bluuebunny/crossref_metadata_2025 huggingface dataset:
Speaker tracking using SincNet for multi-channel naturalistic audio corpora: Apollo 11 fearless steps
Authors: Chandra Shekar Meena , Hansen John H. L.
Published: November 2019

Apollo-11 was the first manned space mission to successfully bring astronauts to the moon and return them safely. As a massive collaborative effort, with astronauts flying the missions in outer space, the entire communications between flight controllers, their backroom support teams and, astronauts have taken place inside NASA Mission Control Center. The communications stemming from the experienced team of scientists, engineers, and technicians who worked collectively behind the scenes in the MOCR have not been identified. In this study, we propose to identify the speakers in the Mission Control Room for a small subset of 100 h derived from a collective 19 000 h of Apollo-11 audio data, which correspond to three challenging phases of the mission: lift-off, lunar landing, and lunar walking. The speaker identification solution explores a convolutional neural network architecture called SincNet across all three Apollo-11 phases. The speaker models obtained from the subset of 100 hours will be used to track speakers on the complete corpora. Our goal is to make it possible to be able to access each individual speaker involved with the Apollo 11 mission.
Frequency-based multiband adaptive compression for hearing aid application
Authors: Patel Kashyap , Shankar Nikhil , Panahi Issa M.
Published: November 2019

Multiband Dynamic Range (MBDR) Compressor is the heart of signal processing in hearing aid devices (HADs). Operating speed of the MBDR compressor plays an important role in preserving the quality and intelligibility of the output signal. Traditional fast-acting compressor preserves the audible cues in quiet speech but, in presence of surrounding noise, it can degrade the sound quality by introducing pumping and breathing effects. Alternatively, slow-acting compressor maintains the temporal cues and the listening comfort but may provide inadequate gain for soft inputs that come right after loud inputs. HADs may operate in a variable acoustic environment. Therefore, a fixed speed in compression might affect the performance of the hearing aids. In this study, we propose a frequency (FFT) based nine-band adaptive MBDR compression which uses spectral flux as a measure of the intensity change in input level to adapt the speed of the compressor in each band. Gain, threshold and compression ratio of the compressor for nine bands are adjusted based on the audiogram of the hearing impaired patient. The proposed frequency-based adaptive MBDR compression method is implemented on smartphone. The objective and subjective test results demonstrate the performance of proposed method compared to fixed compression approach in different acoustic environments.
Modeling acoustic cues to distinctive features in a lexical speech analysis system
Authors: Nguyen Hoang , Choi Jeung-Yoon , Shattuck-Hufnagel Stefanie
Published: November 2019

Acoustic cues are robust elements that can be used to infer information contained in the speech signal, such as underlying linguistic distinctive features and the words intended by the speaker (Stevens JASA 2002). Yet, most current automatic speech recognition systems do not take advantage of a feature-cue-based framework for signal analysis. In this project, a set of common acoustic cues has been explicitly modeled by Gaussian mixture models. This set of acoustic cues can provide evidence for the overall phoneme and word sequences of an utterance. The extracted cues and their values can also determine a speaker’s linguistic production pattern, i.e., the systematic context-governed modifications in surface-phonetic form that occur pervasively in conversational speech. The simple Gaussian mixture model representation structure reduces the need for extensive amounts of training data, in contrast to conventional schemes based on large neural networks.
Underwater object localization using compressive sensing
Authors: Liana Margiasih P. , Arifianto Dhany , Wirawan Wirawan
Published: November 2019

In this paper, we propose a technique to localize a moving submerged object with a sparse measurement using a hydrophone array. We used a natural muddy pond bottom with 9 m length, 5.5 m width, and 2 m depth. First, we measured the pond impulse response to identify the sound propagation characteristics. In the second phase namely static direction of arrival (DOA), the underwater speaker was placed at half-circle positions with respect to the array to simulate the underwater object trajectory, 0 deg, 30 deg, 60 deg, 90 deg, 120 deg, 150 deg, and 180 deg, respectively. The sound generated by a four-blade propeller submarine toy was measured to track its trajectory as a dynamic DOA measurement. The measured data were transformed into discrete cosine transform coefficients and reconstructed sparsely by using the basis pursuit algorithm. Based on the estimated incident angle and time delay, the reconstructed measurements were then compared to full dictionary measurement. The results showed that the error angle of the origin deviated about 2.5 deg with half of the measured data were lost. This may suggest that the sound propagation was degraded due to bottom reverberation and scatterers. Currently, we do a similar measurement in an open shallow water environment to eliminate the reverberation.
Using relative channel impulse responses to train a machine learning algorithm for 2-D surface ship source localization
Authors: Durofchalk Nicholas C. , Ali Arslan , Mukhopadhyay Saibal , Romberg Justin , Sabra Karim G.
Published: November 2019

Underwater source localization using receiver arrays is often achieved with a purely model-based approached, i.e., matched-field processing using simulated replica-field. However, these approaches only yield reasonable predictions if the complicated ocean environment can be precisely described, which is often a daunting task. Alternatively, by turning to a data-driven approach, source localization can be achieved without the strong dependence on model-parameters. Recently, source localization in the Santa Barbara Channel (∼580 m depth, downward refracting profile) has been achieved via measurements of ships of opportunity, and machine learning classifiers. In this presentation, relative channel impulse responses, estimated via the ray-based blind deconvolution, are used to train a neural network to predict the latitude and longitude of a surface ship within the Santa Barbara Channel. Localization results for simulated and experiment data are presented and implications for future work are discussed.
Support vector machine for underwater acoustic signal range and environment classification
Authors: Herron Stephanie , Neilsen Traci , Van Komen David F. , Knobles David P. , Dahl Peter H. , Dall'Osto David R.
Published: November 2019

While machine learning has become increasingly popular as a means to learn information from large datasets, the question remains how different machine learning models can best be used to improve source ranging and environmental classification. In the current research, machine learning is used to predict the distance and depth of an impulsive source and the seabed type given a set of acoustic signals in a shallow-water ocean environment. Multiple machine learning models have been developed for this problem, including a support vector machine classifier. This support vector machine was trained on synthetic datasets of varying sizes and characteristics to predict a class corresponding to source-receiver range and seabed type. The trained model was able to classify synthetic acoustic signals with eighty-five to ninety percent average accuracy. The trained model is also applied to pressure time series signals recorded on the APL-UW Intensity Vector Autonomous Receiver system during SBCEX. Future work will continue to compare the efficiency and accuracy of support vector machines against other types of machine learning in underwater acoustics. [Work supported by the Office of Naval Research.]
Research on shallow sea multiple ocean bottom seismometer positioning with GNSS/acoustic technique and echo sounder
Authors: Liu Huimin , Wang Zhenjie
Published: November 2019

Abstract: The Global Navigation Satellite System (GNSS) combined with acoustic technique has achieved significant economic benefits in oil exploration. During positioning of ocean bottom seismometers, hundreds of underwater transponders attached to seismometers are typically deployed. In order to improve the positioning accuracy of multi-sensor in shallow water, this paper analyses the ship GNSS data, Long baseline system (LBL) and single-beam bathymetric data, and presents the solution method of multi-target underwater acoustic positioning in shallow water with the depth constraints. Combined with the Natural Neighbor Interpolation (NNI) method, the regional elevation model is constructed, and the transponders elevation interpolation is performed in the horizontal position of robust estimation solution. According to the symmetry observation and the smooth terrain of the construction sea area, the bending error of the sound line is further eliminated by using the new piecewise incident model of the sound line bending to improve the plane positioning accuracy of the multi-target underwater in shallow water. Experiments in the South China Sea show that the new method model is more stable, has better anti-gross error performance, and effectively improves the accuracy of positioning under the condition of inaccurate sound velocity measurements and more gross errors of observation data.
Automated machine learning approaches for humpback whale vocalization classification
Authors: Mohebbi-Kalkhoran Hamed , Zhu Chenyang , Ratilal Purnima
Published: November 2019

The vocalization behavior of humpback whales was previously studied and mapped over instantaneous wide areas of the Gulf of Maine (GOM), spanning more than 100 km in diameter, using the passive ocean acoustic waveguide remote sensing technique during their Fall feeding season. Acoustic signals were received on a 160-element hydrophone array system where beamforming was employed to significantly improve signal-to-noise ratio of the received vocalizations. The humpback whale vocalizations can be divided into two classes, song and non-song calls. Song vocalizations are composed of repeatable set of phrases with consistently short inter-pulse intervals. The non-song vocalizations, such as ‘bow-shaped’ and ‘downsweep’ moans, have large and highly variable inter-pulse intervals and no repeatable pattern. Here we employ machine learning approaches to classify humpback whale vocalizations into song and non-song calls. Preprocessing methods including frequency filtering, wavelet denoising, beamforming, and spectral smoothing are applied. Several automated classification methods including Support Vector Machines, Gaussian Naive Bayes, and Neural Networks are explored. Implementation of these algorithms on the GOM dataset results in over 88% classification accuracy implying the machine learning approaches can be used in field studies for real-time classification.
Acoustic characteristics of three bladderless fishes
Authors: Yan Naizheng , Mukai Tohru , YAMAMOTO JUN , HASEGAWA KOHEI , Kudo Naoyuki
Published: November 2019

The acoustic characteristics of bladderless fishes were examined by measuring the target strength (TS) of three species, pointhead flounder (flat-shaped), Arabesque greenling (spindle-shaped) and sandeel (cylinder-shaped). TS measurements were collected in a seawater tank (10 × 6 × 5 m) using the EK80 echo sounder (Simrad, Norway) and ES70-7C transducer (Simrad) over a frequency range of 45–90 kHz with a tether method. After TS measurement of the whole fish, we separated the flesh from the body (for pointhead flounder and arabesque greenling) and measured the TS of the head and bones. Pitch angle characteristics were measured from a head-down orientation (−30 deg) to a head-up orientation (30 deg), and TS was processed using Echoview 9 software (Echoview, Australia). TS patterns were examined with respect to orientation using the distorted-wave Born approximation model. The standard length, width, and height of fish were inputted into the model. The three bladderless fishes tested have different body shapes, meaning different areas are exposed to sound waves at the same body length. Therefore, the relationship between TS and the cross-section of the dorsal aspect of bladderless fish is discussed. [Work supported by the Sasakawa Scientific Research Grant from The Japan Science Society.]
Silver Medal in Musical Acoustics 2019: Murray Campbell
Authors: Campbell Murray
Published: November 2019

The Silver Medal is presented to individuals, without age limitation, for contributions to the advancement of science, engineering, or human welfare through the application of acoustic principles, or through research accomplishment in acoustics.
Case study: Acoustic considerations, modelling, and auralization for large scale acoustic sculptures
Authors: Valmont Elizabeth , Smith Brendan
Published: November 2019

This paper summarizes the research, measurements, observations, and modelling undertaken during the acoustic design of a sonic sculpture called Tower of Voices, part of the Flight 93 National Memorial in Stoystown, PA. The Tower of Voices is a 93 foot tall concrete tower featuring 40 large-scale wind chimes ranging in length from 5 to 10 feet. Due to the unprecedented nature of this project, the acoustic behavior of the chimes and interaction with the tower were the primary focus to achieve the goals of the client and designer for the soundscape visitor experience. Chime prototype mockups were undertaken to measure, record and observe sound propagation from the chimes, including the effects of different striker weights, damping materials, impact velocities, and strike locations. Acoustic modeling was utilized to assess the effect of tower shaping on the acoustic experience at various locations around the tower. An auralization was then prepared and presented in the Arup SoundLab to assist with design decisions regarding chime loudness and tower shaping. This project process of mockups, measurements, modelling, and auralization is described herein, along with a general recommended framework which can be applied to the acoustic design of large scale acoustic sculptures of many types.
Soundscape design using sound tube—To listen to voices, waves, wind, and footsteps
Authors: Shimoda Hidemaro , Shono Taiko
Published: November 2019

In modern public architecture, a large amount of glass is often used as the material, and the space is visually connected by its transparency. However, on the other hand, the soundscape is divided. In the project of “Chino Cultural Complex,” we intended to connect the two spaces through sound. This consists of a sound tube running approximately 20 m through underground of the courtyard. By speaking into one end of the tube, participants can converse with counterparts only faintly visible on the other side, with the voice as clear as if they were close to the ear. In this paper, we show the basic experiment of the sound tube in the anechoic chamber. We found an appropriate diameter of the tube in which the human voice was easy propagating on each other. Then, sound tube is covered with the absorbing materials and is set by the anti-vibrating suspension in the box culvert on site. The anti-vibration structure protected transmission of the structure-bone sound except voices to the sound tube. In other projects, we have designed this sound tube to listen to sound of waves, wind, and footsteps. We hope that these activities will provide significant soundscape design.
The changing soundscape of the performing arts lobby
Authors: Nelson Smid Jennifer
Published: November 2019

A lobby is traditionally the formal entrance to a performance venue. It can act as a buffer from the urban environment and be used by patrons before, during and after performances. In multi-venue performing arts centers, it can also act as buffer space between performances. An urban resurgence has seen younger populations move into cities and stay, and performance venues are adapting to serve the new populations. Performing artists have creatively extended their reach into the lobby using its spaces for lectures, pre and post performances, social gatherings and exhibits. Lobbies are becoming active during most of the day and evening, breaking down the acoustic buffer that they once held. This paper will focus on a soundscape study produced of several multi-performance venues that are finding creative ways to use their lobbies. It includes the identification of the activities that are taking place there, how these activities impact the main performance venues, and solutions to maintain the traditional functions of the lobby, whilst providing the active spaces needed for the future.
The importance of ongoing observations in educational spaces to understand and reflect changing acoustical environments
Authors: Shin Sang Bong
Published: November 2019

In the past, observations to understand room acoustics were considered as an important tool and were performed to establish and develop acoustic experiments, parameters, and measurements. As the objective data have been collected, the standardized methods have been playing important roles in judgment and improvement of acoustical environments in educational spaces. These days, the standards for experiments or measurements have been commonly used to understand the quality of acoustic environments. Architectural soundscape has strongly suggested ongoing observations in order to reflect changing acoustic environments even though they show reliable and concrete data. For example, as the transition of educational environments has been made, the roles of teachers and students have been expanding to ones of each other. Also, the perceptions of sound have been rapidly changing since teachers’ and students’ diverse experience of industrial and electrical sonic environments have been changing rapidly. In this paper, observations on acoustic events in classrooms were taken to understand the changes in acoustical environments based on architectural soundscape in order how to change measurement settings or analysis methods. Also, acoustical measurements were conducted with diverse measurements setting including various positions of sound sources and receivers based on diverse educational arrangements shown in the results of the observations.
A geospatial model of the global ambient soundscape
Authors: Lympany Shane V. , James Michael M. , Salton Alexandria R. , Calton Matthew F. , Gee Kent L. , Transtrum Mark K. , Pedersen Katrina
Published: November 2019

Humans and nature form an intricately coupled system with the ambient soundscape: anthropogenic, biological, and geophysical sources produce the sounds that comprise the soundscape, and, in turn, the ambient sound level affects the behavior and well-being of humans and animals. To assess the impact of the soundscape on both humans and animals, it is necessary to understand how the ambient sound level varies in space and time. A model for the ambient sound level was developed based on an ensemble of machine learning algorithms, which were trained using more than one million hours of ambient acoustic measurements acquired at hundreds of geospatially diverse locations across the United States. The resulting model predicts the ambient sound level based on geospatial features such as nighttime lights, land cover, population, climate, topography, hydrology, and transportation. A database of geospatial features with worldwide coverage was created, and the model was applied to predict the time-varying ambient sound level across the entirety of Earth’s land surface. Furthermore, the relative contributions of anthropogenic and natural sources to the soundscape were estimated by artificially changing the values of various geospatial features and reapplying the model. [Work funded by an Army SBIR.]
An interactive machine learning toolkit for classifying impulsive signals in passive acoustic recordings
Authors: Frasier Kaitlin E. , Solsona Berga Alba , Hildebrand John , Cohen Rebecca , Wiggins Sean M. , Garrison Lance , Cholewiak Danielle , Soldevilla Melissa
Published: November 2019

A typical wide-bandwidth passive acoustic seafloor sensor can record tens of millions of impulsive signals produced by biological, anthropogenic, and physical sources each year. Sources include echolocating toothed whales, snapping shrimp, ship propeller cavitation, echosounders, and weather. The volume and variety of detections make manual classification by human analysts unmanageable without in-depth knowledge of the overall acoustic context of each monitoring location. We describe an interactive machine learning toolkit in development for efficiently detecting and classifying short, highly variable impulsive signals in large passive acoustic datasets. Modules include a configurable event detector, an unsupervised clustering module for identifying dominant signal categories, a deep learning unit for learning and applying event classes, and a graphical user interface for viewing, correcting and evaluating detectors and classifiers. These tools are discussed and illustrated in the context of efforts to extract distinctive features of toothed whale clicks from towed array recordings collected by NOAA SEFSC and to use them to classify detections in unlabeled seafloor sensor recordings. The goal of the toolkit is to facilitate classification of individual signals to species in very large PAM datasets across sensor types and monitoring locations, and to improve quantitative assessment of these sources.
BirdVox: From flight call classification to full-season migration monitoring
Authors: Lostanlen Vincent
Published: November 2019

The BirdVox project aims at inventing new machine listening methods for the bioacoustic analysis of avian migration at the continental scale. It relies on an acoustic sensor network of low-cost, autonomous recording units to detect nocturnal flight calls and classify them in terms of family, genus, and species. As a result, each sensor produces a daily checklist of the species currently aloft, next to their respective individual counts. In this talk, I describe the research methods of BirdVox and their implications for advancing the understanding of animal behavior and conservation biology. The commonality of these methods is that they tightly integrate data-driven components alongside the induction of domain-specific knowledge. Furthermore, the resort to machine learning is not restricted to supervised acoustic event classification tasks, but also encompasses audio representation learning, few-shot active learning for efficient annotation, and Bayesian inference for adapting to multiple acoustic environments. I conclude with an overview of some open-source software tools for large-scale bioacoustics: librosa (spectrogram analysis), pysox (audio transformations), JAMS (rich annotation of audio events), muda (data augmentation), scaper (soundscape synthesis), pescador (stochastic sampling), and mireval (evaluation).
Arctic acoustic transmission loss variability due to ice cover during the year 2016–2017
Authors: Dzieciuch Matthew , Worcester Peter F.
Published: November 2019

Over the course of one year, underwater acoustic transmissions were made in the deep-water of the Beaufort Sea as part of the Canada Basin Acoustic Propagation Experiment (CANAPE). The transmissions were monitored at a variety of ranges (100–300 km)and the low-frequency signals (200–300 Hz) showed a strong sensitivity to the evolving ice cover. As the ice cover grew from absent in the mid-September, to its thickest and roughest in late April, the transmission loss grew also. The experimental setup included the ability to beamform so that the arrival pattern could be easily resolved into early individual ray-paths and late near-surface arrivals. This capability was used to estimate the TL variation with the angle of interaction with the ice and with the number of ice reflections. The thickness of the ice cover and roughness was monitored at 6 mooring sites. This allows one to compare the measured losses to the expected loss from the ice-free state. The amount of excess loss can then be estimated via the method of small perturbations for example.
Broadband inversion in the seabed characterization experiment with a moving source
Authors: Michalopoulou Zoi-Heleni , Gerstoft Peter
Published: November 2019

Sequential filtering and linearization for inversion of geometry and sediment parameter estimation in an oceanic environment can be achieved by employing particle filtering and linearization for a single source location. The inversion is here performed with linear frequency modulated signals received at vertically separated phones during the Seabed Characterization Experiment for a source moving towards and away from the receiving array. Short-range measurements allow the identification of some multipath arrivals, whereas others present us with a challenge. The filter, in combination with a simple cross-correlation, acts as a high-resolution estimator, allowing the extraction of four probability densities for arrival times. Arrival times are extracted for each source location. At every location, inversion is performed using the arrival time densities and both linearization and an exhaustive search relating unknown parameters to multiple paths. The results are validated by taking into consideration estimates at neighboring sites. We extract sediment sound speed and thickness assuming both a sound speed gradient and a sediment isovelocity profile and compare the results. [Work supported by ONR.]
Drug delivery and treatment of neurodegenerative disease using focused ultrasound
Authors: Konofagou Elisa
Published: November 2019

Current treatments of neurological and neurodegenerative diseases are limited due to the lack of a truly non-invasive, transient, and regionally selective brain drug delivery method. The brain is particularly difficult to deliver drugs to because of the blood-brain barrier (BBB). The BBB prevents most neurologically active drugs from entering the brain and, as a result, has been isolated as the rate-limiting factor in brain drug delivery. Until a solution to the trans-BBB delivery problem is found, treatments of neurological diseases will remain impeded. Methods that combine Focused Ultrasound (FUS) and microbubbles have been shown to offer the unique capability of noninvasively, locally and transiently opening the BBB so as to treat central nervous system disease. Four of the main challenges that have been taken on by our group and discussed in this paper are (1) assess its safety profile, (2) unveil the mechanism by which the BBB opens and closes, (3) control and predict the opened BBB properties and duration of the opening, and (4) assess its potential in neurotherapeutics. Findings in both small (mice) and large (non-human primates) animals will be shown as well as its clinical translation for the treatment of neurodegenerative disease such as Alzheimer’s and Parkinson’s.
FUS-LBx: Focused ultrasound-enabled brain tumor liquid biopsy for noninvasive brain cancer diagnosis
Authors: Chen Hong , Zhu Lifei , Pacia Christopher P. , Nazeri Arash , Yang Yaoheng , Gach H. Michael , Liu Weijun , Wang Xiaowei , Petti Allegra , Dunn Gavin , Leuthardt Eric
Published: November 2019

Focused ultrasound (FUS) in combination with microbubbles has been studied extensively as a blood-brain barrier (BBB) disruption tool for the delivery of drugs in the blood circulation to the brain parenchyma. Recently, we introduced the hypothesis that FUS-mediated BBB disruption could be viewed as a tool for enhancing “two-way trafficking” between brain and blood. While circulating molecules can be allowed to enter the brain using FUS-mediated BBB disruption, brain tumor biomarkers can also be released into the blood circulation for liquid biopsies. Based on this hypothesis, we proposed to develop FUS-enabled brain tumor liquid biopsy technique (FUS-LBx), which uses FUS in combination with microbubbles to enhance the release of biomarkers from brain tumors into the blood circulation for liquid biopsies. We performed a proof-of-concept study and demonstrated the feasibility of FUS-LBx for the local release of mRNA from glioblastoma tumors in mice into the bloodstream for liquid biopsies. We also optimize the FUS-LBx technique by investigating the effects of FUS acoustic pressure on the tumor biomarker release level and potentially associated hemorrhage burden. We found that FUS-LBx technique can be optimized to be a safe and effective image-guided biomarker release technique. We developed an MR-compatible FUS system for FUS-LBx application in a porcine model and demonstrated the feasibility and safety of FUS-LBx in the large animal model. In summary, FUS-LBx is a promising tool for brain tumor diagnosis.
Inertial cavitation behaviors and bioeffects in pulsed focused ultrasound
Authors: Khokhlova Tatiana D. , Bawiec Christopher , Peek Alex T. , Rosnitskiy Pavel , Kreider Wayne , Maxwell Adam D. , Khokhlova Vera A. , Son Helena , Wang Yak-Nam , Totten Stephanie , Sapozhnikov Oleg A. , Hwang Joo Ha
Published: November 2019

Pulsed HIFU-induced inertial cavitation can be used to permeabilize tissue for promoting drug extravasation and penetration. In addition to HIFU frequency, peak rarefactional pressure (p-), and pulse duration, the threshold for inducing inertial cavitation has recently been correlated with nonlinear distortion of the focal waveform. Here, the effect of nonlinear distortion and HIFU frequency within the range of 0.28–1.9 MHz were investigated in transparent gel phantoms with simultaneous high-speed photography and passive cavitation detection (PCD). Transducers with different F-numbers (0.77–1.5) delivered 1 ms-long pulses with varying p- (1–15 MPa) at 1 Hz pulse rate. For all frequencies, increasing acoustic power and nonlinear distortion led to bubble behaviors changing both quantitatively and qualitatively from isolated, stationary bubbles to sparse bubble clouds that proliferated slowly towards the transducer. Different behaviors corresponded to specific spectral characteristics of the PCD signals. Exposures corresponding to particular behaviors at 1 MHz and 0.3 MHz frequencies were then applied to surgically exposed porcine liver, kidney, and pancreas in vivo with concurrent administration of Evans Blue Dye (EBD). Exposures with spectral signatures of proliferating bubbles on PCD corresponded to enhanced EBD extravasation and hemorrhagic injury to all tissues. [Work supported by NIH R01EB023910 and R01CA154451.]
Defining a nuclei-independent unified cavitation dose for the spatiotemporal quantification of cavitation-mediated bioeffects by passive acoustic mapping
Authors: Smith Cameron , Coussios Constantin
Published: November 2019

Cavitation can be seeded in vivo using a variety of nucleation agents with differing acoustic responses. The development of passive acoustic mapping (PAM) now makes it possible to spatio-temporally quantify the spectral content of acoustic emissions from cavitation. We present an approach that uses PAM to provide set-up independent measures of spatially dependent cavitation dose in units of Joules, and relate it to a readily quantifiable global bioeffect: the haemolysis of equine blood mixed with either micron-sized or sub-micron cavitation nuclei over a range of concentrations. Using two orthogonal L11-5 128-element arrays to achieve a 400-μm PAM resolution, the acoustic exposure parameters from a focused 0.5 MHz ultrasound transducer were varied from 0–2 MPa, and 50–50 000 cycles at 5% duty cycle to span a range of cavitation doses. A monotonic relationship between cavitation dose and haemolysis was identified, irrespective of the acoustic pressure, pulse length, cavitation agent or concentration used. The validity of this metric was tested further by using PAM to simultaneously monitor cavitation dose and haemolysis in multiple locations within a tissue phantom. These results lay the foundation for a unified and set-up independent cavitation dose metric for spatio-temporal monitoring of the safety and efficacy of cavitation-based therapies.
Real-time imaging and control of boiling histotripsy lesion formation using Doppler ultrasound
Authors: Khokhlova Vera A. , Bawiec Christopher R. , Cunitz Bryan W. , Sapozhnikov Oleg A. , Khokhlova Tatiana D.
Published: November 2019

In boiling histotripsy (BH), millisecond-long HIFU bursts with shocks are used to mechanically liquefy tissue. Most BH studies have been performed under real-time B-mode ultrasound imaging of bubbles generated at the treatment site. However, such approach does not allow quantitative assessment of the degree of tissue liquefaction. In addition, aberration and clutter often limit the echogenicity introduced by bubbles. In this work, plane wave Doppler followed by B-mode imaging were implemented immediately after each BH pulse to visualize residual bubble motion during volumetric BH treatments in ex vivo bovine liver. The changes in the Doppler power and speed were used as metrics to assess the degree of tissue liquefaction. An ATL P6-3 imaging probe connected to a Verasonics Ultrasound Engine (VUE) was mounted in the central opening of a 256-element 1.5 MHz HIFU array driven by another VUE with 1.2 kW external power source enhanced by a capacitor bank. The proposed imaging sequence improved BH targeting and bubble visualization. As tissue liquefaction progressed from partial to full (single versus five BH pulses per focal spot), both Doppler power and residual bubble velocity directed away from the transducer increased (7-fold and 10 cm/s to 20 cm/s, correspondingly) and then saturated. [Work supported by NIH R01EB7643.]
Histotripsy in collagenous tendons
Authors: Smallcomb Molly , Simon Julianna C.
Published: November 2019

Histotripsy is a high intensity focused ultrasound modality that uses cavitation bubble clouds or shock wave heating and millisecond boiling to mechanically fractionate most soft tissues. However, highly collagenous tissues like tendon have proven resistant to histotripsy fractionation. Previous work has shown that cavitation occurs during treatment but does not necessarily equate to detectable damage. In this study, collagen gels and ex vivo large animal Achilles tendons were exposed to focused ultrasound at 1.5 MHz, 1.07 MHz, or 3.68 MHz with 0.005–10 ms pulses repeated at 0.001–1 Hz for 15–60 s with acoustic pressures up to p +  = 88 MPa, p− = 20 MPa. A research ultrasound system was used to monitor for hyperechogenicity during the exposure. Tendon samples were collected and stained with hematoxylin and eosin (H&E) for analysis of cellular morphology and nicotinamide dinucleotide diaphorase (NADH-d) for analysis of enzymatic activity. Preliminary results show thermal denaturation rather than mechanical fractionation in tendon. Pilot studies in collagen gels show successful fractionation with histotripsy. Additional parameters will be evaluated on collagen gels and ex vivo tendon to promote mechanical fractionation rather than thermal denaturation. [Work supported by Penn State College of Engineering Seed Grant, NIH NIBIB EB027886, and NSF Graduate Research Fellowship DGE1255832.]
Acoustic manipulation of large solid objects for medical applications
Authors: Ghanem Mohamed A. , Maxwell Adam D. , Sapozhnikov Oleg A. , Bailey Michael R.
Published: November 2019

Most progress in acoustic manipulation through radiation forces has been achieved in the trapping and levitation of small and low-density objects. We are developing traps to manipulate large dense objects. Such technology could be used to noninvasively steer a kidney stone along a complex path in the kidney fluid space to pass a small stone before it is symptomatic. In this work various acoustic beams were generated with a focused, 1.5-MHz, 256-element array and used to trap, levitate, and manipulate in three-dimensions (3-D) 3-5 mm glass spheres. The radiation forces from these beams were simulated and measured for different target and trap sizes. Good agreement between calculations and measurements of the forces was found, with an average discrepancy of 12 %. At 10-W acoustic power, the lateral trapping forces were 0.5–3 times the gravitational forces in water. 3-D stability and off-axis steering were achievable only when the ratio of beam diameter to the target diameter was ≳1. Glass spheres placed in the focus of the array were manipulated over a preprogrammed 3-D path at pressure and intensity levels safe for clinical exposure. [Work supported by NIH P01-DK043881, K01-DK104854, R01-EB007643, and RBBR 17-02-00261.]
Infrasound microphones using microfabricated piezoresistive silicon diaphragms
Authors: Williams Randall P. , Seo Yoonho , Stalder Carly A. , Avenson Bradley D. , Buoy Quinlan S. , Kim Donghwan , Hall Neal A.
Published: November 2019

We report on the development of a new digital infrasound measurement system with integrated digitizing electronics. The system was designed to meet an input-referred noise floor specification of 95 μPa/√Hz over the frequency range of 0.01 Hz to 100 Hz. The infrasound sensor uses a microfabricated silicon diaphragm with four integrated piezoresistors connected in a full-bridge configuration. Fabricating the sensing element on a silicon wafer using conventional micro-electromechanical systems (MEMS) processing techniques is a convenient approach for realizing sensitive diaphragms with integrated piezoresistors, and, in turn, sensing elements that intrinsically respond to DC. This approach is thought to be suitable for large infrasound arrays. Integrating a secondary transducer into the package provides self-test capabilities, along with a geophone for correlating infrasound signals with seismic vibrations. Sensor self-noise and sensitivity measurements are presented, along with a discussion of system design considerations, including design of the electronics and packaging.
Fly-inspired microphones with piezoelectric readout
Authors: Stalder Carly A. , Kim Donghwan , Seo Yoonho , Hall Neal A.
Published: November 2019

The directional hearing capabilities of the fly Ormia Ochracea have been known and utilized in MEMS devices since the 1990s. The fly locates crickets by listening to their chirps—an amazing feat when one considers the size of the fly’s ear compared to the wavelength of audible sound. This work will focus on the design, modeling, fabrication, and testing of a biologically inspired microphone that harnesses this fly’s hearing ability. Recent prototypes are 1/16th the size of previously fabricated devices of similar design and match the true size of the fly’s hearing mechanism. The device consists of a two-sided cantilever beam that rotates about torsional pivots, resulting in two main frequency modes that can be used in the sound localization process for in-plane directivity: a gradient mode that causes the two sides of the beam to move out-of-phase, and a symmetrical mode that causes the two sides of the beam to move in-phase. The microphones are fabricated on a silicon-on-insulator wafer with a 2-μm-thick device layer. A 500-nm-thick aluminum nitride film is the piezoelectric transduction material. The main sensing modes are shown in multipoint scans and are accurately modeled with the finite element method.
Preliminary analysis of operating conditions of acoustic sounder (SODAR) before the installation
Authors: Kumar Nishant , Soni Kirti , Agarwal Ravinder , Singh Mahavir
Published: November 2019

The SOnic Detection And Ranging (SODAR) is a surface-based remote sensing instrument, based on Doppler effect and sound signal. This paper discusses the operating conditions of Monostatic SODAR system, error in the measured Atmospheric Boundary Layer (ABL) height by taking account of the antenna characteristics which are pulse transmission, receiving durations, spectral augmentation of the received echo and atmospheric refraction effects. The Monostatic SODAR is able to receive even very weak echo by providing a good directional response with high conversion efficiency. The location and orientation of the antenna are finalized after a detailed analysis of the site with relative to several parameters like comparative measurement of acoustic background noise and frequency response of noise. Also, before installation of the system, the transducer has to be individually characterized for it’s transmitted and received conversion efficiency, and variations in the product of these efficiencies (conversion gain). The antenna is systematically characterized, in an acoustic anechoic and reverberation chamber, with respect to its conversion efficiencies and directional response.
Study of timbral influence of mallets on the steelpan through spectral analysis
Authors: Malloy Colin
Published: November 2019

The steelpan is an instrument with unique acoustic properties that allow for a wide range of timbral possibilities influenced by the choice of actuator. It is increasingly common for composers and performers to experiment with mallets made from a variety of materials that produce highly differentiated timbres. Examples of mallet types include wood and aluminum shafts covered with rubber tips, chopsticks, dowel rods, and cardboard tubes. Understanding how mallets interact with the steelpan is an important aspect of performance practice. Aside from standard rubber tipped mallets, most other mallets types are homemade and these characterizations will inform mallet design and construction in order to achieve the desired timbral result. While there have been studies analyzing the modes of vibrations of steelpan notes, the interactions between mallets and timbre hasn’t yet been studied and characterized. The goal of this work is to measure and characterize the timbral influence of a wide variety of mallets on high voiced steelpans through low level audio analysis with a focus on spectral features. Audio recordings were made with more than a dozen different mallets and several steelpans of three different types: tenor, double seconds, and double tenors.
Modeling of wood resonances in prototype guitar top plates
Authors: O'Conner Mitchel , Hoffman Kurt
Published: November 2019

We present the results of using COMSOL modeling tools to explore the resonance structure of prototype guitar top plates fashioned from several different grades of spruce. Comsol provides a platform for applying acoustical analysis to a variety of objects using the finite element method. Our studies utilize these techniques to explore the nature of normal mode vibrations in spruce top plates without bracing. The calculated normal modes will be compared to measured frequencies of prototype top plates. In addition, models of different grades of wood will also be explored in an effort to clarify which wood properties affect specific physical parameters for improved modeling.
A platform for performance phase II: Evaluations of the structurally transmitted energy of the cello/performer system
Authors: Tagg David J.
Published: November 2019

Stringed instruments such as the cello have been evaluated extensively from structural and acoustical perspectives, but the riser on which a cello sits has until recently been overlooked. This riser becomes acoustically coupled and can play a productive or counterproductive role in its acoustic projection. The cellist’s performance is understood to be enriched and enhanced by this piece of furniture, and this second installment in a two-part study further investigates the mechanical interaction between the musician, instrument, and supporting surface. This was accomplished by measuring the energy transmitted through five points of interface including the performer’s heel, toe, front and rear legs of the chair, and endpin of the instrument. Results of the relative amplitude and frequency response of the structurally transmitted sound at these points, using five different performers, two performance techniques, and the full range of the instrument, will be presented.
Spectral analyses of the Ikoro drum
Authors: Onwubiko Stephen G. , Neilsen Tracianne B.
Published: November 2019

The Ikoro or Ekwe-is a wooden slit drum, a percussion instrument of the idiophone family which by virtue of its functions and its predominance in the eastern parts of Nigeria with the Igbo’s plays an important role in the Igbo musical culture and settings. The Ekwe being a drum made of wood has pitches and produces a very deep rich bass sound which can be heard from a distance and has a sustained reverberation rendering a background beat to music or sound of warning. This paper looks at the frequency domain of the sustained reverberation, measuring, and analyzing the dynamics responses of the structure upon an excitation and describes the historical and constructional process of the Ekwe.
Investigating focusing of Mach waves by Prandtl-Meyer expansion fan as an explanation for some spatiospectral lobe phenomena
Authors: Swift S. Hales , Gee Kent L.
Published: November 2019

Recent studies of high-performance aircraft have noted the presence of spatiospectral lobes: regions of physical and frequency space where the sound field exhibits increased amplitude not otherwise captured by typical jet noise models. This phenomenon results in multiple spectral peaks at particular positions and multiple spatial peaks at particular frequencies. These peaks have been variously explained as resulting from indirect combustion noise or shock-turbulence interactions of some type. This paper proposes to explain some aspects of the spatiospectral lobe phenomenon in terms of the focusing of Mach waves by the Prandtl-Meyer expansion fans that, with oblique shocks, comprise shock cells. Briefly, a higher convective velocity leads to an angle of propagation farther from the jet axis. Because the flow in an expansion fan is increasing in velocity, Mach waves produced within the latter part of a single expansion fan are directed at an angle farther to the sideline than those produced at an upstream position within the same fan, leading to converging directions of travel and focusing. A simple model is developed and used to demonstrate the explanatory power of this mechanism with input from a prior computational study.
Phononic crystal based tunable and nonreciprocal ultrasonic metamaterials
Authors: Neogi Arup , Heo Hyeonu , Ju Jaehyung , Krokhin Arkadii
Published: November 2019

Phononic crystals with asymmetric scatterers is an ideal platform to control the transmission of acoustic waves. These asymmetric scatterers has been used for nonreciprocal ultrasonic wave propagation in a fluidic medium due to the differential dissipation induced by the scatterers. The non-reciprocity of the wave-propagation depends significantly on the surface properties and the orientation of these individual scatterers. These quasi-periodic phononic structures with asymmetric scatterers can be used to modulate the propagation of the acoustic waves for an active acoustic insulator to a conductive behavior. The dispersion of the ultrasonic wave through the phononic crystal can be used to focus, beam-steer or filter the acoustic wave propagation as well as realize acoustical cavity for multifunctional applications. The localization of sound wave due to these orientation of the asymmetric scatterers has also been observed experimentally.
The ambient noise environment of the Canada Basin during the year 2016–2017
Authors: Worcester Peter F. , Dzieciuch Matthew
Published: November 2019

The Canada Basin Acoustic Propagation Experiment (CANAPE) was designed as an active underwater acoustic tomography experiment. The large amount of data (Nyquist frequency, 1 kHz) collected over the course of one year from 7 vertical line arrays allows for a unique capability to characterize the ambient sound environment in the deep-water portion of southwestern Beaufort Sea. The data shows a strong seasonal signal as the ice cover forms, grows, and recedes. There is considerable variability from day to day. Furthermore, the vertical arrays allow one to quantify the noise field by angle and depth. The Arctic is a considerably less noisy environment than the temperate ocean and it gets even quieter as the ice thickens. These measurements form an important new base line as the Arctic continues to react to changing climatic conditions.