bluuebunny/crossref_metadata_2025 huggingface dataset:
Digging into sentence intelligibility: Interactions with talker
Authors: Tucker Benjamin V. , Kelley Matthew C. , Oganyan Marina , Wright Richard A.
Published: November 2022

An implicit feature found in studies of intelligibility and perception is the assumption that noise masks all spoken-sentence stimuli equivalently regardless of the stimulus-talker. For example, when using controlled and normed sentences, such as the IEEE Harvard set, the mean intelligibility across talkers should be affected by masker-noise equivalently. In other words, any particular sentence spoken by one talker should be equivalently intelligible to when it is spoken by another talker using the same style and rate. However, previous studies have shown that there is significant intelligibility variation between talkers in controlled stimuli. Therefore, we predict talker-masker interactions in the IEEE stimuli. We investigated the UAW speech intelligibility dataset which contains typed responses from over 900 native listeners of English to over 604 sentences from the UWNU IEEE sentence corpus presented in three signal-to-noise ratios ( + 2, 0, −2 dB). We calculated the Levenshtein Distance for the listeners’ transcriptions of the sentences. We find that different talkers have different intrinsic intelligibility even when reading the same set of sentences. Moreover, we find an interaction with SNR level and individual talker intelligibility. The present results suggest that individual talker effects in speech stimuli may influence the outcomes of perception and intelligibility studies.
Speaking rate normalization with and without segregation of simultaneous context sentences
Authors: Stephens Dawson , King Caleb J. , Shorey Anya E. , Stilp Christian E.
Published: November 2022

Speech perception is shaped by acoustic properties of earlier sounds influencing recognition of later speech sounds. For example, when a context sentence is spoken at a faster rate, the following target word (varying from “deer” to “tier”) is perceived as “tier” (longer VOT) more often; when a slower context sentence is spoken, the following target word is perceived as “deer” (shorter VOT) more often. This is known as a temporal contrast effect (TCE, a.k.a. speaking rate normalization). Recently, Bosker, Sjerps, and Reinisch (2020 Scientific Reports) concluded that selective attention (to one of two simultaneous talkers) had no impact on TCEs. However, their paradigm was not an ideal test of this question; the voices heard were different talkers presented to each ear, and thus relatively easy to perceptually separate. Here, on each trial, the same talker spoke one sentence to both ears (no segregation), two sentences simultaneously to both ears (poor segregation), or a different sentence to each ear (easier segregation). Fast or slow context sentences preceded target words varying from “deer” to “tier.” TCE magnitudes were similar across all presentation modes. Results are consistent with the claims set forth by Bosker et al. – TCEs are automatic and low-level, not modulated by selective attention.
Adapting to talkers in speech perception: Balancing generalization and individuation
Authors: Chiu Samantha , McMurray Bob , Toscano Joseph C. , Toscano Cheyenne M.
Published: November 2022

Listeners can account for systematic variability between talkers, which is learned over exposure to multiple talkers. Previous research suggests that listeners can both generalize prior knowledge of phoneme categories from a familiar to a novel talker (Eisner & McQueen, 2005; Kraljic & Samuel, 2006, 2007) and individuate talkers, preventing generalization (Luthra, Mechtenberg, & Myers, 2021; Tamminga, Wilder, Lai, & Wade, 2020). It is unclear how listeners balance these competing demands. Participants (n = 160) learned two novel talkers (one male and one female voice) with a unique voice onset time (VOT) boundary across two days. On each day, participants were passively exposed to a bimodal distribution of VOTs from one talker, then tested on a second talker (uniform distribution). Day 1 assessed how listeners generalize to a novel talker while Day 2 assessed how the talker that was learned on Day 1 is individuated from the new talker. We found evidence for generalization after Day 1 but little evidence of learning after learning both talkers on Day 2. Two follow-up experiments using interleaved designs and supervised learning also showed little evidence for individuation. This suggests that listeners are likely accounting for variability by shifting their VOT boundary to match current input.
Audio (vector) algebra: Vector space operations on neural audio embeddings
Authors: Hawley Scott H. , Evans Zach , Baldridge Joe
Published: November 2022

Ever since the work of Castellon, Donahue, and Liang (ISMIR 2021) showed that latent space “embedding” representations encoded by OpenAI's Jukebox model contain semantically meaningful information about the music, many have wondered whether such embeddings support vector relations akin to the famous “king—man + woman = queen” result seen in word vector embeddings. Such an “audio (vector) algebra” would provide a way to perform operations on the audio by displacing the embeddings in certain directions, and then decoding them to new sounds. The nonlinear aspects of the encoding process suggest that this may not be possible in general, however, for certain kinds of operations in finite regions of embedding spaces, such embedding vector transformations may indeed have musically relevant counterparts. In this talk we investigate the feasibility of such schemes for the cases of mixing and audio effects.
Digital models of analog circuits for musical audio production: A review of techniques and library for automated circuit solving
Authors: Tarr Eric
Published: November 2022

In music production, many recording and mixing engineers prefer to use analog equipment as a matter of perceptual preference. Digital models of analog circuits have the potential to achieve similar perceptual qualities as hardware without the drawbacks of cost, maintenance, and availability. Many different techniques of system modeling are used in music production software, ranging on a spectrum from “black-box modeling” to “white-box modeling.” In black-box modeling, the analog system is modeled as a processing block which maps an input signal to an output signal. Examples include the linear impulse response, adaptive filters, Volterra series, and Weiner-Hammerstein models. In white-box modeling, each individual component of the analog circuit is modeled as part of the overall system. Examples include wave digital filters, state-space modeling, and modified nodal analysis. Various other techniques exist on the spectrum between these two types, using some combination of each. One example is Virtual Analog Filtering based on the Topology Preserving Transform. Machine Learning techniques have also had an important role in advancing the accuracy of digital modeling. Lastly, the “Point to Point Library,” developed by the author, will be demonstrated. This MATLAB and C + + library performs automated circuit solving for modeling audio effects.
Realism analysis of synthesized healthcare sound environments
Authors: okcu selen
Published: November 2022

The acoustic qualities of healthcare sound environments can have significant influences on care providers’ ability to conduct critical sound tasks. Healthcare professionals constantly listen to the aural cues (e.g., alarms) and make critical decisions based on them. This study aims to assess the reliability of an open-source acoustical simulation tool in rendering healthcare providers’ auditory experience to enable the development of effective healthcare sound environments. The Pachyderm is developed as an open-source acoustical modeling and simulation plug-in for the Rhinoceros 3D-modeling platform commonly used by designers. The plug-in can compute various room acoustics metrics and generate auralizations by convolving anechoic recordings with the predicted acoustic signature of the architectural settings. While reliable predicted acoustic metrics are critical for iterative room-acoustics design studies, high fidelity auralizations can enable acoustic evaluations mainly based on critical listening and encourage collaboration between acoustical consultants, care providers and designers. The study introduces the findings of acoustic assessments including simulations and field measurements conducted in a new 14-bed adult medical-surgical inpatient unit at Milton S. Hershey Medical Center. The effectiveness is evaluated based on the deviation between the predicted and measured objective measures, and perceived differences between the auralizations and audio recordings assessed via listening tests.
Acoustics for in-process melt pool monitoring during metal additive manufacturing
Authors: Kube Christopher M.
Published: November 2022

Intrinsic to most metal additive manufacturing (AM) processes are melt pools generated from directed energy sources like lasers. Melt pools are critical as they function to join powder layers to previous layers during the process. Their criticality extends deeper as most porosity in AM parts stems from melt pool behavior while melt pool solidification dictates the parts’ microstructure. Significant breakthroughs in metal AM are severely hindered by the lack of access to experimental tools to study melt pools and modeling that do not fully capture the complex physics. Thus, melt pool related defects are often difficult to predict in occurrence and location while determining optimal process parameters to eliminate defects is extremely challenging and costly. Furthermore, the many exciting opportunities such as realizing new AM alloys, developing gradient materials/structure, and tailoring microstructure to intended applications are possible only with further understanding of melt pool behavior. With these clear needs, in-process acoustics have been proposed as plausible experimental tools for studying melt pool behavior. This presentation will provide an overview of the current activity in this area in addition to the specific needs the acoustics community can potentially address.
The National Institute for Occupational Safety and Health recommended exposure level for noise needs to be revised downwards
Authors: Fink Daniel
Published: November 2022

Noise-induced hearing loss (NIHL) is caused by cumulative occupational and non-occupational noise exposure. The National Institute for Occupational Safety and Health (NIOSH) developed recommendations for occupational noise exposure in 1972, revised in 1998. Fifty years after the NIOSH 85 dBA recommended exposure level (REL) was first published, it needs to be revised downwards. In its calculations, NIOSH assumed that workers have quiet (<60 dBA) when not at work, something no longer true. Everyday public noise exposure now exceeds the Environmental Protection Agency's safe noise level, a time-weighted average of 70 dB for 24 hours, with multiple studies reporting average exposures near 75 dBA. Also, NIOSH calculations were based on occupational studies of material hearing loss measured by limited frequency pure tone audiometry, an insensitive measure of noise-induced auditory damage. Modern audiology techniques include extended range audiometry, speech in noise testing, diffusion product otoacoustic emissions testing, and questions about tinnitus and hyperacusis. Doing the needed research to support downward REL revision, detecting auditory damage in noise-exposed workers with these newer techniques, is a daunting task, but this is necessary both to protect workers and because the NIOSH REL forms the basis for the world's recommendations for non-occupational noise exposure.
Measuring the effect of ground impedance on the vector field, both in air and underwater
Authors: Dall'Osto David R. , Dahl Peter H. , Waite Jim
Published: November 2022

One direct advantage to characterizing the acoustic field with a vector sensor is the ability to measure both components of acoustic energy, potential (pressure) and kinetic (particle velocity). While it is well known that the kinetic energy exceeds potential in the near-field of a source, equivalent and opposite imbalances are prevalent in the far-field due to propagation effects. For example, at normal incidence the field exhibits a distinct frequency dependent relationship that depends explicitly on the impedance of the ground reflector, including any internal reflections from sediment layers. In this paper, we examine the measured vector field, both in-air and underwater, with a specific focus the energy balance when a source is directly overhead. While the construction of a neutrally buoyant volume for use in dense media (such as water) is fairly straightforward, the application to airborne acoustics requires extremely lightweight materials. Airborne measurements are provided by an Accelerometer-based Intensity Vector Sensor (AIVS) system, which is constructed from a lightweight MEMS accelerometer and microphone embedded in a spherical, expanded polystyrene (EPS) foam volume.
Individual factors that impact noise tolerance
Authors: Oeding Kristi , Davies-Venn Evelyn , Nelson Peggy
Published: November 2022

One of the most common complaints of patients wearing hearing aids is difficulty hearing speech in noise. Limited information is available on how to program speech in noise programs as fitting formulas are based on quiet environments. In order to understand what settings could optimize programs in background noise, it is important to determine what objective and subjective factors impact speech understanding in noise. This study sought to evaluate what individual factors (personality, working memory, noise tolerance, and speech in noise abilities) might impact person’s tolerance in background noise. Data was collected remotely using questionnaires and equipment that was dropped off at the participant's home due to covid restrictions at the time. A principal component analysis was used to determine clusters of patients based on the examined factors. The goal of finding group factors will be used to determine the best settings to increase a hearing aid user’s tolerance for background noise so they can wear their hearing aids in these environments and hear speech better. Benefits and disadvantages of at home testing will also be discussed.
Middle-ear muscle reflex: Sensitivity and reliability of thresholds and amplitude-intensity functions in normal-hearing adults across measurement systems
Authors: Bochat Sarah L. , Higgins Nathan C. , Goodman Shawn S. , Eddins David A. , Eddins Ann C.
Published: November 2022

Standard clinical middle-ear muscle reflexes (MEMRs) are typically measured as a change in admittance for a single, 226-Hz probe tone in the presence of an eliciting stimulus. Alternatively, wideband MEMRs are measured as a change in reflectance for a wideband click probe in the presence of an elicitor. This study evaluated test-retest measures of MEMR thresholds and amplitude-intensity (A-I) functions across four measurement systems based on differences in sensitivity (i.e., thresholds, A-I slopes) and reliability. Ten normal-hearing adults participated in two sessions. MEMR thresholds and A-I functions were measured using two clinical systems (GSI, Titan) with two elicitors (2 kHz, broadband noise-BBN), and two wideband systems (Titan Research module, Custom Etymotic-based system). The 2-kHz elicitor yielded the highest thresholds overall. BBN elicitors produced similar thresholds across clinical and wideband systems. The broadband elicitor with the clinical systems produced the steepest A-I slopes, and the slopes were steeper overall for clinical versus wideband systems. In most conditions, no significant test-retest differences were observed for thresholds or AI-functions, but intraclass correlations were highest for the clinical system measures. MEMR measures made with current clinical systems using BBN elicitors may optimize sensitivity, reliability, and overall diagnostic value of such measures.
The possible range of interaural cross correlation after cochlear implant processing
Authors: BK Prajna , Bottalico Pasquale , Aronoff Justin M.
Published: November 2022

Normal hearing listeners rely on their binaural auditory system to combine signals from both ears into single auditory objects, which aids source segregation and sound localization. The ability to combine signals from the two ears is influenced by interaural symmetry - the similarity of the place of stimulation along the left and right cochlea—and the interaural cross-correlation (ICC) of the signal, calculated as the peak correlation between the signal for the two ears across unilateral temporal offsets. The ability of bilateral cochlear implant (CI) users to combine signals from the two ears can be worse than that of NH listeners. This is partly attributed to decreases in interaural symmetry related to factors such as differences in electrode array insertion depth. A secondary effect of interaural asymmetry is that it can result in reduced ICC at interaurally symmetric locations, mediated by aspects of CI processing. This study aims to investigate how CI processing and interaural asymmetry affect the ICC available to CI users for interaurally symmetric locations, using electrodograms recorded from a CI processor placed on a Knowles Electronics Manikin for Acoustic Research (KEMAR). Inferences on how ICC is altered with interaural asymmetry for CI users will be discussed.
Measuring decay time in non-diffuse rooms
Authors: van der Harten Arthur W. , Azevedo Matthew
Published: November 2022

Measurements in non-diffuse rooms present challenges in determining decay time. A room with a severe flutter echo may exhibit a double slope decay without the incorporation of a coupled chamber. The measured decay time may differ greatly depending on the software used to measure, the choice of Schroeder integral sampling range, and how noise correction is implemented. A standardized approach to characterizing decay time under non-diffuse conditions is needed. In this talk, the authors discuss possible methods for determining the optimal noise correction and sampling of the Schroeder integral, including varying the IR truncation and sampling start and stop range. Computational optimization methods are employed to objectively determine the most reasonable settings for interpreting a particular impulse response.
Spatial release from masking in anechoic and reverberant environments
Authors: Hintz Drake A. , Wang Lily M. , Peng Z. Ellen
Published: November 2022

Listening with both ears provides children with access to binaural and monaural cues that are helpful for understanding speech in competing babbles. Specifically, when the target and masker are spatially separated, children can gain an intelligibility benefit which is known as spatial release from masking (SRM). Recent work [Peng et al., 2021 JASA] suggested that school-age children demonstrated immature SRM using binaural cues that are distorted by reverberation. In this follow-up study, we further investigate the effect of reverberant distortion on individual auditory spatial cues, namely binaural and monaural head shadow cues. We compare SRM between adults and school-age children with typical hearing using the novel measure of minimum angle of separation (MAS) between target and masker, for which individual achieves a 20% intelligibility gain, in both virtually simulated anechoic and reverberant environments. MAS was measured in both binaural and monaural hearing conditions, as well asymmetric versus asymmetric masker displacement to probe access to various auditory cues of interest. Preliminary results show that adults demonstrate similar SRM in anechoic and in reverberation of T60 = ∼0.6 s, but better (smaller MAS) when additional spatial cues become available. Reverberation effect on children’s SRM will be discussed. [Work supported by NIH-NIDCD.]
Improved characterization of ambient sound levels in a coastal environment via use of an unmanned Wave Glider
Authors: Lafrate Joseph , Dossot Georges , Watwood Stephanie , Reyier Eric , Ahr Bonnie
Published: November 2022

In this project, we use an unmanned Liquid Robotics SV3 wave glider as a tool for basic research studying ambient acoustics in shallower, coastal waters off the coast of East-Central Florida. The primary objective is to characterize sound levels in varying conditions via collection of high-resolution environmental data. The SV3 is used to systematically characterize the acoustic environment in coastal waters, while simultaneously measuring oceanographic parameters such as wind speed, wind direction, and wave height. Quantifying the influence of these fundamental oceanographic influences on shallow water acoustics will provide improved characterization of surface noise and comparison with traditional ambient noise spectra. Ambient noise spectra will be presented for various sea states and wind scenarios, as measured at 25 foot depth using a towfish attached to the SV3. Some of these measurements are also compared to fixed station bottom recordings. Finally, this effort also includes characterization of unique sources of biological sounds recorded by the SV3, including not previously documented loud fish chorusing in this region.
Adaptive beamformer with echo statistics
Authors: Hasegawa Hideyuki , Akamatsu Takumi , Omura Masaaki , Nagaoka Ryo
Published: November 2022

Delay-and-sum (DAS) beamforming is commonly used in commercial scanners and computationally efficient for real-time imaging. However, the ability to suppress off-axis signals is limited. A minimum variance (MV) beamformer realizes a superior performance in suppression of off-axis signals and improves lateral resolution significantly. On the other hand, MV degrades the contrast-to-noise ratio (CNR) compared to DAS because it alters speckle statistics. In this study, we developed a method for improvement of CNR in MV beamforming by evaluating envelope statistics of echo signals. It is well known that the envelope statistic of speckle echoes from a random medium obeys the Rayleigh distribution. The echo envelope statistics were evaluated using the shape parameter of the Nakagami distribution. The proposed beamformer is worked as DAS for speckle echoes and MV for non-speckle echoes by referring to the Nakagami shape parameter. In the phantom experiment, the lateral resolution of MV was 0.18 mm, which was significantly better than 0.53 mm obtained by DAS. However, CNR was degraded from 6.73 dB to 4.05 dB by MV. The proposed beamformer realized a lateral resolution of 0.25 mm, which was significantly better than DAS, with a CNR value of 6.03 dB, which was comparable to DAS.
On the use of denoing algorithms for ultrasound beamforming
Authors: Goudarzi Sobhan , Basarab Adrian , Rivaz Hassan
Published: November 2022

Beamforming in receive, whose objective is to estimate an image from raw RF data acquired by the probe piezoelectric elements, plays a crucial role in ultrasound imaging. The standard method, called delay and sum (DAS) and implemented in most of the commercial scanners, consists in coherently summing the RF signals, providing the backprojection solution of the inverse problem of beamforming. Despite real-time properties, DAS results into images with limited spatial resolution and contrast. The literature of ultrasound beamforming is rich and mainly consists in alternatives to DAS based on non-adaptive or adaptive (e.g., minimum variance, coherence factor) methods or image reconstruction algorithms in the Fourier domain. Furthermore, inverse problem formulations have been shown to be well-adapted to ultrasound beamforming. They consist in minimizing a cost function formed by two terms: a data fidelity term modelling the acquisition setup, and a regularization term. The choice of the latter is not straightforward in ultrasound imaging, mainly because of the need to conserve statistical properties of the speckle. In this paper, denoising algorithms are shown to be good regularizers for ultrasound beamforming, providing a good performance in spatial resolution and contrast gain, without deteriorating the quality of the speckle texture.
Correlation-based ultrasound imaging: A diagnostic enabler
Authors: Bilodeau Maxime , Krpic Tamara , Quaegebeur Nicolas , Masson Patrice
Published: November 2022

Correlation-Based (CB) ultrasound imaging relies on the correlation of measured signals with signals from a simulated or measured database. The CB imaging algorithm Excitelet has demonstrated better ultrasound image quality in Non-Destructive Testing (NDT) applications. In medical applications, ultrasound imaging is characterized by weak image dynamics when compared with Magnetic Resonance Imaging (MRI) or Computed Tomography (CT). However, portable, low-cost, and reliable diagnostic tools based on ultrasound imaging could help reducing the delays between patient assessment and treatment. In order to see more ultrasound-based diagnostics, collective research efforts are still required.Recent work on the use of the CB framework in medical imaging has enabled new diagnostic modalities. Indeed, CB imaging extends the field of view due to the near perfect compensation of the intrinsic properties of the transducers (directivity, dynamics, imperfections, lenses). New automated tools allow using a measured signal database, as opposed to simulated database previously required in CB imaging. Due to its frequency formulation, a realistic signal database enables local acoustical impedance estimation through the reconstruction of the reflectors/diffusers local phase. It is herein proposed to overlay this color-coded phase information, as typically done in Doppler imaging, to enrich the ultrasound image, and facilitate image interpretation.
Optical-acoustics source analysis of supersonic jet noise reduction using micro vortex generators
Authors: Saleem Mohammad , Rodriguez Omar L. , Karnam Aatresh , Gutmark Ephraim , Liu Junhui
Published: November 2022

A new supersonic jet noise reduction technology has been developed using Micro Vortex Generators (MVGs) by the collaboration between the University of Cincinnati and the Naval Research Laboratory. MVGs are used on model scale nozzles that are representative of GE F404 engine nozzles. Noise reductions up to −10 dB have been observed in both laboratory measurements and LES simulations at conditions related to take off in the overexpanded regime. Analysis of the acoustic field and flow field using Schlieren visualization reveal the noise reduction mechanisms associated with MVGs. Direct visualization of the changes in shock cell spacing, Large Coherent Structures (LCS) formation, and their convective velocity are identified and those changes modify the downstream propagating hydrodynamic waves and the upstream propagating acoustics waves. Spectral Proper Orthogonal Decomposition (SPOD) is utilized to examine the flow sources at frequencies associated with the noise components observed in the acoustic spectra to explain the noise reduction mechanisms of MVGs.
Light, sounds, and magnetism: Enhanced image-guided adoptive cell therapy using T cells tagged with multifunctional nanoparticles
Authors: Kubelick Kelsey , Kim Myeongsoo , Kim Jinhwan , Lee Jeungyoon , Jhunjhunwala Anamik , Yu Anthony , Emelianov Stanislav
Published: November 2022

Methods to noninvasively increase and assess T cell infiltration are critical for success of adoptive cell therapy (ACT) of solid tumors where only a small fraction of adoptive T cells typically accumulates at the target. We developed an approach based on photoacoustic (PA) and ultrasound (US) imaging to visualize magnetic field driven accumulation of T cells tagged with photo-magnetic nanoparticles (PMNPs). Specifically, Au@Fe3O4 shell-core PMNPs (200 nm diameter), absorbing at 1064 nm wavelength, were synthesized and characterized using a UV-Vis-NIR spectrophotometry, dynamic light scattering (DLS), and transmission electron microscopy (TEM). Ovalbumin (OVA)-targeted PMNP-tagged OT1 murine primary T cells were injected intravenously into OVA-expressing tumor-bearing C57BL/6 mice. US/PA imaging (20 MHz, 1064 nm and 680–970 nm, Vevo LAZR, Visualsonics Inc.) of the primary tumor and regional lymph nodes showed accumulation of PMNP-tagged T cells. Our results indicate feasibility of the T cell tagging with PMNPs and magnetic delivery of adoptive PMNP-tagged T cells using US/PA imaging thus providing critical imaging feedback to improve the adoptive T cell therapy of solid tumors. Overall, our studies show that a synergistic combination of US/PA imaging and magnetic delivery of nanoparticle (NP)-tagged adoptive T cells can expedite development, translation, and expansion of ACT.
Opto-mechanical material characterization via dual-geometry Brillouin confocal microscopy
Authors: Fiore Antonio , Scarcelli Giuliano
Published: November 2022

Brillouin scattering is a light-matter interaction that induces a frequency shift in the scattered photons. Such shift directly depends on the optical and mechanical properties of the material itself. In the last decade, Brillouin frequency shift has become a reliable proxy for mechanical stiffness in biological samples such as cells and tissues, with the subsequent development of Brillouin confocal microscopy; however, such correlation does not apply to samples with high degree of inhomogeneity. Recently, we showed that a dual geometry Brillouin microscopy enables the direct measurement of refractive index and speed of sound. We now report an improved dual-geometry microscopy technique that allows measurement of optoacoustical properties within a confocal volume. This goal has been achieved through the measurement of frequency, linewidth, and intensity of Brillouin components of the scattered light spectrum. Finally, we proved our three-dimensional imaging capability by mapping, with micron-scale resolution, the refractive index, density, and viscoelastic properties of a liquid-liquid phase separation system. This technique can be applied to a multitude of biological heterogenous scenarios such as nucleolus characterization, high concentration lipid sites, dynamic protein aggregates and more.
Waveguide demultiplexer based on Helmholtz-resonator mediated extraordinary acoustic transmission
Authors: Robertson William M. , Carlyon Robert , Sprague Kyle
Published: November 2022

The design of an acoustic demultiplexer based on in-line Helmholtz resonators is demonstrated analytically via a modified transfer matrix method and computationally through finite element simulations. The modeled system consists of a single input waveguide that splits in a Y-configuration into two output waveguides. Each output arm has a single tuned Helmholtz resonator embedded in-line along the length of the guide. The Helmholtz resonators in each arm consist of a single cavity with two necks—one directed towards the input and output sides of the guide. The phenomenon of extraordinary acoustic transmission results in near perfect transmission of sound along each output arm in a small frequency interval about the Helmholtz resonant frequency. The demultiplexed frequencies are determined by the physical dimensions of the Helmholtz resonator. Using a single Helmholtz resonator in each output arm means that the system is more compact compared to other proposed schemes using either side-loaded Helmholtz resonators or stubs.
Impedance tube method for characterization of one-dimensional electro-momentum coupled materials
Authors: Casali Matthew A. , McNeese Andrew R. , Wallen Samuel P. , Haberman Michael R.
Published: November 2022

Electro-momentum coupling is a macroscopically observable material response resulting from heterogeneous piezoelectric media with microscale asymmetries that produce unique cross-coupling between the bulk momentum of the material and the generated electric field. Recently, Pernas-Salomon et al. used a one-dimensional transmission line model to demonstrate that the electro-momentum coupling effect must be considered in order to retrieve physically meaningful effective properties of heterogeneous media with subwavelength asymmetries [Wave Motion 106, 102797, (2021)]. This work presents the specialization of their transmission line model to the classical impedance tube measurement technique in which the scattering coefficients and the spatial averages of the mechanical and electrical fields of a one-dimensional material can be measured in order to obtain estimates of the frequency-dependent effective properties of an electro-momentum coupled sample. We investigate an idealized analytical approximation and then a finite element model of the realistic impedance tube configurations in order to link the analytical model to realistic experimental conditions and geometry. We then provide preliminary test results extracted from an electro-momentum coupled unit cell in a water-filled impedance tube. [Research sponsored by the Defense Advance Research Project Agency and the Army Research Office and was accomplished under Grant No. W911NF-20-1-0349.]
Microphone vibration sensitivity: What it is, why it is important, and how to measure it
Authors: King Charles B.
Published: November 2022

Microphones are designed to respond to acoustic pressure fields, but they can also be excited by external sources of mechanical vibration. In hearing aids, feedback is a difficult problem to resolve due to the high gain used to amplify sounds. The problem is worsened by the location of microphones and loudspeakers in close proximity, coupling both the acoustic and mechanical feedback paths. The first proposals of microphone vibration measurement techniques and definitional structure were published by Mead Killion in the 1970’s. Significant improvements in measurement technique have been published over the last 10 years. This talk will focus on a new measurement technique that allows for direct measurement of the “intrinsic vibration sensitivity”. The technique gives the ideal zero acoustic pressure condition at the microphone port and isolates room acoustic noise from the desired vibration signal. The noise floor of the new technique is 30 dB below previous methods, allowing for exceptionally clean measurement of primary-axis vibration sensitivity up to 10 kHz. Improvements are robust enough to enable the clean measurement of off-axis sensitivity of the microphone, which is often below 50 dBspl equivalent at 9.81 m/s2 of acceleration.
Examining the links between subphonemic sensitivity and nonnative speech perception
Authors: Kapnoula Efthymia
Published: November 2022

In general, listeners are sensitive to acoustic differences within their L1 phonemic categories (Andruski et al., 1994; McMurray et al., 2002; Toscano et al., 2010). However, some listeners appear to be more sensitive to subphonemic information than others (Kapnoula et al., 2017; Kong & Edwards, 2016). Recent electrophysiological evidence points to an early perceptual locus behind these individual differences; listeners with higher subphonemic sensitivity exhibit more linear (less warped) encoding of acoustic cues (Kapnoula & McMurray, 2021). It is unclear how these individual differences come to be and how they may affect listeners’ ability to learn a new language. Here, I will discuss the potential role of bi/multilingual exposure in shaping speech perception and I will present data that offer valuable insights into how subphonemic sensitivity may be linked to nonnative speech perception.
A computational Bayesian processor for inference regarding range, depth, and velocity of a mobile scatterer under limited aperture
Authors: Barros Abner C. , Gendron Paul J.
Published: November 2022

A computational Bayesian framework for inference regarding the range, depth and velocity of a submerged mobile localized body in an ocean waveguide is constructed. The approach incorporates the various mixed mode Doppler-frequency dispersion effects associated with the reverberant body’s vertical angle scattering. Such coupled eigen returns present angle-frequency modes of intermediate Doppler residing between that of the two coupled specular eigen path Doppler frequencies. It is exactly these modes which present a severe limitation to exploiting closely spaced arrivals in coherence and aperture limited environments. Conditional densities of arrival angle-Doppler are solved via a fast inverse quantile sampler. All other conditionals offer closed form representations in the Gaussian-inverse gamma family. The joint posterior probability density (PPD) of the arrivals are numerically solved and the implied PPD of the object's range, depth, and speed is inferred through acoustic ray interpolation. Case studies are presented with various refractive ocean waveguide environments as well as iso-velocity cases. The framework offers a means of incorporating spatio-temporal arrival structure for recursive tracking in an active sonar system. [Work is funded by the Office of Naval Research.]
Lisa Zurk's contributions to MIT Lincoln Laboratory
Authors: Watson Jennifer A.
Published: November 2022

Lisa Zurk made numerous technical contributions making a substantive impact on the ISR community at a national level. This talk will highlight some of her many technical contributions, ranging from early work in UHF and VHF propagation in rough, overland, terrain, to her pioneering work in adaptive signal processing applied to underwater acoustics. This talk will also recognize her outstanding leadership, always pushing the boundaries as a researcher and as a leader, laying the groundwork for future ISR decision support and architectures. The talk will close with a summary of her role as a mentor and colleague who always challenged those around her to bring out their best. DISTRIBUTION STATEMENT A. Approved for public release. Distribution is unlimited. [This material is based upon work supported by the Department of the Air Force under Air Force Contract No. FA8702-15-D-0001. Any opinions, findings, conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the Department of the Air Force.]
A survey of Lisa Zurk's contributions to physics-based signal processing in underwater acoustics
Authors: Abraham Douglas
Published: November 2022

The incorporation and exploitation of the physics of underwater acoustic propagation (including reflection and scattering) in signal and information processing can improve the performance of detection, classification, localization and tracking (DCLT) in sonar systems. This presentation will survey several areas of Prof. Lisa Zurk's research from this perspective of physics-based signal processing. Contributions are found in the areas of (i) assessing the impact of propagation through a non-stationary underwater environment on the performance of signal processing algorithms, (ii) adapting signal processing algorithms to be more robust to these environmental effects, and (iii) the exploitation of specific characteristics of the propagation channel in novel approaches to solving the above inferential objectives. Of these areas, identifying consistently observable propagation phenomena that can be exploited to improve DCLT performance is the most essential and yet the most difficult because it requires balancing just enough accuracy in the physical model with a simple enough representation to develop robust signal and information processing algorithms. Impressively, Prof. Zurk was quite successful in this crucial area of physics-based signal processing.
Non-stationary covariance estimation for adaptive beamforming
Authors: Newhall Bruce K.
Published: November 2022

Standard adaptive beamforming (ABF) assumes a quasi-stationary covariance. However, in low frequency shipping noise the covariance is not stationary, due to the relative motion of ships and receiver. A physical model was previously developed for the behavior of the covariance due to ship motion, and a technique was developed to provide improved estimation. Relatively wide filters were used previously in order to simultaneously estimate the covariance from all moving ships. It has recently been recognized the it is most important in ABF to handle the loudest ship, which is usually the closest and therefore the most non-stationary. Here we will show simulations of the results of using more narrow filters to estimate the covariance due to the loudest ship. The technique will be contrasted to a method of matched field processing with moving ships developed by Lisa Zurk, as well as with derivative-based updating, another non-stationary estimation technique. The potential to improve the estimate by using waveguide invariance across a band of frequencies will also be discussed.
3D-printed gradient-index phononic crystal lens for transcranial focused ultrasound
Authors: Kohtanen Eetu , Allam Ahmed , Erturk Alper
Published: November 2022

Transcranial focused ultrasound (tFUS) shows great promise as a noninvasive tool to treat neurological conditions such as essential tremor. The existing clinical phased array systems are mostly intended for ultrasound delivery to the center of the brain (as in thalamotomy for essential tremor), in addition to being complex and expensive. To seek an alternative focusing approach especially for the brain periphery, we explore a 3D-printed gradient-index (GRIN) lens as a simple and an orders of magnitude more cost-effective approach. The lens is constructed using a phononic crystal (PC) architecture with varying lattice geometry and hence refractive index distribution. Specifically, the lens uses an axisymmetric hyperbolic secant refractive index profile to focus ultrasonic waves generated by a 1 MHz single-element ultrasonic transducer. Finite element simulations are performed to design and analyze the GRIN-PC lens, and to explore the effects of various parameters such as the distance from the skull and the incidence angle. The numerical results are validated experimentally for a 3D-printed lens by scanning the 3D pressure field generated through a temporal bone. This cost-effective approach to tFUS can open new possibilities to 3D print lenses based on patient computed tomography scans for various applications from tissue ablation to neurostimulation.
Superresolution using synthetic shaped acoustic vortex waves in water
Authors: Groopman Amber M. , Guild Matthew D.
Published: November 2022

Acoustic vortex waves have previously been shown to be able to overcome the diffraction limit, through the use of subdiffraction-limited pressure nulls that propagate well into the farfield. Acoustic vortex waves, therefore, present a novel means to achieve farfield superresolution imaging. However, generating acoustic vortex waves in an experimental setting typically requires a complicated phased array consisting of multiple active elements in a fixed geometrical configuration. In this work, we describe how an acoustic vortex wave can be generated using a synthetized vortex wave array applied during post-processing to in-water 2D plane measurements obtained with a single moving acoustic source and a fixed receiver. The geometric versatility of the synthetic vortex array enables different shaped acoustic vortex patterns to be achieved using the same in-water measurements. Experimental and theoretical results of the magnitude and phase of the nearfield and farfield pressure fields will be presented for a variety of geometric configurations and vortex integer wave modes of the synthesized vortex wave array. The data show excellent agreement with expected results and demonstrates shaped acoustic vortices with superresolved features in both the nearfield and farfield. [Work supported by the Office of Naval Research.]
Thrombolytic efficacy of histotripsy combined with thrombolytic-loaded echogenic liposomes
Authors: Centner Connor , Bhargava Aarushi , Huang Shaoling , McPherson David D. , Bader Kenneth B.
Published: November 2022

Deep vein thrombosis (DVT) is a substantial burden to the American public. Thrombolytics drugs are the front-line approach to treat the most egregious forms of DVT. Histotripsy is a bubble-based focused ultrasound therapy that enhances thrombolytic activity while simultaneously breaking down erythrocytes within the thrombus mechanically. Loading thrombolytics inside echogenic liposomes may accentuate the action of histotripsy via site-specific thrombolytic release and prompt bubble nuclei. The objective of this study was to assess clot degradation under the action of histotripsy and echogenic liposomes in an in vitro venous flow model. Histotripsy pulses were applied along the length of the clot at pulse peak negative pressures of 0 (control) or 42 MPa. Echogenic liposomes were diluted into the perfusate such that the thrombolytic concentration was 0 or 2.68 μg/ml. The combination of histotripsy and echogenic liposomes displayed increased clot mass loss, thrombolytic activity, hemolysis, and intact erythrocytes in the perfusate relative to echogenic liposomes alone (ANOVA p < 0.05, n = 6–8/group). Expect for hemolysis, markers of clot degradation were increased for histotripsy and echogenic liposome arms relative to histotripsy exposure alone. Together, these data indicate histotripsy combined with thrombolytics is a promising approach for the treatment of DVT.
Histotripsy significantly decreases tumor viability in neuroblastoma xenograft model
Authors: Iwanicki Isabella J. , Wu Lydia , Flores-Guzman Fernando , Centner Connor , Bader Kenneth B. , Hernandez Sonia
Published: November 2022

Children diagnosed with high-stage neuroblastoma (NB) have a <50% 5-year survival rate, resisting intensive treatment. Histotripsy, a focused ultrasound method, can ablate subcutaneous tumors. Here, we characterize histotripsy in an abdominal NB-xenograft model.Intrarenal injection of NGP-Luciferase cells in female NCr Nude mice generated 1–2 g NB tumors after 5–6 weeks. We assessed tumor viability with bioluminescence before, after, and 24h after Histotripsy. A 1-MHz focused source under ultrasound image guidance delivered 4–6 pulses per tumor with individual targets separated by ∼1 mm. Immunostains of the apoptosis marker TUNEL, endothelial marker Isolectin-B4, and hypoxia-marker pimonidazole were imaged or scanned. Statistics were performed using Graphpad.Histotripsy decreased bioluminescence by ∼50% (p = 0.02, n = 7), suggesting a decrease in viability. Untreated tumors did not change (n = 4). TUNEL staining increased in Histotripsy-treated tumors compared to controls (56 ± 6 versus 9 ± 3 %area, n = 3 to 8, p < 0.0001). Histotripsy increased pimonidazole positivity adjacent to targeted areas, suggesting hypoxia. Finally, Histotripsy increased red blood cells compared to controls. Histotripsy dramatically reduces tumor viability by inducing apoptosis of targeted areas. Hypoxia patterns suggest histotripsy alters perfusion and/or permeability within the tumor, indicating potential for synergy with chemotherapy.
Finite-difference diffusion-equation modeling of reverberation chambers in time-domain
Authors: Zhang Jiahua , Navarro Juan , Xiang Ning , Nolan Mélanie
Published: November 2022

Conventional chamber-based methods of random incidence absorbing coefficients overlook the non-diffused sound field in the room acoustics, which decreases accuracy and may even lead to conflicting results. This work applies the diffusion equation model to room-acoustic simulations of standardized reverberation chambers. The simulations can more efficiently capture the chamber's non-diffuse sound field and energy flows than wave-based simulation models. The diffusion equation represents the governing equation of reverberant sound energy densities within the reverberation chamber which is solved using the finite-difference time-domain method. Its computational efficiency of diffusion equation-based modeling lies in a highly sparse domain meshing condition dictated by the mean-free path length rather than wavelengths and still derives a wideband simulation result. This work also dedicates the effort to reexamine the meshing condition, particularly for standardized finite sizes of sound absorbers for measurements of random incidence absorption coefficients. By comparing the outcomes of simulations with measurement data, an a posteriori absorption coefficient is inversely estimated involving Bayesian parameter estimation.