bluuebunny/crossref_metadata_2025 huggingface dataset:
Knockout of RSN1, TVP18 or CSC1‐2 causes perturbation of Golgi cisternae in Pichia pastoris
Authors: Aw Rochelle , De Wachter Charlot , Laukens Bram , De Rycke Riet , De Bruyne Michiel , Bell David , Callewaert Nico , Polizzi Karen M.
Published: December 2020

The structural organization of the Golgi stacks in mammalian cells is intrinsically linked to function, including glycosylation, but the role of morphology is less clear in lower eukaryotes. Here we investigated the link between the structural organization of the Golgi and secretory pathway function using Pichia pastoris as a model system. To unstack the Golgi cisternae, we disrupted 18 genes encoding proteins in the secretory pathway without loss of viability. Using biosensors, confocal microscopy and transmission electron microscopy we identified three strains with irreversible perturbations in the stacking of the Golgi cisternae, all of which had disruption in genes that encode proteins with annotated function as or homology to calcium/calcium permeable ion channels. Despite this, no variation in the secretory pathway for ER size, whole cell glycomics or recombinant protein glycans was observed. Our investigations showed the robust nature of the secretory pathway in P. pastoris and suggest that Ca2+ concentration, homeostasis or signalling may play a significant role for Golgi stacking in this organism and should be investigated in other organisms.
Multi-Element Stochastic Galerkin Method Based on Edge Detection for Uncertainty Quantification of Discontinuous Responses
Authors: Kawai Shigetaka , Oyama Akira
Published: December 2020

We propose a new multi-element generalized polynomial chaos (MEgPC) method to minimize the computational costs required for the existing MEgPC to circumvent the Gibbs phenomenon in the presence of discontinuities in a random space. The proposed method uses edge detection to capture the discontinuous behavior of a solution with minimal decomposition. In contrast, the existing MEgPC iterates splitting the random space into two equal parts until achieving a sufficient resolution level. We take advantage of the fact that the stochastic Galerkin (SG) methods facilitate adaptive refinement of the decomposition at every time-step during a computation for the proposed method. The numerical experiments for two-test problems demonstrate the performance of the proposed method. The results show that the proposed method is consistently more accurate than conventional methods for sufficiently high polynomial orders with minimal additional computational costs to capture discontinuities.
On the Effect of the Electrical Load on Vibration Energy Harvesting Under Stochastic Resonance
Authors: Alevras Panagiotis
Published: December 2020

Vibration energy harvesting (VEH) is a promising alternative for powering wireless electronics in many practical applications. Ambient vibration energy in the surrounding space of a target application often involves an inescapable randomness in the exciting vibrations, which may lead to deterioration of the expected power gains due to insufficient tuning and limited optimal designs. Stochastic resonance (SR) is a concept that has recently been considered for exploiting this randomness toward improving power generation from vibrating systems, based on the coexistence of near-harmonic vibrations with broadband noise excitations in a variety of practical mechanical systems. This paper is concerned with the optimal conditions for SR in vibration energy harvesters, exploring the frequently neglected effect of realistic architectures of the electrical circuit on the system dynamics and the achievable power output. A parametric study is conducted using a numerical path integration (PI) method to compute the response probability density functions (PDFs) of vibration energy harvesters, focusing on the effect of standard electrical components; namely, a load resistor, a rectifier, and a capacitor. It is found that the conditions for SR exhibit a nonlinear dependence on the weak harmonic excitation amplitude. Moreover, the modified nonlinear dissipation properties introduced by the rectifier and the capacitor lead to a tradeoff between the power output and the nonconducting dynamics that is essential in order to determine optimal harvesting designs.
INCEFA-PLUS Project: Lessons Learned From the Project Data and Impact on Existing Fatigue Assessment Procedures
Authors: Cuvilliez Sam , McLennan Alec , Mottershead Kevin , Mann Jonathan , Bruchhausen Matthias
Published: December 2020

The INCEFA+ project (INcreasing Safety in nuclear power plants by Covering gaps in Environmental Fatigue Assessment) is a five year project supported by the European Commission HORIZON2020 programme, which will conclude in June 2020. This project aims to generate and analyse Environmental Assisted Fatigue (EAF) experimental data (approximately 230 fatigue data points generated on austenitic stainless steel), and focuses on the effect of several key parameters such as mean strain, hold times and surface finish, and how they interact with environmental effects (air or PWR environment).

This work focuses on the analysis of the data obtained during the INCEFA+ project. More specifically, this paper discusses how the outcome of this analysis can be used to evaluate existing fatigue assessment procedures that incorporate environmental effects in a similar way to NUREG/CR-6909. A key difference between these approaches and the NUREG/CR-6909 is the reduction of conservatisms resulting from the joint implementation of the adjustment sub-factor related to surface finish effect (as quantified in the design air curve derivation) and a Fen penalization factor for fatigue assessment of a location subjected to a PWR primary environment. The analysis presented in this paper indicates that the adjustment (sub-)factor on life associated with the effect of surface finish in air (as described in the derivation of the design air curve in NUREG/CR-6909) leads to substantial conservatisms when it is used to predict fatigue lifetimes in PWR environments for rough specimens. The corresponding margins can be explicitly quantified against the design air curve used for EAF assessment, but may also depend on the environmental correction Fen factor expression that is used to take environmental effects into account.
Effect of Neutron Irradiation on the Mechanical Properties of an A508 Cl.2 Forging Irradiated in a BAMI Capsule
Authors: Uytdenhouwen Inge , Chaouadi Rachid
Published: December 2020

The typical operating temperatures of a nuclear reactor pressure vessel in a PWR is typically between ∼290°C and 300°C. However, many BWRs and some PWRs operate at slightly lower temperatures down to 275°C. Most of the literature and neutron irradiation damage is therefore focused on those irradiation temperatures. It is well-known that the lower the irradiation temperature, the more neutron irradiation damage occurs, because no appreciable annealing occurs at approximately 230°C.

The NOMAD-0 irradiation campaign at the BR2 was a preliminary irradiation specifically designed to determine the appropriate irradiation conditions that result in specific irradiation damage levels of an A508 Cl.2 grade at lower temperatures than the usual PWR operating temperature window. The BAMI capsules with controlled He gas gap were used for this irradiation. To avoid temperature gradients from the outside to the center of the cylindrical blocks, the latter were limited in size. Only tensile and fracture toughness data could therefore be obtained with mini-tensile and mini-CT specimens.

The results show that no influence of the temperature gradient could be found on the tensile and fracture toughness properties. The specimen size and geometry on the fracture toughness results was analyzed and discussed. The effect of irradiation temperature on the tensile properties and the transition temperature as determined by the master curve approach on the mini-CT samples is discussed.
A Feasibility Study on Crack Repair in Austenitic Stainless Steel Dry Storage Canisters Using Isothermal Friction Stir Welding
Authors: Bhattacharyya Madhumanti , Charit Indrajit , Raja Krishnan , Darsell Jens , Jana Saumyadeep
Published: December 2020

In recent time, solid state crack repair techniques in spent nuclear fuel dry storage canisters (SNF-DSC) have garnered significant interest. Plates of austenitic stainless steels are usually arc welded to fabricate the cylindrical canisters which are prone to chloride-induced stress corrosion cracking. Friction stir welding (FSW) is considered to be a potential candidate for damage repair. In this work, electrical discharge machining was used to simulate cracks in 304L stainless steel plates of 12.7 mm thickness. Subsequently, isothermal FSW was carried out at two different temperatures (725 and 825°C) in order to repair the simulated crack. Microstructure-mechanical property correlations in FSWed plates were studied in detail. Significant grain refinement observed in the stir zone (SZ) was attributed to dynamic recrystallization occurring during FSW. A comparison of Vickers microhardness showed higher hardness and homogeneity in the 725°C SZ than its 825°C counterpart. The fraction of Σ3 boundary is found to be low in the SZ as compared to base metal (BM). Yield strength of the joints was found to be approximately 100 MPa higher than that of the BM accompanied by a drop in ductility by a factor of 2. Residual stress profile across 825°C weld was measured using x-ray diffraction.
The ASA/ANSI S12.60 criteria for evaluating speech privacy in healthcare and the way forward
Authors: Good Kenneth W.
Published: December 2020

Speech privacy in healthcare spaces is more than just a good business practice. Although speech privacy is required within the HIPAA privacy rule, it is more than just a legal requirement. Speech privacy in healthcare spaces can be a life safety issue. Without confidence of speech privacy, patients maybe more likely withhold personal and embarrassing information necessary for accurate diagnosis and treatment. This paper will review the current state of the ASA/ANSI S12.60 criteria for evaluating speech privacy in healthcare and discuss work moving forward.
The effects of dispersion and noise on time-of-flight estimates of the shear wave speed in viscoelastic media
Authors: Wiseman Luke M. , Urban Matthew W. , McGough Robert J.
Published: December 2020

Shear wave elasticity imaging applies an acoustic radiation force to generate shear waves, where the shear wave speed is often estimated with time-of-flight calculations. To characterize the errors in time-of-flight estimates of the shear wave speed, three-dimensional simulated shear wave particle velocities and shear wave particle displacements are computed with time-domain Green's functions for a Kelvin-Voigt model. Estimated shear wave speeds are obtained from cross correlations and time-to-peak calculations, and the results demonstrate the effects of time-domain dispersion and noise on estimates of the shear wave speed. Time-domain dispersion of the propagating shear wave produces large errors in estimates performed with shear wave particle velocities and/or cross-correlations close to the push beam, and in the absence of noise, the errors in the shear wave speed estimated at the focal depth diminish with distance from the push beam. However, shear wave attenuation also increases sensitivity to noise as the distance from the push beam increases. Time-to-peak and cross-correlation methods consistently achieve much smaller errors with shear wave particle displacements than with shear wave particle velocities. Furthermore, cross-correlations are much more robust with respect to noise, and larger values of the shear viscosity increase the sensitivity of each method to noise.
Experimental characterization of aero-acoustic performance of micro-perforated materials in a wind tunnel
Authors: Maury Cedric , Bravo Teresa , Amielh Muriel , Mazzoni Daniel , Pietri Laurence
Published: December 2020

Mitigating the propagation of low frequency noise in ducted flows represents a challenging task since wall treatments have often limited dimensions. Micro-perforated panels have been successfully used backed by a cavity constituting a bulk-reacting resonator or in combination with honeycomb for a locally reacting system. In this work, a cost-efficient methodology for the study and characterization of the aero-acoustic properties of flush-mounted micro-perforated resonators has been developed. Although Laser Doppler Velocimetry is a non-intrusive technique, it requires delicate instrumentation to obtain an estimation of the acoustic velocity and pressure fluctuations at several points over a wall liner. Here, the attenuation has been estimated from sound pressure level measurements performed with two nosecone microphones positioned along a vertical line centered on the resonator axis. Experiments have been performed in a wind tunnel in presence of a low-speed turbulent boundary layer of air fully developed over different samples made up of micro-perforated sheets or porous materials with surface roughness. The micro-perforates have been flush-mounted over a cylindrical cavity of depth 30 mm situated on the floor of the test section. The ability of bulk-reacting resonators for reducing the acoustic or flow-induced noise has been assessed in comparison with locally reacting treatments.
Propagation and distortion of surface acoustic waves along the boundary of a bimodule medium
Authors: Gusev Vladimir A.
Published: December 2020

The propagation of surface acoustic waves at the boundary of an elastic bimodulus medium is described. The developed model of medium allows to describe acoustic phenomena with non-classical nonlinearity with amplitude-dependent threshold effects, caused by the presence of internal structure such as cracks or polymeric chains. The temporal profile of the surface wave is built. It is shown that this profile in the bimodulus medium is fundamentally asymmetric. This leads to the formation of the unipolar limit profile at large distances.
Nonclassical nonlinearity from dislocation dynamics in resonant vibrations of structures
Authors: Khandelwal Aakash , Chakrapani Sunil Kishore
Published: December 2020

The dislocation string model developed by Koehler, Granato and Lücke has been used to study the contribution of dislocations to the generation of higher harmonics and damping in propagating acoustic waves. The bowing, and subsequent breakaway of dislocation loops at sufficiently high stress amplitudes leads to a stress amplitude dependence of the acoustic nonlinearity and damping. The present work focuses on the development of a model which incorporates the effects of this amplitude dependence in resonant vibration of solid structures. The equation of motion for a harmonically forced nonlinear beam was derived following the classical plate theory, and assuming a material model showing quadratic nonlinearity with linear viscoelasticity. The dislocation contribution was used to express the coefficients in the equation of motion as forcing dependent parameters. The frequency response and resonant frequency shift of the nonlinear beam resulting from the developed model show a deviation from classical nonlinear behavior, including softening-hardening nonlinearity. The models developed here show that the dislocation contribution can be nonclassical in nature.
Stress formalism for elastic waves in anisotropic solids
Authors: Kube Christopher M. , Norris Andrew N.
Published: December 2020

Traditionally, the propagation of bulk elastic waves in anisotropic crystals or solids is governed by the displacement form of the elastodynamic wave equation. Phase velocities follow after transforming the wave equation into an eigenvalue problem, which gives the Christoffel equations, and solving for the roots of the characteristic polynomial. Alternatively, only a few researchers have considered a pure stress wave equation of motion to describe the propagation of waves in elastic solids. However, to our knowledge, the dual characteristic polynomial and its solutions based on a pure stress formalism has not been established previously. This presentation will outline the needed steps to reach and solve the dual characteristic polynomial. Phase velocity solutions follow from the formation of new principal invariants, which are functions of the elastic compliance constants and propagation directions. The dual formalism is proven consistent to the traditional displacement formalism through the use of sixth-rank Levi-Civitia identities. Lastly, possible extensions of this work will be highlighted.
Measuring spatial processing abilities based on attention modulating tasks
Authors: Srinivasan Nirmal Kumar , Charney Lauren
Published: December 2020

Improvement in speech intelligibility can occur when the target talker is spatially separated from competing talkers. Reduction in an individual's hearing ability and working memory (WM) capacity are hypothesized to be two of the major reasons for reduction in performance in a complex listening environment. This study estimated working memory capacity based on a divided attention version of the classic spatial release from masking task using the Coordinate Response Measure (CRM) as speech stimuli. WM capacity was estimated with a speech source presented directly ahead of the listener and two additional speech sources either colocated at 0 deg azimuth angle or symmetrically separated by 30 deg with various amounts of temporal overlap between the speech sources. The listeners were instructed to identify all three color/number combinations presented. Adaptive procedures were used to obtain the maximum amount of temporal overlap at which listeners were still able to correctly identify the speech source presented directly ahead of the listener 50% of the time. Initial analyses of the data indicated strong relationship between SRM and temporal overlap thresholds indicating that SRM is driven by the listeners' ability to modulate their attentional mechanisms.
Effects of steady background noise on benefits from voice pitch differences in a “Cocktail Party” environment
Authors: Oh Yonghee , David Beatrice , Husney Lauren , Lee Sabrina
Published: December 2020

Voice pitch is an important cue for auditory object segregation in a multi-talker environment. A recent study showed that the ability to segregate and identify speech based on voice pitch differences is highly correlated with the breadth of binaural pitch fusion, the perceptual integration of dichotic stimuli that evoke different pitches across ears [Oh et al., ASA (2018)]. The goal of this study was to investigate effects of steady background noise on binaural pitch fusion and speech perception abilities in background noise consisting of multiple talkers. Subjects were tested in both quiet and various “soft” audible noise levels (15, 5, and -5 dB SNR) inboth ears with the following experiments. First, binaural pitch fusion measurements were conducted using pure tones. Second, speech on speech masking performance was measured as the threshold target-to-masker ratio needed to understand a target talker in the presence of either same- or different-gender masker talkers. The results showed that both breadth of binaural pitch fusion was minimized and voice pitch difference benefit in multi-talker conditions was maximized at an optimal amount of the noise levels, which is called suprathreshold stochastic resonance effects. A strong negative correlation was also observed between voice gender benefit and breadth of binaural fusion. The findings suggest potential rehabilitation approaches, such as low-level noise, to sharpen binaural pitch fusion and improve related speech perception ability in multi-talker listening environments.
Importance of temporal cues in audiovisual integration in speech perception in noise
Authors: Yuan Yi , Oh Yonghee
Published: December 2020

There is a long-standing debate in the field of speech perception over the nature of the speech information that is available in the visual input. The overall goal of this project was to establish which visual characteristics can facilitate speech perception in noise, especially in conditions of competing talkers. The central hypothesis is that visual information correlated with the temporal fluctuation of the auditory signal provides audiovisual benefits in speech perception. Unlike previous studies on audiovisual integration where articulatory gestures (i.e., facial and lip movements) were provided as the main source of perceiving speech information, a visual analog of the acoustic amplitude envelope was provided as complementary visual information to degraded auditory signals and manipulated in a series of speech perception experiments in multi-talker babble noises. The first set of experiments investigated whether speech perception in noise can be enhanced only by providing information about the amplitude envelope through a visual analog in various audiovisual coherence conditions: congruent and incongruent. The second set of experiments examined the effects of speech envelope modulation rates on audiovisual speech perception in noise. These results indicate that an abstract visual analog of acoustic amplitude envelopes can be efficiently delivered by the visual system and integrated online with auditory signals to enhance speech perception in noise, independent of particular articulation movements.
Effects of speech and sung speech training on speech prosody production by trilingual children with autism spectrum disorder
Authors: Chen Si , Li Bei , Zhou Fang , Chan Angel Wing Shan , Tang Tempo Po Yi , Chun Eunjin , Choi Phoebe , Ng Chakling , Cheng Fiona , Gou Xinrui
Published: December 2020

Speech prosody can be used to distinguish old (topic) versus new (focus) information and rejecting incorrect alternative statement. It has been reported that children with autism spectrum disorder (ASD) may show abnormal prosody of either monotonic or exaggerated intonation and some of them may fail to mark focus. Though speech and musical training have shown to improve speech production by ASD children, no specific training methods have been proposed to improve the use of speech prosody to mark focus and few studies investigated tonal language speakers. We aim to test (1) whether Cantonese-speaking ASD children fail to mark focus in their native tonal language (2) whether trainings may improve the speech prosody processing (3) whether sung speech training is more effective than speech training? We recruited two training groups of Cantonese-speaking ASD children, a control group of ASD children and TD children. In the training tasks, we focused on improving the mapping between the acoustic cues and information structure. Our pilot results showed that speech and musical training improved the use of prosodic cues such as intensity and f0 in marking focus across various positions. However, ASD children may have difficulties in integrating all the prosodic cues across conditions.
Advancing speech activity detection for automatic speech assessment of pre-school children prompted speech using COMBO-SAD
Authors: Dutta Satwik , Kothalkar Prasanna , Rudolph Johanna , Dollaghan Christine , McGlothlin Jennifer , Campbell Thomas , Hansen John H.
Published: December 2020

Speech sound disorder (SSD), a developmental disorder which affects children's ability to produce the sounds (and words) within their native language, has a prevalence rate of 3%–16% among children in USA. Screening for SSDs generally requires recording, evaluation, and decision-making by a certified speech-language pathologist (SLP). Automating part or all of this process could significantly reduce the amount of time and effort in the screening process. However, in order for this process and especially the final “pass”/“fail” screening decision to be automated, children's speech content must be extracted from within a collected audio sample and therefore requires speech/silence activity detection. For this study, an iOS application for field use was developed to collect speech word productions from children, with algorithmic processing of all participants assigned a Percentage of Consonants Correct-Revised (PCC-R) score by a certified SLP. An unsupervised speech-activity-detection (SAD) algorithm is explored. COMBO-SAD, originally developed during the DARPA-RATS program, was modified to for use on child speech. Model evaluation was performed on a diverse collected child corpus based on their PCC-R score. Finally, a duration “shoulder” extension of SAD boundary labels was also analyzed to benchmark potential system impact on model performance.
Compensating for adaptive beamformer overfitting with random matrix theory
Authors: Buck John R.
Published: December 2020

Capon's Minimum Variance Distortionless Response beamformer requires the ensemble covariance matrix to compute the array weights [Capon, in Proc. IEEE (1969)]. In practice, adaptive beamformers compute their array weights from the estimated sample covariance matrix (SCM). In many scenarios, the environment changes too rapidly for the SCM to be full rank. The Dominant Mode Rejection (DMR) beamformer [Abraham and Owsley, IEEE Oceans (1990)] mitigates this problem by imposing a structure on the eigenvalues of the SCM. DMR assumes that the background noise is spatially white, and enforces this assumption by replacing the weak SCM eigenvaues by their average. However, DMR still must estimate the appropriate subspace dimension for the dominant signals to minimize the expected beamformer output power. Estimating the DMR output power as a function of subspace dimension from the SCM results in a substantial negative bias for the output power caused by overfitting. Random matrix theory results on eigenvector fidelity allow us to approximate this bias in the output power, and compensate for the overfitting. This compensation yields a more accurate estimate of the beamformer output power as a function of subspace dimension. [Work funded by ONR 321US.]
Soundscape Viewer: An integrated toolbox of audio source separation for soundscape-based ecosystem assessment
Authors: Sun Yi-Jen , Lin Tzu-Hao
Published: December 2020

Soundscapes contain collective information on habitat quality and ecosystem dynamics. Current soundscape assessment methods, including clustering and ecoacoustic indices, may deliver unsatisfied performance when multiple sound sources are recorded simultaneously. We introduce an open-source Soundscape Viewer toolbox for separating soundscapes into sounds of biological, environmental, and anthropogenic sources. Based on non-negative matrix factorization (NMF), Soundscape Viewer enables audio source separation in both supervised and unsupervised manners. Conventional supervised NMF learns spectral features from labeled animal vocalizations, yet the performance is sensitive to noise levels. By assuming source-specific periodicity in unsupervised NMF, Soundscape Viewer can learn discriminative features between animal vocalizations and background noise. To cope with dynamic acoustic environments, Soundscape Viewer also integrates adaptive and semi-supervised learning approaches. Adaptive learning improves model generalization when sound characteristics differ from the training data, and semi-supervised learning allows the model to recognize new sound sources. We applied Soundscape Viewer in the evaluation of soundscape dynamics and the automatic detection of animal vocalizations. Our results reveal that the mutual interference between sound sources can be effectively reduced in various ecosystems. Source separation will facilitate biodiversity assessment and increase our understanding of biotic and abiotic sounds' interactions.
A yearlong record of ambient sound on the Chukchi Shelf
Authors: Ballard Megan S. , Sagers Jason D.
Published: December 2020

Studies of ambient sound in the Arctic, both under ice and in the marginal ice zone, have spanned more than 50 years, but rapidly changing conditions with regards to declining ice cover have reduced the relevance of measurements taken in previous decades. Changes in the environment have resulted in changes in the ambient sound field, affecting both the sound generating mechanisms and the sound propagation. From October 2016 to October 2017, the Shallow Water Canada Basin Acoustic Propagation Experiment (SW CANAPE) was conducted on the Chukchi Shelf. One goal of CANAPE was to observe the changing soundscape. This talk presents acoustic recordings collected on the 150-m isobath with the Persistent Acoustic Observation System (PECOS), which contained a horizontal line array of hydrophones along the seabed and a vertical line array spanning a portion of the water column. This study examines the ambient sound level and uses k-means clustering to quantify the occurrence of six unique spectral shapes associated with different seasons and various sound generation mechanisms. The spectral clusters are correlated with environmental observations including sea concentration and thickness, wind speed, and air temperature. [Work supported by ONR.]
Vertical line array measurements of the sound radiated by melting glaciers in Hornsund Fjord
Authors: Vishnu Hari , Chitre Mandar , Glowacki Oskar , Moskalik Mateusz , Stokes M. Dale , Deane Grant B.
Published: December 2020

Marine-terminating glaciers worldwide are melting rapidly in response to climate shifts, resulting in the delivery of freshwater into the oceans. Submarine melting at the glacier-water interface accounts for a significant component of the freshwater delivery from the glacier. This melting produces a distinct acoustic signature, providing a potentially viable modality to monitor glacial ice melting on a large scale via acoustic sensing. In order to evaluate the utility of ambient noise oceanography as a tool to quantify glacial ice-melt, in June 2019 we deployed a vertical hydrophone array and made acoustic measurements at some glacier termini in Hornsund Fjord, Spitsbergen. Quantification via array processing proves to be challenging due to (1) the space- and time-varying sound-speed profile in the underwater channel, and the way it refracts sound in an unknown manner, (2) limited vertical resolution of the array due to its aperture, and (3) interference from other noise sources such as melting icebergs, for example, contaminating the melt sound recordings. We present preliminary results from the processing which reveal different acoustic levels arising from submarine melting at different glaciers. The sound from the melt seems to be more dominant in the upper layers of the water at the glacier-sea interface.
Statistical analysis and modeling of rain-generated ocean noise in the northeast Pacific Ocean
Authors: Schwock Felix , Abadi Shima
Published: December 2020

Large scale studies of underwater ambient noise during rainfall are important for assessing the ocean environment and enabling remote sensing of rainfall rates over the open ocean. In this study, we have evaluated approximately 3.5 years of acoustical and meteorological data recorded at the northeast Pacific Ocean continental shelf and slope. The acoustic data are recorded continuously at a sample rate of 64 kHz at 81 m depth and 581 m depth at the continental shelf and slope, respectively. The wind speeds and rainfall rates are provided by a surface buoy located in the vicinity of each hydrophone. Average power spectra have been computed for different rain rates and wind speeds, and linear and non-linear regression have been performed. The results are comparted between both measurement sites to evaluate the depth dependency of rain noise at the continental margin. In contrast to previous reports, we found that the rain noise levels between 100 Hz and 10 kHz are highly dependent on the prevailing wind speed. Our findings indicate that previously proposed algorithms for estimating rainfall rates from acoustic data are not universally applicable, but rather have to be adapted for different locations.
Novel approach in loudspeaker test stimulus generation using digital methodologies
Authors: Balistreri Riccardo
Published: December 2020

Noise is the most widely used type of signal for acoustic power testing of loudspeakers and audio equipment. It is normally characterised by crest factor, “coloration” and filtering, or power spectral density, for the purpose of approximating the spectral content of music to suite a Device Under Test (DUT). The accustomed way to have equipment generate these signals such as IEC 268-5, EIA 426-B, or pink noise with specified crest factor and bandwidth for use on a DUT, is to first generate white noise, filter by 3dB/oct to get pink noise, then adjust the crest factor by clipping to specified value (some standards show a diagram using diodes), and further filtering, to match the required bandwidth or spectral distribution. This practice is in the opinion of the authors, antiquated. Music is born by natural vibrations and follows more of a gaussian distribution with time varying characteristics and the above-mentioned equipment and processes alter its noise distribution and have little or no time varying characteristics. This paper will place a study on music spectral content, distribution and time varying characteristics and explore synthesis of new signals for loudspeaker and audio equipment testing focusing on easy generation within the digital domain using computers.
Remembering remarkable Larry H. Royster
Authors: Royster Julia D.
Published: December 2020

Larry Royster was a dedicated scientist and engineer whose recognized contributions in the area of noise control and hearing conservation were by no means his only interests. After retiring, Larry's amazing mind was free to follow his fancy into a wide variety of topics. He measured countless phenomena and graphed the results, read nonfiction prodigiously and rated what he read, and wrote summaries for the public about what he was learning. He took up golf and amateur radio with zeal. Liberated from responsibilities that he had always taken quite seriously, he teased his friends and laughed with them. He also reflected on qualities of character that drove him throughout his teaching and research career. In this presentation I will share sides of Larry that were not obvious to many.
Infrasound measurements of tornadoes and other severe storm events at close range
Authors: White Brandon , Lindsey Bryce , Faruque Imraan , Elbing Brian R.
Published: December 2020

Recent experimental evidence suggests that, during tornadogenesis and through the life a tornado, acoustic waves at frequencies below human hearing (infrasound) are produced. To date, acoustic data required to identify the fluid mechanism responsible for this infrasound has been limited—often gathered by large fixed installations. The design and deployment of a mobile Ground-based Local Infrasound Data Acquisition (GLINDA) system was completed at Oklahoma State University to expand the number of samples and enable close-range measurements which would mitigate the measurement uncertainty associated with long distance atmospheric propagation. GLINDA has been deployed alongside Oklahoma-based media storm chasers since May 2020 and has already returned data over multiple severe weather events, including tornadic measurements acquired with GLINDA on 22 May 2020 in Lakin, Kansas. The GLINDA-equipped storm chaser vehicle can additionally provide acoustic data on other weather events such as wildfires and winter weather storms as the vehicle is appropriate for sustained, close observation of these environments. This presentation will cover system design, measurement capabilities, and acoustic production by select weather phenomenon.
Nonlinear reflection coefficient of finite amplitude waves
Authors: Khandelwal Aakash , Bilgunde Prathamesh , Barnard Daniel , Chakrapani Sunil Kishore
Published: December 2020

Ultrasonic waves incident at the interface between two linear media will be reflected based on the linear reflection coefficient, which depends on the linear acoustic impedances of the media. However, propagation of ultrasonic waves in quadratically nonlinear media can lead to nonlinear reflection coefficients which are dependent on the frequency, source amplitude, and nonlinearity of the two mediums. The objective of this work is to explore the existence of a nonlinear reflection coefficient between two mediums using analytical, numerical, and experimental methods. For simplicity and consistency, a water-solid interface was chosen and finite amplitude ultrasonic waves between 2.25 MHz and 25 MHz were used to study the interfacial response. The analytical results show the existence of a nonlinear RC, but whose effect is very minimal. Experimental and numerical results show that the transfer of energy in harmonic generation affects the RC more than other factors. The influence of several factors like interaction zone, shock generation, etc. will be discussed.
Nonlinear dispersive waves in 2-D micropolar lattices
Authors: Wallen Samuel P. , Haberman Michael R.
Published: December 2020

Architected materials, also known as mechanical metamaterials, are solid structures designed by leveraging geometry, rather than composition, to achieve desired mechanical properties. Past studies on mechanical metamaterials have demonstrated properties that are rare or absent in naturally occurring materials, such as negative Poisson's ratio, chirality, and extremely high ratios of bulk to shear modulus and strength to weight. Most of the existing literature on architected materials has been focused on linear behavior, though some works have incorporated nonlinearity, often leveraging mechanical instabilities to re-configure a lattice. In the present work, we explore nonlinear dispersive waves in 2-D architected lattices with rotating microstructure, which are man-made analogues of nonlinear micropolar continua. Specifically, we consider a discrete model that consists of a periodic array of rigid bodies connected by nonlinear springs, focusing on theweakly nonlinear dynamic regime. For wavelengths much longer than the characteristic lengths of the microstructure, we demonstrate that the nonlinear behavior of longitudinal and transverse acoustic wave modes may be described by evolution equations of the Kadomtsev-Petviashvili type, which include effects of weak nonlinearity, weak dispersion, and weak transverse variation. Solutions of these evolution equations will be discussed and compared with direct numerical simulations of the discrete lattice.
The effect of virtual reality environments on auditory memory
Authors: Shamei Arian , Gick Bryan
Published: December 2020

Auditory recall is stronger in the environment in which a memory was originally encoded, an effect of context-dependent memory (CM) [Godden and Baddeley, Brit. J. Psychol.66(3), 325–331 (1975)]. Innovations in virtual reality (VR) have resulted in the adoption of VR as a communication platform in professional, medical, and educational contexts. The present study reports an experiment testing how CM impacts auditory memory across differing VR environments. An experiment will be described in which participants in one of two distinct virtual environments (e.g., beach and forest) within the VR-communication platform AltSpace hear three iterations of a pre-recorded list of 16 words controlled for frequency and syllable count. Participants are tested for recall of the word-list in either the same or the differing virtual environment. Improved accuracy when tested in the same environment would suggest that CM can be observed for auditory memory between virtual environments. Preliminary results indicate a potential context-dependent effect between virtual environments. Results will be discussed, with implications for professional, medical, and pedagogical applications in virtual settings.
Enhanced memory for sentences read aloud conversationally versus clearly: Evidence from sentence recognition memory and recall
Authors: Keerstock Sandie , Ballard Frida , Smiljanic Rajka
Published: December 2020

Native and non-native listeners were more accurate in identifying sentences as previously heard and in recalling words and entire sentences when they heard clear speech compared to conversational speech (Keerstock and Smiljanic, 2018, 2019). This clear speech benefit on listeners' memory might in part be due to decreased listening effort in perceiving intelligibility-enhancing clear speech (“effortfulness hypothesis,” Rabbitt, 1968). The effect of reading sentences aloud in clear speech on talkers' memory, however, is unknown. We hypothesized that the effort required to produce clear speech could detrimentally affect memory encoding. In the present study, native and non-native English speakers read sentences aloud in clear and conversational speaking styles. Their memory of the read sentences was assessed either via a sentence recognition memory task (Experiment 1; n = 90) or a recall task (Experiment 2; n = 75). Results from both experiments showed superior retention of spoken information for sentences read aloud conversationally rather than clearly. The results indicate that producing clear speech, unlike perceiving it, interferes with sentence recognition memory and recall. Production of listener-oriented hyper-articulated speech may increase cognitive load leaving fewer cognitive resources available for storing spoken information in memory.
The impact of question prosody during parent-child interactions in a museum setting
Authors: Thorson Jill C. , Trumbell Jill M. , Nesbitt Kimberly
Published: December 2020

Children museums provide a dynamic environment for families to engage in learning, with exhibits designed to enhance and stimulate caregiver-child interactions (Marcus, 2016; Willard et al., 2019). Additionally, it has been shown that the use of specific types of questions supports narrative development and critical thinking by scaffolding more elaborative responses (Reese and Fivush, 1993). The motivation for this study is to analyze the prosody of wh-questions during caregiver-child interactions in an ecologically valid settingâ€”a children's museumâ€”with the goal of better understanding how the prosody of questions may impact language during learning-based free play. Specifically, we examine wh-questions during 20-min exhibit explorations by 3- to 6-year old children with their caregivers (n = 10). Caregiver and child wh-question prosody is analyzed phonologically (pitch accents and boundary tones) and acoustically (F0). Outcome measures additionally include the overall amount and types of child language produced. We hypothesize that caregiver prosody will be reflected in that of the child, with a correlation between more expressive caregiver prosody and the overall amount of language produced by the child. The broader research aim is to provide strategies to caregivers to increase language output and enhance learning during museum experiences.
A comparison of the production of phonetic variants of /t/ in child-directed speech versus adult-directed speech
Authors: Fritche Robin , Shattuck-Hufnagel Stefanie , Song Jae Yung
Published: December 2020

The surface phonetic details of an utterance affect how ‘native' a speaker sounds. However, studies have shown that children's acquisition of context-appropriate variation (sometimes called allophones) is late. This study's goal was to understand how caregivers use phonetic variation in the production of American English /t/ in child-directed speech (CDS), compared to in adult-directed speech (ADS). We hypothesized that mothers modify their input to children in order to produce more limited variation in CDS than in ADS, to potentially assist children in the development of contrastive phonemic categories. To this end, we recorded eight mothers of children under the age of 2 years in both ADS and CDS conditions. Results reveal that CDS contains significantly more canonical cues to /t/ than ADS does, and fewer non-canonical cue patterns, including fewer unreleased tokens in utterance-finally and fewer glottalized tokens both utterance-medially and utterance-finally. Also, in utterance-medial position we found larger aspiration duration differences in CDS between aspirated singleton /t/ vs. unaspirated /t/ in /st/ contexts, suggesting that mothers exaggerate this cue to the phonemic context in which the /t/ occurs. Overall, the finding of more limited variation in CDS may help explain why children produce canonical forms before producing phonetic variants.
Tonal carryover assimilation is exploited as a speech segmentation cue when cues conflict
Authors: Guo Zhe-chen
Published: December 2020

Tonal carryover assimilation, whereby a tone is phonetically assimilated to the preceding one, is widely observed across tone languages. This tonal coarticulatory effect is stronger across a smaller prosodic boundary (Lai and Kuang, 2016), suggesting that it may be a speech segmentation cue. The possibility was investigated in two artificial language (AL) learning experiments. Mandarin-speaking participants listened to long utterances in which tokens of the “words” of a three-tone AL (e.g., [pé.tț.kù]) were concatenated without pauses and then identified the words in a test. The first experiment revealed that segmentation was disrupted in an “incongruent-cues” condition where tonal carryover assimilation occurred across AL words in conflict with statistical regularities. Segmentation was neither improved nor inhibited in a “congruent-cues” condition where tonal carryover assimilation occurred within AL words but in only 27% of the word tokens. A follow-up experiment that included a similar congruent-cues condition but maximized the number of cue-bearing word tokens still found a null effect. It is concluded that tonal carryover assimilation is exploited to segment speech in the case of cue incongruence. Yet, it seems redundant when it agrees with statistical regularities, possibly because it is weighted low in the segmentation cue hierarchy (Mattys et al., 2005).
The perception of English words with consonant clusters and vowel deletion by young normal-hearing listeners under noise
Authors: Iwagami Eri , Arai Takayuki
Published: December 2020

In this study, we investigated whether the misperception rate of English words with consonant cluster and vowel deletion increase under noise simulated age-related hearing loss. A perception experiment was conducted for young normal-hearing listeners, British English native speakers, in both noise and no-noise conditions. We used real English words were used as target words for this experiment which have consonant clusters in the word-initial and word-final (Type1) and that vowel deletion can occur in first or second vowels (V1 and V2) (Type2). These words were produced and recorded by a male British English native speaker, and the speech sounds were used as the stimuli of this experiment. V1 or V2 in Type2 was produced with deletion and non-deletion. The results showed that the misperception rate of words of Type1 and Type 2 with deletion increased in the noise condition. However, the misperception rate was greater for Type2 with deletion than Type 1 in the noise condition, suggesting vowel energy is important to perceive English words in the noise condition. Hence, the misperception rate by elderly English native listeners is expected to increase for these words as well this result in the simulation of age-related hearing loss.