bluuebunny/crossref_metadata_2025 huggingface dataset:
Perception of word boundaries in spontaneous speech
Authors: Tao Jiaer , Torreira Francisco , Clayards Meghan
Published: October 2018

Studies of lab speech have identified several acoustic variables that listeners use to identify word boundaries (e.g. allophonic variation, segment duration), however spontaneous speech may not contain the same acoustic signals. Using data from a recent study we tested whether disambiguating information is also available to listeners under more typical conditions. 15 pairs of target phrases only differing in the placement of word boundaries, e.g., grey#day vs. grade#A were elicited under read (146 tokens) and spontaneous speech conditions (316 tokens) from multiple talkers who were not aware of the ambiguities. Phrases were played in isolation to 30 Native English listeners in a 2AFC segmentation task (e.g. grey day vs. grade A). Accuracy was above chance for both read (80.9%) and spontaneous speech (73.1%). Accuracy varied according to the critical consonant type and was highest for voiceless stops followed by nasals, voiced stops, fricatives and clusters. Only two items (pierced ears vs. peer steers and beef eater vs. bee feeder) were at chance for spontaneous speech. Measures of word-initial lengthening were good predictors of performance but listeners outperformed predictions from these measures indicating they weren’t the only cues.
The role of distributional information in cross-talker generalization of phonetic category retuning
Authors: Tzeng Christina , Nygaard Lynne C.
Published: October 2018

Listeners use lexical information to retune phoneme categories. Previous findings on the specificity of such perceptual adjustments suggest that cross-talker generalization occurs when talkers are acoustically similar. An alternative mechanism implies that listeners are sensitive to the statistical distribution of phonetic variation across speakers and can use this sensitivity to track both group- and talker-specific phoneme boundaries. Our objective is to disambiguate between these two possibilities. In the experiment, listeners hear words with an ambiguous fricative produced by multiple speakers of American English. Utterances across talkers vary in two ways: 1) the similarity of particular talkers’ categorization curves and 2) the statistical distribution of sounds along the phonetic continuum (e.g., unimodal vs. bimodal) across talkers. We assess phonetic category retuning using novel words by novel talkers whose utterances either match or mismatch talker-specific properties or the distribution of phonetic realizations heard during exposure. If cross-talker generalization is similarity-based, listeners should generalize retuned phonetic representations to specific similar-sounding talkers at test. Alternatively, if listeners capitalize on the statistical distribution of exposure sounds, listeners should generalize to test talkers whose productions are consistent with the learned distribution. Results inform the conditions under which listeners form talker-independent representations of speech sound categories.
Perceptual asymmetries in lexical tone perception
Authors: Wayland Ratree , Chen Si
Published: October 2018

Perceptual asymmetric relations between two stimuli such as perceptual confusions where stimulus A is more frequently confused as stimulus B than the reverse has previously been accounted for in terms of response bias due to the prevalent assumption that perceptual space is Euclidean (Polka & Bohn, 2003). Perceptual asymmetries in lexical perception have been reported for both infants and adults. Tsao (2008) found that a stimulus change from the background mandarin T1 (55) to the target Mandarin T3 (213) was easier than the reverse among one-year-old Mandarin learning infants. Politzer-Ahles et al. (2016) found that mismatch negativity (MMN) was attenuated among both native and non-native Mandarin listeners when Mandarin T3 was the standard and another deviant in comparison to the reverse. This study examines the effects of memory load and first language (L1 background) on perceptual asymmetry patterns in adult lexical tone perception. All possible pairings in both orders of Mandarin tones produced on two open syllables [ma] and [ni] will be presented to native Mandarin and American English listeners in an AX categorial discrimination task. To examine the effects of auditory memory load, two different inter-stimulus-interval (ISI), 250 ms and 1,000 ms, will be used.
Non-native production of Mandarin T2/T3 pairs in disyllabic real and pseudo words
Authors: Wu Xianghua
Published: October 2018

Mandarin rising (T2) and falling rising (T3) tones have been found to be the most confusing tone pair for native and non-native production due to similar F0 trajectory and equivalent lexical function known as T3 sandhi. This ongoing preliminary study investigates non-native production of T2 and T3 combinations in disyllabic real and pseudo words, aiming to examine whether T3 sandhi is realized solely at the real word level. Another goal of this study is to explore the effects of two distinctive orthographic systems in Mandarin (i.e., the sound-based pinyin and the meaning-based Chinese characters) on tone production. Ten native English speakers with 8-12 months experience in learning Mandarin participated in the production task. The stimuli were combinations of T2-T2, T2-T3, T3-T3, and T3-T2 grouped into four semantic and orthographic contexts: real and pseudo words in pinyin only, and those in both pinyin and Chinese characters. In the perception task, five native listeners of Mandarin identified the tone category for the first and second syllables. The results are expected to indicate the effects of tonal context, word meaning, and/or orthographic input on T2/T3 productions, and will be compared with earlier findings (e.g., Mok et al., 2018; Zhang et al., 2015).
Detecting infrasound signals and sources with dense network data
Authors: Hedlin Michael A. , de Groot-Hedlin Catherine
Published: October 2018

New, massive, datasets can be used to examine atmospheric phenomena in more detail than before but require analytical methods that are both efficient and capable of extracting useful information from faint signals immersed in noise. We have developed the AELUMA (Automated Event Location Using a Mesh of Arrays) method that recasts any dense network of sensors as a distributed mesh of triangular arrays. Each array provides a local estimate of signal properties. This information from arrays across the network is combined to estimate the source origin time and location. The process is repeated without oversight to catalog events. A key challenge in attributing signals to their source occurs when a large number of signals are detected nearly concurrently from different sources. We apply a cluster (decision tree) analysis that takes the results of array processing at all arrays to iteratively parse out subsets of detections from distinct sources. We used recordings of infrasound signals made at an extensive network of sensors to build a catalog of infrasonic activity across the continental United States. The accuracy of AELUMA is assessed using events for which the origin time and location are well known.
Acoustic seafloor classification using machine learning and simulations of Helmholtz equations
Authors: Frederick Christina , Michalopoulou Zoi-Heleni
Published: October 2018

We discuss numerical methods for inverse problems in high frequency underwater acoustics, aiming to recover detailed characteristics of the seafloor from measured backscatter data generated from SONAR systems. The key to successful inversion is the use of accurate forward modeling capturing the dependence of backscatter on seafloor properties, such as sediment type, roughness, and thickness. Prediction models are often statistical models formed using years of collected ground-truth data or physical models that require costly simulations or unrealistic environmental assumptions. Sophisticated tools are needed to accommodate complicated scenarios, i.e., uncharted seafloor landscapes. To enable a rapid, remote, and accurate seafloor parameter recovery, we propose a combination of machine learning and high fidelity forward modeling and simulation of the physical wave propagation and scattering process. The idea is to partition environments on the order of kilometers in width into much smaller “template” domains, a few meters in width, where the sediment layer can be described using a few parameters. Machine learning is used to train a classifier using a reference library of simulations of Helmholtz equations on the domains. We investigate the potential of multilayer perceptrons and generalized regression in sediment identification using the reference library. [Work supported by NSF and ONR.]
Big data based ocean acoustic source localization via deep learning
Authors: Niu Haiqiang , Gong ZaiXiao , Wang Haibin , Reeves Ozanich Emma , Gerstoft Peter
Published: October 2018

Machine learning has shown its potential in ocean acoustic source localization when real data are available to construct the training data set (Niu et al., JASA 142, 1176–1188 (2017); Niu et al., JASA 142, EL455–460 (2017)). This paper investigates the cases suffering from deficient real observations, where big data generated from the acoustic propagation model are used as the training set and therefore deep learning models could be exploited. To handle the environmental uncertainty, the multi-frequency acoustic data are generated using an acoustic propagation model (KRAKEN) based on tens of thousands of environments. A 50-layer residual neural network model (ResNet-50) is used to address this challenging problem. The performance on simulated and experimental data demonstrates that the proposed approach is able to adapt to a variety of environments in source localization problems.
Curvature and distance amplitude correction for ultrasonic testing of a component with curved surface using deep learning method
Authors: Mei Yujian , Jin Haoran , Yu Bei , Wu Eryong , Yang Keji
Published: October 2018

Surface curvature and distances from the transducer will have an effect on the amplitude of ultrasonic wave. When using the amplitude of ultrasonic signal to quantitatively size the flaws, a correction is necessary to assure all ultrasonic signal amplitude is based on the echo signal from flat surface. Hence, a deep learning method is proposed to adjust the signal amplitude which enters arbitrary curved surface. A deep learning model will adjust the signal amplitude as the radius of surface, distance from the transducer and attenuation coefficient of material. Then, the ultrasonic signal is imaged on the basis of corrected ultrasonic data. Compared to the ultrasonic imaging based on the raw data, the quantitative evaluation of flaw size is more precise by using the deep learning method. The deep learning model is trained by the CIVA simulation data. Ultimately, the model is verified by the comparisons between prediction and experimental data. The proposed method is adaptable to various curvature, distance, and material, which avoids manufacturing multiple standard specimens to satisfy lower costs and shorter cycle.
Green’s function emergence through cross-correlation of shipping noise
Authors: Skarsoulis Emmanuel , Cornuelle Bruce
Published: October 2018

The cross-correlation of the underwater acoustic noise field at two locations is related to the time-domain Green’s function (TDGF) between the two locations. The propagation conditions, the distribution of noise sources, and the hydrophone locations have a significant influence on the part of the TDGF that can be reliably reconstructed through the cross-correlation procedure. In the low-frequency part of the acoustic spectrum the dominating noise source is shipping, and for that case the effect of propagation conditions on the result of the cross-correlation procedure is studied by considering typical sound velocity profiles and hydrophone setups. The aim is to understand the effect that propagation conditions have on the cross-correlation procedure and point to the potential advantages of certain areas for the conduct of passive tomography experiments. Further, the effect of mooring motion on the cross-correlation result is addressed and ways to remove this effect, e.g., with the help of long-baseline navigation systems will be discussed. [Work supported by ONR.]
Soundscape measurements and modeling of the Atlantic Outer Continental Shelf
Authors: Murray James J. , Heaney Kevin D. , Campbell Richard L.
Published: October 2018

The impact of anthropogenic sound on the marine ecosystem has become an area of concern and subsequently increased research. As part of the Atlantic Deep Water Ecosystem Observatory Network (ADEON, adeon.unh.edu), a five-year collection effort of acoustic, oceanographic, marine ecosystem, and remote sensing satellite observations is underway. The centerpiece of the network is 6 long-term landers deployed off the coast of Jacksonville up past the mouth of the Chesapeake Bay. In this paper we present results from the first (of four) horizontal line array measurement cruises (deployed from a sailboat) between two of the moorings. The scientific objective is to evaluate the horizontal directionality of the ambient sound field and to measure the spatial correlation of the noise between the lander off of Wilmington NC and the lander off of the Virginia. A soundscape model, including environmental and source level variability will be presented. The acoustic sources will include ships, wind, rain, and marine mammals.
Spatio-temporal modelling of underwater noise related to an arctic exploration drilling program
Authors: Quijano Jorge E. , Hannay David E. , Austin Melanie
Published: October 2018

One concern related to oil and gas industry activities in the arctic is the potential impact of anthropogenic noise on marine mammals. To gain understanding of the temporal evolution of the acoustic noise footprint from such activities, and to quantify the geographic extent at which sound levels remain within regulatory thresholds for marine mammal injury and behavioral disturbance, this work presents a comprehensive monitoring and modeling study of anthropogenic noise resulting from an exploration drilling project in the northeastern Chukchi Sea, conducted from July to October, 2015. Measured acoustic source levels of multiple vessels and drilling equipment were used to generate time-dependent wide-area noise fields. Model validation was carried out by comparing simulated results with high-resolution acoustic data acquired at multiple stations in the area. The study shows that noise radiating from up to 19 supporting vessels is usually dominant, but noise from certain drilling-related activities occasionally rises above vessel noise within a radius of 8 km from drillsites. Modeled scenarios also show that by constraining vessel positions to within a few kilometers of the drilling location, simultaneous construction of two oil well top holes results in minor increment of the aggregate acoustic footprint’s extent relative to single-well drilling.
The preliminary study on fluctuation of ocean sound field
Authors: Weng Jin-bao , Yang Yan-ming
Published: October 2018

The ocean environmental variation causes the amplitude and phase fluctuations of acoustic signals that travel in the ocean acoustic waveguide. Sound propagation fluctuation is studied based on the deep water fixed-point sound propagation experiment data acquired in the northern South China Sea in 2016. In this experiment, two sets of submerged buoy systems, which integrate the emission and receiving of sound wave, have continuously and steadily worked as long as three months. Considering the Doppler frequency shift, the amplitude and phase of acoustic signals are calculated after matched filtering. The sound intensity scintillation index computed for the entire record is 0.8, which is less than the saturation value of one. In contrast, the scintillation index computed for the 2001 ASIAEX South China Sea Experiment is 2.6 and 1.7. The ocean environmental variation and its relation with sound propagation fluctuation are analyzed.
Variability of target echo and clutter in the 2013 Target and Reverberation Experiment
Authors: Ellis Dale D. , Yang Jie , Hefner Brian T. , Tang Dajun
Published: October 2018

The Target and Reverberation Experiment was conducted in the Gulf of Mexico, off Panama City, Florida. Reverberation, noise, and target echo measurements were carried out for more than a month during April and May 2013, using a fixed source and fixed horizontal array receiver deployed in about 20 m of water. To support modeling efforts, a considerable number of ancillary environmental and transmission loss measurements were made. Various pulses in the 1.8–3.6 kHz frequency band were transmitted day and night, and have produced a rich data set. Initial results by various authors were published in the recent TREX13 Special Issue of the IEEE Journal of Oceanic Engineering. This work extends the analysis, concentrating on the variability of the echoes from various targets: a vertical hose, vertical arrays, a towed echo repeater, the hull of the towing ship, and other persistent bottom scatters, such as shipwrecks. In addition to the ping-to-ping variability of the echoes there are consistent trends, which are not understood, though probably due to oceanographic effects. An attempt will be made to relate the echo variability to measured and modeled reverberation and transmission loss. [Work supported by ONR, Ocean Acoustics, Code 22.]
Characterizing acoustic propagation within the approach channel to Brandon Road Lock and Dam
Authors: Denes Samuel L. , Zeddies David , Woodley Christa
Published: October 2018

A propagation experiment was conducted in the approach channel to the Brandon Road Lock and Dam on the Des Plaines River in Joliet, Illinois, over the course of ten days in 2017. A sequence of frequency sweeps, continuous tones, and white noise was broadcast from an underwater transducer deployed from a shallow draft workboat at nine locations within the channel. A vertical array of one tri-axial particle motion sensor and three hydrophones was deployed from a movable platform and recorded signals throughout the approach channel. An additional bottom mounted, autonomous recorder with one hydrophone and one particle motion sensor was deployed outside of the navigable channel for the duration of the experiment. The engineered channel includes cement walls and floors near the steel lock doors, transitioning to natural surface shoreline down channel. For sources or receivers near the lock, the highly reverberant interfaces dominate propagation effects. This presentation will compare results of the measurement experiment with propagation models.
Measured variability of acoustic propagation loss in the Salish Sea, British Columbia, Canada
Authors: O'Neill Caitlin , Yurk Harald , Vagle Svein
Published: October 2018

The Salish Sea encompasses the waters between southern British Columbia mainland coast, Vancouver Island, and Washington State. Its waters are used by commercial and recreational fishers, host shipping traffic to the major ports of Vancouver and Seattle, and is travelled frequently by local ferries. It is also an important habitat for many marine mammal species, including the endangered Southern Resident Killer Whale (Orcinus orca). Southern Resident Killer Whales use calls, whistles, and clicks to communicate and find prey. Human activities on the water may affect the marine acoustic environment by masking whale vocalizations, which in turn will negatively impact the ability of the whales to forage and socialize. A field study was conducted to measure acoustic transmission loss at various places in the Salish Sea. Sound signals simulating killer whale call elements were broadcast from different angles to a calibrated hydrophone. Results from the study showed that acoustic transmission loss is highly spatially variable in this area. We suggest that these observations are due to changes in oceanography conditions and ambient sound levels, which are important factors to consider when assessing impact on Southern Resident Killer Whales. [Work supported by the Oceans Protection Plan of the Government of Canada.]
Confined space acoustic studies in Weymouth Fore River
Authors: Duda Timothy F. , Newhall Arthur , Traykovski Peter , Porter Michael B. , Henderson Laurel
Published: October 2018

An acoustic propagation study with two moving sources and three receiver positions was conducted in May 2018 in Weymouth Fore River, Massachusetts. Detailed bathymetric and geometric boundary information was previously collected. The data show strong inter-ping variability at ping rates of four Hz and one Hz. Signals were linear sweeps from 8-16 kHz and 21-34 kHz. The variation of the matched-filter envelope output, thought to be robust to phase alterations from small movements, was highly variable. This implies interfering multipath surpassing slowly varying response to boundary-interaction changes for the slowly varying source. The signatures of boundary interaction in models are compared to data to evaluate modeling procedures in the BELLHOP3D program. Interactions with concrete boundaries and steel ship and barge hulls are included in the analysis.
A full-field time-domain model for reverberation in complex environments and waveguides with rough interfaces
Authors: Ivakin Anatoliy
Published: October 2018

A full-field perturbation approach [Ivakin 2016] has been used for modeling reverberation at given frequency in spatially varying layered environments and waveguides with rough interfaces. Average reverberation intensity was shown to be related with a local Bragg-wavenumber power spectrum of roughness through integration over the reference (unperturbed or smoothed) interfaces. The integrand includes a factor, a two-way propagation/interaction kernel, defined in terms of Green’s function and a local contrast of acoustic parameters at the interfaces. This work extends the approach to time domain and includes additional integration over frequencies with another factor in the integrand, the radiated energy time-frequency distribution (ambiguity function). However, the integration within the signal frequency bandwidth can be significantly simplified using the frequency-range interference invariant. As a result, extremely fast estimations of reverberation time series (codas) can be made which require calculations of Green’s function of the reference medium in the vicinity of the interfaces at only one (central) frequency. Numerical examples for time dependence of narrow- and broad-band reverberation in layered environments and waveguides with rough interfaces using PE-approximation for Green’s function are presented. A possibility for remote monitoring of temporal and spatial variability of ocean interfaces based on propagation and reverberation measurements is discussed. [Work supported by ONR.]
A study of underwater propagation model performance in complex environments with inherent uncertainty
Authors: Langhirt Mark , Martinelli Sheri , Holland Charles W.
Published: October 2018

A number of computational models have been developed for purposes of modeling and simulation of acoustic wave propagation in underwater environments. Almost all of these models make approximations to the wave equation; furthermore, the method of implementation has a direct impact on the trade-off between accuracy and computational efficiency. Sonar technologies also vary greatly in range and frequency and one model is generally not suited for all applications; there are often subtle differences between them that can be highly dependent on the particulars of the environment. We investigate the performance of various models (ray tracing, level sets, normal modes, parabolic equation, and energy flux) using at-sea data from real world environments to assess their robustness of in the presence of the inherent uncertainty involved in reconstructing an underwater environment. In particular, we focus on the effect of perturbations in the sound speed profile. The sound speed profile, as a model input parameter, is subject to measurement error, as well as to undersampling of what, in many geographical areas of interest, is a complex spatial-temporal process. Ultimately, our objective is to establish some guidelines for practical use of the models in applications.
Perturbation approximations for bathymetrically controlled ocean acoustic mode coupling
Authors: DeCourcy Brendan J. , Duda Timothy F.
Published: October 2018

A perturbation approximation of mode coupling equations for acoustic propagation in a submarine canyon environment is presented. The vertical modes and mode coefficients are represented by nearly adiabatic dominant mode functions and correction terms that are sensitive to the horizontal gradient of the variable bathymetry. This approach allows for a more accurate representation of the bottom boundary condition, and eliminates computationally expensive implicit equations for the mode coefficients, replacing them with explicit equations for the nearly adiabatic contributions and the bathymetrically sensitive corrections. The presented method is applied to sloping bottom environments based on real bathymetric data to examine in detail the role of bottom variations in coupled mode propagation scenarios. [Work supported by the ONR.]
Extracting the intrinsic geo-acoustic parameters from the effective geo-acoustic parameters
Authors: Zeng Juan , Zhao Z. D. , Ma Li , Shang E. C.
Published: October 2018

So far, most of the geoacoustic (GA) parameters are inverted through model-based approaches. The inverted GA parameters are not the intrinsic ones but the so-called “effective” ones. The “effective” GA parameters are model and frequency dependent and will be distorted due to model-mismatching. The real physical meaning of the term “effective” has not been fully addressed yet. In this paper we proposed to interpret the term of “effective” based on the Brekhovskikh’s reflection principle, which reveals how the GA parameters influence the Green’s function through the only channel, i.e. the bottom reflective coefficient. Based upon this point, we discuss the relationship between the “effective” GA parameters and the intrinsic GA parameters. First of all, it is shown that the real essential physical parameters, the reflective parameters, P(f) and Q(f) can be extracted from the “effective” GA parameters. Finally, with the help of P(f) and Q(f) some of the intrinsic GA parameters, the frequency dependence of the seabed attenuation and seabed sound speed profile can be retrieved.
Comparison of velocity and attenuation measurements to the corrected effective density fluid model for gassy sediments
Authors: Wang Fei , Huang Yiwang
Published: October 2018

To validate the corrected effective density fluid model for gassy sediments, an acoustic experiment was undertaken to measure the velocity and attenuation over the frequency range of 8 and 120 kHz in an indoor water tank. The velocity and attenuation obtained by different estimation methods have good consistency respectively. Both of them have four distinct peaks and there is one-to-one correspondence between velocity peaks and attenuation peaks. Through numerical simulation of the acoustic characteristics attributed to the resonance of gas bubbles with different radii, the existence of small bubbles causes the velocity to decrease in the vicinity of resonance frequency of large bubbles. Five modified Gaussian functions are introduced to model the bubble size distribution inside the gassy sediment. A best bubble size distribution is obtained by inversion of the velocity and attenuation data simultaneously, and the predictions of the corrected model are broadly in good agreement with the measurements.
Sound system Déjà Vu all over again!—Revisiting past design approaches in an acoustically challenging multi-purpose space
Authors: Britton Deb , Goen Dustin
Published: October 2018

In the late 90s, we were tasked with designing a sound reinforcement system that would provide great speech intelligibility, in a highly reverberant space, without modifying any of the architectural finishes. The sound system had to support different types of events, held in different locations within the space, and with varying audience sizes. In 2015, we were asked to revisit the original loudspeaker design, and upgrade the sound system in that same space. Flash forward a few more years, and the entire building is getting a renovation—and we are once again designing a completely new sound system. This paper presents a case study of the upgrades, and describes the challenges, the lessons learned, and the changes in approach from the original upgrade through to the most recent design.
Effects for emphasis, enhancement, expression, and exaggeration
Authors: Case Alexander U.
Published: October 2018

Sound recordings built through multitrack production face a competitive soundscape. Signal processing strategies have evolved with the production goal of increasing the audibility of specific signal traits — making the subtle more apparent, the performance more compelling, the recorded art more successful.
Passive echo detection and discrimination in bottlenose dolphins
Authors: Coffinger Sean P. , Houser Dorian S. , Finneran James J. , Mulsow Jason
Published: October 2018

Echolocation in bottlenose dolphins (Tursiops truncatus) is an active process involving outgoing signal transmission and echo reception. Transmitted echolocation “clicks” interact with a target to produce echoes that contain representative information about the target. Echolocation allows dolphins to detect, discriminate, and identify complex targets using only their hearing. However, it is unclear whether dolphins capitalize on an internal representation of echolocation clicks for matched filter processing or whether the same information (and performance) can be obtained through passive echo reception (i.e., without a corresponding ensonifying click). Here, we investigate the passive echo discrimination ability of a bottlenose dolphin by embedding a target echo in a stream of distractor echoes with similar spectral and time-domain characteristics. Initial testing has demonstrated excellent echo-discrimination ability in the light of multiple distractor echoes of similar amplitude. Additional testing is underway with expanded distractor sets and echo-ordering complexity. The paradigm specifically investigates the plausibility of perceptual identification without the potential for matched filter processing. If representational identity is attainable via a passive process and not degraded relative to active echolocation, then the function of the echolocation click might not serve in matched filter processing, though it would remain important for ensonification and in determining target location.
Bottlenose dolphin (Tursiops truncatus) vocal modifications in response to spectrally pink background noise
Authors: Zapetis Maria , Mulsow Jason , Schlundt Carolyn E. , Finneran James J. , Lyn Heidi
Published: October 2018

The increase of oceanic shipping is a global predicament. The resulting proliferation of underwater noise levels is a serious concern for marine mammal welfare, as it has the potential to interfere with the communicative signals of bottlenose dolphins (Tursiops truncatus). The Lombard effect and other noise-induced vocal modifications may be employed to compensate for reduced signal-to-noise ratios. This study aimed to determine which vocal modifications dolphins use during experimentally controlled background noise conditions. Three dolphins (ages 30–52) participated in behavioral hearing tests using an adaptive up-down staircase, go/no-go procedure with 15 or 40 kHz tones. Tones decreased by 3 dB increments if a dolphin responded to the tone with a conditioned whistle, and increased by 3 dB if they did not. Dolphins performed this task during ambient noise (control) conditions, as well as three elevated bandpass noise (experimental) conditions: 0.6–5 kHz (115 dB re 1 μPa) and 0.6–10 kHz (115 and 125 dB re 1 μPa). The acoustic parameters of the dolphins’ response whistles and victory squeals, such as duration, frequency, amplitude, and response latency, were analyzed and compared between control and noise conditions. These data provide a complement to field studies of odontocete noise-induced vocal modifications in the wild.
Data-driven discovery of dynamics for control
Authors: Brunton Steven
Published: October 2018

The ability to discover physical laws and governing equations from data is one of humankind’s greatest intellectual achievements. A quantitative understanding of dynamic constraints and balances in nature has facilitated rapid development of knowledge and enabled advanced technology, including aircraft, combustion engines, satellites, and electrical power. There are many more critical data-driven problems, such as understanding cognition from neural recordings, inferring patterns in climate, determining stability of financial markets, predicting and suppressing the spread of disease, and controlling turbulence for greener transportation and energy. With abundant data and elusive laws, data-driven discovery of dynamics will continue to play an increasingly important role in these efforts. This work develops a general framework to discover the governing equations underlying a dynamical system simply from data measurements, leveraging advances in sparsity-promoting techniques and machine learning. The resulting models are parsimonious, balancing model complexity with descriptive ability while avoiding overfitting. The only assumption about the structure of the model is that there are only a few important terms that govern the dynamics, so that the equations are sparse in the space of possible functions. This perspective, combining dynamical systems with machine learning and sparse sensing, is explored with the overarching goal of real-time closed-loop feedback control of complex systems.
Machine learning applied to broadband sound propagation on the New England Shelf
Authors: Knobles David P. , Wilson Preston S. , Badiey Mohsen
Published: October 2018

Addressed is to what degree can variability of an ocean waveguide, such as that associated with the seabed, be inferred by estimating a mapping y = f(x,θ) for input/category pairs (x,y) and parameterization θ. Feedforward neural network algorithms are employed to learn the optimal parameterization θ approximating f. The mapping includes a chain of functions with hidden layers or functions not directly related to the input. Supervised learning is applied to broadband propagation in a shallow water environment called the New England Mudpatch whose acoustic characterization has been studied continuously since 2015. In 2017 about 400 MK-64 Signal Underwater Sound (SUS) and Combustive Sound Sources (CSS) were deployed in a 30 × 11 km2 area with horizontal variability of the seabed for the purpose of inferring the statistics of the seabed characterization from the observed statistics of the acoustic field. The goal is to connect θ to physical source and waveguide parameter values. [Work supported by ONR.]
Ocean acoustic range estimation in noisy environments using convolutional networks
Authors: Reeves Ozanich Emma , Gerstoft Peter , Purohit Akshaya , Niu Haiqiang
Published: October 2018

Machine learning has been able to accurately estimate ocean acoustic source range in real data using passive ship signals (Niu et al., JASA 142, 1176–1188 (2017); Niu et al., JASA 142, EL455–460 (2017)). In this paper, we train a convolution neural network (CNN) to learn range-dependent features directly from the multi-frequency complex pressure field. The CNN network uses 2D inputs to take advantage of spatial relationships between frequency and depth. KRAKEN is used to simulate pressure magnitude and phase received on a vertical array at multiple frequencies, ranges, and signal-to-noise ratios (SNR), generated by adding white Gaussian noise. We show that performance at low SNR can be improved by increasing the size of the training data. The CNN-LSTM (long short-term memory) network, which incorporates sequential learning, is compared to the CNN at varying SNR. The models are tested on real data from the SBCEx17 experiment.
Navigating noise when comparing satellite and acoustic remote sensing data
Authors: Wall Carrie C. , Karnauskas Kristopher , Joseph Maxwell B. , McGlinchy Joseph , Johnson Brian R.
Published: October 2018

Using a novel combination of NASA satellite products and acoustic remote sensing measurements, we aim to examine the link between the surface expression and vertical structure of ocean productivity and biomass in the California Current System. Water column sonar data collected by the National Marine Fisheries Service for fisheries management have been archived at the NOAA National Centers for Environmental Information. These data are used to evaluate the variability of the marine biogeography. To identify patterns of acoustic reflectance of marine organisms, the data must first be free of noise and seafloor acoustic returns. However, removing the variety of noise present has proved to be a challenge due to need for manual tuning, a resource prohibitive step, and the size and complexity of the acoustic data. Collaboration with the University of Colorado’s Earth Lab has led to the development of machine learning models to automatically remove noise from this large dataset. An analysis of the fully automated, semi-manual, and machine learning quality control processes will be presented. The cleaned acoustic data are then compared to the interannual variability of the distribution of surface chlorophyll concentration and temperature from satellite ocean color measurements.
Acoustic propagation in the complex sclera for understanding the biomechanical changes associated with myopia
Authors: Mamou Jonathan , Rohrbach Daniel , McFadden Sally A. , Hoang Quan V.
Published: October 2018

Myopia affects up to 2.3 billion people and, although minimal levels of myopia are considered a minor inconvenience, high myopia is associated with sight-threatening pathology in 70% of patients. The anatomic changes occurring in the posterior sclera play an important role in myopia progression. Therefore, we investigated the biomechanical properties of the sclera using a well-established myopia model in guinea pigs. We employed two ultrasound-based approaches to better understand and quantify the microstructural changes occurring in the posterior sclera associated with high-myopia development. The first approach applied quantitative-ultrasound (QUS) methods to intact ex-vivo eyeballs of myopic and control eyes using an 80-MHz ultrasound transducer. The second approach used a scanning-acoustic-microscopy (SAM) system operating at 250 MHz to form two dimensional maps of acoustic properties of thin sections of the sclera with 7-μm resolution. We tested the hypothesis that the QUS and SAM-based properties are altered in myopia and can provide new contrast mechanisms to quantify the progression and severity of the disease as well as determine where the posterior sclera is most affected. Ultimately these methods will provide novel knowledge about the microstructure of the myopic sclera that can improve monitoring and managing high-myopia patients.
Effect of acoustic impedance mismatch between skin and bone on transcranial ultrasound transmission
Authors: Gupta Shreyank , Haïat Guillaume , Laporte Catherine , Belanger Pierre
Published: October 2018

A major problem with transcranial Doppler (TCD) ultrasound is the poor transmission of ultrasound through the skull bone causing image quality degradation. The reasons for the poor image quality are (1) acoustic impedance mismatch along the wave propagation path and (2) bone frequency-dependent attenuation. Transmission loss due to acoustic impedance mismatch is typically ignored in the literature. Therefore, the objective of this paper is to study the effect of acoustic impedance mismatch on the transmitted energy as a function of frequency. To achieve this, the wave propagation was modelled analytically from the ultrasonic transducer into the brain. The model calculates frequency-dependent transmission coefficient for a given skin and bone thickness combination. The model incorporates both attenuation and acoustic impedance mismatch effects. The model was validated experimentally by comparing with measurements using a bone phantom plate mimicking the acoustic properties of the skull. The average error on the skin thickness between the model and the experiment was less than 6% for a constant bone thickness. Further analysis of the simulation suggests that an optimized excitation frequency can be chosen based on skin and bone thicknesses that would improve ultrasound transmission.
Ultrasonic evaluation of anisotropic structure of swine skull
Authors: Murashima Nagomi , Bustamante Diaz Leslie V. , Matsukawa Mami
Published: October 2018

For the ultrasound treatment in brain, such as high intensity focused ultrasound (HIFU), understanding of the complicated ultrasonic propagation in the skull bone is important, because of the anisotropic and heterogeneous character. In this study, we experimentally investigated the ultrasonic wave propagation in the skull sample, considering the anisotropic structure. A cylindrical bone sample was fabricated along the thickness direction of the right occipital bone of a swine (diameter: 11.5 mm, height: 3.0 mm). The ultrasound velocity in the MHz range was measured in the radial direction by rotating the sample (0 degree: sagittal-axis) and changing the measurement position. The structure of the sample was also evaluated by the X-ray micro CT. There are three orthogonal trabecular alignments in bone sample: main, intermediate-shafts (IS) and minor. In the outer layer of the skull, IS were mostly found along the frontal-axis. Ultrasound velocity became higher as the wave propagation direction approached to IS and values were in the range from 2110 to 2790 m/s. In the dipole, ultrasound velocity became higher as the wave propagation direction approached to main-axis and values were in the range from 2080 to 2600 m/s.
Simulation of ultrasound propagation through human skull: Experimental validation and application to treatment planning
Authors: Padilla Frederic , Loyet Raphaël , Moore David , Ouaked Achour , Snell John , Eames Matt , Chatillon SYLVAIN , Lafon Cyril
Published: October 2018

Transcranial focused ultrasound (FUS) is a non-invasive therapeutic modality that can be used to treat essential tremor via local thermal ablation of a small spot in the thalamus. Acoustic energy is focused through the skull using a multi-element transducer. Per-element phase delay is derived using individual patient’s skull CT to compensate for skull heterogeneity, but MRI thermometry is still required for precise targeting and localization of the focal spot. There exists an opportunity for improved and accurate numerical simulations through skull to improve focal spot positioning and treatment, to allow treatment pre-planning, and to permit parametric studies that will identify important acoustic and thermal properties of human skull bones and tissues. Here, we report on a novel 3D numeric simulation framework, based on the CIVA Healthcare simulation platform, to simulate propagation through skulls and the resulting heating. This simulation platform has been developed to pilot various fast algorithms and to simulate the heating in tissues induced by FUS by solving Pennes’ BioHeat Transfer Equation. Simulations of propagation through human skulls with the Insightec 650 kHz clinical system, with 1024 elements, were performed and validated by comparison to experimental acoustic signals acquired with a hydrophone and to MRI thermometry data.
Implementation of a dynamic ray tracing method in CIVA HealthCare HIFU simulation platform—Application to the propagation in inhomogeneous and heterogeneous tissues
Authors: Chatillon Sylvain , Loyet Raphaël , Chavrier Françoise , Bouakaz Ayache , Chapelon Jean-Yves , Leberre Stéphane , Calmon Pierre
Published: October 2018

For several years, CEA-LIST has been developing in partnership with INSERM, a HIFU simulation platform, CIVA Healthcare. It provides specific tools for the development and optimization of probes and therapeutic protocols in order to target clinical problematic of specific organs. This platform allows to easily simulate 3D pressure field induced by HIFU, in linear and non-linear regimes, and the corresponding thermal dose in tissues and phantoms. In this communication, we propose a particular focus on the dynamic ray method for linear acoustic propagation. This model enables fast simulations of HIFU propagation in heterogeneous configurations, including soft and hard tissues, made of isotropic and anisotropic medium, with homogeneous or inhomogeneous elastic properties. The contribution of a source point located on the emitting surface is obtained considering the evolution of a pencil of rays centered on the geometrical path linking this source and the observation point. This models takes into account the propagations of bulk waves in each medium and the various reflections and refractions, with and without mode conversion, at each interface. Examples of computation of pressure fields through hard tissues (bones, skull) and in heated soft tissues will be presented. [Work supported by French Nation Research Agency (ANR SATURN -15-CE19-0016).]
Time course of the vasoactive response for sonoreperfusion therapy using long tone burst ultrasound
Authors: Yu François , Chen Xucai , Zhu Jianhui , Villanueva Flordeliza , Pacella John
Published: October 2018

We have previously shown that sonoreperfusion (SRP) using ultrasound (US) and microbubble (MB) can restore perfusion following microvascular obstruction and is mediated by nitric oxide vasodilation. Here, we compared the use of short (SP-10 cycles) and long (LP-5000 cycles) pulses for SRP and investigated the vasoactive response time-course and the downstream signaling 4 h post-treatment. In a rat hindlimb, we applied LP or SP (1 MHz,1.5 MPa) with the same number of acoustic cycles for 2 min during MB infusion. Both pulses affected the perfusion rate but with distinct temporal responses. For SP, the flow rate peaked (12.3±3.4 dB/s) at 15 min but returned to baseline (BL)(3.2±0.8 dB/s) after 60 min. Conversely, for LP, the flow rate also initially dropped but started to increase at 6 min and peaked (13.0±2.1 dB/s) at 15 min and was still high (8.3±2.0 dB/s) after 4 h compared to BL and SP. This sustained increase in flow rate, which was different from reactive hyperemia, was concordant with 2.5-fold increases in phosphorylated and total eNOS expression (Western blot) compared to untreated tissue, and consistent with a 2-fold increase in eNOS transcription (qPCR). These data support that long pulse SRP therapy increased in muscle perfusion for at least 4 h consistently with increased eNOS transcription and expression.