bluuebunny/crossref_metadata_2025 huggingface dataset:
Drill steel research to reduce roof bolting machine operator noise exposure
Authors: Peterson Jeffrey Shawn
Published: October 2013

NIOSH has devoted significant resources to reducing Noise Induced Hearing Loss (NIHL) among the Nation’s miners. As part of this effort, NIOSH’s Pittsburgh Research Laboratory (PRL) employs a large reverberation chamber for sound power level measurements and a hemi-anechoic chamber and beamforming system for noise source identification. One of several research projects at PRL is investigating noise controls to reduce the noise exposure of roof bolting machine operators. Research findings to date suggest that drill steel vibration is a significant source of the noise emissions generated during the bolting/drilling cycle and a major contributor to the operators’ noise exposure. In this presentation, the laboratory and field test methodologies are explained as well as a summary of the data analysis procedures and testing results. Proper implementation of currently available noise controls can reduce sound levels at the operators’ position from 3 to 7 dB(A) under laboratory conditions. Conclusions drawn from these results and the steps taken to generate effective engineering noise controls for reducing roof bolting machines operators’ noise exposures are also covered.
Composite saw blade technology
Authors: Homer John P. , Marraccini Leonard C.
Published: October 2013

Stone saw blades are a significant problem concerning noise in the mining industry. Composite blade core technology provides the means for reducing the amount of noise emission from cutting processes. Copper/steel laminate construction has demonstrated the ability to significantly reduce noise emission by 9.2–12.7 dB. This type of noise control technology has been investigated by MSHA to be published as a proven noise control technology. The purpose of this investigation is to classify and quantify the means by which noise reduction is achieved by a composite blade core. The alternate construction of the blade core serves to increase the mechanical hysteresis of the structure. This lowers the vibratory response of the blade and thereby reduces sound emission. Many methods of evaluation are employed in this analysis. The standard method is a comparison of sound pressure level and full-shift noise dose for a steel and composite blade. Further, vibratory decay measurements were taken to predict sound reduction. Modal testing was also performed to reveal potential resonant operating conditions and to observe the effects of mounting configuration on system response. The results of these analyses provide substantial proof that composite saw blade technology provides significant noise reduction for stone cutting applications.
Control of 24-h blasting noise during construction of light rail tunnels in Portland, OR
Authors: Standlee Kerrie G.
Published: October 2013

In 1993, the Tri-County Metropolitan Transportation District of Oregon (Tri-Met) began construction of the Westside Light Rail project in Portland, OR. The project included the construction of a 3-mile-long twin tunnel through the hillside west of downtown. The original plan called for the tunnels to be excavated from the east using a tunnel boring machine that was supposed to be quick and quiet. However, soon after excavation began, the composition of rock along the tunnel path began to cause problems for the boring machine. Excavation fell behind schedule. Tri-Mets contractor decided that a second excavation team needed to move from the west end of the tunnels toward the boring machine to ensure the project would stay on schedule. Tri-Met requested permission to allow the contractor to conduct 24-h blasting in the vicinity of residences to help catch up in the excavation phase. Daly-Standlee & Associates, Inc. (DSA) assisted in defining noise criteria that could be used to ensure blasting noise would be acceptable at residences and, once blasting began, DSA assisted in developing mitigation measures that could ensure the criteria were met. This paper presents the experience gained by the firm during the tunnel boring project.
Acoustic correlates of talker-reported clear strategies
Authors: Ferguson Sarah Hargus , Poore Meredith A. , Shrivastav Rahul
Published: October 2013

When asked to speak clearly, talkers vary considerably in terms of the amount of intelligibility benefit achieved. The acoustic differences between clear and conversational speech also differ from talker to talker. The present study examined the extent to which clear speech acoustic modifications were consistent with talkers’ descriptions of the strategies they used in the clear speech condition during the recording of a large multitalker database [S. H. Ferguson, J. Acoust. Soc. Am. 116, 2365–2373 (2004)]. Specifically, talkers who did and did not report placing extra stress on keywords in clear speech were compared on a variety of duration, pitch, and amplitude metrics. Results will be discussed in terms of talker differences in awareness of and control of specific aspects of speech production. Clinical implications will also be discussed.
Perception of clear English fricatives
Authors: Maniwa Kazumi , Jongman Allard , Wade Travis
Published: October 2013

Two experiments investigated whether and how clear speech production enhances intelligibility of English fricatives for normal-hearing listeners and listeners with simulated hearing impairment. Fricative intelligibility in clear and conversational speech was assessed using a database of 8800 VCV ([a]-fricative-[a]) stimuli produced by 20 speakers. Babble thresholds were measured for minimal pair distinctions for 14 normal-hearing listeners and 14 listeners with simulated sloping, recruiting impairment. Clear speech benefited both groups overall; however, for impaired listeners, the clear speech effect held only for sibilant pairs. In a previous acoustic study involving the same stimuli [Maniwa, Jongman, and Wade, J. Acoust. Soc. Am. 119, 3301 (2006)], 14 parameters were measured: spectral peak location, the first four spectral moments, F2 onset transitions, spectral slopes below and above typical peak locations, pitch of adjacent vowels, overall rms amplitude, relative amplitude (frication amplitude relative to the vowel in specific frequency bands), harmonic-to-noise ratio, energy below 500 Hz, and fricative duration. Correlation analyses comparing acoustic and perceptual data indicated that a shift of energy concentration toward higher frequency regions and greater source strength contributed to the clear speech effect for normal-hearing listeners, while listeners with simulated loss seemed to benefit mostly from cues involving lower frequency regions.
Clear speech effects for vowels produced by monolingual and bilingual talkers
Authors: DeMasi Teresa , Rogers Catherine L. , Krause Jean C.
Published: October 2013

The present study investigates the hypothesis that bilinguals may produce a smaller intelligibility benefit than monolinguals when asked to speak clearly. Three groups of talkers were recorded: 13 monolingual native English speakers, 22 early Spanish-English bilinguals, with an age of onset of learning English (AOL) of 12 or earlier, and 14 later Spanish-English bilinguals, with an AOL of 15 or later. Talkers produced the target words ‘‘bead, bid, bayed, bed, bad’’ and ‘‘bod’’ in both clear and conversational speech styles. Two repetitions of each target word were mixed with noise and presented to monolingual English-speaking listeners in a six-alternative forced-choice task across two days of testing. Stimuli were also presented in quiet on two subsequent days of testing. In preliminary data from 13 listeners, the early bilinguals were slightly more intelligible in noise than the monolingual talkers, with both groups showing a similar degree of clear speech benefit. Later bilinguals were less intelligible overall and showed a much smaller clear speech benefit in noise. These data suggest that later bilinguals, but not early bilinguals, may experience a disadvantage when speaking in noise due to a reduced ability to improve intelligibility by speaking more clearly [Work supported by NIH].
Modeling lexical distinctiveness as a function of natural variations in segmental speechreading ability
Authors: Auer Edward
Published: October 2013

The ability to perceive spoken language on the basis of optical signals alone (speechread) is known to be widely distributed. Previous computational modeling studies investigating sources of speechreading variability (Auer & Bernstein, 1997) demonstrated that small variations in available segmental distinctiveness were associated with large differences in lexical uniqueness. However, these previous studies modeled the variation in available segmental distinctiveness algorithmically and not on the basis of naturally occurring variation. In the current study, behavioral experiments were performed to measure the available segmental distinctiveness for perceivers differing in speechreading ability. Twelve hearing participants, chosen to systematically vary in sentence-level speechreading ability (6 high and 6 low), identified consonants and vowels presented in consonant-vowel or consonant-vowel-consonant nonsense syllables. The two participant groups differed in vowel identification accuracy, but not in consonant identification accuracy. The groups also differed in the patterning of confusions between segments. Results will be presented from computational experiments performed to assess the effects of variation in the available segmental distinctiveness on the uniqueness of words in the language. The results will be discussed in terms of potential sources of individual variability in speechreading. [Work supported by a NIH/NIDCD R01DC04856.]
Auditory-visual speech perception: What isolated articulators contribute
Authors: Bosseler Alexis N. , Kuhl Patricia K. , Massaro Dominic W. , Meltzoff Andrew N.
Published: October 2013

The present study investigated the effects of viewing specific articulators on auditory-visual speech perception. We used a jaw-only, lips-only, jaw+lips, and full face visual stimulus paired with clear versus degraded auditory stimuli in an expanded factorial design. The unimodal and bimodal speech syllables were identified as one of five possible response alternatives (/ba/, /da/, /tha/, /bda/ or /bga/). The results indicate that both visual and auditory sources of information influenced syllable identification under the lips alone, lips+jaw alone, and whole face conditions. Performance was better described by the fuzzy logical model of perception than by an auditory dominance model or a weighted-averaging model. Overall, the results are consistent with the idea that although there may be differences in the information provided (which reflect the amount of information each articulator contributes to perception), the way in which the speech information is processed remains invariant. Work funded for the research was provided by a National Institute of Health Training in Speech and Hearing Sciences grant to the University of Washington’s Speech and Hearing Sciences Department and by a National Science Foundation Science of Learning Center grant to the University of Washington’s LIFE Center.
Dynamic cortical imaging of speech compensation for auditory feedback perturbations
Authors: Houde John , Nagarajan Srikantan , Heinks-Maldonado Theda
Published: October 2013

Understanding how auditory feedback is processed and used during speech production is a long-standing issue, one that has classically been investigated by looking at how altering auditory feedback affects speech. Recently, the advent of functional neuroimaging methods has also allowed examination of how producing speech affects the neural processes serving auditory perception. Here, whole-head magnetic source imaging (MSI) was used to monitor cortical activity as speakers responded to brief perturbations of the pitch or amplitude of their speech. Prior studies have shown that such perturbations cause compensatory responses in speech motor output. MSI recordings were acquired at the onset of feedback perturbations as the subject continuously vocalized and also when the subject passively listened to recordings of the perturbed feedback. A response to the perturbations was found around auditory cortex between 100 and 400 ms postperturbation that was enhanced while subjects vocalized, as compared to when they passively listened. The size of this response enhancement was a significant predictor of how much a subject compensated for the feedback perturbation. Time-frequency optimized adaptive spatial filtering was also used to localize cortical activations that correlated significantly with degree of compensation across subjects. [Work supported by NSF grant BCS-0349582 and NIH/NIDCD grant R01-DC006435.]
Activity in regions sensitive to auditory speech is modified during speech production: fMRI evidence for an efference copy
Authors: Zheng Zhuo , Johnsrude Ingrid , Munhall Kevin
Published: October 2013

Models of speech production postulate that, in order to facilitate rapid and precise control of articulation, the predicted auditory feedback is sent to the auditory system to be compared with incoming sensory data. If this is so, an ‘‘error’’ signal may be observed when the predicted auditory feedback and the sensory consequences of vocalization do not match. We used event-related fMRI to look for the neural concomitants of such an error signal. In two conditions volunteers whispered ‘‘ted.’’ In one of these, voice-gated noise was used to mask the auditory feedback, which should result in an error signal. Two other conditions were yoked to the production conditions (either clearly heard or masked), but were listen-only and therefore no error signal would be expected. We acquired whole-brain EPI data from 21 subjects using a fast-sparse design. Activity in the superior temporal gyrus bilaterally was significantly greater for clear than masked speech during the listen-only trials and significantly higher for masked than for clear speech in the production trials. This crossover interaction indicates that speech production results in corollary discharge in the auditory system and furthermore suggests that this corollary discharge reflects expectations about the sensory concomitants of speech acts.
Coarse classification of acoustic signals using temporal and spectral characteristics
Authors: Mennitt Daniel J. , Johnson Marty , Carneal James
Published: October 2013

Sound can be classified in many ways on many levels of detail. Coarse classification is especially desirable in situations where the expected type of acoustic sources is unknown. A reliable method is proposed to classify acoustic signals as impulsive, tonal, or broadband (e.g., gunshot, engine, and vehicle tire noise) based on statistics of the signal in the time and frequency domains. Algorithms are presented that efficiently calculate an impulsive and tonal metric, which is used to differentiate multiple acoustic sources in a noisy environment. This is applicable to multitarget tracking where sequential measurements of a target’s location must be associated to propagate the track; the acoustic attribute discriminates against targets with similar kinematic quantities. Elementary signals are subjected to the proposed classification algorithm to determine thresholds of the categories. Finally, the algorithms are shown to identify various sources from measured field data.
Towards improving the target recognition using spectral and cepstral features
Authors: Supriya M.H. , Saseendran Pillai P.R.
Published: October 2013

The identification of various noise sources in the ocean, which are generating noises that are diverse in characteristics, carried out using power spectral estimation has only limited success rates. It has been found that the errors associated with the identification process can be reduced, to some extent, if the information gathered from the power spectral estimation is supplemented with those gathered from cepstral analysis. A prototype system for identifying the targets from the target signatures generated from the noise waveforms emanating from the noise sources in the ocean has been implemented by judiciously combining the features extracted from the spectral estimation and cepstral analysis. It has been observed that the MFCC for various records vary over a range of values and in order to improve the performance of the identifier, the optimum set of values for the cepstral coefficients are synthesized by a technique quite frequently referred to as vector quantization. In this paper, the LBG (Linde, Buzo, Gray) design algorithm for vector quantization by trimming the cepstral coefficients to the nearest value has been adopted for finding out the optimum match.
A comparison study of various techniques for blind estimation of reverberation time
Authors: Fialkoff Joshua , Xiang Ning
Published: October 2013

Reverberation in a room often adds a desirable coloration to a perceived sound, but research shows that one’s ability to correctly interpret speech degrades with increased reverberation. Recently, various techniques for blind estimation of reverberation time have been suggested. Techniques such as these could prove to be indispensable tools not only for architectural acousticians, but communication engineers and audiologists as well. In this study, various techniques for blind estimation of reverberation time are implemented in the MATLAB environment. Each technique is tested using various real and simulated signals to determine its respective efficacy.
Decomposition of the time-reversal operator in the Rayleigh limit
Authors: Minonzio Jean-Gabriel , Prada Claire , Fink Mathias
Published: October 2013

Acoustic scattering analysis is an important tool in acoustic imaging and characterization with applications in non-destructive testing, medical imaging or underwater acoustics. The DORT method consists of the study of the time-reversal invariants which correspond, for a given transducers array, to the eigenvectors of the time-reversal operator or to the singular vectors of the array response matrix K. The decomposition of the scattered pressure in normal modes of vibrations allows the determination of the theoretical time-reversal invariants for different two-dimensional elastic objects such as cylinders or tubes. The N dimension problem, where N is the number of transducers, is reduced to a problem which dimension is about 2ka+1, where a is the scatterer radius and k the wave number in the surrounding fluid. This approach provides analytical expressions of the two first singular values and vectors in the Rayleigh limit, i.e. 2a smaller than the resolution cell. These results are verified experimentally and in good agreement with the original point of view: for a small scatterer, there is one dominant singular value associated with the singular vector which focuses isotropicaly on the scatterer. Some of these results can be generalized to 3-D objects such as spheres.
Passive reverberation nulling for target enhancement
Authors: Song Heechun , Hodgkiss William S. , Kuperman William A. , Sabra Karim , Akal Tuncay , Stevenson Mark
Published: October 2013

Echo-to-reverberation enhancement has been previously demonstrated using time reversal focusing when knowledge of the channel response between a target and the source array element is available. In the absence of this knowledge, direct focusing is not possible. However, active reverberation nulling still is feasible given observations of reverberation from conventional source array transmissions. For a given range of interest, the response between the source array elements and the dominant sources of boundary reverberation is provided by the corresponding reverberation from this range. Thus, an active transmission can be projected from the source array which minimizes the energy interacting with the boundaries at a given range while still ensonifying the waveguide between the boundaries. As an alternative, here we describe a passive reverberation nulling concept. In a similar fashion, the observed reverberation defines the response between the source array elements and the dominant sources of boundary reverberation at each range and this is used to drive a range-dependent sequence of projection operators. When these projection operators subsequently are applied to the received time series, reverberation can be suppressed. The improvement in target detectability is demonstrated using experimental data with an echo repeater simulating the presence of a target in shallow water.
An investigation of the use of chaotic signals in active sonar
Authors: Fenwick Alan
Published: October 2013

Many natural effects are now known to be chaotic rather than random, i.e., are generated by simple non-linear systems. The paper reports the outcome of a theoretical and experimental study to assess whether signals based on chaotic time series offer advantages in active sonar. It is noted that for conventional detection, the detailed structure of the signal is unimportant. Any advantage will come from novel effects due to interactions with the target or the environment. An overview is given of apparently novel behavior in echoes from a resonant target which were first noted in simulations and then observed in laboratory ultrasonic measurements. An explanation in terms of linear systems theory is outlined. The limitations which inhibit the use of advanced non-linear techniques for detection will be discussed and illustrated with reference to the results of analyzing data measured in an outdoor acoustic test facility.
Audiogram, body mass, and basilar papilla length: Correlations in birds and predictions for extinct archosaurs
Authors: Dooling Robert , Gleich Otto , Manley Geoffrey
Published: October 2013

The inner ear in the group of archosaurs (birds, crocodilians, and extinct dinosaurs) shows a high degree of structural similarity, enabling predictions of their function in extinct species based on relationships among similar variables in living birds. Behavioral audiograms and morphological data on the length of the auditory sensory epithelium (the basilar papilla) are available for many avian species. By bringing different data sets together, we show that body mass and the size of the basilar papilla are significantly correlated, and the most sensitive frequency in a given species is inversely related to the body mass and the length of the basilar papilla. We also demonstrate that the frequency of best hearing is correlated with the high-frequency limit of hearing. Small species with a short basilar papilla hear higher frequencies compared with larger species with a longer basilar papilla. Based on the regression analysis of two significant correlations in living archosaurs (best audiogram frequency versus body mass, and best audiogram frequency versus papillar length), we suggest that hearing in large dinosaurs was restricted to low frequencies with a high-frequency limit below 3 kHz.
Representation of particle motion in the developing midbrain
Authors: Simmons Andrea , Horowitz Seth , Tanyu Leslie
Published: October 2013

In underwater organisms such as tadpoles, both particle motion and pressure components provide important information about ambient sound sources. Using both anatomical and physiological techniques, we examined the representation of these components in the developing midbrain. Afferents from the lateral line and from the saccule both project to the medial vestibular nucleus in the medulla which, in turn, sends projections to the laminar nucleus of the torus semicircularis in the midbrain. Extracellular recordings from the laminar nucleus of tadpoles from early larval through metamorphic climax stages show robust responses to particle motion, but across a more constrained frequency range than observed in the medulla. Combined with earlier data showing good responses to the pressure component of sound sources, these data suggest that the laminar nucleus may be a site of integration of particle motion and pressure sensitivity.
Observations of phase and travel time variations of normal modes during tropical storms Ernesto and Florence
Authors: Langer Gregor , Miller James H. , Potty Gopu R. , Lynch James F.
Published: October 2013

Acoustic normal modes in shallow underwater environments are stretched and compressed due to surface gravity waves and, therefore, experience phase and travel time variations at the receiver. Using the adiabatic approximation, the arrival times of repeated transmissions will wander as a function of time. In addition, the arrivals of fully coupled modes will spread due to the presence of the surface waves [Lynch, Miller, and Chiu, J. Acoust. Soc. Am. 85, 83–89, (1989)]. Data collected during the Shallow Water 06 experiment on the continental shelf off New Jersey by five single hydrophone receiving units (SHRU) and a vertical line array/horizontal line array were analyzed. Phase-encoded signals from acoustic tomography sources with center frequencies of 224 and 400 Hz were recorded on the receiving systems. The bandpass impulse response of the waveguide was measured repeatedly over a month and the phase and travel time variations of normal modes were determined. The passing of tropical storms Ernesto and Florence during the experiment in the summer of 2006 provided very high sea states. Estimates of mode wander and spread before, during, and after passing of the tropical storms will be presented and compared to existing theories. [Work supported by Office of Naval Research.]
Uncertainty estimation in Bayesian seismo-acoustic reflection travel-time inversion
Authors: Dettmer Jan , Dosso Stan E. , Holland Charles W.
Published: October 2013

This paper presents a nonlinear Bayesian inversion for high-resolution seabed reflection travel time data, including rigorous uncertainty estimation and examination of statistical assumptions. Travel time data are picked on seismo-acoustic traces and inverted for a layered sediment sound-velocity model. Particular attention is paid to picking errors that are often biased, correlated, and nonstationary. Non-Toeplitz data covariance matrices are estimated and included in the inversion along with unknown travel time offset (bias) parameters to account for these errors. Simulated experiments show that neglecting error covariances and biases can cause misleading inversion results with unrealistically high confidence. The inversion samples the posterior probability density and provides a solution in terms of one- and two-dimensional marginal probability densities, correlations, and credibility intervals. Statistical assumptions are examined through the data residuals with rigorous statistical tests. The method is applied to shallow-water data collected on the Malta Plateau during the SCARAB98 experiment.
Bubble nucleation and cavitation in soft tissue: The initial moments
Authors: Church Charles C. , Khokhlova Vera A.
Published: October 2013

In the absence of underlying pathology, biological tissue is expected to be free of gas bubbles. In order for cavitation to occur, the necessary bubbles must be nucleated by the acoustic field. Tiny vapor-filled bubbles continuously form and dissolve in regions of very low interfacial tension. In the presence of an acoustic wave, such microbubbles will act as cavitation nuclei. The probability of nucleation increases with both temperature and rarefactional pressure. Nonlinear propagation and diffraction of high-intensity focused ultrasound (HIFU) in tissue results in the formation of shocks and asymmetric waveforms with a lower peak but longer negative pressure phase than linear analysis predicts; the presence of shocks also greatly enhances energy deposition with a correspondingly more rapid temperature rise in the focal region. The effects of these processes on nucleation rate will be assessed. Post-nucleation bubble motion will then be explored using a modified version of the Keller-Miksis equation for nonlinear bubble dynamics combined with the linear Voigt model for viscoelastic media and a three-component version of the model to simulate a layer of degraded tissue between the gas bubble and the surrounding tissue. Various cavitational phenomena will be discussed. [Work supported by NSBRI SMS00402, RFBR, and DAMD17-02-2-0014.]
Acoustic bubble simulations for biomedical applications using boundary element method (BEM)
Authors: Khoo Boo C. , Fong Siew W. , Klaseboer Evert , Turangan Cary
Published: October 2013

High intensity soundwaves, such as shockwaves and HIFU, are widely used in biomedical applications, for example, extracorporeal shockwaves lithotripsy (ESWL) and HIFU prostate cancer treatment. The high pressure in the tissue and nearby fluid often causes formation of cavitation bubbles. Our previous simulation results via BEM approach show complex bubble ultrasound interactions: in certain cases a jet is formed directed away from the nearby tissue while in others, towards it [Fong et al., Ultrasound Biol. Med., 32(6), 925–942, 2006]. In the present work, pulsed ultrasound microbubble interaction is studied using the same code to provide further understanding to the jetting behavior of the bubbles near (different) biomaterial surface which is critical to the success of tissue ablation and the minimization of auxiliary damages. Separately, we have also simulated shockwave bubble interaction using the BEM code with excellent concurrence to other compressible numerical schemes such as arbitrary Lagrangian-Eulerian and free Lagrange methods [Klaseboer et al., Comput. Methods Appl. Mech. Eng. 195, 4287–4302 (2006)] and experiments. It is suggested that the (primary) dynamic response of the bubble to soundwaves is mainly inertia controlled since compressibility of the fluid is not modeled.
The natural frequency of nonlinear oscillation of ultrasound contrast agents in microvessels
Authors: Qin Shengping , Ferrara Katherine W.
Published: October 2013

Prediction of natural frequency of oscillation of ultrasound contrast agents (UCAs) in microvessels plays an important role in UCA imaging and drug delivery. Here, the natural frequency of a microbubble in microvessels was studied in detail. Three models for blood vessel compliance have been considered, i.e., a rigid vessel, normal compliant vessel, and a stiff vessel which may correspond to the tumor-developing vasculature. Numerical results demonstrate that the natural frequency of a bubble in a rigid vessel is substantially decreased as compared to that in an unbounded field. However, within a compliant vessel, the natural frequency of bubble oscillation increases with decreasing vessel size. When a bubble with a radius of 4 m is confined in a compliant vessel (inner radius 5 m and length 100 m), the natural frequency of bubble oscillation increases by a factor of 1.7 as compared with that in an unbounded field. The natural frequency of bubble oscillation in a compliant vessel decreases with increasing values of vessel rigidity. This model suggests that contrast agent size, blood vessel size distribution, and the type of vasculature should be comprehensively considered for choosing the transmitted frequency in UCA imaging and drug delivery. [Work supported by NIH CA 103828.]
Bubble and particle interactions in constrained media
Authors: Cui Jianying , Hamilton Mark F. , Hay Todd A. , Ilinskii Yurii A. , Wilson Preston S. , Zabolotskaya Evgenia A.
Published: October 2013

Shock wave lithotripsy and high intensity focused ultrasound produce a variety of cavitation bubble interactions in confined spaces. Densely packed bubble clusters are generated that exhibit strong collective interactions. In lithotripsy, the bubble clusters themselves interact with the surface of a kidney stone. Comminution of the stone generates an accumulation of small particles that are interspersed with, and dynamically coupled to, the cavitation bubbles. Within tissues surrounding the stone, cavitation activity can occur in urinary ducts and blood vessels, constrained by channel walls. We are developing a systematic approach to modeling coupled bubble dynamics in clusters, amidst particles, near surfaces, and in tubes. The model is based on Lagrangian and Hamiltonian formulations of the dynamical equations for interacting bubbles. The initial formulations model the acoustically driven pulsation and translation of clustered spherical bubbles in a free field [Ilinskii et al., J. Acoust. Soc. Am. 121, 786–795 (2007)]. This model has been augmented to include interaction with spherical elastic particles. Interaction with rigid surfaces, including confinement by tubes with triangular, square, and hexagonal cross sections, has been modeled via the method of images. The relevant model equations will be presented and discussed, and representative simulations will be shown.
Generation of acoustic waves in the eye via cavitation during photoablation of corneal tissue
Authors: Hastings Mardi C.
Published: October 2013

During LASIK and other refractive correction surgeries, the shape of the cornea is modified by removal of tissue with high energy laser pulses. The laser beam deposits enough energy over a small spot size (approximately 1 mm diameter) to create a cavitation event from localized heating. Multiple pulses are delivered at different locations on the cornea to remove tissue selectively and reshape its surface in effort to minimize optical wavefront aberrations. Cavitation with each pulse can generate an acoustic wave that propagates within the eye and potentially damage sensory cells in the retina. A mathematical model was created to investigate this phenomenon and understand the effects of laser spot size and pulse repetition frequency on characteristics of the acoustic wave. Motion associated with the cavitation event was treated as a point source on the surface of a spherically shaped eye globe. A spatial map of internal acoustic pressure amplitudes was then created; results indicate that operational parameters can be adjusted to help prevent deleritous effects of cavitation-induced stress waves on the retina during refractive correction surgery.
Dynamics of nonlinear piston-generated and vertical-array-generated foci
Authors: McDonald B. Edward , Walker Shane C. , Kuperman William A.
Published: October 2013

Recent work using a vertical array of linear sources to produce a distant virtual source array [Walker et al., J. Acoust. Soc. Am. 120, 3007 (2006)] motivates investigation of the possibility of generating a nonlinear virtual source array. First, the nonlinear focal properties of a single piston as a function of amplitude and piston aperture are examined using the NPE [McDonald and Kuperman, J. Acoust. Soc. Am. 81, 1406 (1987)] and compared with results from the KZK equation [J. Acoust. Soc. Am. 119, 3618 (2006)]. Next, results are shown for a phased vertical array of spherical explosive sources, which produce Mach stemlike structures as the nonlinear component waves interact. Finally, the fully three-dimensional problem of multiple piston beams focusing in a predetermined pattern is described. [Work supported by the Office of Naval Research.]
Physical models of transducer coupling in dense arrays
Authors: Kotsidou Kassiani , Thompson Charles
Published: October 2013

In this work we will examine the coupling between direct sound radiators. It will be shown that at low frequencies, the mutual impedance between a pair of transducers is analogous to that of two simple sources. Hence the magnitude of their interaction will be inversely proportional to their separation distance. The phase is proportional to the propagation time between a transducer pair. The implication of this result is explored in the design of a densely packed arrays, will be examined.
Acoustic coupling of drum-set cymbals
Authors: Spencer Edmund , Wheeler Paul
Published: October 2013

When playing the standard drum set there is a definite audible coupling between the crash cymbal and the splash cymbal. The purpose of this paper was to evaluate this coupling by studying the spectral signature of each cymbal. Separate recordings were made of a 16-in. (40-cm) thin dark crash cymbal and a 10-in. (25-cm) splash cymbal in an anechoic chamber. Spectra Plus software was used to extract the spectral signature of each cymbal. The two cymbals were then placed in proximity with each other and new recordings were made, striking each cymbal in turn. New combined spectral signatures were extracted showing a change in signature for each cymbal due to cross coupling with the other cymbal. The signatures of sympathetic vibrations produced by the unexcited cymbals were then extracted from the combined spectral signatures using MATLAB software. This experiment provided a better understanding of the nature of the coupling between cymbals and provided the needed data for future study of the actual coupling mechanism.
Application of cochlear analysis techniques to finding percussive events in electro-acoustic music
Authors: Anderson Mills John
Published: October 2013

Electro-acoustic music is a style of music for which often the pressure signal itself is the only consistent, objective representation of the music. A project has been undertaken at The University of Texas to automatically extract audio properties from recordings of electro-acoustic music to create a new, visual representation, and the first property chosen to extract is a measure of the ‘‘single damped percussive events’’ (SDPEs) found in a piece of music. In order to accurately measure the performance and motivate the development of an SDPE finding algorithm, 26 human participants ranked percussive and near percussive sounds according to how much the sounds were like an SDPE and marked at what point the sounds were no longer an SDPE. The results of this data collection show that rise time is the most important percussive cue and that tonal content, spectral filtering, and ring modulation have little effect on judging a sound to be an SDPE. The preliminary algorithm has been tested against the human performance and the results are presented here. The ultimate goal of the algorithm is to produce a ‘‘percussivity profile’’ of a piece of electro-acoustic music.
Sinusoidal wavelet transforms for pitch estimation of music signals
Authors: Pathak Charu , Das V. G. , Kumari V. Prem , Pyra V. Prem , Das V. G. , Kumari V. Prem , Pyara V. Prem
Published: October 2013

Pitch is related to fundamental frequency in an audio signal. It is a perceptual measure and depends on the auditory system. Discrete Fourier transforms which are most commonly used provide same resolution through the entire range of frequencies and give the output as an average over the entire bin. Resolution of human auditory system varies logarithmically which maps just as the multiresolution analysis based on wavelet transforms. Sinusoidal wavelet transforms are proposed here to detect two continuously occurring signals to a good resolution both in frequency and time. The accuracy can be increased to a desired value by increasing the number of scaling factors used. The technique can be used for note identification and musical instrument recognition through pattern classification.
Surface waves in the nocturnal boundary layer
Authors: Talmadge Carrick L. , Waxler Roger , Di Xiao , Gilbert Kenneth E.
Published: October 2013

Experimental observations are presented for pulse propagation in several different types of nocturnal boundary layers. It is shown that, in all cases, a strong surface wave arrival is present, even when other arrivals are weak or absent. Thus, it is argued that the surface wave arrival is a ubiquitous feature of sound propagation in the nocturnal boundary layer. Theoretical reasons are given to support the validity of the argument. Some implications for practical applications are discussed. [Research supported by the U. S. Army TACOM-ARDEC at Picatinny Arsenal, New Jersey.]
Time-domain boundary conditions in atmospheric acoustics
Authors: Ostashev Vladimir E. , Collier Sandra L. , Marlin David H. , Wilson D. Keith , Aldridge David F. , Symons Neill P.
Published: October 2013

In atmospheric acoustics, formulation of a reactive, time-domain boundary condition (TDBC) at the ground surface is a challenging problem since many commonly used models of the ground are noncausal and have a slowly decaying response. A correctly formulated TDBC can significantly simplify finite-difference time-domain simulation of outdoor sound propagation, which is a rapidly developing field in computational acoustics. In the present paper, approaches are developed that enforce causality and improve computational efficiency of TDBCs. First, an approach is developed that allows one to derive a causal TDBC for any impedance model of the ground. A Pade approximation is used to represent the characteristic admittance. Then, using fractional derivatives, a causal TDBC is formulated. This method is illustrated by formulation of TDBCs for the Zwikker-Kosten (ZK) and Attenborough models of the ground. Furthermore, by approximating the fractional derivatives as a summation of decaying exponentials, an effective recursive algorithm for implementation of these TDBCs is outlined. Second, it is demonstrated that approximating the known TDBC for the ZK model as a summation of decaying exponential functions significantly improves the computational efficiency of the method.
Impulse propagation in the nocturnal boundary layer: Experimental observations outdoors with a vertical array
Authors: Waxler Roger , Talmadge Carrick L. , Di Xiao , Gilbert Kenneth E.
Published: October 2013

As observed experimentally by Chunchuzov et al. [J. Acoust. Soc. Am. 88, 455 (1990)], impulsive signals propagating in the downward refracting atmospheres typical of the nocturnal boundary layer have a canonical long-range form: they consist of multiple arrivals followed by a low frequency tail. Theoretical arguments that such behavior is canonical and an identification of the low frequency tail with the ground-coupled surface mode have been recently presented [J. Acoust. Soc. Am. 117, 2532 (2005)]. In November 2006, pulse propagation experiments were performed at night on farmland in the Mississippi River Delta. The source used was a propane cannon and the receiver was a 10 meter tower with 16 equally spaced microphones microphones located 1.6 km downwind from the source. Meteorological data was collected from three sensor stations mounted on the tower, six attached to a tethersonde line and a sodar device. Results from these experiments will be presented and discussed.
Acoustic propagation in the vicinity of an isolated building
Authors: Alberts W. C. Kirkpatrick , Noble John M.
Published: October 2013

The literature regarding urban acoustics has often been concerned with the propagation of sound through street canyons typical of residential areas in large cities, while sparsely built suburban areas have received little attention. As a fundamental case of acoustic propagation in suburban areas, the study of the influence that an isolated building has on propagating sound is a necessity in order to determine the processes (wall impedance, ground impedance, diffraction, diffusion, etc.) required to model the interaction of propagating acoustic waves with an isolated building. As such, an experimental and theoretical investigation of this fundamental case is currently being performed on isolated buildings of construction typical to North American suburban areas. Experimental results, using both continuous and impulsive excitation sources, for propagation near a single story, gabled roof building typical of some suburban areas will be presented.
Coherence function of a wave propagating through intermittent turbulence
Authors: Ostashev Vladimir E. , Wilson D. Keith , Goedecke George H.
Published: October 2013

An important characteristic of atmospheric turbulence is intermittency, i.e., the tendency of turbulence to occur in bursts of activity. Intermittency can affect the statistical moments of a sound wave propagating in a turbulent atmosphere. To address this problem, in this paper a quasi-wavelet (QW) model of intermittent temperature fluctuations is developed. In the model, QWs become less and less space filling as their sizes decrease. Using this model, formulas for different statistical characteristics (variance, kurtosis, and 3D spectrum) of intermittent temperature fluctuations are derived. Then, the obtained 3D spectrum is used to calculate the coherence function of a sound wave propagating in a turbulent atmosphere. The coherence function is one of the most important statistical moments of a sound field needed in many applications. The effects of intermittency of turbulence on the coherence function are studied. The calculated coherence function is also compared to that obtained by a different approach, in which the structure parameter of refractive index fluctuations is assumed to be a random function along the sound propagation path. The results obtained in this paper can be used in other problems, e.g., to study coherence of seismic waves for line-of-sight propagation through intermittent geological heterogeneities.
The academic family tree of Katherine Safford Harris
Authors: Bell-Berti Fredericka , Raphael Lawrence J. , Kewley-Port Diane
Published: October 2013

At Haskins Laboratories Kathy Harris lead a research team of engineers, programmers, technicians, ENT physicians, and fellow scientists to study speech production. As the reputation of this innovative research program grew, students, post-doctoral fellows, and visiting scientists from many universities and international laboratories came to join Kathy in this effort. Her contributions to training doctoral students grew when she became a faculty member at the CUNY Graduate Center. Kathy Harris was a pioneer role model, especially, but not exclusively, for women scientists. Her enthusiasm and dedication to science attracted a host of students and young scientists who have gone on to academic research careers in speech communication. Kathy nurtured her students, always ready to listen and encourage, guiding but never pushing them through their degrees, and always keeping sight of the person.
F. V. Hunt and acoustics at Harvard University
Authors: Wright Wayne M.
Published: October 2013

Soon after his arrival from Ohio as a graduate student of G. W. Pierce in 1925, Frederick Vinton Hunt established himself as a Harvard scientist to be considered seriously. He submitted two doctoral theses, joined the faculties of physics and applied physics, and in 1940 graduated his first doctoral student, Leo Beranek. He founded and directed the war-time Harvard Underwater Sound Laboratory for the Navy, and he mentored a total of 70 graduate students and postdoctoral fellows prior to his retirement in 1971, a year before his death. While the acoustics tradition at Harvard effectively ended with Ted Hunt’s departure, a number of individuals that he mentored have developed and supported acoustics programs elsewhere in academia. Others have made significant contributions in government and industry, and several have followed his lead in contributing much to the Acoustical Society of America. Beyond his personal impact, his legacy includes 29 recipients of the Society’s F. V. Hunt Postdoctoral Fellowship, the first of which being Steven Garrett (1978–79, now at Penn State), and the recent production under ASA auspices of a CD that makes generally available the 61 Technical Memoranda from Hunt’s Acoustics Research Laboratory.
Jiri Tichy and the Penn State—Brigham Young University connection
Authors: Sommerfeldt Scott D. , Leishman Timothy W.
Published: October 2013

Jiri Tichy held the position of Chair of the Graduate Program in Acoustics at Penn State University for many years, and oversaw significant growth in the acoustics program there over those years. During that time, Tichy also had a significant number of graduate students, both at the MS and PhD levels. This poster will attempt to identify most, if not all, of those students, as well as where they went in their careers. In addition, two of Tichy’s graduate students both migrated to Brigham Young University (BYU). BYU’s acoustics history includes both Carl Eyring and Harvey Fletcher, who both spent some of their careers at BYU. Over the past decade, the BYU acoustics program has enjoyed a resurgence, brought about largely by an influx of Penn State graduates. This has also led to a strengthened connection between Penn State and BYU, and these connections and interrelationships will be outlined in the poster.