bluuebunny/crossref_metadata_2025 huggingface dataset:
Active acoustic metamaterials with independently programmable bulk modulus and full mass density tensor
Authors: Kovacevich Dylan , Popa Bogdan-Ioan
Published: July 2024

Active acoustic metamaterials consist of unit cells with sensor-driver pairs that produce a coherent response to incident waves. The effective acoustic properties of the metamaterials depend on the gains programmed between the sensing and driving components. The strength of the monopole response to the local pressure determines the effective bulk modulus and the dipole response to the local particle velocity determines the effective mass density. The unit cells are controlled individually, so in theory the metamaterials can be scaled to an arbitrary size and geometry, but prior realizations were limited to only a few cells with 1D operation. Here, we present an active acoustic metamaterial of nine cells in 2D with programmable bulk modulus and mass density tensor. We demonstrate the ability to independently program the property components (bulk modulus and four mass density elements) for any desired set within stable limits, including previously unattainable acoustic properties necessary for the fabrication of transformation acoustics devices. We also demonstrate complex effective properties, specifically a lossy layer with impedance matched to the background, such that incident waves are absorbed with no reflection. The effective properties of the active metamaterial are validated by comparing the experimental total and scattered fields to ideal simulation results.
Artificial data augmentation using braided human features for underwater acoustics
Authors: Sen Gupta Ananya , Christensen Andrew J. , Mathews Anjali , Das Subhajit , Kirsteins Ivars P.
Published: July 2024

Underwater acoustics datasets provide rich environmental information that can potentially be mined using popular machine learning architectures. However, such knowledge discovery is typically limited by the high feature uncertainty, lack of robust ground truths, limited availability of public-domain data, and difficulty of reproducing experimental conditions in field experiments. This poses a data science challenge to study persistent target features, as they can only be learnt and classified robustly if large scale robust training and testing datasets are available. This “nano-data” problem can be potentially solved by augmenting the training and testing data repositories with a two-pronged approach: (i) physics-driven simulations of desired features, which offer interpretable ground truths but typically cannot emulate practical open-sea experiments; (ii) geometric-proxy augmentation using creatively constructed non-domain datasets that emulate the desired feature geometries and environmental effects. For example, a skilled dancer can emulate specific features geometries through geometric contortions of the human body. Such choreographed dance movements can be reproduced reliably against different types of stage environments, structured and unstructured, to emulate the oceanic environment under different conditions. We will present preliminary results in data augmentation from both approaches and discuss the trade-offs between physics-oriented simulations and geometry-driven proxy augmentation. [ONR grant N000142312503.]
Acoustic monitoring of marine environmental quality: An example from the Estuary and Gulf of St. Lawrence
Authors: Aulanier Florian J. , Simard Yvan , Juif Clément , Giard Samuel
Published: July 2024

As a part of the Canada’s Ocean Protection Plan, Fisheries and Oceans Canada has joined the efforts to better understand and monitor the effects of anthropogenic noise on marine environmental quality. Since 2017, underwater acoustic observatories were put in place across endangered whale habitats leading to the acquisition of big underwater acoustic dataset to process and analyze. In the Estuary and Gulf of St. Lawrence, underwater noise has been continuously monitored at 13 locations (6 to 10 simultaneously) between 2018 and 2023 at sampling rate up to 256 ksps in order to better understand the effect of shipping noise on marine environmental quality of the endangered St. Lawrence estuary beluga habitat. In this presentation, the data analysis pipeline from in situ sampling to processing is detailed, including recording schemes, data quality and control, soundscape cube, source separation, multi-scale statistics on noise levels and risk of impacts on habitat quality and visualization. These steps are used to identify, characterize and quantify daily to interannual spectral variability of underwater noise and their relationship with local environmental forcings such as shipping, wind, ice, tides, and currents at targeted locations. Ultimately, these results are used to provide support to (1) marine conservation and spatial planning initiatives from DFO and the Saguenay St. Lawrence Marine Parc; and (2) assess the predictability power of the outputs of soundscape modeling.
Focused ultrasound pulse repetition frequency impacts bubble activity and tracer delivery during blood-brain barrier opening
Authors: Fletcher Stecia-Marie , Chisholm Amanda , Zhang Yongzhi , McDannold Nathan J.
Published: July 2024

The impact of pulse repetition frequency (PRF) on microbubble activity and blood-brain barrier (BBB) opening, for a fixed total number of pulses, is unclear. We studied bubble response to a range of PRFs (0.125, 0.25, 0.5, 1, and 2 Hz) by monitoring bubble emissions during focused ultrasound (FUS) sonications of the rat brain (274.3 kHz). When a location was treated with a test PRF and a control PRF of 1 Hz, at the same pressure, the change in the harmonic amplitude compared to the control decreased with increasing PRF, with a median change of 73.8% at 0.125 Hz and −38.3% at 2 Hz. Significant changes were not observed with repeated sonications at the same PRF. Furthermore, between PRFs of 0.25 and 1 Hz, no difference was observed in the threshold for broadband emissions, which are linked to the potential for tissue damage. Fluorescence imaging was used to estimate the concentration of Trypan Blue (TB) dye following a fixed-pressure 75-pulse exposure for PRFs of 1 and 0.25 Hz in rats. A 0.25 Hz PRF led to a 68.2% increase in the mean concentration measured at the target, with a 53.9% increase in the mean harmonic sum compared with a 1 Hz PRF. Finally, a harmonic emissions-based controller at a PRF of 0.25 Hz yielded similar TB delivery, with fewer instances of petechiae observed through histology, compared to the same controller at 1 Hz. These results may be adapted to improve the clinical safety margin of FUS-mediated BBB opening and to improve the sensitivity to detecting small harmonic signals from cavitating microbubbles.
Miniaturized acoustic concentrators for ultrafast 3D ultrasound imaging
Authors: Touré Ibrahima , Bilodeau Maxime , Quaegebeur Nicolas
Published: July 2024

Ultrafast 3D ultrasound imaging is a rapidly growing research field that enables real-time imaging at a high frame rate and in a non-invasive manner. Currently, to achieve ultrafast 3D ultrasound, plane or diverging waves from virtual sources are used. These virtual sources can be considered as focal points during emission, allowing for improved transmission of ultrasonic energy. However, they have limitations in terms of transmitted energy, complex electronics, and timing issues, which impact the quality of the resulting images. To address this, a study was conducted to design and experiment with new miniaturized ultrasound transmitters based on cylindrical waveguides with tapered sections. These transmitters, with a diameter of approximately 100 μm, can replace the virtual sources. A numerical study based on 2D axisymmetric Finite Element Modeling (FEM) is first performed to model the transmission and reflection of longitudinal ultrasonic waves through various cylindrical rods. The results demonstrated that the transmission depends on the diameter ratio, frequency and longitudinal mode order (L0, L1, L2, etc.). An experimental study is then conducted on a stainless steel waveguide instrumented with 6mm piezo discs. The mechanical energy, estimated using Laser Doppler Vibrometer is transmitted through a 150 μm diameter rod, allowing mechananical focusing in the frequency range between 0.5 and 5 MHz. The application of this method to separate emission/reception transducers is then demonstrated for 3D ultrafast imaging.
Blind source extraction using Kronecker product structured mixing model
Authors: Koldovský Zbyněk , Čmejla Jaroslav , Farooq Aamir
Published: July 2024

Blind Source Extraction (BSE) aims at extracting a source-of-interest (SOI) from a mixture of signals observed through multiple sensors. In this work, we consider a parameter-reduced mixing model suitable for sensor arrays structured in a grid. The parameter vector involving weights with which the sensors receive the SOI is factorized into the Kronecker product of two sub-vectors. In addition to the description of the new model, we present an algorithm designed to identify the mixing parameters based on the assumption of independence of the SOI from the other signals in the mixture. In simulations, the performance of the algorithm is compared with that of the fully parameterized counterpart and is compared with the corresponding Cramer-Rao-induced bounds on the achievable Interference-to-Signal Ratio.
Modeling high-frequency backscattering from an impedance surface using Kirchhoff approximation
Authors: Chen Pei-Tai
Published: July 2024

The Kirchhoff approximation is based on planar wave impinging on a planar surface, which is approximated for high-frequency wave scattering from a curved object. The Kirchhoff approximation is used to assess backscattering from a curved, rigid surface when exposed to high-frequency incident waves. In this presentation, we expand the rigid surface Kirchhoff approximation to accommodate impedance surfaces. The derivation is performed on a planar wave’s incident onto an impedance flat surface, resulting in a reflection coefficient, which in turn determines both surface pressure and surface normal velocity. When these two surface quantities are integrated into a Helmholtz integral formula, it allows for the evaluation of backscattering acoustic field pressures. The BeTTSi model, featuring an impedance surface, serves as an illustration for comparing the current Kirchhoff approximation with the solution obtained by a Fast Multipole Expansion Boundary Element Method (FMBEM). The latter is a numerical solution of the corresponding Helmholtz surface integral equation. The numerical discretization involves nearly a million points, representing the degrees of freedom necessary for modeling the BeTTSi under high-frequency incident waves. The comparison involves these two numerical evaluations across various incident wave directions, encompassing scenarios with single reflection and multiple reflections due to surface geometry.
Comparison of substructuring methods with interface reduction
Authors: Luu Matthew , Young Jon , Wixom Andrew S.
Published: July 2024

For complex dynamical systems, substructuring techniques can be applied to simulate the large system more efficiently by handling it as a collection of smaller components. In order to couple these components, the description of the interface between components is very important. Classic substructuring techniques, such as the Craig-Bampton method, reduce the interior modes of the system, but don’t reduce the interface description. This can cause unnecessary degrees of freedom kept in the final assembled model. While there have been a few substructuring methods published that do include some amount of interface reduction, they are much more rare and even more rarely applied in practice. Therefore, the goal of this work is to survey these techniques and compare them with a new, line-based orthogonal polynomial interface reduction technique. These methods will be applied to a set of example problems in order to determine their validity and convergence compared to the full model.
An overview of symmetry-based techniques used for sound power application with illustrative case studies
Authors: Bacon Ian C. , Shepherd Micah , Sommerfeldt Scott D.
Published: July 2024

This work investigates the growing application of vibration-based sound power (VBSP) measurements in structural acoustics. The VBSP method involves multiplying a measured velocity vector by a geometry-dependent radiation resistance matrix to compute the frequency-dependent sound power. However, computational challenges arise during matrix construction, even for simple geometries. To address this, inherent symmetries in the radiation resistance matrix for both baffled and unbaffled geometries are exploited. Multi-layered Toeplitz symmetries emerge for baffled conditions, while centrosymmetric symmetries are manifest for unbaffled conditions. These symmetries enable an efficient compression and subsequent reconstruction of the resistance matrix. Simple case studies demonstrating the temporal costs for flat, curved, and arbitrarily curved plates in unbaffled conditions will be presented. [Funding for this work was partially provided by the National Science Foundation (NSF).]
Further development of high-amplitude underwater sound sources at The University of Texas Applied Research Laboratories
Authors: McNeese Andrew R. , Wilson Preston S. , Lee Kevin M.
Published: July 2024

Following the early research on the Combustive Sound Source (CSS), described in the previous talk, additional development occurred in the 2000’s and beyond, which included work on both the CSS and a new source, the Rupture Induced Underwater Sound Source (RIUSS). Development of the CSS in this era included maximizing the output of the source, investigating the use of CSS in arrays, and towing the source. The CSS was also deployed in surveys conducted during Shallow Water ’06 and the Seabed Characterization Experiment. In part due to lessons learned during those surveys, the RIUSS was conceived and developed. The RIUSS functions by placing a rupture disk over an evacuated chamber and mechanically breaking the disk (either by striking on demand or via hydrostatic pressure) at a specified depth to initiate a volume collapse that produces an impulsive acoustic waveform. The development and use of each sound source will be provided along with high-speed underwater video, examples of signatures, and examples of the efficacy of the sources in ocean acoustics research. [Work Supported by ONR and NAVO].
Controls on the acoustic expression of buried and surface chemical explosions
Authors: Bowman Daniel , Bal Amrit K. , Dannemann Dugick Fransiska
Published: July 2024

Surface and buried chemical explosions in the 1-50 ton TNT equivalent range can generate acoustic waves capable of traveling thousands of kilometers. Planned explosive campaigns in this size range have been used to develop acoustics-based yield determination techniques, investigate how acoustic propagation paths vary over short time scales, and examine how ground motion induces sound above the epicenter, among others. Here, we describe several test campaigns involving buried and surface chemical explosions. We discuss the combinations of explosive yield and burial depth that produce laterally propagating infrasound waves, as well as instances where diffuse sound from violent topographic shaking is observed. We also give an overview of a test series specifically aimed at investigating acoustic signal variation at tens to hundreds of kilometers range using co-located surface explosions fired tens of seconds apart. This will provide context for acoustic data interpretation from existing test series and aid in the design of future ones. [SNL is managed and operated by NTESS under DOE NNSA Contract No. DE-NA0003525.]
Resonators in free reed instruments: Good, bad, and unusual effects
Authors: Cottingham James P.
Published: July 2024

Western free reed instruments such as the accordion and the harmonica do not typically use pipe resonators. Yet even without pipes there are two sorts of resonators employed. In the case of mouth blown instruments, free-reed or not, the resonances of the players vocal tract are quite significant. Less often recognized as resonators are the reed chambers necessary to provide a secure mounting for the reed and to properly direct the airstream. The acoustical properties of these may or may not be beneficial. Because of their different reed construction, the Asian free-reed mouth organs require pipe resonators in to function. This paper will present examples of ways in which reed chamber and pipe resonances can enhance or interfere with tone production, as well as some interesting special effects produced by intentional mismatches between reed and resonator.
A psychoacoustic test on the effect of masking on annoyance to urban air mobility vehicle noise
Authors: Boucher Matthew , Christian Andrew , Tracy Tyler , Krishnamurthy Siddhartha , Shepherd Kevin , Begault Durand , Rizzi Stephen A.
Published: July 2024

Urban Air Mobility (UAM) vehicles have a large range of designs and configurations that lead to new noise characteristics and potentially different perceptual responses when compared to traditional aircraft. In addition, UAM vehicles are expected to operate around and within densely populated regions where the presence of ambient background noise is often present. Strategically, this can be leveraged to inform vehicle design and operations to partially or completely mask UAM noise, allowing for mitigation of negative responses and an increased number of allowed operations. A psychoacoustic test was conducted to investigate how masking effects can influence the annoyance response to a low frequency harmonic tone complex (80-320 Hz). To do this, five test subjects compared their annoyance response to the low frequency tonal noise with a higher frequency broadband noise (10 dB down bandwidth between 300 and 2000 Hz), with and without a masking noise present. Detection thresholds were also measured for both sounds to help fit a model to the data. Although the effect of masking on annoyance is complex, results indicate that for some individuals, masking leads to a lower annoyance than the sound level alone would predict.
The 1952 Ph.D. dissertation of T.F.W. Embleton on nonlinear acoustic propagation and reflection
Authors: Sparrow Victor W.
Published: July 2024

In his doctoral research Tony Embleton studied nonlinear acoustics experimentally using techniques available in the Physics Department of Imperial College, University of London. Originally developed by V. Timbrell, the interferometric equipment was substantially improved by Tony Embleton, enabling his Ph.D. findings. Studying propagation in a tube and reflection by both closed and open ends, Tony Embleton was able to substantially confirm the theory of the time, developed by Stokes, Earnshaw, Rankine, Rayleigh, and Taylor, many pieces confirmed for the first time. He also found discrepancies regarding the attenuation coefficients regarding the first and second half cycle of each pulse as well as a shortening of a pulse at reflection from a closed end. These findings are still worthy of further investigation. The results of reflection of pulses from the open end of a tube, forming a pressure release boundary condition, still are very interesting to the present author. A pulse propagating toward the open end steepens, but the reflected wave “unsteepens” which is a unique nonlinear acoustic phenomenon. [Work supported by the Penn State College of Engineering and its United Technologies Corporation Professorship.]
Characterization of effective elastic constants and anisotropy directions for Wire Arc Additive Manufactured steel samples using RUS
Authors: Le Bourdais Florian , Gardahaut Audrey , Leymarie Nicolas
Published: July 2024

In recent years, Resonant Ultrasound Spectroscopy (RUS) has been extensively applied to objects produced by additive manufacturing to characterize elastic material properties, detect defects or geometrical deviations. In this talk, we analyze samples that were produced using the wire-arc additive manufacturing (WAAM) process using different grades of steel wires. Resonance spectra were obtained and allowed to classify samples as either elastically isotropic or anisotropic. Detailed investigation on anisotropic samples (produced with 316L wire) under an orthotropy hypothesis showed that the samples were markedly softer along the layer deposition direction. Subsequent investigation using EBSD confirmed the results obtained with RUS. They also allowed to quantitatively model the elastic constants using the Voigt-Reuss-Hill averaging theory, which were in good agreement with the ones obtained using the RUS inverse problem.
Enabling resonant ultrasound spectroscopy in extreme environments
Authors: Mizzi Christopher A. , Maiorov Boris
Published: July 2024

Elastic moduli are fundamental thermodynamic susceptibilities that connect to thermodynamics, electronic structure, and mechanic properties. Thus, determining the changes of elastic moduli as a function of time or temperature is a powerful tool to study several thermodynamic and materials phenomena. Resonant Ultrasound Spectroscopy (RUS) determines elastic constants with high accuracy and precision from a single measurement of the mechanical resonances of a sample. Conventionally, the quantitative extraction of elastic moduli with RUS assumes free boundary conditions but lead to unstable positioning of the sample making it incompatible with extreme environments like high magnetic fields. In practice, even holding the sample produces contact forces that deviate from free-boundary conditions shifting resonant frequencies. In this talk, we show that, we can reduce the free-boundary conditions (by gluing/adhering the sample to the transducer), while still being able to obtain the full elastic tensor by a simple model of the sample-transducer interaction. This means elastic constants can be determined to within the uncertainty of conventional RUS, but with significant improvements in sample stability and control of sample orientation. We show the results of studying of several magnetic and structural phase-transitions using this new method.
A spatial digit task for assessing binaural function in individuals with hearing loss
Authors: Brungart Douglas , Davidson Alyssa , Clark Kelli , Perry Trevor T.
Published: July 2024

Spatial hearing is crucial in occupational tasks, yet until 2019, US Army fitness-for-duty requirements only considered hearing thresholds in the better ear. The regulation change introduced the Military Operational Hearing Test (MOHT) for those with worse-ear thresholds exceeding 40 dB HL at 0.5 or 1 kHz, or 60 dB HL at 2 kHz. This led to the development of the Spatial Digit Test (SDT) to assess binaural function in individuals with poor hearing in one ear but sufficiently good hearing in the other ear to pass a speech-in-noise test. The SDT involves digit pairs presented with Interaural Time Delays (ITDs) of +/−800 μs. Two studies were conducted: a validation study with over 200 individuals, and a verification study with more than 130 undergoing MOHT exams. Results show that individuals with normal auditory thresholds perform very well on the SDT, with about 95% correctly identifying at least 8 digits and 75% correctly identifying all 10. In contrast, only about 50% of individuals with monaural losses who took the SDT as part of the MOHT identified 8 or more digits. Results of the SDT were correlated both with subjective hearing complaints and with the Binaural Masking Level Difference. In conclusion, the SDT proves valuable for identifying individuals struggling using ITD cues to segregate and localize simultaneously presented speech signals.
Relation between spatial release from informational masking and localization discrimination
Authors: Zobel Benjamin H. , Zurek Patrick , Buss Emily , Freyman Richard
Published: July 2024

Spatial release from masking (SRM) occurs when a signal of interest (target) and an interfering sound (masker) come from different locations in space. SRM and sound localization are assumed to share common mechanisms, but it is still unclear whether SRM actually depends on hearing the target and masker in different places, even in situations dominated by informational masking. The current study used a spatial rhythmic release from masking (RMR) task [J. Middlebrooks and Z. Onsan, JASA, 132, 3896–3911, 2012]. The target and masker were trains of non-simultaneous noise bursts; hearing the target temporal pattern relies on segregation from the masker, which is supported by spatial separation. Using a headphone simulation of space (HRTFs), the current study replicated key aspects of Middlebrooks and Onsan’s (2012) finding that RMR spatial thresholds were poorer for high-frequency than low-frequency bursts. We investigated whether this low/high frequency difference, and others created with degraded localization cues, were associated with variations in basic localization discrimination tasks using the same RMR stimuli. Data collection is ongoing, but preliminary results suggest a covariation of spatial release in the RMR task and sensitivity to change in spatial angle. [Work supported by NIDCD R01-01625.]
Relationship between objective measures and listener intelligibility of speech processed by source-separation algorithms
Authors: Payton Karen L. , Goldhor Richard , Dousti Behdad , Dugan Sarah , Boyce Suzanne , MacAuslan Joel
Published: July 2024

A major determinant of success for separating a speech signal from a noisy environment is the intelligibility of the extracted speech signal. Intelligibility is best measured as the fraction of words correctly recognized by listeners, but computational measures are often preferred because they are less labor-intensive than collecting listener judgements. We compare listener intelligibility data to three acoustically derived measures: (a) SNRs estimated from the processed mixtures, (b) coherence and (c) speech-based Speech Transmission Index (sSTI). Sentences were recorded against restaurant babble, white Gaussian noise, and nonstationary noise by four microphones at different SNRs ranging from +4 dB to −8 dB. Processing conditions included (1) the original mixture; (2) the mixture processed by a critically determined 4-channel blind source separation (BSS) algorithm; (3) the mixture processed by a 2-channel, underdetermined, BSS algorithm; (4) the residual after subtracting noise estimates determined using a least-mean squared (LMS) algorithm; (5) an estimate of speech extracted using an LMS algorithm to remove the two noises and then 2-channel BSS to separate the sentences from the babble; and (6) pristine speech recorded with no noise. The computational measures are compared to gold-standard intelligibility results from listening tests.
Harmony in transition: Exploring the perception-production relationship in sound change
Authors: Kpogo Felix
Published: July 2024

This study investigates the perception-production dynamics of [æ] and [e] in an ongoing merger in Asante Twi’s Advanced Tongue Root (ATR) harmony system. Traditional descriptions state that [-ATR] /a/ is realized as [+ATR] [æ] before [+ATR] vowels /i, u, o/. Yet, recent acoustic evidence points to an ongoing sound change in different Twi-speaking communities: in contrast to traditional (rural/suburban) Twi speakers, urban speakers raise and merge [æ] with phonemic /e/ before /i, u/, a change that is more advanced in men and younger speakers (Kpogo, 2023). The present study aims to ascertain whether merger in production correlates with perceptual merger among the same participants in Kpogo (2023). Data from a forced-choice identification task suggests that the presence of a perceptual merger is associated with the participant’s locality. Traditional participants consistently identified [æ] and [e] correctly, suggesting separate mental representations for these vowels. Conversely, urban participants often perceived [æ] as [e], suggesting less distinct representations influenced by their own production. Concerning the perception-production relationship, evidence of a link was observed across localities but, crucially, not within each locality. This study contributes to theoretical discussions on the perception-production relationship during sound change, hinting at a co-evolving link between the two modalities.
Binaural fusion and vowel perception in cochlear implant users
Authors: Pierre Kayla , Reiss Lina A.
Published: July 2024

Excess binaural fusion can be a problem, especially in noisy environments when speech from multiple talkers are fused together. Previously, we showed that hearing aid users experience abnormally broad binaural fusion that leads to fusion and averaging of dichotic vowels of fundamental frequency (F0) differing by up to 1 octave (Reiss and Molis 2021). This study investigated whether cochlear implant (CI) listeners also experience abnormal fusion and averaging of double vowels in the free field. Six adult CI users (4 females) and four NH adults (1 female) were tested. Stimuli were synthetic vowels/æ/, /a/, /u/ and /i/, at F0 = 106.9, 151.2, and 201.8 Hz. Two different vowels were presented simultaneously from two loudspeakers at ±60°, with same or different F0. Subjects were instructed to select which one or two vowels they perceived. When ΔF0 = 0, NH and CI users often fused and identified only one vowel. As ΔF0 increased, NH listeners increased identification of two vowels, while CI users continued to fuse vowels. The findings show that in realistic free field listening conditions, CI users can experience excess fusion of multiple vowels of differing F0s, presenting additional challenges in noisy listening environments. [Work supported by NIH R01DC013307 and ASA SUREIA program.]
Balancing ensemble averaging and signal stationarity when processing acoustic data recorded during a rocket launch
Authors: Cunningham Carson F. , Shepherd Micah , Gee Kent L.
Published: July 2024

There are many important details to consider when collecting acoustical data during a rocket launch including system noise floor, dynamic range and transducer sensitivity. In this talk, the choice of signal processing parameters will also be shown to be important. Since the pressures are created by turbulence, ensemble averaging is key to reducing random variation. As such, the use of a Hanning window with 50% overlap would be customary for performing this type of processing. However, as the rocket lifts off, the source location moves, and the data can only be considered stationary for short blocks of time. Therefore, the ability to average is limited by non-stationarity. To balance these competing phenomena, an adjustable windowing function such as the Tukey window may be more appropriate than Hanning. Noise data collected at two different launches will be used to compare of the Hanning window with 50% overlap to that using of the Tukey window with a taper of α = 0.25, which filters 12.5% of the signal at each extremity, with 87.5% overlap. The use of both window types will be compared when estimating auto spectral densities and integrated overall levels. The effect of blocksize will also be determined.
Model manifold of transmission loss from a Pekeris waveguide using VGS parameters
Authors: Wang Michelle , Neilsen Tracianne B. , Transtrum Mark K.
Published: July 2024

In geoacoustic inversion, selecting an appropriate seabed parametrization, especially with an unknown number of sediment layers, is a challenge that is compounded by potential bias when establishing bounds in the parameter search space. One approach to addressing these issues is rooted in the techniques of Information Geometry. Information Geometry informs model selection and parameterization by quantifying which model parameters are informed by observational data. This paper provides an information geometric analysis of the Pekeris waveguide, where the acoustic properties of the lower half-space are derived from the viscous grain-shearing (VGS) model. Specifically, we consider single frequency transmission loss (TL) across a wide range of VGS parameters. By exploring the limits and boundaries of the geometric manifolds, particularly as parameters approach both low and high extremes, this approach provides indications of parameter hierarchies and correlations. Results will include slices of the model manifold and an evaluation of the boundary structure, providing insight into the relative impact of VGS parameters and the delineation of limiting regions. In doing so, this paper seeks to inform model selection and parameterization in geoacoustic inversion studies. [Work supported by the Office of Naval Research. Grant N00014-21-S-B001.]
A T-matrix approach to wave propagation and scattering in layered environments with rough interfaces
Authors: Ivakin Anatoliy N.
Published: July 2024

Wave propagation and interactions at the interfaces of multi-layered media can be described in terms of transition matrix coefficients, or T- matrixes, taken from solutions for a plane wave transformation, reflection, scattering, and transmission, at an interface between two homogeneous half- spaces. These solutions can be found separately for each interface of the layered system and each combination of adjacent media. Then scattering amplitudes or the T-matrix of the whole multi-layered system can be obtained using an iterative procedure that starts from a simple case of two half-spaces at the basement of the system. A quite similar iterative procedure is frequently used for calculating the reflection coefficient of compressional plane waves for a multi-layered fluid system with flat interfaces using the reflection coefficients of each interface. In this paper, we show that a similar, but a more general T-matrix approach, can be developed to include interface roughness, different types of media and waves, for instance fluid, elastic or poroelastic layers, compressional and shear waves (vertically and horizontally polarized). As an example, scattering from a rough elastic layer is considered. An explicit first-order expression for the scattering strength is obtained and it’s applications to remote sensing of sea ice layer are discussed. [Work supported by ONR.]
Simulation of acoustical parameters of churches in a virtual acoustics laboratory
Authors: Grazioli Gianluca , Gozzi Andrea
Published: July 2024

Current ISO standards for acoustical assessment limit the use of traditional mono-dimensional microphones for measuring equipment. However, microphone arrays offer more accurate spatial information compared to traditional microphones. This presents an opportunity to enhance research on architectural acoustics and preserve the acoustics of cultural heritage more effectively. Furthermore, modern recording studios equipped with virtual acoustics systems allow for the integration of spatial room impulse responses. This enables real-time auralization in controlled environments and enhances the overall immersive audio experience for users and musicians. This paper analyzes the main acoustical parameters obtained from spatial impulse responses captured in churches using various ambisonic microphones and inserted into a controlled, interactive, and immersive virtual acoustics system. The captured spatial acoustic measurements are then reproduced and evaluated in a virtual acoustics laboratory to identify any discrepancies between real and virtual spaces.
Towards a better understanding of multimodal integration and sensorimotor adaptation to audiovisual environmental incongruence using Virtual Reality
Authors: Zhang Xinyi , Shamei Arian , Grond Florian , Verduyckt Ingrid , Bouserhal Rachel
Published: July 2024

People use previous knowledge and in situ judgment to produce speech with a vocal effort appropriate to a given environment’s acoustics. To test how people integrate auditory and visual cues in speech production, we employed a three-by-three cross-conditional audiovisual match-mismatch paradigm. Three visually distinct environments with three different room acoustics were selected: a gymnasium, a classroom, and a hemi-anechoic room. The visual environment was presented with a Virtual Reality (VR) headset and the auditory environment was a diffuse room impression, playing back the participants’ speech through loudspeakers in the room with different reverberation times. Participants were prompted to speak in all nine combinations of the audiovisual conditions, with three being congruent and six incongruent. Linear mixed-effects regression modeling was used to evaluate the effect of the audiovisual manipulations and time course on mean intensity. Preliminary results indicate that participants initially spoke at a level that matched the visual expectation and then adapted to the audio condition; detailed analysis of the time course of adaptation is ongoing and will be presented. This study furthers our understanding of multimodal integration and the sensorimotor adaptation of speech production, which finds applications in fields including communication in noise and VR soundscape design.
Unidentified fish sounds as indicators of coral reef health and comparison to other acoustic methods
Authors: Jarriel Sierra , Formel Nathan , Ferguson Sophie R. , Jensen Frants H. , Apprill Amy , Mooney T. Aran , Parsons Miles J. , Di Iorio Lucia
Published: July 2024

As biodiversity hotspots, coral reefs are rich with sound cues. Monitoring these soundscapes for changes is essential as coral reefs decline around the world rapidly. Despite this, acoustic metrics that reliably represent reef health are still debated, and ground-truthing of methods are limited. We sought to investigate the occurrence and prevalence of fish sounds in relation to reef health, providing a foundation to compare assessment methods. We first quantified fish call rates for three U.S. Virgin Islands reefs exhibiting different community assemblages, by manually annotating fish calls across 8 days per site. Call rates were then compared with traditional visual surveys, and several acoustic methods commonly used in underwater soundscape research. Manually detected fish call rates successfully differentiated between the three reefs, capturing variation in crepuscular activity levels and predicting hard coral cover, fish abundance, and fish species richness. Meanwhile, most acoustic indices failed to parse out fine distinctions among the three sites, although sound pressure level showed the greatest correlation to call rates. Development of methods to improve the utilization of unknown fish sounds, such as automatic detection and classification tools, supports global sound library efforts and is essential to implement large-scale passive acoustic monitoring of coral reefs.
Passive acoustic monitoring of tropical and temperate reefs reveals ambient noise cycles on multiple time scales
Authors: Freeman Lauren , Duane Daniel , Rooney Ian
Published: July 2024

Passive acoustic monitoring programs of tropical and temperate reefs in Hawaii, Bermuda, and New England have been underway for several years using omni-directional recorders placed near shallow reef sites. These multi-year time scale datasets allow us to observe not only diurnal cycles that are becoming a familiar facet of biological soundscapes, but seasonal, lunar, and inter-annual variability driven by light and sea surface temperature. Coupling acoustic data collections with non-acoustic validation such as in situ video and oceanographic measurements offers additional insights as to what is driving variability and increasingly predictable patterns in biological ambient noise in littoral settings. This overview will highlight work in three distinct regions with a focus on repeatable cycles associated with non-anthropogenic environmental drivers, and finally will explore the effects of human activity on reefs that may be reflected in reef soundscapes.
An investigation on the mechanism(s) behind sonodynamic therapy and the use of sonosentizers
Authors: Walton Stephanie C.
Published: July 2024

Over the last 30 years, sonodynamic therapy (SDT) has been under investigation as a treatment for malignant tumours. SDT utilizes ultrasound in combination with a sonosensitizer to cause cell death. While this treatment is in use, there remains critical questions that limit the translation of this promising therapy into the clinic. Chemical or physical changes occurring due to ultrasound may explain the efficacy observed and depending on the frequency and intensity of sound used, cavitation may be an important component of this. Some findings indicate that collapsing bubbles, or sonoluminescence, may cause the sonosensitizers to split, creating reactive oxygen species (ROS). Other research suggests damage to cell structure due to the ultrasound waves is the key. Understanding the required balance of chemical and physical effect for varied cancer cells is critical to optimization of the treatment. This paper presents a preliminary investigation of the cause of cell death observed in SDT, with focuses on ROS generation, the use of ultrasound to activate chemical compounds, and observable mechanical damage to cells following ultrasound exposure.
Ultrasound Targeted Microbubble Cavitation (UTMC) for the treatment of Myocardial Microvascular Obstruction (MVO)
Authors: Amjad Muhammad Wahab , Mohammed Soheb Anwar , Chen Xucai , Villanueva Flordeliza S. , Pacella John J.
Published: July 2024

Congestive heart failure following acute myocardial infarction is increasing due to microvascular obstruction (MVO), for which there is no effective therapy. We have been developing ultrasound-targeted microbubble cavitation (UTMC) as a potential treatment. Rapacz familial hypercholesterolemic (RFH) pigs were used in this study. MVO was created in the left anterior descending (LAD) microcirculation. UTMC therapy was applied during infusion of Definity®. Left ventricular (LV) segmental wall motion and microvascular perfusion were assessed with ultrasound. Cardiac MRI was obtained to measure infarct size and area of MVO; ultrasound imaging and coronary angiography were performed at 48h. LAD angiographic flow was improved at 48 h post-treatment in comparison to control. UTMC treatment significantly improved echo-based LV systolic performance. UTMC was also found to significantly enhance LAD blood volume at 48h versus control. MRI-derived LV segmental wall motion and ejection fraction also improved post-treatment. Infarct size was reduced as assessed by both Evans Blue/TTC staining and MRI. In conclusion, we demonstrated that UTMC significantly reduced infarct size, enhanced LAD microvascular perfusion and improved LV systolic performance.
Multiple scattering analysis of phononic crystals
Authors: Torrent Daniel , Martí Sabaté Marc , Guenneau Sebastien
Published: July 2024

Multiple scattering theory allows for the computation of states and scattering fields on a diverse variety of wave systems. Through rigorous analysis, this theory provides insights into wave phenomena such as diffraction, reflection, and transmission, contributing to a comprehensive understanding of the intricate dynamics of classical systems. Our study focuses on flexural waves in thin elastic plates, with point-like mass spring resonators serving as scatterers attached the plate’s top surface. Finite clusters of scatterers will be analysed without imposing symmetries or periodicity in the system. Despite the apparent simplicity of this model, it proves capable of unveiling and predicting many behaviours related to the latest topics on metamaterials, including phononic crystals, quasicrystals, topological insulators, rainbow trapping effects or spatio-temporal modulation. In essence, this technique offers a foundation for advancements in materials science, structural engineering and all the domains where metamaterials and phononic crystals find application.
Emotion equalization app: The effectiveness of dynamic music therapy approaches
Authors: Law Man Hei , Horner Andrew B.
Published: July 2024

A recent study explored how static music playlists of relaxing or uplifting music can improve our mood. Unlike static playlists that rely exclusively on relaxing, uplifting, or consoling music, this study explores eight distinct methods to curate playlists. These approaches include transitions from one dimension to another (e.g., Angry-to-Relaxing, Angry-Uplifting, Relaxing-Uplifting, Relaxing- Natural, Sad-Relaxing, Sad-Uplifting, Uplifting-Relaxing, and Uplifting-Natural). To evaluate the effectiveness of these playlists, online experiments were conducted, wherein participants were surveyed before and after music listening to monitor changes in valence and arousal. The results reveal that Sad-Relaxing, Relaxing-Uplifting, Relaxing-Natural, and Uplifting-Natural playlists give positive changes in participants' valence levels, indicating mood improvement. As for the arousal level, the Angry-Relaxing playlist made people feel calmer. Correspondingly, the Relaxing-Uplifting playlist made people feel more energetic. Moreover, this study has identified specific pathways on a two-dimensional plane where both arousal and valence values could be profitably to good effect, including transitioning from Angry to Relaxing to Uplifting especially for arousal, and Sad to Relaxing or Uplifting especially for valence. These findings highlight how dynamic music can give rise to distinct emotional responses and influence our energy levels, and give guidelines on how to use music therapy playlists for mood enhancement.
Influences of electric guitar pickup magnetic force on string vibrations
Authors: Yudasaka Takuto , Scavone Gary , Ishizaka Kenta
Published: July 2024

The design of a magnetic pickup has a significant impact on the tone of an electric guitar. In particular, the magnetic force from the pickup can influence the string vibrations and cause a beating effect, depending on the strength of the magnetic force and the amplitude of the string vibrations. To understand this behavior, we performed experiments and simulations. We measured and modeled the transversal string restoring force at various displacements from the magnetic pickup in directions both parallel and perpendicular to the guitar body. We observed that the magnetic force distribution is asymmetric in the perpendicular direction but symmetric in the parallel direction, which distorts the frequency of vibrations in opposite ways for the two directions and causes a resultant beating. This effect increases with larger string amplitudes or greater magnetic force and also varies over the duration of a plucked tone.
Adaptive zone based active noise control for a moving target
Authors: Ghebreiyesus Wintta , Hasan Sifat , Xi Fengfeng (Jeff)
Published: July 2024

This study focuses on enhancing active noise control (ANC) in room enclosures, specifically targeting zones of quiet (ZoQ) around aircraft passenger seats. By integrating virtual sensing and motion tracking techniques, we aim to dynamically adapt the ZoQ to moving targets. Key to our approach is the strategic placement of actuators and sensors, forming the core of the ANC system. Our methodology includes virtual sensing for ANC analysis, ZoQ optimization for varied applications, and in-depth case studies. We introduce an innovative combination of a speaker gimbal system, a vision system, and custom software for precise motion tracking, significantly improving ZoQ localization. The findings offer insights into maintaining effective ZoQs for multiple input multiple output (MIMO) local ANC configurations, laying the groundwork for adaptive ZoQ control about sound sources and desired cancellation locations. This research marks a significant step towards more effective and adaptable noise cancellation in enclosed spaces.