bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantifying and transferring environmental uncertainties in underwater acoustic modeling
Authors: Dosso Stan , Tollefsen Dag
Published: May 2022

Uncertainties in environmental inputs represent a major source of uncertainty in underwater acoustic model outputs and applications thereof (e.g., transmission-loss estimation, source localization). Seabed geoacoustic parameters are often estimated by the inversion of ocean acoustic data. Hence, rigorous quantification of geoacoustic inversion uncertainties and the transfer of these uncertainties to modeling applications are of key importance. Uncertainty estimation in geoacoustic inversion is naturally accommodated in a Bayesian formulation, which combines data and prior information to form the posterior probability density (PPD) of seabed parameters. Important components of this approach include quantitative model selection for seabed parameterizations consistent with the information content of the data; an appropriate model for residual data errors that specifies the likelihood function; and nonlinear estimation of the PPD, which is normally carried out using Markov-chain Monte Carlo (MCMC) methods. MCMC characterizes the PPD using a large ensemble of dependent random samples of the geoacoustic parameters, which can be computationally demanding. However, these uncertainties can be transferred efficiently to subsequent propagation-modeling applications using a much-smaller, randomly chosen (independent) subset from the ensemble. The approach is illustrated using simulations and inversion of ship noise recorded on a horizontal array of hydrophones at the New England Mud Patch.
The sonar equation versus reality: Inherent non-environmental variability in detection range
Authors: Kessel Ronald
Published: May 2022

Acoustic Range Prediction uses the sonar equation to forecast the “detection range,” which is naturally understood by many to be the expected detection range in a closing-target encounter. Its variability is then the difference between actual and forecast detection ranges. The difference is often attributed to imperfect representation of the ocean environment (propagation and background levels). But the sonar equation’s original design-orientation and its terminology have at times caused misunderstanding. It is shown that the sonar equation’s detection range marks the sweet-spot of coverage, in which target detection is expected to be easy (fast and reliable), but which generally cannot be interpreted as the expected range or outer limits of detection in closing-target encounters. The classical and expected detection ranges concepts are disentangled here, giving each its appropriate roles in design, planning, and operations. It is also shown that, quite apart from environmental variability, there remains an inherent, significant variability of detection range simply because (1) the probability of detection increases slowly for a distant closing target, and (2) the target depth is unknown (unalerted detection). A significant degree of coverage variability therefore generally remains even if the environmental knowledge is perfect.
Understanding uncertain acoustic propagation in deep ocean environments for feature engineering in corresponding machine learning tasks
Authors: Lee Brandon M. , Johnson Jay R. , Dowling David R.
Published: May 2022

Transmission loss (TL) predictions obtained using models of deep ocean environments are often uncertain due to imperfect knowledge of environmental properties such as sound speed, bathymetry, and seabed properties. These environmental uncertainties can be transferred to TL-prediction uncertainty by Monte Carlo (MC) sampling over environmental parameters and performing TL-field calculations to obtain an MC probability density function (PDF) of TL. Unfortunately, thousands of TL-field calculations are often required to quantify the TL uncertainty making this approach ill-suited to real-time applications. In an alternative, supervised learning approach, neural networks can be trained to quickly estimate the MC PDF of TL at a point of interest by analyzing the variability in the values of a baseline TL-field prediction within a region surrounding that point. The size, shape, and number of local TL region(s) used as inputs to the neural network can be reengineered by better understanding the means by which the uncertainties in environmental properties affect the TL uncertainty. This process and the resulting improvements in predictive performance are demonstrated for acoustic frequencies of 50 to 600 Hz, and source-receiver ranges up to 100 km. [Work sponsored by an NDSEG Fellowship.]
Acoustic comfort in health care facilities: Perspective of FGI-Facility Guidelines Institute
Authors: Rockstroh Kurt , Sykes David , Kachur Mandy
Published: May 2022

Acoustic comfort is a welcome concept for the design and management of healthcare facilities, potentially providing methods to address acoustic environment deficiencies revealed by experience and by the Affordable Care Act’s CAHPS® Hospital Survey, on which the noise question historically performs worst yielding public disclosure and financial penalties to hospitals. One possible vehicle for introducing quantified acoustic comfort into buildings is the healthcare design guidelines published by the Facility Guidelines Institute (FGI), which are adopted as building code in a majority of the United States, provide reference standards for the Leadership in Energy and Environmental Design (LEED) Rating System and the International Green Construction Code, and are cited in 87 countries. For acceptance into the FGI guidelines, “acoustic comfort” requires a formal definition accepted by standards organizations and clinical research, which is free from conflicts of interest based on research conducted by recognized third-party organizations on the physiological and psychological effects of noise on humans, particularly those with compromised health, like patients in hospitals and skilled nursing facilities. FGI encourages proposals from the public, particularly valuing advice from members of professional societies, and relies on the research community to provide evidence-based support for all acoustics topics.
Cetacean acoustic monitoring across the Hawaiian archipelago: Building on Whitlow Au’s legacy
Authors: Lammers Marc , Zang Eden J. , Kügler Anke , Martinez Jonathan , Merkens Karlina , Hatch Leila
Published: May 2022

The Hawaiian islands are home to more than 20 species of cetaceans and are the principal breeding ground of the north Pacific humpback whale population. The archipelago stretches more than 2500 km from Hawaii Island to Kure Atoll, creating a significant challenge for monitoring the occurrence and distribution of cetaceans across such a vast range. To meet this challenge, the National Oceanic and Atmospheric Administration and the U.S. Navy have been engaged in a three-year effort to monitor the marine soundscape of the Hawaiian archipelago known as the SanctSound Project. Bottom-moored acoustic recorders were deployed at multiple locations across the Hawaiian Islands Humpback Whale National Marine Sanctuary and the Papahānaumokuākea Marine National Monument to examine the occurrence of humpback whales and odontocetes based on the relative prevalence of their acoustic signaling. Anthropogenic sound sources were also studied to understand how these co-occur with cetaceans. Substantial spatial and temporal variability was observed in the prevalence of whale song and dolphin acoustic activity across locations with high cetacean presence sometimes overlapped with elevated anthropogenic activity. This work helps expand our understanding of how cetaceans use the archipelago and builds on the legacy of Whitlow Au, who pioneered cetacean acoustic monitoring in Hawaii.
Insights into acoustic behavior of false killer whales
Authors: Gruden Pina , Barkley Yvonne , McCullough Jennifer L.
Published: May 2022

The Hawaiian Archipelago is home to three distinct populations of false killer whales (Pseudorca crassidens), including one currently listed as endangered. These delphinids are known to interact with fishing gear, leading to whale mortality or injury. Hence, it is critical to assess the abundance of these populations typically achieved through visual-based sighting surveys. However, these surveys are complicated by a number of biases and uncertainties specific to this species. Passive acoustics could aid in monitoring of their population status, but the knowledge is limited about the patterns in their acoustic repertoire and behavior, which hinders our ability to derive reliable acoustics-based abundance estimates. Here, we discuss insights into the acoustic behaviour of false killer whales in the wild, gained by simultaneous tracking of both narrowband whistles and broadband echolocation clicks from towed hydrophone arrays. The results indicate a diverse acoustic behaviour between different subgroups within the same encounter, where 23.8% of subgroups (N total = 408) only echolocate, 18.9% only whistle, and 57.3% emit both types of vocalizations. Such increased understanding of false killer whale vocal behavior can contribute information from passive acoustic data for management and conservation purposes.
Autumn acoustic behavior of right whales in Southern New England waters
Authors: Parks Susan , Zeh Julia , Shorter K. Alex , Foley Heather , Conger Lisa , Cholewiak Danielle
Published: May 2022

North Atlantic right whales (Eubalaena glacialis) are an endangered species of baleen whale found in high human use areas off the East Coast of the United States. Conservation efforts for this species include the use of passive acoustic monitoring to detect sounds produced by right whales to determine when they are present in areas of interest. Right whale acoustic behavior is known to vary by age, sex, and behavioral state, with differing call types and call rates found across different habitats and seasons. There are currently plans for development of offshore wind energy installations off the East Coast of the United States, including lease areas south of Massachusetts in areas known to be frequented by right whales. These development plans necessitate a better understanding of right whale acoustic behavior in this region to best inform passive acoustic monitoring efforts for right whales. In this study, we analyzed ∼38 h of data from eight suction cup archival acoustic biologging tags attached to North Atlantic right whales in October 2021 in Southern New England waters south of Nantucket. The call types and call rates by behavioral state will be discussed with the primary observed behaviors including foraging and social surface behaviors.
Investigating response to treatment of pulmonary fibrosis in rats using ultrasound multiple scattering
Authors: Roshankhah Roshan , Blackwell John , Yuan Hong , Montgomery Stephanie A. , Egan Thomas M. , Muller Marie
Published: May 2022

Lung alveoli constitute a complex distribution of strong ultrasound scatterers, leading to multiple scattering (USMS). Conventional ultrasound cannot be utilized to produce images that would accurately render lung structure. Pulmonary fibrosis affects lung microstructure by thickening alveolar walls, which changes wave diffusion and scattering patterns by modifying the distribution and size of scatterers. We present a method for the quantitative approach of structural changes in lung parenchyma based on diffusion of ultrasound waves, relying on measurement of the scattering mean free path (SMFP). We quantify severity of lung damage due to bleomycin-induced fibrosis in rats, and to monitor response to Nintedanib treatment by comparing the SMFP in 6 control (normal) lungs, 6 fibrotic lungs, and 6 fibrotic lungs from rats treated with Nintedanib. We observed significant differences in SMFP among control lungs (483 ± 50 μm), fibrotic lungs (1433 ± 612 μm), and lungs from Nintedanib-treated rats (835 ± 149 μm) (mean ± sd). Strong correlations were observed between SMFP and fibrosis severity score on inflated ex vivo CT lung images (p = 0.076, r = 0.43), as well as between SMFP and modified Ashcroft score of inflation-fixed lungs stained with H&E and Sirius red (p = 0.008, r = 0.61). This suggests SMFP may be useful to monitor response to treatment of pulmonary fibrosis.
Outdoor acoustic measurements of a rocket engine hot fire test
Authors: Kerrian Peter , McShane John , Shah Parthiv , Yang Michael , Larson Dan , Murray Bill
Published: May 2022

The primary focus of this paper is to present the results from outdoor acoustic measurements from a rocket engine hot fire test. The two objectives of the test were to quantify the overall sound pressure level at large distances from engine to quantify the impact of the events on the surrounding community, and to better understand the source distribution in the engine plume. Microphone arrays were positioned around the property to be able to capture the sound propagation, estimate source levels, and conduct phased array-based plume source localization.
Comparison of rocket launch data to empirical models for overall level and peak directivity angle
Authors: Bassett Michael S. , Olausson Samuel A. , Houston Griffin , Mathews Logan T. , Anderson Mark C. , Durrant J T. , Hart Grant W. , Gee Kent L.
Published: May 2022

With increasing frequency in global rocket launches, it is important to assess the effects of liftoff noise. Understanding of the fundamental physics of the sound radiation from rocket exhaust plumes remains limited. Some empirical predictive models, derived from plume parameters, cover aspects of the sound radiation, such as convective Mach number, peak directivity angle, and overall sound pressure level in the direction of maximum emission. These are evaluated using high-fidelity noise data from a number of different launches from Vandenberg Space Force Base. Initial results of the model comparisons will be presented.
Investigation of measured sonic boom variability and ambient noise coherence across a 400-ft linear array
Authors: Anderson Mark C. , Gee Kent L. , Durrant J T. , Mathews Logan T. , Loubeau Alexandra , Doebler William
Published: May 2022

In preparation for the NASA X-59 flight test campaign, it is relevant to understand the variability of measured sonic boom metrics over short distances. One of the measurement stations at the 2019 NASA Carpet Determination in Entirety Measurements (CarpetDIEM) campaign consisted of a 400-ft linear array of seven microphones beneath and perpendicular to the flight track. The purpose of this array was to assess variability in CarpetDIEM boom characteristics over the array aperture. Analysis shows that all candidate metrics can vary by more than 6 dB across the array and that this variability appears to be normally distributed about a mean value for the array. Confidence intervals for several boom metrics are discussed. The ambient noise coherence across the array is also discussed in relation to the sonic boom metrics. [Work supported by NASA Langley Research Center through the National Institute of Aerospace.]
Comparing the monaural effects of reverberation on speech intelligibility in noise for hearing-impaired and normal-hearing listeners
Authors: Cueille Raphael , Lavandier Mathieu , Grimault Nicolas
Published: May 2022

Reverberation has several detrimental effects on speech intelligibility in noise. They have been extensively studied with normal-hearing listeners. These effects are often simultaneous, and it is hard to disentangle the corresponding difficulties experienced by hearing-impaired listeners in noisy reverberant rooms. In this study, two monaural effects of reverberation were investigated for normal-hearing and hearing-impaired listeners with linear amplification (NAL-RP) to compensate for audibility. One is the temporal smearing of the target speech, which makes it less intelligible. The other is the temporal smearing of the noise masker, which decreases the dip listening benefit associated with envelope modulations in the noise. These two effects were studied separately and in combination, by applying reverberation either on the target speech, on the noise masker or on both. The results were analyzed using Bayesian ANOVAs and t-tests. Overall, the detrimental influence of reverberation was found similar for the hearing-impaired and normal-hearing listeners, indicating that a linear amplification of the signals seemed sufficient to compensate for the potential differences experienced by normal-hearing and hearing-impaired listeners.
Highly efficient wavefront control through bianisotropic (Willis coupling) metasurfaces
Authors: Li Junfei , Peng Xiuyuan , Song Ailing , Cummer Steven
Published: May 2022

Recent advances in metasurfaces have shown that efficient wavefront transformation can be obtained by carefully controlling the bianisotropic response (Willis coupling) in the metasurfaces. However, applying such a scheme directly for complicated wavefront transformations will lead to nonreciprocal or nonlocal response, which is difficult to realize physically. Here we identify the local power conservation requirements and introduce several strategies to meet such requirements. Our strategies include designing surface waves into the scattered field, designing power-flow conformal metasurfaces, and combining coordinate transformation with bianisotropic metasurfaces. Based on such schemes, we develop a series of bianisotropic metasurfaces design approachs for near-perfect arbitrary wavefront control. These passive and reciprocal design approaches enable experimental demonstration of highly efficient, arbitrary wavefront transformation.
Willis coupling in strictly one-dimensional bulk media
Authors: Muhlestein Michael B.
Published: May 2022

Willis coupling, which couples the constitutive equations of an acoustical material, has been applied to acoustic metasurfaces with promising results. However, less is understood about Willis coupling in bulk media. In this talk, a variational homogenization method is used analyze the source and interpretation of Willis coupling in one-dimensional bulk media without any hidden degrees of freedom, or strictly one-dimensional media. As expected from previous work, Willis coupling is shown to arise from geometric asymmetries, but is further shown to depend greatly on the measurement position. In addition, a discussion of the predicted material properties, including Willis coupling, of macroscopically inhomogeneous media is presented.
An analytical framework and model for de-racializing vocal perception
Authors: Eidsheim Nina S.
Published: May 2022

Based on 20 years of research into vocal techniques, vocal styles, pedagogy, and history with reference to opera, popular music, and music synthesis software, I have developed a framework that seeks to explain racialized perceptions of the singing voice. On one hand, my model accounts for voice as an ever-developing instrument affected by age, hormones, environment, culture, and vocal training (whether through formal voice lessons or everyday encounters’ largely tacit feedback). On the other hand, it also accounts for perception as equally dynamic and culturally dependent. It recognizes that the voice and its perception together constitute a “thick event,” and that the complexity of the vocal signal and the ways in which listeners interact with voices are so numerous and so complex that a speaker’s race cannot be defined by the signal. In other words: Voice is not singular; it is collective. Voice is not innate; it is cultural. Voice’s source is not the singer; it is the listener. By applying this analytical model to musical case studies, this paper argues that voices are racialized when they are believed to sound a person’s essence or true identity.
Deep reinforcement learning for cognitive active-sonar employment
Authors: McMillan Justin R. , Botts Jonathan , Summers Jason E.
Published: May 2022

We introduce a framework to leverage deep reinforcement learning (RL) for active sonar employment, wherein we train an RL agent to select waveform parameters, which maximize the probability of single-target detection. We first simulate raw sonar returns of targets and clutter in reverberation and noise using a physics-based sonar-simulation model, the Sonar Simulation Toolkit (SST), then process the resulting signatures into network inputs via an in-house signal and information processing model of an archetypal antisubmarine warfare (ASW) processing chain. We demonstrate that the trained RL agent is able to appropriately select between continuous wave (CW) and hyperbolic frequency modulated (HFM) waveforms depending on target trajectory, as well as select an optimal bandwidth and pulse length trade-off (when constrained by a constant time-bandwidth product), when presented with sonar returns from a reverb-limited or noise-limited environment.
Bioacoustics and beyond: Investigating animal sensory systems and cognitive processes
Authors: DeLong Caroline M. , Fobe Irene , Morrison Evan , Wegman Jessica
Published: May 2022

Whit Au served on my dissertation committee at the University of Hawaii and mentored me while I was in the Marine Mammal Research Program at the Hawaii Institute of Marine Biology (1997–2003). He guided me through the process of recording echoes from objects ensonified by dolphins and oversaw my first human listening study. When I became a professor, I continued to study dolphin bioacoustics. I also broadened the scope of my research program to accommodate the interests of my students, just like Whit did. In this talk, I will summarize several animal perception and cognition projects I have pursued with my graduate students. First, we explored how humans discriminate acoustically among bottlenose dolphin signature whistles with and without masking by boat noise. In another study, we investigated auditory rhythm perception in African penguins. Next, we researched long-term memory in river otters using multimodal stimuli. One of our current projects focuses on visual object perception and learning in olive baboons. I will always be grateful for Whit’s support when I was in graduate school and I will continue to follow his model for graduate student mentoring in the future.
Optimal control of the nonspherical oscillations of encapsulated microbubbles
Authors: Arifi Fathia F. , Calvisi Michael L.
Published: May 2022

Encapsulated microbubbles (EMBs) were originally developed as contrast agents for ultrasound imaging but are more recently emerging as vehicles for intravenous drug and gene delivery. Ultrasound can excite nonspherical oscillations, or shape modes, that can enhance the acoustic signature of an EMB and also incite rupture, which promotes drug and gene delivery at targeted sites. Therefore, the ability to control shape modes can improve the efficacy of both the diagnosis and treatment mediated by EMBs. This work uses optimal control theory to determine the ultrasound input that maximizes a desired nonspherical EMB response (e.g., to enhance scattering or rupture), while minimizing the total acoustic input in order to enhance patient safety and reduce unwanted side effects. The optimal control problem is applied to a model of an EMB that accounts for small amplitude shape deformations. This model is solved subject to a cost function that maximizes the incidence of rupture or acoustic echo while minimizing the acoustic energy input. The optimal control problem is solved numerically through pseudospectral collocation methods using commercial optimization software. Single frequency and broadband acoustic forcing schemes are explored and compared. The results show that broadband forcing significantly reduces the acoustic effort required to incite EMB rupture relative to single frequency schemes. Furthermore, the acoustic effort required depends strongly on the shape mode that is forced to become unstable.
Ultrasound contrast agents: From buckling dynamics to swimming
Authors: Chabouh Georges , Quilliet Catherine , Dollet Benjamin , Marmottant Philippe , Coupier Gwennou
Published: May 2022

Cleverly engineered microswimmers have been of increasing scientific interest, as they show great promise in various biomedical applications. In this study, we propose a novel mechanism of propulsion in fluids at the microscale, using a buckling mechanism activated by pressure waves. We considered an in vivo-friendly hollow elastic shell of micrometric size composed of a lipidic membrane enclosing a gas bubble. Such microshells are approved for clinical use as diagnostic ultrasound contrast agents (UCAs). We experimentally investigate the buckling dynamics of microshells upon an increase of external pressure. The effect of the driving frequency is studied as well as that of the size and mechanical properties of the microshells. We evidence a non-zero displacement upon a complete cycle of deflation and re-inflation of the microshells, which includes buckling events. The proposed propulsion mechanism whose direction is controlled in the shell reference frame can be an answer to the problem of directivity accounted in the acoustic radiation force technique used in ultrasound molecular imaging and drug delivery.
Analysis of cavitation induced stresses on blood vessel wall during photo-mediated ultrasound therapy using finite-element based numerical models
Authors: Singh Rohit , Yang Xinmai
Published: May 2022

Photo-mediated ultrasound therapy (PUT) is a novel technique, which utilizes spatio-temporally synchronized pulsed laser and ultrasound to produce enhanced cavitation inside blood vessels. Vascular bio-effects during PUT, such as reduced perfusion rate and rupture of blood vessel, are thought to be due to shear and circumferential stresses induced on vessel wall. We have developed a 2D axisymmetric and a 3D finite-element method (FEM)-based models in COMSOL Multiphysics to calculate the stresses induced on vessel wall during PUT. The 2D axisymmetric model simulation showed that drastic increase in bubble size with PUT application resulted in higher shear and circumferential stresses as compared with ultrasound application only in the beginning phase of PUT. The 3D model simulation showed increase in stresses when a bubble moves towards the vessel wall, and found relatively higher increase in shear stress as compared to circumferential stress. The 2D results were imperative in understanding of PUT inception resulting in stronger stresses on vessel walls, which were otherwise almost zero for ultrasound-only. The 3D results demonstrated that the stresses on vessel walls further increased during the subsequent phase of PUT, enough to induce vascular bio-effects.
A standardised and evidenced-based lung ultrasound acquisition protocol and scoring system for the monitoring and stratification of COVID-19 and post-COVID-19 patients
Authors: Demi Libertario , Mento Federico , Di Sabatino Antonio , Fiengo Anita , sabatini umberto , Macioce Veronica N. , Robol Marco , Tursi Francesco , Sofia Carmelo , di Cienzo Chiara , Smargiassi Andrea , Inchingolo Riccardo , Perrone Tiziano
Published: May 2022

Lung ultrasound (LUS) is currently utilized worldwide to assess COVID-19 patients. However, imaging protocols are often defined arbitrarily, and studies on post-COVID-19 are lacking. In this work, we report on the capabilities of standardized LUS to monitor and stratify COVID-19 and post-COVID-19 patients. A validated and standardized imaging protocol based on 14 scanning-areas and a 4-level scoring system were utilized to collect and analyze data from 220 patients, 100 COVID-19 positive, and 120 post-COVID-19. Next, the capability of five imaging protocols (based on 4, 8, 10, 12, and 14 scanning-areas) to intercept the most significant LUS findings was compared. Moreover, a longitudinal-study was conducted aiming at investigating the possibility to simplify the protocol during follow-up. Results on the agreement between AI-models and LUS experts with respect to LUS data evaluation are also reported. In conclusion, a 12-areas protocol emerges as the optimal trade-off between a time-efficient and an accurate LUS examination. However, it appears not to be possible to reduce further the number of scanning-areas during follow-up. Finally, COVID-19 and post-COVID-19 data seem to show differences capable to confuse AI models that were not trained on post-COVID-19 data, supporting the hypothesis of the existence of LUS patterns specific to post-COVID-19.
On the impact of pixel resolution on automated scoring of lung ultrasound images from coronavirus disease 2019 patients
Authors: Khan Umair , Mento Federico , Giacomaz Lucrezia N. , Trevisan Riccardo , Smargiassi Andrea , Inchingolo Riccardo , Perrone Tiziano , Demi Libertario
Published: May 2022

With the outbreak of the COVID-19 pandemic, remote diagnosis, patient monitoring, collection, and transmission of health data from electronic devices are rapidly taking its share in the health sector. These devices are, however, limited on resources like energy, memory, and processing power. Consequently, it is highly relevant to investigate how to minimize the size of data, keeping intact the information content. The objective of this study is to, thus, observe the impact of pixel resolution on the automated scoring by DL algorithms for LUS videos. First, 448 videos from 20 patients were normalized to a common pixel resolution, i.e., the largest found over the dataset (841 pixels/cm2). Next, the pixel resolution was further reduced by factor 2 by resampling the normalized data to 210 pixels/cm2. Original, normalized and re-sampled videos were evaluated using the DL algorithm [Roy et al., IEEE Trans. Med. Imaging 39, 2676–2687 (2020)]. At frame level, for normalized and resampled videos, the level of agreement of DL results with the original videos was 93.2% and 86.6%, respectively. Similar performance was found at video level with the agreement to 95.75% and 85.93%, respectively. The study showed that with a significant reduction in the pixel resolution of LUS data, low variation in the DL performance is observed.
A Capstone Acoustical Engineering Design course with industry-sponsored projects
Authors: Jasinski Christopher M. , Celmer Robert
Published: May 2022

One of the transitions that engineering students must make as they enter the work force is the progression from theoretical concepts to applied/real world applications. At the University of Hartford, engineering design courses serve as culminating experiences devised to bridge this passage. One such course, Acoustics Capstone Design, challenges the student to apply the past three years' conceptual base of two acoustics and two vibration courses to a problem-solving opportunity replete with actual scenarios encountered in industry. Each year local firms approach our Engineering Applications Center for assistance with a variety of sound or vibration problems. After an initial training period, students make use of the laboratory's FFT/real time analyzers, anechoic/reverberation chambers, sound intensity and modal analysis software, acoustic modeling software, and vibration shaker/transducers. Using a consultant-client model, students work collaboratively in teams of two defining the problem, developing a method of approach, making appropriate measurements, devising alternate solutions, and ultimately delivering a written and oral presentation at the end of the semester. The arrangement regularly results in employment offers for the graduating seniors. The paper discusses specific projects and some experiences students have had with their first industrial assignment, as well as creative means of equipment acquisition.
Underwater acoustic spiral wave navigation system
Authors: Di Bona Isabella , Gravelle Christopher , Faddi Zakaria , Brown David A. , Bachand Corey
Published: May 2022

A spiral wave navigation beacon is described that creates an outgoing signal with a wavefront that is a diverging spiral cylindrical wave followed by a reference signal of circular wavefront as previously described by Dzikowicz and Hefner in JASA. In this demonstration, the signals are created by driving a cylindrical transducer’s orthogonal sine and cosine modes of vibration in phase quadrature as previously described by Brown and Bachand in JASA. The two dipolar radiation patterns combine to create a helically diverging spiral wavefront that may be used for navigation and communication. The electronic system design and transducer characterization will be presented and are the subject a senior-capstone design project in the College of Engineering at UMass Dartmouth for four of the authors (I.D.B., C.G., K.C., Z.F.). [The project provided a multidisciplinary opportunity in acoustical engineering, instrumentation, calibration, and signal processing and was sponsored by industry (BTech).]
Working with industry to create new educational pathways for students to diversify the acoustics workforce
Authors: Riegel Kimberly A.
Published: May 2022

Many undergraduates are not aware of the opportunities that a career in acoustics provides. To meet the students where they are and provide more representation in the field, we need to create new pathways. One big hurdle for first time, low-income students is that they are working while attending classes. The STEM pipeline is changing, and students are taking different pathways as they navigate their academic careers in addition to their other responsibilities. More than 60% of students attend community college at some point in their careers, and more than 70% of students attend a public university with many of those colleges being minority serving institutions. I am proposing to create an acoustical technician track that would allow students to learn practical skills that would allow them to enter the workforce earlier. These degrees would need to be developed alongside industry to ensure that the students would be particularly prepared for the local needs of the industry. This will also financially allow students to continue their education if they choose.
The need for appliance sound ratings
Authors: Taylor Corey , Herreman Kevin
Published: May 2022

Home life has changed over the past 50 years with appliances, providing automated cycles to aid in storage, cleaning, and cooking. Appliances have proven to do tasks conveniently with more efficiency than people. Home designs have changed to adapt to the change in lifestyles. Locating the appliances close areas where they are needed is a highlight of home designs. Clothes washers, long relegated to the basement in older homes have found their way into the main living areas. The price of that convenience is the increase in background sound levels in typically quiet areas of the home. Consider that the sound emitted by a clothes washer in the spin cycle is of similar levels as a car passing a person standing on the side of the road or traffic noise. This level of sound can be disruptive in the home, especially if the appliance is in the main living space or near the bedrooms. In the early 2000s, a major appliance retailer implemented a sound level rating for dishwashers that provided data for customers to compare products. This paper will discuss the positive effects of that standard on dishwasher sound and discuss the need for additional appliance sound level ratings.
Sonic boom focus modeling of benchmark cases using the PCBoom suite
Authors: Downs Robert , Kaye Sophie
Published: May 2022

Focusing of sonic booms is a phenomenon that can arise from particular atmospheric conditions or aircraft trajectories including acceleration, turns, or other variations from steady level flight. Because such maneuvers are unavoidable, development of regulations for civil supersonic flight will depend on the capability to understand and predict the scenarios in which focus booms can lead to ground overpressures several times higher than typical carpet booms. Models for predicting sonic boom focal zones and focus boom signatures have been developed by several organizations, and a recent AIAA Sonic Boom Prediction Workshop provided an opportunity to compare results among such models. Rallabhandi et al. developed benchmark cases to further extend verification of focus boom models. The PCBoom suite of tools, including the lossy nonlinear Tricomi equation (LNTE) module, was used to predict caustic geometry and pressure signatures near the caustic arising from a constant acceleration level trajectory and also from an accelerating climb trajectory. A recently developed methodto streamline the focus boom modeling process within PCBoom was exercised as part of this benchmark case evaluation. [Work supported by the National Aeronautics and Space Administration under project VXAHA321.]
Single focused-beam acoustical tweezers
Authors: Gong Zhixiong , Baudoin Michael
Published: May 2022

Single beam acoustical tweezers have seen rapid development for their potential applications in vitro and in vivo in different fields such as acoustofluidics, microrobotics, precision medicine, and so on. The first single beam acoustical tweezers used a focused beam in analogy with optical tweezers [Lee et al., Appl. Phys. Lett., 95, 073701 (2009)]. However, they only succeeded to trap light particles with negative acoustic contrast factor in two dimensions. In this talk, we revisit theoretically the capabilities of acoustical tweezers based on focused beams and demonstrate that they can trap (i) some specific light elastic particles and droplets in three dimensions in and beyond the Rayleigh regime, (ii) dense particles (with positive acoustic contrast factor) in two dimensions near the resonance frequencies, and (iii) lipid cells in three dimensions. Some preliminary experimental results will be presented.
Testing the generation of harmonic templates from coincidence patterns in response to noise: Physiological and modeling considerations
Authors: LI Yi-Hsuan , Joris Philip X.
Published: May 2022

Harmonic templates are a critical component of spectral pitch theories. Shamma and Klein (2000) hypothesize that such templates can arise from neural coincidence patterns in response to stochastic stimuli without pitch.The key feature of their computational model is a higher number of coincidences between neurons with harmonically related characteristic frequencies (CFs). We tested the hypothesis with physiological data and a computational model. We recorded neural responses in chinchilla to various periodic and non-periodic stimuli, both from the auditory nerve and the trapezoid body. We then examined counts of spike coincidences across fibers. The key prediction of a higher number of coincidences between pairs of fibers with harmonically related CFs than for other pairs was observed for responses to narrowband signals (tones at CF), but not to broadband noise. We then tested a model similar to that of Shamma and Klein. Only with cochlear filters sharper than plausible even in humans, followed by additional spectral sharpening through lateral inhibition and extreme temporal sharpening, do we obtain harmonic templates similar to their model. Although our results do not speak to the existence of harmonic templates per se, we conclude that the specific mechanism of this hypothesis has little physiological plausibility.
Towards auditory stream segregation in Tursiops truncatus
Authors: Schalles Matt , Mulsow Jason , Houser Dorian , Finneran James J. , Tyack Peter , Shinn-Cunningham Barbara
Published: May 2022

In humans, understanding a voice amidst competing sounds depends on parsing the sound mixture into “streams” representing each source's content. Streaming can be influenced by top-down attentional focus, while acoustic features can affect streaming percepts through bottom-up, automatic processing of pitch, timbre, and location. Dolphins regularly navigate a cacophony of echoes generated during echolocation, conspecific echolocation clicks, and other, passively received sounds (eg. communication signals, environmental noise), and thus, may rely on streaming. Using auditory evoked potentials (AEPs), we asked whether dolphins exhibit evidence of bottom-up, frequency-based stream segregation. Initial results using a classic A-B-A sequence of repeated tone triplets (either low-high-low or high-low-high tones) suggest that the triplets break apart perceptually into low and high streams; specifically, the AEP magnitude evoked by the middle tone increases with increasing frequency separation. Differences in dolphin hearing sensitivity across the frequencies tested seem to account for some of the frequency manipulation effect. Additionally, earlier studies suggest that the dolphin auditory temporal integration window decreases as frequency increases, which may interact with streaming processes. This lays a foundation for future tests of top-down effects on dolphin auditory stream processing such as attention and expectation.
Perception of temporal cues in word segments under bimodal divided attention in simulated cochlear implant listening
Authors: Song Viv , Brown Hannah , Low Michelle , Xie Zilong
Published: May 2022

Auditory temporal processing is important for cochlear-implant (CI) users to understand speech. Speech processing often unfolds along with sensory inputs from other modalities. This study examined whether dividing attention across modalities affects temporal processing of word segments in simulated CI listening. Adults with normal hearing performed categorization tasks on unprocessed and 8-channel vocoded versions of a Dish-Ditch contrast with varying silent intervals preceding the word-final fricative. The categorization performance was measured concurrently with a visual working memory task on meaningless images. This divided attention (AV-div) condition was compared with an audiovisual selective attention (AV-sel) condition in which participants focused on the categorization task and ignored the visual stimuli, and with an auditory-only (AO) condition in which participants performed the categorization task without the visual stimuli. Preliminary results (N = 5) revealed that participants tended to report more “Dish” responses for words with longer silence intervals under the two AV conditions than the AO condition, especially for the AV-div condition. The AV-related effects on the categorization performance appear to be reduced for vocoded than unprocessed words. These results suggest that concurrent visual information affects auditory temporal processing, which might lead to speech understanding difficulties of CI users in multisensory contexts.
Measuring sensitivity to envelope interaural time differences by adapting modulation depth
Authors: Best Virginia , Conroy Christopher
Published: May 2022

Listeners are sensitive to interaural time differences carried in the envelope of high-frequency sounds (ITDENV), but the salience of this cue depends on several envelope properties. Making use of the fact that sensitivity to ITDENV varies systematically with the depth of modulation of sinusoidally amplitude-modulated tones, we devised a task in which modulation depth is varied adaptively to measure ITDENV sensitivity. In our task, the stimulus is a 4 kHz tone modulated at rates of 32, 64, or 128 Hz, with a fixed ITD of ±500 μs. Modulation depth is adaptively varied (in dB) and listeners make left-right judgements. The data are used to obtain a psychometric function and threshold value. For listeners with normal hearing, we find that thresholds vary with modulation rate and with sensation level as expected. This task provides us with a convenient means for investigating ITDENV sensitivity in listeners with sensorineural hearing loss. Given that this population shows enhanced sensitivity to amplitude modulation under certain conditions, generally attributed to a loss of cochlear compression, we will test the hypothesis that this translates into superior ITDENV sensitivity under similar conditions.
Feasibility of a hearing-aid speech quality index designed for noisy measurement conditions
Authors: Kates James M. , Lundberg Emily , Muralimanohar Ramesh Kumar , Arehart Kathryn
Published: May 2022

A goal in fitting hearing aids is to find settings that improve listener judgments of the amplified speech quality. Objective metrics that predict speech quality could assist in this fitting procedure and, thus, become useful tools in the clinic. The Hearing-Aid Speech Quality Index version 2 (HASQI v2) is effective in predicting speech quality ratings for speech processed through a hearing aid. However, HASQI v2 requires a signal-to-noise ratio (SNR) of approximately 40 dB to provide reliable measurements of low levels of nonlinear distortion, and this favorable an SNR is not always found in a clinical examination room or medical office where hearing-aid measurements are performed. Two modifications to HASQI v2 are considered in this presentation to improve the measurement accuracy in noisy situations. The first is applying dynamic-range compression to the test signal to enhance low-intensity speech sounds that could be masked by background noise, and the second is using a multilayer neural network to match noisy measurements to the corresponding measurements made in a quiet laboratory. The benefits of these modifications to HASQI are evaluated using a hearing-aid simulation, and verification is provided using commercial hearing-aid measurements made in an audiology clinic.
Optimizing hearing aids for music perception in noise using subjective and objective measures
Authors: D Shubhaganga , K V Nisha
Published: May 2022

The perception of music is significantly compromised in the individuals using hearing aids (HA), which becomes further degraded in the presence of noise. Although HAs are heavily optimized for speech intelligibility in noise, they often are not well optimized for music perception, especially in the presence of noise. This study investigated the effect of signal-to-noise ratios (SNR) on music processed through HAs in two programs (1- Speech & 2- Music) using subjective and objective measures. The HA (fitted to NAL-NL2) processed music stimuli in the two programs at 5 SNRs (0, + 5, + 10, + 15 & + 20) were rated perceptually by 20 normal-hearing participants on a visual analogue scale of “Adjective descriptors of Music” adapted from “Iowa Musical Background Questionnaire,” while the quality of music was objectively analyzed using a music quality index (HAAQI) using MATLAB code. Results showed that the music perception was better for higher SNRs ( + 15 & + 20) than lower SNRs (0, + 5 &+10) in both subjective and objective measures for both the programs. The effect of SNRs was more pronounced in the music program. These results emphasize the need for subjective and objective validation of HA programs for music listening in clinical setups.
The effects of aging and hearing loss on the across-frequency processing of interaural time differences
Authors: Bilokon Anhelina , Goupell Matthew J.
Published: May 2022

Aging and hearing loss cause speech understanding deficits, particularly in the presence of competing sounds, as well as temporal processing deficits, including binaural encoding of interaural time differences (ITDs). However, there is little understanding of the independent effects of aging and hearing loss on across-frequency ITD processing, which demonstrates a clear dependence on frequency weighting or “dominant” region around 600–700Hz. We hypothesize that aging and hearing loss will reduce extent of laterality of ITDs and will shift the frequency weighting lower. Young normal-hearing, older normal-hearing, and older hearing-impaired listeners will be tested on an intracranial lateralization task. The stimuli will consist of narrowband noises. They will have upper frequency boundaries = 500, 600, 700, or 800 Hz, bandwidths = 50, 100, 200, or 400 Hz, and ITDs = 0, ±0.5, ±1, ±1.5, and ±2 ms. These findings will help us better understand the role of the dominant region in across-frequency ITD processing, and how age- and hearing-loss-related changes in ITD processing may contribute to spatial-hearing deficits.