bluuebunny/crossref_metadata_2025 huggingface dataset:
Learning environmentally dependent feature representations for classification of objects on or buried in the seafloor
Authors: Summers Jason E. , Havens Timothy C. , Meyer Thomas K.
Published: May 2014

Classification performance of underwater objects is determined in large part by the acoustic response of the environment. This is a consequence of environmental clutter and of the altered response of objects that occurs through interaction with the environment—particularly for low-frequency scattering from objects on or buried in the seafloor. Therefore, to achieve robust classification, it is necessary that signal-processing algorithms account for the local context of the underwater environment. Theoretical, experimental, and numerical studies have characterized well the influence of the environment on scattering from objects for a variety of burial conditions, object shapes, structures, and materials, and sediment types and topographies. However, the relationship between these results and measurable features useful for classification remains to be fully developed. Here, we describe a machine-learning approach to selecting features for environmentally adaptive classification that seeks to algorithmically select from measured and modeled data those feature representations best suited to object classification in varying environmental contexts. We follow a data-driven online learning approach that, while leveraging current theories and models describing environment/target interaction, does not impose an artificial limitation on the true diversity of targets and their environments. Preliminary results are presented for measured and modeled data.
Selected prosody features in an accent learning system
Authors: Perdereau Xiao
Published: May 2014

Human speech interaction experiments have been structured as temporal and spectral representations of acoustical waveforms to better understand human facilities in handling previously unheard non-native accents of a natural language. We used Mandarin as target language for native and non-native speakers. Identical linguistic materials have been applied to both human and machine learning process. The word sequences have been selected for inference. The outcomes from human speech interactions are analyzed using computer. Speech prosody characteristics have been selected to identify and to classify naturally accented speeches. Correct and incorrect word sequences for each accented speech are discriminated. Starting with a limited stored samples of natural speech data, new signals of accented speech could be detected. Relevant acoustic features extracted from human speech are used in a comparative processing algorithm. Modified speech prosodies are produced artificially by modulating a relatively small number of physical parameters. On one hand, the variabilities regenerated by the dynamic device are fed foreword for extended human accented speech training, on the other hand, recycled acoustic signal acquisitions improve our machine knowledge source through gradual accumulation. This work is part of the development of multimedia tools integrated in an accent learning systems.
Buzz, squeak, and rattle noise classification by using acoustic-fingerprinting technology
Authors: Seo Dae-Hoon , Choi Jung-Woo , Kim Yang-Hann
Published: May 2014

The buzz, squeak, and rattle (BSR) noises are three representative types of the automotive interior or exterior noise. Some of BSR noises have very short duration in time, and hence, it is difficult to detect various BSR noises in low SNR situation. However, each BSR noise signal has a unique time-frequency characteristic, depending on the various contacting materials as well as the excitation forces. Therefore, it is necessary to utilize the time-frequency characteristic of the BSR noise to specify the origin of a noise source. In this paper, we propose a novel method and system for identifying BSR noises. For accurate classification of noise sources, a noise-fingerprinting and matching technique based on the pattern classification is devised. The identification test with the real BSR noise data shows that the proposed method can accurately classify the noise source even in the low SNR condition.
Spectrotemporal Gabor filters for feature detection
Authors: Smith Leslie S. , Abel Andrew K.
Published: May 2014

Features (landmarks) in sound are located in time and spectrum. Two dimensional (time x spectrum) Gabor filters can be used to detect useful classes of these. We use a set of logarithmically spaced bandpass filters whose outputs are coded as spikes to perform spectral analysis. These are convolved with Gabor filters to create spectrotemporal feature maps. Using auditory-nerve like spikes to code zero-crossings retains precise timings and amplitude information, and makes convolution computation relatively straightforward. Gabor patches with “horizontal” bars (parallel to time axis) can be used to detect harmonicity, and patches with “vertical” bars (parallel to spectrum axis) can detect envelope modulations. Because the time resolution is maintained in the preprocessing, vertical bars may be close together (e.g., 5 to 10 ms apart), enabling detection of amplitude modulation due to unresolved harmonics. This is useful for both for speech voicing detection, and for animal utterances. Such filters may be localized in spectrum, allowing tracking of voicing energy. Filters with bars at other angles can detect frequency modulation. Using constellations of these features (and others, such as onsets), we can characterize and interpret sound sources.
Modeling range dependent sediment and interface roughness effects on propagation loss with finite elements
Authors: Isakson Marcia , Chotiros Nicholas
Published: May 2014

At the Target and Reverberation Experiment (TREX) off the coast of the Florida panhandle in May 2013, propagation loss was measured over a track with significant sediment and interface roughness variability. In this study, the finite element method is applied to model the effects of sediment and interface roughness variability on transmission loss. Finite elements provide a full wave solution to the Helmholtz equation to the accuracy of the discretization. Therefore, it provides both forward and backward propagation fields. Where available, data will be taken from TREX environment measurements. Additionally, the results will be compared with an energy loss model which relies on the product of the range dependent reflection coefficient. [Work supported by ONR, Ocean Acoustics.]
Mode analysis of distant shipping noise in the SPICE experiment
Authors: Farrokhrooz Mehdi , Wage Kathleen E. , Dzieciuch Matthew A. , Worcester Peter F.
Published: May 2014

A major source of ambient noise for frequencies below 100 Hz is due to distant shipping (Wenz, 1962). Shipping noise is trapped in the SOFAR channel and propagates long distances. Since this part of ambient noise excites the low normal modes, it decays with increasing depth. A modal analysis of shipping noise provides valuable insights about its depth dependence. SPICEX offered a unique opportunity to study the ambient noise in the Northeastern Pacific using two vertical line arrays an axial array and a deep array. A 40-hydrophone axial array spanned the SOFAR channel and recorded ambient noise at regular intervals over a year. The axial array data makes it possible to estimate the wavenumber-frequency spectra of ambient noise. We can estimate the mode powers associated with the angle-limited noise in the wavenumber-frequency spectra using a least squares fit. Given the estimated mode powers, depth-dependence of the shipping noise component is predictable. This talk compares the predicted noise levels as a function of depth with data measured by the deep SPICEX line array.
Correlation matrices as a method of source function isolation and classification in ambient noise
Authors: Nichols Stephen , Bradley David L.
Published: May 2014

At low frequencies (1–100 Hz), the deep-ocean ambient noise field is a mixture of many source types, including seismic activity, marine life, ship traffic, seismic airgun surveys, and nonlinear surface wave interactions. The location of the sensors used to monitor these types of noise typically result in an extremely dynamic recorded ambient noise field. This study proposes the use of correlation matrices as a tool for identifying the predominant noise sources present in samples of ambient noise. These correlation matrices work by identifying frequency ranges in which the noise levels tend to change at the same time, thus identifying frequency ranges where noise is driven by one particular source mechanism. The effectiveness of this strategy will be demonstrated using low-frequency deep-ocean ambient noise recorded in the Pacific, Atlantic, and Indian Oceans by the Comprehensive Nuclear-Test Ban Treaty Organization (CTBTO) hydroacoustic monitoring system.
Estimation of seabed bottom loss using wideband signal for underwater acoustic communication
Authors: Byun Sung-Hoon , Kim Sea-Moon , Lim Yong-Kon
Published: May 2014

Performance of acoustic communication through shallow underwater channel is affected by surface and bottom interaction, and the bottom loss has great importance for long-range signal transmission. In 2013, KRISO has performed a shallow-water communication experiment near Jeju island, South Korea, and the experiment aims at evaluating communication link budget as well as measuring the channel fading statistics. The measured sound velocity profiles show the existence of strong thermocline resulting in downward refraction and therefore its long-range signal propagation is strongly dependent on the seabed characteristics. We use a wideband signal, which was originally designed for channel impulse response estimation. The signals were recorded using a four-element receiver array with two different source depth configurations which enable observing the seabed at various grazing angles. The estimated bottom loss is used to estimate the transmission losses at longer ranges, and they are compared with the measured values to examine the estimated bottom loss.
Simulation and analysis of acoustic impedance measurement techniques for marine sediments using sonar
Authors: Ristow João P. , Barrault Guillaume , Cordioli Julio A. , Azevedo Gregório G. , Klein Antônio H. , Bousfield Marina
Published: May 2014

The characterization of seabed sediments using acoustics techniques is a wide field of research. A key feature in the sediment characterization is the estimation of its acoustic impedance, from which density and wave propagation speed in the sediment can be derived. The sea bottom acoustic impedance is a property that rules the backscattering strength, together with other sediment features such as slope and roughness. In this sense, sonar devices can be used to measure the backscattering strength of a material lay up on the sea bottom and estimate the aforementioned sediment features. However, one of the main difficulties is to obtain sufficient complementary information in order to decompose the backscattering strength of a giving sea bottom and obtain its proper acoustic impedance. Hence, the aim of this work is to evaluate and compare different techniques for measurement and signal processing that will be used to indirectly calculate the sediment's acoustic impedance from numerically simulated sonar data.
Propagation of nonlinear sound beams in marine sediments
Authors: Lee Hunki , Noh Eunghwy , Kwon Oh-Cho , Ohm Won-Suk
Published: May 2014

Parametric arrays are recently considered as directional sound sources for locating buried objects in marine sediments. To understand how nonlinear sound beams generated by parametric arrays propagate in marine sediments, a theoretical framework that accounts for the combined effects of diffraction, absorption, nonlinearity, and the physics of sediment is necessary. In this paper, the KZK equation is extended to augment a number of well-known sediment models. Nonlinear evolution of sound beams are computed and compared under different sediment models, namely, the fluid model, Buckingham's grain-shearing model, the Biot-Stoll model, and the effective density fluid model (EDFM). [This work was conducted in the Unmanned Technology Research Center (UTRC) sponsored by the Defense Acquisition Program Administration (DAPA) and the Agency for Defense Development (ADD) in the Republic of Korea.]
Parameter measurement research of sonar echo highlights
Authors: He Cheng , Zhao Anbang , Zhou Bin , Song Xuejing , Niu Fang
Published: May 2014

Highlights sonar model provides an important basis for complex target modeling. In this paper, a parameters measurement method for the far-field sonar target highlight is proposed, time reversal mirror (TRM) technology and transponder technology combined with this method. First, get the number of target highlights. Then, put transponders with the same number along underwater the target which is measured, those transponders must be close at each highlight. A wideband signal is transmitted at measuring position which is far away from target, those transponders at target side answer one by one. Record the echoes coming from target and transponders. Time-delay, amplitude, and phase-jump of highlights can be calculated by processing those echoes in TRM and matrix operations methods. It is found through simulation by MATLAB that this target highlight algorithm can accurately measure the three important parameters of highlight model in negative SNR. By getting those parameters accurately, some other parameters can be calculated, for example, target strength. Target echo can also be predicted with those parameters, it will be very useful in target strength measurement and active target stealth technology then.
Active acoustic detection of subsea oil and gas leaks; model prediction and measurements
Authors: Pedersen Geir , Hauge Rune , Kubilius Rokas
Published: May 2014

There is a need in the oil and gas industry for technology for real time monitoring of subsea structures. National research strategies emphasize the need to develop innovative solutions to detect, contain, and clean up spills. The technology should ideally cover a large area and be able to detect leaks up to 500 m from the sensor. As part of a project where a leak detection technology based on active acoustics is developed, effective medium models have been used to predict the acoustic signal from small oil and gas leaks. Model results were compared with multifrequency data from controlled in situ measurements of oil and gas releases, collected with scientific echosounders. The measurements also include stereo camera images for bubble/droplet and plume size estimation. The models generally predict the measurements within 3 dB, when taking into account the variability in plume dimensions and bubble sizes the difference is smaller.
Acoustic propagation in surface channel formed by low salinity water in the East China Sea and the tropical Atlantic Ocean
Authors: Kim Juho , Kim Hansoo , Paeng Dong-guk , Lee Jongkil
Published: May 2014

Salinity is usually neglected in underwater acoustics because of its minimal contribution on sound speed variation. However, it is required to consider in calculation of sound speed and acoustic propagation for low salinity water freshened by continental run-off. Furthermore, the acoustic characteristics of low salinity environment are not fully investigated yet. Therefore, regional difference of acoustic propagation in low salinity water was studied by comparing the acoustic characteristics of the East China Sea with those of the tropical Atlantic Ocean in this paper. Frequency dependency of sound propagation in the haline channel was analyzed with transmission losses and low frequency cut-off using oceanic data from NODC (National Oceanographic Data Center). The tropical Atlantic Ocean showed larger channel depth, critical angles and less transmission loss in the haline channel than the East China Sea. The cut-off frequency in the haline channel was computed as around 1 kHz and 5 kHz in the tropical Atlantic Ocean and the East China Sea, respectively. The effects of low salinity water on sound propagation showed regional characteristics, and need to be considered in sonar operation near sea surface. [This work was supported by Defense Acquisition Program Administration and Agency for Defense Development under the contract UD130007DD.]
Coherence measurements of acoustic normal modes during one month of internal wave events on the New Jersey continental shelf
Authors: Wan Lin , Mohsen Badiey
Published: May 2014

During the Shallow Water Acoustic Experiment 2006 (SW06) conducted on the New Jersey continental shelf, the three-dimensional (3D) temperature field for one month of internal wave (IW) events has been reconstructed by Badiey et al. [J. Acoust. Soc. Am. El. 134(5), 4035 (2013)]. The aforementioned IW events, with the angle between the acoustic track and the IW front varying from -8° to 83°, were measured while simultaneously acoustic signals were transmitted from fixed sources at an along-shelf distance of about 20 km with frequencies at 87.5–112.5 Hz (m-sequence), 175–225 Hz (m-sequence), 270–330 Hz (chirp), and 470–530 Hz (chirp), respectively. The acoustic signals were recorded by an L-shaped hydrophone array moored inside the area with IW measurements. The main goal of this paper is to analyze the coherence of acoustic normal modes accompany with the simultaneously measured IW events. The coherence of acoustic normal modes decomposed from the measured acoustic field is obtained as a function of frequency and IW parameters, such as the IW propagation direction, amplitude, coherence length, etc. The relationship between the modal coherence and IW parameters is discussed. [Work supported by ONR322OA.]
Low frequency sound absorption in the Arctic Ocean: Potential impact of ocean acidification
Authors: Browning David , Herstein Peter D. , Scheifele Peter M. , Hasse Raymond W.
Published: May 2014

The principal mechanism for low frequency absorption in seawater is a boron reaction that is pH dependent; the lower the pH, the lower the absorption. Twenty seven years ago, Mellen et al. [J. Acoust. Soc. Am. 82, S30 (1987)] computed the low frequency sound absorption for the Arctic Ocean. Since the time the carbon dioxide (CO2) level in the atmosphere has been continually increasing. Experts predict that the resulting ocean acidification may increase by up to 170% this century. Acoustically, the Arctic Ocean is most sensitive to rapid change not only because the cold water readily absorbs CO2, but also because the sound channel axis is at or near the surface. The range of reduction in the low frequency sound absorption is presented based on possible future acidification scenarios, mindful that this is just one component of a complex evolution that is occurring in the Arctic.
Hydroacoustic signals of Antarctic origin detected at ocean-bottom seismic stations off New Zealand
Authors: Ball Justin S. , Sheehan Anne F.
Published: May 2014

Glacial calving from polar ice sheets is an important indicator of global climate change, and knowledge of ice discharge rates is useful for predicting global sea level variability and deep ocean circulation patterns. Since calving events are difficult to observe in-situ due to the remoteness of polar regions, the remote detection of hydroacoustic signals originating from these events is a useful monitoring tool for climatologists. We have observed hydroacoustic T-phases on an Ocean Bottom Seismic (OBS) network of 30 seismometers and differential pressure gauges that was deployed off the South Island of New Zealand in 2009–2010. These signals are emergent and strongly dispersive, containing most of their energy in the band between 5 and 15 Hz. We estimated backazimuths for events recorded on differential pressure gauges using array beamforming and F-K analysis. Our results suggest that some observed events originate in the vicinity of Ninnis and Mertz glaciers on George V Coast, East Antarctica, in general agreement with epicenters located by prior surface-wave based calving detection studies.
Effects of ambient pressure variation on the subharmonic response from contrast microbubbles
Authors: Mobadersany NIma , Katiyar Amit , Sarkar Kausik
Published: May 2014

Ambient pressure dependent subharmonic response scattered from encapsulated contrast agent is investigated for non-invasive estimation of local blood pressure. Bubble dynamics is simulated using two different models of the encapsulation: the strain-softening elastic model and the Marmottant model. Unlike fundamental response, subharmonic response from a bubble occurs in a narrow range of excitation pressures—it appears only above a threshold excitation and disappears at higher excitation. The variation in subharmonic responses is chaotic with increasing ambient pressure at very low excitation frequencies. On the other hand, for high excitation frequencies, the subharmonic response increases with increasing ambient pressure For intermediate frequencies, the variation can be either monotonic increase, monotonic decrease, or nonmonotonic with increasing ambient pressure depending upon the excitation intensity. The simulated results will be discussed taking into account the effects of ambient pressure variation on the subharmonic threshold. [Partially supported by National Science Foundation.]
StemBells: Localized stem cell delivery using targeted microbubbles and acoustic radiation force
Authors: Kokhuis Tom , Skachkov Ilya , Naaijkens Benno , Juffermans Lynda , Kamp Otto , van der Steen Antonius , Versluis Michel , de Jong Nico
Published: May 2014

The use of stem cells for regenerative tissue repair is hampered by the low number of cells delivered to the site of injury. To increase the delivery, we developed a new technique in which stem cells are coated with functionalized microbubbles, creating echogenic complexes dubbed StemBells. StemBells are highly susceptible to acoustic radiation force; this acoustic force can then be used after injection to deliver the StemBells locally at the treatment site. The dynamics of StemBells during ultrasound insonification was characterized using high-speed optical imaging and is described in an accompanying paper. Here, we investigate the feasibility of manipulating StemBells acoustically after injection employing a chicken embryo model, allowing for the real-time optical observation of the effects of acoustic radiation force in vivo. StemBells were infused by placing a custom-made catheter into one of the vitelline veins. Acoustic radiation force (1 MHz, P = 200–450 kPa, 10% duty cycle) was observed to propel StemBells from the centerline of the microvessels (200–500 μm) to the wall distal from the transducer. Peak translational velocities increased with pressure and varied between 50 μm/s to 300 μm/s. The acoustic radiation force had no effect on the trajectory of bare stem cells.
Racquetball exposed: Analysis of decay times and exposure levels in racquetball courts
Authors: Shaw Matthew D. , Mitchell Eric C.
Published: May 2014

Racquetball courts are interesting acoustic spaces. The architecture varies from court to court; therefore, the acoustic environment also changes. This talk will present reverberation time measurements of two types of courts: fully enclosed courts and courts with open viewing areas. Similarities and differences in the decay times will be discussed. This research will also investigate a player's exposure level during a typical racquetball match.
Using relative Doppler from multiple observations of dolphin whistles as an aid to localization and tracking
Authors: Hursky Paul
Published: May 2014

A variety of techniques have been used to track marine mammals from their vocalizations. For example, hyperbolic fixing and cross-fixed beams are well-developed approaches, both requiring multiple separated sensors. Dolphin vocalizations, consisting of clicks and whistles, pose some interesting challenges as well as opportunities. Dolphins are often observed in groups and their vocalizations can be quite dense in time. Before their sounds can be used on separated sensors, they must be associated, so that different sounds, for example, are not mistakenly assumed to be the same sound. Since it is often difficult to distinguish different clicks, it becomes difficult to associate (and thus track) them, when there are a lot of them (either from the same animal, or from many animals). By contrast, whistles typically are much easier to associate, even if overlapping. Whistles last seconds at a time and have distinctive melodies that span tens of kilohertz in bandwidth, often with harmonics. The high frequency of dolphin whistles and the fact that these animals are in constant motion suggests a novel feature to incorporate into their tracking—we discuss using relative Doppler, estimated from observations of whistles on multiple separated sensors, as an aid to localization and tracking.
Estimating the range of Baleen whale calls recorded by hydrophone streamers during seismic surveys
Authors: Abadi Shima H. , Crone Timothy J. , Tolstoy Maya , S. D. Wilcock William , Carbotte Suzanne M.
Published: May 2014

Like all sources of anthropogenic sound in the oceans, seismic surveys have the potential to disturb marine mammals and impede their communications. Since airgun arrays produce a considerable amount of low frequency energy, their impact on Baleen whales may be most significant. For these reasons, extensive mitigation efforts accompany seismic surveys, including visual and acoustic monitoring, but additional approaches could be useful to verify these efforts and study the behavior of whales. One approach is to utilize the hydrophone streamer to detect and locate calling Baleen whales. To develop this method, data are being analyzed from a seismic reflection survey conducted with the R/V Langseth off the coast of Washington in summer 2012. The seismic streamer is 8 km long with 636 hydrophones sampled nearly continuously at 500 Hz. The work focuses on time intervals when only a mitigation gun is firing because of marine animal sightings or turns at the ends of lines. Ranges and orientations are estimated by calculating the signal arrival angles for different groups of receivers. Data from the marine mammal observers on the R/V Langseth and other ships in the area are used to verify the analysis. [Sponsored by NSF.]
Measuring the sonic, infrasonic and seismic soundscape of the Southern White Rhinoceros (Ceratotherium simum simum) at a wildlife park conservation center
Authors: Wiseman Suzi , Wilson Preston S. , Sepulveda Frank
Published: May 2014

Many creatures, including the myopic rhinoceros, depend upon hearing and smell to determine their environment. Nature is dominated by biophonic and geophonic sounds quickly absorbed by soil and vegetation, while anthrophonic urban soundscapes exhibit vastly different physical and semantic characteristics, reflecting off hard geometric surfaces, distorting and reverberating, and becoming noise. Noise damages human physiologically, including reproductively, and likely damages other mammals. Rhinos vocalize sonically and infrasonically but audiograms are unavailable. They generally breed poorly in urban zoos, where infrasonic noise tends to be chronic. Biological and social factors have been studied but little attention if any has been paid to soundscape. To comprehensively describe the rhinos’ sonic, infrasonic and seismic environment at Fossil Rim Wildlife Center, one of the few U.S. facilities to successfully breed white rhinos in recent years, I began by comparing the sound metrics at different times of day in categories, for example, during visitation hours versus park closure. Further analysis will seek particular parameters known to be injurious to humans, plus those already known to impact animals. Later, the soundscapes of other facilities could be compared to seek correlations between their soundscapes and the health and well-being of the rhinos within their care.
Ultrasonic neuromodulation: Three conjectures common to the peripheral and the central nervous systems
Authors: Muratore Robert
Published: May 2014

The nervous system responds with finesse to incident ultrasound. Three conjectures are proposed, abstracted from the literature, which illustrate commonalities in the response of the peripheral and the central nervous systems, and serve as an introduction to the nascent field of ultrasonic neuromodulation. (1) A mathematical function fit to neuronal effect vs. acoustic dose has a root at a non-trivial dose. Above a threshold dose, nerves and brain regions are stimulated; at very high doses, normal neuronal activity is inhibited. Thus, there exists an intermediate dose balancing stimulus and inhibition. (2) An acoustic beam can modulate a neuronal region larger than that which it insonifies. Nerves can be stimulated by insonifying a small portion of their axon. Brain regions exhibit responses, such as spreading depression, to localized insonification. (3) The spatial precision of ultrasonic neuromodulation can be considerably finer than the incident acoustic beam width. Thicker nerve fibers are more resistant to the effects of incident ultrasound than are thinner fibers in the same nerve. Across the cortex, displacements of acoustic beams smaller than the beam width can achieve fine motor control. Each of these conjectures plays a role in current neuromodulation experiments.
Capacitive micromachined ultrasonic transducers with integrated electronics for neuromodulation applications
Authors: Khuri-Yakub Butrus T.
Published: May 2014

Capacitive Micromachined Ultrasonic Transducers (CMUT) are being made in practically any size (microns to mms), shape (flat or curved), and type (single element, 1-D array, 2-D array, rings, and annular arrays), and at frequencies from 10s of kHz to almost 100 MHz. Along with the transducers themselves, front-end electronics are being integrated as well to provide better performance and enable the use of arrays with a very large number of elements. One important aspect of these integrated arrays is that they can be used for imaging (anatomic and photo-acoustic functional), therapy (high intensity focused ultrasound), and more recently neuro-modulation. This talk will review CMUTs and the methods of integration, then show examples of ultrasound stimulation of lipid bilayers and Salamander retina. We show that the retina responds to ultrasound stimulation as well as it responds to light stimulation and that when the retina’s optical response is suppressed chemically it still responds to ultrasonic stimulus. We postulate the possibility of using CMUT 2D arrays as contact lens prosthetic devices capable of restoring some vision in some type of blindness.
Low intensity (55 kPa) 20 kHz ultrasound heals venous ulcers
Authors: Samuels Joshua , Weingarten Michael S. , Zubkov Leonid , Bawiec Christopher , Sunny Youhan , McDaniel Jane , Jenkins Lori , Margolis David , Lewin Peter
Published: May 2014

We report the results of a second clinical pilot study (n = 19) involving treatment of chronic wounds (venous ulcers) using novel, fully wearable ultrasound array applicator operating at 20 kHz and generating pressure amplitudes close to 55 kPa (about 100 mW/cm2, Sptp). The applicator was designed as compact, tether-free, device that can be comfortably worn by subjects at home, permitting active (combined with traditional compression) therapy away from the clinical setting. Patients with venous ulcers documented for over 8 weeks were enrolled from the Drexel Wound Healing Center and, following consent, were randomly assigned into treatment or control groups. Patients were treated weekly (15 min) for a maximum of 12 visits or until wound closure. Treatments were in addition to standard of care compression therapy as ordered by the physician. Of the patients receiving at least three treatments (n = 16), the ultrasound treated group had statistically improved (p < 0.04) rate of wound closure (reduction of 8.2%/wk) compared to the rate of wound closure for the control group (increase of 7.5%/wk on average). This study represents further proof of the potential healing power of low intensity, low frequency ultrasound. Optical measurements and in-vitro work continue to support these findings as well.
Modal transducers and Stan Ehrlich
Authors: Butler John L.
Published: May 2014

There have been a number of transducer designs which use the dipole mode of a piezoelectric cylinder to obtain directionality since Stan Ehrlich’s early patent (with P.D. Frelich), [“Sonar Transducer,” U.S. Patent 3,290,646, December 6, 1966] was first published. There is now a whole class of transducers, called vector sensors or hydrophones, which use the dipole mode in one or more directions. In addition to this, other designs have emerged which use modes higher than the monopole and dipole modes. For example, the added use of the quadrupole mode has allowed beam patterns from cylinders which approximate patterns from piston transducers. Work on the dipole mode and higher modes of spherical transducers and arrays allow 3-D acoustical coverage from one transducer or array. This presenters interest in modal excitation from transducers and arrays began after reading Stan’s patent, and interest developed further after working with Stan at Raytheon. A review of some of the transducers and arrays which we worked on will be presented, along with more recent work based on these modal concepts.
Nearfield of an electroacoustic transducer, with implications for performance measurement
Authors: Foote Kenneth G.
Published: May 2014

The spatial structure of the nearfield of an electroacoustic transducer is known to be complicated. This is illustrated by numerical modeling of the nearfield of an ideal planar circular piston in a rigid, infinite baffle. There are implications for performance measurements of electroacoustic transducers including hydrophones in tanks.
Analysis of nonuniform circular flexural piezoelectric plate transducers
Authors: Aronov Boris , Brown David A.
Published: May 2014

An analytical treatment of the circular flexural plate transducer having a nonuniform electromechanically active-passive (bilaminar) mechanical system is presented. The analysis is made using the energy method that was previously applied to calculating the parameters of uniform fully active (bimorph) circular plate transducers [Aronov, J. Acoust. Soc. Am. 118(2), 627–637 (2005)]. It is shown to first order approximation, that the vibration mode shapes do not change significantly for a large range of relative dimensions of the active and passive laminates of the mechanical system considered in terms of optimizing the effective coupling coefficient of the transducer. Therefore, the transducer can be considered as having a single degree of freedom, and its operational characteristics can be calculated using the same technique as previously used for uniform plates. The dependence of the resonance frequencies, effective coupling coefficients, and parameters of the equivalent electromechanical circuit on the relative dimensions of the active and passive laminates for several combinations of the active and passive materials are presented. The main results are in a good agreement with experimental data.
Communicating with the media: From the laboratory to the real world
Authors: Deutsch Diana
Published: May 2014

Scientists often view communicating with the media as a risky process, based largely on concerns that they might be held responsible for inaccuracies in reporting their work. Yet my experiences with the media have generally been very rewarding. Most frequently, those who have interviewed me have been well prepared and have thought broadly about the subject matter of my research. Our conversations have often induced me to think outside the box and have led to novel ideas for studies that might otherwise have been left undone. The potential for feedback has recently been enhanced by the development of social networks—these often pick up on reports in newspapers and magazines, and provide an important additional forum for discussion. In this talk, I describe some experiences that illustrate these points and offer some suggestions for interacting with the media so as to communicate research findings and their implications most effectively.
Interviews with the interviewers and interviewees
Authors: Piacsek Andrew A.
Published: May 2014

The basic conflict between scientist and journalist is that each wants to tell a story—but not necessarily the same story. Can they agree on a version that grabs and holds the attention of most people but is still true to the science? Despite the risks of being portrayed inaccurately, should researchers make an effort to talk to the press? This talk will address these questions by synthesizing a series of interviews conducted with two acoustics professionals who have had significant media exposure, a print journalist, a radio journalist, and an academic specializing in science journalism.
Regulatory inertia and community noise
Authors: Blomberg Leslie D.
Published: May 2014

Thirty and forty year old regulations are determining much of the acoustic environment. This paper examines regulations that have not kept up with the times or technology. Aviation, motorcycle, and truck regulations are examined in their historical context, as well as OSHA’s backup beeper regulations. Also, in many communities, local noise regulations are decades behind today’s best practices. The options and prospects for updating these regulations are discussed.
Spatial regression relations between urban forms and road-traffic noise
Authors: Chang Seo I. , Chun Bum Seok
Published: May 2014

Recent development of noise mapping tools allows us to generate sophisticated environmental noise maps where complicated acoustic phenomena including reflection by building facades, diffraction by horizontal and vertical edges of a building, and absorption by pavements can be considered with high level of accuracy. Therefore, if we have a noise map of an existing city and plan to do minor modifications, such as adding lanes to a road or locating new residential buildings along highways, we can assess and mitigate the induced impacts by simulating upon the existing noise map, e.g., installation of noise barriers or control of traffic flows. But, if a totally new city is built separately, what and how can we plan about the environmental noise? How can we do city-planning based on minimum information? What minimum information should be provided? Identification of the relations between urban forms and environmental noise can be helpful to city-planners at very early stage of planning. We performed spatial statistical analysis of road-traffic noise and urban forms by utilizing a GIS tool. Urban forms in the spatial regression model include residential and employee populations, building forms, traffic properties, and land-use pattern.
Differences between sound pressure levels measured outdoors in three heights commonly used in environmental noise impact assessment
Authors: de Souza Olmiro C. , Paul Stephan , Garlet Diego
Published: May 2014

In environmental acoustics, outdoor sound pressure level can be measured at different heights over ground. ISO 1996 recommends measurements at 4 m, which is representative for multi-storey residential areas and in accordance with EU directives for noise map modeling. For other areas ISO 1996 recommends measurements 1.5 m over ground, a height that corresponds to the median height of adults ears. In Brazil, 1.2 m are commonly used for outdoor measurements and noise map calibrations as this height is recommended by the Brazilian standard NBR 10.151-2000. The goal of this work is to investigate the relationship between SPL measurements obtained at these three heights. Measurements were taken close to roads at a university campus, roads that in some cases have high traffic flows. The differences between measured A-weighted equivalent SPLs (LAeq) at the different heights were statistically analyzed. Difference distributions were found to be closely to normal distribution with some outliers. Mean values of the SPL differences remained below 3 dB. From the data obtained, it seems acceptable to calibrate a noise map model at a different height from the measured one using the mean difference as a correction term.
The role of bubbles in the atomization of liquids and tissues
Authors: Simon Julianna C. , Sapozhnikov Oleg A. , Khokhlova Vera A. , Wang Yak-Nam , Kreider Wayne , Crum Lawrence A. , Bailey Michael R.
Published: May 2014

Ultrasonic atomization, or the emission of droplets from a liquid exposed to air, has been studied for many decades. The most accepted theory of atomization, the cavitation-wave hypothesis, states that droplets are emitted by a combination of capillary wave instabilities and cavitation bubble collapses. Recently, it was shown that tissues could also be atomized and that the result of atomization was surface erosion. Using a high static pressure chamber, we investigated the role of bubbles in the atomization of tissues and liquids. A 2-MHz, aluminum-lensed transducer was focused at the surface of either water or ex vivo bovine liver. In water at 1200 W/cm2 (p +  = 6.8 MPa, p- = 5.3 MPa), we found that atomization ceased at an overpressure of 6.9 MPa, yet droplets were again released when the static pressure was increased to 13.8 MPa. In tissue at a linear in situ intensity of 22 000 W/cm2 (p +  = 67 MPa, p- = 16 MPa), we found that a small increase in the static pressure (1.4 MPa) produced a qualitative change in atomization and caused thermal denaturation of the fractionated tissue rather than ejection from the surface. [Work supported by NIH EB007643, NIH DK043881, and NSBRI through NASA NCC 9-58.]
Linear and log frequency rippled spectra
Authors: Yost William , Zhong Xuan , Najam Anbar
Published: May 2014

Roy Patterson’s Ph.D. dissertation investigated the pitch-shift of the residue and pitch perception has been a significant topic of interest to Roy ever since. I had the good fortune of collaborating with Roy on several studies involving pitch perception, especially on what we called regular interval stimuli (RIS), most notably iterated rippled noise (IRN). In addition to IRN stimuli which are characterized as stimuli with regularly spaced spectral peaks and valleys on a linear frequency axis, many studies have investigated stimuli that have regularly spaced spectral peaks and valleys on a logarithmic axis. Both set of stimuli produce a timbre/pitch-like sound quality. In some cases the sound quality of the two types of stimuli are difficult to perceptually separate. While RIS models of pitch processing (e.g., autocorrelation-based models) can account for many of the IRN pitch data, it is not clear what mechanisms produce the timbre/pitch-like qualities of log-frequency, rippled-spectra stimuli. The current paper involves three experiments designed to better understand auditory processing of rippled-spectra stimuli in order to determine if there may be some common perceptual elements that underlie the perception of such stimuli. [Research supported by the AFOSR.]
Frequency selectivity and the auditory filter
Authors: Oxenham Andrew J.
Published: May 2014

Roy Patterson and Brian Moore laid the foundations for our modern understanding of frequency selectivity in the human auditory system and have defined and later refined the measurement and the modeling of the auditory filter. Although the auditory filter is a theoretical construct, the frequency selectivity it represents is thought to reflect the filtering in the cochlea. This talk will review recent work on comparing behavioral measures of the auditory filter with physiological measures of cochlear tuning in humans and other species. Although there are clear pitfalls in using linear systems analysis to characterize an inherently nonlinear system, such as the cochlea, the results suggest that the framework established by Patterson, Moore and their colleagues provides robust estimates of frequency selectivity that are consistent with more direct physiological measurements of cochlear tuning. [Work supported by NIH grant R01DC012262.]
The relationship between speaker size perception and the auditory filter
Authors: Irino Toshio , Patterson Roy D.
Published: May 2014

When we hear a new voice on the radio, we can tell whether the speaker is an adult or a child. We can also extract the message of the communication without being confused by the size information. This shows that auditory signal processing is scale invariant, automatically segregating information about vocal tract shape from information about vocal tract length. Patterson and colleagues have performed a series of experiments to measure the characteristics of size/shape perception [e.g., Smith et al., J. Acoust. Soc. Am. 117(1), 305–318 (2005)], and provided a mathematical basis for auditory scale invariance in the form of the stabilized wavelet-Mellin transform (SWMT) [Irino and Patterson, Speech Commun. 36(3–4), 181–203 (2002)]. The mathematics of the SWMT dictates the optimal form of the auditory filter, insofar as it must satisfy minimal uncertainty in a time-scale representation [Irino and Patterson, J. Acoust. Soc. Am. 101(1), 412–419 (1997)]. The resulting gammachirp auditory filter is an asymmetric extension of the earlier gammatone auditory filter—one which can explain the level dependence of notched-noise masking. Thus, although it is not immediately intuitive, speaker size perception and auditory filter shape are both aspects of a larger, unified framework for auditory signal processing.
Brain imaging the activity associated with pitch intervals in a melody
Authors: Patterson Roy D. , Uppenkamp Stefan , Andermann Martin , Rupp André
Published: May 2014

Early attempts to locate brain regions involved in pitch processing employed sequences of notes with no pitch, fixed pitch, and melodic pitch. They revealed a region of Heschl’s gyrus lateral to primary auditory cortex where sequences with pitch produced more activity than noise, and regions where melody produced more activation than fixed pitch (in planum polare and the superior temporal sulcus). Subsequent research has focused on the fixed pitch region in Heschl’s gyrus and the degree to which the activity is pitch specific. Recently, MEG techniques have been developed to compare the responses to sequences of notes as they occur within bars of music, and to separate current sources associated with attention to melody. This paper illustrates how the techniques can be used to investigate the hierarchy of pitch and melody processing as it occurs in four bar phrases with brass instruments. The experiments show that a given note elicits a larger response when it is part of a melody and the increment is associated with a source beyond auditory cortex. The paper shows how we might track the responses to orchestral instrument sounds presented in a musical context as they proceed through auditory cortex and beyond the temporal lobes.
Quantitative ray methods for scattering by tilted cylindrical shells
Authors: Marston Philip L. , Morse Scot F.
Published: May 2014

Starting with a review of ray methods and phenomena associated with high frequency scattering by spheres and cylindrical shells in water viewed broadside, generalizations to tilted shells will be summarized. These extensions were found to be useful for meridional as well as helical ray backscattering enhancements associated with leaky (or supersonic) waves on shells [Morse and Marston, J. Acoust. Soc. Am. 112, 1318–1326 (2002); Blonigen and Marston, J. Acoust. Soc. Am. 112, 528–536 (2002)]. For such enhancements Fermat’s principle is useful for identifying ray paths of interest. In the case of helical waves (and in the broadside special case), the scattering amplitude can be expressed in terms of a Fresnel patch area where the guided wave is excited on the shell. Fresnel patches also give insight into the relatively large magnitude of meridional ray contributions. The coupling coefficient is proportional to the radiation damping of the leaky wave on the shell and in some cases it is necessary to take into account the anisotropy of the phase velocity. Computational benchmarks include scattering into the meridional plane by tilted infinite cylinders. Related phenomena include enhancements from subsonic guided waves and applications to sonar imaging and time-frequency analysis. [Work supported by ONR.]