bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling the extended reaction of porous absorbers in time-domain wave-based room acoustic simulations
Authors: Pind Finnur , Jeong Cheol-Ho , Engsig-Karup Allan P. , Hesthaven Jan S. , Strømann-Andersen Jakob
Published: June 2021

The absorption properties of room surfaces have a major influence on the acoustics of rooms. In wave-based room acoustic simulations it is common practice to model room surfaces using a local-reaction approximation, instead of modeling the full extended-reaction behavior. However, previous research has indicated that the local-reaction assumption is not appropriate for surfaces that have elastic properties or fluid layers, such as soft porous materials, porous materials backed by an air cavity and airtight membranes. In this talk we present a method for incorporating the extended-reaction behavior of porous absorbers into a time-domain discontinuous Galerkin (dG) based room acoustic simulation scheme. The dG method is attractive for room acoustic simulations due to its flexibility and cost-efficiency. The porous material is modeled using an equivalent fluid model (EFM). The EFM formulation is validated analytically and experimentally, and it is shown that using the EFM leads to significant and perceptually noticeable improvements in simulation accuracy, when modeling single reflections and full room simulations with various types of porous absorbers.
Binaural reproduction of time-domain spectral element method simulations using spherical harmonic spatial encoding
Authors: Galanopoulos Anastasios , Pind Finnur , Sampedro Llopis Hermes , Jeong Cheol-Ho
Published: June 2021

In room acoustic simulations and virtual acoustics, incorporating listener's directivity is crucial for achieving listener's immersion into the simulated sound field and enabling sound localization. Two techniques are presented for extracting spatially encoded signals around a receiver location in a wave-based spectral element method (SEM) numerical scheme. Both are based on the relation between spherical harmonic encoding and the sound field's local pressure gradients. In the first technique, the encoding equations are solved by employing local finite differences incorporated into the SEM scheme. In the second, an SEM numerical discretization of the encoding equations is derived through the weak formulation of the encoding equations and solved inherently in the SEM scheme. Binaural responses areproduced by convolving the computed wave amplitude density with a head-related transfer function. Numerical results from the two techniques are presented, and an excellent agreement is found with finite-difference time-domain simulations. The encoded signal's accuracy in the two SEM techniques is analyzed in terms of the resolution of the numerical discretization. The receiver directivity models run locally, in the time domain, and support interactive auralization with moving and rotating receivers.
Developing efficient finite element techniques for atmospheric sound propagation
Authors: Kirby Ray
Published: June 2021

Applying the finite element method to problems in atmospheric sound propagation is challenging because the use of a standard approach, such as meshing the entire domain, quickly delivers a prohibitive problem size. The finite element method does, however, offer many advantages such as the ability to accommodate continuous variations in fluid properties, as well as scattering from obstacles of complex geometry. This means the method is ideally placed to provide benchmark solutions for more popular approaches. Accordingly, ideas for developing more efficient versions of the finite element method suitable for atmospheric sound propagation are explored here for two dimensional problems. These are based on the use of one dimensional normal mode expansions, and then mapping these on to two dimensional solutions for non-uniform obstacles. The normal mode solution for a range independent inhomogenous moving fluid is presented, and numerical mode matching techniques are introduced to demonstrate the inclusion of a point source. The extension of these mode matching methods to accommodate scattering from obstacles is then discussed, and the conditions necessary to deliver efficient finite element solutions are reviewed.
Virtual strings filter design revisited
Authors: Smith Julius O.
Published: June 2021

Digital filters have been used for decades to simulate losses and dispersion in real-time vibrating-string models for musical sound synthesis. String-loop filters in digital-waveguide models have generally been very low-order due to CPU limitations on typical available devices. In recent years, CPU speeds have increased so dramatically that very realistic string models can easily run in real time. This presentation revisits filter design for real-time musical string modeling.
Theoretical analysis on thermal effect of weakly nonlinear propagation of focused ultrasound toward medical applications
Authors: Kagami Shunsuke , Kanagawa Tetsuya
Published: June 2021

Toward medical applications such as a tumor ablation therapy by High-Intensity Focused Ultrasound (HIFU), weakly nonlinear propagation of quasi-planar focused ultrasound in a liquid containing many spherical microbubbles is theoretically investigated, especially focusing on thermal effects of microbubble oscillations. We shall derive a Khokhlov–Zabolotskaya–Kuznetsov (KZK) type equation incorporating the thermal effects of the microbubble oscillations by introducing the energy equation proposed by Prosperetti [J. Fluid Mech. (1991)] into the set of basic equations based on mixture and two-fluid models. Moreover, the phase difference between the temperature gradient and the average temperature inside bubble is considered in the energy equation. As a result, we found that (i) the thermal conduction of gas inside bubbles strongly affects the dissipation of ultrasound and (ii) the phase difference affects the advection of ultrasound.
Extrapolation of Green's functions using the waveguide invariant theory
Authors: Song Hee-Chun , Byun Gihoon
Published: June 2021

The broadband interference structure of sound propagation in a waveguide can be described by the waveguide invariant, β, that manifests itself as striations in the frequency-range plane. At any given range (r) there is a striation pattern in frequency (ω), which is the Fourier transform of multipath impulse response (or Green's function). Moving to a different range (r+Δr), the same pattern is retained but either stretched or shrunken in ω in proportion to Δr, according to Δω/ω=β(Δr/r). The waveguide invariant property allows a time-domain Green's function observed at one location, g(r,t), to be extrapolated into adjacent ranges with a simple analytic relation: g(r+Δr, t) ≈ g(r,α(t-Δr/c)) where α = 1+β(Δr/r) and c is the nominal sound speed of 1500 m/s. The relationship is verified in terms of range variation of the eigenray arrival times via simulations and using real data from a ship of opportunity radiating broadband noise (200–900 Hz) in a shallow-water environment, where the steep-angle arrivals contributing to the acoustic field have β ≈ 0.92.
Long-term variations in calls produced by a potential blue whale species from the central Indian Ocean
Authors: Pinto Nikita R. , Chandrayadula Tarun K.
Published: June 2021

The Comprehensive Nuclear-Test-Ban Treaty Organization hydrophones at Diego Garcia record many marine mammal sounds from the central Indian Ocean. A peculiar call between 20 and 40 Hz from a potential blue whale species, referred to as the Diego Garcia Downsweep (DGD), is regularly recorded in the dataset. The call consists of a set of tones that resemble a comb, followed by a downsweep. Long term spectral averages suggest that the call frequencies are drifting. Tracking the change in frequencies by mere visual observations from the spectrograms is however challenging because of interference from anthropogenic noises and other biophony. This talk presents signal processing methods to track the call-frequencies, across years 2002 to 2019. Energy detectors are initially used to identify, and then exclude acoustic interference from shipping and outliers from electronics. Following that, to isolate the DGDs, and cancel other biophony, the presentation constructs subspace detectors. Finally, the talk uses the spectrograms of the detections to track the change in frequencies for each day. The observations show that while the frequencies of the comb steadily increase, the downsweep decrease. There are new frequencies that appear, and some disappear. These changes are unlike behavior observed from other whales in the region.
Visualizing how anthropogenic noise affects the Good Environmental Status of the North Sea
Authors: Griffiths Emily T. , Tougaard Jakob , de Jong Christ , Carder Michael , Andersson Mathias , Merchant Nathan D. , Fischer Jens-Georg , Kühnel Dennis , Norro Alain , Kinneging Niels A.
Published: June 2021

The Joint Monitoring Programme for Ambient Noise North Sea (JOMOPANS) aimed to develop a framework for managers, planners and other stakeholders to incorporate the effects of ambient noise in their Good Environmental Status (GES) assessment of the North Sea. This was accomplished by generating spatial maps of the anthropogenic and natural soundscapes, modelled from ambient noise measurements collected around the North Sea by the different member states in 2018 and 2019. We focused on the depth-averaged sound pressure level (SPL) of the one-third octave (base-10) bands between 10 Hz to 20 kHz in one second snapshots, viewed in monthly percentiles. From these data, we can better understand the criteria and noise thresholds necessary to achieve GES in the North Sea. Part of this effort was to develop a GES Tool, which would allow users to view the modelled noise maps by noise type (ship type, weather, etc.), protected areas designated by various EU agencies, and habitats used by soniferous or sound sensitive species. The tool computes and displays areas where there is a large overlap between anthropogenic noise and key marine species. This tool aims to help policy makers evaluate measures and thresholds put forward to achieve GES.
High-frequency single beam acoustical tweezers for 3D trapping and dynamic axial manipulation of cells and microparticles
Authors: Gong Zhixiong , Baudoin Michael
Published: June 2021

The 2D trapping and manipulation capabilities of acoustical tweezers based on focused acoustical vortices and Spiraling InterDigitated Transducers (S-IDTs) have been demonstrated both experimentally and numerically {see [Baudoin et al., Sci. Adv.5, eaav1967 (2019)] for microparticles and [Baudoin et al., Nat. Commun., 11, 4244 (2020)] for cells}. Compared to other technologies, S-IDTs have the advantage to enable the synthesis of high-frequency vortices with trap lateral extension comparable to the cell scale (typically from 5 to 20 μm), which is a necessary condition for selectivity. However, our previous work based on the S-IDTs only demonstrated 2D trapping. Here we investigate numerically the feasibility of 3D trapping of cells and microparticles with a focused vortex beam with large aperture and axial motion of the trapped object by tuning the excitation frequency. This work opens perspectives for 3D advanced cells and microparticles manipulation.
Utilizing laser distance sensors for audio recovery and acoustic source localization
Authors: Sarkar Kanad , Corey Ryan M. , Vuppala Sri , Singer Andrew C.
Published: June 2021

Previous research has shown that we can measure the acoustic displacement of a surface with a laser to recover audio inside a room, but these were not done with modern laser distance measurement methods. One such method, LIDAR, has the potential for acoustic recovery, allowing for a room's visual and auditory mapping to be done with one device. With audio recovery through an ideal spinning LIDAR, we would not only obtain the sound inside the room, but we should be able to localize an acoustic source through sampling points around a room. We define the parameters required for a single-point light distance sensor to record audio and compare our results to a light distance sensor used in manufacturing. We also show the parameters that a spinning LIDAR device needs for acoustic source localization and draw a comparison to what is currently available today.
Musical acoustics video demonstrations for online classes
Authors: Hartmann William
Published: June 2021

Forty high-resolution (3480 × 2160) video presentations were created in an attempt to replace in-person demonstrations for teaching elementary musical acoustics. Demonstrations were selected to accompany the author's textbook, Principles of Musical Acoustics (W. M. Hartmann, Springer, NY, 2013). Mean duration of the demonstrations was 4.1 min, though one was as long as 17 min while another lasted only 30 s. Demonstrations were devoted to physical principles of vibrations and waves (13), musical instruments and other sound making devices (20), and signal processing (3). Electronic instrumentation appeared somehow in almost all the demonstrations with (4) devoted specifically to instrumentation itself. Attempts were made to evaluate the effectiveness of the demonstrations through questions on the weekly quizzes. In any case, the demonstrations provided a welcome relief from a straightforward power-point lecture. A second form of relief presented some topics, especially mathematical topics, using pen and paper together with a document camera. Evaluations of the methods will be complete before the June meeting.
Aspects of teaching online during COVID-19 that I want to retain when returning to a “normal” classroom environment
Authors: Russell Daniel A.
Published: June 2021

For ten years I have been teaching graduate level acoustics courses simultaneously to 15–20 resident students and 20–25 distance education students. Prior to COVID-19, I live-streamed my lectures from a specially equipped multimedia classroom, but my attention during any given class period was primarily focused on the resident students sitting in the classroom. Any interaction with the 5–8 distance students attending my “live” lectures was limited to sporadic short questions posted to a chat window. During COVID-19, I have been teaching entirely online from my home and all 25-30 students (both resident and distance) who attend “live” class meetings participate in the same way: online through Zoom. As I reflect on 2.5 semesters of teaching acoustics to both resident and distant graduate students entirely online, there are several positive aspects of my online interactions with students that I hope to retain when I return to a “normal” classroom environment. In this presentation I will share several of the ways I successfully engaged and interacted with students while teaching online, both during and outside of class meetings. I will also discuss possible challenges of bringing some of those positive online interactions back into a “normal” classroom setting.
Sharing physics through sound: Undergraduate outreach
Authors: Fortener Holly , Conrad Brad
Published: June 2021

The Society of Physics Students values opportunities in physics and astronomy for undergraduates and places global science outreach for younger generations at its core. Science Outreach Catalyst Kits (SOCKs) are free to SPS chapters while supplies last and contain an exploratory physics and science activity. SOCKs are specifically designed for SPS chapters to use in outreach presentations for elementary, middle, and high school students. Each SOCK comes with the essential materials to conduct a set of demonstrations, a comprehensive manual, and instructions on how to expand the demonstration to become a tried-and-true outreach activity. The 2020–2021 SOCK celebrated the international year of sound by theming its demonstrations around acoustics and expanding availability to both SPS and Acoustic Society of America (ASA) chapters. Come learn about the 2020–2021 SOCK if you are interested in creating acoustic-themed demonstrations for ASA outreach events!
Making acoustics visible in the Philippines
Authors: Hermano Jose Francisco L. , Galan Martin C.
Published: June 2021

The Philippines presents itself as an ideal country to test methods of making acoustics visible in developing and underdeveloped countries. This report will first give a historical overview of the country’s acoustic environment in its 7000 + islands. 300 years of Spanish rule and 50 years of American colonial culture are acoustically visible in its public spaces, churches, buildings, schools and rural life. The first country in South East Asia to gain its independence, it is now a developing country that is the most fluent in the English language. It is known for its love for music and world class talents, onstage and backstage. It is presented that this gives the Filipino an inert advantage in understanding, expressing, good sound. Problems do abound, recent decades of economic strife have allowed the appreciation of good and safe sound to take a back seat. Lack of education, legislation, and the general misunderstanding of the basic principles of sound is the norm. The challenge of education and sharing the knowledge is urgent as the country progresses, so is the preservation of its rich multicultural acoustic heritage. Suggested solutions to remedy this will be presented.
More noise nuisance by Covid-19 Compared to 2019, the Dutch Noise Abatement Society (NSG) received 25% more questions about noise in 2020. These were mainly about living noises and environmental noise
Authors: Roelofsen Erik
Published: June 2021

Survey The NSG conducted a survey of more than 5,000 people and it was completed by some 1200 respondents aged 21 to 88 living across the country. This shows, among other things, that the noise from vehicles (road traffic) and aviation is perceived as significantly less present and noise from neighborhood and nature sounds as more present in the local noise landscape. Respondents perceived the composition of the sound as changed. Natural sounds and sounds from the immediate living environment are more pronounced than before the lockdown. Noise from vehicles, aviation and nightlife noise is perceived as considerably less. Because of the disappearance of the masking effect of these “unnatural” ambient sounds, nature and neighborhood noise came more to the foreground, as it were. Although a characterization / evaluation of the noise is not available before the lockdown, it may be assumed that respondents consider the acoustic environment on site to be more pleasant during the lockdown. Respondents perceive the noise situation as calm, calming, pleasant and pleasant. It can be assumed that the appreciation that many respondents gave to the noise during the lockdown is changing now that the old situation is returning.
Multiple scattering effects for polydisperse scatterers in soft media
Authors: Pinfield Valerie J. , Povey Megan J.
Published: June 2021

We explore the effects of polydispersity in 3D heterogeneous media consisting of scattering species (e.g., droplets, particles) in viscous liquids using a multiple scattering formulation to define effective speed and attenuation spectra. We adopt a published formulation [A. L. Gower, M. J. A. Smith, W. J. Parnell, and I. D. Abrahams, in Proceedings of the Royal Society of America (2018), p. 474] that rigorously extends multiple scattering theory to multi-component systems and show that in the long wavelength region it is consistent with a previous heuristic methodology applied to polydisperse scatterers. We investigate cases of a monomodal size distribution of finite width, and multi-modal size distributions with similar species. Further, systems of mixed scatterer species (i.e., different types of scatterer) with different sizes and distributions are considered. We will discuss the implications for inversion of ultrasonic spectra to determine particle size distributions and for the design of materials with targeted properties by varying composition (concentrations of different scatterer species) and scatterer properties.
Von Karman spatial correlation functions for modeling ultrasonic scattering in metallic media
Authors: Arguelles Andrea P.
Published: June 2021

In recent years, ultrasonic scattering has been studied as a potential method for nondestructive microstructure characterization in polycrystalline media. In order to invert microstructural data from ultrasonic data, analytical models of wave propagation and material statistics are generally employed. The microstructure statistics are frequently represented by spatial correlation functions (SCFs), which describe how microscopic variables at random positions are correlated (e.g., elastic stiffness). In polycrystalline media with statistically isometric crystallites, SCFs are defined as the probability that two randomly chosen points lie within a single crystallite (or grain). This work reviews common forms of the SCF in the context of ultrasonic scattering measurements. In addition, we introduce the von Karman SCF, frequently used in seismic wave propagation studies, as a potential alternative for metallic components with increased microstructural complexity. In the macroscale, the material systems are assumed to be statistically isotropic, and the microstructural differences focus on the morphology of the grain structure.
Agglomeration of particles by a converging ultrasound field and their quantitative assessments
Authors: Tang Tianquan , Huang Lixi
Published: June 2021

The acoustic radiation force resulting from acoustic waves has been extensively studied for the contact-free generation of organized patterns. Microscopic objects normally cluster at pressure nodes, but the size of the clusters is restricted by the saturation limit. Here, we present a two-dimensional bulk acoustic wave (BAW) device to propel particles of various sizes. It is shown experimentally that, when particles are large, significant acoustic energy is scattered and is partly absorbed by the matched layers in front of the sensors. The acoustic radiation force then forms a convergent acoustic pressure field which agglomerates the large polystyrene (PS) particles towards the central region instead of the pressure nodes. The transition from the nodal-array patterns to the central agglomeration depends on particle size, particle concentration, and load voltage. A parametric study reveals that the particles can agglomerate with a cluster ratio greater than 70%, and this ratio can be improved by increasing the load power/voltage supplied to the transducers. With its ability to perform biocompatible, label-free, and contact-free self-assembly, the device introduced offers a new possibility in the fabrication of colloidal layers, the recreation of tissue microstructure, the development of organoid spheroid cultures, the migration of microorganisms, and the assembly of bioprinting materials.
Phones in larger inventories are not (necessarily) less variable
Authors: Hauser Ivy
Published: June 2021

It is often assumed that there should be relatively less within-category phonetic variability in production in languages which have larger phonemic inventories (Lindblom, 1986 on Dispersion Theory). Although this hypothesis is intuitive, existing evidence in the literature is mixed and suggests the need to modulate the hypothesis according to phonological context (e.g., Renwick, 2012) and individual cues (Recasens and Espinosa, 2006). In this paper, we examine this prediction using data from sibilant fricatives in French, Polish, and Mandarin. A direct implementation of Lindblom (1986) predicts more variation in French (2 sibilants) relative to Polish and Mandarin (3 sibilants). We obtained data from these languages in a speech production experiment, analyzing within-category variability in sibilant center of gravity and onset of the second formant of the following vowel. We observed no language-specific differences in extent of within-category variability on either phonetic dimension. We did, however, observe systematic individual differences in extent of within-category variability among speakers of the same language, which were correlated with individual differences in production cue weight. We interpret these results as evidence that extent of variation is related to phonological contrast, but contrast must be quantified in terms of cue weight, rather than phoneme inventory size.
Labiodentalization of Korean bilabials
Authors: Kang Elisabeth , Purnomo Charissa , Wu Linda , Wang Melissa , Brady Alexandria , Purnomo Gracellia , Liu Yadong , Gick Bryan
Published: June 2021

The present study examines the interaction of Korean bilabials in natural speech during neutral and smiling conditions to determine whether labiodentalization occurs and, if it does, how the body resolves the conflict between lip spreading and lip compression in smiled speech. Results from various Korean YouTube videos indicate that despite the absence of labiodental tokens in the Korean language inventory, bilabial stops are compromised in smiled speech in being realized as labiodental tokens.
Acoustic analysis of an actively controlled pipe subject to vortex induced vibration
Authors: Li Hui , Cheer Jordan , Daley Stephen , Turnock Stephen
Published: June 2021

Pipe-like structures are utilised in a wide variety of engineering applications, which must often consider the impact of noise and vibration. This paper presents a numerical study into the Vortex Induced Vibration (VIV) of a flexible pipe in laminar flow and the resulting acoustic radiation, and explores the potential of an active vibration control strategy. The VIV is solved using a commercial CFD code, coupled with a finite element model (FEM) to obtain the pipe displacement. The hydrodynamic noise is solved using the FW-H equation based on the acoustic analogy and the vibrational noise is calculated by an acoustic FEM in the time-domain. Without control, when the vortex shedding frequency is approximately equal to the first structural natural frequency of the pipe, large amplitude vibration is induced. The fluid-pipe interaction causes hydrodynamic noise and the vibration of the pipe generates significant vibroacoustic noise. The simulations show that when the first mode of the pipe is well excited, the vibroacoustic noise dominates the sound radiation. A velocity feedback controller is then utilised to control the VIV of the pipe, which reduces both the vibrational and hydrodynamic noise, with the latter reduced to about the same level as a rigid stationary pipe.
What can you do with twenty years of water column sonar data? Plenty!
Authors: Jech J Michael
Published: June 2021

Collection of multifrequency fisheries acoustic data began at the NOAA Northeast Fisheries Science Center (NEFSC) in 1998. Over the past 20 + years, data have been collected on the NOAA fisheries survey vessels as well as commercial vessels during numerous surveys and research cruises. Many lessons in cooperation, initiative, persistence, and compromise have been learned, resulting in data sets with plenty of potential. Some of these data have been rejected and then resuscitated for stock assessments, used to estimate biomass of undersampled biota, and used to study catchability of commercial species. Until recently, data were limited to those at the NEFSC with sufficient expertise and access to the data—i.e., me, which has restricted application of the data. But now the data are searchable and available to the world via NOAA’s National Center for Environmental Information (NCEI). The evolution of acoustic technology and software from costly and proprietary to inexpensive and open-source has expanded the utility of these, and other long-term, data sets to the broader scientific community. An overarching goal has been to collect consistently high-quality data, yet only through incorporating innovation can long-term data collection survive in a dynamic environment and ever-changing scientific landscape.
Seasonal variations in multi-year active acoustic surveys of fish and zooplankton in the New York Bight
Authors: Lucca Brandyn M. , Blair Hannah , Warren Joseph
Published: June 2021

Active acoustic surveys provide fine-scale measurements over broad spatial and temporal scales of organism abundance in the water column which can be useful as ecosystem indicators. As part of a long-term time series monitoring program, we conducted seasonal surveys within the New York Bight beginning in 2017. The survey comprises eight transects that extend from near-shore to the continental shelf break, and include multiple stations within each transect where net tows and CTD casts are conducted. Acoustic backscatter measurements at 38, 70, 120, and 200 kHz from the water column were integrated (NASC, m2 nmi−2) to examine the distribution and relative abundance of pelagic scatterers. Generally, NASC was highest during the summer and fall surveys, which corresponds to expected seasonal migrations of fish and squid in this area. Winter NASC distributions were highest in waters deeper than 50 m, but increased nearshore during the summer and fall surveys. Backscatter also appeared to be associated with bathymetric features, such as the shelfbreak and the Hudson Canyon, and in some cases with hydrographic fronts and gradients. These data are the first steps in a longer-term monitoring program of pelagic organisms in the New York Bight.
Centralized repositories and cloud-based access: How ocean acoustic archives add value and enhance science
Authors: Wall Carrie , Anderson Charles , Martinez Veronica
Published: June 2021

The NOAA National Centers for Environmental Information has developed two ocean acoustic archives for long-term stewardship, discovery and access to water-column sonar and passive acoustic data. These vast datasets are collected across NOAA, other government agencies, and academia for a wide range of scientific objectives. Through free and global access, users can discover, query, and analyze the data for new research and add value to the data by using it beyond its original collection purpose. NCEI has partnered with Google and Amazon Web Services to facilitate cloud-based access to 200 + TB of archived ocean acoustic data. Users can listen to the sound files from their browser, immediately download the desired data, and—most importantly—bring processing routines to large volumes of data from simple statistical analyses to artificial intelligence. The strength of the archives, the challenges faced by the impending tsunami of data, and how to tap into the archives for current and future acoustic research will be discussed.
Echopype: Enhancing the interoperability and scalability of ocean sonar data processing
Authors: Lee Wu-Jung , Staneva Valentina , Mayorga Emilio , Nguyen Kavin , Satiewan Landung , Majeed Imran
Published: June 2021

The recent expanded availability of autonomous ocean sonar systems has created a data deluge. Despite their potential in advancing our understanding of the marine ecosystems, a large proportion of these new data remains significantly under-utilized. Specifically, the sheer tedium in data wrangling has significantly diverted efforts of the research community away from answering scientific questions. One of the root causes of this problem is the lack of an interoperable and scalable analysis workflow that adapts well with the rapidly increasing data volume and can be easily integrated with other oceanographic observations. To address this challenge, we developed an open-source software package “Echopype” that leverages the power of existing distributed computing libraries in the scientific Python ecosystem to directly interface data storage and computation on the cloud. Echopype provides tools to convert manufacturer-specific data files to a standardized, labeled multi-dimensional format that is familiar to the wider oceanography and geoscience communities, and offers a uniform computational interface for data originating from heterogeneous instrument sources. We envision that the continued development of Echopype will catalyze broader use of sonar data in oceanographic studies.
A Hybrid magnetic-ultrasonic technique for spectral viscoelastic characterization of soft solids
Authors: Tarazona Rafael , Cebrecos Alejandro , Jiménez Noé , Camarena Francisco
Published: June 2021

We present a hybrid technique that combines magnetic forces and ultrasonic waves (MMUS based) to explicitly characterize the complex elastic modulus of soft-solids in the frequency domain. The results show the dependence of the viscoelastic properties with the frequency content of the applied magnetic impulse.
Evaluation of H-scan imaging in phantoms and ex vivo tissue
Authors: Yadav Anushka
Published: June 2021

H-scan ultrasound imaging is a recently reported technique for tissue characterization. In this study, we report on the evaluation of H-scan imaging in hydrogel phantoms with scatterers of different sizes and in ex vivo tissue.
Computation of normal modes based on a coupled finite/infinite element formulation
Authors: Kronowetter Felix , Martin Eser , Baydoun Suhaib K.
Published: June 2021

The computation of eigenfrequencies and corresponding normal modes in exterior acoustic domains is presented based on a coupled finite/infinite element approach. First, the eigenvalue problem is solved in 2D elliptical domains. The applicability of normal modes is discussed in the example of sonic crystals. It can be shown that the sound-insulating effect of sonic crystals and individual meta-atoms in the free field can be related to certain normal modes in exterior acoustics. The numerical results provide a new point of view and physical insights into the effects and underlying physics of sound insulation by finite periodic sonic crystals and acoustic meta-atoms in the free field. Second, the quadratic eigenvalue problem of a hollow sphere submerged in water is addressed by a contour integral method based on resolvent moments. The accuracy of the proposed numerical framework is shown by comparing the eigenfrequencies to those obtained by boundary element discretization as well as ﬁnite element discretization in combination with perfectly matched layers. Extensive parameter studies demonstrate the performance of the method with regard to both projection and discretization parameters. The contour integral method is compared to the Rayleigh-Ritz procedure with second-order Krylov subspaces via the residuals of the computed eigenpairs.
An investigation of sound radiation from the double bass using acoustical holography
Authors: Bellows Samuel D. , Leishman Timothy W.
Published: June 2021

Studying radiation from musical instruments helps increase understanding and improve applications in auralizations, room acoustics, and microphone placement techniques. This work reviews a string bass's directivity measurements and demonstrates how numerical techniques such as spherical near-field acoustical holography enhance understanding of both the instrument's near-field and far-field radiation. The technique also allows calculation of the sound intensity field around the instrument, providing additional insights.
State-space simulation of sound source directivity for interactive geometric acoustics
Authors: Maestre Esteban , Scavone Gary , Smith Julius O.
Published: June 2021

A method is proposed for simulating the frequency-dependent directivity of sound sources for use in interactive geometric acoustic rendering applications. The method is based on using measurements to design a state-space filter allowing the interactive simulation of a time-varying number of radiated sound wavefronts, each towards a time-varying direction. With applicability in sound synthesis or auralization within virtual environments where sound sources dynamically change position and orientation, techniques are proposed for modeling and simulating directivity profiles on perceptually motivated warped frequency axes, along with alternatives for representing directivity on a per-vibration-mode basis or by reduced-order efficient representations. We demonstrate the method by using experimental acoustic data to simulate the directivity of a violin body and a clarinet air column.
Simulation of the propagation of classical and low booms through turbulent wind fluctuations
Authors: Leconte Roman , Chassaing Jean-Camille , Coulouvrat François , Marchiano Régis
Published: June 2021

The present revival of supersonic civil aviation outlines the need to study the propagation of sonic boom through turbulent wind fluctuations known to have an important impact on the noise perceived at the ground. Numerous physical phenomena must be considered: diffraction, non-linearity, absorption, relaxation and turbulence effects. A recent numerical method called FLHOWARD3D is used to simulate the propagation of classical and low-boom wave-forms in a three-dimensional domain of (1 km × 1 km × 1 km) representing a portion of the planetary boundary layer. Wind field is synthesized following a von Kármán energy spectrum. It is found that simulated wave-forms on the ground are close to experimental observations. Low-boom wave-forms show less sensitivity to turbulence. Comparisons between 2D and 3D simulations for peak overpressure statistical distribution show that, in 3D, results are closer to flight tests data than in 2D. Nevertheless the 2D levels are consistent with the experimental levels for around 98% of the cases, and only slightly underestimate the rarest events of highest amplification. Therefore, for this configuration, 2D simulations, though slightly less accurate than3D ones, are computationally much less intensive and can be used for statistical analysis. [This research was conducted as a part of Rumble—EU Grant Agreement 769896.]
Probability distributions of sonic boom noise metrics in isotropic turbulent fields
Authors: Carr Alexander N. , Lonzaga Joel B. , Miller Steven A.
Published: June 2021

Sonic boom waveform distortion caused by isotropic turbulence is examined with numerical simulations of acoustic propagation through randomly generated 3D turbulent fields. A recently developed planar, one way acoustic propagation code is used in this study to simulate the propagation of sonic boom waveforms. Computations of the signal account for diffraction, signal scattering by turbulence, nonlinear distortion, and absorption. Two types of waveforms are considered, one type is an N-wave and the other is a shaped boom. The intensity of the turbulent field is systematically varied for each set of simulations. For each condition, simulations through hundreds of randomly generated fields are conducted to obtain the statistical means and variances of PL, ISBAP, and select weighted SEL metrics. The computational results provide insight on the dependence of the probability distribution of each metric on the turbulence intensity and propagation distance. The data is further examined to compute probability density functions for each metric as a function of the turbulence intensity at different propagation distances. These functions provide insight on the effects of turbulence on the loudness levels of sonic booms. Future work and applicability of the results to atmospheric boundary layer turbulence is considered. [NASA Fellowship Activity Grant No. 80NSSC19K1685.]
An extension of the geometrical-acoustic model near a caustic with application to off-track sonic boom focusing
Authors: Wade Luke A. , Sparrow Victor W.
Published: June 2021

A focused sonic boom or “superboom” is caused by the convergence of acoustic energy generated by a passing supersonic aircraft; this occurs along a surface known as a caustic. The term “superboom” is fitting, as the resulting ground pressure signature is invariably louder than any other boom event associated with the given aircraft configuration. Unfortunately, when an aircraft accelerates to supersonic speeds, boom focusing is unavoidable. Although previous research has modeled the focus boom expected under the flight track, relatively little is known about noise experienced away from the flight track. The most popular model for sonic boom focusing, the lossy nonlinear Tricomi equation (LNTE), breaks down when an observer is not directly undertrack. This presentation will recount recent work aimed at augmenting the LNTE model such that it remains accurate over the lateral extent of the boom carpet during focusing. Emphasis will be placed on the extension of the geometrical-acoustic approximation used above the boundary layer of the caustic via analysis of new expressions resulting from the addition of the off-track component to the problem. [This material was based upon work supported by the National Aeronautics and Space Administration under Grant No. 80NSSC19K1684 issued through the NASA Fellowship Activity.]
Eye-movement patterns of hearing-impaired listeners measure comprehension of a multitalker conversation
Authors: Shiell Martha M , Cabella Teresa , Keidser Gitte , Niehorster Diederick C. , Nyström Marcus , Skoglund Martin , With Simon , Zaar Johannes , Rotger-Griful Sergi
Published: June 2021

The ability to understand speech in complex listening environments reflects an interaction of cognitive and sensory capacities that are difficult to capture with behavioural tests. The study of natural listening behaviours may lead to the development of new metrics that better reflect real-life communication abilities. To this end, we investigated the relationship between speech comprehension and eye-movements among hearing-impaired people in a challenging listening situation. While previous research has investigated the effect of background noise on listeners’ gaze patterns with single talkers, the effect of noise in multitalker conversations remains unknown. We tracked eye-movements of seven aided hearing-impaired adults while they viewed video recordings of two life-sized talkers engaged in an unscripted dialogue. Hearing loss ranged from moderate to severe. We used multiple-choice questions to measure participants’ comprehension of the conversation in multitalker babble noise at three different signal-to-noise ratios. All participants made saccades between the two talkers more frequently than the talkers’ conversational turns. This measure tended to correlate positively with participants’ comprehension scores, but the effect was significant in only one signal-to-noise ratio condition. Post-hoc investigation suggests that intertalker saccade rate is driven by an interaction of hearing ability and conversational turn-taking events, which will be further discussed.
The influence of spatially varying materials and buckling instabilities on elastic band gaps
Authors: Konarski Stephanie G. , Naify Christina J.
Published: June 2021

The behavior of band gaps is often important to the design of architected materials. One aspect of interest is the ability to tune the band gap via an external stimulus. The use of elastic deformation is a popular method within the field of mechanical metamaterials to achieve band gap switching. Another design feature is the width of the band gap. Structures with variations in the physical or geometric properties may exhibit wider band gaps than uniform designs. This work combines the study of lattices that achieve buckling induced band gaps with spatially varying material properties to leverage both effects. The example lattice design contains super-unit cells of circular voids within a soft elastomeric matrix arranged with different combinations of discrete material properties. The present numerical study compares the simulated transmission through several example designs and demonstrates both band gap widening due to the multiple materials and switching as a function of mechanical deformation.
Using remotely collected voice recordings for clinical voice evaluation: A feasibility study
Authors: Ishikawa Keiko , Mendes Clarion , Braden Grace , Libert Kelsey , Kouriabalis MariaElena , Yang Lianna J.
Published: June 2021

The COVID-19 pandemic underscored the importance of telepractice in the care of voice disorders. Acoustic analyses are routinely conducted for determining the presence and severity of voice disorders. In the in-person voice evaluation, the recording environment is carefully controlled as the recording's quality can affect the acoustic analyses' output. Telepractice environment does not allow such control, challenging this aspect of voice evaluation. In order to capture the nature of this challenge, this study examined the feasibility of using remotely collected voice recordings for the acoustic evaluation of disordered voice. Thirteen students in Vocal Performance and Theater studies were trained to perform individuals with voice disorders as standardized patients (SPs) and underwent a remote voice evaluation. Recordings of sustained vowels and sentences were collected via Zoom and the SP's personal computers. The fundamental frequency, cepstral peak prominence, and harmonic-to-noise ratio were calculated from these recordings. A listening experiment was also conducted to examine the perceptual similarity between the Zoom and computer recordings. The preliminary data analyses indicated that the mode of voice recording significantly affects the listener's perception and acoustic analyses of dysphonic voice. Clinical implications and possible strategies for future studies will be discussed.
Remotely collecting immediate voice production effects of semi-occluded vocal tract exercises
Authors: Ford David S. , Deliyski Dimitar
Published: June 2021

The purpose of this study was to evaluate the feasibility of remote collection of immediate vocal production effects of semi-occluded vocal tract exercises (SOVTs). Participants received a shipment of study equipment and materials with instructions on how to set-up and configure them. The collection protocol was conducted with remote guidance from the researcher via a Zoom session. The protocol included a double baseline voice recording, experimental tasks consisting of straw phonation and straw phonation into a cup of water, and a post-task recording. Audio recordings of sustained vowels, CAPE-V sentences, and the Rainbow Passage were analyzed for jitter, shimmer, harmonic-to-noise ratio, cepstral peak prominence, and presence of a singer’s formant. Following the tasks, participants were asked to provide self-perceptual ratings of vocal quality and vocal effort. Auditory-perceptual analysis (CAPE-V) was also performed, in which expert listeners (speech-language pathologists with extensive voice backgrounds) rated differences following the SOVT tasks. Instrumentation and methodology will be discussed, with a focus on the strengths and weaknesses of remote data collection including which voice assessment metrics were still robust to immediate SOVT effects, even in a remote setting. While obtaining lab-quality audio recordings for acoustic analysis remotely is considered challenging, this study suggests that it is feasible to obtain high-quality data remotely.
Sequential sparse Bayesian learning for beamforming
Authors: Park Yongsung , Meyer Florian , Gerstoft Peter
Published: June 2021

A sequential Bayesian method for beamforming is presented for the estimation of the directions of arrivals (DOAs) of source signals which are varying over time. The sparse Bayesian learning (SBL) uses prior information of unknown source amplitudes as a multi-variate Gaussian with zero-mean and time-varying variance parameters. For sequential processing, we utilize the unknown variance as statistical information across time and propose a sequential SBL-based method to improve time-varying DOA estimation performance. The suggested method has two steps. A prediction step calculates the prior distribution of the current variance parameter from the variance parameter estimated at the previous time step, and an update step incorporates the current measurements. This SBL approach with sequential processing provides high-resolution for time-varying DOA tracking. We evaluate the proposed method using simulated data and real data from the SWellEx-96 experiment.