bluuebunny/crossref_metadata_2025 huggingface dataset:
Exploring the need for language-specific hearing aid signal processing
Authors: Roy Abhijit , Souza Pamela E. , Bradlow Ann
Published: November 2022

Speech phonemes in higher frequencies have varying acoustic characteristics in different languages. For example, /s/ and /ʃ/, fricatives commonly used in English, have spectral peaks at higher frequencies than /ʂ/ and /x/, fricatives commonly used in Mandarin. Data on the relationship between the acoustic characteristics of a listener’s native language and their hearing aid signal prescription requirements could provide important clinical guidance. Non-linear frequency compression is a digital signal processing tool that compresses auditory information above a pre-determined cutoff frequency. In hearing aids, this compression is applied with the intention of making higher-frequency speech sounds more audible to listeners with high-frequency hearing loss. Here, we studied the effect of different frequency compression settings on fricative perception between Mandarin and English listeners. Normal-hearing participants between age 18 to 50 years were presented with fricative identification and fricative discrimination tasks under various frequency compression settings. Participants were grouped between those with exclusive English language background birth to 6 years to those with exclusive Mandarin language background during the same period. Results display different responses for presented phonemes and frequency compression settings, suggesting that language specificity could be considered for hearing aid signal prescription.
Bilateral cochlear implants or bimodal hearing: A comparison of quality of life
Authors: Lewis Jessica , Castellanos Irina , Moberly Aaron C.
Published: November 2022

Current literature suggests that bimodal users (i.e., individuals using a cochlear implant—CI—and a contralateral hearing aid) may report better outcomes in some listening situations (e.g., pitch perception and music appreciation) than bilateral CI users; however, several studies report conflicting results. Currently, there is no widely accepted criterion for bilateral simultaneous or sequential CI candidacy in adults, and clinicians typically rely on the patient’s experience to determine whether bilateral or bimodal hearing is best for that individual. Therefore, in this study we compare responses from twenty-four bilateral and bimodal users on the Cochlear Implant Quality of Life (CIQOL) questionnaire. Results demonstrated that bilateral CI users report better scores for the emotional, environmental, social, listening effort, and global scales than bimodal users. No significant difference in age, speech recognition abilities, and duration of hearing loss between the two groups were observed; however, the two groups did differ on their duration of CI use, such that the bimodal users had less experience listening with their CIs than the bilateral CI users. These findings do not replicate previous in-lab results, which demonstrate a bimodal user advantage and stresses the need to further explore the self-reported benefits of bimodal versus bilateral CI hearing.
Inter-articulator coordination in speech production: Timing is of the essence
Authors: Masapollo Matthew , Nittrouer Susan
Published: November 2022

In skilled speech production, sets of vocal-tract articulators work cooperatively to achieve task-specific goals, in spite of contextual variation. Efforts to understand these functional units have focused on identifying control variables responsible for allowing articulators to achieve these goals, with some research focusing on temporal variables (relative timing of movements) and other research focusing on spatiotemporal variables (phase angle of movement onset for one articulator, relative to another). Here, both types of variables were examined. Ten talkers recorded /tV#Cat/ utterances using electromagnetic articulography, with alternative V (/ɑ/-/ɛ) and C (/t/-/d/), across variation in rate (fast-slow) and stress (first syllable stressed-unstressed). Two measures were obtained: (1) timing of tongue-tip raising onset for medial C, relative to jaw opening-closing; (2) angle of tongue-tip raising onset, relative to the jaw phase plane. Results showed that any manipulation that shortened the jaw opening-closing cycle reduced both the relative timing and phase angle of the tongue-tip movement onset, but relative timing of tongue-tip movement onset scaled more consistently with jaw opening-closing across rate and stress variation. This finding supports the hypothesis that an intrinsic timing mechanism is the control variable for interarticulatory relations, with immediate compensation then allowing these structures to achieve their goals spatially.
Examination of reverberation time predictions and measurements
Authors: Keefe Joseph
Published: November 2022

This presentation will discuss reverberation time data, including measured versus predicted, occupied versus unoccupied, and calculated based on different predictive techniques. Some predicted data agree well with observed conditions, while others differ significantly. This presentation will facilitate a discussion of techniques, methods, and approaches.
One acoustician’s defect is another artist’s feature: Simulating real flutter for an art installation
Authors: Mayell Marcus R. , Dulworth Nicolaus T. , Cudequest Brandon , Glosemeyer Petrone Robin
Published: November 2022

Flutter is generally considered an acoustical defect – the timbral distortions and rhythmic nature can be distracting, annoying, or downright disruptive. The paper recontextualizes flutter as a compositional tool for sound art, particularly when the flutter of existing rooms is used for site-specific installations. Due to the global COVID-19 pandemic, the artist was unable to travel, allowing us to visit the site and take several room impulse responses. The measured spaces were parallelpiped, sound reflective, and fluttery. To give the artist creative flexibility, we simulated the rooms for an extended range of source and receiver locations informed by the in-situ measurements. This paper will discuss our calibration and modeling techniques to simulate flutter and reverberation coloration in real rooms, which is non-trivial for image source methods or ray-based software.
Applying unsupervised machine learning clustering techniques to early childcare soundscapes
Authors: Hummel Kenton , Ryherd Erica E. , Konstantzos Lason , Raikes Abbie
Published: November 2022

Early childhood is a critical time period for language, brain, cognitive, and social/emotional development. Out-of-home childcare is a normative, typical experience for millions of young children. Although Indoor Environmental Quality (IEQ) in K-12 settings has received recent, significant attention, the links between IEQ and children’s learning and development in early childcare settings is a less understood topic. This work focuses specifically on the sound aspect of IEQ in early childcare settings to better understand typical noise levels and occupant experience. Standard approaches to analyzing background noise will be presented alongside more detailed statistical analyses utilizing unsupervised machine learning clustering techniques. Noise data collected in three daycares will be presented using typical acoustic metrics and clustering techniques to better understand room activity conditions and support new metrics. Overall, this study can lead to a better understanding of daycare soundscapes and pave the way towards a better childcare for young children.
Calibrating geometrical acoustics models of non-diffuse rooms
Authors: van der Harten Arthur W. , Azevedo Matthew
Published: November 2022

A case study is presented for the challenging case in which a conference room with a strongly non-diffuse impulse response is measured, and geometrical acoustics models are built and calibrated using two separate software packages simultaneously. Both software packages are able to reproduce the measured flutter echoes, although with surprising input scattering coefficients, particularly for parallel stainless steel wall finishes. Caution is advised concerning common assumptions about scattering coefficients for operable partitions. Furthermore, the authors suggest that benchmarking for acoustics simulation software be performed in strongly non-diffuse rooms, in addition to the existing round robin studies that have traditionally been held using more normal or diffuse rooms.
Acoustic rainfall estimation with support vector machines and error correcting output codes
Authors: Berg C. J. , Mallary C. , Buck John R. , Tandon Amit , Andonian Alan
Published: November 2022

Ma and Nystuen (2005) successfully detected and estimated rainfall at sea from passive acoustics. They detected rain from three narrowband frequencies and then estimated log rainfall rate via a regression with energy in the 5 kHz band. Mallary et al. (2022) improved rainfall detection by exploiting broadband spectra while reducing the dimensionality through principal component analysis (PCA). This project builds upon Mallary’s work moving beyond detection to estimate the rainfall by quantization into discrete ranges based on PCA-reduced acoustic power spectra. The classification scheme combines multiple binary support-vector machine (SVM) classifiers (Boser et al. 1992) with Dietterich and Bakiri’s error-correcting output codes (1995) to classify acoustic PSDs into one of 6 rainfall rate classes. Evaluating the PCA/SVM classifier on 4 months of acoustic recordings and meteorological data collected from a shallow water pier in New Bedford, MA found the hourly accumulations from the rain gauge and acoustic estimates had a correlation of 0.97 ± 0.01. Emulating Ma & Nystuen’s estimator on the same data set yields a correlation of 0.76 ± 0.02. [Work supported by ONR.]
Underwater low frequency Helmholtz bubble resonator
Authors: Morozov Andrey K.
Published: November 2022

Low-frequency sound sources have found application in oceanology and geoacoustic methods of remote sensing. An underwater low-frequency sound source with a pneumatically driven bubble resonator covered with an elastic membrane effectively provides a very high source level. However, it has a narrow bandwidth, and its resonant frequency is difficult to change without changing the size of the original system. Internal acoustic resonators included in a bubble filled with gas can change the frequency response of the entire source and expand its bandwidth. Internal resonant systems can be designed so that the bubble resonator can be tuned over a wide frequency range. Other systems may add one or more internal resonances and spread the emitted spectrum over a very wide frequency band. It is possible to consider various multipole resonant systems in combination with an underwater bubble. A simple and efficient system consists of a bubble resonator and an internal Helmholtz resonator. The addition of a Helmholtz resonator converts the single resonant bubble into a double resonant system and extends its bandwidth. The theory of the underwater bubble Helmholtz resonator and various applications of these resonators for practical systems are considered. The results of the experimental verification are discussed.
Real-time passive cavitation mapping with high spatial-temporal resolution
Authors: Li Mucong , Li Daiwei , Jing Yun , Zhong Pei , Yao Junjie
Published: November 2022

Shock wave lithotripsy (SWL) and laser lithotripsy (LL) have been widely used for clinical treatment of kidney stones. Cavitation plays an important role in stone fragmentation in both SWL and LL, yet it may also contribute to renal tissue injury. It is therefore crucial to determine the spatiotemporal distributions of cavitation activities to maximize stone fragmentation while minimizing tissue injury. Passive cavitation mapping (PCM) has most practical applications in deep biological tissues and is most promising for clinical translation. We have developed a set of technologies for 2D/3D PCM that can be seamlessly integrated with ultrasound imaging and photoacoustic imaging. Our 2D/3D PCM has achieved a spatial resolution of hundreds of micrometers and a temporal resolution of several microseconds. We also developed a transient angular spectrum approach for PCM reconstruction, which is ten times faster than the traditional delay-and-sum method. Using the 2D/3D PCM system, we imaged shockwave- and laser-induced single cavitation bubbles in both free field and constricted space, as well as on large animal models. Collectively, our results have demonstrated the high reliability and spatial-temporal accuracy of the 2D/3D PCM approach, which paves the way for future in vivo applications and human studies during SWL and LL.
Detection, characterization, and spatial mapping of nucleated cavitation for drug delivery: From in-vitro-, through in-vivo to the clinic
Authors: Boulos Paul , Ellis Edward , Power Maura , Jackson Edward , Shah Anant , Pearce Charles , Szostek Patrycja , Berry Naomi , Vojtasova Erika , Alkattan Mohammed , Masiero Massimo , Crake Calum , Rowe Cliff , Coviello Christian
Published: November 2022

Cavitation-nucleation agents that stabilize gas bubbles, be they micro or nano in scale, allow for consistent and reliable induction of cavitation compared to endogenous nuclei. When these agents are used in conjunction with an ultrasound system that can perform simultaneous image-guidance to target tumors, focused ultrasound delivery to cause cavitation, and imaging of cavitation emissions as a treatment monitor, a complete drug delivery system is possible that can enhance the penetration and distribution of oncology agents into solid tumors. Development of novel, clinical cavitation agents requires, from their early prototyping through to their ultimate product release, that the detection and characterization of their cavitation performance is considered. Additionally, the methods and equipment used to detect and image cavitation both in preclinical and clinical drug delivery systems must be similarly assessed to ensure that the cavitation “dose” estimated from the agents is understood in precision to ensure reliable drug delivery. To achieve these objectives, OxSonics continues to develop, alongside its new bubble formulations, a cavitation metrology program that investigates cavitation performance and quantification, cavitation test articles and protocols, validation of these methods, and equipment calibration and qualification. This talk explores all the aspects of this from the prototyping stage to clinical deployment.
From ultrafast ultrasound imaging to “matrix imaging”
Authors: Fink Mathias
Published: November 2022

Both ultrasound medical imaging and NDT requires reflection-mode detection. As tissues, as well as many metallic samples, are complex disordered media, containing random distribution of scatterers, these techniques suffer various limitations as distortion induced by aberrating layers. A multi-illumination strategy is the solution to solve these problems. It was first used in the context of ultrafast imaging with multiple plane wave illumination. I will show that, recording a “reflection matrix” provides enough information to greatly improve beam-forming techniques. I will describe how to extract from the coherence properties of this reflection matrix enough information both to compensate the effects of aberrating layers and to provide quantitative information. Various strategies to measure this matrix and to exploit it will be discussed. This is the domain of “matrix imaging” recently developed for ultrasound imaging.
The Federal Aviation Administration (FAA) allows Americans to be exposed to unsafe levels of aviation noise
Authors: Fink Daniel
Published: November 2022

The American Public Health Association states, "Noise is unwanted and/or harmful sound." The FAA considers noise an annoyance (cf. Schultz Curve), and adopted 65 dBA Day-Night Level (DNL) as the threshold for significant aviation noise, below which residenial land uses are compatible. This is not safe for humans. According to the Environmental Protection Agency, safe noise levels are 45 dB for indoor noise, 55 dB for outdoor noise, and DNL 55 dB. The World Health Organization recommends nighttime noise levesl of only 45 dB. Recent research has established conclusively that noise is a stressor, causing a cascade of physiological events involving the autonomic nervous system, stress hormones, and inflammatory pathways, in turn causing cardiovascular disease, including hypertension and heart attacks, and other adverse health effects. Epidemiological studies demonstrating these effects have been confirmed by human and animal research. The biological mechanisms are now understood at the cellular, subcellar, molecular, and genetic levels. Additionally, aviation noise disproportionately affects poor and minority communities and vulnerable populations. A summary of this research will be presented. No more research is needed to know that aviation noise is hazardous to health. The FAA must establish lower noise standards to protect Americans exposed to aviation noise.
Realization of clinical translation of photoacoustic imaging
Authors: Iskander-Rizk Sophinese , van Soest Gijs
Published: November 2022

Photoacoustic (PA) imaging capitalizes on sound and light to probe tissue optical absorption at depth. Owing to acoustic propagation of absorbed diffuse photons it exceeds imaging depth of most pure optical methods. Moreover, since the detection of PA signals relies on ultrasound transducers, the modality inherently allows for acquisition of co-registered ultrasound images, enabling a structural and functional examination of tissue. Diagnosis of diseases such as atherosclerosis could benefit greatly from uncovering such dual information. Clinical translation of photoacoustic imaging, led by breast cancer imaging application is—pending a couple of hurdles—on the brink of happening. Systematic approaches in assessing contrast through spectroscopy, designing acquisition systems through optimization for both PA/US signal sensitivity and image metrics and finally designing instrumentation to account for tissue access limitations have been researched and show promising results. In this talk, we discuss the final challenges in translating photoacoustic imaging to the clinics with respect to contrast, instrumentation and system development.
Deep learning for fast photoacoustic wave simulations
Authors: Hsu Ko-Tsung , Guan Steven , Chitnis Parag V.
Published: November 2022

Photoacoustic tomography involves absorption of pulsed light and subsequent generation of ultrasound, which when detected using an array of sensors can produce clinically useful images. Simulation tools for photoacoustic wave propagation have played a key role in advancing photoacoustic imaging by providing quantitative and qualitative insights into parameters affecting image quality. Classical methods for numerically solving the photoacoustic wave equation rely on a fine discretization of space and can become computationally expensive for large computational grids. In this work, we apply Fourier Neural Operator (FNO) networks as a fast data-driven deep learning method for solving the 2D photoacoustic wave equation in a homogeneous medium. Comparisons between the FNO network and pseudo-spectral time domain approach demonstrated that the FNO network generated comparable simulations with small errors and was an order of magnitude faster. Moreover, the FNO network was generalizable and could generate simulations not observed in the training data.
Noninvasive tracking of solidification using ultrasound
Authors: Smith Caeden , Arguelles Andrea P.
Published: November 2022

Noninvasive tracking of solidification is typically done by monitoring the sample’s surface temperature. This approach is error-prone and not always appropriate for complex geometries and often does not provide complete information on the sample’s transitioning phases. This feasibility study investigates using ultrasonic waves to noninvasively track solidification in wax. Ultrasonic sensors are used in through-transmission mode to monitor the response over the solidification period. The difference in speed of sound between the wax’s liquid and solid phase allows for the solid fraction of the sample to be calculated over the solidification period and the time of complete solidification to be identified. Changes in attenuation during solidification are consistent across experiments. These changes are likely to provide additional information about the cast once they are fully understood. Temperature probes are used to verify the results obtained from the ultrasonic data. The ultimate goal of the project is to use a metal sample and connect information from the ultrasonic signal to the material properties and grain structure of the cast using noninvasive ultrasound technology.
Acoustic wave propagation in a toroid cavity carrying a steady flow
Authors: Thompson Charles , Kamal Sarah , Shah Nishi , Chandra Kavitha
Published: November 2022

This paper presents an analytical study of acoustic wave propagation in a toroid-shaped cavity. The interior wall of the cavity is rigid and encloses a fluid driven into steady motion along its azimuth. The analysis will focus on acoustic excitation near the principle resonance frequency of the system. The impact of steady primary and secondary flow on the acoustic velocity potential flow-reverse symmetry is evaluated.
Vibrational characteristics of a helical antenna for L-Band satellite communications
Authors: Hill Nathan , Chumley Scott W. , Prather Wayne , Mobley Joel
Published: November 2022

Helical coils serve many functions in mechanical systems and are often subjected to a variety of impulsive forces. In this talk we examine the dynamics of a helix modeled after an L-Band helical antenna used for satellite communications in low Earth orbit (LEO). Since the components of a deployed satellite are not accessible, it is critical to understand the dynamics of the antenna given its position outside of the main body. The intent of this work is to identify the frequencies, shapes and Q-values of the vibrational modes of the helix subject to impulsive stimuli and evaluate changes due to environmental exposures and structural modifications. We report on coil-by-coil measurements of the spectra using eight distinct stimulus-response polarizations. Two specific studies are emphasized in this talk. To gauge the sensitivity of the element to thermal variations under (LEO) conditions, we report on the impact of thermal cycling on the vibrational spectra of the helix. We also report on changes in the dynamic response of the helix due to the addition of structural support elements.
Transfer effects of discrete tactile mapping of musical pitch on discrimination of vocoded stimuli
Authors: Hodges Aaron , Goldsworthy Raymond L. , Fitzgerald Matthew B. , Fujioka Takako
Published: November 2022

Many studies have found benefits of using somatosensory modality to augment sound information for individuals with hearing loss. However, few studies have explored the use of multiple regions of the body sensitive to vibrotactile stimulation to convey discrete F0 information, important for music perception. This study explored whether mapping of multiple finger patterns associated with musical notes can be learned quickly and transferred to discriminate vocoded auditory stimuli. Each of eight musical diatonic scale notes were associated with one of unique finger digits 2-5 patterns in the dominant hand, where pneumatic tactile stimulation apparatus were attached. The study consisted of a pre and post-test with a learning phase in-between. During the learning phase, normal-hearing participants had to identify common nursery song melodies presented with simultaneous auditory-tactile stimulus for about 10 min, using non-vocoded (original) audio. Pre- and post-tests examined stimulus discrimination for 4 conditions: original audio + tactile, tactile only, vocoded audio only, and vocoded audio + tactile. The audio vocoder used cochlear implant 4 channel simulation. Our results demonstrated audio-tactile learning improved participant’s performance on the vocoded audio + tactile tasks. The tactile only condition also significantly improved, indicating the rapid learning of the audio-tactile mapping and its effective transfer.
An “asset” rather than “deficit” view of second-language (L2) speech
Authors: Bradlow Ann
Published: November 2022

This talk will present the rationale and empirical foundation for an “asset-” rather than “deficit-based” framework for understanding bilingual speech communication. In this framework, first-language (L1) and second-language (L2) speech are viewed as distinct speech styles each of which is shaped by four interacting sources of influence: (1) the individual talker’s vocal tract and ideolectal speech patterns (“trait” characteristics), (2) the sound structure of the language being spoken (“structural” characteristics), (3) the sound structure of other language(s), if any, in the talker’s repertoire (“repertoire” characteristics), and (4) general patterns of dominant versus non-dominant language function (“mode” characteristics). This “Trait-Structure-Repertoire-Mode” perspective contrasts with “deficit” models of the L1-L2 relationship in which metaphors of vectors (L1 source to L2 target) or filters (L1 filter for L2 production and processing) set up a hierarchy with L1 and L2 as “standard” and “deviant,” respectively. While still acknowledging L1 advantages in communication speed, accuracy, and ease, this perspective emphasizes the confluence of language-general properties (Trait and Mode) and language-specific properties (Structure and Repertoire) for speech production and perception by bilinguals in both/all of their languages.
Bilingualism, brain and development: A neuroemergentist perspective
Authors: Hernandez Arturo
Published: November 2022

Neuroemergentism, (NM) is a novel framework which has sought to consider language development as involving the organization and reorganization of cognition and its underlying neural substrate. Work to support this framework comes from studies of language and cognitive development. In this talk, I will focus on two separate levels, the sensorimotor plasticity needed to adjust to new input and the cognitive flexibility needed to select between these competing sources of information. This talk will discuss both these levels with regard to the neurocognitive adaptations seen in bilinguals. This will include structural brain differences in monolinguals and bilinguals that vary in the age of second language acquisition. In the second part, of the talk work that has focused on the cognitive flexibility will be presented. This will focus on the adaptations of the basal ganglia and frontostriatal tracts as a gating mechanism crucial for selecting the correct motor response. This includes newer work which links genes associated with dopamine to cognitive and language flexibility in bilinguals. The ways in which sensorimotor plasticity and cognitive flexibility represent accurate but incomplete conceptualizations of the competitive processes involved in language and cognitive processing will be discussed. The talk will conclude with potential future directions using an NM framework.
Non-native speech sound learning as a window to individual differences in the neural encoding of speech
Authors: Myers Emily
Published: November 2022

Non-native speech sound learning in adulthood is a skill marked by enormous individual differences, especially when compared to acquisition of speech sounds in childhood. This has led to the proposal that adult speech sound acquisition might be achieved through different mechanisms (or relying on fundamentally altered neural circuitry) compared to sound learning in infancy and childhood. One possibility we explore in a recent line of work is that individual differences in non-native speech learning are attributable to differences in the structure of brain areas responsible for processing speech, especially the transverse temporal gyrus. Of interest, the morphology of these same regions also predicts individual differences in native language speech perception, suggesting that sound acquisition (whether in childhood or adulthood) is limited by (likely innate) differences in neural architecture supporting sound processing. However, evidence that the best non-native perceivers are also the most finely-tuned native-sound perceivers is limited. Taken together, these results suggest that differences in brain structure are a soft constraint on the precision of acoustic-phonetic encoding, but that native language speech category structure is not the explanation for the difficulty of non-native sound learning.
Neural and cognitive mechanisms of accented speech processing: the role of speaker identity and listener experience
Authors: van Hell Janet , Grey Sarah , Abdollahi Fatemeh
Published: November 2022

Current everyday communication is a linguistic melting pot. Many learners of English as a second language have a nonnative accent when speaking English. We are also likely to interact with people from different language backgrounds, whose accent may be similar or different from one’s own accent. Although behavioral measures indicate that listeners adapt quickly to nonnative-accented speech, neurocognitive studies have shown distinct neural mechanisms in processing nonnative-accented sentences relative to native-accented sentences. I will present recent behavioral and EEG/ERP experiments that studied how speaker identity and listener experience affect the comprehension of nonnative- and native-accented sentences. Specifically, we studied how listeners’ experience with nonnative-accented speech modulates accented speech comprehension by testing different listeners (young and older adults with little experience with nonnative-accented speech, listeners immersed in nonnative-accented speech, and bilingual (nonnative-accented) listeners). We also examined how faces cuing the speaker’s ethnicity create language expectations, and how these biases impact the neural and cognitive mechanisms associated with the comprehension of nonnative- and native-accented sentences. Implications of the findings will be discussed by integrating neurocognitive theories of language comprehension with linguistic theories on the role of socio-indexical cues in speech comprehension.
The effects of higher higher-order dispersion on pulse propagation
Authors: Cohen Leon
Published: November 2022

We give explicit formulas for the propagation of a pulse in a dispersive medium governed by a general dispersion relation. In particular, we consider the mean and standard deviation of a propagating pulse and relate them to the parameters of the initial pulse and the dispersion relation. If the dispersion relation is expanded in a Taylor series, higher-order dispersion is when there are terms that are higher than quadratic. We show the effects of the higher-order dispersion on the propagation of the pulse's mean, standard deviation, and contraction/expansion time. Explicit examples will be given.
Instantaneous frequency: Definitions, interpretations and misconceptions
Authors: Loughlin Patrick
Published: November 2022

Due to the waveguide nature of the ocean surface and bottom, sounds propagating in shallow water can undergo frequency-dependent distortion (specifically, dispersion). This distortion manifests as changes in the instantaneous frequency of the sound, among other attributes. The most common approach for calculating the instantaneous frequency is via the analytic signal, developed by Gabor in the 1940s. Yet, many other definitions of instantaneous frequency have been given, before and since, resulting in a multitude of different answers for a given signal. What, then, is “the instantaneous frequency” of a signal, and what exactly is it a measure of? How are we to choose a particular method? A related question is, given a method, how do we determine whether or not it is a “good” method? We discuss these challenges and the history of the problem; physical constraints that have been proposed in attempts to uniquely define the instantaneous frequency; some common misconceptions; and the intriguing interpretation of instantaneous frequency as the “average frequency at each time” that arises from time-frequency distribution theory.
Inference of both source and seabed characteristics from broadband signals on the New England continental slope
Authors: Knobles David P. , Wilson Preston S. , McNeese Andrew R. , Hodgkiss William , Neilsen Tracianne B.
Published: November 2022

In this study the characteristics of the modal dispersion of acoustic waves in littoral ocean environments are utilized to infer both source properties (range, depth, speed, and source level) and geoacoustic properties of the seabed. An analysis is made of broadband acoustic data (10–4500 Hz) taken during 2021–2022 on the New England continental slope over water depths from 200 to 500 m. The acoustic data are generated by both moving broadband sources and explosive sources over range scales of 1–30 km. Such range scales can reveal the nature of the modal dispersion. Conductivity, Temperature, and Depth (CTD) and Expendable Bathythermographs (XBTs) measurements provide a sparse sampling of the temporal and spatial variability of the ocean during the acoustic measurements. Along with bathymetry measurements the sound speed profiles derived from the CTDs and XBTs provide prior information for an inverse problem from which insight can be obtained on the effects of the seabed on the dispersion of broadband propagation.
A physics-informed machine learning based dispersion curve estimation for non-homogeneous media
Authors: Tetali Harsha Vardhan , Harley Joel
Published: November 2022

Modern machine learning has been on the rise in many scientific domains, such as acoustics. Many scientific problems face challenges with limited data, which prevent the use of the many powerful machine learning strategies. In response, the physics of wave-propagation can be exploited to reduce the amount of data necessary and improve performance of machine learning techniques. Based on this need, we present a physics-informed machine learning framework, known as wave-informed regression, to extract dispersion curves from a guided wave wavefield data from non-homogeneous media. Wave-informed regression blends matrix factorization with known wave-physics by borrowing results from optimization theory. We briefly derive the algorithm and discuss a signal processing-based interpretability aspect of it, which aids in extracting dispersion curves for non-homogenous media. We show our results on a non-homogeneous media, where the dispersion curves change as a function of space. We demonstrate our ability to use wave-informed regression to extract spatially local dispersion curves.
Dispersion of broadband signals in the Seabed Characterization Experiment-2022
Authors: Potty Gopu R. , Miller James H. , Moss Lindsey J. , McNeese Andrew R. , Wilson Preston S. , Lin Ying-Tsong , Dall'Osto David R.
Published: November 2022

Broadband sources such as SUS charges and Rupture Induced, Underwater Sound Sources (RIUSS) were deployed in the New England Mud Patch in support of the 2022 Seabed Characterization Experiment. Data measured on the Ocean Bottom Recorders (OBX) and hydrophones will be discussed. Five OBXs were deployed on the seabed and four hydrophones were configured as a tetrahedral array on the bottom mounted Geosled. The OBXs measured three components of particle velocities and acoustic pressure. The spatial variability in the dispersion of broadband signals observed in the pressure and particle velocity data will be discussed. Presence of Scholte waves on the OBX data will be explored using the random decrement technique. Results will be compared with modeling using the seismo-acoustic propagation code (OASES). Outputs of preliminary inversions will be compared with core data collected as part of the experiment. [Work Supported by Office of Naval Research.]
Ultrasound image formation in the deep learning age
Authors: Bell Muyinatu
Published: November 2022

The success of diagnostic and interventional medical procedures is deeply rooted in the ability of modern imaging systems to deliver clear and interpretable information. After raw sensor data is received by ultrasound and photoacoustic imaging systems in particular, the beamforming process is often the first line of software defense against poor quality images. Yet, with today’s state-of-the-art beamformers, ultrasound and photoacoustic images remain challenged by channel noise, reflection artifacts, and acoustic clutter, which combine to complicate segmentation tasks and confuse overall image interpretation. These challenges exist because traditional beamforming and image formation steps are based on flawed assumptions in the presence of significant inter- and intrapatient variations.In this talk, I will introduce the PULSE Lab’s novel alternative to beamforming, which improves ultrasound and photoacoustic image quality by learning from the physics of sound wave propagation. We replace traditional beamforming steps with deep neural networks that only display segmented details, structures, and physical properties of interest. I will then transition to describing a new resource for the entire community to standardize and accelerate research at the intersection of ultrasound beamforming and deep learning. This resource includes the first internationally crowd-sourced database of raw ultrasound channel data and integrated beamforming and evaluation code (see https://cubdl.jhu.edu/ & https://pulselab.jhu.edu/ for more details).
Acoustic Signature: A focused ultrasound guidance technique with sub-millimeter accuracy
Authors: Manuel Thomas J. , Singh Aparna , Kusunose Jiro , Caskey Charles F.
Published: November 2022

Accurate targeting is paramount for focused ultrasound (FUS) procedures. Here we describe a method for targeting FUS dubbed acoustic signature, which uses acoustic feedback from a target’s unique reflection patterns to guide the transducer to a previously defined orientation. We demonstrate convergence to the desired target in a 3 degree of freedom (DOF) water tank scenario and a 5 DOF robotic arm scenario. We also tested the acoustic signature technique for targeting with a phantom skull on a 3 DOF motor stage and a 5 DOF manual stereotactic frame designed for transcranial FUS procedures in an MRI environment. In both the water tank and the robotic arm convergence tests, the method converges to the target. The convergence was sufficiently smooth for automated gradient descent. In the 3-DOF test, the net targeting error was 0.30 ± 0.27 mm (n = 10). In the stereotactic frame 5-DOF test, the targeting error was 2.11 ± 0.99 mm and 3.2 ± 2.2° (n = 10) summed rotational error. The accuracy of this technique is limited by the positioning apparatus. This method may enable precise and repeatable FUS targeting for therapies which require multiple FUS sessions at the same target.
Reconstruction of thermoacoustic emission sources from proton irradiation using numerical time reversal
Authors: Mast T. Douglas , Johnstone David A. , Dumoulin Charles L. , Lamba Michael A. , Patch Sarah K.
Published: November 2022

Dose delivery in proton beam therapy for cancer treatment can be mapped by analyzing thermoacoustic emissions measured by ultrasound arrays. Here, a method is presented for spatial mapping of thermoacoustic sources using numerical time reversal, simulating physical re-transmission of measured emissions into the medium. The spatial distribution of acoustic sources is shown to be approximated by the amplitude envelope of the time-reversed field, evaluated at the time of emission. Given calibration of the array sensitivity and knowledge of tissue properties, this approach approximately reconstructs the induced acoustic pressure, equal to the product of radiation dose, density, and Grueneisen parameter. Numerical time reversal is implemented using two models for array elements, as either ideal line sources or diffracting rectangular radiators. Demonstrated reconstructions employ previously reported measurements of thermoacoustic emissions from proton energy deposition in tissue-mimicking phantoms. For a phantom incorporating a bone layer, reconstructions account for the higher sound speed in bone. Spatial resolution of reconstructions, assessed by widths of reconstructed Bragg peaks, is improved in the array direction by incorporation of diffraction effects. In comparisons with corresponding Monte Carlo simulations, source distributions correspond well with simulated proton dose, while source localization with respect to room coordinates is improved by incorporating sound speed inhomogeneities.
Passive cavitation imaging in fuel injector nozzles
Authors: Gupta Ankush , McDonough Grace K. , Moreira Jennifer , Lau Jeremy , Doheny Victoria V. , Ryan Emily , Grace Sheryl M. , Holt R. Glynn
Published: November 2022

Modern fuel injection systems operate at high pressures and flow velocities. Injectors can be pressurized in excess of 10 MPa, resulting in fuel velocities on the order of hundreds of meters/second in the mm and sub-mm internal confines of a fuel injector. Subsequent ejection velocities at the nozzle yield characteristic atomization droplet size distributions and spread angles. Studies have shown or inferred the presence of cavitation in such fuel injectors, typically beneficially decreasing ejection droplet sizes while increasing the spray spreading angle. While beneficial for fuel atomization, it is known that bubble collapse near a solid surface produces a strong jet which impinges on the surface and causes erosion. In this study, Fourier based image reconstruction is used to perform Passive Cavitation Imaging (PCI) in laboratory nozzles to detect, characterize, and most importantly localize inertial cavitation. [Work funded by DOE.]
Simulating multiple scattering inside a population of nonlinearly oscillating microbubbles using the Iterative Nonlinear Contrast Source method
Authors: Matalliotakis Agisilaos , Verweij Martin D.
Published: November 2022

For several decades, microbubbles have been the primary choice for ultrasound contrast agents both for efficiency and safety reasons. To optimize their performance in various applications e.g. proton therapy, it is important to understand the dynamics of populations of nonlinearly oscillating microbubbles. Especially for high concentration clouds, multiple scattering can significantly influence the propagation of medical ultrasound. To numerically study the higher-order interaction between nonlinear microbubbles, we present a modified version of the Iterative Nonlinear Contrast Source (INCS) method. Based on a Neumann iterative scheme, the acoustic pressure is obtained by treating the nonlinearly scattering bubbles as individual contrast sources in a “linearized” background medium. In each iteration, the full nonlinear pressure field is updated by applying the 4D spatiotemporal convolution between the background Green’s function and the contrast sources obtained from the previous iteration. In this study, all microbubbles may exhibit an individual behavior. To accommodate this, in each iteration the solution of the Marmottant equation for each microbubble is obtained and used as the temporal signature of the respective contrast source. Using this scheme, each iteration adds an order of multiple scattering. The accuracy and the efficiency of INCS results will be demonstrated for monodisperse and polydisperse concentrations.
Power Doppler-based ultrasound detection of cavitation for burst wave lithotripsy
Authors: Maxwell Adam , Cunitz Bryan W. , Wang Yak-Nam , Hunter Christopher , Kim Ga Won , Totten Stephanie , Bailey Michael R. , Kreider Wayne
Published: November 2022

Burst wave lithotripsy (BWL) is a noninvasive method to fragment urinary stones with pulsed focused ultrasound. Cavitation activity produced by ultrasound pulses in BWL can cause multiple effects including stone fragmentation, acoustic shielding, and tissue injury. Monitoring cavitation activity and spatial extent is therefore important to evaluating these effects and determining parameters that maximize effectiveness and safety. In vivo experiments in a porcine model were conducted using a Verasonics ultrasound system to detect the onset and spatial extent of cavitation through synchronized power Doppler ultrasound imaging during 350-kHz BWL exposures to stones and kidney tissue. Kidneys (n = 15) were exposed in vivo to transcutaneous BWL at multiple pressure levels, and cavitation in tissue was found to be detected as an increase in the measured Doppler power by an average of 28.6 dB (range 11–51 dB) over the background. Cavitation occurred at average levels between 5.8 and 8.0 MPa peak negative pressure, depending on targeting location, stone presence, and exposure parameters. Cavitation presence further correlated with gross observation of injury. These studies demonstrate suggest filtered power Doppler imaging can sensitively detect presence of sustained cavitation during burst wave lithotripsy exposures. [Work supported by NIDDK K01 DK104854 and P01 DK043881.]
Piezoelectric finite-difference time-domain simulations of piezoelectric signal generated in cancellous bone by ultrasound irradiation
Authors: Hosokawa Atsushi
Published: November 2022

Bone formation can be driven by mechanical loads applied to the bone. By taking advantage of this mechanism, the accelerated healing of bone fracture using low-intensity pulsed ultrasound (LIPUS) has been medically practiced. Bone can behave as a piezoelectric material, and the piezoelectric effects are considered to accompany the bone formation. However, the piezoelectric properties in bone, particularly in cancellous bone with a porous structure, at ultrasound frequencies are too complex to easily clarify. In such a case, numerical simulations can be helpful because they enable visualization in the "black box." Numerical simulations by an elastic finite-difference time-domain (FDTD) method have been widely performed to investigate ultrasound behaviors in bone. In this study, the elastic FDTD method with piezoelectric constitutive equations (PE-FDTD method) was used to simulate the piezoelectric signals generated in water-saturated cancellous bone by ultrasound irradiation. The cubic cancellous bone model was reconstructed from the x-ray microtomographic image. The piezoelectric signal waveforms when an ultrasound burst wave was irradiated in three orthogonal directions were calculated, together with the ultrasound signal waveforms propagated through cancellous bone. From the calculated results, the effect of the trabecular orientation was investigated.
Viscoelastic transcranial wave propagation modeling for neuronavigated focused ultrasound procedures in humans
Authors: Pichardo Samuel
Published: November 2022

Transcranial focused ultrasound (FUS) has gained significant attention as a non-invasive therapeutic technique that can reach both cortical and subcortical targets in the human brain. However, the skull barrier distorts the ultrasound beam and introduces significant losses that need to be accounted for. In this talk, I will present our efforts to develop high precise transcranial ultrasound modeling based on the open-source viscoelastic wave propagation solver BabelViscoFDTD and its application in neuronavigated procedures for FUS-based neuromodulation. The viscoelastic wave equation is expressed in isotropic stress tensors and displacement vectors, and their nodes are placed in a staggered grid arrangement. The solver uses a Cartesian O(4)-space O(2)-time FDTD scheme. A narrow-band quality factor models attenuation. A reduction of staircase artifacts can be enabled using a superposition operator. BabelViscoFDTD is optimized for multiple computing GPU and CPU backends (CUDA, OpenCL, Metal, and X86-64) and includes GPU-accelerated solvers of the Rayleigh-Sommerfeld equation and Bio-Heat thermal equations. We adapted the viscoelastic and thermal solvers to neuronavigate two FUS devices: A 128-element concaved array operable at 250 kHz and 700 kHz and a 4-ring concaved array operable at 500 kHz. The high degree of optimization of the solvers allow that numerical procedures (neuronavigation and modeling) can be performed in an Apple M1 Max (64 GB RAM) laptop computer.