfer (IT) rate in humans. This issue has important ramifications for the design of human-machine interfaces in a wide variety of applications, including virtual environment and teleoperator systems as well as sensory aids for persons with impaired vision and/or hearing. Based on the results of several early studies from the 1950s, a general rule of thumb has arisen in the literature which suggests that IT rate is dependent primarily on the stimulus delivery rate and is optimized for presentation rates of 2–3 items/second. Thus, the key to maximizing IT rate is to maximize the information in the stimulus set. Recent data obtained with multidimensional tactual signals, however, appear to be at odds with these conclusions. In particular, these current results suggest that optimal delivery rate varies with stimulus information to yield a constant peak IT rate that depends on the degree of familiarity and training with a particular stimulus set. We discuss factors that may be responsible for the discrepancies in results across studies including procedural differences, training issues, and stimulus-response compatibility. [Research supported by Grant No. R01-DC00126 from NIDCD, NIH.]
Effects of reliable spectral-temporal characteristics of listening context on perception of monophthongs and diphthongs
Authors: Kluender Keith R. , Kiefte Michael
Published: October 2013

Brief experience with reliable characteristics of listening context, such as a precursor sentence, alters perception of subsequent vowel sounds [M. Kiefte and K. Kluender, J. Acoust. Soc. Am. 112, 2248 (2002)]. For example, an appropriately filtered precursor sentence serves to perceptually cancel effects of second formants (F2) of vowel sounds, forcing listeners to rely solely on spectral tilt for identification. Auditory systems effectively absorb spectral characteristics, including formant peaks, if those characteristics are reliable (redundant) properties of the listening context. Present studies investigate whether this perceptual calibration extends to reliable spectral-temporal properties. Listeners identified a series of stimuli with incremental increases in slope of F2 that varied perceptually from /u/ to /ui/. When repeated formant transitions, exactly matching those of the target vowels, were added to precursor sentences, /i/ percepts predominated despite no stimuli being appropriate for /i/ in isolation. When repeated formant transitions were reversed in precursors (high to low frequency), the same results were obtained. Because perceptual absorption of reliable acoustic characteristics was indifferent to F2 trajectory, it appears that processes that calibrate to reliable properties of a listening context are sensitive only to spectral, not temporal, composition of listening context. [Work supported by SSHRC and NIDCD.]
Compensation for coarticulation: Three theories compared
Authors: Viswanathan Navin , Magnuson James S.
Published: October 2013

Classification of a /da/-/ga/ continuum shifts towards more /ga/ responses following /al/ and more /da/ responses following /ar/. Theories explain this as compensation for coarticulation: in natural speech, if speakers must transition from relatively front (/l/) to back (/g/) places of articulation, they will be unlikely to reach the optimal place of articulation. Thus, after /l/, /g/ is likely to be produced further forward than usual and, following /l/, ambiguous tokens in a /d/-/g/ continuum will often be perceived as /g/ with place of articulation shifted by coarticulation. The current study compares the perceptual effects of American English /r/ and /l/ with those of Tamil /R/ (trilled) and /L/ (retroflex). /R/ shares its place of articulation with /l/ but is categorized as an allophone of /r/ by American English speakers. Similarly, /L/ shares its place of articulation with /r/ but is classified as an instance of /l/. However, the acoustic relationships between the Tamil and American English phones are complex, potentially leading to conflicting predictions from auditory contrast and other theoretical explanations of compensation. Our acoustic analyses and experiments examine whether compensation depends upon place of articulation, acoustic cues that might produce contrast effects, or perceptual classification of a phoneme.
Experience-driven effects of visual cues in speech perception
Authors: Stephens Joseph D. W. , Holt Lori L.
Published: October 2013

The integration of information across modalities is a key component of behavior in everyday settings. The current study examined the extent to which experience drives multimodal speech integration. Two groups of participants were trained on combinations of speech sounds with corresponding videos of an animated robot, whose movements and features bore no resemblance to speech articulators. Participants’ identification of acoustically presented consonants was influenced by simultaneous presentation of learned visual stimuli in a manner that reflected the correlation structure of auditory and visual cues in training. The influence of novel non face visual cues on speech perception developed over the course of training, suggesting that experience altered the perceptual mechanisms used in combining this cross-modal information. Pairings of auditory and visual cues given to two groups of participants resulted in patterns of bimodal perception that differed in systematic ways. Perceptual integration of the newly learned visual cues with auditory speech was not optimal, reflecting a bias toward the sound cue. The findings are discussed in reference to current models of speech perception and multimodal integration.
Parsing voicing cues: A context effect predicted by feature cue parsing theory
Authors: Van Worthe Donna , Celi Jillian , Gow David
Published: October 2013

Factors including lawful assimilation conspire to produce overlapping temporal distributions of phonetic feature cues for neighboring segments. Gow’s feature cue parsing model [Gow, Perception and Physics, 65, 575–590 (2003)] suggests that listeners rely on perceptual grouping mechanisms to integrate multiple cues and align them with correct segmental positions. While this account was developed to address progressive and regressive context effects found in the perception of lawfully assimilated speech, its strong form predicts that similar context effects may be found in the perception of speech where there is similar overlap in feature cue distribution, even if such overlap is not the result of a lawful phonological process. This hypothesis was examined in a series of speeded 2AFC experiments in which voicing cues were manipulated in adjacent fricatives and stops. A regressive context effect was found in the perception of the fricative in a peace-peas voicing continuum, which was strongly affected by the voicing of a following stop (e.g., pay versus bay). Similarly, listeners showed a progressive context effect in the perception of stops in a pay-bay VOT continuum when these items were preceded by voiced versus voiceless fricatives. These results are discussed in terms of competing interpretations of assimilation context effects. [Work supported by NIH R01DC3108.]
Could backward recognition masking play an important role in speech contrasts?
Authors: Gaston Jeremy R. , Pastore Richard E.
Published: October 2013

Auditory backward recognition masking (BRM) is the interference in recognition by a following stimulus for some aspect of a clearly detectable target. BRM has been studied for stationary targets, with its conjectured relevance largely limited to the sensory storage and encoding of simple (nonspeech) auditory properties. Could BRM play an important role for more complex stimuli—specifically speech contrasts? The current study systematically investigates BRM interference for speechlike analogs of F2 transitions in varying spectral context that mimic the properties of speech contrasted by place of articulation. Initial and final transitions in isolation show equivalent recognition. Adding a vowel F2 equivalent significantly increases thresholds for initial, but not final, transitions. The further addition of a vowel F1 equivalent results in an additional significant increase in threshold for initial position transitions, and a significant decrease for final position transitions. The possible importance of BRM in defining speech contrasts is discussed. [Work supported by NSF.]
Formant deflection directions of the voiced alveolar stop consonant in different vowel contexts
Authors: Li Kang , Story Brad
Published: October 2013

A parametric model of the vocal-tract area function was used to synthesize a series of alveolar stop consonant constrictions imposed on 9 /V1V2/ transitions (e.g., /idae/). The constrictions differed in configurations, places of occurrence along the vocal-tract length, and the onset and release times to create different on-glide and off-glide formant deflection patterns. It was hypothesized that the formant deflection directions caused by the onset and release of the consonant constriction relative to the underlying vowel-to-vowel formant transitions (i.e., without consonant perturbations) provide information about the identity of the alveolar stop. Perceptual tests were conducted to assess the phonemic identities of the formant patterns produced by the model. The model parameter settings used to create the consonant constrictions that were perceived as /d/’s were analyzed to study the coarticulation effect between /d/ and different vowel contexts.
Recognition of Mandarin words heard through single and multiple spectral bands
Authors: Ho Tien , Li Pei-Chun , Young Shuenn-Tsong
Published: October 2013

Two listening experiments were designed to evaluate the applicability of two macroscopic models—the articulation index and the speech recognition sensitivity (SRS) model—towards Mandarin speech recognition. The experiments aimed to identify if there is any synergetic and redundant effect of spectral frequency bands in monosyllabic Mandarin words. In experiment 1, 20 normal-hearing subjects listened to monosyllables through 20 bandpass filters, which have center frequency ranging from 125 to 8000 Hz, 1/3-octave bandwidth, and filter slope of 100 dB/octave. The purpose of experiment 1 was to identify the intelligibility of spectral frequency bands in Mandarin speech. In experiment 2, 10 subjects listened to monosyllables with the combination of 2 or 3 individual bands for investigating the synergetic or redundant interactions. The perceptual outcomes of the second experiment were fitted to both models by statistical regressions, and the results indicated that the contribution of each band to recognition of Mandarin monosyllables was not independent, and the recognition of Mandarin tones, consonants, and vowels showed different redundant and synergetic effects. The SRS model appears to be able to predict the differential effect of linguistic entropy on filter condition.
jT
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E: A user-friendly reimplementation and extension of the T
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E model of speech perception and spoken word recognition
Authors: Strauss Ted J. , Magnuson James S. , Harris Harlan D.
Published: October 2013

jTRACE is a cross-platform Java reimplementation and extension of the TRACE model of spoken word recognition. TRACE (McClelland and Elman, 1986) is a three-layer interactive-activation model of speech perception that takes a pseudoacoustic input representation and accurately simulates many phenomena of human speech processing. The goals of the reimplementation are to provide a user-friendly version of the model that can run on any current computer platform, extend the model with graphing and scripting tools, and thus provide a tool that is powerful enough for intensive research while easy enough to use in a classroom setting. New features in jTRACE include simulation visualization, results graphing, powerful scripting, internal and external noise parameters, adjustable lexical and phonological characteristics, word recognition metrics, data exporting, and saving/archiving tools. A set of historically relevant simulations is bundled with the program. This feature is ideal for educational applications. Any simulation can be saved in a similar format, promoting sharing and replication. jTRACE was validated quantitatively against the original implementation by replicating key simulations reported in the literature. jTRACE can be downloaded freely from  [Work supported by National Institute on Deafness and Other Communication Disorders.]
Adjoint approach to the physical characterization of a shallow-water environment
Authors: Meyer Matthias , Hermand Jean-Pierre , Berrada Mohamed , Asch Mark
Published: October 2013

In underwater acoustics a variety of different applications of adjoint models has been proposed in recent years. Adjoints have been derived for normal modes and for both the standard parabolic equation and Claerbout’s wide-angle approximation. This paper reviews the analytic nonlocal boundary control approach proposed in an earlier paper by the authors [Meyer & Hermand, ‘‘Optimal nonlocal boundary control of the wide-angle parabolic equation for inversion of a waveguide acoustic field,’’ J. Acoust. Soc. Am. 117, 2937–2948 (2005)] and presents a numerical extension that allows direct inversion of the geoacoustic parameters that are embedded in a discrete representation of the nonlocal boundary condition at the water-sediment interface. The effectiveness of this numerical adjoint approach for the physical characterization of a shallow-water environment is illustrated with applications for geoacoustic inversion and ocean acoustic tomography. In particular, it is shown how a joint inversion across multiple frequencies can enhance the performance of the optimization process, especially for the case of a sparse receiver array spanning part of the water column. In an additional example we combine the two applications and discuss the feasibility of geoacoustic inversion in the presence of an uncertain sound-speed profile.
Bathymetry inversion in shallow water using an adjoint method
Authors: Charpentier Isabelle , Roux Philippe
Published: October 2013

Bathymetry inversion is performed at low frequency on a kilometer-scale shallow water waveguide between two vertical arrays of sources and receivers. The inversion is based on the use of the adjoint of a wide-angle Pade PE code. The adjoint is obtained using automatic differentiation software. The bathymetry is decomposed under a limited number of spline functions. Inversion results improve with the number of source/receiver pairs and when a multiple-frequency approach is used. Application to experimental at-sea data is discussed.
A new family of stringed musical instruments
Authors: Léger Sophie , Gaudet Samuel
Published: October 2013

A new family of stringed musical instruments will be introduced. The TritareTM is the first member of this new family and has evolved from the mathematical analysis of the vibrations of networks of strings [Gaudet et al., J. Sound & Vib. 281, 219–234 (2005)]. It is a guitarlike instrument that uses six networks of three string sections (Y-shaped networks) instead of the classical single strings. The sounds that it produces can be more or less harmonic depending on the string attack conditions and the physical configurations of the string networks. A method of customizing the frequency spectrum to contain desired harmonic components will be demonstrated. A numerical model, which uses finite differences, used to simulate the 3D nonlinear vibrations of more complex string networks involving several string sections and junction points will also be described. The harmonic analysis of the frequency spectra resulting from the numerical simulations and experimental measurements will be presented, as well as network configurations which produce very unique and interesting tone colors. Some of these configurations form the basis for a new family of stringed musical instruments. The presentation will include a demonstration of the TritareTM.
Essential elements of acoustical curricula for noise control engineers
Authors: Bernhard Robert J.
Published: October 2013

Because the supply of noise control and acoustical engineers is small, many of the noise control practitioners practicing in general mechanical engineering fields are retrained on the job. These practitioners are often capable in the area in which they are mentored but lack sufficient background to move to new areas. In order to address a broad range of noise control issues, an engineer must be comfortable to work in waves, or modes, or dBese (engineering controls). The essential curriculum for engineering practitioners would include a foundation in each of these approaches as well as the analytical, computational, and experimental background upon which to build engineering solutions. This presentation will include discussion of how these objectives can be met at the undergraduate level, at the graduate level, and through continuing education.
The need for an essential acoustics curriculum and its delivery via distance education
Authors: Sparrow Victor W. , Atchley Anthony A. , Brooks Karen P. , Lauchle Gerald C.
Published: October 2013

Many individuals have identified a need to better educate engineers, industrial hygienists, and architects with an essential acoustical curriculum including noise control techniques. There are less than a dozen major programs training these individuals, and demand far exceeds the supply of education suppliers. One effective method of providing education to busy professionals who otherwise would not be exposed to an essential curriculum is distance education. Approximately 10 years ago Penn State developed a series of noise control engineering courses delivered through CD-ROM. Now with DSL and cable modems more common, full motion video streaming is a preferred delivery method. Students currently take graduate level courses in acoustics at Penn State via resident education, continuing education, and distance education. There is no reason why an essential acoustical curriculum could not be delivered similarly. One benefit of video streaming is an opportunity for both live and archived lecture material. Students can attend live recitation sections while retaining the ability to see archived material on demand. Technology such as high-bandwidth connections, inexpensive webcams, and microphones also allows two-way audio and video for direct student-instructor interaction.
A comparison of intensity discrimination and increment detection as measures of intensity resolution
Authors: Jesteadt Walt , Messersmith Jessica , Leibold Lori , Khaddam Samar , Tan Hongyang
Published: October 2013

Intensity resolution can be measured by determining the threshold for discrimination of two stimuli differing only in intensity or by determining the threshold for detection of an increment in a longer duration stimulus. Better resolution has been reported for the latter task, but the results are inconsistent across conditions and subjects. In the present study, data were obtained for the two tasks in a range of conditions for 12 adult subjects with normal hearing. Thresholds for intensity discrimination and increment detection were measured for a 4000-Hz tone presented at 20, 40, 60, or 80 dB SPL, using a two-track adaptive procedure that estimated levels required for 71% and 89% correct. The increment was 20, 40, 80, or 160 ms in duration. The pedestal was either the same duration as the increment or was 200 ms longer, centered on the increment. Thresholds expressed in units of delta L were more uniform across subjects and conditions for increment detection than for intensity discrimination. Thresholds were lower on average for increment detection than for intensity discrimination at pedestal levels above 20 dB, but only at the shorter increment durations, and thresholds were not consistently lower for all subjects. [Work supported by R01 DC006648.]
Application of force to the cochlear wall: Effect on auditory thresholds, outer hair cell transduction, and distortion-product otoacoustic emissions
Authors: O’Beirne Greg A. , Patuzzi Robert B.
Published: October 2013

Described are the changes in cochlear sensitivity and mechanoelectrical transduction during a novel cochlear perturbation: the application of force to the cochlear wall. While numerous methods exist to create transient shifts in the operating point of the outer hair cell (OHC) transducer, including low-frequency acoustic bias [G. Frank and M. Kössl, Hear. Res. 113, 57–68 (1997)] and hydrostatic bias [A. N. Salt and J. E. DeMott, Hear. Res. 123, 137–147 (1998)], attempts to create prolonged operating point shifts are largely thwarted by the numerous sources of ac coupling in the auditory system which prevent transmission of dc stimuli to the hair cells. The application of force sufficient to deform the otic capsule produced a consistent drop in neural thresholds and a sustained bias of the OHC operating point that did not rapidly adapt back to normal. Near-simultaneous measurements of compound action potential thresholds, distortion-product otoacoustic emissions, the OHC transfer curves derived from low-frequency cochlear microphonic waveforms, and the endocochlear potential were performed. The data provide ample evidence of the resistance of the cochlea to dc mechanical stimuli, particularly those which do not cause a large pressure differential across the basilar membrane. [The authors gratefully acknowledge the surgical assistance of Dr. Peter Sellick.]
Influence of the sweeping direction of the primaries f1 and f2 in the assessment of distortion product otoacoustic emissions (DPOAEs) fine structure
Authors: Aranda de Toro Miguel Angel , Ordon̋ez Rodrigo , Hammersho/i Dorte
Published: October 2013

It was studied if the sweeping direction of the primaries f1 and f2 influences fine structure measurements of the 2f1−f2 distortion product otoacoustic emission (DPOAE). Two different methodologies named DPOAE5ASC (ascending sweep) and DPOAE5DES (descending sweep) were implemented with the commercial system ILO96. Both methods perform fine structure measurements in the same frequency range (1.4–6 kHz) with L1/L2=65/45 dB, f2/f1=1.22 and 0.7 s averaging time per primary presented. DPOAE fine structures were measured in the right ear of 14 normal-hearing subjects with both methods in a balanced experiment and without refitting the sound probe. Results showed that the two methods are highly repeatable and able to detect fine structures even in subjects with low S/N. However, when DPOAE5ASC measurements are compared with DPOAE5DES, fine structures appear shifted and the level contour is altered. A minor level difference was inadvertently induced due to differences in the level calibration procedure of the two methods employed. The significance of this is currently being studied. [Work supported by the Danish Research Council for Technology and Production.]
Individual susceptibility to noise-induced hearing loss: A review
Authors: Henderson Donald
Published: October 2013

After 40+ years of study, we can conclude that there is a great range of individual differences in susceptibility to noise-induced hearing loss (NIHL). The presentation will review and evaluate the major sources of variances: acoustic, where all exposures are evaluated with dBA and some energy-related metric; exogenous, where the effects of noise can be mitigated by external factors such as temperature, coexposure to chemicals, smoking, etc.; endogenous, where the effects of noise are partially related to an individual’s sex, skin color, acoustic reflex, distortion product suppression, degree of fatigue, and genetic factors.
Enhancement between voice onset time (VOT) and F0: Evidence from Kera voicing perception
Authors: Pearce Mary D.
Published: October 2013

Previous research on production data from Kera (a Chadic tone language) has shown that tone plays a major contrastive role, whereas VOT has a lesser role which could indicate an ‘‘enhancing’’ relationship. This paper investigates the roles of VOT and F0 in Kera voicing perception, and compares this to the nontonal language English. Fifteen Kera and 15 English subjects were given voicing judgment tasks over 200 tokens that had been manipulated in PRAAT to cover a range of VOT and F0 values. The results show a marked difference in English and Kera perception reflecting the phonological differences between the two languages. For Kera, F0 is of major importance, while the VOT plays a lesser role in the judgment. The present findings are consistent with a view that whereas in English, the VOT is contrastive and F0 arguably acts as an enhancing cue, in Kera, the tone is the main contrastive cue to voicing perception while the VOT values enhance the tone cues. A bonus finding from the perception tests is that the relationship between VOT and F0 in Kera voicing perception tasks depends on their exposure to French during childhood.
The multiple coherence function for sound field prediction
Authors: Leth Elmkjær Torsten
Published: October 2013

From the uniqueness theorem it is well known that the sound field in a region exterior to the source region can be determined from knowledge of the pressure or the normal fluid velocity everywhere on the enclosing surface. In practice the acoustical field quantities are obtained from space-time discretization. The space-time samples on the enclosing surface and arbitrary field points in the interior to the volume will be considered as input and output processes to a multiple-input–multiple-output (MIMO) system, respectively. The multiple coherence function γy:x2 provides a measure of linearity between a set of inputs and an output independentof the correlation among the inputs. Various system imperfections, however, will lead to a nonunity γy:x2 In particular, spatial sampling, similar to time-domain sampling, requires limited bandwidth to avoid aliasing. Therefore, a sufficient number of sensors must be allocated to ensure γy:x2≊1. In this paper a spherical enclosure is investigated. The objective is to express γy:x2 as a function of internal field point position for different space-time sampling strategies. Simulation results for single plane wave, diffuse fields, and multiple-source fields is presented. Measurement results obtained in a reverberant room are discussed. The work is also useful in active control system design.
Adaptive collaborative array trajectories for optimum passive detection
Authors: Hickman Granger W. , Krolik Jeffrey L.
Published: October 2013

Two major challenges faced by sensor arrays used for passive sonar detection in littoral ocean channels are the suppression of highly dynamic interferers and signal wave-front mismatch resulting from complex multipath propagation. Large static arrays require accurate signal wave-front modeling and a highly stationary noise field to achieve their maximum potential array gain. In this paper, the detection performance of collaborative unmanned underwater vehicles (UUVs) towing short-line arrays is evaluated. In particular, vehicle trajectories which maximize overall probability of detection are computed as a function of the noise-field directionality and target location probability distribution. The UUV trajectories are constrained to share common endpoints connected by a series of line segments for each vehicle. The probability of at least one far-field detection by at least one UUV over the course of their transit is then maximized with respect to the sequence of the vehicles’ headings. The results for a 2D horizontally isotropic noise field indicate that trajectories with a diversity of endfire (or equivalently broadside) bearings maximize detection performance. Scenarios with multiple interferers lead to solutions which minimize backlobe masking of the target. [Work supported by ONR.]
Exploiting temporal coherence models to extend detection range
Authors: Wagstaff Ronald A.
Published: October 2013

Turbulent flow over acoustic sensors and other sources of noise can severely corrupt signals and reduce detection range. The ranges can be much greater when based on the temporal coherences of signals and noise instead of their magnitudes. The signals need not be perfectly coherent to be detected at longer ranges, just more coherent than noise. This is illustrated using a fluctuation-based temporal coherence signal-processing model. This model uses measured data to produce temporal coherence patterns that are random for noise, deterministic for signal, and a blend of the two for small, e.g., negative, signal-to-noise ratio (SNR). Fluctuation-based processing techniques are presented for temporal coherence pattern generation, recognition, and automatic identification of signal presence or only noise in a frequency bin. It is shown for both underwater and atmosphere acoustic data that a signal’s influence in a frequency bin alters the usual random ‘‘noiselike’’ temporal coherence patterns by causing them to cluster. Hence, signal-altered patterns can be recognized and the signals preserved. Corresponding ‘‘noise-only’’ patterns, being random, can also be recognized and attenuated, or eliminated. Using these models results in increased SNR and automatic signal detection at longer ranges with greater confidence. [Work supported by ARDEC and SMDC.]
Joe Blue’s influence on low-frequency, shallow-water acoustics
Authors: Frisk George V.
Published: October 2013

As Superintendent of the Naval Research Laboratory’s Underwater Sound Reference Division, Joe Blue played a key role in the advancement of low-frequency, shallow-water acoustics. Specifically, his leadership and oversight of this unique facility provided an engineering science environment in which low-frequency transducers were developed, calibrated, and maintained. These assets were made available to the research community in ocean acoustics at reasonable cost and have offered dependable, reliable service for more than 25 years. This talk focuses on advances made using the J15-3 transducer, which emerged as a workhorse in numerous experiments in low-frequency (50–500 Hz), shallow-water acoustics. A series of experiments is described in which this transducer was used as the principal source of sound. These measurements led to an increased understanding of acoustic propagation, geoacoustic inversion, and physical oceanography in shallow water. [Work supported by ONR.]
Simulation models of click production in dolphins
Authors: Dubrovskiy Nikolay A. , Urusovskiy Igor A.
Published: October 2013

The simulation model (SM) of dolphin click source originally presented by [Dubrovskiy and Giro, ‘‘Echolocation in Bats & Dolphins,’’ Chap. 10, 59–63 (2003)] was further developed by Gladilin, Dubrovskiy, Mohl, and Walberg, Acoust. Phys. 50, 463-468 (2004). The SM describes movements of a solid sphere frozen in a compliant ring. A jet of air in a duct connecting air cavities brings the sphere into self-oscillations. The SM allows calculating the waveform and sound pressure of the generated clicks. Here the mathematical and simulation model (MSM) of click production in dolphins is further developed. The MSM describes radiation of clicks by bodies comprising of waterlike tissue with different shapes (a ring, a blunted cone) pulsating and (or) oscillating under action of muscles tension. Calculations are made for the energy efficient case when acting force is consecutively applied not to the entire body but to its thin layer, which resulted in action of the progressing wave array. Directivity patterns of such a waterlike compliant body in main directions are similar to that of a rigid body with the same shape and dimensions. Comparisons are made of MSM predictions with properties of an actual radiation field of dolphins (in clicks wave forms, sound pressure levels, and directivity patterns) and dimensions of biological structures supposedly responsible for click production in dolphins.
Listening to fish: Applications of passive acoustics to fisheries
Authors: Rountree Rodney , Juanes Francis , Goudey Cliff
Published: October 2013

Passive acoustics is a rapidly emerging field of marine science that until recently has received little attention from fishery scientists and managers. In its simplest form, it is the act of listening to the sounds made by fish and using that information as an aid in locating fish so that their habitat requirements and behaviors can be studied. We believe that, with the advent of new acoustic technologies, passive acoustics will become one of the most important and exciting areas of fisheries research in the next decade. However, widespread unfamiliarity with the technology, methodologies, and potential of passive acoustics has hampered the growth of the field and has limited funding opportunities. Herein, we provide an overview of important new developments in passive acoustics together with a summary of research, hardware, and software needs to advance the field.
Surround-sound wish list
Authors: Ludwig Bob
Published: October 2013

This presentation describes this engineer’s involvement with surround sound since the days of vinyl LP, 8-track, and four-channel Quadrophonic sound. It includes my experiences as one of the few mastering engineers hired by Digital Theater Systems in 1997 to master and help establish their new 5.1 surround compact disc. In 2005, the author mastered 2 of the 5 Grammy-nominated ‘‘Best Surround Sound discs’’—the SA-CD Dire Straits 20th Anniversary edition of ‘‘Brothers in Arms’’ and the Foo Fighters ‘‘In Your Honor’’ DualDisc. This presentation also includes a short wish list of issues with popular music surround-sound mixes with some suggestions for improvement.
Noise exposure criteria for fish and turtles; lessons learned from criteria for marine mammals
Authors: Gentry Roger L.
Published: October 2013

A committee that is just finishing noise exposure criteria for marine mammals has learned the following lessons that may apply to the writing of similar criteria for fish and turtles. Writing criteria will require scientists from highly diverse backgrounds meeting multiple times over several years. Scientific discourse should prevail throughout; special interests will hinder the writing of science-based criteria. Because empirical data will undoubtedly be inadequate to the task, extrapolation procedures will be needed. Especially lacking will be animal data reporting metrics like SEL and particle motion. The wide diversity of sound types and of animal species will necessitate some grouping within each category. The most efficient format for the criteria will be a matrix of the two groupings. However, existing data will not support a matrix having too many cells. Some criteria will need to be expressed in more than one metric to account for all the relevant aspects of complex signatures. Frequency weighting functions will be needed. Criteria for injury will be easier to write than for behavioral responses due to data availability. Finally, several iterations of the criteria will be needed as science improves. The first version should be written to accommodate change.
Laser generation and detection of zero-group velocity Lamb mode resonance in thin plates
Authors: Prada Claire , Clorennec Dominique , Royer Daniel , Balogun Oluwaseyi , Murray Todd W.
Published: October 2013

Some Lamb modes exhibit a resonant behavior at frequencies where the group velocity vanishes while the phase velocity remains finite. Such a zero group velocity point exists in most isotropic materials for the first-order symmetric mode. Laser sources couple efficiently into this resonance and a sharp peak is observed with source and receiver on epicenter. Moving the detection point away from the source allows us to establish the dispersion curves of the plate and observe the negative phase velocity. We used a modulated diode laser source and a Michelson interferometer to observe the resonance at high frequency. Measurements were made on different material of thickness down to 4μm. The resonance peak is sensitive to the thickness and mechanical properties of plates and may be suitable for the measurement and mapping of nanoscale thickness variations. We also observed this behavior with a 20-ns pulsed YAG laser source and a heterodyne interferometer. The low attenuation in duralumin allows the excitation of a very sharp resonance in a single shot. Thickness variations as small as 0.1μm have been measured in a 0.50-mm-thick duralumin plate. Furthermore, the time decay of the signal provides an estimation of the local attenuation.
Playing with speckle in acousto-optic imaging
Authors: Boccara Albert-Claude , Forget Benoit , Ramaz Francois , Bossy Emmanuel , Gross Michel , Santos Pedro , Jean Florence , Atlan Michael
Published: October 2013

Using light to image in-depth structures and to quantify them in terms of optical (absorption, scattering) properties is a goal for physicists. We will recall the approaches which overcome the strong loss of the photons directional memory in scattering media and their limitations in terms of depth and resolution. Then we will consider hybrid methods which couple acoustics and optics to reach the optical contrast with the acoustic resolution: opto-acoustics, where a locally absorbed laser pulse generates an acoustic signal whose position and depth can be localized by an array of piezoelectric detectors, and acousto-optics (A.O.), where an ultrasonic beam modulates the speckle. We will focus on the principle of A.O. signal generation for tagging spatially selected photons and describe various approaches based on numerical heterodyne holography or heterodyne holography using a photo-refractive beam splitter. To get enough signals through thick tissues (e.g., breast) in a short time we use these techniques at the shot noise limit. Finally we show images revealing optical contrasts in artificial structures or in tissues.
Focusing by use of time reversal of photoacoustic waves
Authors: Bossy Emmanuel , Montaldo Gabriel , Aubry Jean-Francois , Tanter Michael , Fink Mathias , Boccara Claude
Published: October 2013

Time reversal of ultrasonic waves allows focusing of ultrasound through complex media, such as highly aberrating media. On one hand, focusing with time reversal can be performed by backpropagating detected ultrasonic waves generated by a localized ultrasound source. This source classically consists of high acoustic contrasts echoing ultrasonic waves generated by an incident ultrasonic field, or directly by pointlike transducers inserted in the medium. On the other hand, the photoacoustic effect consists of the emission of ultrasound caused by the absorption of light by an optical absorber. In particular, this effect can be used to ultrasonically image a distribution of optical absorbers simply by recording photoacoustic signals on an imaging transducers array. In this work, we perform time reversal of ultrasound generated by a pointlike photoacoustic source in order to automatically focus ultrasound back to an optical contrast. A Q-switched pulsed Nd:YAG laser was used to illuminate tissue phantom with nanosecond laser pulses. Conventional ultrasonic transducers arrays (in the MHz frequency range) and a time-reversal electronics were used to detect, record, and time reverse photoacoustic signals. We show that this allows focusing of ultrasound through highly aberrating medium, and perform acoustical imaging with good resolution within the isoplanetic region surrounding the optical contrast.
Investigation of media with large, negative parameters of nonlinearity and their application to the enhancement of a compact, omnidirectional, parametric source
Authors: Rogers Peter H. , Dufour Etienne , Trivett David H.
Published: October 2013

This paper reports on two media whose acoustic properties are highly pressure dependent and, thus, have large nonlinear parameters (B/A∼−3000 to −5000). One is Xanthan gelatin filled with, 10%, Expancel microspheres. The other is a polyurethane rubber, Polytek 74, with 20% Expancel microspheres. The microspheres have a high bulk modulus at ambient pressure due to the hoop stiffness of the spherical shell. As pressure is increased some of the microspheres buckle, leading to significantly decreased bulk modulus. The decreasing bulk modulus with increasing hydrostatic pressure (negative dc/dp) results in both negative B/A and low sound speed (150 m/s at the minimum), which further enhances nonlinear distortion. These media are used to enhance the efficiency of an underwater parametric source. Experiments on a spherical source with a thin layer (2 cm thick) of the Xanthan gelatin material resulted in a generated difference frequency source level 16 dB higher at 300 Hz, than would be obtained driving the transducer directly at the difference frequency. Experiments on the same source with a thin layer of the microvoided, polyurethane rubber are in progress. This material has a smaller coefficient of nonlinearity but operates over a broader range of hydrostatic pressures.
Nonlinear acoustic detection of buried landmines: A tribute to Joe Blue
Authors: Korman Murray S.
Published: October 2013

As a graduate student at Brown University (∼1978), this researcher was very fortunate to have met Joe Blue at Acoustical Society meetings. As I had little knowledge of the members in the society and an extremely limited grasp of the practical technology behind nonlinear acoustics, Joe was extremely friendly and took the time to answer a long list of questions about nonlinear underwater transducer designs with applications to the parametric array [Muir, T.G. & Blue, J.E. ‘‘Experiments on the acoustic modulation of large-amplitude waves,’’ J. Acoust. Soc. Am. 46, 227–232 (1969)]. This influenced this researcher’s Ph.D. thesis involving experiments on the scattering of sound by sound in the presence of turbulence. Recently, experiments on the nonlinear acoustic detection of buried landmines [Korman, M.S. & Sabatier, J.M., ‘‘Nonlinear acoustic techniques for landmine detection,’’ J. Acoust. Soc. Am. 116, 3354–3369 (2004)] has brought some attention to understanding the difference between classical and nonclassical nonlinearity. As a tribute to Joe Blue, the latest results will be presented involving the connections to mesoscopic nonlinear elasticity and slow dynamics in nonlinear buried landmine detection. Here, tuning curve behavior of the soil-surface vibration over a landmine exhibits a linear decrease in resonant frequency with increasing amplitude. Two-tone test excitation reveals a rich spectrum of combination frequency components useful in detection schemes.