bluuebunny/crossref_metadata_2025 huggingface dataset:
Resonant acoustic nonlinearity of defects: Non-classical manifestations and applications for diagnostic imaging
Authors: Solodov Igor
Published: November 2016

Acoustic nonlinearity of non-bonded interface (Contact Acoustic Nonlinearity (CAN)) is a type of non-classical nonlinearity perspective for applications in non-destructive evaluation of cracked defects. The presence of such defects also leads to a local decrease in rigidity and manifests in a characteristic frequency of the defect. A frequency match between the driving acoustic wave and this frequency provides a Local Defect Resonance (LDR) and an efficient energy delivery from the wave into the defect. A combination of CAN and LDR, therefore, manifests a profound nonlinearity even at moderate acoustic excitation level. Under resonance conditions, a strong enhancement of the higher harmonic (HH) amplitudes is observed. A high quality factor of LDR is also used as a filter/amplifier/resonator for efficient frequency mixing. These “conventional” nonlinear effects are not the only dynamic scenario of nonlinear phenomena for resonant defects. A combined effect of LDR and CAN also results in qualitatively new features characteristic of nonlinear and parametric resonances. Due to parametric instability, nearly total input energy at fundamental frequency can be converted into HH or subharmonic vibrations of the defects. Both super- and subharmonic LDR are strongly localized in the defect area that provides a background for highly-sensitive defect-selective imaging.
The soil plate oscillator: Measuring nonlinear mesoscopic elasticity of granular medium in flexural vibration
Authors: Santos Emily V. , Korman Murray S.
Published: November 2016

The soil plate oscillator apparatus (SPO) consists of two circular flanges (5 inch ID, 8 inch OD, 2.5 inch thick) sandwiching and clamping a thin (1/8 inch) circular elastic acrylic plate. Granular media (soil, masonry sand, glass beads, or even edible granular material) is supported at the bottom by the plate and side walls of the upper flange. A magnetic disk (1 cm) fastened below the plate (on center) is driven by a swept sinusoidal current in a coil placed below the magnet. This electrodynamic SPO, placed in a Wheatstone bridge, was used to measure the on-axis motional electrical impedance Zmot with and without granular loading. Nonlinear tuning curves near resonance exhibit softening with increasing drive amplitude. Measurements of Real{Zmot} and Imag{Zmot} were used to predict the nonlinear mechanical point impedance (Zmech = constant / Zmot) behavior of the SPO system. A lumped element model (granular media and elastic plate system) help determine the mesoscopic nonlinear properties of the granular media alone. Nonlinear tuning curves of the magnet’s acceleration were also measured. A bilinear hysteresis model fits the tuning curve results. See I. T. Perez-Miravete et al., JASA 125, 1302 (2009) for a nonlinear mesoscopic analysis of a flexural bar.
How does the impact strength affect slow time relaxation in rock
Authors: Ostrovsky Lev A. , Lebedev Andrey
Published: November 2016

Earlier we suggested a model for slow time relaxation in rock which is based on the existence of metastable contacts which slowly return to the basic state due to thermal processes. This model allows to explain the logarithmic law of relaxation and estimate the characteristic scale of metastable contacts. In this presentation, along with a brief outline of the problem, we make the next step, namely, describe the dependence of the process on the amplitude of the initial impact. For this, the distribution function of the contacts’ strength is used. Based on the known data, we use the lognormal distribution for the thresholds of contact breakups. In the physically evident case of small percentage of breaking contacts, the excited states’ concentration is shown to linearly depend the impact stress. The latter is in agreement with the known laboratory experiments. We also used the data from the Parkfield earthquake to evaluate the initial strain level (of the order of 10-5) preceding the relaxation. This estimation seems reasonable as compared with data for earthquakes having the magnitude of M6.
Auditory across-channel processing as assessed by monaural and between-ear temporal gap detection tasks
Authors: Kazuhito Ito , Akihide Takamura , Mori Shuji
Published: November 2016

Gap detection is a measure of auditory temporal resolution. Hearing people exhibit acute sensitivity to silent gaps between leading and trailing markers when the two markers are identical or similar in frequency. However, sensitivity to such gaps declines when the two markers are of dissimilar frequencies. To examine the hypothesis that auditory gap detection performance declines during temporal comparisons of activity between different perceptual channels, we conducted monaural and between-ear temporal gap detection tasks. In the latter task, the leading and trailing sinusoidal markers delimiting the gap were presented to separate ears, which are regarded as independent channels, at least up to the superior olivary complex in the auditory brainstem. The between-ear gap detection thresholds were increased, even when the two markers were identical in frequency, and elevated gradually as the frequency difference between the two markers became greater than an octave. Furthermore, the patterns of the across-ear gap detection thresholds were roughly comparable with those of the monaural gap detection thresholds, except when the two markers were identical in frequency. These findings suggest that the different “across-channel” processes assessed by monaural and between-ear gap detection tasks share a common central mechanism for managing temporal information originating from different channels.
Temporal asynchrony and rhythm perception: Neural bases of perceptual asymmetries
Authors: Oxenham Andrew J. , Wojtczak Magdalena
Published: November 2016

Temporal gap detection has been proposed as a perceptual and neural measure of temporal resolution. This measure has not shown strong frequency dependence but, if anything, high frequencies have been found to produce slightly lower (better) thresholds than very low frequencies. In apparent contradiction to these findings, a recent study claimed superior time perception for lower frequencies and proposed the finding as an explanation for why low-frequency instruments typically carry the rhythm in music [Hove et al. (2014), Proc. Natl. Acad. Sci. U.S.A. 111, 10383-10388]. The present study reviewed those findings and replicated them, but found that the results in fact reflect an asymmetry in asynchrony detection, reported earlier, whereby asynchronies are more readily detected when the lower-frequency tone is leading than when the higher-frequency tone is leading [Wojtczak et al., (2012). J. Acoust. Soc. Am. 131, 363-377]. New results using behavioral and EEG approaches reconcile the data from these different studies and confirm that low frequencies do not provide superior temporal resolution. Instead they suggest an asymmetry in how onset asynchronies are perceived, which may have its roots in the acoustic properties of natural sounds and in the mechanics of cochlear filtering. [Work supported by NIH grant R01DC005216.]
Effects of vocal tract inertance on the glottal flow
Authors: Farbos de Luzan Charles P. , Oren Liran , Gutmark Ephraim , Khosla Sid
Published: November 2016

Compressible large eddy simulation is employed to numerically investigate the laryngeal flow. One static model of the canine larynx with a divergent glottis is considered, with the presence of false vocal folds (FVFs). This computational model is developed from empirical data, and compared to similar configurations that do not involve the subject-specific geometrical features. Due to the high enough Reynolds number, the flow is unsteady and develops asymmetric states downstream of the glottis. The intra-glottal vortex structures are formed on the divergent wall of the glottis, immediately downstream of the separation point. The vortices are then convected downstream and characterized by a significant negative static pressure. The FVFs are a main factor in the generation of stronger vortices, and thus on the closure of the TVFs. Models with and without divergent vocal folds are investigated and linked to the existence of vortices. The direct link between the FVFs geometry and the motion of the TVFs, and by extension to the voice production, is of interest for medical applications as well as future research works.
Contextual analysis on geminate/singleton identification difficulties for L2 learners of Japanese based on perceptual features
Authors: Zhang Yanlong , Nakajima Hideharu , Sonu Mee , Kato Hiroaki , Sagisaka Yoshinori
Published: November 2016

It is widely known that Japanese geminate/singleton consonant identification is one of the biggest problems for L2 learners. We have been analyzing identification error characteristics based on their perceptually motivated features. In this presentation, after briefly introducing observed remarkable identification error chracteristics on phonetic context differences with speech rate variations, we have tried to analyze and quantify the difficulties using identification error rates by Japanese beginners of Korean natives. 36 geminate/singleton pairs in 2-5 mora with three speech rates were used for identification experiments. To understand the difficulties quantitatively, objectively measurable acoustic variables such as duration length, loudness and its jumps of the corresponding geminate/singleton consonants were employed to carry out prediction analysis for L2’s identification error rates. Correlation between predicted error rates and observed ones has turned out to be around 0.6 with the speech rates where more identification errors existed. Through these analyses, we could have confirmed that perceptually motivated parameters could provide reasonable and effective explanation in contextual differences of identification errors by L2 learners and its quantification. These results suggest the possibility of effective L2 learning based on perceptual difficulties.
Modeling native phonology and non-native speech perception using electroencephalography signals
Authors: McCloy Daniel , Lee Adrian K.
Published: November 2016

Studies of language learning in adulthood show that learners’ native language phonologies shape their non-native perception and production abilities. Nonetheless, listeners are able to learn to perceive new speech sound contrasts given training. The present study attempts to model how foreign consonants are perceived prior to training or second language study. Brain responses were recorded during passive listening using electroencephalography (EEG), using twelve monolingual English-native listeners and isolated consonant-vowel (CV) syllables read by speakers of several languages (Dutch, English, Hungarian, Hindi, Swahili). To model native-language phonology, EEG responses to native (English) syllables were used to train classifiers based on phonological feature labels for the consonants in each syllable. The trained classifiers were then applied to the EEG responses to foreign syllables, and the classifier outputs used to generate confusion probabilities between each pair of foreign and native consonants for each of the four foreign languages. Confusion matrices based on the EEG classifiers compare favorably to confusion matrices based solely on number of phonological feature mismatches. Ongoing work investigates whether optimal phonological features can be learned from the EEG data using clustering algorithms.
Adaptation to foreign-accented speech with decreased spectral resolution
Authors: Kapolowicz Michelle R. , Montazeri Vahid , Kuang James F. , Assmann Peter F.
Published: November 2016

Listening to foreign-accented speech requires greater effort, and intelligibility is lower than for native speech. We have recently shown that speech processed by a vocoder to simulate reduced spectral resolution imposes a substantial additional cost to intelligibility. The present study investigated perceptual adaptation to foreign-accented speech in conditions with reduced spectral resolution using a 9-channel tone vocoder compared to unprocessed speech. Preliminary results suggest that listeners can quickly adapt to foreign-accented speech with decreased spectral resolution. Native American English listeners achieved performance levels similar to those obtained with initial exposure to the same unprocessed speech from multiple talkers of Mandarin-accented English. However, with increased exposure, performance did not improve to the same degree found for unprocessed foreign-accented speech. Results indicate that the adaptation process is negatively impacted by the interaction of foreign accent and reduced spectral resolution, and suggests that special consideration should be given to the difficulties experienced by listeners with cochlear implants (whose devices provide limited spectral resolution) when they communicate with speakers who have a foreign accent.
Preliminary analysis of training non-native sounds in noise
Authors: Masuda Hinako
Published: November 2016

Past research has repeatedly shown that perceiving speech in non-laboratory environments is challenging for both native and non-native listeners, even if they are able to perform well in laboratory (quiet) environment. However, whether the challenge of non-native listeners’ perception of non-native sounds in noise can be overcome with training has not been fully investigated. The present study reports preliminary analysis of training Japanese learners of English, focusing on the identification of English voiceless fricatives and approximants in multispeaker babble noise, as Japanese learners of English are well-known for having difficulty in accurate perception of such sounds (e.g., Lambacher et al., 2001; Masuda 2016 among others), especially in noisy listening environments. The experiment consists of three sessions: 1) pre-test, 2) training sessions in noise, and 3) post-test. Identification rates of 1) pre- and 3) post-tests will be compared to investigate the effect of 2) training in noise. The effect of English learning experience will also be discussed.
Sleep facilitates talker generalization of accent adaptation
Authors: Xie Xin , Earle F. Sayako , Myers Emily B.
Published: November 2016

Lexically-guided phonetic retuning helps listeners adapt to non-canonical productions produced by a given speaker (e.g., a foreign-accented speaker). Our previous work shows that when tested immediately after training on one accented talker, listeners generalized phonetic retuning only to accented talkers that were acoustically similar to the trained talker. In the present study, we tested whether sleep-mediated consolidation promotes talker generalization to a novel talker who is not acoustically similar to a trained talker in their phonetic realizations. Focusing on word-final alveolar stops, we examined native-English listeners’ 1) adaptation to a trained Mandarin-accented talker and 2) generalization to another untrained Mandarin talker. Participants were tested in a categorization task immediately after training in either the morning or evening and again after twelve hours. Morning and evening groups had comparable performance for the trained talker during the second test, suggesting maintenance of talker-specific learning. Importantly, only evening-trained participants, who had slept before the second test, gained an advantage for the novel talker, whereas morning-trained participants did not improve over the 12 hours in wake state. It is argued that sleep helped listeners to abstract away from specific acoustic properties of the trained talker and thereby facilitated generalization to the novel accented talker.
Developing ultrasound overlay videos for SENĆOŦEN language learners
Authors: Bliss Heather , Bird Sonya , Gick Bryan
Published: November 2016

This paper reports on an initiative to develop a pronunciation training tool for learners of SENĆOŦEN (Salish: Canada). In acquiring new speech sounds, second language learners rely on both acoustic and articulatory information. Ultrasound has been demonstrated to be effective for pronunciation instruction, as it allows learners to visualize tongue movements during speech. However, ultrasound-based instruction can be difficult to implement with large groups or with learners wanting to learn independently. To address these limitations, we developed a technique for creating ultrasound overlay videos which combine ultrasound images of tongue movements with external profile views of a speaker’s head. Ultrasound is particularly useful in SENĆOŦEN, as its inventory includes many lingual articulations that are difficult to distinguish without visual cues, such as velar/uvular contrasts, and a complex coronal series (e.g., ť, ťθ, ʧ, ʃ, ƛ, ɫ, l, ľ). SENĆOŦEN is critically endangered, but efforts are underway to reawaken the language. Children participate in immersion programs, but parents need language-learning opportunities that are adaptable to their schedules and needs. We developed a series of videos for distribution to community members, in particular parents, giving them opportunities to improve their pronunciation to better communicate with their children in their heritage language.
High-frequency seafloor scattering in a dynamic harbor environment: Observations of change over time scales of seconds to seasons
Authors: Weber Thomas C. , Ward Larry
Published: November 2016

Predicting sonar performance in a harbor environment can be made challenging by the dynamics of the upper and lower surface boundaries. In this talk we examine measurements of the seabed in Portsmouth Harbor, NH. Tidally influenced currents in the Piscataqua River make Portsmouth Harbor one of the most challenging commercial ports to navigate in the northeastern United States. The level of interaction between these currents and the harbor floor is a function of the substrate type. Stereo-camera observations in a sand-wave field near the harbor entrance show fluctuations in microscale roughness and optical reflectance at time scales of seconds during periods of high current. Despite the observed microscale dynamics in the sand-wave field, acoustic observations of both high-frequency seabed scattering strength and mesoscale topography in the same area appear stationary over time scales up to seasons. The low-level of observed fluctuations in scattering strength from the sand-wave field are commensurate with the gravel (and presumably less mobile) river thalweg. Nearby bedrock and sand seafloors show similarly low fluctuations over large time scales, despite seasonal variations in benthic fauna.
Underwater threat detection and tracking using multiple sensors and advanced processing
Authors: Acker Timothy W. , Meecham Andy
Published: November 2016

The vulnerability of military installations and critical infrastructure sites from underwater threats is now well accepted and, in order to combat these security weaknesses, there has been growing interest in—and adoption of—sonar technology. The well known challenges of the underwater environment, particularly in a harbor or port setting, can lead to a high Nuisance Alarm Rate (NAR). This, in turn, can lead to a lack of confidence from end users and a possibility that “real” alerts are incorrectly dismissed. In the past, this has been addressed by increasing the capability of individual sensors, leading to ever-increasing sensor complexity, however, the relationship between sensor performance and complexity/cost is highly non-linear. Even with the most complex and capable sensors, the fundamental limit to performance is often limited by acoustics, not sensor capability. In this paper, we describe an alternative approach to reducing NAR and improving detection of difficult targets (e.g., UUV’s), through intelligent combination and fusion of outputs from multiple sensors and data/signal processing algorithms. We describe the statistical basis for this approach, as well as techniques, methodologies and architectures for implementation. We describe the approach taken in our prototype algorithms/system, as well as quantitative and qualitative results from testing in a real-world environment. These results show a significant reduction in NAR and increase in classification/alert range.
Deep learning approach to passive monitoring of the underwater acoustic environment
Authors: Ferguson Eric L. , Ramakrishnan Rishi , Williams Stefan B. , Jin Craig T.
Published: November 2016

A cost effective approach to remote monitoring of protected areas such as marine reserves, harbors and restricted naval waters, is to use passive sonar to detect, classify, localize, and track marine vessel activity (including small boats and autonomous underwater vehicles). This paper uses data from a single hydrophone mounted above the sea floor to compare a conventional cepstral analysis method with a deep learning approach for monitoring marine vessel activity. Cepstral analysis of the underwater acoustic data enables the time delay between the direct path arrival and the first multipath to be measured, which in turn enables estimation of the instantaneous range of the source (a small boat). However, this conventional method is limited to ranges where the Lloyd's mirror effect (interference pattern formed between the direct and first multipath arrivals) is discernible. It is shown that a Convolutional Neural Network (CNN) operating on cepstrum data with a regression output improves the single sensor ranging performance by considering additional multipath arrivals. To demonstrate the effectiveness of the approach, a surface vessel is ranged using the CNN and the results compared with the conventional method.
Blind channel estimation of time-varying underwater acoustic waveguide impulse responses
Authors: Rideout Brendan P. , Nosal Eva-Marie , Host-Madsen Anders
Published: November 2016

Some techniques for underwater passive acoustic localization make use of estimates for the direct and/or interface-reflected acoustic arrival times of a source at one or more underwater hydrophones. This estimation task can be difficult for non-impulsive sources (e.g., humpback whales) due to early arrivals masking later ones. In linear system analysis, the impulse response (IR) of a system is the system output when the input is an impulse (i.e., a short duration, large bandwidth signal), and expresses how a source signal interacts with the environment to yield the output waveform (e.g., that recorded by a hydrophone). Recordings of a relatively impulsive vocalization (e.g., a walrus knock), given that they approximate the IR between the walrus and hydrophone, may facilitate arrival time estimation. IR estimation for unknown, non-impulsive calls is more challenging, particularly for time-varying channels. Blind channel estimation is the process of estimating the set of IRs between a single (unknown) source and multiple receivers, and can potentially help estimate direct and interface-reflected arrival times for non-impulsive marine mammal vocalizations since the IRs can be analyzed rather than waveforms/spectra. In this paper, we use simulations to explore the importance of ocean surface gravity waves on blind estimation of acoustic IRs.
Seasonal acoustic presence of fin and bowhead whales in relation to prey abundance and oceanographic environments in the southern Chukchi Sea
Authors: Tsujii Koki , Otsuki Mayuko , Akamatsu Tomonari , Matsuo Ikuo , Amakasu Kazuo , Kitamura Minoru , Kikuchi Takashi , Miyashita Kazushi , Mitani Yoko
Published: November 2016

To assess how seasonal and ice-associated whales differently respond to the Arctic climate changes, understanding the relationships among their presence and environmental conditions is necessary. We examined the seasonal acoustic presence of fin Balaenoptera physalus and bowhead whales Balaena mysticetus in relation to prey abundance and oceanographic conditions in the southern Chukchi Sea from July 2012 to July 2014 using passive and active acoustic methods. Oceanographic conditions obtained were water temperature, salinity and sea ice concentrations. Fin whale calls were detected from summer to fall, only in ice-free and high prey abundance period. Moreover, the call-detected period was longer in 2013 than 2012. In contrast, bowhead whale calls were mainly detected from fall to winter and in spring, during ice-free and ice-covered periods. The call presence of bowhead whales overlapped less frequently with that of fin whales in fall 2013 than 2012. The reason for the differences in their acoustic presence between these two years may be caused by higher water temperature and late sea-ice formation in 2013 compared to those in 2012. These results suggest that annual variations in the oceanographic conditions possibly affect the distribution of both species in the southern Chukchi Sea.
Snapping shrimp: Changes in environmental noise in Laguna de Términos, Campeche, México, after hurricanes
Authors: Bazúa Durán Carmen , Azamar Reyes Pamela A. , Au Whitlow W.
Published: November 2016

Laguna de Términos, Campeche, México, is one of the largest coastal lagoons in Mexico where snapping shrimp is the main source of biological sound. We measured the environmental noise from 2004 to 2008 in stations distributed homogeneously in this lagoon during 17 sampling periods using a digital audio tape recorder sampling at 48 kHz with 16 bits for 1 minute at each station. The environmental noise in the recordings was measured with a semi-automatic MATLAB routine designed for this purpose. Results indicate that environmental noise in the lagoon changes from one sampling to another, but it changed drastically after the hurricanes of 2005 in some of the stations. This changes in submarine environmental noise helps us in understanding the effects of natural phenomena in the distribution and abundance of marine wildlife, such as snapping shrimps and bottlenose dolphins. [Work supported by CONACyT-Campeche and PAPIIT&PASPA-UNAM.]
Acoustic characterization of the new Arctic during Ice Exercise 2016
Authors: Joseph John E. , Reeder D. B. , Nelson Mitchell S.
Published: November 2016

The Naval Postgraduate School (NPS) participated in Ice Exercise 2016 (ICEX-16), a multi-national naval exercise conducted in the Beaufort Sea during March 2016. Operating at a remote ice camp, NPS deployed several conductivity, temperature and depth (CTD) sensors to capture oceanographic variability to 500 m depth while performing a series of propagation tests. Mobile and dipped mid-frequency sources transmitted signals to a pair of vertical line array receivers positioned in the field to investigate depth, range, angular and specular characteristics of acoustic propagation and their correlation to variability in oceanographic structure and under-ice conditions. CTD data indicate there was significant variability in sound speed at 50m depth where cold, fresh mixed-layer water interfaces with contrasting warm, saline Pacific Summer Water (PSW) that lays immediately below it. The data also show a persistent and stable subsurface sound channel existed as a result of the PSW with peak temperature at 80 m situated above colder Pacific Winter Water (PWW), resulting in a sound channel axis near 140 m depth. Both features have important implications on sonar performance in the Arctic. Modeled and measured transmission loss are compared to quantify the effects.
Ultrasonic characterization of seagrass leaf blades (Posidonia oceanica)
Authors: Johnson Jay R. , Venegas Gabriel R. , Wilson Preston S. , Hermand Jean-Pierre , Urban Thibault
Published: November 2016

It has been shown that simple mixture theory models are inadequate to describe low-frequency sound propagation through seagrass meadows and further understanding of the acoustic properties of seagrass tissue is necessary. To that end, we present two ultrasonic sound speed measurements on the Mediterranean seagrass Posidonia oceanica. First, a transit time measurement through a stack of 120 leaf blades at 2.25 MHz are compared to similar measurements made on macroalgae Ecklonia radiata. Sound speed differences are related to the gas content within the aerenchyma of seagrass and other tissue characteristics. Second, ultrasonic sound speed measurements through a suspension of finely divided P. oceanica leaf blades at frequencies between 1 and 4 MHz are compared to low-frequency (1-8 kHz) sound speed obtained on the same blade suspension by means of a resonance chamber.
Determination of acoustic waveguide invariant using ships as sources of opportunity in a shallow water marine environment
Authors: Verlinden Christopher M. , Sarkar Jit , Cornuelle Bruce , Kuperman William A.
Published: November 2016

The waveguide invariant (WGI) is a property that can be used to localize acoustic radiators and extract information about the environment. Here, the WGI is determined using ships as sources of opportunity, tracked using the Automatic Identification System (AIS). Using a single hydrophone the acoustic intensity as a function of range and angle is measured in the presence of ships at a variety of ranges and angles. The relationship between range, intensity, and frequency is used to determine the WGI parameter β for ships in a variety of positions. These Beta values are interpolated and a map of β is created for the environment in question. The method is demonstrated using data collected on a single hydrophone in a shallow water environment off the coast of Southern California.
Tissue lesion formation induced by high intensity focused ultrasound along a spiral pathway
Authors: Zhang Dong , Tu Juan , Guo Xiasheng , Ma Qingyu , Guo Gepu
Published: November 2016

Both theoretical and experimental studies were performed here to investigate the lesion formation induced by high-intensity focused ultrasound (HIFU) operating in continuous scanning mode along a spiral pathway. The Khokhlov-Zabolotskaya-Kuznetsov equation and bio-heat equation were combined in the current model to predict HIFU-induced temperature distribution and lesion formation. The shape of lesion and treatment efficiency were assessed for a given scanning speed at two different grid spacing (3 mm and 4 mm) in both the gel phantom and ex vivo studies. The results show that uniform lesions can be generated by the homogenization of thermal diffusion along the spiral scanning pathway. The complete coverage of the entire treated volume can be achieved as long as the spacing grid of the spiral pathway is smaller than a critical value that right matches the maximum thermal diffusion dimension, and the treatment efficiency can be optimized by selecting an appropriate scanning speed. This study can provide guidance for further optimization of the treatment efficiency of HIFU therapy.
Relative impedance variation based temperature monitoring and dose control for high intensity focused ultrasound therapy
Authors: Ma Qingyu , Guo Gepu , Tu Juan , Zhang Dong , Feng Shaotong
Published: November 2016

High intensity focused ultrasound (HIFU) can be used as a non-invasive and efficient therapy approach to treat tumors by heat coagulation with less metastasis, although it is still limited by inaccurate temperature monitoring and efficacy evaluation. Based on the relationship between temperature and electrical impedance, a model of impedance measurement during HIFU therapy was established. Numerical studies on the distributions of acoustic pressure, temperature and conductivity were simulated, and the impedances in the model were calculated with the electrical potential and current density. It is proved that, for a fixed acoustic power in the focal region, the relative impedance variation (RIV) linearly increases with the increasing treatment time and is inversely proportional to acoustic power, while the relative impedance variation rate (RIVR) shows a linear relationship with the acoustic power. The treatment time that is required for the temperature in the focal region to reach 70 degree is inversely proportional to the square of acoustic power. The experimental results of RIV and RIVR measured at different powers and treatment times are in good agreements with the simulated data. The results suggest that the RIV can be used as a useful indicator for the non-invasive temperature monitoring and efficacy evaluation, and might provide new strategy for accurate dose control of HIFU therapy.
Parametric array for tissue harmonic imaging
Authors: Keravnou Christina P. , Averkiou Michalakis A.
Published: November 2016

More than 50% of abdominal scans are performed on technically difficult patients due to worldwide increase of obesity. Tissue harmonic imaging has shown some improvements on obese patients but the problem remains unsolved. The use of dual frequency pulses allows the generation of sum and difference frequencies in tissue. We hypothesize that the difference frequency (Δf, parametric array) can survive larger penetration depths and increase SNR while maintaining the spatial characteristics of the primary wave. Our objective was to optimize the parameters for efficient generation of the parametric array and study its spatial characteristics for imaging obese patients. Numerical simulations using KZK equation and measurements in tissue-like media were performed to study parametric arrays. Pulses with two frequencies (f1, f2) were considered where 0.1f1≤Δf≤f1. Pulse inversion was utilized to isolate even harmonics, including Δf. The amplitude of Δf was maximized at Δf = f1. The axial resolution is not seriously compromised by the lower frequency of Δf when using PI. For 0.5 dB/cm attenuation difference between Δf and 2f1, Δf echoes from 20 cm deep were greater by 10 dB. Application of the parametric array on larger technically difficult patients would offer similar benefits as those in sonar applications.
Controlled nanoparticle release through microbubble microstreaming: Physical insight and applications
Authors: Lajoinie Guillaume , Luan Ying , Gelderblom Erik C. , Dollet Benjamin , Dewitte Heleen , Lentacker Ine , Versluis Michel
Published: November 2016

Microbubbles driven by ultrasound are used in a number of applications including surface cleaning, ultrasound imaging, and as a vehicle for local drug delivery. To prolong the microbubble lifetime, its gas core is coated with a stabilizing shell, typically consisting of phospholipids. The coating can also be used to attach a payload of functional nanoparticles. Interestingly, upon ultrasound irradiation at several hundreds of kPa, the payload was observed to be released in a highly controlled way. This release carries great potential for using microbubbles as drug delivery agents in the context of personalized medical therapy. However, until now, limited experimental observations of the phenomenon are available. Here, we study using ultra high-speed and fluorescence imaging techniques in top and in side-view the underlying mechanisms of the release. We also developed a model on the basis of a Rayleigh-Plesset-type equation that reveals that non-spherical bubble behavior is key to the release mechanism. We also quantified the streamlines and acoustic streaming velocity responsible for the microfluidic transport of the material and propose for the first time a complete physical description of the controlled release of ultrasound actuated microbubbles.
Detection of tumoral netrin-1 protein levels using ultrasound microbubble contrast agents:
In vitro
validation
Authors: Wischhusen Jennifer , Delcros Jean-Guy , Mehlen Patrick , Padilla Frederic
Published: November 2016

Netrin-1 is a protein secreted by tumor cells in breast cancers. It triggers survival and proliferation through its interaction with the dependence receptor UNC5B. Netrin-1 is the target for a therapy under development. To identify patients who can benefit from treatment, a companion diagnostic is required. Our aim is to characterize netrin-1 as a target for ultrasound molecular imaging and to validate netrin-1-targeted microbubbles. Netrin-1 interactions with the extracellular matrix were analyzed by flow cytometry and Western blot. Microbubbles were functionalized and binding under static and dynamic conditions on purified netrin-1 or netrin-1-expressing cells was assessed by light microscopy. Netrin-1 interacted with heparin sulfate proteoglycans on the surface of the cells and with the cell surface receptor UNC5B. Microbubbles specifically and dose-dependently bound to netrin-1 protein and netrin-1-expressing cells, in absence and presence of UNC5B. Our findings confirmed that netrin-1, although being a secreted protein, is a potential target for ultrasound molecular imaging using microbubbles that specifically attach to netrin-1 presented on the cell surface. Currently, netrin-1 presentation on the luminal side of the vascular endothelium and ultrasound molecular imaging in the living animal are assessed.
Micro ultrasound motor with coiled stator for rotationally driving of ultrasound beam of Intravascular ultrasound imaging system
Authors: Takeuchi Shinichi , Kurita Keisuke , Uehara Chouyuu , Ozeki Seiya
Published: November 2016

For the purpose of performing radial scanning by rotating ultrasound beam in intravascular ultrasound imaging system for diagnosing the state of thrombus and stenosis in a blood vessel such as the coronary arteries of the heart, we are developing micro Coiled Stator UltraSound Motor (CS-USM). Three types of coiled stators with materials of titanium, stainless steel or copper were prepared. These coiled stators were 5 wound acoustic waveguide with 0.5 mm width and 0.1 mm thickness. Size of coiled stator is 0.9 mm diameter and 3 mm length. PZT ceramic vibrator or hydrothermal PZT film vibrator was employed. When two vibrators-type inner rotor CS-USM having stainless steel coiled stator were driven by voltage of 30Vpp at 311 kHz, rotational speed was 3500 rpm, torque was 0.34μNm. Maximum rotational speed of one vibrator-type inner rotor CS-USM having hydrothermal PZT film was 1100 rpm. Maximum rotational speed of one vibrator-type inner rotor CS-USM with titanium or stainless steel coiled stator was 2400 rpm. Rotational speed of the one vibrator-type inner rotor CS-USM with copper coiled stator driven by same conditions was 3200rpm. Maximum rotational speed of two vibrator-type outer rotor CS-USM with stainless steel coiled stator and PZT ceramic vibrators was 1400 rpm.
Discrepancies in the reproduction of the spectral characteristics of the acoustic stethoscopes by the electronic stethoscopes and potential diagnostic consequences
Authors: Nowak Karolina M. , Nowak Lukasz J.
Published: November 2016

The electronic stethoscopes implement selectable low- and high-pass digital filters in order to mimic the declared acoustic characteristics of the bell and diaphragm chest pieces of the acoustic stethoscopes. However, the question arises if such a simple approach can exactly reproduce the actual, complex spectral characteristics of the acoustic stethoscopes, which are strongly affected by the acoustic coupling between the body of a patient and the chest piece? The present study introduces the results of the relevant experimental investigations. The acoustic characteristics of four different electronic stethoscopes operating in bell and diaphragm modes were determined during the heart auscultation examinations combined with the synchronized ECG recordings. The heart sounds were recorded using a microphone placed in one of the earpieces, while the ECG signals were used to extract interference-free fragments corresponding to single heartbeats. The averaged spectra of a large numbers of such fragments were used to determine the acoustic parameters of the investigated devices. The obtained results are compared to the corresponding results obtained for the acoustic stethoscopes, showing significant discrepancies. The potential diagnostic consequences of such discrepancies are discussed based on the available auscultation guidelines for physicians, which do not take into account the described effects.
Study on measurement technique for acoustic cavitation using cavitation bubble signals
Authors: Uchida Takeyoshi , Yoshioka Masahiro , Matsuda Youichi , Horiuchi Ryuzo
Published: November 2016

Acoustic cavitation shows an excellent effect on ultrasonic cleaning and it also has prospects of application to cancer treatment. However, further study is essential to solve the problems such as low yield ratio and safety for human body because too much cavitation can damage the target. In this respect, quantitative evaluation of the generated cavitation is required. The mechanical index has been used so far but it does not reflect the quantity of the generated cavitation. Thus, we have been studying a new measurement technique by using the signal generated from cavitation bubbles, frequency spectrum of which is composed of broadband noise and subharmonics. We have reported that broadband noise has potential as an index for the amount of the generated cavitation. In this presentation, we experimentally investigated the level change of both broadband noise and subharmonics by increasing the acoustic pressure. We found that these two components are observed at the different level of acoustic pressures, probably corresponding to the different kinetic state of the cavitation bubbles.
Focused ultrasound therapy of cervical lymph nodes in rats for alleviating multiple sclerosis symptoms
Authors: Podkowa Anthony , Miller Rita J. , Motl Robert W. , Oelze Michael L.
Published: November 2016

Multiple sclerosis (MS) is a prevalent neurological disease among adults worldwide. Disease modifying therapies are only modestly effective for slowing long-term progression of pathological and disability outcomes. One approach to treating MS is to reduce the burden of lymphocytes entering the central nervous system. We hypothesized that using focused ultrasound (FUS) to heat the cervical lymph nodes in rats with EAE, an animal model of MS, would alleviate symptoms of EAE by reducing lymphocyte burden. EAE was induced in rats through injection of myelin oligodendrocyte glycoprotein (MOG) and EAE disability scores were recorded over 21 days post injection. The cervical lymph nodes of rats with EAE were treated at day 9 and day 12 post MOG injection using FUS to elevate the temperature to 43-44 °C for 20 minutes. On average the EAE remittance score for FUS treated rats was 1.14 ± 0.48 versus 0.33 ± 0.27 for sham treated rats. These differences were statistically significant (p = 0.037). Remittance of the EAE disability scores were highly correlated with the last therapy application. Therefore, FUS treatment of cervical lymph nodes in rats with EAE resulted in a significant reduction in EAE score, which was not observed in sham treated rats.
Fast measurement of the temperature distribution in a blast furnace using impulse response measurement
Authors: Behler Gottfried , Richter Jan-Gerrit , Buzga Sebastian
Published: November 2016

The temperature profile on top of a blast furnace gives meaningful information about the heat distribution and the activity of the ballast below. Since a direct measurement using temperature probes is both complicated due to the filling procedures and expensive due to the repeated damage of the sensors. An indirect measurement of the temperature is given by the measurement of the propagation delay for sound which by a known distance reveals the average temperature of the gas in between source and receiver position. The temperature distribution is then derived by a tomographic approach in one plain above the blast furnace with different source and receiver positions. Basically, this method is not new and it is used with stochastic (pneumatic excitation) signals in many applications. The typical measurement time for a single temperature profile takes about 20-30 seconds. It is obvious that the temperature distribution will not be stable for such a long time; hence, the measurement results are not very much reliable. The background noise in the blast furnace and the excitation signal are of the same type (noise), hence the correlation of the measured signal very often fails. In this paper, a new electroacoustic method using interleaved swept sine excitation will be described.
A broadband acoustic absorber based on phase-modulating reflective metasurfaces
Authors: Wang Wenqi , Li Junfei , Popa Bogdan-Ioan , Cummer Steven
Published: November 2016

Most high performance acoustic absorbers exhibit outstanding absorption capabilities at resonant frequencies, thus their bandwidth are significantly limited. Acoustic metasurfaces enabled unprecedented wave manipulation with their planar profiles, subwavelength thicknesses, and large degree of design freedom. However, studies have been primarily focused on extraordinary wavefront shaping functionalities, and little explorations has been made on manipulating transmitted/reflected power of diffracted beams. By carefully tailoring the design and arrangement of acoustic metamaterial cells, enhanced absorption can be achieved for a broad range of frequencies. Building on our previous works on transmissive and reflective metasurfaces with exotic properties, including anomalous refraction, surface mode conversion, and extraordinary beam-steering (Xie et al. Nat. Commun. 2014), we present in this work a broadband acoustic absorber built with an expanded library of labyrinthine acoustic metamaterials. We demonstrate that by engineering the phase modulation profile of phase-modulating metasurfaces, incident waves can be effectively converted to surface modes that propagate along the air-metasurface interface, thus minimal reflection is observed in the far field. Our work extends functionalities of acoustic metasurfaces, demonstrates an alternative route to the design of broadband acoustic absorbers, and can be potentially applicable to noise control.
High performance and robust audio search
Authors: Wang Avery
Published: November 2016

In this talk, I will give an overview of the Shazam audio recognition technology. The Shazam service takes a query comprised of a short sample of ambient audio (as little as 2 seconds) from a microphone and searches a massive database of recordings comprising up to 40 million songs. The query audio may be distorted with significant additive noise (<0 dB SNR), environmental acoustics, as well as nonlinear distortions. The computational scaling is such that a query may cost as little as a millisecond of processing time. Previous algorithms could index hundreds of items, required seconds of processing time, and were less tolerant to noise and distortion by 20-30 dB SNR. In aggregate, the Shazam algorithm represented a leap of more than 1E + 9 in efficiency. I will discuss the various innovations leading to this result.
The promises and realities of machine learning
Authors: Valente Dan
Published: November 2016

These days, anyone with a laptop, Python, and a free afternoon can build an intelligent machine. In fact, if you have a bunch of data, go ahead and throw it into a deep neural net: your worries will be over! Machine learning will save us all! Unfortunately, those of us who spend our days fighting with these systems know that this is far from the truth. As anything created by humans, these algorithms have limitations, and there is no algorithmic substitute for careful thought. The gory details of techniques like Support Vector Machines, Neural Networks, and K-means clustering can be found in innumerable blog posts, texts, and online courses; we won’t discuss the details here. Instead, this talk will focus on the conceptual and mathematical framework under which all machine learning algorithms fall. We’ll briefly discuss the workings of a few of the most popular modern techniques (#DeepLearning, anyone?) and how they fit into this framework. More importantly, we’ll discuss some often-overlooked considerations that go into the design of these systems: human biases, transparency, and maintainability. Ultimately, we hope to provide a solid understanding of what these algorithms can do, what they can’t do, and when they should or should not be used.