bluuebunny/crossref_metadata_2025 huggingface dataset:
Three-dimensional space sound absorbers using microperforated panels
Authors: Sakagami Kimihiro , Toyoda Masahiro , Yairi Motoki , Okuzono Takeshi
Published: November 2016

A microperforated panel (MPP) is one of the most promising alternatives of the next-generation sound absorbing materials. It has a large potential for various use. However, its conventional use is to place it with a rigid-back wall and an air-cavity in-between. Therefore, its arrangements in a room are limited on to room boundaries, and in some cases, this may cause a problem in room design and its strength: for example, in Japan, it is not allowed by regulation to use it for a wall. Therefore, the authors have been looking at the possibility for using MPPs for space sound absorbers without any backing structure. This can allow MPPs for wider use: a three-dimensional shape MPP space absorbers can be easily produced if a suitable material is used. They can be placed easily in various places: they can be put on the floor or hang from the ceiling, etc. Besides, MPPs can be made of designable, lightweight materials, which can add designability to the absorbers. In this paper, the main results of our studies on three-dimensional MPP space absorbers (mainly cylindrical and rectangular three-dimensional MPP space absorbers) are introduced and summarized.
Explosion energy estimates based on propagation modeling of observed infrasound airwaves
Authors: Kim Keehoon , Rodgers Arthur
Published: November 2016

Energetic explosions in the atmosphere produce blast waves, which propagate as infrasound (low-frequency sound waves) and can be detectable at long ranges. Numerous empirical models have been developed to relate explosion energies of events (in terms of trinitrotoluene-equivalent yield) to the metrics of observed infrasonic signals (e.g., peak amplitude, period, and impulse per unit area). However, the existing empirical models often do not take into account variability of atmosphere (e.g., temperature, pressure, and wind) and an empirical model determined in a certain meteorological specification may not be valid in another weather scenario. In this case, unmodeled propagation effects can compromise the accuracy of source energy estimates. We propose another approach to determine explosion energy based on numerical simulations. Infrasound propagation in a given meteorological circumstance is simulated by a full 3-D finite difference method providing accurate Green's functions between the source and receivers. With the numerical Green's functions full-waveform inversion of infrasonic signals is performed to obtain the source time history of the event, and the metrics of the acoustic source time function are related to the energy of explosion source. The technique is applied to controlled chemical explosions and volcanic explosions for verification.
ARISE project capabilities for hazards monitoring
Authors: Blanc Elisabeth , Brachet Nicolas , Le Pichon Alexis , Marchetti Emanuele , Farges Thomas , Ripepe Maurizio , Mialle Pierrick , Husson Philippe
Published: November 2016

The ARISE (Atmospheric dynamics InfraStructure in Europe) project funded by the European Union combines the International infrasound monitoring system developed for the CTBT (Comprehensive nuclear-Test-Ban Treaty) verification, the NDACC (Network for the Detection of Atmospheric Composition Changes) lidar network, European observatories at mid latitudes (OHP observatory), tropics (OPAR observatory), high latitudes (ALOMAR), the European infrasound stations and satellites for the study of the dynamics of the atmosphere from ground to thermosphere. The ARISE network is unique by its coverage from equatorial to polar regions and the involved scales both in time (to tens of years) and space (one to thousands of kilometers). One of the major objective of ARISE is the monitoring of extreme events including lightning, earthquakes, tornadoes, and volcanoes. A review of the ARISE results will be presented. Volcano monitoring by the infrasound technology presents a strong interest for aviation safety in case of eruption of distant non instrumented volcanoes in broad coverage in complement to satellite observations, which can be limited by the cloud cover. One of the ARISE objectives is to provide eruption notifications including confidence index representative on propagation conditions and additional analysis results. Such studies interest the VACCs (including VAAC Toulouse) and the IAVWOPSG.
Seven years of infrasound monitoring of volcanic eruptions of Sakurajima
Authors: Lee Hee-il , Che Il-Young , Garces Milton
Published: November 2016

Korea Institute of Geoscience and Mineral Resources (KIGAM) is operating an dense infrasound array network which is comprised of eight seismo-acoustic array stations (BRDAR, YPDAR, KMPAR, CHNAR, YAGAR, KSGAR, ULDAR, and TJIAR) and we are continuously monitoring all the natural and artificial infrasonic events occurred in and around Korean peninsula with this network. Sakurajima volcano is one of the most active volcanoes in the world to the point where the Volcanic Ash Advisory Center in Tokyo issued 6,012 warnings over the past 7 years from 2009 to 2015. We have checked and analyzed all the infrasound signals possibly associated with the eruptions chronology of Sakurajima volcano based on the Tokyo VAA (Volcanic Ash Advisories) information, in order to know how daily, seasonal and yearly atmospheric changes affect the detection capability of each infrasound station. The result of preliminary analysis will be presented and how the geographical location of the infrasound network which is fan-shaped to the Sakurajima volcano is affected by stratospheric wind dynamics will be discussed.
Interactions between intermittent gravity waves and infrasounds
Authors: Millet Christophe , Ribstein Bruno , Lott Francois
Published: November 2016

Infrasound propagation modeling requires accurate wind speed and temperature gradients. Even though the accuracy of atmospheric specifications is constantly improving, it is well-known that the main part of gravity waves is not resolved in the available data. In most infrasound modeling studies, the unresolved gravity wave field is often represented as a deterministic field that is superimposed on a given average background state. Direct observations in the lower stratosphere show, however, that the gravity wave field is very intermittent, and is often dominated by rather well-defined wave packets. These observations suggest that the vertical spectra are likely to result from ensemble averages of quite narrow-banded periodograms. In this study we sample the spectrum by launching few monochromatic waves and choose the gravity-wave properties stochastically to mimic the intermittency. The statistics of acoustic signals are computed by decomposing the original signal into a sum of modal pulses. Owing to the disparity of the gravity and acoustic length scales, the interaction can be described using a multiple-scale analysis and the appropriate amplitude evolution equation involves certain random terms that are related to the gravity wave sources. More specifically, it is shown how the unpredictable low-level small-scale dynamics triggers multiple random stratospheric waveguides in which high frequency infrasound components can propagate efficiently.
Localization-based audiovisual speech-recognition benefit with degraded spatial cues
Authors: Sheffield Sterling W. , Wheeler Harley J. , Brungart Douglas S. , Bernstein Joshua G.
Published: November 2016

Degraded sound-localization accuracy is usually associated with reduced spatial awareness, but can also lead to reduced speech intelligibility in cases where audiovisual speech cues are available from a talker in an unknown location. Previous work showed that sound-localization cues improved speech perception for bilateral cochlear implantees by helping them face the talker of interest in a multitalker environment. This study evaluated the degree of localization accuracy required to obtain an audiovisual benefit. Normal-hearing adults used auditory localization cues to orient their gaze toward a video of a target talker. The target-talker location varied randomly among four azimuths spanning 180°. Auditory-localization cues were parametrically degraded with a real-time hearing-loss simulator without affecting auditory speech-recognition performance. Results revealed a maximum audiovisual benefit for speech recognition in noise of 5 dB, diminishing to zero with increasing localization degradation. Head tracking verified the reduction in localization accuracy with increasing degradation. Results were compared to data on traditional broadband-noise localization accuracy. This analysis suggested that listeners with hearing loss, cochlear implants, or wearing hearing protection would need to be able to localize sounds within 35 (∼50% of the separation between talkers) to obtain at least some visual benefit from a talker in an unknown location.
Head movement in human sound localization
Authors: Sato Hayato , Morimoto Masayuki , Sato Hiroshi
Published: November 2016

The aim of the present research is to optimize acoustic guide signals for visually impaired persons. The signal must be localized in the correct direction by the impaired person, since they aid their safe movement. Generally speaking, head movements increase localization accuracy of continuous sound. First, we clarified whether or not the effect of head movement appears in sound localization of intermittent sound in place of continuous one. Localization tests showed that effectiveness of head movements persist even if the sound is intermittent rather than continuous. However, investigations have not yet been carried out to make it clear whether or not spontaneous head movements occur at all during natural sound localization, although the previous studies were premised on the movements. If the movements always occur spontaneously, we could expect greater flexibility on designing acoustic guide signals. Second, we discussed directly whether or not spontaneous head movements occur during natural sound localization. Localization tests showed that spontaneous head movements occur during sound localization; however, they do not always occur.
Factors influencing auditory localization by moving listeners
Authors: Brungart Douglas S. , Kwiatkowski Tricia , Kruger Sarah E. , Heil Thomas
Published: November 2016

Previous results have shown that observers who are walking at a constant pace on a treadmill are able to localize continuous sound sources and acquire and identify audiovisual targets more quickly than observers who are standing on a stationary platform, with no apparent loss in accuracy. In order to better understand the conditions where self-motion might enhance localization performance, a follow-on experiment was conducted that measured localization accuracy with sounds of three different durations (250 ms, 1000 ms, and continuous) under four different movement conditions (standing on a stationary platform, standing on a moving platform, walking on a treadmill at a self-paced rate, and walking on a treadmill at a constant rate). Localization accuracy was also measured both standing and walking when spatial cues were degraded by the use of a hearing protection device. As expected, the results suggest that short sounds are localized less accurately than long-duration sounds. However, preliminary results also suggest that walking at a constant pace may provide a greater benefit for localization than self-paced walking. The results are discussed in terms of the possible dynamic localization cues listeners might have access to when they are moving relative to the location of a distant sound source. [Work supported by MRMC Grant W81XWH-12-2-0068; The opinions presented are the private views of the authors and are not to be construed as official or as necessarily reflecting the views of the Department of Defense.]
Effects of source- and head-motion on auditory perceptual organization
Authors: Kondo Hirohito M. , Pressnitzer Daniel , Toshima Iwaki , Kashino Makio
Published: November 2016

The perceptual organization of auditory scenes needs to parse the incoming flow of acoustic inputs into perceptual streams. It is likely that cues from several modalities are pooled for auditory scene analysis, including sensory-motor cues related to the active exploration of the scene. We show effects of source- and head-motion on auditory streaming. In a streaming paradigm, listeners hear a sequence of repeating tone triplets and indicate their perception of one or two subjective sources called streams. We used a robotic telepresence system, Telehead, to disentangle the effects of head motion: changes in acoustic cues at the ear, subjective location cues, and motor cues. We found that head motion induced perceptual reorganization even when the auditory scene had not changed. We further analyzed the data to probe the time course of sensory-motor integration. Motor cues impacted perceptual organization earlier and for a shorter time than acoustic or subjective location cues, with successive positive and negative contributions to streaming. An additional experiment showed that arm or leg movements did not have an impact on scene analysis. Our results suggest a loose temporal coupling between the different mechanisms involved.
Efficient physics based simulation of spatial audio for virtual and augmented reality
Authors: Duraiswami Ramani , Zotkin Dmitry N.
Published: November 2016

Many applications in spatial hearing are being enabled by the virtual and augmented reality revolution. Because of these there has been a tremendous improvement in the quality of head mounted displays, and the availability of tracking (3 DOF and 6 DOF) in an integrated environment with headphones suitable for binaural rendering. While these devices were initially focused on creating visual representations of the 3D world (in the case of VR) or a visual representation of artificial 3D objects overlaid on the real world (in the case of augmented reality), it was soon realized that unless the audio provided a degree of spatial realism that complemented the visual and was consistent with it, the sense of immersion crucial to maintaining the illusion was lost. In this talk, I will describe the engine for creating virtual simulations in real time that incorporates head motion, environmental reverberation, room materials, as well as generic or individual HRTFs. Trade-offs that allow the engine to work on architectures ranging from single core CPUs, to mobile devices to high end multicore devices will be discussed. In contrast to these “object-based” representations of spatial auditory objects, there has also been a revival in approaches based on expanding the sound-field in low order ambisonics representations, and their subsequent binaural rendering. After providing a description of the optimizations made in our engine, we discuss future work.
Possibility of binaural production by means of bone conduction actuators
Authors: Qin Xiuyuan , Usagawa Tsuyoshi
Published: November 2016

A pair of bone conduction actuators is used for music reproduction as replacement of headphone. Because of strong inter-aural coupling, it is though the stereophonic reproduction is not easy to realize by bone conduction actuators. Haim Sohmera, et al. 2000, reported that “there is no need to vibrate bone in order to obtain 'bone conduction' response.” They have shown a fluid pathway from bone to ear. The coupling between left and right side stimuli by bone conduction actuators set at head-of-mandible or mastoid is occurred not only due to bone but also fluid. On the other hand, when we are listening the music by bone conduction actuators, we can enjoy the some extent of special image, at least some extend of lateralization. The authors are examined the possibility of binaural production by means of inter-aural time and intensity trading using a pair of bone conduction actuators. Results of psycho-acoustical experiment indicate that the trading phenomenon between time and intensity is observed around 1000 Hz even if the results are not stable.
Identification the vibroacoustic properties of sandwich-composite panels from wavenumber measurements
Authors: Atalla Noureddine , Cherif Raef , Burns Gary
Published: November 2016

This paper investigates the identification of the vibroacoustic properties of sandwich composite panels from structural wavenumber measurements over a large frequency band. Several indicators are investigated including the modal density, damping loss factor, radiation efficiency, and sound transmission loss. The accuracy of the identified indicators is studied by comparison with several direct and indirect measurements and analytical predictions. Results show that all identified indicators are in good agreement with measurements and theory for the studied constructions.
Sound radiation from unbaffled vibrating plates, using an edge-diffraction based approach
Authors: Martín Román Sara R. , Svensson U. Peter , Savioja Lauri , Smith Julius O.
Published: November 2016

The sound radiation from unbaffled vibrating plates is a classical problem that is often solved numerically by coupling a vibration model to the surrounding air with the boundary element method, or the finite differences in the time domain (FDTD). Here, the surrounding air is instead represented with Green's functions computed with the edge source integral equation (ESIE) [Asheim and Svensson, JASA 133, pp. 3681-3691, 2013]. Expressions are derived for the analytical edge directivity functions in the ESIE for the special case of a thin flat plate with sources on both sides of the plate, of opposite polarity. Frequency-domain as well as time-domain results are presented, for specified vibration patterns, including an unbaffled piston. The coupling of the Green's functions to an FDTD model of the plate vibration is outlined. The singularity issues that appear with the ESIE for certain radiation directions are handled using a recent hybrid approach [Martín et al., J. Acoust. Soc. Am. 139, 2202 (2016)] where the ESIE is used to calculate the sound pressure on the surface of the radiator, followed by the same propagation stage as in the boundary element method. This approach offers a computationally efficient method, and the time-domain version makes auralization straightforward.
Quantification of disorder sensitivity of a subordinate oscillator array
Authors: Sterling John A. , Vignola Joseph , Glean Aldo , Ryan Teresa
Published: November 2016

Recent research has shown that arrays of small dynamic elements attached to a larger, primary structure can be tuned to significantly alter the time and frequency response of the system. Often referred to as “fuzzy structures,” such subordinate oscillator arrays have applications including damping, radio frequency filtering, energy harvesting, micro electromechanical systems, and chemical vapor sensing. This work shows that an attached array adds damping and demonstrates a distinct rejection band in the spectral response.The subordinate system here is an array of cantilever beam attachments with a range of isolated natural frequencies that surround a target band. Small errors in the distributions of masses and stiffnesses of the attachments can have a significant degrading effect on desired response. Error on the order of 0.1% can be significant. This paper discusses experimental verification of this phenomena. In the experiment, small amounts of mass were added to the tip of both individual and combinations of the cantilevers to deliberately deviate from the design. The resultant responses were recorded. A direct relationship between perturbed mass and frequency distributions and response deviation will be shown.
Thermoacoustic power sensors: Principles and prediction
Authors: Dumm Christopher M. , Vipperman Jeffrey S. , Carvajal Jorge V. , Walter Melissa M. , Czerniak Luke , Ruane Amy S. , Ferroni Paolo , Heibel Michael D.
Published: November 2016

Thermoacoustic Power Sensor (TAPS) technology can be used to wirelessly measure the temperature and radiation flux conditions in a nuclear reactor core. A TAPS is a self-powered, standing-wave thermoacoustic engine, enclosed in a cylinder, and placed in the reactor core (for example, inside instrumentation tubes). TAPS utilize heat from a radiation-powered heater and cooling from the reactor core coolant to generate acoustic waves; these waves have amplitude proportional to the local radiation flux and frequency proportional to the local coolant temperature. The acoustic waves propagate physically into the reactor coolant and structure, and are detected with receivers (e.g. accelerometers) placed on the outside of the reactor vessel. TAPS signals are interpreted (and the reactor state conditions measured) by comparison of the received signals to a reference generated by predictive modeling. Since TAPS are wireless and self-powered, they offer advantages in safety (e.g., by reducing the required number of vessel penetrations) and in maintenance reduction. Since TAPS contain no internal electronics, they are particularly well-suited to high-temperature, fast radiation environments for which no in-core instrumentation currently exists, such as in sodium-cooled fast reactors (SFRs). A methodology for predictive modeling of TAPS signals is discussed and evaluated experimentally.
The control of resonance curve using the shape modulation of the scattering region in elastic waveguide
Authors: Naito Yoshimasa , Kato Hatuhiro , Ishii Takaaki
Published: November 2016

This study focuses on the control of Fano resonance in the elastic plate, which is initially developed in atomic scattering and has been seldom to discuss. Fano resonance is a phenomena involved by the localized/quasi-localized wave, in which the resonance curve becomes asymmetric due to the phase difference between the incident wave and the localized wave. The typical resonance curve available in the system is the frequency dependence of the reflectance under the scattering problem. We will demonstrate that the controllability of the resonance curve using various shapes of the scattering region under the simulation and experiment. The experiment system is an elastic waveguide made of aluminium plate and the scattering region is formed by modulating the plate thickness. The localized wave is induced by incident wave in the thinned scattering region and causes the wave tail that penetrates into the lead region of waveguide. The controllability can be realized by the overlap of the wave tail and the incident wave. For analyzing the experiment data, we also develop the method to extract S-parameters. The controllability was already confirmed by the preliminary experiment. Now, we are preparing verify various shapes of the scattering region for detail experiments.
Spoken and non-verbal interaction experiments with a social robot
Authors: Beskow Jonas
Published: November 2016

During recent years, we have witnessed the start of a revolution in personal robotics. Once associated with highly specialized manufacturing tasks, robots are rapidly starting to become part of our everyday lives. The potential of these systems is far-reaching; from co-worker robots that operate and collaborate with humans side-by-side to robotic tutors in schools that interact with humans in a shared environment. All of these scenarios require systems that are able to act and react in a social way. Evidence suggests that robots should leverage channels of communication that humans understand—despite differences in physical form and capabilities. We have developed Furhat—a social robot that is able to convey several important aspects of human face-to-face interaction such as visual speech, facial expression, and eye gaze by means of facial animation that is retro-projected on a physical mask. In this presentation, we cover a series of experiments attempting to quantize the effect of our social robot and how it compares to other interaction modalities. It is shown that a number of functions ranging from low-level audio-visual speech perception to vocabulary learning improve when compared to unimodal (e.g., audio-only) settings or 2D virtual avatars.
Time delay estimation of broadband acoustic signals and its defense applications
Authors: Ferguson Brian G. , Scanlon Michael V. , Chang Jay W.
Published: November 2016

The measurement of the difference in the times of arrival (or time delay) of an acoustic signal at two spatially separated sensors is fundamental to localizing its source. For continuous broadband signals, the time delay is best estimated by the generalized cross-correlation of a pair of sensor outputs. The lag at which the generalized cross-correlation function reaches its maximum value provides an estimate of the time delay. Generalized cross-correlograms are presented for sensor output data recorded at sea on a submarine. The correct peak is readily identified by cross-correlating the conventional (and also the adaptive) beamformer outputs of a pair of widely-spaced arrays, rather than the outputs of two single hydrophones with the same separation distance (66.3 m). Similarly, the use of various prefiltering methods is shown to suppress secondary (ambiguous) peaks in the cross-correlogram. This approach is then extended to include mechanical and biological underwater acoustic transient signals with the time delay estimates being used to locate the source using the principle of passive ranging by wavefront curvature. Finally, the role of time delay estimation in the localization of aircraft, ground vehicles, and weapon fire using unattended land-based acoustic surveillance systems is demonstrated using real data.
Phase shifts in passive fathometer processing
Authors: Michalopoulou Zoi-Heleni , Gerstoft Peter
Published: November 2016

In passive fathometer processing, the presence of wavelets/sincs in the estimate of the medium's Green's function corresponds to the location of reflectors in the seabed; the amplitudes of the wavelets point to properties of the reflecting layers. Particle filtering has been successful in tracking reflectors that define layer interfaces from data from the Boundary 2003 Experiment after both conventional and MVDR processing. Further working on the problem, however, revealed that phase shifts may be present in the wavelets of the Green's function, which hinder accurate layer identification if unresolved. In this work, using a process similar to time delay estimation, we identify and model these shifts and demonstrate the significance of their modeling in accurate reflector identification as well as accurate estimation of reflector strengths. [Work supported by ONR.]
Analysis of a baffled circular array to avoid ambiguity in detection of arrival estimation
Authors: Bozzi Fabricio A. , Filho William S. , Monteiro Fernando P. , Silva Fabio O. , Barreira Leonardo M.
Published: November 2016

The number of sensors present in an array imply in cost, length, weight, and computational complexity. So, it is desired that an array satisfies its project purpose using the minimum of elements. In this study, we analyze the characteristics of a uniform circular array (UCA). Previous studies show the ambiguity problem when working with only few sensors. The grating lobes and potentials ambiguities in uniform linear array are generally avoided limiting the space between sensors in half of the wavelength. In UCA, these problems are solved also by limiting the space between sensors using an adequate number of sensors for a given radius or changing the radius for a given number of sensors. This study shows that it is possible to avoid the grating lobes controlling the sensor's directivity. The directional gain model is used to represent a realistic baffled vertical stave, three hydrophone each, and the Multiple Signal Classification (MUSIC) is applied to detect sources. Simulation results show the accuracy when using directives sensors. This array is analyzed here, working with experimental data, acquired in an acoustic tank.
Acoustic distance measurement based on the interference between transmitted and reflected waves using cross-spectral method by introducing analytic signal of linear chirp sound
Authors: Nakasako Noboru , Honda Shinya , Shinohara Toshihiro , Nakayama Masato , Uebo Tetsuji
Published: November 2016

The distance to a target is fundamental information in many engineering applications. Recently, an acoustic distance measurement (ADM) method has been proposed based on the interference between transmitted and reflected waves, but it requires two applications of the Fourier transform. The ADM method in which a linear chirp whose frequency changes linearly with lapse of time is adopted as a transmitted sound has been also proposed. However, due to the influence of the measuring system from the loudspeaker to the microphone, the ADM would often estimate the spurious short distance different from true distance. This paper describes a fundamental study on the ADM method by applying the cross-spectral method to observed signals of the adjacent two-channel (2ch) microphones, adopting a linear chirp as transmitted wave and removing the influence of the measuring system. More concretely, though the linear chirp in a time domain corresponds to the frequency spectrum in a frequency domain, it is not a complex signal but a real signal. To apply the cross-spectral method, the analytic signal of linear chirp is introduced. We confirmed the validity of the chirp-based ADM method by performing a computer simulation and by applying it to an actual sound field.
Signal processing challenges for reconstructing NASA's Apollo missions to the moon
Authors: Oard Douglas W. , Hansen John H.
Published: November 2016

During the Apollo Program, NASA recorded dozens of audio channels to document the coordination activity in the Apollo Mission Control Center. We have digitized these recordings for the entire Apollo 11 mission, but several challenges arise when seeking to use these unique recordings for mission reconstruction. One is that 50 of the 56 recorded channels contain headset audio that documents the mix of radio and intercommunication “loops” that an individual flight controller actually heard. Reconstructing the audio that was available for selection therefore requires multi-channel source separation. The same loop might be recorded on multiple time-synchronized channels, and the some known speakers routinely speak only on certain loops, so a considerable amount of side information is available for this source separation task. Second, several additional audio channels are available from different recorders, notably including recordings made aboard the two Apollo spacecraft). Integrating these additional channels requires content alignment techniques, which can leverage both speech content and incidentally recorded non-speech signals. Third, we have only limited metadata for each channel, indicating (for example) which headset audio was intended to be recorded on that channel and who (by name) might have used that deadest. Signal processing techniques can help to enrich that metadata, helping (for example) to recognize speaker changes associated with shift changes or specific mission events.
Video semantic indexing and localization
Authors: Shinoda Koichi
Published: November 2016

Nowadays Internet traffic has been largely occupied by consumer video but most of them are not accompanied with text tags for search. Hence, video semantic indexing, which extracts visual concepts such as objects, scenes, and actions directly from video contents, has been intensively studied. Fundamentally, this task consists of two problems: localization and recognition. While until recently these two problems have been studied independently, emerging end-to-end deep learning techniques using convolutional neural networks (CNNs) and recurrent neural networks (RNNs) offer effective ways to solve them simultaneously. These techniques are deeply related to spoken word detection techniques in the speech field. In this talk, we overview the recent progress in this area and discuss potential directions for future research.
Spatiotemporal variation in habitat utilization of humpback dolphins (Sousa chinensis) potentially affected by freshwater discharge
Authors: Lee Chia-Yun , Lin Tzu-Hao , Akamatsu Tomonari , Chou Lien-Siang
Published: November 2016

Dynamics of habitat utilization of marine mammals are important for the conservation management of coastal ecosystems. Previous studies have shown that seasonal changes of humpback dolphin distribution are associated with seasonal changes of upstream rainfall. However, temporal variations of dolphin behavior at an estuarine habitat remain unclear. In this study, echolocation clicks of humpback dolphins were recorded at the Xinhuwei River Estuary, western Taiwan, between July 2009 and November 2015. Sound source bearing angles to identify different sound sources, intensity, and inter-click intervals (ICIs) as an index of the sensing distance were measured to investigate the sensing and movement of dolphin groups. Humpback dolphins searched for shorter sensing distances and moved back and forth near the estuary during spring and summer, which suggests foraging-related behaviors were much frequently observed during wet seasons. However, humpback dolphins changed to focus on longer detection ranges (ICIs changed from 40 to 50 ms to 50 to 70 ms) and move in straight forward when upstream rainfall increased during this period. The present result indicated the dynamics of habitat utilization of humpback dolphins at an estuary is likely driven by the distribution and abundance of prey resource which is influenced by the temporal change of river runoff.
Quantitative measurements of seismic airgun reverberation in the shallow-water Beaufort Sea
Authors: Thode Aaron , Guerra Melania , Blackwell Susanna , Macrander A. Michael
Published: November 2016

Shallow-water airgun survey activities off the North Slope of Alaska generate impulsive sounds that have been the focus of much regulatory attention. Reverberation from repetitive airgun shots, however, also increases the background noise levels, which can decrease the detection range of nearby passive acoustic monitoring (PAM) systems and potentially mask communication signals between animals. Typical acoustic metrics for impulsive signals provide no quantitative information about reverberation. Two metrics are suggested here for quantifying reverberation: a “minimum level” metric that measures reverberation levels between airgun pulse arrivals, and a “reverberation metric” that estimates the relative magnitude of reverberation vs. expected ambient levels in the hypothetical absence of airgun activity, using satellite-measured wind data. The metrics were applied to acoustic data measured by autonomous recorders in the Alaskan Beaufort Sea in 2008. They demonstrate how a 3000 cu. inch seismic survey in 50 m deep water can increase the background noise over natural ambient levels by 30-45 dB within 1 km of the activity, by 10-25 dB within 15 km of the activity, and by a few dB at 128 km range. Shallow-water reverberation can thus substantially reduce the performance of PAM systems several kilometers of shallow-water seismic surveys. Other impulsive activities such as pile driving may face similar issues.
Effects of anthropogenic noise on migrating bowhead whales in the Beaufort Sea
Authors: Kim Katherine H. , Blackwell Susanna B. , Thode Aaron M.
Published: November 2016

Greeneridge Sciences, Inc. (Greeneridge), has conducted multi-year, underwater, acoustic measurements at two study areas offshore of the North Slope of Alaska in the Beaufort Sea. The primary objective of these studies was to measure industrial sounds, e.g., those produced by oil production, seismic exploration, and drilling activities, and to assess their potential effects on the behavior of bowhead whales during their annual fall migration. To meet this objective, during open-water season every year from 2001 to 2016 (BP, Hilcorp) and 2007 to 2014 (Shell), Greeneridge deployed passive acoustic recorders equipped with directional sensors (DASARs) along the continental shelf. Over the course of these studies, millions of bowhead calls were localized, while ambient noise and various types of anthropogenic noise, such as tonal sounds associated with machinery and vessels and seismic airgun pulses, were quantified. The localization capabilities of the DASARs, large numbers of observations, and multi-year time series measurements together permitted, with high statistical power, quantitative evaluation of the effects of anthropogenic noise on bowhead behavior. Here, we’ll review some of our major findings, including the apparent displacement of calling bowhead whales and changes in their calling rate in response to industrial activities, consistency in their call source levels, and a shift in the frequency content of their call repertoire. [Work supported by BP Exploration Alaska, Shell Alaska Venture, and Hilcorp Alaska.]
Predicting masking by impulsive noise sources: An experimental evaluation
Authors: Sills Jillian M. , Southall Brandon L. , Reichmuth Colleen
Published: November 2016

Impulsive noise sources pose significant challenges in terms of predicting auditory masking using conventional methods. Aside from their obvious time-varying structure, another complicating factor is the influence of propagation on the spectral and temporal characteristics of the noise, especially in water where such sounds may travel considerable distances. To address this, we developed a psychophysical paradigm to quantify masking in Arctic seals during different time intervals of seismic maskers, which were recorded either close to (1 km) or far from (30 km) an operational air gun array. Signal-to-noise ratios at threshold (50% correct detection rate) were obtained behaviorally for trained seals, and were compared to conventional masked threshold predictions based on average noise levels and critical ratio measurements for the same individuals. The experimental data showed that masking predictions were poorest in the time intervals where noise exhibited the greatest amplitude variation. These findings provide insight into whether and how the dynamic sound field surrounding seismic surveys constrains the ability of seals to detect relevant signals, and show how predictive models of masking for transient noise sources can be improved by incorporating time-based analyses of signals and noise. [Work supported by OGP-JIP.]
Correlation among multipaths for long rang propagation
Authors: Baggeroer Arthur B. , Colosi John A.
Published: November 2016

The multipath arrivals in ocean acoustic tomography are the important observations for the inversion to a sound speed profile and then to temperature. They are also implicit in any matched field processing beamforming. While the covariance of ray path travel times has been examined (Flatte and Stoughton, JGR 91, C6), the correlations among the waveforms of these multipaths has never been determined. There are two conflicting hypotheses: i) the paths radiate from a source, so they must be correlated. ii) Alternatively, the small scale ocean inhomogeneities randomize the paths since they traverse different ocean masses. At short ranges and low frequencies, the paths are correlated, whereas at long ranges and high frequencies, they are uncorrelated. Reality is somewhere in between. We have a power law medium which at large scales correlates paths but decorrelates them at small scales. The key quantity distinguishing the scales is the Fresnel zone extent. We analyze the correlation from two perspectives. A theoretical one based on path integral formulations and a experimental one on numerical Monte Carlo simulations on the massively parallel MIT Lincoln Laboratory LLGrid using adaptive beamforming for path resolution.
Optimisation of ultrasound exposure parameters for extravasation and drug delivery using submicron cavitation nuclei
Authors: Mannaris Christophoros , Grundy Megan , Duffy Margaret , Seymour Len W. , Carlisle Robert , Coussios Constantin C.
Published: November 2016

Sub-micron cavitation nuclei with the ability to passively extravasate through the leaky tumor vasculature have been shown to enhance both extravasation and penetration of pharmaceuticals in tumors. The aim of the present work is to optimize the acoustic parameters and maximize drug delivery mediated by cavitational microstreaming. Either lipid-shell microbubbles, or gas-stabilizing polymeric submicron cups of mean diameter 480 nm are co-administered with a model drug through a flow channel formed in agarose gel. The effect of ultrasound frequency, pressure amplitude, pulse duration, duty cycle, and pulse repetition frequency on the delivery of the drug is first evaluated, using both a single-layer and a dual-layer flow phantom that better represents the leaky tumor vasculature and dense extracellular matrix. The optimal parameters at 0.5 MHz and 1.6 MHz are then selected and used to deliver an oncolytic virus, genetically modified to express the RFP reporter gene, thus allowing the quantification of the delivery, infection, and subsequent spreading of the virus under fluorescence microscopy. We hypothesize that while inertial cavitation within the vasculature leads to extravasation, enhanced penetration is achieved by subsequent cavitation events of the sub-micron nuclei that passively extravasate and propel the drug deeper into the tumor.
Ultrasound-stimulated microbubble enhanced low-dose radiation response
Authors: Czarnota Gregory
Published: November 2016

We have recently demonstrated that mechanical perturbation of endothelial cells from ultrasound-stimulated microbubbles (USMB) results in enhanced tumor radiosensitivity at low 2 Gy doses of radiation. Our hypothesis is that USMB-based endothelial membrane perturbations produce ceramide via a sphingomyelinase (ASMase) pathway, and act synergistically with radiation to enhance overall tumor response. Here, we investigate the role of the SMase-ceramide pathway on USMB-based endothelial radiosensitization. Experiments were carried out in wild type (C57BL/6) and ASMase knockout mice, implanted with a fibrosarcoma line (MCA-129). Animals were treated with radiation doses varying from 0 to 8 Gy alone, or in combination with ultrasound-stimulated microbubbles. Treatment response was assessed with Doppler ultrasound vascularity index acquired at 3, 24, and 72 hrs using a VEVO770 preclinical ultrasound system. Staining using ISEL, ceramide, and CD31 immunohistochemistry of tumor sections was used to complement results. In contrast to wild type animals, ASMase knockout mice, or wild-type mice receiving S1P, were found to be generally resistant to the anti-vascular effects of radiation and USMB. Minimal cell death and no vascular shutdown was observed following treatments in those experimental groups. Overall conclusions drawn from this work suggest a mechanotransduction-like effect that results in endothelial radiosensitization.
High temporal and spatial resolution ultrasonic imaging and application to cardiovascular imaging
Authors: Hasegawa Hideyuki
Published: November 2016

Recently, high frame rate ultrasound has become used for various imaging scenarios. It creates multiple scan lines at the same time using unfocused transmit beam to reduce the number of transmissions per image frame. Consequently, high frame rate ultrasound can realize a frame rate of over 1 kHz, but the lateral spatial resolution is degraded by using unfocused transmit beams, such as plane and diverging waves. To overcome such a problem, we have developed novel beamforming methods based on adaptive procedures, such as phase coherence imaging and minimum variance beamforming. As a result, high temporal and spatial resolution could be realized simultaneously. The developed high frame rate imaging methods were applied to imaging of cardiovascular dynamics. Blood flow in the carotid artery and cardiac left ventricle were imaged at frame rates of 2500 Hz and 6250 Hz with plane wave and diverging wave transmissions, respectively, and vortices in the carotid bifurcation and left ventricle could be observed. The high frame rate imaging method was also applied to tissue motion imaging. In the carotid arterial wall, pulse wave propagation could be visualized clearly even in a very regional segment of about 10 mm. Also, we could also visualize propagation of the shear wave in the liver, which is spontaneously generated by the beating heart and blood vessels, and its propagation speed could be estimated qualitatively. High frame rate ultrasound would be an indispensable technique for measurement of tissue dynamics.
Coherence-based adaptive imaging for high-frame-rate ultrasonic imaging
Authors: Li Pai-Chi
Published: November 2016

Some success has been demonstrated in the studies of adaptive imaging, but these approaches are generally not suitable for high-frame-rate imaging where broad transmit beams are required. This report introduces the signal-to-noise ratio (SNR)-dependent coherence factor (CF), which can be used for adaptive sidelobe suppression in ultrasound (US) imaging. Previous methods employed the minimum-variance-distortionless-response (MVDR)-based CF to achieve remarkable resolution improvement (by MVDR) and to suppress sidelobes (by CF). However, the SNR is often low when using an unfocused acoustic beam, giving such an approach suboptimal performance in these applications since noise also lowers the coherence and thus affects the effectiveness of the sidelobe suppression by these CF-based methods. To overcome this problem, the proposed method takes into account the local SNR in the CF formulation so that the contrast can be restored even when the SNR is low. Simulations show that the proposed method performs well even when the SNR is as low as -10 dB. Compared to the conventional CF, the contrast (CR) and contrast-to-noise ratio (CNR) in clinical US imaging can be improved, e.g., by an average of 27.2% in CR and 11.1% in CNR, with the proposed method.
Pilot in vivo studies on transcutaneous boiling histotripsy in porcine liver and kidney
Authors: Khokhlova Vera , Schade George , Khokhlova Tatiana , Wang Yak-Nam , Simon Julianna , Starr Frank , Maxwell Adam , Bailey Michael , Kreider Wayne
Published: November 2016

Boiling histotripsy (BH) uses millisecond-long pulses of focused ultrasound (FUS) waves with shocks to mechanically homogenize tissue. Here we report a pilot in vivo acute study on transcutaneous volumetric BH ablation of porcine liver and kidney. BH treatment was administered using a 1.5 MHz FUS transducer operating at peak electric power ranging from 0.6 to 4 kW with B-mode ultrasound guidance using an imaging probe mounted coaxially. Sonication protocols delivered 5-30 pulses of 1-10 ms duration and 1% duty factor to focal points spaced 1-1.5 mm apart in a rectangular grid with 5-15 mm linear dimensions. Well-demarcated volumetric BH lesions were successfully generated in both liver and kidney without respiratory gating. The treatment was accelerated 6-fold without affecting the quality of tissue homogenization by using shorter duration BH pulses of larger peak power. These data indicate that transcutaneous volumetric renal and hepatic ablations are feasible in the in vivo porcine model. Studies are ongoing to optimize treatment parameters with the goal of clinical BH ablation of renal and hepatic masses. [This work was supported by NIH R01 EB7643, K01 EB015745, NSBRI through NASA NCC 9-58, RFBR 16-02-00653, and Urology Care Foundation.]