bluuebunny/crossref_metadata_2025 huggingface dataset:
Low-cost assimilation for sound speed fields in the PCA framework
Authors: Marple Gary , Walker David
Published: November 2022

Forecast ocean sound speed fields are often inaccurate and need to be reconciled with observation data. Conventional data-assimilation methods used for this are generally quite computationally intensive. A compressed representation of the forecast sound speed fields can be obtained using principal component analysis (PCA), where the forecast fields are represented by a linear combination fo PCA modes. We develop a low-cost assimilation approach that updates the PCA compressed representation of the background forecast field, based on observation data.The approach uses Bayes‘ rule to obtain the maximum likelihood estimate for the update in the space spanned by the PCA modes. Significant cost savings come from the dimensionality reduction that is provided by PCA. Results are presented for sound speed fields derived from HYCOM ocean forecast data and expendable bathythermograph data obtained from the Scipps Institution of Oceanography.
The soundscape of two deep-sea hydrothermal vent sites
Authors: Smith Brendan , Barclay David R.
Published: November 2022

Hydrothermal vents are sea floor structures where geothermally heated seawater is discharged. The high-temperature, chemically rich environment is host to uniquely adapted marine life. Vent soundscapes may contain important bioacoustic cues as well as signals enabling passive acoustic monitoring of hydrothermal vent dynamics. Proposals for deep-sea mining of seafloor massive sulfides near hydrothermal vents have elicited concern over potential environmental impacts due to disturbance from industrial activity, including changes to the soundscape. This study assesses the baseline soundscape at two sites, the Main Endeavour Field on the Juan de Fuca Ridge and the Lucky Strike vent field on the Mid-Atlantic Ridge over 12 months and 3 months respectively. To facilitate comparison with future studies at other sites, the most recently proposed standard soundscape analysis methodologies are employed, including terminology in alignment with ISO 18405:2017. In accordance with the latest soundscape standard literature, metrics quantifying the amplitude, impulsiveness, periodicity, and uniformity are reported. Spectral probability densities, percentiles, and long-term spectrograms are computed in hybrid millidecade frequency bands. Finally, a qualitative analysis is included to describe the source types contributing to the hydrothermal vent sound field.
Real-time instantaneous wide-area ocean acoustic monitoring in the shallow Great South Channel and deep ocean south of Rhode Island with Northeastern University coherent hydrophone array
Authors: Seri Sai Geetha , Mohebbi-Kalkhoran Hamed , Radermacher Max , Schinault Matthew E. , Zhu Chenyang , Makris Nicholas C. , Makris Purnima R.
Published: November 2022

A large-aperture 160-element coherent hydrophone array system, developed in-house at Northeastern University, was deployed and tested at sea in shallow water Great South Channel and deep ocean south of Rhode Island during September 2021. The system implements the passive ocean acoustic waveguide remote sensing technology for real-time instantaneous wide area ocean monitoring. The array data sampled at 100 kHz per element were processed in real-time at sea to provide beamformed spectrogram imagery in multiple frequency subbands from 10 Hz to 50 kHz and spanning 360 degree horizontal azimuths about the receiver array. A wide variety of acoustic detections were made in real time, including marine mammal vocalizations and motion-related signals, fish grunts and other fish-generated signals, tonal and broadband signals from distant ships and own tow ship. Real-time detections of marine mammal vocalizations include fin whale 20 Hz pulses, humpback whale songs and social sounds, minke whale buzz sequences, sperm whale echolocation and social clicks, dolphin whistles and echolocation clicks, as well as calls from unidentified baleen and toothed whale species. A database of automatically detected signals with bearing-time information along with extracted time-frequency characteristics was generated in real-time at sea.
Dictionary learning for classification of sound speed profile in the ocean
Authors: Castro-Correa Jhon A. , Badiey Mohsen , Wan Lin
Published: November 2022

Internal waves (IWs) are waves that propagate along density gradients within the water column and alter the isotropic properties of sound speed profiles (SSPs). Changes in the SSPs modify the acoustic channel ducts and affect underwater acoustic propagation, causing most of the energy to be dissipated into the seabed due to the downward refraction of sound waves. Therefore, variations in the SSP must be considered when modeling acoustic propagation in the ocean. It has been proved that Dictionary learning (DL), an unsupervised machine learning method, succeeds in sparsely representing signals by employing a few non-orthogonal basis functions (atoms) learned from data. In this work, we use the ability of learned dictionaries (LDs) for data representation and thus train class-specific dictionaries to capture relevant features from labeled data within a supervised learning setting. We developed an LD-based supervised framework for SSP classification and compared it with state-of-the-art models. The algorithms presented in this work are trained and tested on data collected from the shallow water experiment 2006. Results show that overcomplete DL is a robust method to classify SSPs during IW activity, reporting comparable and higher accuracy than standard supervised classification methods. [Work supported by ONR, Grants No. N00014-21-1-2424 and N00014-21-1-2760.]
Volume scattering of sound signals in gassy bottom and estimation of bubbles concentration in Lake Kinneret
Authors: Uzhansky Ernst , Katsnelson Boris , Lunkov Andrey , Katsman Regina , Ivakin Anatoliy N.
Published: November 2022

In the paper, results of experiments in shallow Lake Kinneret (Israel) and the corresponding data processing are presented. Wideband LFM sound signals (300 Hz–3.50 kHz and 300 Hz–15 kHz) were radiated by the source mounted directly on vertical line array (VLA) of the length 20 m placed at several locations with different water depths (from 20 to 35 m). Received sound field timeseries constitutes a sequence of pulse arrivals comprised of specular reflections from interfaces followed by reverberation codas caused by non-specular scattering from the interface roughness and volume inhomogeneity. Properties of received signals are analyzed assuming that the sediment can be modeled as a thin layer containing bubbles over a homogeneous fluid half-space. Using a set of hydrophones of VLA allowed isolation of the volume scattering component, estimating frequency-angle dependences of scattered field, and hypothesizing some properties of the gassy sediment, such as concentration of bubbles and their effective size. [Work was supported by BSF grant 2018150.].
Low-order acoustic mode arrivals in the Beaufort Duct
Authors: Desrochers Jessica , Van Uffelen Lora , Webster Sarah E. , Muniz Alexander P. , Graupe Cristian E. , Pomales Velázquez Luis O.
Published: November 2022

Significant changes in the stratification of the Beaufort Sea over the last few decades have produced a subsurface duct located between 100- and 300-meters depth, known as the Beaufort Duct. This subsurface duct allows for long-range acoustic transmission with little to no interaction with the sea surface or seafloor. In August and September of 2017, acoustic transmissions from five active moored tomography sources were collected at ranges up to 530 km by two Seagliders along with in-situ environmental measurements. Sound-speed profiles from the Seaglider data were used as input for parabolic equation and normal mode predictions. Both the predictions and recorded acoustic data show a peak acoustic arrival prior to the final cutoff. We refer to this as a “foldover” feature in the acoustic timefront, and it can be connected back to the unique ducting features in the input sound speed profiles. The relationship between the extent of the foldover and the shape of the sound-speed profile in the duct is explored using normal modes. Modal group speed predictions for the low-order modes are used to understand which modes make up the foldover feature present in the acoustic timefront and to interpret the acoustic arrival patterns measured on the Seagliders.
Enhancing underwater Acoustic Identification Tag design using concurrent wireless ultrasonic power transfer and backscatter communication
Authors: Bhardwaj Ananya , Allam Ahmed , Erturk Alper , Sabra Karim G.
Published: November 2022

Improvements in undersea localization and navigation of Autonomous Underwater Vehicles (AUVs) is critical. However using conventional active transponders as navigation aids is limited by powering constraints. Passive backscatter devices such as Acoustic Identification (AID)Tags are an alternate solution to this energy limitation [Satish et al., JASA 149 (2021)], but offer limited information content. To address this limitation, adding a wireless ultrasonic power transfer capability to these passive AID tags can be used to enable backscatterer uplink communication between the AID tag and an interrogating compact high-frequency SONAR system (which can be mounted on an AUV). Our design comprises a piezoelectric transducer impedance matched to a connected electrical load across two frequency ranges: a narrowband energy harvesting range, and a broadband data range. Onboard electronics harvest acoustic energy in the narrowband to power an onboard microcontroller, which can be used to simultaneously modulate the transducer broadband acoustic impedance by switching the electrical load connected to transducer during backscatter uplink communication. Water tank experiment using custom transducers, operating either around 1 MHz or 350 kHz, were conducted to quantify-amongst others-the operational source to tag distance, system power requirements and achievable communication data rates using the proposed concurrent ultrasonic power and data transfer approach.
Detection and quantification of bubble activity in therapeutic ultrasound: Magnetic resonance imaging for cavitation detection and quantification
Authors: Allen Steven P.
Published: November 2022

For some applications of therapeutic ultrasound, magnetic resonance imaging (MRI) may serve as a useful tool for detecting, measuring, and quantifying cavitation activity—especially in cases where direct sampling of acoustic emissions are difficult. Doing so can be challenging because the physical phenomena that drive ultrasonic cavitation (e.g., pressure, surface tension, micro-second time scales) have little overlap with the phenomena that drive MRI (e.g., quantum spin, Faraday induction, milli-second time scales). However, this same principle also protects MRI-based cavitation detection from common confounds that plague traditional direct acoustic detection. The proposed paper will first review known methods for encoding cavitation behavior into MR images. These methods generally employ one of two strategies: (1) Encode transient cavitation activities into otherwise approximately static MR signal sources.; and (2) Leverage the time-average effects of many, many cycles of cavitation activity to alter MR signal sources. This paper will then discuss how these methods may be useful to therapeutic ultrasound applications. Finally, this paper will pose opportunities for future development.
Spatial-coherence-based beamforming for image quality enhancement in high frame-rate ultrasound imaging
Authors: Matrone Giulia , Ramalli Alessandro
Published: November 2022

Several high frame-rate ultrasound imaging techniques have been recently proposed which allow to increase image acquisition rates by transmitting multiple focused beams simultaneously or defocused waves, and reconstructing multiple scan lines in parallel. These methods, which include for example multi-line transmission, plane/diverging wave imaging, and parallel beamforming, have proved to be successful in increasing the frame-rate, but on the other hand they have also showed some limitations in terms of the achievable image quality, partly degrading image contrast and resolution. Different solutions have been proposed to address this problem so far, such as the use of advanced receive beamforming algorithms able to improve the beam shape and the quality of the obtained image. Among these, beamformers based on backscattered signals spatial coherence, as e.g. Filtered Delay Multiply and Sum beamforming, Coherence-Factor-based methods, and Short Lag Spatial Coherence Imaging, have gained increasing attention for their ability to enhance image contrast and suppress clutter. In this presentation, an overview of some recent results obtained by jointly exploiting high frame-rate ultrasound imaging and coherence-based beamforming methods will be presented, showing through experimental tests the performance improvement achievable with these techniques.
Beamforming of 3D ultrasound signals with full or sparse probes: New perspectives for volumetric imaging
Authors: Varray François
Published: November 2022

The advances of 2D arrays and 3D ultrasound systems open new perspectives for volumetric US imaging. Coupled with the ultrafast acquisitions, the quantity of acquired data to process expand and the beamforming could become a bottleneck in the processing, especially if volumes are reconstructed in real time. In this work, we propose to study the impact of the beamformer on 3D volumetric images, such as coherence factor, sign coherence factor, phase coherence factor or pDAS. Indeed, such beamformers, adaptive or not, can be easily transfer to 3D but their studies are limited in 3D volumetric situation. Moreover, the introduction of fully populated array required the used of advance and expensive systems. To this end, the utilisation of sparse probes is a promising solution to reduce the number of signals to manage and the complexity of the used hardware. However, the impact on the reconstructed volumes have to be evaluated and the presented beamforming strategies will be presented in both fully and sparse probes.
Measurement and modeling of an electromechanical spring reverb device
Authors: Spratt Kyle S. , Abel Jonathan S.
Published: November 2022

A spring reverb is an electromechanical device used to artificially reverberate an audio signal, i.e. to impart a sense of spaciousness to the audio signal, as if the sound were being emitted into a reverberant acoustic space. The device consists of a number of helical springs set into motion by electrically driven magnetized beads, with the elastic wave motion along the springs being analogous to acoustic waves propagating along the various dimensions of a room. While originally invented by the Hammond organ company to add a sense of spaciousness to the sound of their electric organs, spring reverbs have been used in a number of electronic instruments and audio devices over the years, with probably the most iconic and enduring use being in classic electric guitar amplifiers. In this talk, a general overview of the history and technical aspects of spring reverb devices will be given, with particular emphasis placed on the highly dispersive nature of elastic wave propagation along helical springs, which it will be argued is primarily responsible for the distinctive sound of the device. Finally, a simplified computation model will be presented that captures the salient features of a spring reverb device.
Physical modelling for analog tape emulation
Authors: Chowdhury Jatin
Published: November 2022

Reel-to-reel magnetic tape recording has a unique and specific sound which is highly sought after by music recording engineers. This talk will discuss the use of physical modelling signal processing to create algorithms which can emulate the sound of any reel-to-reel tape recorder, including ones which may not actually exist in the real world. These algorithms are designed to be used in modern music production software, meaning that they must be able to process audio in real-time with minimal latency, and offer interactive controls to the end user.
Atom Tones: investigating waveforms and spectra of atomic elements in an audible periodic chart using techniques found in music production
Authors: Linz Jill A. , Howat Christian
Published: November 2022

Atom Music was introduced in 2019 as a way to create unique audible tones for each atomic element that are direct translations of that element’s spectral lines. Each atomic element produces a unique spectral line pattern that can be recognized as the fingerprint of that element. Sonification is the process of translating non-audible data into audible signals as a way to gain an understanding of the original data. In this paper, sonification is applied to atomic spectra, using technology primarily from music production. These were applied to atomic spectra using additive synthesis methods and analyzed using digital audio workstations. Interest in the audible tones has primarily been in element identification through each tone, as well as those interested in musical interpretation. We investigate what insights can be made by observing the digital waveforms and spectra of each element tone. We consider whether there are patterns within the different element waveforms; if there is any correlation between the elements producing similar beat patterns; and if there are any harmonic relations between electron states that are represented by the spectra itself. Results indicate that this method could be a useful tool in investigating atomic structure.
Simplified prediction of near-field jet coherence using the cross-power spectral density acoustic analogy
Authors: Miller Steven A.
Published: November 2022

The cross-power spectral density (CPSD) acoustic analogy is a generalization of Lighthill’s analogy that directly predicts near-field statistics at multiple spatial points. The methodology was previously applied and validated to predict noise from isotropic turbulence and off-design supersonic jet flows. We present a simplification of the CPSD model for near-field predictions of acoustic coherence from jet fine-scale mixing noise. Validation predictions are presented with a NASA Glenn Research Center experimental jet database. The simplified mathematical model is presented along with the physical significance of each term. The application of the model can be applied to predict loading and coherence on the fuselage of aircraft, rockets, and associated structures. This approach can help designers minimize sonic fatigue or failure in flight-vehicles and support structures.
The full spectrum of broadband shock cell noise
Authors: Tam Christopher
Published: November 2022

Broadband shock cell noise has been studied by numerous investigators since the work of Harper-Bourne and Fisher (1973). This noise component radiates in the upstream direction together with another noise component, the fine scale mixing noise. In measured noise spectra, broadband shock cell noise shows up as a small peak protruded up from a broad background noise. The spectral shape of the peak has been studied by Tam (1990) and Kuo et al. (2015). Good agreements are found between predictions and measurements. This situation begs the question of the shape of the full noise spectrum. The answer lies in devising a way to separate the two noise components. Here, this is done at the raw data level. We know broadband shock cell noise is generated by the interaction between large turbulent structures and shock cells whereas mixing noise is generated by fine scale turbulence. One, therefore, expects a scale separation between the two noise components. Broadband shock cell noise sound pulses are expected to have a longer duration or larger pulses while turbulent mixing noise much shorter pulses. This idea has now been implemented on a set of F-18E noise data at 28 degrees. Results and relevant details will be reported.
Deflector shape impact on aero-acoustic noise generation and propagation
Authors: Escartí-Guillem Mara S. , Hoyas Sergio , Garcia-Raffi Luis M.
Published: November 2022

The vibroacoustic loading generated during the launch of space vehicles can cause the failure of electronic and mechanical components. Therefore, the prediction and mitigation of these vibroacoustic levels are crucial to improve the reliability of launchers and payload comfort. Because a properly designed flame deflector has the power to significantly reduce the acoustic pressure level, the aeroacoustics characteristics of diverse types of flame deflectors must be understood. Three different deflector geometries have been analysed: a wedge-type deflector, which is currently used on the VEGA rocket launch pad, a 30-degree inclined deflector, since new studies highlight its noise reduction capacity, and a flat deflector, since the impact on a flat plate is the simplest case of reflection. The sound generation and propagation in the launch platform full domain for each case were studied using dedicated computational fluid dynamics in BSC MareNostrum. To assess noise generation, the main shock waves were identified, and the evolution of the generated sound pressure was assessed. Moreover, the sound pressure levels at the fairing surface have been studied. Further research is focused right now on the use of an efficient solver running on graphics processing units that is capable of computing large-scale turbulence.
A nonlinear distortion length of the statistics of high-amplitude propagating noise
Authors: Muhlestein Michael B. , Gee Kent L.
Published: November 2022

The nonlinear evolution of high-amplitude broadband noise is important to the psychoacoustic perception of high-speed jet noise. One method to characterize the nonlinear evolution of such noise is to consider a characteristic nonlinear distortion length for the signal. A common length scale for this analysis is the shock formation distance of an initially sinusoidal signal. However, application of the shock formation distance for an initially sinusoidal signal to broadband noise, even with the amplitude and source frequency replaced with characteristic values, may lead to inaccurate interpretations. Here we derive an alternative length scale from the evolution of the skewness of the pressure time-derivative of Gaussian noise that may be more appropriate when analyzing the nonlinear evolution of broadband noise signals. This length scale is then used to demonstrate how numerically propagated noise signals are fundamentally different than numerically propagated initially sinusoidal signals.
Reanalysis of subjective crackle ratings using a logistic curve fit
Authors: Swift S. Hales , Gee Kent L.
Published: November 2022

Prior work has shown a robust relationship between crackle from high-performance jets and the skewness of the distribution of the first time derivative of the pressure waveform; however, prior efforts have characterized this relationship in terms of a linear relationship between the log of the derivative skewness and the category scaling responses. While the relationship is linear over important portions of its range, the use of a logistic curve fit more fully captures the characteristics of the relationship between log first time derivative skewness and category scaling relationship including implied non-negativity, and saturation. Accordingly, a logistic curve is fit to these data, and the residual magnitudes are compared between the two fitting approaches.
Application of a crackle-based adjustment to military aircraft noise levels
Authors: Harker Blaine M. , Downing J. M. , James Michael M. , Gee Kent L.
Published: November 2022

Crackle is a sound quality that can be identified in the jet noise of tactical aircraft and may contribute to perceived community noise levels in the vicinity of military airports. Crackle has been linked to the skewness of the waveform pressure derivative, or derivative skewness. Recently, listener trials quantified the perceptual relationships between derivative skewness, loudness, and annoyance. We present a method to calculate a crackle-based adjustment to aircraft noise levels derived from annoyance. This crackle adjustment is applied to a large sample set of community noise measurements in the vicinity of departing military aircraft. Finally, we develop an empirical model to apply crackle-based adjustments to community noise models of tactical aircraft departures. The empirical model allows airport planners to examine how aircraft flight paths, altitudes, and engine conditions affect the crackle adjustment, which is significant in the airport's immediate vicinity and along the aircraft departure path. [Work funded by an AFRL SBIR.]
Optically excited nanoparticle enhanced high intensity focused ultrasound therapy of in vivo cancer models
Authors: Ingram Nicola , Egnuni Teklu , Freear Steven , Coletta P. Louise , McLaughlan James
Published: November 2022

The use of plasmonic gold nanoparticles (AuNP) that have been actively targeted to a specific tumour region is a highly active area of research for both drug delivery and hypothermia applications. One application is providing in situ cavitation nuclei for enhancing high intensity focused ultrasound (HIFU) ablation. When the nanoparticles are simultaneously exposed to HIFU and pulsed laser illumination, microscopic vapour bubbles form providing a controllable way to nucleate cavitation. Using an EGFR-expressing head and neck xenograft model, the biodistribution of targeted and untargeted AuNPs were examined using multispectral, whole body photoacoustic imaging, and inductively coupled plasma mass spectrometry (ICP-MS) analysis following systemic or intratumoral injections. Systemic delivery showed negligible concentration of AuNRs in the tumour; however, intratumoral injection increased its concentration, but remained in the tumour at high concentration for the first 48hrs. Evaluation of ablation performance was undertaken using the same tumour model. An intratumoural injection of untargeted particles, with single 10 s continuous wave HIFU exposures for peak positive/negative pressures of 2.4/2.0 MPa, with simultaneous illumination of 1064 nm pulsed laser light with a surface energy density of 70 mJ/cm2. Post treatment tumour volume was monitored using high frequency ultrasound imaging and calliper measurements, to evaluate exposure efficacy.
Detection of HIFU lesions by optical coherence tomography
Authors: Raymond Jason L. , Marques Manuel , Everbach E. Carr , Hughes Michael , Roy Ronald A. , Podoleanu Adrian
Published: November 2022

The use of high-intensity focused ultrasound (HIFU) to induce irreversible changes in tissue due to heating is well established. We have shown that changes in tissue optical properties (scattering and absorption coefficients) could be used as a proxy to improve sensing and imaging of HIFU lesion formation, as an alternative to conventional methods such as thermometry. Optical coherence tomography (OCT) is a non-invasive optical imaging method which relies on low-coherence interferometry to determine the depth of individual scattering centres within the tissue. Previous studies have demonstrated that OCT signals are sensitive to morphological changes in heated tissue, likely due to denaturation of proteins concomitant with formation of crosslinked structures. The goal of this study was to assess the use of OCT for sensing and imaging HIFU lesions. We demonstrate the feasibility of imaging near-surface lesions in ex vivo chicken breast tissue exposed to HIFU. This technique has potential for detecting changes in optical properties corresponding to the progression of surface lesion formation which are antecedents of skin burn during HIFU exposures, thereby increasing safety and reducing treatment times.
A ray tracing approach to focusing ultrasonic beams in isotropic and anisotropic solids
Authors: Katch Lauren , Arguelles Andrea P.
Published: November 2022

Focal depths in solid materials are generally calculated using analytical expressions that rely on the paraxial approximation (i.e., small angles related to shallow focusing). However, with increasing use of highly focused probes for acoustic microscopy and backscattering studies, these assumptions are often challenged. Additional challenges are posed by the presence of material anisotropy within the solid. In this presentation, we present a ray tracing based approach to characterize ultrasonic beam focusing when using highly focused ultrasonic transducers. The results are compared to traditional methods to calculate focal regions to evaluate the range of applicability for isotropic and anisotropic materials. For isotropic solids, a non-paraxial focusing equation is derived and compared to the conventional focusing equation for both normal incidence and oblique incidence immersion setups. Both focusing equations are compared through ray diagrams where the proximity to the true geometric focus is explored. The proposed focusing equation results in a closer approximation to the geometric focus, a smaller beam cross-section, and a greater time convergence compared to the conventional focusing equation. Lastly, the results are expanded to anisotropic media where potential for multiple foci and complex beam behavior arise.
Nonlinear acoustical transmission through a weak shock wave
Authors: Coulouvrat Francois
Published: November 2022

Recent experiments (Ducousso et al., Phys. Rev. Appl., L051002, 2021) demonstrated the possibility to image weak shock propagation in solids by an ultrasonic probe wave. Wave interaction with a steady, ideal step shock in air has been previously described (Burgers, Selected Papers, Springer, 478–486, 1995—McKenzie and Westphal, Phys. Fluids, 11, 2350, 1968), without consideration for the particular case of a weak shock nor for the influence of the medium. The present paper considers a weak shock interacting in any inviscid fluid with an incident probe wave. No reflected wave arises. The transmitted wave, vortex and entropy modes behind the shock, and the shock front disturbance, are determined by the linearisation of the Rankine-Hugoniot relations. For a weak shock, entropy mode and energy jump relation can be omitted. The shock motion induces a Doppler effect dependant on the medium, air and water giving opposite trends. The transmitted wave amplitude is either increased or reduced through energy exchanges with the shock. For an incidence beyond the critical angle, instead of a total reflexion, an inversion of the direction of the transmitted wave occurs, propagating in the same direction as the shock. This phenomenon seems specific to weak shocks.
Using frequency selectivity to examine category-informative dimension-selective attention
Authors: Luthra Sahil , Obasih Chisom O. , Tierney Adam , Dick Frederic , Holt Lori
Published: November 2022

In everyday situations, listeners may selectively attend to acoustic dimensions (e.g., frequency) within complex sounds and ignore other simultaneous dimensions. Speech sound categories are defined over multiple dimensions that vary in informativeness; thus, speech perception may demand selective attention to diagnostic dimensions. Here, we examine how selective attention affects cortical representations of informative acoustic dimensions during category learning. Participants completed a five-day training regimen wherein they learned four novel non-speech categories to criterion (Obasih et al., in prep). Crucially, stimuli were designed such that for two categories, categorization required reliance on – and perhaps selective attention to – acoustic patterns within high-frequency bands; the other two categories were differentiated by acoustic patterns in low-frequency bands. After training, listeners completed an fMRI session using the same non-speech categorization task. Best frequency for each auditory cortex voxel was obtained using tonotopic mapping. We hypothesized that when categorization depended on distinctions in certain frequency ranges (e.g., high frequencies), listeners would selectively attend to those frequencies, resulting in greater recruitment of voxels preferring those frequencies and possibly attenuation of signal in voxels preferring other frequencies. We present preliminary data from our study, with the goal of clarifying the cortical mechanisms supporting dimension-based auditory selective attention.
Explaining the deterioration of the relative timing accuracy for across-channel by a simple mathematical model
Authors: Okazaki Satoshi
Published: November 2022

The perceptual simultaneity range, within which two asynchronous pure tones are perceived to start simultaneously, and the gap detection threshold are known to be wide when the frequency separation of the tones is large. It is generally said that the accuracy of the relative timing for different frequency channels deteriorates. However, there is no clear explanation of why such deteriorations are necessary. This study aimed to show that a simple mathematical model leads to the deterioration of relative timing accuracy for two tones with different frequencies. As a result of the calculations, the model simulated the deterioration of the perceptual simultaneity range not only with the increase of the frequency separation but also with the decrease of the frequency region of two tones. The model also simulated the behavior of the gap detection threshold for two different frequencies (across-channel) with its asymmetric deterioration. Further, the model simulated the behavior of the gap detection threshold for two identical frequencies (within-channel). These results suggest that one simple mathematical model may explain the mechanisms underlying perceptual simultaneity, within-channel gap detection, and between-channel gap detection for two tones.
Mismatch negativity linked with sound lateralization in elderly individuals
Authors: Morita Kazumoto , Shiroki Moeko , Iwaki Sunao , Toi Takeshi
Published: November 2022

Elderly individuals tend to experience a decline in auditory functions. One of these is poor lateralization ability. This study aimed to investigate the relationship between sound lateralization and mismatch negativity (MMN) in elderly individuals using a lateralization test and event-related potential (ERP) measuring test. In the lateralization test, participants were presented with sound stimuli with an interaural time difference (ITD) in the right or left ear and were required to indicate the sound direction. The ERP measuring test estimated unconscious brain activity during participants’ exposure to sound stimuli using an ITD in the right or left ear. Two ITDs (i.e., 0.4 ms and 0.8 ms) of a 1-kHz pure tone were measured in elderly and young participants. For sounds with phase reversal between the onset and ongoing parts, young individuals performed lateralization based on the onset part. In contrast, at an ITD of 0.8 ms, elderly participants unable to perceive the onset part tended to demonstrate less negative MMN. In conditions where the preceding ear in onset and ongoing parts was reversed, elderly participants exhibited ambiguous lateralization, and their cortical evoked potentials did not significantly differ from activity associated with standard stimuli without an ITD.
The influence of binaural cues on the promotion or inhibition of auditory stream segregation
Authors: Higgins Nathan C. , Ozmeral Erol J.
Published: November 2022

Though much is known about detection thresholds for binaural cues (interaural time [ITD] and level differences [ILD], and interaural correlation [IAC]), less is known about how these cues influence the separation of auditory sources. The ABA auditory stream segregation paradigm (Bregman, 1990) in a bistable configuration, elicits roughly equivalent proportions of integrated and segregated percepts, where listeners spontaneously switch back and forth between the two. To determine the influence of binaural cues we periodically (25 s) manipulated the binaural cue carried by the A components of the ABA triplet (made of narrowband noise, 6-semitone separation) while maintaining the B component at a stable binaural cue. Participants continuously indicated their perception via button box. Analyzed as a function of binaural cue, lateral cues were more likely to be reported as segregated than midline cues. Binaural cue boundaries (perceptual transition point) were defined using logarithmic regression and were significantly correlated for ILD and ITD (r2 = 0.65, p < 0.05). IAC modulation resulted in significantly more switches when both the A and B components were centered (IAC = 1) than when the IAC of the A component was more diffuse (IAC < 0.9). These results provide evidence of how listeners functionally use binaural cues to segregate auditory streams.
Cochlear mechanics from correlation between multiple travelling waves from oval window
Authors: Biswas Amitava
Published: November 2022

Many models of cochlear mechanics have been commonly perceived to be plausible. These models primarily assume a resonance in the neuro-mechanical system of the cochlea. An inherent challenge thatremains to be addressed is the rapid changes in speech sounds during rapid utterances of syllables that could not be demonstrated to be precisely recognized by such a traditional resonance system that needs much ore response delay to work properly. Whereas, we know the human auditory system can easily identify slight changes in syllables in terms of rate of production, slight changes in intonation, prosody, and so forth. For example, an average listener can quickly identify whether the singer of a recorded song is a particular celebrity and whether another recording is an identical copy or slightly different version, even if the singer is the same person. Therefore, there is a definite need to explore other mechanism in the cochlear mechanics other than simple resonance that can not respond so rapidly and so precisely simultaneously. As we know, rapid response of traditional resonance system requires sacrificing high precision. And high precision of a traditional resonance system requires sacrificing high speed of response. This trade off behavior is analogous to the well known Heissenberg Uncertainty Principle. Therefore, some alternative mechanism must be present that has not been discovered yet. We will discuss a few plausible paradigms of radically distinct cochlear mechanics from correlation between multiple travelling waves.
Relation between temporal fine structure processing and global processing speed
Authors: Sugai Kelli , Whittle Nicole , Herrera Ortiz Christian , Leek Marjorie R. , Lee Grace , Venezia Jonathan H.
Published: November 2022

Strelcyk et al. (2019) recently found that interaural phase discrimination in older hearing-impaired listeners was correlated with both visuospatial processing speed and interaural level discrimination. This suggests that temporal fine structure (TFS) processing relies on global processing speed and/or spatial cognition, though it is possible that, generally, complex auditory discrimination engages multiple cognitive domains. Here, 50 Veterans (mean age = 48.1, range = 30–60) with normal or near-normal hearing completed batteries of temporal processing and cognitive tests. Composite cognitive test scores reflecting processing speed/executive function (PS-EX) and working memory (WM) were obtained. Temporal processing tasks included measures of envelope (ENV; gap duration discrimination, forward masking) and TFS (frequency modulation detection, interaural phase modulation detection) processing. Bayesian hierarchical regression was used to fit psychometric functions simultaneously to all ENV and TFS tasks in all subjects. Fixed effects of PS-EX and WM on thresholds and slopes were estimated for the psychometric functions in each temporal task. In general, (i) PS-EX and WM influenced both TFS and ENV thresholds, but not slopes; and (ii) TFS thresholds were best explained by PS-EX scores while ENV thresholds were best explained by WM scores. These findings suggest a specific relation between global processing speed and TFS.
Modeling of airborne ultrasound reflection from water surface waves
Authors: Zhang Likun , Zou Zheguang
Published: November 2022

Airborne ultrasound reflection from water surface waves is modelled to advance uses of acoustic signals to measure water surface waves and apply the measurements to explore interactions of water waves with rigid structures in a laboratory setting. When the ultrasound is incident on a moving periodic water surface wave, the reflected signal can be treated as diffraction from a moving corrugated reflection grating. Under the condition that the amplitude of the water surface waves is much less than the incident acoustic wavelength, diffraction theory leads to analytical formulas for the spectra of the acoustic signal relating to the water wave amplitudes and frequencies. Complementary modeling based on ray theory and wave superposition illustrates the diffraction and validates formulas of water wave reflection from a surface-piercing barrier structure, where two counter-propagating water waves are involved.
Extending the vibration-based sound power method to determine the sound power radiated from acoustic sources
Authors: Bacon Ian C. , Ebeling John C. , Sommerfeldt Scott D. , Blotter Jonathan D.
Published: November 2022

A vibration-based sound power (VBSP) method has been developed as an alternative method for determining the acoustic energy radiated from structures. Many acoustic sources, such as a blender or motor, have sound power contributions that originate from within the structure and therefore cannot be scanned properly using a vibrometer. For these types of sources, a rectangular enclosure with five rigid sides and a single mylar side was fabricated to enclose the acoustic source, so that the VBSP method could be utilized to obtain the radiated sound power. A calibration curve was developed to account for the enclosure effects on these sources, and this curve is used to adjust the measured results to give the true free-field radiated sound power. Experimental results will be shown comparing the sound power obtained from the adapted VBSP method with the sound power of the source obtained in a reverberation chamber using the ISO 3741 standard. Furthermore, computational results will be shown comparing the sound power obtained through the boundary element method (BEM) with the sound power obtained by using the velocities calculated from that model processed with our VBSP method. Funding for this work was provided by the National Science Foundation (NSF).
Numerical investigation on the effects of wake-induced vibration fluid flow over airfoil geometries
Authors: Bloomfield Eli , Salman Muhammad
Published: November 2022

Currently, many companies are looking to innovate and decrease economic and environmental impacts in the aerospace, energy, and marine sectors. As companies continue to innovate, airfoil designs used in the aerospace, wind turbine, commercial, and military marine industries, the lighter materials used are more susceptible to fatiguing failures due to vibrations. When these geometries encounter unsteady flow, the airfoil creates a vibration response. If the vibration response is near the natural frequency of the airfoil geometry, catastrophic failure can occur. This paper analyzes the correlation between geometry and frequency response for NACA symmetric airfoils in unsteady flow due to von Karman vortex shedding. The correlation between the shedding frequency of the cylinder and the frequency response of the airfoil is also considered. The paper also aims to determine if there is a correlation between geometry and frequency response amplitude across the frequency spectrum and at the natural frequency of each airfoil. These results were compared to the airfoil natural frequency, determined through Finite Element Analysis (FEA).
Initial studies into camera-based modal force reconstruction
Authors: Collier Sean , Dare Tyler P.
Published: November 2022

Much work has been done toward the reconstruction of an unknown force using measured response. Modal Force Reconstruction (MFR) attempts a solution by using measured modes and vibrations at some number of degrees of freedom. While developed by way of traditional sensors (e.g., accelerometers), the full-field nature of cameras may be exploited for such tasks. In particular, the spatial density of an image can re-establish the traditionally underdetermined problem into one that is overdetermined. Not only does this make the reconstruction well-posed, but the modal matrix being that which needs inversion establishes a niche solution in certain force reconstruction scenarios. This talk will explore the proposed theory behind camera-based MFR and present proofs of concept using analytical models. Limitations and points of error will also be discussed, helping to further establish credibility and understanding. Initial results suggest camera-based MFR to be a viable reconstruction technique with high spatial and temporal accuracy.
Minimization of radiated noise
Authors: Chargin Mladen
Published: November 2022

Radiatednoise from various components is of increasing concern for today's automotive manufacturers. Traditionally, this analysis was usually performed with Boundary Element Method (BEM) software. Analysis results, although interesting in general, do not provide the design engineer with information on how to improve the design. Unfortunately, there is no sensitivity or optimization capability within any known BEM code, especially when coupled with a FEM code, which provides the vibration of the structure. This paper addresses the problem by describing the software developed by CDH, which combines the structural FEM analysis and optimization capability (MSC/Nastran, SOL200)with CDHBEM analysis code such that one can perform analysis andoptimization very quickly and efficiently. This approach is applied to an automotive air cleaner with internal acoustic domain, which is excited by pulsation of intake valves, which then vibrates and radiates noise. The radiated noise is then minimized at five predefined microphone positions in the far field. The maximum pressure was reduced by approximately 16 dB.
Introduction to Ansys NVH solutions focusing on the Vibro Acoustics
Authors: Shah Hardik
Published: November 2022

Product validation focusing on NVH heavily relies on physical testing which put NVH focused validation on right hand side of the Product Validation Process. Due to this, lot many times design changes are not possible or expensive or time consuming which reduces overall product quality. Industries like Automotives and ground transportation, Aero and Defense, High Tech, Industrial products making huge investments on NVH validation to win over customer perception battle. Ansys geared up in providing industry leading NVH Solution with Mechanical, LS-Dyna, Motion, Sound along with other products like Maxwell, Fluent, Optislang. NVH workflows driven by highly correlated simulation models, Integration of our key industry leading technologies and Guided, Automated, DOE friendly, Cloud native NVH Solutions are our TOP 3 goals. To introduce Ansys NVH Solutions focusing on the Vibro-Acoustics to Acoustical Society of America communities, we will cover key capabilities from different products briefly and demonstrate NVH Workflows in detail. Electric Motor NVH Simulation—Excitation generated due to Electro Magnetic forces Powertrain/Driveline/Gearbox NVH Simulation—Excitation generated due to multi body dynamics simulationFan NVH Simulation—Excitation generated due to structural vibration of fan driven by flow simulation.