bluuebunny/crossref_metadata_2025 huggingface dataset:
Improving the efficiency of the comprehensive acoustic simulation system Navy standard reverberation model.
Authors: Weinberg Henry , Keenan Ruth E.
Published: October 2009

Research projects that use supercomputers and real-time applications for at-sea exercises would benefit from more efficient code. This paper describes various approaches that significantly reduced the run time of the comprehensive acoustic simulation system (CASS) Navy standard reverberation model. These include computer upgrades, parallel processing, and reconfiguring code. For example, typical CASS run times of two 3-GHz computers differed by a factor of 10 because the faster computer had more efficient memory. Three types of parallelization were also tried. The easiest to implement used a platform that contained numerous blades with eight processors per blade. Reverberation runs were split along receiver bearing angles with several bearing angles per processor. The second parallelization attempted fine grain segmentation. This proved inefficient exchanging data between processors until the GRAB eigenray model was restructured. The third approach, OPENMP, has the advantage of using the same code on computers without multiple processors. Of course, there will be no improvement in efficiency. A disadvantage is that OPENMP is difficult to master. Improved hardware and multiple processors alone were insufficient to provide adequate results for many applications. The approach described here requires reverberation and clutter predictions along numerous receiver beams in seconds.
A practical approach towards a timely seafloor interaction database.
Authors: Arvelo Juan I. , Zeddies David , Ellison William T.
Published: October 2009

A seafloor database of physics-based parameters may be considered an ideal resource. However, geoacoustic inversion to a model accurately describing the sediment structure, sub-bottom inhomogeneities, interface roughness, and anisotropy is still a very challenging research topic. While such geoacoustic inversion challenges are resolved, a more practical approach toward the generation of a timely seafloor interaction database is sorely needed. This practical approach must offer the flexibility to accommodate any physics-based and empirical model, direct measurement, and geoacoustic inversion from all research and operational sonars. It must also offer consistency with other seafloor-related databases, sufficiency to be useful to any sonar model, and completeness to model sonar systems across a wide frequency range. Empirical seafloor scattering models have a limited number of parameters to fit all measurements across grazing angle and frequency, while the most complete physics-based models have too many parameters for high-confidence geoacoustic inversion. Therefore, a more practical worldwide seafloor database must also offer enough flexibility to accurately reconstruct the seafloor reflection and scattering functions with a minimum number of parameters. Finally, this approach must quickly arrive at an unambiguous unique solution. Such an approach will be described and demonstrated. [This effort was supported by SPAWAR.]
Target echo and clutter calculations, including time spreading using normal-mode group velocities.
Authors: Ellis Dale D.
Published: October 2009

The shallow-water normal-mode reverberation approach [D. D. Ellis, J. Acoust. Soc. Am. 97, 2804–2814 (1995)] can be extended to handle the echo from a target or discrete clutter objects. Normal modes are used to handle the propagation, and ray-mode analogies are used to handle the echo and scattering. The time spreading of the echo can be approximated using the modal group velocities. This description for the time spreading is approximate, but the computations are quite efficient, since the normal modes need only be calculated at one frequency. The target can be point-like and mode functions can be used, or the target can be considered more extended and the mode amplitude envelopes can be used. The formulation will be presented, along with a number of calculations based on problems from the ONR Reverberation Modeling Workshops. [Work supported in part by ONR, Code No. 321OA.]
Reverberation and scattering measurements from seabed clutter features using an autonomous undersea vehicle.
Authors: Holland Charles W. , Nielsen Peter L. , Hollett Reginald
Published: October 2009

Acoustic reverberation in littoral ocean waveguides is often controlled by small-scale seabed heterogeneities. Thus, validation of reverberation models and development of realistic simulations require measurements of those scales. Clutter features for mid-frequency active sonars span scales from order 1–1000 m. The smaller scale seabed features O(1–10)m, however, are not generally represented in bathymetric data, even from modern hull-mounted multibeam systems. One promising tool for isolation and quantitative measurement of small-scale seabed features is an AUV with a source (800–3500 Hz) and towed array. Recent measurements from the Clutter09 experiment in the Straits of Sicily show that O(1–10)m scale seabed features (e.g., carbonate chimneys on mud volcanoes) are resolved and can be quantified. [Work supported by the Office of Naval Research OA321 and the NATO Undersea Research Centre.]
Scattering from superspheroidal acoustic objects.
Authors: Feuillade Christopher
Published: October 2009

The extended boundary condition technique of Waterman [J. Acoust. Soc. Am. 45, 1417–1429 (1969)] has been used to study scattering from extended axisymmetric acoustic objects. These objects are formed using the mathematical function for a “super-ellipse” [i.e., (x/a)s + (z/b)s=1, where s=2n, n=1, 2, 3,…] and revolving around the z-axis. For s=2, the object is a spheroid with aspect ratio α=b/a. As s increases, the shape of the object approaches a right circular cylinder of radius a and length 2b. The method allows the scattered field to be accurately determined for all azimuthal angles as a function of frequency. The method is applied to the case of air-filled objects in water, which has importance for the interpretation of acoustic scattering from oceanic objects such as air-bubbles, the swim bladders of some fish, and zooplankton. It is found that the frequency increases with α, exactly as predicted using a geometrical method by Weston, and increases in a relatively minor way with $s$. In addition, the method shows that the monopole resonance, which leads to a spherically symmetric scattering distribution, continues to dominate low-frequency scattering even for cylindrically shaped, air-filled objects with an aspect ratio up to α=40 and s=32.
A numerical study of rough interface reverberation suppression, clutter elimination and target resonance excitation in heterogeneous media with single channel iterative time reversal.
Authors: Ying Yingzi , Ma Li , Sun Bingwen
Published: October 2009

The presence of echo returns from the rough interface of two layered medium, and the clutter of volume scattering hinders the detection of target buried in heterogeneous media. The situations are often raised in ultrasonic breast tumor diagnosis and underwater acoustic buried mine detection. This work investigates the application of monostatic single channel iterative time reversal in mitigating the difficulties with a numerical study. Simulations based on pseudospectral finite-difference time-domain method are performed with a sphere buried in the heterogeneous media of lower layer, a transmitter is situated at the upper homogeneous domain, and the interface position is normally distributed. A wideband signal is launched to initiate the process, and the time-reversed echo received at same position is emanated as renewed interrogation pulse for next iteration. Some field snapshots are taken and the echo is recorded in each iteration. The results illustrate as the number of iteration increases, small volume scattering is eliminated, and rough interface reverberation is suppressed relatively. The echoes will converge to a narrowband waveform corresponding to an object’s dominant resonance mode. The detection of target is achieved by exploiting this important acoustic signature. [Work supported by the CAS Innovation Fund.]
Three-dimensional reverberation modeling.
Authors: Sullivan Edmund J. , Godoy Carlos
Published: October 2009

Previously, reverberation modeling at sonar and torpedo frequencies was based on spectral factorization, which does not allow correct broadband, non-zero Doppler simulation in real time for a multi-channel receiver. This paper presents a new approach which avoids these limitations. Instead of transmitting the pulse itself, the method transmits a superposition of many copies of the pulse, each with a random amplitude and phase. This “noiselet” mimics the point-scatterer method without requiring a prohibitively large number of scattering points. We refer to it as the early randomization method (ERM). The propagation model used, the GRAB ray model, contains the bathymetry information, enabling the ERM to produce a statistically realistic reverberation field with a minimal number of rays. The computational load increases linearly with the number of receiver elements instead of with its cube, since there is no power spectral density matrix to factor. Since the randomness is introduced directly into the noiselet, the ERM is not limited to a particular statistical model, allowing non-Gaussian cases to be treated. Previously, this approach has shown excellent results for the two-dimensional, range-dependent case. Here, the method is generalized to also allow cross-range dependence. Comparisons with the CASS/GRAB model are shown.
Undergraduate acoustical engineering programs at the University of Hartford.
Authors: Celmer Robert D. , Vigeant Michelle C.
Published: October 2009

The University of Hartford has two undergraduate engineering programs in the area of acoustics: (1) the Bachelor of Science in Mechanical Engineering (BSME) with Acoustics Concentration and (2) the Bachelor of Science in Engineering with a major in Acoustical Engineering & Music. The first curriculum is part of a BSME degree program that has required courses in vibration as well as engineering acoustics since the 1960s. The Acoustical Engineering & Music degree is a unique program that was instituted in 1976, where applicants must have the equivalent math and science background required of all engineering students and also must successfully pass the entrance requirements of the Hartt School (University of Hartford’s music conservatory)—including the audition. Both programs encompass the same engineering vibrations and acoustics courses, as well as the same acoustics projects sequence. Alumni of both undergraduate programs have successfully obtained positions in consulting (architectural and environmental) audio product and A/V design, musical instrument design, hearing- and psychoacoustic-related design, noise control, as well as pursued graduate degrees. The use of real world industry-sponsored acoustic projects for engineering design courses throughout the curriculum will be described, as well as the programs’ continuous improvement plan and accreditation status.
Education in acoustics and noise control: A liberal arts perspective.
Authors: Cheenne Dominique J.
Published: October 2009

An education in acoustics and noise control is traditionally provided by engineering and/or graduate schools; however, since its inception in 1998 the Acoustics Program of Columbia College Chicago has graduated 99 students with a liberal arts background; 71 were hired by consulting firms in acoustics & noise control and by manufacturers, 65 are still employed in the field, 8 went on to graduate school, and 1 was recently voted into the “40 under 40” list of outstanding professionals by Consulting Specifying Engineer Magazine. Our program currently offers 14 undergraduate courses in acoustics and it draws upon the college’s resources for calculus, physics, technical writing, management, accounting, architecture, and programming courses. We are in the second year of a scholarship program with the Institute of Acoustics at Tongji University, and we recently hosted the Highway Traffic Noise seminar from the National Highway Institute. Besides well-equipped test laboratories and a very wide array of computer modeling tools, a vinyl album cutting lathe was recently added to the program’s inventory and starting in 2010, our students will be required to demonstrate that they have the skills to prepare for, schedule, and execute a very complex task that leaves no room for errors.
The University of Kansas architecture and architectural engineering programs offer focused coursework in architectural acoustics, electro-acoustics, and noise control.
Authors: Coffeen Robert C.
Published: October 2009

Courses relating to architectural acoustics, architectural noise control, mechanical and electrical noise control, and fixed installation electro-acoustic systems are presented by the architecture program of School of Architecture, Design, and Planning and by the architectural engineering program of the Department of Civil, Environmental, and Architectural Engineering, School of Engineering. This presentation will describe the courses taught by the author which have guided approximately 30 architecture and architectural engineering students plus a few electrical engineering students into professional acoustical consulting and sound system contracting. Courses taught in the 500–700 series include architectural acoustics, electro-acoustic systems, listening to architecture, senior design II acoustics emphasis, architectural acoustics for architects, and acoustic and theatrical design considerations for performance spaces. In addition, the flexible master of arts in architecture program works well for students entering the architecture program with an undergraduate degree in another field and desiring to have a career in acoustical consulting. To generate interest in acoustics, portions of several architecture and architectural engineering courses introduce building acoustics to first and second year students.
Graduate studies in acoustics at Purdue University.
Authors: Davies Patricia , Bolton J. Stuart , Li Kai Ming , Strickland Elizabeth , Wodicka George
Published: October 2009

The acoustics research and academic programs at Purdue can be divided into five broad categories: biomedical acoustics, engineering acoustics and noise control, physical acoustics and wave propagation, speech and hearing sciences, and acoustics in arts. There are 50 faculty from across 16 departments involved in various aspects of acoustics [http:/www.purdue.edu/research/phase]. The architectural engineering program has only very recently been started at Purdue, within the Civil Engineering, but there is a long history of Purdue graduates, particularly those in engineering, working in fields related to architectural engineering. One of the strengths of Purdue acoustics is this rich environment where students can study a broad range of topics in various disciplines each focused on different aspects of acoustics. Collaborations between engineering, liberal arts, psychology, and life science are a common theme in this community. An overview of the program is given but aspects of the program most closely related to architectural engineering will be described in more detail.
Graduate Program in Architectural Acoustics at the School of Architecture, Rensselaer Polytechnic Institute.
Authors: Xiang Ning , Jaffe Christopher
Published: October 2009

Established in 1998, the Graduate Program in Architectural Acoustics at Rensselaer’s School of Architecture has grown rapidly. The program offers both masters and doctoral degrees in a stimulating academic and research atmosphere. Applicants come from a variety of disciplines, including those with bachelor-level degrees (B. Arch., B.S., or B.A.) in Architecture, Music, Engineering, Audio/Recording Engineering, Physics, Mathematics, Computer Science, Acoustics, Electronic Media, Theater Technology, or related fields. The core curricula include Architectural Acoustics, Sonics Research Laboratory, Engineering Acoustics, Applied Psychoacoustics, and Communication Acoustics. Since its inception, the program has awarded more than 65 masters degrees and four doctorates. A majority of the program’s graduates have developed careers in acoustics consulting. The emphasis of the program’s curricula, its preparation for serving architectural acoustics consultants and professionals, and the research strategy at both the MS and Ph.D. degree levels will be presented.
Classifying bowhead whale call types using linear discrimination function analysis and neural networks.
Authors: Mathias Delphine , Thode Aaron M. , Blackwell Susanna B. , Green Alice , Kim Katherine H. , Otte Kristin , Tennant Sara , Greene Charles R. , Macrander Michael
Published: October 2009

Bowhead whale calls are typically divided into five categories: upsweeps, downsweeps, U and N shaped undulated calls, and complex. The frequency range, duration, and details of the frequency modulation of these calls vary considerably, even within the same call type, creating difficulties when using matched-filtering or spectrogram correlation methods. A manually reviewed test dataset has been assembled that contains examples organized by call category and signal-to-noise ratio. Using a combination of contour tracing techniques, various features were extracted, including slope, curvature, number of inflection points, and the time of the first inflection point normalized by duration. Both linear discriminant functions and a feed-forward neural network were applied to discern appropriate decision boundaries for optimum statistical classifiers. The use of linear discriminant functions resulted in a 70% good classification for all classes except for the n-shaped calls. The neural networks improved the performance to 81% for upsweeps and downsweeps but had trouble classifying calls with significant curvature. A partial explanation for the classification difficulties stems from subjective definitions of what constitutes an inflection. Results of applying the trained classifiers to bulk data collected in 2008 will be presented. [Work supported by Shell Exploration and Production Company.]
Large-scale evaluation of automated detection and localization of bowhead whale calls in the Beaufort Sea.
Authors: Thode Aaron M. , Mathias Delphine , Nations Christopher S. , McDonald Trent L. , Macrander Michael
Published: October 2009

An automated procedure has been developed for automated detection and localization of bowhead whale sounds with arbitrary frequency-modulated tones and applied to 2008 data collected from 41 directional autonomous seafloor acoustic recorders deployed over a 280-km swath in the Beaufort Sea. The procedure has seven sequential stages: an incoherent spectral band detector, an interval estimator, a feature extractor, a feed-forward neural network classifier, a stage to flag common calls among recorders, bearing extraction, and final localization. The three-layer neural network has ten hidden-layer units and uses 20 features extracted from the spectrogram classifying signals as either whale calls or other sounds. Manual analysis was conducted on recordings from six non-consecutive days chosen to span a variety of seismic activity levels. The first 12 h of each day yielded 141 796 true calls and 1.15×106 other signals that were used to train the network, with 60% of that data used to adjust the weights and 40% used to evaluate convergence. The performance of both the neural network stage and the complete tracking algorithm on the remaining 12 h of manually-analyzed data from each day will be presented. [Work supported by Shell Exploration and Production Company.]
Developing acoustical criteria for rodent housing facilities.
Authors: Lefkowitz Kimberly , Bruce Robert , Arellano Jessica , Burgess Travis , LeBlanc Stacy , Granger Arnold J. , Pesek Andrew T. , Pham Dzung X. , Bammerlin David
Published: October 2009

Medical researchers often use mice and rats for numerous procedures. In typical rat housing rooms, there can be as many as 200 rats for an investment of $800,000 and in typical mouse rooms, as many as 2570 mice for an investment of $10 million. Do the sound and ultrasound exposures of these animals interfere with the medical research objectives of the scientists? Research has shown that high-noise levels have an effect on the physical and psychological responses of rodents. In order to eliminate this factor from influencing the medical experiments, criteria limiting noise and ultrasound in animal-housing facilities are needed. Mice have a hearing range of 1000–91 000 Hz, rats from 200 to 76 000 Hz, and other rodents can hear well above the human threshold. This makes creating a standard even more important because the majority of the frequencies perceived by rodents, including frequencies in which they communicate, are not perceptible to humans and therefore cannot be easily assessed. This study considers typical environments where these animals are housed, the levels at which mice are effected by noise and ultrasound, and the existing guidelines in non-US countries. Preliminary noise and ultrasound criteria are presented.
Seismic oceanography: Low-frequency acoustical imaging of oceanic fine-structure.
Authors: Holbrook W. Steven , Schmitt Raymond W.
Published: October 2009

Seismic oceanography, the processing of low-frequency (10–200 Hz) marine reflection data with an emphasis on water-column reflections, has opened up new ways of visualizing thermohaline finestructure. Studies to date have produced stunning images of fronts, eddies, water mass boundaries, and internal waves. As it approaches its sixth birthday as a discipline, seismic oceanography is entering a critical stage of development. An early rush to document the physical basis for the reflections and to catalog images in different oceanic environments is yielding to an effort to extract useful, trustable, and quantitative information on physical oceanographic processes from the images. Here we review progress to date and point to key areas of current and future works. Promising areas of research include emerging techniques to quantify internal wave energy and turbulence dissipation from seismic images, the acquisition of industry SO data, and the production of three-dimensional and time-lapse images of finestructure. A principal challenge for the future is the merging of synthetic and field seismic data with realistic physical models of oceanic temperature/density structure, calculated at the dense horizontal and vertical spacings needed to simulate the seismic data.
Population density imagery of migrating herring shoals by ocean acoustic waveguide remote sensing.
Authors: Gong Zheng , Andrews Mark , Tran Duong , Cocuzzo Daniel , Dasgupta Saumitro , Jagannathan Srinivasan , Bertsatos Ioannis , Symonds Deanelle , Chen Tianrun , Pena Hector , Patel Ruben , Godoe Olav Rune , Nero Redwood W. , Jech J. Michael , Makris Nicholas C. , Ratilal Purnima
Published: October 2009

Ocean acoustic waveguide remote sensing (OAWRS) is a bistatic multibeam wide area sonar system that enables unaliased monitoring of fish populations over ecosystem scales. This allows us to quantify the formation processes of vast shoals of Atlantic herring (Clupea harengus) containing hundreds of millions of individuals, imaged during the Autumn 2006 spawning season. Areal population density estimation requires calibration of the low-frequency target strength of an individual shoaling herring. This is estimated from experimental data acquired simultaneously at multiple frequencies in the 300–1200-Hz range using (1) the OAWRS system, (2) areal population density calibration with several conventional fish finding sonar systems (CFFS), (3) fish length distributions obtained from trawl samples, and (4) local low-frequency transmission loss measurements. High spatial-temporal co-registration was found between shoals imaged by OAWRS and concurrent CFFS line transects, which also provided fish depth distributions. The mean scattering cross-section of an individual shoaling herring is found to exhibit a strong dependence on frequency in the OAWRS range, which is consistent with resonant scattering from an air-filled swimbladder. We show that a rapid transition from disordered to highly synchronized behavior occurs as the herring population density reaches a critical value, after which an organized group migration occurs.
Efficacy of using multiple acoustic systems to quantify Atlantic herring (Clupea harengus) aggregation metrics before and after fishing events.
Authors: Stockwell Jason D. , Weber Thomas C. , Jech J. Michael , Baukus Adam J. , Salerno Daniel J.
Published: October 2009

The use of midwater trawls to harvest Atlantic herring (Clupea harengus) in the Gulf of Maine has been a controversial topic for many years. A majority of the concern revolves around the potential physical disruption of Atlantic herring aggregations and the potential impact on ecological processes and other industries (e.g., other fisheries and eco-tourism) that rely on these aggregations. Preliminary acoustic data collection in fall 2008 using a combination of Simrad ES60 echosounders (38 and 120 kHz) and a Simrad SP90 omni-directional sonar (20–30 kHz) showed promise for quantifying herring aggregation metrics. In this presentation, we report on a pilot study conducted in the summer of 2009 that uses these acoustic systems to quantify and describe herring aggregations before and after midwater trawling with a pair of fishing vessels. We used a systematic grid design to survey an area continuously for 24 h both before and after pair trawl fishing over multiple fishing trips. We report on the efficacy of using acoustic systems to quantify the potential impacts of fishing on herring aggregations and discuss the next steps to fully evaluate these potential impacts at spatial and temporal scales relevant to the fishery.
Measuring suspended sediment concentrations and flow velocities using multibeam sonar.
Authors: Simmons Stephen M. , Best Jim L. , Parsons Dan R. , Keevil Gareth M. , Oberg Kevin A. , Malzone Chris , Johnson Kevin K. , Czuba Jonathan
Published: October 2009

Modern data handling and storage technologies facilitate the logging of the large quantity of water-column backscatter information received by multibeam sonars. Methods of using these data to derive estimates of the mass concentration and flow velocities of suspended sediment flow structures have been developed. The results obtained by the application of these methodologies to data collected at the confluence of the Parana and Paraguay rivers in Argentina and the confluence of the Mississippi and Missouri rivers in the United States will be presented. An analysis of those data in conjunction with a set of experimental data collected in a large-scale test facility will be also given. The applicability and limitations of the use of multibeam sonar for deriving suspended sediment concentrations will be discussed. By enabling the simultaneous measurements of suspended sediment concentration, flow velocities, and bathymetric data, multibeam echo-sounders are demonstrated to be a versatile tool for the surveying of the various components relating to the transport of sediment in fluvial systems.
Use of a multibeam sonar to characterize fish aggregations in the northern Pacific.
Authors: Stienessen Sarah C. , Weber Thomas C. , Wilson Christopher D.
Published: October 2009

Acoustic observations to describe small-scale spatial patterns or aggregations of fish have traditionally been made in two dimensions using vertical echosounders. Recently, multibeam sonars have been utilized as a tool to study the three-dimensional structure of fish aggregations. This study describes small-scale spatial patterns of juvenile walleye pollock, Theragra chalcogramma, with data collected using a calibrated ME70 multibeam sonar. The ME70 has reduced side-lobes and a very high dynamic range, which allow better characterization of the water column backscatter than typical multibeam systems. For this study, the sonar was configured with a 120 deg swath composed of 31 narrow bandwidth beams, ranging from 70–120 kHz. Data were collected during winter 2009 in the Gulf of Alaska and summer 2009 in the Bering Sea to evaluate whether seasonal and geographical differences existed in the juvenile fish aggregation patterns. Size- and shape-related aggregation descriptors (e.g., height, length, volume, and surface area) are described, and the variability in these metrics as a function of time and space is explored. Particular challenges for using the ME70 as a tool to describe the small-scale spatial patterns of marine animals are highlighted.
A low-frequency underwater sound source for seismic exploration.
Authors: Hixson Elmer L.
Published: October 2009

A very low-frequency (1–10 Hz) sound source is needed for greater penetration in the earth below a water layer. A neutral buoyant acoustic dipole is proposed for this purpose. With the dipole positioned vertically near the pressure release surface, the upward wave produced is inverted and adds to the downward wave. A model of such a dipole to operate in the range 20–40 Hz was built. It was driven by an inertial force generator. It was tested in an 11-m deep tank under low signal/noise conditions. Only near field pressure and water loading could be measured. In order to get design parameters for a 1–10 Hz dipole, scaled experiments using dipoles operating in the 3–5 kHz region with adjustable source spacing and depth were built and tested. A trade-off between source spacing for greater sound pressure and depth for summing the two waves were studied. In the deep tank, near- and far-field pressures were measured. [This study was supported by EXXONMOBIL.]
Shear waves and grain-rolling in granular media.
Authors: Chotiros Nicholas P. , Isakson Marcia J.
Published: October 2009

In a randomly packed unconsolidated granular medium, there is a random asymmetry in mechanical coupling between grains that has been shown to cause an increase in the effective inertia, hence a reduction in sound and shear wave speeds [N. P. Chotiros and M. J. Isakson, J. Acoust. Soc. Am., 121, EL70–EL76 (2007)]. The increase in inertia for shear waves is revisited because, in addition to the incoherent motion due to the random asymmetry, there is an additional component due to coherent grain rotation. Shear wave speed is predicted to be dependent on grain diameter, as well as the contact stiffness. [Work supported by ONR, Ocean Acoustics.]
Exploiting geophysical phenomena in processing seismic array data for border subsurface surveillance.
Authors: Holmes Jason D. , Aylward Erin, M. , Krumhansl Peter A. , McNeil Richard J. , Fabbri Darren R. , Fortin Christopher S. , McKenna Jason R. , Mattice Michael S. , McComas Sarah
Published: October 2009

The ability to detect tunneling activity under borders and perimeters has become an increasingly important problem. Persistent, automated, passive surveillance of expansive areas for tunnel activity is a technical challenge because of the processing and hardware costs. Further, data bandwidth concerns prohibit transmission of large amounts of time-series data to a central processing location but there remains a desire for human review of suspect signals and archiving to develop trends in time. To meet these technical challenges, sensor array and signal processing approaches which exploit geophysical phenomena to distinguish tunnel activity from surface noise were developed to rapidly and reliably detect potential subsurface threat signals with a minimized set of sensors, very low data bandwidth requirements, and a reduced set of centralized processing hardware. Time series review and archiving can then be performed for limited sets of the most suspect data. Analysis and results from recent controlled tunneling experiments on an operational system will be presented. [Work sponsored by U.S. Army Engineer Research and Development Center.]
Biologically inspired ultrasonic measurements of porous media, with applications in geophysics.
Authors: Hopper C. , Assous S. , Lovell M. A. , Gunn D. A. , Jackson P. D. , Rees J. G.
Published: October 2009

Biologically inspired ultrasound has been investigated for measuring properties of materials in an underwater environment. Broadband transducers have been deployed which operate in the 40–200-kHz frequency range, with similar frequencies to those used by some echolocating mammals. Signals have been designed, which optimize the available bandwidth of the transducer, and analysis procedures have been developed to extract the desired information from acquired data. Measurements on single-layer targets, comprising plastic, metal, and glass, in solid and porous forms have established the performance of the system on well-controlled synthetic samples. The target thicknesses ranged from 0.5 to 40 mm, thus spanning the wavelength range of the signals used. Adequate penetration of the ultrasound into the samples, at the frequencies used, was demonstrated. Material and thickness discrimination was possible using frequency domain results, and modeling of the traces was performed in order to extract velocity and attenuation information. Scanning electron microscopy measurements on the porous targets revealed structural information that informs the interpretation of the ultrasonic results. The work on synthetic targets forms a basis to inform experimentation on natural geological materials exhibiting a wide range of structural characteristics. Initial results for sandstone samples are presented.
Perception of timbre dimensions: Psychophysics and electrophysiology in humans.
Authors: Caclin Anne , Giard Marie-Hélène , McAdams Stephen
Published: October 2009

Timbre is a perceptual attribute that characterizes the identity of a sound source. Psychoacoustical experiments have revealed that this perceptual attribute is multidimensional, with timbre dimensions (such as sharpness or brightness) corresponding to a variety of acoustical parameters: attack time, spectral centroid, spectrum fine structure, spectral flux, etc. The question arises whether timbral dimensions are processed holistically or separately in the auditory system. This issue was addressed in a series of behavioral and event-related potential (ERP) studies in humans [Caclin et al., J. Acoust. Soc. Am. (2005); J. Cogn Neurosci. (2006); J. Cogn Neurosci. (2008); Brain Res. (2007)]. Different timbres were created by manipulating attack time, spectral centroid, and spectrum fine structure. Dissimilarity ratings confirmed that these three parameters were indeed major determinants of timbre. Their representation in auditory sensory memory was explored using the mismatch negativity (MMN) component of the auditory ERP. MMN results indicated mainly separate sensory memory representations of these dimensions in auditory cortex. Using Garner interference paradigm, evidence was found for an interactive processing of timbre dimensions at other levels of analysis than sensory memory, including early perceptual processing stages. These results can be synthesized in a model of timbre perception postulating separate channels of processing for different timbre dimensions, with cross-talk between those channels.
Development of auditory phase-locked activity for music sounds.
Authors: Shahin Antoine
Published: October 2009

The auditory cortex undergoes anatomical and functional development that reflects specialization for learned sounds. Auditory maturation is evident in the transient auditory evoked potentials (AEPs) and auditory phase-locked oscillatory activity. Development of AEPs and the phase-locking strength of oscillatory auditory responses to piano, violin, and pure tones were examined. The hypothesis was that if oscillatory activity in different frequency bands reflects different aspects of sound processing, then the development of phase-locking at these frequencies will have different maturational trajectories. Phase-locking for theta (4–8 Hz), alpha (8–14 Hz), lower-to-mid-beta (14–25 Hz), and upper beta and gamma (25–70 Hz) bands strengthened with age and was stronger for musical than pure tones. The phase-locking increase for gamma and upper beta bands mainly reflected the maturation of the spectral representations for sounds. In contrast, increase in phase-locking for theta, alpha, and lower-to-mid-beta was mainly attributed to sensitivity to sound temporal onset rise time. Frequency-specific phase-locking provides a tool to assess auditory development for spectral and temporal aspects of naturalistic complex sounds. [This research was supported by grants from the Canadian Institutes of Health Research and the National Institutes of Health, National Institute on Deafness and other Communication Disorders.]
The role of formant positions and micro-modulations in blending and partial masking of musical instruments.
Authors: Reuter Christoph
Published: October 2009

In experiments about the distinction of instruments playing in unison, it has been shown that timbres with overlapping formant areas are blending homogeneously whereas timbres with different formant areas are distinguishable very well (Reuter, 1996). On the other hand timbre separation is enhanced by micro-modulations and vibratos [e.g., McAdams (1982); Reuter (2007)]. The aim of this contribution is to find out to what extent timbre separation is influenced by different micro-modulations/vibratos versus different formant positions. 30 subjects listened to scale fragments of simultaneous playing instruments with equivalent formant areas and with different formant areas, with and without starting/ending transients, and with and without vibratos/micro-modulations. They had to answer the following question: Do you hear one sole instrument (or two of the same instruments) or do you hear two different instruments? In almost all cases featuring equivalent formant areas most of the subjects perceived one blending timbre, independent of the presence of vibratos/micro-modulations and transients. In the presence of vibratos/micro-modulations, differing formant areas predominantly led to the perception of two different timbres. Without vibratos/micro-modulations, timbre separation is much worse. These observations are explainable by a psycho-acoustical model of timbre perception.
Intravascular ultrasound and photoacoustic imaging.
Authors: Emelianov Stanislav
Published: October 2009

Catheter-based intravascular ultrasound (IVUS) is one of the imaging tools for the clinical evaluation of atherosclerosis. However, histopathological information obtained with IVUS imaging is limited. We developed a combined intravascular photoacoustic (IVPA) and IVUS imaging to characterize atherosclerotic plaques. The amplitude, spectral, and temporal characteristics of the photoacoustic signal are primarily determined by optical absorption properties of different types of tissues and can be used to differentiate the lipid, blood, fibrous, and fibro-cellular components of an inflammatory lesion. Furthermore, using bioconjugated contrast agents such as metal nanoconstructs, molecular IVPA imaging is possible since different molecules are overexpressed during various stages of atherosclerosis. Imaging experiments were performed using clinical IVUS imaging catheters interfaced with a pulsed laser system. The performance of the IVPA/IVUS imaging was assessed using vessel-mimicking phantoms. To detect the lipids in the plaque and to assess plaque composition, multi-wavelength (680–950 nm) spectroscopic IVPA imaging of a normal and an atherosclerotic rabbit aorta was performed. Molecular and cellular IVPA imaging was demonstrated using intravenously injected plasmonic nanoparticles. Finally, IVPA imaging was used to visualize coronary stents within the vessel wall. Our studies suggest that plaque detection, characterization, and even treatment can be improved using the combined IVPA.
Optical detection of motion generated in soft tissue by a focused ultrasound beam.
Authors: Bossy Emmanuel
Published: October 2009

This presentation will discuss various approaches combining light and sound for tissue characterization. All the approaches discussed here involve the optical detection of motion generated at depth in tissue by use of a focused ultrasound transducer. In the first part of the presentation, the acousto-optic imaging approach will be described, in which the optical phase modulation created by an ultrasound beam is used to derive optical properties with the resolution of the ultrasound beam. In particular, it will be demonstrated that randomly phase-modulated millisecond ultrasound burst can be used to obtain both transverse and axial resolutions. In this first approach, the optically detected motion consists of the ultrasonic motion of insonified light scatterers. In the second part of the presentation, it will be demonstrated that it is also possible to optically detect the transient shear motion generated by the acoustic radiation force in soft tissue. As for acousto-optic imaging, this approach is based on the interaction between a diffuse coherent light field and a localized motion and therefore provides localized information in the sample. In addition to provide information on optical properties, this approach also provides information on shear stiffness on the medium. For both approaches, experimental results obtained in vitro on tissue or tissue-mimicking phantoms will be shown, and the current challenges toward in vivo measurements will be discussed.
In vivo photoacoustic tomography and its clinical application.
Authors: Kim Chulhong , Wang Lihong, V
Published: October 2009

High-resolution volumetric optical imaging modalities, such as confocal microscopy, two-photon microscopy, and optical coherence tomography, have become increasingly important in biomedicine. However, due to strong light scattering, the penetration depths of these imaging modalities are limited to the optical transport mean free path (1 mm) in biological tissues. Photoacoustic imaging, an emerging hybrid modality that can provide strong endogenous and exogenous optical absorption contrasts with high ultrasonic spatial resolution, has overcome the fundamental depth limitation while maintaining high spatial resolution. The image resolution, as well as the maximum imaging depth, is scalable with ultrasonic frequency within the reach of diffuse photons. In biological tissues, the imaging depth can be up to a few centimeters deep. In this presentation, the following topics of photoacoustic imaging will be discussed; (1) multi-scale photoacoustic imaging systems, (2) non-invasive sentinel lymph node mapping using photoacoustic imaging and its clinical application, and (3) functional and molecular photoacoustic imaging.
Acousto-optic detection of high-intensity focused ultrasound lesions in real time.
Authors: Draudt Andrew B. , Lai Puxiang , Murray Todd W. , Cleveland Robin O. , Roy Ronald A.
Published: October 2009

Tissue ablation by high-intensity focused ultrasound (HIFU) leads to changes in the optical absorption and scattering of the tissue. Here acousto-optic (AO) sensing was used to detect HIFU induced changes in the optical contrast of chicken breast. The tissue was insonified by 1-MHz HIFU and illuminated by infrared light. The diffuse light that exited the tissue was collected and processed using photo-refractive crystal based interferometer configured to detect phase modulated light that had interacted with the HIFU. Here the HIFU served both to ablate the tissue and elicit the AO response, and as a lesion forms, the increase in optical absorption and scattering should result in a reduction in modulated light being detected by the interferometer. The HIFU was amplitude modulated with a 50% duty cycle at 50 Hz and the interferometer output was processed through a lock-in amplifier tuned to the modulation frequency to improve the signal-to-noise ratio. Using a focal pressure of 6 MPa (derated from water), the AO signal remained constant for ∼10 s of HIFU, and a “post-mortem” in this time-frame found no detectable lesion. Once the AO signal decreased a lesion was always detected and the lesion size correlated with the amount of decay of the AO signal. [Work supported by NSF CenSSIS EEC-9986821]
Plasma conditions during single bubble sonoluminescence.
Authors: Suslick Kenneth S. , Flannigan David J.
Published: October 2009

There is a remarkable lack of experimental data on the conditions created during cavitation bubble collapse. Indeed, only recently has strong evidence of plasma formation been obtained during single bubble cavitation. Here we have determined for the first time the plasma electron density and the ion broadening parameter during single-bubble sonoluminescence and examined them as a function of acoustic driving pressure. We find that the electron density spans four orders of magnitude and can exceed 10×1021/cc (which is comparable to the densities produced by intense laser-induced inertial confinement fusion experiments, e.g., the NOVA ICF laser at Livermore) with effective plasma temperatures ranging from 7000 to more than 16 000 K. At the highest acoustic driving force, neutral Ar lines can no longer be used as spectroscopic reporters due to the extent of ionization and to leveling of the population of states. Accounting for the temporal profile of the sonoluminescence pulse suggests that the ultimate conditions generated inside the collapsing bubble may far exceed those determined from emission from the outer transparent region of the plasma core.
Infrared position tracking.
Authors: Sunny Megha
Published: October 2009

In this work we examine methods for position determination using infrared-sensors. We are using a Wii remote and infrared LED glasses to find the distance between the head and the Wii remote sensors. The relative distance is calculated by using triangulation method. The spatial orientation of the head with respect to the Wii remote sensor was also measured using the infrared LED and the infrared sensors of Wii remote. The spatial data obtained will control the acoustic characteristics of a head related transfer function that will be used in source localization in virtual environments.
A method for analyzing the biodiversity in bat pinnae.
Authors: Müller Rolf , Ma Jianguo
Published: October 2009

The pinnae of bats show conspicuous interspecific variability in global as well as in local shape features. Evidence from case studies suggests that at least some of these features may serve acoustic functions. Consequently, the variability in pinna shapes may represent evolutionary adaptation patterns to a range of different acoustic sensing tasks. An automated non-parametric method has been developed to extract these patterns from the biodiversity in pinna shapes. It allows the computation of three-dimensional principal components, eigenears, from high-resolution digital representations of the entire pinna surface. To achieve this, the inner and outer pinna surfaces that diffract incoming sound and thereby define the pinna’s acoustic properties have been subjected to a cylindrical transformation. The radius values of discrete points on the pinna’s surfaces have been taken to define members of a continuous valued vector space suitable for a principal component analysis. The results of the analysis show that the biodiversity in pinna shapes can be approximated well by a reduced number of dimensions that could be used to capture design trends. The natural global-to-local ordering of the eigenears can be used as a recipe to describe the sequential “design” of individual bat ears from a basic shape.