bluuebunny/crossref_metadata_2025 huggingface dataset:
Tracking the spatiotemporal variability of the oxic-anoxic interface in the Baltic Sea with broadband acoustics
Authors: Weidner Elizabeth F. , Stranne Christian , Sundberg Jonas H.
Published: November 2019

The Baltic Sea is characterized by strong stratification, high nutrient loads from anthropogenic sources, and poor circulation. Consequently, an anoxic zone exists in the bottom waters of large regions of the Baltic Proper. Anoxic conditions have led to water column habitat loss, elimination of benthic fauna, disruption of food webs, and altered biogeochemical nutrient cycling. The onset of anoxic zone is concomitant to the depth of the halocline, which separates the fresher, oxygenated surface waters from the deeper anoxic waters. As a result, the interface of oxic-anoxic waters corresponds to a strong impedance contrast brought about primarily by a sharp gradient in salinity. The acoustic reflection from this impedance contrast was tracked utilizing a broadband (45-90 kHz) split-beam echo sounder in the western Baltic Proper. The broadband acoustic dataset provides the means to remotely observe the spatiotemporal variations of the oxic-anoxic interface. In this study, we capitalize on this to discern the mechanisms influencing the vertical distribution of oxygen in the water column and its effects on fine-scale fish distribution. The methodological development of high resolution anoxic layer tracking with the concurrent study of oceanographic and biological features using broadband acoustics opens up a new level of understanding of the fine-scale ecosystem interactions in the Baltic Sea.
Whole-cell patch clamp for monitoring low--energy focused ultrasound (LEFUS)-induced electrical activity in individual neurons
Authors: Suarez Castellanos Ivan M. , Perier Magali , Vion-Bailly Jérémy , Birer Alain , N'Djin Apoutou
Published: November 2019

The objective of this project was to integrate a LEFUS-system to a patch-clamp platform for exploration of LEFUS-modulated and/or -stimulated electrophysiological responses from individual cultured neurons. Mouse primary neurons and human neural progenitor cells were cultured and plated onto 35-mm diameter Petri dishes. A whole-cell patch-clamp setup in current-clamp mode was used to record electrophysiological activity generated by the neurons. The LEFUS system consisted of a 2.2-MHz planar transducer (diameter: 10-mm), administering 0.5–10 ms pulses at pressures of 6–50 kPa. Neuromodulation studies consisted in measuring changes in the activation threshold to electrical stimulation (current density required to trigger an action potential: AP) in LEFUS-treated neurons. Neurostimulation experiments consisted in measuring electrophysiological responses to LEFUS exposures in the form of triggered APs or electrical discharges from the patched neuron. Neuromodulation results showed that the activation threshold required for triggering APs could be either elevated or lowered by approximately 25% following LEFUS treatment. In neurostimulation experiments, LEFUS pressures of 25 kPa and pulse durations of 10 ms were sufficient for either disturbing the membrane potential of the cell and, occasionally, depolarizing the neuron by approximately 70 mV. [This project was supported by the French National Research Agency (ANR-16-TERC-0017), LabEx DevWeCan, and Focused Ultrasound Foundation (Centers of Excellence).]
Acoustically stressing biofilms formed by Pseudomonas aeruginosa
Authors: Bharatula Lakshmi Deepika , Rice Scott , Marsili Enrico , Kwan James J.
Published: November 2019

Bacterial biofilms, the complex and dynamic assemblages of bacterial cells, have shown increased tolerance to antimicrobials compared to their planktonic counterparts. Altered metabolism and micro-environments, in addition to the self-generated extracellular polymeric substances (EPS), collectively help to protect the bacteria from the effect of antimicrobials, thereby increasing the necessity for novel treatment methods that are effective against biofilms. To address this, we have investigated the effect of high intensity focused ultrasound (HIFU) in killing or dispersing biofilms. HIFU reduces the total biofilm biomass without significant cell killing. To investigate the molecular mechanism of action of HIFU, we quantified the intracellular concentrations of cyclic di-GMP, which regulates the switch between biofilm and planktonic life-styles. Biofilms grown on polymeric sheets were exposed to HIFU at 0.5 MHz frequency and the c di-GMP concentration was characterized using confocal microscopy. Changes in the c di-GMP activity localized at the acoustic focus were observed as the biomass decreased. The mechanisms promoting these changes were further investigated by examining the shape of individual bacterial colony grown on agar plates. The observed effects were compared to sham (negative control) and c di-GMP overproducing mutant (positive control).
Temperature-dependent dispersion characteristics of Rayleigh waves in soft tissues
Authors: Han Tae-Woo , Lee Hunki , Im Seonghun , Ohm Won-Suk , Kim Won-Joong
Published: November 2019

The frequency-dependent shear modulus of a soft tissue gives rise to dispersion of (otherwise nondispersive) Rayleigh waves, the measurement of which can offer a means to study various surface properties of the tissue. Among the factors that influence the shear modulus (hence Rayleigh-wave dispersion) of a tissue is temperature, where the shear modulus often decreases with increasing temperature. In this talk, we discuss the temperature dependence of dispersion characteristics of Rayleigh waves propagating along the surface of soft tissues. Rayleigh-wave spectroscopy was performed at temperatures ranging from 25 to 40 °C using soft tissue phantoms that closely mimicked the physical properties human dermis. It was found that Rayleigh-wave dispersion exhibits high sensitivity to change in temperature, which could be used in real-time, noninvasive monitoring of skin temperature.
Evaluating robustness of local phase velocity imaging in elastic and viscoelastic phantoms
Authors: Wood Benjamin , Kijanka Piotr , Urban Matthew W.
Published: November 2019

Local Phase Velocity Imaging (LPVI) is a novel method of shear wave elastography (SWE) analysis, which provides phase velocity images at multiple frequencies. The primary components of this method include using two acoustic radiation force (ARF) pushes near the edges of the field-of-view. Fourier analysis of the spatiotemporal data is conducted to obtain maps of the phase velocity at multiple frequencies. A robustness study was conducted to evaluate the effectiveness of LPVI in elastic and viscoelastic phantoms with different mechanical properties, ARF focal depths and F-numbers, and shear wave frequencies using a linear array transducer. The results showed effective phase velocity reconstructions for most scanning parameters in the phantoms evaluated. We evaluated mean and standard deviations of phase velocities in the different phantoms for regions-of-interest defined in the images. Issues were seen with shear wave signal being distorted from the incident push when using low F-numbers as well as issues with attenuating shear waves with higher F-numbers and deeper focal depths. Future directions of this work will be to evaluate the robustness of LPVI in inclusion phantoms as well as testing on a curved array transducer.
Model-data comparison of the parabolic equation approximation for long-range propagation, time spreading, and channel bandwidth estimation
Authors: Hines Paul C. , Deveau Terry , Kusel Elizabeth , Barclay David R. , Nams Dainis , Coffin Matt
Published: November 2019

Underwater communications and sonar measurements in the Arctic are challenging due to the remoteness and the vast area to be covered. Acoustic modeling is critical to support measurements since it can help inform experimental plans and extend the usefulness of results to other areas. Low-frequency systems are generally required to deal with the vast ranges being covered and to mitigate the high-frequency signal loss caused by under-ice roughness. The Parabolic Equation Approximation (PE) is well suited to the low-frequency band but properly accounting for the rough, elastic, ice layer is challenging. A recent project has integrated a rough, elastic, ice layer into a long-range, time-domain PE model to provide complementary modeling support for a newly developed low-frequency Arctic sonar system. This presentation will review propagation measurements and the supporting PE modelling from a deep water experiment off the Scotian Shelf at frequencies from 16 to 250 Hz and ranges up to 700 km, prior to deployment in the Arctic.
Application of elastic parabolic equation solutions to acoustic reverberation in ice-covered underwater environments
Authors: Frank Scott D. , Ivakin Anatoliy N.
Published: November 2019

Parabolic equation solutions can be obtained for underwater acoustic environments where elastic boundaries affect the acoustic propagation. One example of this situation is in the Arctic where a (potentially rough) ice layer is on top of the water column. The parabolic equation method shown here rigorously applies the zero-traction and fluid-elastic interface boundary conditions to obtain full field Green’s function estimates near the ice-water interface. This solution is crucial for calculation of recently derived reverberation estimates that require both horizontal and vertical derivatives of the complex acoustic field. Monostatic reverberation estimates for a rough under-ice interface are calculated for an upward refracting water sound speed profile and an elastic ocean bottom with a nearly fluid mud layer. These calculations could be used, for example, to estimate areal distribution of the ice layer roughness from azimuth-time dependence of acoustic reverberation measured in Arctic environments. Performance of the Padé rational function approach in the presence of thin ice cover and low shear speed ocean bottom layers will be addressed.
Using acoustics to prepare undergraduate physics majors for the fundamentals of quantum physics
Authors: Hoffman Kurt
Published: November 2019

As part of curricular changes in our Physics curriculum, I developed an acoustics lecture course as a bridge between General Physics and our modern physics course. The goals of this course were to provide students with new mathematical tools (solving the wave equation, using complex numbers, boundary conditions) while also making physical connections between the mathematics and a system they could work with in a classroom. My aim was to prepare them for the mathematics to solve quantum problems so that they could spend more time wrestling with abstract quantum concepts. I used a textbook for vibrations and waves as a basis for the course and supplemented the text with acoustics specific content. I will present an outline of my approach and feedback from students regarding the utility of using acoustics as a primer for the more abstract content encountered in a Modern Physics course. Surveys and student reflections solicited after completing both courses will be discussed. My presentation will focus on whether the benefits of using acoustics to help students prepare for quantum physics warrants inclusion in the standard curriculum.
Visualization and acoustic-triggered conditional sampling analysis of acoustic phenomena with screech-tone of an over-expanded supersonic jet
Authors: Takemura Miho , Okamoto Koji , Teramoto Susumu
Published: November 2019

In the liftoff of launch vehicles and supersonic aircrafts, jet noise is required to be reduced because it causes various problems. To reduce the influence of jet noise, it is significant to clarify the source location and the direction of propagation as well as the spectrum of each acoustic phenomenon. For this purpose, the authors have proposed the acoustic-triggered conditional sampling analysis to obtain acoustic information from high-speed schlieren movies. In the authors’ previous studies, this method was applied to correctly and under expanded jets, and the broadband phenomena were clarified, such as Mach wave radiation and shock associated noise. In this study, this method was applied to an over-expanded jet, in which screech tone is observed in addition to the broadband acoustic phenomena. First, it was found that the broadband phenomena and screech tone could be observed separately by this method with choosing the microphone location for trigger detection. Then, two screech tone noises of different frequencies are observed, and it was clarified that they are propagating to different directions from different source locations. Also, the acoustic phenomenon generated by impingement of the same over-expanded jet on an inclined flat plate will be discussed.
Passive jet noise reduction using contoured inserts
Authors: Murray Nathan E.
Published: November 2019

Successful supersonic jet noise reduction requires an approach that simultaneously (1) breaks up coherent structures in the jet shear layer turbulence, (2) reduces convection velocity of the acoustic sources, and (3) weakens the shock structure in the plume. If any one of these is done in isolation the result is typically a shift in frequency content and not an overall reduction in source amplitude. Using a set of contoured inserts placed within the expansion section of the nozzle allows all three of these design goals to be addressed. The contour weakens the shock structure while simultaneously generating strong streamwise vorticity the enhances mixing in the jet shear layer. Assuming that future high-performance aircraft would possess a variable area ratio nozzle with independent exit and throat area controls, multi-objective design optimization has yielded a design that maximizes noise reduction with minimal thrust penalty in a variable area ratio framework. Model-scale acoustic data are presented to demonstrate the efficacy of the design.
Connecting high-power jet noise characteristics with human annoyance: Physical characterization
Authors: Vaughn Aaron , Gee Kent L. , Downing Micah , James Michael M. , Calton Matt , Wall Alan T.
Published: November 2019

Physical characterization of annoying components of jet noise will aid in future noise mitigation efforts. Crackle perception is a significant contributor to annoyance produced by supersonic jet noise and is related to the reception of acoustic shocks. The skewness of the pressure time derivative, or derivative skewness, is sensitive to the presence of acoustic shocks and has been shown through listening studies to be indicative of crackle perception. Extensive measurements of a tied-down high-performance military aircraft allow for the examination of spatial variation and source characterization of events related to crackle perception in the field. A variety of factors contribute to the derivative skewness in the field, such as source-receiver distance, apparent source origin, or whether a microphone is placed on or elevated off the ground. Spatially, the derivative skewness often peaks in the maximum radiation region, however, deviations exist at lower engine conditions with sudden increases in derivative skewness in the aft region. An event-based beamforming method is implemented to examine the source region, with resulting directivities lending insight into far-field crackle perception. Characterization of crackle perception using derivative skewness as an indicator will increase understanding of mechanisms contributing to jet noise annoyance. [Work Supported by AF SBIR Program.]
Comparative analysis of three falcon 9 launches
Authors: Mathews Logan T. , Rasband Reese D. , Novakovich Daniel J. , Irarrazabal Francisco J. , Vaughn Aaron , Nelson Pauline , Gee Kent L.
Published: November 2019

This study investigates the noise from three separate Falcon 9 vehicle launches from Vandenberg Air Force Base, as measured within the community of Lompoc, CA. Although one focus of these tests was to test a variety of acoustical and weather instrumentation systems and configurations, the launches also provides an opportunity to study and compare the launch noise measured under potentially different weather conditions. An analysis of the levels and spectra is shown for different time periods. The prevalence of acoustic shocks is examined in the context of environmental conditions and recording locations.
Reducing noise from twin supersonic jets using very-low-frequency control
Authors: Murthy Sandeep R. , Bodony Daniel J
Published: November 2019

The intense jet noise radiated by closely spaced, twin supersonic hot jets leads to sound-induced structural vibration, fatigue and personnel related operational difficulties. Experimental, theoretical, and computational investigations into the physics and control of jet noise have identified several important sound sources, including wavepackets, screech, Mach wave radiation, and broadband shock associated noise (BBSAN). Reducing the loudest sources of jet noise, without sacrificing propulsive performance, has relied on intuition, parametric survey, or optimal control techniques. With the aim of developing a more general and robust method of jet noise reduction (JNR), we present a physics-based approach that leverages very-low-frequency jet dynamics in order to achieve JNR whilst preserving propulsive performance. Our approach formulates the control problem using the very-low-frequency global modes of the compressible Navier-Stokes operator linearized about the jet mean flow to disrupt the nonmodal transient growth processes. The presentation will showcase uncontrolled and controlled single and twin supersonic hot jets issuing from biconical nozzles, with conditions and geometries motivated by tactical Naval aircraft. The predictions utilize fully resolved numerical simulations whose data inform the control development and which evaluate its performance on the jet exhaust and on its radiated noise.
Controlling underwater sound propagation using 3-D-printed phononic crystals
Authors: Allam Ahmed , Sabra Karim G. , Erturk Alper
Published: November 2019

Metamaterial concepts are revolutionizing the way we tackle acoustic wave propagation control. For aqueous media, the realization of metamaterial and phononic crystal concepts using impedance contrast has been mainly limited to using heavy metallic rods which are often bulky and complicated to fabricate to achieve the required geometry. In this work, we introduce a novel and simple technique that utilizes 3-D printing using standard materials such as PLA polymers to construct a phononic crystal which can be engineered to manipulate underwater waves over a broad frequency range. The proposed design uses an air and polymer matrix to tailor the effective spatial refractive index distribution of the material in order to achieve sufficient refraction. Based on this approach, a 3-D Luneburg gradient index lens prototype was 3-D printed, which can focus underwater acoustic waves with minimal reflection. The cube-shaped lens was fabricated using a common desktop printer and was experimentally characterized. Finite-element modeling of the lens was also performed for band structure analysis and wave field simulations. The results show good agreement between the numerical predictions and the experimental measurements. The developed lens was then used to enhance the performance of an acoustic wireless power transfer system, yielding significant improvement of the power output on the receiver end. The proposed concept and lens design can also be used in other applications such as underwater sensing.
Simulating transmission through anisotropic pentamode materials submerged in water
Authors: Kelsten Matthew , Norris Andrew
Published: November 2019

Interest has increased in recent years on the potential for underwater metallic metamaterials, which can be linked to the advancements in metal 3-D printing. One metamaterial of particular interest is an underwater anisotropic pentamode, i.e., a structure designed to support a single longitudinal wave for a broad-range of frequencies whose speed will change depending on its orientation relative to the incident acoustic wave. In an attempt to close the gap between experiment and theory, COMSOL simulations have been developed modeling the transmission and reflection of a normal plane wave incident on an anisotropic pentamode metamaterial consisting of tetrahedral unit cells. The utilization of the Floquet periodic boundary conditions allows for the replication of a semi-infinite medium response composed of repeating unit cells while only using a finite CAD drawing. Meshing techniques and geometric work-arounds are discussed in an attempt to achieve a cost-effective computation absent of numerical instabilities for a broad range of frequencies. Results show dynamic stress concentration is focused mainly at the joints of the unit cells. Plates designed to separate the fluid medium from the internal structure are shown to exhibit higher modes of vibrations, however contribute little to the far field due to energy flux conservation.
Duplex theory and human localization of 1000-Hz tones
Authors: Hartmann William M. , Rakerd Brad , Shore Aimee , Kassis Jordan
Published: November 2019

The roles of interaural time difference (ITD) and interaural level difference(ILD) were studied in free-field source localization experiments with 1000-Hzsine tones. Experiments combined real-source trials with virtual-source trialsusing two-channel transaural synthesis based on real-time measurements in the ear canals. Critical virtual trials used fixed, azimuth-independent ILDmagnitudes of 6 or 12 dB. The ILD signs were either consistent with the ITD or opposing. Experiments found that the main role of an opposing ILD was to act as a binary switch, turning on slipped-cycle localization, with some additional sensitivity to ILD magnitude. Therefore, it proved possible to use the localization results from consistent-ILD trials to predict opposing-ILD localization decisions as detailed functions of source azimuth. These results are consistent with the revised duplex theory as observed at lower frequencies[J. Acoust. Soc. Am. 139, 968–985 (2016)], but the effect is more dramatic at 1000 Hz because fewer source azimuths lie in the transition region where slipped-cycle ITD values are large. Parallel headphone experiments with the same listeners showed a similar switching effect in lateralization but also showed greater variability and sensitivity to the ILD itself. [Work supported by the AFOSR.]
Effect of amplitude fluctuations on the loudness of low-frequency sounds
Authors: Jurado Carlos , Gordillo Darío , Moore Brian C.
Published: November 2019

The loudness of two-tone complexes (TTCs) with center frequencies (fc) of 40, 63, 80, and 1000 Hz was matched with that of unmodulated tones (UTs). Frequency differences between the TTC components, corresponding to beat frequencies, fb, were 1, 2, 5, and 12 Hz. To compensate for the steep decline in hearing sensitivity below 100 Hz, prior to the loudness match, subjects adjusted the relative levels (ΔL) of the TTC components to give maximum beat perception. Twenty-four normal-hearing subjects were tested. The values of ΔL giving best beats were well predicted from the transfer function of the middle ear and the estimated shapes of the auditory filters, assuming that the auditory filter whose output dominated the beat percept was centered somewhat above fc. At the same root-mean-square level and independent of fc, TTCs were perceived as louder than UTs for fb ≤ 2 Hz, had roughly equal loudness to UTs for fb = 5 Hz, and were less loud than UTs for fb = 12 Hz. The similar pattern observed across fc suggests that the dependence of loudness on amplitude-fluctuation rate is determined by processes occurring at higher stages of the auditory system than the cochlea.
Cognitive load distorts the perception of core acoustic dimensions of speech
Authors: Chiu Faith , Rakusen Lyndon , Mattys Sven
Published: November 2019

Dual-tasking negatively impacts on speech perception by raising cognitive load. Previous research has shown that cognitive load increases reliance on lexical knowledge and decreases reliance on phonetic detail. Less is known about the effect of cognitive load on the perception of acoustic dimensions below the phonetic level. This study tested the effect of cognitive load on the ability to discriminate differences in duration, intensity, and fundamental frequency of a synthesized vowel. A psychophysical adaptive procedure was used to obtain just noticeable differences (JNDs) on each dimension under load and no load. Load was imposed via N-back tasks at two levels of difficulty (1-back, 2-back) and under two types of load (images, written nonwords). Compared to a control condition with no cognitive load, all N-back conditions increased JNDs across the three dimensions. JNDs were also higher under 2-back than 1-back load. Nonword load was marginally more detrimental than image load for intensity and fundamental frequency discrimination. Overall, the decreased auditory acuity demonstrates that the effect of cognitive load on the listening experience can be traced to distortions in the perception of core auditory dimensions.
Effects of pitch height and contour on duration perception
Authors: Grabowski Emily J.
Published: November 2019

Generally, low tones are produced as longer than high tones and rising as longer than falling (Gandour, 1977). Work in perception has revealed the inverse pattern, which has been described as a reaction to production differences (Yu, 2006). However, while the perception results have been observed reliably cross-linguistically, production patterns appear to have significant variation, which calls into question a direct link between production and perception and motivates more research into the nuances of this relationship. This study investigates the perception of duration in an expanded set of pitch contours via a two-alternative forced-choice task. Subjects were asked to choose which of two same-duration synthesized speech sounded longer, where stimuli varied in pitch height and contour. The results indicate that pitch height has the strongest effect on perceived duration, followed by contour-related effects, which contrasts with predictions based on to Gandour’s analysis of the production pattern. Additionally, this study reveals the complexity of the perception pattern beyond the main effects commonly reported in the literature.
Detection of nasals as a function of duration
Authors: Huang Ting
Published: November 2019

Previous studies have shown distributional restrictions on nasal stops. Specifically, in many languages nasal stops are followed only by a nasal vowel, which is also usually comparatively longer to contrast with the vocalic context adjacent to oral stops. This was observed as a phonological constraint in Taiwanese (Southern Min), but not in French. This study tests the discriminability of Taiwanese and French listeners on plain and nasal stops. The speech stimuli were cross spliced nasal versus oral stops and oral versus nasal vowels: CV, NV, CṼ, NṼ. The vowel duration was also manipulated to see if the perceived nasality will be enhanced when the vowels are longer, and further affect the intelligibility for the consonants before them. Preliminary results indicated that the Taiwanese listeners predicted wrong consonantal categories when the nasality of the following vowel is not agree with the preceding consonant. French listeners showed no such effect. The durational effect shows the opposite: Taiwanese listeners perceived the same stop category regardless of the duration of the following vowel, whereas French listeners are biased toward the nasal category when the following vowel is longer.
Effects of variability and internal structure on malleability of phonetic categories: A case of [i] versus [u]
Authors: Kataoka Reiko , Koo Hahn
Published: November 2019

Recent studies on retuning of phonetic categories by lexically guided perceptual learning suggest an inverse relationship between inherent acoustic variability and malleability of phonetic categories—the greater the variability, the smaller the retuning effect. However, it remains to be investigated what perceptual processing mechanisms are responsible for the observed relationship. Extending our previous study (Kataoka and Koo, 2017) that compared the degree of malleability between [u] (more variable) and [i] (less variable), we not only compared the size of retuning effect between the two vowels but also examined how listeners judge category goodness of synthesized stimuli from a [i]-[u] continuum. Our subjects (1) showed signs of category retuning for [i] but not for [u] and (2) judged goodness of stimuli in a more gradient manner and took longer to do so when asked to judge with reference to [u] than [i]. The results suggest that the two vowels differ in terms of their acoustic variability as well as their internal structure and that relative difficulty in resolving input speech signal in reference to a category such as [u] might be one reason the category is less malleable than a less variable category such as [i].
Gender differences in voice onset time perception
Authors: Kim Seung Kyung
Published: November 2019

It has been known for a while that a gender difference in voice onset time (VOT) production exists such that males typically produce shorter VOTs than females (Swarts, 1992; Robb et al., 2005). However, potential gender differences in VOT perception have not been systematically investigated. This study addresses this question and asks if male and female listeners of English exhibit a different crossover point in a VOT continuum between a voiceless and voiced sound. 11-step VOT continua between /t/ and /d/ (VOT ranges from 70 ms to 5 ms) were created and a set of identification tasks were performed. Results show female listeners switch from a /t/-percept to a /d/-percept at an earlier VOT step (i.e., with a longer VOT) than male listeners do. That is, when female listeners start to categorize a token as a /d/-sound, male listeners still categorize the same token as a /t/-sound. This difference in the perceptual pattern between males and females mirrors their difference in production. VOTs for /t/ are typically shorter for male than female speakers, and male listeners categorize shorter VOT tokens as /t/ more often than female listeners do. This finding highlights the role of social factors like gender in the production-perception link.
The influence of word size and tonal sequence probability on Mandarin well-formedness judgments
Authors: LaCross Amy , Sandoval Jordan , Liss Julie
Published: November 2019

Work in tonal languages has demonstrated that distributional information is important in speech processing. Probability of syllable + tone combinations play a role in speech processing in Mandarin (Wiener and Ito, 2015, 2016; Wiener and Turnbull, 2013), and transitional probabilities of tone-bearing vowels are important in Cantonese segmentation (Gomez et al., 2018). However, the importance of variables like word size and tonal sequence probability is less well understood. Further, while disyllabic words are by far the most common word size in Mandarin (Duanmu, 2007), research into word-likeness has only explored listeners’ judgments of single-syllable prompts (Kirby and Yu, 2007; Myers and Chen, 2017; Gong and Zhang, 2019). The role of word length and distributional probabilities of tonal sequences within multi-syllabic words need to be examined. We conducted a phonological well-formedness task varying stimuli by number of syllables and tonal sequence probability, hypothesizing that listeners would rate two-syllable words and words with higher probability tonal sequences as better formed than low probability word forms. The experiment is ongoing, but preliminary findings fail to indicate a significant effect of either word size or tonal sequence probability on well-formedness ratings. Current analyses explore the potential influence of lexical neighborhood on listeners’ judgments.
Contextual effects on the distinction of Japanese length contrasts in reverberation
Authors: Osawa Eri , Arai Takayuki
Published: November 2019

Temporal structure in a word is crucial for understanding speech. In the distinction between Japanese singleton and geminate stops, listeners tended to perceive a consonant as geminate when the preceding vowel was longer [Ofuka et al., J. Phonetics Soc. Japan 9(2), 59–65 (2005)]. At the same time, listeners may not be able to use the contextual information in reverberation since the boundaries between each speech sound may become blurred by reverberation elongating and overlapping the sounds. The current study investigated whether the category boundary between singleton and geminate might change depending on duration of the preceding vowel in reverberation. Participants made a choice between singleton and geminate consonants embedded in an /a a/ context. The duration of the preceding vowel was changed. The experiments were conducted in a reverberant (RT = 2.6 s) and non-reverberant (RT = 0.1 s) condition. The results showed a significant shift in category boundary which indicated that listeners gave more “geminate” responses when the preceding vowel was longer, especially in the reverberant condition. The preceding vowel lengthened by reverberation caused listeners to choose “geminate.” Listeners might be more sensitive to the length of the adjacent phonemes for assessing the degree of reverberation.
Phonetic cues influence judgment of syntax
Authors: Remirez Emily
Published: November 2019

This speech perception experiment provides evidence of interaction between phonetic and syntactic cues associated with socio-/ethnolects. These phonetic and syntactic (socio)linguistic cues were crossed in stimuli recorded by speakers of African American English (AAE), Southern Standard British English (BrE), and General American English (GAE). Thus, some of the sentences listeners heard contain 'matching' cues—for example, a have raising question with BrE phonetic features—while the others contain “mismatching” cues much less likely to have been experienced together by listeners. Listeners (n = 30) rated the spoken utterances' acceptability on a scale of 1 to 5; response time was recorded. The mixed-effects linear regression fitted to the Z-transformed data shows BrE and AAE constructions are more acceptable when the phonetic cues match. The effect is most robust for the BrE accent; compared to estimates for the GAE accent ( β = 0:9538, p < 0.001), those for the BrE accent are overall lower (β = −0.106, p = 0.048). The penalty is effectively counteracted, however, when the BrE voice is producing the associated syntactic construction (β = 0:181, p = 0:017). Response time data also suggests stimuli with matching cues are processed faster (t = -2:3586, p = 0:01856).To my knowledge, this is the first experimental evidence of an effect of accent on syntactic acceptability.
Processing prosodically driven variations in lexical access
Authors: Shin Seulgi , Tremblay Annie
Published: November 2019

This study investigates whether prosodically driven variants constrain lexical access by focusing on the processing of prosodically licit and illicit Korean lenis plosives and nasals. Lenis plosives are aspirated phrase-initially but voiced phrase-medially; nasals undergo nasal weakening (“denasalization”) phrase-initially but not phrase-medially. Importantly, denasalized nasals share acoustic similarities with voiced lenis plosives. Seoul Korean listeners completed four cross-modal priming experiments where primes in phrase-initial sentential position were related (experimental) (e.g., /tapal/ “bundle”) or unrelated (control) (e.g., /tʃodɛ/ “invitation”) to visual targets (e.g., 다발/tapal/). The target began with a lenis plosive (Exps. 1 and 2) or nasal (Exps. 3 and 4). The experimental prime began with a prosodically licit (Exp. 1: aspirated lenis, Exp. 3: denasalized nasal) or illicit (Exp. 2: voiced lenis, Exp. 4: nasalized nasal) variant. The results showed that experimental primes with a prosodically licit variant (Exps. 1 and 3) facilitated word recognition. For prosodically illicit variants, experimental primes with a nasalized nasal (Exp. 4) facilitated word recognition but experimental primes with a voiced plosive did not (Exp. 2). The facilitation in Exp. 4 suggests that prosodically driven variants do not constrain lexical access; the lack of facilitation in Exp. 2 is attributed to lexical competition from nasal-initial words.
A perceptual perspective on Cantonese tonal mergers-in-progress using lexical categorization
Authors: Soo Rachel , Babel Molly E.
Published: November 2019

Cantonese is generally described as having a six tone system, composed of 3 level, 2 rising, and 1 falling tones. Researchers have observed that several of these tones have been merging; for example, Tone (T) 2 and T5 [Bauer et al., LVC 15(2), 211–225 (2003)], T3 and T6, and T4 and T6 [Mok et al., LVC 25(3), 341–370 (2013)]. In perception, discrimination-based paradigms show that Cantonese speakers are slower and poorer at discriminating said merging tone pairs [Mok et al., LVC 25(3), 341–370 (2013); Soo and Monahan, BLS 43(2), 47–54 (2017)]. In this study, we examine these mergers in terms of word identification to develop an understanding of the nature of the mergers. Homeland and heritage Cantonese listeners categorize minimal pairs on an 11-step continuum for T2–T5, T3–T6, and T4–T6. Pictures are used as the lexical endpoints, as many participants in the sample do not read characters. Analysis of the categorization functions provide further empirical data on whether listeners are perceptually merged in a way that affects lexical identification. Additionally, these data will shed light on the taxonomy of the mergers to determine whether these are mergers by expansion, approximation, or transfer.
Influences of preceding speech rate and prosodic position on listeners’ perception of durational cues
Authors: Steffman Jeremy
Published: November 2019

Research suggests that listeners incorporate expectations about the temporal organization of prosodic structure in their perception of durational cues. Steffman (2019, JASA) tested sensitivity to phrase-final lengthening: listeners categorized a “coat”∼“code” vowel duration continuum (increased duration cues voicing) in a carrier phrase. The target was either phrase-medial or phrase-final. Listeners required longer vowel durations for a “code” response when the target was phrase-final, suggesting an expectation of lengthening in final position influenced perception of duration. The present study tests how listeners are sensitive to preceding speech rate changes in tandem with prosodic/positional effects. Using the same stimuli as Steffman (2019), preceding speech rate was manipulated orthogonally to position (2 × 2): a target was phrase-final or medial, preceded by either slow or fast precursor speech. Results show independent influences of rate and position on categorization, which are differently localized. Positional effects are concentrated at longer vowel durations which align with typical durations for phrase-final vowels. Rate effects localize in the middle region of the continuum. These results offer some support for the idea the prosodic effects in perception depend on durational patterns in the language, and extend Steffman (2019) to show that listeners integrate both speech rate and prosodic information in perception.
Parallel computing using Python-based software for a high-frequency ultrasound system
Authors: Villalba Alejandro I. , Landry Thomas , Brown Jeremy
Published: November 2019

Python has become a widely used programming language for scientific research. However, python’s computational speed is limited when compared with other languages. This work presents an upgraded open-source imaging software based on python, which is capable of acquiring, processing, and displaying B-mode images in real-time for a high-frequency phased array imaging system. Ultrasound systems, considered to be real-time, display images at a frame rate of >20 Hz. This software uses 3 central processing units (CPUs) for parallel processing. In addition, Graphics Processing Unit (GPU) parallel computing is achieved by employing OpenCL commands and executing them directly on the GPU. New features, such as frame weighted averaging, color flow overlay and image enhancement, were also implemented. Parallel computing increased the displayed frame rate in general B-mode from 20 Hz to 35 Hz. B-mode + color flow overlay was increased from 15 Hz to 29 Hz and enhanced B-mode (applying edge detection, blur, and FFT filtering) was increased from 14 Hz to 28 Hz. Finally, enhanced B-mode + color flow overlay frame rate was increased from 8 Hz to 23 Hz. Thus, even more advanced ultrasound techniques, such as shear wave elastography might be developed using the python language without compromising the frame rate.
Experimental modeling of mass eruption rates from acoustics wave
Authors: Sánchez Claudia , Ripepe Maurizio , Lacanna Giorgio , Poggi Pascuale
Published: November 2019

Among the different volcanoes dynamics encountered worldwide, the repetitive bursting of giant, elongated gas bubbles (“slugs”) occupying the whole conduit diameter is a feature commonly described as Strombolian activity. One of the key parameters to understand this eruptive behavior is the estimate of the overpressure ΔP inside the bubble before its explosion, which may occur either at the volcano vent or inside the conduit. This quantification, however, is still a major challenge. On the one hand, it has been shown that for weak acoustic waves (linear regime), the amplitude of the pressure wave propagating in the atmosphere due to the bursting does not depend linearly on ΔP. On the other hand, the gas pressure inside volcanic bubbles may strongly vary and sometimes exceed the atmospheric pressure by up to several MPa, exhibiting non-linear acoustic regimes. We investigate experimentally the acoustic signal released by a cylindrical, overpressurized cavity initially closed. We explore the transition between the linear and non-linear regimes and their relationship with the velocity fluid and mixture particles on the system for estimating the mass flow rate using Lighthill's equation.
Fundamental frequency correlates with head movement evaluated at two contrasting speech production rates
Authors: Tiede Mark , Chen Wei-Rong , Whalen D. H.
Published: November 2019

The 720 phonetically balanced IEEE sentences have been recorded from eight speakers using electromagnetic articulometry (EMA) at "normal” and "fast” production rates. Participants self-selected their preferred normal rate and were instructed to produce the fast rate as quickly as possible without making errors (errorful productions were immediately repeated), resulting in an average 66.3% (0.4) duration reduction. EMA trajectories were recorded at 100 Hz with 44 100 Hz synchronized audio. The centroid of sensors attached to the upper incisors and the mastoid processes was used to characterize the 6DOF (X, Y, Z, roll, pitch, and yaw) deviation of the head in each sample from an initial occlusal plane reference position. Fundamental frequency, downsampled to 100 Hz, was correlated with this head movement signal using multiple linear regression. Mean adjusted R-squared values were uniformly higher for the faster production across all speakers: normal 0.77 (0.19) and fast 0.84 (0.18). Inclusion of jaw position as a regressor improved results to normal 0.89 (0.12) and fast 0.93 (0.11). The higher correlation at faster rates may be due to influence of observed increased head movement on laryngeal setting (and thus fundamental frequency) as production stress increases. These results have implications for the synthesis of head movement from acoustics and automatic modulation of synthetic voicing sources (electrolarynx). [Work supported by NIH.]
Efficacy and safety data for the XEN45 implant at 2 years: a retrospective analysis
Authors: Gabbay Itay Elimelech , Allen Felicity , Morley Christine , Pearsall Tahmina , Bowes Oliver Martyn , Ruben Simon
Published: November 2019

Aim

To report efficacy and safety measures for XEN45 in a National Health Service setting after 24-month follow-up.

Methods

This is a retrospective, non-comparative audit of records of patients who underwent XEN45 procedure between June 2015 and May 2017. The main outcome measures were intraocular pressure (IOP) reduction and number of antihypertensive medications at each timepoint. Failure was defined as requiring further surgery or removal of XEN. Success was defined as 20% reduction of IOP without additional glaucoma medications or reduction in antihypertensive medications without increase in baseline IOP. Needling rates were assessed and subgroup analysis was performed.

Results

A total of 151 eyes were included in the study. The main diagnoses were primary open angle glaucoma (84.1%), angle closure glaucoma (8.6%) and refractory glaucoma (7.3%). Stand-alone procedure was performed in 62.3% and combined phaco-XEN was done in 37.7%. The mean IOP at baseline was 22.1±6.5 mm Hg, and the mean IOP at 12 and 24 months was 15.4±5.9 mm Hg and 14.5±3.3 mm Hg, respectively (p<0.001). The mean number of medications was 2.77±1.1 at baseline, and 0.3±0.7 and 0.5±1.0 medications at 12 and 24 months, respectively (p<0.001). 25% of patients failed at the 24-month timepoint. Needling was required in 37.7% of patients at 24 months. Non-Caucasian ethnicity was found to be related to higher failure rate. No significant adverse events were noted.

Conclusion

XEN45 is a viable, effective and safe procedure after 2 years of follow-up. Patients should be advised regarding failure rate as well as possible need for bleb revisions and medication use.
Cost and cost-effectiveness of point-of-care testing and treatment for sexually transmitted and genital infections in pregnancy in low-income and middle-income countries: a systematic review protocol
Authors: Saweri Olga PM , Batura Neha , Adawiyah Rabiah al , Causer Louise , Pomat Willie , Vallely Andrew , Wiseman Virginia
Published: November 2019

Introduction

The economic and health burden of sexually transmitted and genital infections (henceforth, STIs) in low-income and middle-income countries (LMICs) is substantial. Left untreated, STIs during pregnancy may result in several adverse pregnancy and birth outcomes. Timely diagnosis and treatment at point-of-care (POC) can potentially improve these outcomes. Despite the availability and promotion of POC diagnostics for STIs as a key component of antenatal care in LMICs, their widespread use has been limited, owing to the high economic costs faced by individuals and health systems. To date, there have been no systematic reviews which explore the cost or cost-effectiveness of POC testing and treatment of STIs in pregnancy in LMICs. The objective of this protocol is to outline the methods that will compare, synthesise and appraise the existing literature in this domain.

Methods and analysis

We will conduct literature searches in MEDLINE, Embase and Web of Science. To find additional literature, we will search Google Scholar and hand search reference lists of included papers. Two reviewers will independently search databases, screen titles, abstracts and full texts; when necessary a third reviewer will resolve disputes. Only cost and cost-effectiveness studies of POC testing and treatment of STIs, including syphilis, chlamydia, trichomonas, gonorrhoea and bacterial vaginosis, in pregnancy in LMICs will be included. Published checklists will be used to assess quality of reporting practices and methodological approaches. We will also assess risk of publication bias. Interstudy heterogeneity will be assessed and depending on variation between studies, a meta-analysis or narrative synthesis will be conducted.

Ethics and dissemination

Ethical approval is not required as the review will use published literature. The results will be published in a peer-reviewed open source journal and presented at an international conference.

PROSPERO registration number

CRD42018109072.