bluuebunny/crossref_metadata_2025 huggingface dataset:
Underwater acoustic measurements with a flying wing glider
Authors: D’Spain Gerald L. , Zimmerman Richard , Jenkins Scott A. , Luby James C. , Brodsky Peter
Published: October 2013

Liberdade, a new class of underwater glider based on a flying wing design, has been under development for the past 3 years in a joint project between the Marine Physical Laboratory, Scripps Institution of Oceanography and the Applied Physics Laboratory, University of Washington. This hydrodynamically efficient design maximizes the horizontal distance traveled between changes in buoyancy, thereby minimizing average power consumed in horizontal transport to achieve ‘‘persistence.’’ The first fully autonomous glider of this class, ‘‘XRay,’’ was deployed and operated successfully in the Monterey Bay 2006 experiment. Communications, including real-time glider status reports, were accomplished using an underwater acoustic modem as well as with an Iridium satellite system while on the surface. The payload included hydrophone array, with 10 kHz per channel bandwidth, located in a sonar dome along the leading edge of the 6.1-m-span wing. Narrowband tones from 3.0 to 8.5 kHz were transmitted from a ship-deployed controlled underwater source. During the glider’s flight, lift-to-drag ratios (equal to the inverse of the glide slope) exceeded 10/1. However, specific flight behaviors that deviated from this efficient horizontal transport mode allowed for improved detection and localization by the hydrophone array. [Work sponsored by the Office of Naval Research.]
High-resolution repeat bathymetric mapping using a mid-size autonomous underwater vehicle
Authors: D’Spain Gerald L. , Zimmerman Richard , Chadwell C. David , Zumberge Mark , Blum John , Orcutt John , Driscoll Neal , Dingler Jeff , Kent Graham , Banon Hugh H. , Openshaw Graham , Jeanjean Philippe
Published: October 2013

Shipborne bathymetric surveys south of Santa Barbara, CA indicate that massive slope failures have occurred along the northern flank of the Santa Barbara Basin. This region is seismically active and has the highest sedimentation rates along the California coast due to rapid erosion of the Transverse Ranges. A set of geodetic monitoring systems is being developed to study the character and deformation of the ocean bottom in this region, particularly that of a prominent east-west trending crack aligned with the head scarp of one of the underwater landslides. One component is a high-resolution repeat bathymetric mapping system composed of a multibeam sonar mounted inside a Bluefin 21 AUV. Navigation to the decimeter level is provided by an inertial navigation system and accurate depth sensor, and by a long baseline (LBL) acoustic transponder system previously developed to monitor tectonic plate motions. The quality of the data, particularly that from the high-precision LBL system, is enhanced significantly by the decrease in the radiated acoustic and vibration noise of the AUV to levels at, or below, ocean background noise levels through modifications to the AUV propulsion system. [Work sponsored by British Petroleum and the Office of Naval Research.]
Graph-theoretic sonar detection performance of maneuverable vehicles in variable propagation environments
Authors: Bilik Igal , Krolik Jeffrey
Published: October 2013

This work addresses the problem of passive acoustic target detection using a maneuverable unmanned underwater vehicle (UUV) equipped with a towed line array. The objective is to assess target detection performance as a function of vehicle maneuverability and environmental variability. Detection performance is evaluated by mapping the search region onto a graph with nodes that constrain the vehicle trajectory and edge weights determined by the local detection probability. Vehicle maneuverability is constrained by limiting the maximum turn angle at each node. The UUV trajectory that maximizes the probability of at least one target detection can then be determined using the computationally efficient Dijkstra algorithm. Increased maneuverability improves detection performance given known environmental variability since the optimal trajectory is able to visit more locations with favorable environmental conditions. The optimal detection performance of a maneuverable array with relatively short array lengths is compared to that of a nonmaneuverable vehicle with a longer array. It is shown that maneuverability can be even more advantageous than array length given sufficiently variable environmental conditions. The impact of uncertainty and/or mismatch of the assumed environmental variability is also studied as a function of vehicle maneuverability and towed-array length. [This work support by ONR 321SP.]
Exact solutions of the compressible inverse elasticity problem
Authors: Barbone Paul E. , Oberai Assad A.
Published: October 2013

In elastic modulus imaging or quantitative elastography, tissue stiffness is inferred from an (ultrasonically) measured displacement field. Doing so requires the solution of an elastic inverse problem. We present several exact solutions of the compressible inverse elasticity problem: Given the (possibly transient) dispalcement field measured everywhere in an isotropic, compressible, linear elastic solid, and given density ρ, determine the Lamé parameters λ(x) and μ(x). The cases we treat are: (a) for μ(x) known a priori, find λ; (b) for λ(x) known a priori, find μ; (c) neither λ(x) nor μ is known a priori, but Poisson’s ratio ν is known; (d) neither λ(x) nor μ nor ν is known a priori. We present several example applications including 2D and 3D problems, quasistatic and time dependent displacement fields. Many of the results here are drawn from P.E. Barbone and A.A. Oberai [‘‘Elastic Modulus Imaging: Some exact solutions of the compressible elastography inverse problem,’’ Phys. Med. Biol. (in press)].
Progress in breast vibro-acoustography: Imaging breast lesions
Authors: Alizad Azra , Whaley Dana H. , Greenleaf James F. , Fatemi Mostafa
Published: October 2013

Vibro-acoustography is an imaging method based on the sound emitted due to the harmonic motion of tissue induced by the radiation force of focused ultrasound. This paper presents recent progress in vibro-acoustography of human breast. Matching vibro-acoustography and mammography images are acquired using a combined mammography/vibro-acoustography machine. Images of various types of breast masses are investigated and their characteristics features are compared. The study includes malignant masses, benign masses such as fibroadenomas, cysts, calcified lesions, and surgical scars. Image features, such as lesion borders, interior texture, and speculation pattern, are studied. Vibro-acoustography images demonstrate that calcified masses normally show sharp borders, benign noncalcified masses have smooth texture, and, in some cases, malignant masses are characterized with spiculation. These results, which are based on the data collected from an ongoing study, indicate that the above-mentioned image features may be used for differentiation of breast masses. It is noted that more data from a larger population are needed to establish the results in a statistical sense. [Work supported by NIH Grant EB-00535 and Grant BCTR0504550 from the Susan G. Komen Breast Cancer Foundation. Disclosure: Parts of the techniques used here are patented by MF and JFG.]
Measurement of the anisotropy of the backscatter coefficient of formalin-fixed myocardial tissue
Authors: Yang Min , Krueger Todd , Holland Mark , Miller James
Published: October 2013

The objective of this study was to measure the backscatter coefficient of myocardial tissue as a function of the angle of insonification relative to the predominant myocardial fiber direction. Eight cylindrical formalin-fixed ovine left-ventricular myocardial specimens were immersed in a water bath and insonified with a 5 MHz center frequency ultrasonic transducer. Backscattered ultrasonic data were acquired from the mid-myocardium of each tissue specimen over a full rotation. The backscattered data obtained for each angle of insonification were compensated for the effects of attenuation and diffraction to obtain measurements of the backscatter coefficient. Values for the backscatter coefficient at 5 MHz exhibited marked anisotropy, ranging from (17±14)×10−4 cm−1 Sr−1 when insonified perpendicular to the predominant myofiber orientation to (1.2±0.7)×10−4 cm−1 Sr−1 when parallel (mean±standard deviation).
Classification of trabecular bone tissue through acoustic scattering
Authors: Denis Max , Thompson Charles , Chandra Kavitha
Published: October 2013

In this work, the scattering of acoustic waves from a three-dimensional trabecular bone is considered. The trabecular bone volume is represented as a binary medium comprised of fluid and solid phases. A perturbation expansion is performed in terms of gauge functions based on the density and compressibility contrast between the constituent components of the bone tissue. Internal resonance and multiple scattering effects are considered. In our simulations, trabecular bone samples having normal and osteoporosis condition will be examined. It is shown that the interior features of the media can be extracted by analysis of the forward scattered field. Of particular interest are features of anisotropy and frequency dependence of scattering field. The potential utility of this method for diagnosing osteoporosis stages in trabecular bone tissue is discussed.
Analysis of acoustical nonlinear measures for aircraft flyover data
Authors: James Michael , Downing Micah , McInerny Sally Anne , Gee Kent
Published: October 2013

Numerous analysis techniques have been proposed as means of characterizing acoustical nonlinearities in high-thrust engine noise. These include probability distributions for the pressure and the time derivative of the pressure (i.e., the gradient), the skewness and kurtosis coefficients of the pressure and its time derivative, bispectral analysis, and Howell-Morfey plots. In this presentation, a number of these analysis techniques are applied to acoustic data recorded from several different military jet flyovers. The results presented here emphasize the need for high bandwidth, large signal-to-noise ratio measurements.
Comparison of artificial neural network structures to identify military impulse noise
Authors: Bucci Brian A. , Vipperman Jeffrey S.
Published: October 2013

To monitor the production of military impulse noise in the area of military installation a classifier is being developed to identify military impulse events from other noise sources. In previous work [B. A. Bucci, J. S. Vipperman, J. Accoust. Soc. Am. 119, 3384 (2006)], efforts were made to identify military impulse noise from other noise sources using a multi-layer perceptron neural network. The network used scalar input metrics (kurtosis, crest factor, spectral slope, and weighted square error) computed from recorded wave forms. In an extension to this effort, various types of neural network classifiers utilizing wavelet coefficients and cepstral coefficients as inputs are currently being tested and compared. These network types, which have proven successful in similar applications, include multi-layer perceptrons, radial basis function network, self-organizing maps, and recurrent networks. The networks are trained on an increased library of waveforms as compared to the previous effort. The goal of this effort is to also produce a classifier continuous operation rather than analyzing selected recordings as in the previous effort. [This research was supported wholly by the U.S. Department of Defense, through the Strategic Environmental Research and Development Program (SERDP).]
Demonstration of a highly directional acoustic source
Authors: Wilson Preston S. , Wright Wayne M. , Hamilton Mark F.
Published: October 2013

Highly directional light sources such as flashlights, spot lights, and lasers are common objects well known to most people. In contrast, a highly directional acoustic source, or, in other words, a source of sound that is audible in only a very narrow region of space, is far less common. Most people have never experienced such a source, and the phenomenon is not found in nature. A highly directional source of sound known as a parametric array is used underwater for sonar applications, but the frequency (pitch) of the sound is often above the hearing range for human listeners. Similarly, highly directional, focused sound sources are regularly used in medical applications, but, again, the frequency is too high to be heard. The narrowness of the acoustic beam cannot be experienced by human listeners. Recently, parametric array technology has been commercialized for use in air at frequencies in the human auditory range. These devices produce very narrow beams of audible sound. When pointed at one person, who can be listening contentedly, the sound is inaudible to another person only a few feet away. Such a device will be demonstrated and the basic physics behind its operation will be explained.
Demonstration of nonlinear acoustic landmine detection: Hysteresis effects observed in a soil-elastic plate oscillator
Authors: Korman Murray S. , Pauls Kathleen E. , Genis Sean A. , Sabatier James M.
Published: October 2013

In nonlinear acoustic landmine detection the vibration interaction of the top-plate of the buried plastic landmine with the adjacent soil is a subject of interest due to the strong nonlinear coupling. Donskoy discovered the significance of using nonlinear vibro-acoustic two-tone tests to help find buried relatively compliant landmines at certain nonlinearly generated combination frequencies; and that false alarms were reduced due to minimal nonlinear interactions over relatively rigid buried objects. Later, work by Sabatier showed that certain nonlinear experimental results involving tuning curves and profiling at a large number of combination frequencies from two-tone tests (in buried plastic anti-tank inert landmine experiments) revealed that the nonlinear effects were similar to the mesoscopic/nanoscale nonlinear elastic behavior observed in geomaterials like sandstone. Here, an apparatus called the soil-plate oscillator is used to model the nonlinear interaction of a thin clamped vibrating acrylic plate with a small column of dry sifted soil supported over it. Measurements of the effects of tuning curves taken at increased amplitude acoustic drive amplitude (exhibiting softening) can be explained if hysteresis effects (characteristic of the mesoscopic nonlinear) interaction are taken into consideration. Lissajou patterns of the driving force vs. displacement also reveal hysteresis effects. [Work support by ONR.]
Visualizing acoustic resonances in quasi 2D solids
Authors: Gladden J. R.
Published: October 2013

Acoustic resonances in solid objects are easily detected through the sound that they radiate, but the vibration patterns are hard to visualize because the frequencies are high and amplitudes are low. I plan to demonstrate a system using a birefringent solid which is acoustically driven at resonances frequencies. The birefringence allows strain fields to be visualized as bright and dark bands when the resonator is placed between crossed optical polarizing plates and illuminated from behind. Using a strobe light as the light source with the frequency closely matched to the resonance frequency slows the time scale of the acoustic cycle so it can be easily followed by the human eye.
Live demonstration of a physical model of the active cochlea
Authors: Jovic Tina , King Curtis , Rabbitt Richard
Published: October 2013

An active physical model of the cochlea was constructed to mimic the nonlinear amplification carried out by the human cochlea. The model includes hair-cell cilia-like sensors to measure the local velocity of the fluid, and electromagnetic actuators to actively feed energy back into the motion. The model is outfitted with an electromagnetic shaker (mimicking the eardrum) to deliver complex waveforms to a piston (mimicking the stapes). Since the model is much larger than the cochlea, its best response frequencies are shifted down in the spectrum. The most interesting responses are obtained when music is recorded in stereo, digitally processed, and replayed into the model. One channel is frequency shifted to match the best frequencies of the model while the other channel is played acoustically without modification. This allows the listener to observe the motion of the cochlear partition in temporal synchrony with hearing the original soundtrack. A live demonstration of the apparatus in response to pure tones, speech, and music will be presented under both passive and active conditions. [Work supported in part by NIDCD R01 DC04928.]
Planetary exploration using acoustic instrumentation: The past and the future
Authors: Towner Martin C.
Published: October 2013

To date only a couple of planetary missions have deployed acoustic instruments, primarily intended to probe acoustic environments (such as listening for thunder) rather than to investigate physical properties. The recent Huygens probe mission to Saturn’s moon Titan is the first to carry our more involved measurements, but still using relatively simple instruments as an altimeter and to estimate the speed of sound. I briefly review some of the acoustic instruments that have been flown on previous space missions, and the environments they have had to deal with, and discuss in more detail the Huygens results. Spacecraft designers are by nature conservative, tending to use older, more reliable technology, but capable instruments are still possible, and it is hoped to show how small simple acoustic sensors can contribute a lot to the scientific understanding for relatively few resources. Forthcoming opportunities are also considered, based on current exploration plans.
The Huygens probe Surface Science Package acoustic instrument: Results at Titan
Authors: Zarnecki John C.
Published: October 2013

The European Space Agency’s Huygens probe, when it landed on the surface of Titan, Saturn’s largest moon, on January 14, 2005, carried the first active acoustic sensors to be deployed on another cosmic body. The Surface Science Package contained a simple sonar (operating at 14.7 kHz) and a speed of sound sensor (operating at 1 MHz). The design and operation of the sensors will be described. Despite being optimized for the case of landing on a surface of liquid hydrocarbons, the landing on a solid surface still produced valuable data. The former sensor obtained echoes from Titan’s surface during the last 90 m of the descent. Interpretation of these data will be discussed in terms of surface properties, such as terrain topography and possible physical nature, around the landing site. Probe landing speed was also derived with high precision. The speed of sound instrument operated in the lower 11 km of the atmosphere. These data have been used to constrain the methane content of Titan’s atmosphere to approximately 2% at 10 km rising to about 3.5% at lower altitudes.
Alien soundscapes: Acoustics on Titan, Venus, Mars, and Earth
Authors: Petculescu Andi , Lueptow Richard
Published: October 2013

In January 2004, the general public was able to listen to the sounds of an alien world for the first time. The world was Saturn’s moon, Titan, and the sounds were audio recordings taken during the descent of the Huygens probe. In this paper, calculations of sound speed and attenuation in the atmospheres of Titan, Venus, Mars, and Earth are obtained using a new molecular relaxation-based model. Vertical atmospheric profiles of sound speed and attenuation are calculated at a frequency of 15 kHz. The profiles are obtained using currently available data of temperature, pressure, and density. The sound speed profiles mirror the differences in atmospheric layering. The absorption profiles are comparatively smooth for Mars, Titan, and Earth while Venus has a noticeable attenuation dip between 40 and 100 km. During descent of a probe, acoustic quiet zones occur when sensing sound is produced by a low-frequency simple source near the surface. The frequency dependence of sound speed and attenuation is calculated at the surfaces of the four bodies. The effect of acoustic atmospheric filtering on an audio sample transmitted in the four planetary environments is also addressed. [Work funded by NASA.]
A small logging sensor station for infrasonic detection of bolides to complement a camera network
Authors: Towner Martin C. , Bland Philip A.
Published: October 2013

A small simple logging station is described that is intended to search for and detect the infrasonic signature of an incoming meteor. This is part of activities to support a fireball camera network currently being deployed in the Nullarbor desert in Western Australia. Camera networks are constrained in the time that they can be active by their required viewing conditions; for example they are not generally active during daylight hours or when the weather is overcast. As a complementary approach, investigation has been carried out concerning the detection of meteors by alternative means, most notably by investigating their infrasonic and electromagnetic signature. This system consists of a small logger, an infrasonic detector, a VLF detector, and other supplementary sensors, independently powered by solar panels, and with a satellite modem for data return.
Naive performance on interaural time difference discrimination with high-frequency amplitude-modulated tones
Authors: Zhang Yuxuan , Wright Beverly A.
Published: October 2013

Humans are sensitive to changes in interaural time differences (ITDs) in high-frequency sounds with fluctuating amplitude envelopes. However, despite noted large individual differences in high-frequency ITD discrimination ability, to date, most investigations of this performance have employed only a few, typically experienced, listeners. Thus, it is not clear whether the data thus obtained are representative of the general, naive, population. Here, ITD discrimination thresholds with high-frequency amplitude-modulated tones were examined in nineteen listeners, all naive to psychoacoustic testing. The large range of performance across these listeners accommodated the collective data previously reported, but was not fully illustrated by any single previous investigation with a small sample size. For these naive listeners, ITD discrimination performance at high frequencies, 1) was much worse than that at low frequencies, 2) was better with a slower (0.15 kHz) than a faster (0.3 kHz) modulation rate with a 4-kHz carrier, and 3) did not differ between a lower (4 kHz) and higher (6 kHz) carrier frequency with a 0.3-kHz modulation rate. These data help establish high-frequency ITD discrimination performance in the general population, and may aid in the interpretation of performance measured in situations where testing time is limited. [Work supported by NIH.]
Within- and across-listener performance variability in discrimination of interaural time and level differences
Authors: Zhang Yuxuan , Wright Beverly A.
Published: October 2013

The ability to discriminate changes in interaural time differences (ITDs) and interaural level differences (ILDs) varies markedly both within and across individuals. Such variability has been frequently noted, but rarely systematically investigated. Here, both forms of variability, expressed in terms of coefficients of variation (mean divided by standard deviation), were examined across a variety of ITD and ILD conditions in a total of 84 naive listeners. Three consistent patterns emerged. First, across-listener variability was relatively constant across ITD and ILD discrimination, suggesting that this variability might be determined by factors common to the processing of both cues. Second, compared to across-listener variability, within-listener variability was larger for the ITD conditions but smaller for the ILD conditions, suggesting that, within individuals, ITD processing may have a higher level of internal noise than ILD processing. Third, stimulus frequency (ranging from 0.3 to 6 kHz) and stimulus type (pure tones and sinusoidally amplitude modulated tones) had little influence on either type of variability, suggesting that variability was determined by cue-dependent, rather than stimulus-dependent mechanisms. The systematic nature of these variability patterns illustrates that examination of variability can provide important insights into the processing of interaural cues. [Work supported by NIH.]
A stable capacity limit in interaural time-difference discrimination across training and individual listeners.
Authors: Wright Beverly A. , Zhang Yuxuan
Published: October 2013

An interesting learning pattern was previously observed for ITD-discrimination training with a 500-Hz tone. While the highest of the twelve threshold estimates obtained each day from each listener (n=8) decreased significantly over days, the lowest did not. However, the lowest values averaged ∼6 microseconds, raising the question of whether they represented actual discrimination ability or resulted from random walks in the adaptive testing procedure. In an attempt to address this question, all twelve estimates of each listener were ordered from lowest to highest and the effect of training was examined separately for each rank. There was no improvement for the four lowest ranks, which ranged from ∼6–25 microseconds. These values represent 33% of the data, a seemingly unlikely rate for random walks. In addition, in naive listeners (n=32), despite marked inter-individual variation in the average and highest thresholds, the lowest thresholds were constant across listeners. Though these analyses do not preclude the potential contribution of random walks within this data set, they keep open the possibility that the invariance in the lowest thresholds through training and across listeners was not an artifact of the adaptive procedure, but rather reflects a stable capacity limit in ITD processing. [Work supported by NIH.]
Using auditory saliency to interpret complex auditory scenes
Authors: Duangudom Varinthira , Anderson David V.
Published: October 2013

In this paper, a computational model for predicting preattentive, bottom-up auditory saliency is proposed. The model determines perceptually what in a scene stands out to observers. The vision equivalency of this is visual saliency as defined by Koch and others [Itti et al., IEEE Trans. Pattern Anal. Mach. Intell. 20(11), 1254–1259, (1998)]. The proposed auditory saliency model is based on suppression or promotion of different feature maps obtained using auditory spectro-temporal receptive fields. The auditory saliency model does well in predicting what is salient for some common auditory examples and produces results that match well with results obtained from psychoacoustic experiments. Additionally, experiments performed to evaluate the model found that there is a strong correlation between auditory scenes chosen as salient by the model and scenes that human subjects selected as salient. [Work supported by NSF.]
Comparison of relative and absolute judgments of speaker size based on vowel sounds
Authors: Walters Thomas C. , Gomersall Phil A. , Turner Richard E. , Patterson Roy D.
Published: October 2013

Judgments of speaker size are largely determined by two acoustic variables: glottal pulse rate (GPR) and resonance scale [i.e., vocal tract length (VTL)]. Both variables change with age (or height), but the rate is governed by different factors. The interaction of the variables was previously measured using absolute judgments of speaker size [D.R.R Smith and R.D. Patterson, J. Acoust. Soc. Am. 118, 3177–3186 (2005)]. The resulting size surface (over the GPR-VTL plane) bends down outside the normal range. In this paper, a method is developed for deriving the surface using size-discrimination data. In a two-alternative forced-choice experiment, listeners compared sequences of vowels scaled in GPR and VTL to represent speakers with slightly different sizes; they were required to choose the interval with the smaller speaker. Comparisons about a point in the plane reveal the gradient vector, and the vectors across the GPR-VTL plane can be integrated to estimate the size surface. The results indicate that the size surface would be essentially planar if determined by size discrimination. This indicates that relative size judgments are different from absolute size judgments, probably because some source knowledge is required for the absolute judgements. [Research supported by the UK Medical Research Council (G9900369).] a)Currently at the Gatsby Computational Neuroscience Unit, Alexandra House, 17 Queen Square, London, WC1N 3AR, UK.
Implementing synthesis control using timbral adjectives
Authors: Disley Alastair C. , Howard David M. , Hunt Andrew D.
Published: October 2013

The authors have previously developed theories of relationships between timbral adjectives and spectral features, with a goal of developing a synthesizer using timbral adjectives as synthesis controls [Disley et al., J. Acoust. Soc. Am. 119, 3333 (2006) abstract only]. These theories have been applied to a software-based additive synthesizer developed in the freeware Pure Data environment, in conjunction with practicing musicians and music technologists. Realistic yet highly configurable synthesis as a foundation for timbral manipulation is permitted by the use of harmonic envelopes derived from successive Fourier analysis of real-world samples. Theories of timbral adjectives’ relationships to spectral and time-domain features can be mapped onto synthesis primitives. User feedback can then be used in an iterative process to refine existing theories and develop new controls unique to an individual’s personal understanding of one or more timbral adjectives. The qualities of the resulting synthesis system and some revised theories of timbral adjectives are both discussed.
Dynamics of glottal ariflow
Authors: Krane Michael
Published: October 2013

The traditional assumptions concerning airflow in the glottis during vocal fold vibration are assessed. An equation of motion describing the dynamics of glottal airflow, and which explicitly includes terms due to separation point motion, wall displacement, skin friction, and glottal jet inertia, is derived. The relative order of magnitude of each of these terms is assessed using experimental data. It is shown that there are two temporal regimes during each cycle of vibration. The first holds when the glottis is just opening and just closing, in which wall motion and friction are important. In the second regime, when the glottis is wide open, the traditional assumptions hold as long as glottal jet inertia is negligible. If jet inertia is dynamically relevant, the aerodynamics is unsteady. If not, then effects such as the Coanda effect are dynamically insignificant. Evidence for the dynamic relevance of glottal jet inertia is presented. [Authors gratefully acknowledge support from NIH Grant 2 R01 DC005642-04A1.]
Physical mechanisms of phonation onset: The role of flow instabilities
Authors: Zhang Zhaoyan , Neubauer Juergen , Berry David
Published: October 2013

Current models of phonation exhibit a series of flow phenomena such as an oscillating flow separation point, the Coanda effect, and vortex shedding downstream of the glottis. While accounting for such phenomena significantly increases the computational load and may influence many aspects of phonation, the influence of such airflow features on phonation onset is still unknown. In a two-dimensional continuum model of phonation with a fixed flow separation point, a recent analysis showed that, in the absence of acoustics, the primary physical mechanism of phonation onset was the matching of the flow stiffness (i.e., the intraglottal airflow pressure) with the elastic stiffness of the vocal folds, resembling common observations of human phonation. Thus, the oscillation of the flow separation point may be merely a consequence of the unsteady motion of the vocal folds, with only a minor influence on phonation onset at low frequencies. With a natural frequency much higher than the phonation frequency, flow instabilities such as vortex shedding may also only play a secondary role in determining the conditions of phonation onset (apart from being responsible for flow separation and the transglottal pressure drop), at least for normal phonation. Further experiments are needed to clarify the relative importance of these flow features on phonation onset.
Vortex shedding and the voice source
Authors: Howe Michael S. , McGowan Richard S.
Published: October 2013

The voice source is primarily an acoustic dipole produced by the fluctuating drag on the vocal folds [Zhao, Zhang, Frankel et al., J. Acoust. Soc. Am. 112, 2134–2146 (2002)]. In this paper the unsteady drag is determined theoretically in terms of the vorticity shed from the vocal folds. The principal source of acoustic energy is glottal-jet vorticity lying within an axial distance downstream of the glottis of less than about the glottal width. The vortex drag dipole is equivalent to the volume velocity source traditionally assumed to be located at the glottis. In addition, there exists a true, but weaker fluctuating volume source associated with volumetric changes of the vocal folds region. The relationship between the voice source dipole and sibilant fricative dipoles will be discussed. Our findings will be presented in a largely qualitative manner, so that the few equations used in the presentation can be understood physically. [Work partially supported by NIDCD-004688.]
Aerodynamically-based parametric description of the noise envelope in voiced fricatives
Authors: Barney Anna , Jackson Philip J. B.
Published: October 2013

In voiced fricatives, the radiated sound is composed of a harmonic component associated with the vibrating larynx and a noise component generated at a constriction in the oral cavity. The sound from the two sources interacts in a nonlinear way to produce a noise signal with an amplitude envelope modulated at the fundamental frequency of voicing. While voiced fricatives synthesized as a linear combination of harmonic and noise components are identifiable, it is recognized that the inclusion of the modulation improves the perceived naturalness of a synthesized token. The depth of modulation of the radiated noise, for a range of aerodynamic and acoustic variables, was measured experimentally using a dynamic mechanical model of the larynx and vocal tract. Glottal excitation arose from driven shutters representing the vocal folds; frication noise was produced by an orifice plate with a sharp-edged obstacle downstream. Based on the empirical data, a parametric description was developed to predict the depth and phase of amplitude modulation of the noise from the aerodynamic and acoustic conditions.
Continuous infrasonic recording within the Utah regional seismic network
Authors: Pankow Kris , Burlacu Relu , Hayward Chris , Stump Brian
Published: October 2013

In May 2006, the University of Utah Seismograph Stations, as part of a larger consortium, installed an infrasound array east of the Salt Lake Valley (NOQ). Infrasound can be thought of as seismology in the air focusing on subaudible acoustic signals in the frequency band from 0.01 to 20 Hz. Advantages of installing an infrasound array in northern Utah include a proximity to solid earth sources (mine blasts and earthquakes) and the possibility of incorporating the data into a regional seismic network. The primary application of infrasound is in identification of explosions detonated at or near the solid earth-atmosphere boundary. However, to fully utilize the infrasonic data, better understanding of infrasonic source characteristics and propagation is needed. Goals of the infrasound installation at NOQ include (1) use of local ground truth information to assess the role of infrasound in source identification; (2) classifying properties of the infrasound signal by source type; (3) assessing the time varying characteristics of infrasound propagation; and (4) incorporating the infrasound data into seismic source location. In this paper, we will show examples of both seismic and infrasound signals from ground truth events and we will discuss aspects of data processing.
Modeling the spatial coherence of seismic surface waves at short propagation distances
Authors: Wilson D. Keith , Ostashev Vladimir E.
Published: October 2013

Scattering from small, random inhomogeneities in the ground (such as rocks and voids) diminishes the spatial coherence of seismic waves, much as turbulence in the atmosphere diminishes spatial coherence of propagating sound waves. In this paper, modeling of seismic spatial coherence for surface waves propagating over short distances (roughly 50 m to 1 km) and at relatively high frequencies (greater than approximately 1 Hz) is considered. The random inhomogeneities are distributed broadly in size and are described with a quasi-wavelet (QW) model. For simplicity, we consider propagation of a 2-D scalar wavefield. Scattering from an individual QW is first calculated using a single-scattering approximation. Then, the contributions from all randomly placed QWs, including all size classes, are cross-correlated to find the spatial coherence of the total wavefield. As an example, we consider modeling of seismic coherence at a site in the Mojave Desert with random basaltic inhomogeneities surrounded by sand. The impact of coherence loss on direction-finding with geophone arrays is discussed.
Mapping the middle Paleozoic through three-dimensional seismic attributes in the central Arkoma Basin, Oklahoma
Authors: Brinkerhoff Alonzo R. , Keach Bill , McBride John , Ritter Scott , Felt Vince
Published: October 2013

Seismic attribute analysis and mapping, reveals that Hunton Group strata do occur in the central and southern Arkoma Basin of eastern Oklahoma and that they were not completely removed by pre-Woodford erosion as previously believed. Well and isochron data through the Viola-Woodford interval (Ordovician-Late Devonian) show isolated ∼40 m thick lenses of Hunton rocks, on average measuring 3 km in diameter. This distribution could be explained in two ways; 1) Hunton occurrences could represent isolated erosional remnants reflecting incomplete removal of the Hunton Group during Middle Devonian time (pre-Woodford unconformity) or 2) due to karsting and collapse of stratigraphically lower units (Arbuckle Group?), lenses of Hunton rocks could have sagged into sinkholes where they were preserved below regional base level. A combination of these models may be necessary to account for areas where we see thinning both in the Woodford and Viola, suggesting that a Hunton lens is structurally lowered due to karsting, but due to its erosionally resistive nature, the lens forms a depositional high, causing the Woodford to thin over it.
Effects of model discretization on the statistics of model parameters in nonlinear inverse problems
Authors: Ganse Andrew A. , Odom Robert I. , Ganse Andrew A. , Odom Robert I.
Published: October 2013

An inverse problem is the estimation of a continuous model function given a finite set of data points. In most geophysical problems, due to data noise and lack of complete geometric coverage, this problem is intractable analytically so we parameterize the continuous model and solve as a regularized parameter estimation problem. Coarsening the discretization of an ocean bottom model is one way to stabilize the otherwise ill-conditioned problem; this is sometimes called regularization by discretization. But by setting the resolution of the model estimate prior to the inversion in this way, one also affects the model estimate’s statistics, due to the inherent tradeoff between model resolution and uncertainty. This relationship is well understood for linear problems, but resolution and uncertainty in nonlinear inverse problems remains an active area of research. In nonlinear problems the probability distributions of the model parameters are not Gaussian, and so with Monte Carlo methods we explore the relationship between the magnitude of non-Gaussian features in the model probability, the discretization of the model, and the aliasing of its parameters. [Work partially supported by ONR.]
Benchmarking echoes from an object in an ocean waveguide with bottom roughness
Authors: Stotts Steven A.
Published: October 2013

A complex k-plane two-way coupled mode model including both trapped and continuum effects can be used to benchmark acoustic reverberation in an ocean waveguide. In addition, scattering from both bottom roughness and an object in the waveguide can be evaluated simultaneously in a consistent approach. To derive the benchmark, a two-dimensional problem for the recent Reverberation Workshop, held in Austin, TX in November 2006, was selected. The problem has a constant sound speed Pekeris waveguide and is used as the waveguide model for developing the current benchmark. The two-dimensional problem is derived from a vertical slice through a three-dimensional environment and only considers scattering in the vertical plane. The source is a Gaussian beam with a center frequency of 250 Hz. The source and receiver are mono-static in range and the waveguide has a mean depth of 50 m and includes bottom roughness obtained from a single realization of a defined roughness spectrum. For the benchmark calculation, an object (in addition to the bottom roughness) is introduced into the water column. Propagation of the signal to and echo from the object in the water column also includes bottom scattering effects.
Seabed characterization and transmission loss estimation from geoacoustic inversion using a towed array
Authors: Goh Yong Han , Huang Chen-Fen , Gerstoft Peter , Hodgkiss William S.
Published: October 2013

The goal of geoacoustic inversion is to estimate environmental parameters from measured acoustic fields from, e.g., a towed array. Though the inversion results have some uncertainty, inversion is an efficient technique to estimate environment parameters. Based on the a posteriori probability density of environment parameters obtained from inversion, we perform statistical estimation of transmission loss (TL) and generate a 90% credibility level envelope or uncertainty band for the TL. This uncertainty band accounts for the inherent variability of the environment not usually contained in sonar performance prediction model inputs, and presents a useful probabilistic description of the environments variability. Towed arrays are advantageous to fixed systems as they are easy to deploy and the moving ship enables estimation of spatially variable seabed properties. The approach is demonstrated with data obtained from the MAPEX2000 experiment conducted by NATO Undersea Research Centre (NURC) in the Mediterranean Sea in November 2000.
Energy and vorticity analysis (EVA) experiment 2006
Authors: Ghosh Deep , Schmidt Henrik
Published: October 2013

Low frequency (2–15 kHz) monostatic and multistatic target scattering data was acquired at subcritical and supercritical angles from three targets: a composite cylinder, a composite sphere and an air filled GOATS sphere. A TOPAS parametric source with 40 kHz primary and 2–15 kHz secondary frequency was used to insonify the targets for the monostatic and multistatic near field measurements. The monostatic experiment was carried out using a 16 element Vertical Line Array (8 kHz). The multistatic experiment was carried out using a CW Doppler source at 17 kHz with a 4 element receiver array deployed from the ships well. Differential GPS data was recorded for accurate track recording. The ship roll, pitch and heading were also recorded. The multistatic near field measurements were carried out using a light PVC dome of height 1.7 m and diameter 3.7 m. Nine broadband hydrophones served as the receiver array which could be rotated by an electric motor. Aspect of −145 degrees to +145 degrees was covered in each case. The data will be processed to study the near field scattering from targets which would help in better target classification and detection in near field region. [Work supported by NURC, NRL and Leonardo.]
A long-term field soil survey by acoustic techniques: Part II. Nonlinear acoustics
Authors: Lu Zhiqu
Published: October 2013

Soils are nonelastic and nonclassic nonlinear materials. They present loading-history-dependent, end-point memory, and hysteretic properties, which distinguish themselves from elastic materials such as intact crystal and fluids. Based on recent development in nonclassic nonlinear acoustic theory, a phase shift method is used to determine the hysteretic nonlinearity parameter of a field soil. In this method, the phase shift between the transmitter and receiver caused by increasing the sound level is measured and used to curve fit the equation of state that takes into account hysteresis, and to calculate the nonlinearity parameter. In a long-term survey, the hysteretic nonlinearity parameter, sound speed, temperature, moisture, soil suction, and rain precipitation are measured and their relations are studied. It is found that the nonlinearity parameter is much more sensitive than sound speed to the climate change. Soil suction is the predominant factor that affects the nonlinearity parameter. Unlike sound speed, the hysteretic nonlinearity parameter is sensitive to the variation of temperature.
Multiple means of conveying information through sound: Comparisons of environmental sounds and spoken language processing using converging methodologies
Authors: Dick Frederic , Leech Robert , Cummings Alycia , Borovsky Arielle , Saygin Ayse Pinar
Published: October 2013

Environmental sounds are increasingly viewed as an attractive nonlinguistic analog for studying meaningful speech in that they can convey referential—or at least associative—information about objects, scenes, and events that unfold over time. However, environmental sounds also differ significantly from speech along other perceptual and informational parameters. These cross-domain similarities and differences have proved useful in uncovering the perceptual and cognitive divisions of labor in the developing and mature brain. Our group has directly compared environmental sound and spoken language understanding in a series of behavioral and neuroimaging studies with infants, typically and atypically developing children, healthy adults, and aphasic patients. In general, our results suggest that environmental sounds and language share many of the same processing and neural resources over the lifespan. [This research is supported by the National Institutes of Health and the Medical Research Council.]
Influence of auditory information on auditory-visual speed discrimination
Authors: Heller Laurie M.
Published: October 2013

Auditory information can exert a strong influence on multimodal perception. In the experiments described here, a video of a ball rolling in depth was paired with the sound of a ball rolling. The speed of the balls’ roll in the video was independently varied from the speed of the balls’ roll in the soundtrack. Total duration was held constant so that the auditory cues to speed were ongoing spectro-temporal features of the rolling sounds. In a 2IFC comparison, observers indicated which ball seemed to roll faster. In half of the trials the near-threshold visual and auditory speed information was consistent, e.g., both the video and sound sped up between the first and second interval. Performance improved as much as would be predicted by a linear model. On the other half of the trials in which the auditory and visual information were inconsistent, performance declined accordingly. [Work supported by NSF.]