bluuebunny/crossref_metadata_2025 huggingface dataset:
Overview of UK Policy and Research Landscape Relevant to Deploying Advanced Nuclear Technologies in the UK
Authors: Underwood Nicholas , Nevitt Paul , Howarth Andrew , Barron Nicholas
Published: December 2020

The UK government is committed to tackling climate change through clean growth — cutting emissions while seizing the benefits of the low carbon economy [1,2]. In June 2019 UK government set a legally binding target to achieve net zero greenhouse gas emissions from across the UK economy by 2050. Nuclear energy is seen as a vital contributor to decarbonising the UK economy as outlined in the Industrial Strategy [2] and subsequent Nuclear Sector Deal [3], and £180 million of funding has been provided by Government for a Nuclear Innovation Programme (NIP) over the period 2016–21, administered through the Department for Business, Energy and Industrial Strategy (BEIS).

Initial phases of the NIP have researched advanced nuclear fuel cycles, digital reactor design methods and advanced materials and manufacturing techniques. Throughout this programme the UK has developed a better understanding of a range of Advanced Nuclear Technologies (ANT), including Advanced Modular Reactors (AMRs) and the opportunities that they provide in decarbonising a future energy system. In parallel, UK government has established a policy framework designed to encourage the development of Advanced Nuclear Technologies [4] and awarded an initial phase of development for a Small Modular Reactor (SMR) [5]. These programmes of work are enabling the development of technologies towards commercialisation, whilst enabling regulations are advanced.

For this paper, AMRs are defined as a broad group of advanced nuclear reactors which differ from conventional reactors that use pressurised or boiling water for primary cooling. AMRs use novel cooling systems or fuels and in order to achieve operational efficiencies and enhanced safety performance, they are typically planned to operate in harsh conditions, including high temperatures, radiation field and corrosive environments. As a result of this there are still many questions which need addressing in relation to how materials and fuels will perform in these more extreme conditions. Within the NIP, an Advanced Manufacturing and Construction initiative is supporting answering these questions.

This paper provides an overview of the policy and research landscape that aims to bring AMR and SMR technologies to deployment in the UK, and how the Advanced Manufacturing and Construction initiatives are helping to underpin the R&D needs for AMR deployment in the UK. One example is a programme of work titled “Establishing AMR Structural Integrity Codes and Standards for UK GDA” (EASICS). The aim of this project is to establish guidance on the structural integrity codes and standards that are required to support the Generic Design Assessment (GDA), which is a UK licensing process, of an AMR design through technology innovation and transfer (primarily for high temperature reactors). An overview of project EASICS will be described in further detail in another paper presented at PVP2020, PVP2020-21721.
Fatigue Failure Predictions Based on FEA Fracture Mechanics Simulations
Authors: de Haan - de Wilde F. H. E. , Hannink M. H. C. , Blom F. J.
Published: December 2020

Fatigue is an important ageing mechanism for long-term operation (LTO) of nuclear power plants. The effect of the reactor coolant environment on fatigue is one of the factors to take into account. Application of environmental fatigue codes, generally, leads to large margins for actual fatigue failure of components. In combination with longer operation times, these margins can make it challenging to meet the criteria defined in the standards. The purpose of the work in this paper is, therefore, to gain insight into the conservatism in typical fatigue analyses using design fatigue curves which is done by analyzing the fatigue process up to the actual component failure using crack growth analyses.

Prediction of fatigue failure in cylindrical specimen is investigated through numerical simulations of fracture mechanics. A finite element analysis model is implemented for a crack in a cylindrical specimen typically used for fatigue life testing and generating design fatigue curves. The specimen is uniaxially displacement-loaded into the plastic regime, and the reaction force is evaluated as a function of crack depth and shape. Cyclic loading leads to formation of a crack with the depth such that a failure point in the S-N curve corresponds to the 25% load drop. Stress intensity factors are calculated, and number of cycles to failure are determined based on Paris’ law and a two-stage crack growth relationship. Simulation results are compared to experimental fatigue life data and show good agreement. The outcome of the investigation can be extended to fatigue life of geometrically complex thermo-mechanical components, such as nozzles, under transient thermal loading occurring during operation of a nuclear power plant, in order to assess conservatism of fatigue failure criteria based on experimentally obtained S-N design curves.
New species of the genera Lupaeus and Rubroscirus (Acari: Cunaxidae) from Southern Brazil

Authors: Wurlitzer Wesley Borges , Johann Liana , Ferla Noeli Juarez , Da Silva Guilherme Liberato
Published: December 2020

Two new species of Cunaxidae from Brazilian Atlantic Forest biome are described. Lupaeus stolli Wurlitzer & Ferla sp. nov. was collected from Varronia curassavica Jacq. (Boraginaceae), in Santa Catarina state, and Rubroscirus grilloi Wurlitzer & Ferla sp. nov. from Vernonanthura tweediana (Baker) H. Rob., soil and leaf litter, in Rio Grande do Sul state, Brazil.
A new measurement of the deepest depth of the ocean
Authors: Loranger Scott , Barclay David R. , Buckingham Michael
Published: December 2020

Scientists and explorers have been searching to determine the exact location and depth of the deepest part of the ocean since the HMS Challenger made the first sounding of the Mariana Trench in 1875. The consensus is that the deepest abyss in the ocean is in the Challenger Deep, a portion of the Mariana Trench with depths greater than 10 000 m. Since the HMS Challenger II returned to the Mariana Trench in 1952, 14 estimates of the deepest depth of the ocean have been made. Estimates of the location and maximum depth are as diverse as the methods used including wire soundings, explosives, single and multibeam sonars, and remotely operated and manned submersibles. During an Office of Naval Research supported expedition to the Challenger Deep in 2014, two free falling passive acoustic instruments were deployed. The implosion of one instrument was recorded by the other when both were at depths greater than 8000 m. Multiple reflections from the seafloor and sea surface of the sound generated by the implosion were used to determine the depth of the Challenger Deep. The result was the most constrained estimate of the deepest part of the ocean, 10 991 ± 6 m.
A classification approach to the characterization of seabed geoacoustic profiles via deep learning
Authors: Forman David J. , Neilsen Tracianne B. , Van Komen David F.
Published: December 2020

Acoustic source localization algorithms in the shallow ocean require information about the ocean seabed. While past approaches have characterized seabed geoacoustic profiles via continuous physical parameters, a classification approach approximates the distribution of seabed types as a discrete set of seabed classes. To exclude acoustically indistinguishable seabeds from the discrete classes, the acoustic separation between two seabeds may be evaluated by the Pearson correlation between their characteristic transmission loss curves. This process yields a subset of discrete seabed classes. To distinguish these classes, we train a convolutional neural network classifier on the pressure time-series of SUS charges, which are simulated using the geoacoustic profiles of the seabed classes. This network successfully predicts seabed class, when tested on a holdout set where the sound speed profiles of the ocean are adequately similar to those in the training set. An acoustic separation measure between sound speed profiles, analogous to the one for seabeds, directly relates to the generalization error of the network. [Work supported by the Office of Naval Research Contract No. N00014-16-C-3065 and by the NSF REU program, Grant No. 1757998.]
Neural networks as an applied tool for ultrasound beamforming and image reconstruction
Authors: Dahl Jeremy , Hyun Dongwoon
Published: December 2020

In recent years, the computer science community has made available its artificial intelligence tools to the public at-large. Freely available online courses, software libraries, and databases have made it easy to incorporate artificial intelligence, and specifically machine learning, into many research areas. In medical imaging, this has led to a proliferation of machine learning-based research methodologies in image reconstruction tasks, whether appropriate or not. In this lecture, we review machine learning as a tool for ultrasound beamforming. We discuss the selection of an appropriate problem to be solved with machine learning, survey common and popular implementations of neural networks, and describe best practices and common pitfalls. We visit a few misconceptions about machine learning in ultrasound imaging and examine the recent literature in the field of ultrasound beamforming and image reconstruction.
Ultrasound beamforming using deep networks
Authors: Byram Brett , Tierney Jaime , Berger Matt
Published: December 2020

Medical ultrasound exams contain substantial diagnostic information, but in many patients this information is obscured by various sources of degradation. Previously, we demonstrated that physical-model based beamforming methods could improve ultrasound image quality. This was important because it demonstrated that beamforming could be posed as a nonlinear regression problem, indicating that deep neural networks (DNNs) might also represent a beamforming solution. Based on this, we began developing such DNNs for ultrasound beamforming and showed that they did indeed lead to consistent improvements in simulation, phantom and in vivo data. For this effort, we considered several aspects of DNN training, including loss functions, optimization strategies, architectures and training data. The nature of the training data and loss functions exhibited the most substantial impact on performance. Acquiring appropriate training data is challenging because there are no existing curated data sets for beamforming, so we relied heavily on simulations, which can be carefully controlled to enable precise separation of signal and clutter. We also considered training with data acquired from phantoms where the signal and clutter could be easily separated. With respect to loss functions, we considered classic DNN methods, but we also recently developed dedicated, ultrasound motivated loss functions to good effect.
3-D photoacoustic tomography reconstruction with deep learning for vasculature imaging
Authors: Guan Steven , Chitnis Parag V.
Published: December 2020

Photoacoustic tomography (PAT) is a hybrid imaging modality capable of acquiring high contrast and resolution images of optical absorption at depths greater than traditional optical imaging techniques. Practical considerations with instrumentation limit the number of acoustic sensors and their “view” of the imaging target, which result in image reconstruction artifacts degrading image quality. Iterative reconstruction methods can be used to improve image quality but are computationally expensive, especially for 3-D PAT over large imaging volumes. Deep learning has emerged as an efficient alternative and is capable of achieving state-of-the-art performance. In this work, we compare the 3-D fully dense UNet convolutional neural network with the widely used time reversal reconstruction method. Simulated acoustic data was generated using the K-wave MATLAB toolbox (225 detectors, planar geometry). A public database containing 50 patient's whole-lung CT scans was used to create training (n = 40) and testing (n = 10) data. The training and testing datasets are comprised of 500 and 50 lung vasculature volumes sampled from their respective whole-lung CT scans. Using the structural similarity index, the proposed deep learning method (0.87 ± 0.04) is shown to be superior to time reversal (0.38 ± 0.11).
Weight for it… adaptive beamformers in passive acoustic mapping for cavitation imaging
Authors: Gray Michael , Coviello Christian , Gyongy Miklos , Lyka Erasmia , Paverd Catherine , Crake Calum , Elbes Delphine , Smith Cameron , Coussios Constantin
Published: December 2020

As the applications of therapeutic ultrasound expand across neurological, oncological and musculoskeletal medicine, monitoring of cavitation activity offers the potential for non-invasive treatment guidance and optimization of safety and efficacy. When implemented with a distributed set of sensors, simple delay and sum beamformers can be effective for cavitation source detection, but localization and quantification capabilities may be hindered when using conventional diagnostic ultrasound arrays. More generally, when observations of the emitted field are limited by the quantity, bandwidth, and geometric distribution of the receivers employed, and/or are subject to uncertainties in array calibration and signal propagation path, â€˜robust' data-adaptive beamformers can offer considerable improvements in the estimation of emission source properties. This paper reviews the concepts of adaptive beamformers—wherein outputs are calculated using data-dependent receiver weights—and their application to cavitation monitoring. Examples are presented for two such beamformers used in our laboratory, demonstrating their enhanced imaging capabilities, their relative computational cost, and the physical interpretation of their optimized weights. Finally, we discuss clinical translation of these techniques, critical factors in quantitative data interpretation, and how beamformed data can be used to estimate and correct for in vivo propagation effects.
Passive acoustic mapping utilizing compressed-domain processing for real-time monitoring of cavitation-enhanced drug delivery
Authors: Crake Calum , Boulos Paul , Power Maura , Ellis Edward , Monnier Florian , Polcaro Alessandro , Kozick Richard , Coviello Christian
Published: December 2020

Ultrasound-induced cavitation has been shown to improve the delivery of a range of therapeutics including small-molecule drugs, oncolytic viruses and immunotherapies, potentially enhancing their delivery and reducing their toxicity for treatment of solid tumours. Real-time monitoring methods such as passive acoustic mapping (PAM) may be employed to map cavitation activity during treatment. However, while advances in acquisition hardware facilitate outstanding monitoring capability, transfer, storage and processing of the resulting data remains a challenge. Previously we investigated the use of compressed sensing (CS) techniques to sparsely reconstruct full-rate time-series array data for subsequent conventional PAM. Here we extend this approach to directly perform PAM using the compressed-domain (or CS) data. In our approach the CS data is obtained from projections that jointly compress the full-rate array data. The PAM image is computed directly from the CS data using a sparse matching pursuit algorithm, with a dictionary formed from a discretized model using a reference sensor. Results showing accurate localization of cavitation activity using CS-PAM are obtained with simulated and in-vivo (porcine) measured data but processing only 1% of the full-rate data. Finally, common issues with voxel grid density that affect source localization in CS-PAM and conventional PAM are highlighted.
A nonlocal boundary condition for domain truncation in frequency-domain Helmholtz problems
Authors: Kirby Robert C. , Kloeckner Andreas , Sepanski Ben
Published: December 2020

Numerical resolution of exterior Helmholtz problems requires some approach to domain truncation. As an alternative to approximate nonreflecting boundary conditions and invocation of the Dirichlet-to-Neumann map, we introduce a new, nonlocal boundary condition. This condition is exact and requires the evaluation of layer potentials involving the free space Green's function. However, it seems towork in general unstructured geometry, and Galerkin finite element discretization leads to convergence under some mesh constraintsimposed by Garding-type inequalities. We will sketch this method, show how we have integrated Firedrake with pytential (a fast-multipole code), and discuss what issues this raises for extending Firedrake to work with more general nonlocal operators.
Quantification of error bounds for model truncation
Authors: Bonomo Anthony L. , Craun Matthew
Published: December 2020

Many computational techniques have been developed to approximate the Sommerfeld radiation condition for finite computational domains. Recently, two such techniques (the perfectly matched layer and an easier-to-implement alternative dubbed the “reasonably” matched layer) have been used to truncate extended structures, treating these structures as semi-infinite in an attempt to extend the applicability of the finite element method to higher frequencies. In order for this model truncation method to be truly useful, however, a means to predict the error due to this semi-infinite assumption must be readily available. In this presentation, the mean-value method of Skudrzyk is revisited and utilized to make a priori error estimates that bound the excursion of the true solution from that obtained using model truncation. Error bounds for both structure borne vibration and sound radiation are considered. [Work supported by ONR.]
A finite element-based mode-matching technique for computation of the scattered wave fields from spatiotemporally modulated elastic media
Authors: Goldsberry Benjamin M. , Wallen Samuel P. , Haberman Michael R.
Published: December 2020

Previous work by the authors provided the derivation and implementation of a finite element approach to model nonreciprocal elastic wave propagation for media in which the material properties are functions of both space and time [Goldsberry et al., J. Acoust. Soc. Am. 146(1) (2019)]. That work employs a harmonic balance approach to calculate propagating modes in a periodic medium. The present work adapts the aforementioned finite element approach to compute the scattered elastic wave field from finite structures having spatiotemporally modulated material properties. Calculation of the scattered field requires a domain truncation technique that accounts for the radiating modes at each generated harmonic of the modulation frequency. We derive and implement a mode-matching boundary condition using a Galerkin framework, which weakly enforces the continuity of the stresses and displacements at the boundary between the computational and the exterior analytical domain. We show that this approach is similar to a Dirichlet-to-Neumann boundary condition. Finally, we demonstrate this domain truncation technique as a means to compute the reflected and transmitted elastic wave fields from a proposed nonreciprocal elastic wave circulator design. [Work supported by NSF EFRI.]
Sound barriers from stoics to simplex and from optics to acoustics
Authors: Rosenhouse Giora
Published: December 2020

The design of finite sound barriers near numerous noise sources and control points needs many calculations, especially when optimization is required. Since the problem involves geometry that combines generalized triangles and quadrilaterals, the use of simplex theory seems to be effective. It was developed by Dantzig (1914–2005) for linear programming. This is one of the most influential algorithms in science, engineering and arts. In many situations, the basic simplex forms can support analysis of insertion loss (IL) of relatively complicated sound barrier forms by applying trigonometric relations of the basic simplices as suggested here. Specific known data of simplices (sides, angles, areas, volumes) solve additional unknowns of a whole 2-D or 3-D grid or part of it. Such calculations can apply vector analysis to define the angle size and the location of points in the simplical complex which is necessary as data for finding IL and other issues of environmental acoustics. We will show solutions of IL, including “Maekawa–Pierce triangle” in wide barriers, finite barrier analysis by combined triangles, combined passive—electro acoustic with passive anti-noise protection and Scholes-Sargent graphs of IL at the shadow zone of a bridge, expressed by the shadow angle of the control point.
Aerogel two ways: Towards ultralight noise absorbers
Authors: Sharma Bhisham , Lin Dong , Dasyam Amrutha , Yang Guang
Published: December 2020

Aerogels are a class of synthetic materials that are derived by using supercritical drying to extract the liquid component of a gel and replacing it with gas. This process results in the formation of an ultra-lightweight nanoporous solid composed of up to 99.98% air by volume. In this talk, we explore the possibility of developing aerogel-based ultralightweight sound absorbers in two different forms. First, we focus on the acoustic characterization of aerogel granules. The absorption properties of four different aerogels with granule diameters ranging from 2 to 4000 μm and granule densities ranging 120 to 180 kg/m3 are presented. Next, we discuss the additive manufacturing of aerogel-based sound absorbers using a freeze casting method. This novel method allows the fabrication of solid aerogel structures with controlled microstructural properties. The sound absorption and transmission loss properties of 3-D printed aerogel samples are measured using an impedance tube setup. We demonstrate that such structures can provide significantly higher absorption and transmission loss properties as compared with current passive noise reduction materials. [Work Sponsored by NASA EPSCoR.]
An acoustic evaluation of light weight granular porous materials for urban air mobility applications
Authors: Kenchappa Bharath , Shivakumar Kunigal
Published: December 2020

Soon Urban Air Mobility (UAM) vehicles will become a reality. The UAM vehicles need to be safe, environmentally clean, quieter and affordable. Air vehicle noise and reduction of it is a major challenge in urban areas, where these vehicles are needed the most. This paper attempts to develop a lightweight noise absorbing material system using porous particles constructed such that one can have varying pore size, its distribution, surface roughness, tortuosity, and layering. Analytical modeling is used to develop material model consisted of special hollow microbubbles, aerogel granules and other lighter weight materials. These partials are bonded by coating with a very thin layer of binder and processed to produce different structural constructions. The target is to achieve at least 50% sound absorption and 15 dB transmission loss. Several designed material systems will be validated by impedance tube testing. Details of modeling, development of materials, test and test results will be discussed in the full paper and in the presentation.
Enhanced low frequency broadband dissipation using micro-capillary plates
Authors: Bravo Teresa , Maury Cedric
Published: December 2020

Helmholtz-type resonance absorbers constitute noise control devices widely used in many areas that have attracted attention in the last years due to the advancement of acoustic metamaterials. Micro-perforated panels placed over a backing cavity work on the same principle at low frequencies. They can provide important absorption values but confined in a narrow frequency band. To overcome this limitation, unbacked configurations have been considered, but care has to be taken for a proper selection of their constitutive parameters. In this work, freestanding micro-perforated plates with holes diameters down to 10 micrometers and high perforation ratio are shown to be good candidates as wideband low-frequency sound absorbers. Several micro-capillary plates, classified as a function of the Knudsen number, are studied analytically and experimentally. Most of the porous microsystems that use gases work in slip-flow regime whose properties differ considerably from the classical continuum regime. Results showed that unbacked micro-capillary plates can achieve absorption values greater than 0.7 up to 7 kHz with an absorption plateau above 0.85 up to 4 kHz under normal incidence. Dependence of their performance to the backing load is analyzed. They could be used as low-frequency noise dissipation devices with applications as calibrated anechoic terminations.
Adaptive model-based control of traveling wave in a dispersive impedance tube
Authors: Vered Yoav , Bucher Izhak
Published: December 2020

Impedance tubes are the preferred instrument for measuring the acoustic properties of specimens in fluidic mediums. It is shown that the accuracy of the estimation improves by manipulating the boundary impedance of the tube. By means of digital control, a wide range of boundary impedances can be realized showing greater flexibility than passive termination. This is crucial especially when regarding a wide frequency range. In the realistic case of an elastic waveguide, multiple dispersive modes propagate simultaneously at all frequencies. Boundary control should, therefore, account for the modes and their dispersive nature. In this paper, the tube boundary impedance is being tuned as desired by using two loudspeakers, one at each end. The suggested method accommodates the dispersive behavior by estimating, in real-time, a parametric reduced-order model using an adaptive algorithm. A nonlinear control law is employed, capable of tracking the desirable modal traveling wave ratio. An experimental case-study utilizing an air-filled impedance tube is described. The results demonstrate the proposed approach's ability to control the dynamics of the principal acoustic mode, enable to create any combination of standing or traveling waves along the tube.
Nonlinear torsional wave propagation in a thin circular rod
Authors: Cormack John M. , Hamilton Mark F.
Published: December 2020

Coupled nonlinear wave equations are obtained for the special case of wave motion in a thin rod with circular cross-section resulting from a large-amplitude torsional source. Lagrangian mechanics are employed to obtain the wave equations from expressions for the kinetic and potential energy densities in the rod due to an assumed displacement field. Longitudinal waves are generated at quadratic order in strain by the torsional wave through inertial (centrifugal) and elastic forces. Nonlinear effects on the torsional wave occur at cubic order in strain, due to both interaction with the longitudinal wave and strain-hardening shear nonlinearity. While the torsional wave propagates without dispersion, the longitudinal wave is subject to leading-order effects of geometrical dispersion when its wavelength is comparable to the rod radius. The case of weak nonlinearity is analyzed, for which the torsional wave propagates without nonlinear distortion while finite-amplitude effects generate a longitudinal wave. An analytical solution reveals that inertial and elastic forces resulting from a harmonic travelling torsional wave work against each other in the generation of the longitudinal second harmonic. Numerical solutions for transient source motion highlight interaction between the torsional and longitudinal modes near the source, and effects of geometrical dispersion on the longitudinal wave.
Investigating the parameters of temporal integration in pitch
Authors: Mehta Anahita H. , Oxenham Andrew J.
Published: December 2020

The pitch of the fundamental frequency (F0) can be elicited by presenting a sequence of short consecutive individual harmonics embedded in a background of noise. We conducted a series of experiments to determine the spectro-temporal properties under which this virtual pitch could be perceived. We also investigated the factors that influence the length of the maximum time window of integration for virtual pitch. F0 difference limens (F0DLs) for sequentially presented components in noise were measured in 15 normal-hearing participants. The conditions measured included harmonic and inharmonic, as well as components that would normally be spectrally resolved or unresolved when presented simultaneously. Temporal parameters included inter-tone interval (ITI) and tone duration. F0DLs in the various sequential conditions were compared with F0DLs using complex tones with simultaneously presented components. The results suggest that the percept is absent when only high-numbered harmonics (>10) that are resolved due to being sequential are presented as well as when the tones are inharmonically related. Results also suggest that the length of the window of integration does not differ across manipulations of ITI or tone length for resolved harmonic complexes. These results provide a unique understanding of temporal integration and resolvability in pitch through this illusory percept. [Work supported by NIH grant K99DC017472 (AHM) and R01DC005216 (AJO).]
Effects of silent interstimulus interval duration between precursor and target stimuli on spectral context effects in vowel and consonant categorization
Authors: Stilp Christian , Winn Matthew B.
Published: December 2020

When spectra differ between earlier (precursor) and later (target) sounds, listeners perceive larger spectral changes than are physically present. For example, when precursor sounds (e.g., a sentence) possess relatively higher frequencies, the target sound (e.g., a vowel sound in the final word) is perceived as possessing relatively lower frequencies, and vice versa. These spectral contrast effects (SCEs) have been widely reported to influence auditory perception most broadly. Broadbent and Ladefoged (1960) reported that SCEs influenced vowel categorization across varying silent interstimulus interval (ISI) durations between precursor and target sounds, with effect magnitudes appearing to decrease as ISI duration increased. Here we extended this investigation as listeners categorized vowels (/I/-/ε/ as in “bit” and “bet”) or consonants (/d/-/g/) following a context sentence with relevant frequencies amplified to produce SCEs. Precursor filter gain was + 20 dB or + 5 dB to produce larger or smaller SCEs, respectively. ISI durations were logarithmically spaced (50, 150, 450, 1350 ms). SCE magnitudes generally decreased as ISI increased. Larger SCEs decreased more quickly than smaller SCEs at longer ISIs, providing further specification to Broadbent and Ladefoged's findings. Results are consistent with the mechanisms thought to underlie SCEs, neural adaptation in both the peripheral and central auditory system.
Comparing word and emotion recognition by listeners with normal hearing using unprocessed and vocoded speech stimuli
Authors: Morgan Shae D.
Published: December 2020

Current cochlear implant processing strategies preserve acoustic information necessary for speech recognition (e.g., the amplitude envelope), but significantly degrade spectral information in a signal. Listeners utilize changes in spectral information to form social judgments about a talker, such as determining the talker's sex or emotional state. Individuals with cochlear implants may be disproportionately disadvantaged when identifying this social speech information using auditory cues alone, given the device's processing emphasis on preserving word recognition only. This presentation compares the recognition of words and emotions in speech using unprocessed speech as well as speech processed using an 8-channel noise vocoder to simulate listening with a cochlear implant. We discuss the comparison of word recognition with emotion recognition for unprocessed and processed conditions across several signal-to-noise ratios (SNRs). Results indicate that emotion recognition is better than word recognition at similar SNRs, and that vocoded word and emotion recognition is poorer than when stimuli are unprocessed. The data suggest that emotion recognition is disproportionately and negatively affected by CI processing compared to word recognition.
Neural and behavioral correlates of change detection following training with complex auditory scenes
Authors: Ball Natalie J. , Wisniewski Matthew , Simpson Brian D. , Mercado Eduardo
Published: December 2020

The effects of training on an auditory flicker task were examined in this study, where auditory scenes alternated until a participant responded “change” or “same.” Change scenes differed in the location (on the horizontal plane) of two or more sounds. Half of participants were trained with auditory scenes on Day 1, and half were trained on a visual task. On Day 2, all participants were tested on auditory scenes containing either trained sounds or novel sounds within scenes; EEG was collected during testing. Participants trained with auditory scenes performed better overall than control participants. Both groups had lower reaction times to correct response change trials than same trials. Trained participants performed no better on trained sounds than novel sounds, but did perform better on trained sounds than control participants. Electrophysiologically, there were differences in ERP components based on the type of trial (change versus same auditory scene). For same trials, N1 and P2 amplitudes were significantly higher, and P3b amplitudes were significantly lower than change trials. Additionally, P2 showed a general decrease in amplitude as scene presentations neared the response. These data show that training reduces change deafness, and improvements are not limited to the sounds experienced during training.
Maternal depression and the timing of mother-child dialogue
Authors: McDaniel Valerie F. , Sowell Chloe M. , Boley Katherine A. , Janssen Janelle , Ispa Jean M. , Smith Nicholas A.
Published: December 2020

Early social interaction lays the foundation for developing language skills. Maternal depression may affect social interaction by disrupting the temporal structure of turn-taking. In this study, we examine the temporal properties of dialogue extracted from video recordings of semi-structured play between mothers and preschool children enrolled in the Early Head Start Research and Evaluation Program (n = 110). Our preliminary analyses examine how higher levels of maternal depression (on the CES-D scale) are related to the number and duration of utterances, the number of conversational turns, and the latency and variability of responses for both the mother and the child. The primary goal of the study is understanding how depression impacts bidirectional processes in mother-child interaction, and the quality of children's early language experience.
Non-modal sonorants in Hakha Lai
Authors: Berkson Kelly H. , Flego Stefon M.
Published: December 2020

Phonemic non-modal sonorants are both typologically rare and prone to diachronic loss crosslinguistically, but are robustly attested and diachronically stable in subgroups of Tibeto-Burman (TB) such as Kuki-Chin (KC). KC is a cluster of appr. 50 related languages spoken in Chin State in western Burma/Myanmar and by a large refugee community in Indiana. Chin languages generally contain rich phonetic inventories replete with 3-way laryngeal stop contrasts (e.g., /t th d/), lateral affricates (/tl, tlh/), and modal/non-modal sonorant pairs (most commonly /m m°, n n°, η η°, l l°, r r°/). Extant phonetic investigation ofnon-modal sonorants—in KC and beyond—is limited, and often focuses exclusively on the nasals, but recent data suggest highly variable phonetic instantiation across languages, speakers, and contexts that may involve true voicelessness, slack or breathy voicing, and pre- or post-aspiration. The current study presents acoustic analysis of the full suite of modal and non-modal sonorants in Hakha Chin. Data are from six native speakers (three female) now living in Indiana. A variety of temporal and spectral measures are reported in order to provide a more nuanced understanding of the degree and type of variation observed in production of these sounds.
The influence of inter-dialect contact on the Korean three-way laryngeal distinction: An acoustic comparison among Seoul, Gyeongsang, and bidialectal speakers
Authors: Kim Hyoju , Jongman Allard
Published: December 2020

This study investigates the acoustic correlates of the Korean three-way laryngeal stop distinction in Gyeongsang-based Seoul bidialectal speakers who were born in the Gyeongsang region but moved to Seoul to pursue higher-level education. The main purpose is to examine whether exposure to Seoul Korean affects bidialectal speakers' cue-weighting strategy to distinguish stops in production. Acoustic data were collected from 8 bidialectal, 5 Gyeongsang speakers (GK), and 11 Seoul speakers (SK). Bidialectal speakers produced stimuli in both Gyeongsang and Seoul dialect. A cue-weighting model of measured data reveals that VOT is less important to distinguish lenis from aspirated stops for SK and for bidialectal speakers' SK compared to GK and bidialectal speakers' GK. In addition, F0 is more important for the lenis-aspirated distinction for bidialectal speakers' SK and for SK compared to GK and bidialectal speakers' GK, showing that bidialectal speakers rely less on VOT and more on F0 to distinguish lenis from aspirated stops compared to GK. Bidialectal speakers' SK reveals that they rely more on VOT and less on F0 compared to SK. These results provide empirical support to previous studies (e.g., Lee & Jongman, 2019) suggesting that a series of changes in GK are due to inter-dialect contact.
Production of the vowels in the second person pronoun in Seoul Korean
Authors: Kim Jiseung , Lee Yoonjeong
Published: December 2020

The goal of the study is to investigate generational differences in the production of the vowels following /n/ in the second person singular pronouns /n⋀/ and /ni/ and the first person singular pronoun /ne/ in Seoul Korean. Due to the merger between the low front vowel /æ/ and the high-mid front vowel /e/, the semantic distinction between the first person pronoun and the second person pronoun was lost. Chae (1997) argued that it was the basis for the development of the new form of the second person pronoun /ni/ in Seoul Korean. However, no study as of yet has examined whether there are generational differences in the use of the new form with different particles and in different informational structure. The current study hypothesizes that there will be differences between younger and older speakers in the acoustic properties of the vowels in the second person pronoun that are modulated by the type of the postpositional particles as well as the informational structure of the utterances in Seoul Corpus (Yun et al., 2015).
Adding it all together: Temporally distributed minor correlates of a minor place contrast
Authors: Flego Stefon M. , Berkson Kelly H.
Published: December 2020

Laiholh (aka Hakha Chin, Hakha Lai) is a Kuki-Chin language that contrasts what has been described as lamino-dental and apico-alveolar articulations within coronal stops. As this type of minor place contrast is typologically uncommon and relatively understudied, the articulatory and acoustic properties distinguishing such pairs are not particularly well understood. It is unclear whether correlates reported for other languages hold cross-linguistically, or are language-specific. Our pilot investigation of this contrast in Laiholh revealed that very few acoustic differences between dentals and alveolars were stable across different vowel contexts and laryngeal settings. The current work expands our investigation by examining a larger data set and suite of acoustic parameters, including preceding and following formant transitions, closure duration, length of VOT, and spectral characteristics of aspiration. While acoustic differences tied to major place of articulation (labial versus coronal versus dorsal) are robust, those associated with the minor place difference within coronals are indeed minor. They have greater temporal distribution, however, being housed primarily in long-perseverating spectral information following stop release. We find constrained post-release spectral variation for apico-alveolar stops when compared with lamino-dental stops, suggesting that tongue body stabilization is associated with apical articulations, as reported for Wubuy (Best et al., 2014).
Random forest classification of Gitksan stops
Authors: Chow Una Y.
Published: December 2020

Gitksan, an endangered Tsimshianic language, has contrastive plain and ejective stops at five places of articulation (Rigsby, 1986). These lenis ejectives, which tend to be creaky-voiced, have been previously described as “implosives” (Hoard, 1978). This study asked which acoustic properties can distinguish ejective stops from voiced plain stops in Gitksan. Isolated Gitksan words (n = 540) containing initial prevocalic stops were audio-recorded from two male elder first-language talkers. A Praat script extracted voice onset time (VOT) and center of gravity (CoG) of the burst from the initial stop. VoiceSauce (Shue et al., 2011) extracted voice quality measurements (difference in amplitude between five harmonic pairs, cepstral peak prominence, and harmonic-to-noise ratios across four frequency bands) and three formant transitions from the onset of the post-stop vowel. A random forest model (Breiman, 2001) was fitted with these 15 measures to determine their relative importance in predicting the stop types and their places of articulation. The results suggest that VOT is the primary and voice quality is the secondary cue to stop type, while CoG is the primary and formant transition is the secondary cue to place of articulation in Gitksan. Intertalker variation in voicing and glottalization affects the ranking of these cues.
Speaking upside down: Manipulation of vowel formants with an inversion table
Authors: Aalto Daniel , Fenner Mike , Haarstad Meagan , Ostevik Amberley , Hodgetts Bill , Cummine Jacqueline
Published: December 2020

Posture affects the direction of gravitational forces on articulators. Since speakers seldom talk upside down, inverted posture offers an opportunity to observe the response of the neural control system to unfamiliar posture perturbations. Twenty native English speakers (16 women; 4 men) aged between 20 and 30 years gave written informed consent to participate in the study. They reported no history of hearing, balance, or speech problems. The participants were secured on an inversion table which was rotated and fixed to three positions: upright, supine, and upside down. The order of the postures was randomized. A headphone mounted microphone recorded series of ten repetitions of three words with target vowels /i,u,a/ embedded in a carrier word /hVd/ in each posture. Formants were extracted from the middle of the vowel using Praat. Results and discussion: Every participant's productions were impacted systematically by posture with greater acoustical effects observed for the unfamiliar posture. Based on mixed effects models, the F1 and F2 responses between participants aligned for /i/ in upside down condition compared to upright posture. The data suggests that unfamiliar (upside down) postural perturbation leads to greater deviation from its acoustic target than a familiar (supine) postural perturbation.
Acoustic differences between Salvadoran and Chilean Spanish [s]
Authors: Bolyanatz Brown Mariska
Published: December 2020

This paper examines the acoustic properties of [s] in Salvadoran and Chilean Spanish across multiple prosodic positions. Speakers are 36 working-class Chileans and Salvadorans balanced for dialect and gender who participated in an identical narration task in their respective home countries in 2015. Comparisons of fricative duration, relative intensity, the first four spectral moments, and percent voicelessness reveal multiple significant differences across dialects. Salvadoran Spanish [s] showed lower relative intensity, lower spectral Center of Gravity, higher variance, and more positive skewness across prosodic positions (word initial, word final, word-medial onset, and word-medial coda). Taken together, these results suggest previously unattested dialectal differences in degree of constriction and place of articulation of Spanish [s].
Exploring invariant durational structure for voiceless and voiced stop quantity distinction in Kagoshima Japanese
Authors: Koya Shonosuke , Ishibashi Shoji , Takeyasu Hajime
Published: December 2020

Hirata and Whiton [J. Acoust. Soc. Am. 118, 1647–1660 (2005)] found that the durational ratio of stop closure to word (C/W ratio) is an invariant parameter for disyllabic words that differentiates voiceless single and geminate stops in Standard Japanese, a mora-timing language. The present study examines whether C/W ratio is an invariant parameter for voiced as well as voiceless stop quantity distinction in disyllabic words in Kagoshima Japanese, a syllable-timed dialect in Japanese. A production experiment was conducted in which three native speakers of Kagoshima Japanese (ranging from 54 to 86 in age) uttered in carrier phrases 27 disyllabic words, including 4 minimal pairs for voiceless stop quantity (e.g., popo versus poppo) and 4 minimal pairs for voiced stop quantity (e.g., kogo versus koggo). The rest of them were filler words. C/W ratio and five other possible parameters were calculated based on duration of each segment. Results of statistical analysis [classification accuracy, Akaike's information criterion (AIC), and Bayesian information criterion (BIC)] indicated that C/W ratio most accurately distinguishes single and geminate stops in Kagoshima Japanese as well as in Standard Japanese. [Work supported by Grant-in-Aid for Scientific Research, JSPS.]
Modelling of sound propagation in the ocean using the matrix propagator
Authors: Makarov Denis
Published: December 2020

The problem of sound propagation in an oceanic waveguide is considered. Attention is concentrated on properties of a wavefield propagator that governs transformation of an arbitrary wavefield in course of propagation. Using the basis of normal modes, we can represent the propagator in the matrix form. If horizontal inhomogeneity of a waveguide is weak, the propagator can be calculated by means of the first-order perturbation theory. In the case of random inhomogeneity, the apparatus of random matrix theory can be exploited. We demonstrate methods of propagator construction for realistic models of waveguides, including waveguides with adiabatic inhomogeneities and shallow-sea waveguides. A scheme of experimental measurement of a propagator in a shallow-sea waveguide is proposed.
Modeling of signals scattered by turbulence on a sensor array using the matrix gamma distribution
Authors: Ostashev Vladimir , Wilson D. Keith , Kamrath Matthew J. , Pettit Chris L.
Published: December 2020

The complex Wishart distribution provides a joint probability density for acoustic signals at a sensor array, in the regime of fully saturated scattering. In this presentation, the marginal distributions of the complex Wishart distribution are calculated using the characteristic function. A generalization of the complex Wishart distribution, namely the matrix gamma distribution, is proposed as a means for modeling the full saturation and unsaturated regimes. Asymptotic behavior of the matrix gamma distribution, and the consistency of its marginal distributions with predictions from the theory of wave propagation in random media, are studied. The predicted marginal distributions are compared to data from a comprehensive outdoor sound propagation experiment carried out in September 2018 at the National Wind Technology Center, Boulder, Colorado. In the experiment, microphones were attached to horizontal booms mounted at three heights on a 135-m meteorological tower, while a loudspeaker was positioned at the base of the tower or at a distance of 56 m from it.