bluuebunny/crossref_metadata_2025 huggingface dataset:
Fluctuations and trends in spatio‐temporal patterns of plant species and diversity in a sandy pasture
Authors: Fóti Szilvia , Bartha Sándor , Balogh János , Pintér Krisztina , Koncz Péter , Biró Marianna , Süle Gabriella , Petrás Dóra , De Luca Giulia , Mészáros Ádám , Zimmermann Zita , Szabó Gábor , Csathó András István , Ladányi Márta , Péli Evelin Ramóna , Nagy Zoltán
Published: April 2023

Aims

The relative importance of species within an ecosystem shows spatio‐temporal variability related to both the terrain features and numerous rapidly changing factors. Accordingly, functional and species patterns may show some level of persistence, or, due to various disturbances, fluctuations. Communities with high species richness were found to maintain a higher degree of stability than species‐poor or perturbed vegetations; however, diversity and its stability may be spatio‐temporally variable. Based on these considerations, our aim was to assess the responses of a sandy pasture, both species‐wise and at the community level, to the relatively invariant habitat, and to the more rapidly changing environmental conditions.

Location

Hungary.

Methods

We surveyed the vegetation in an area of about 1 ha by means of high‐resolution spatio‐temporal sampling: we recorded the surface aerial cover (%) of the plant species during 15 campaigns covering spring, summer and autumn aspects for seven years (2013–2019) in 80 × 60 m grids. The biological activity of the ecosystem (above‐ground biomass, soil respiration) was also followed up together with the environmental limiting factors.

Results

During the study period, which was characterized by significant warming, the grassland showed a balanced physiological performance with year‐to‐year variability. Fluctuating differentiation of the plant species with different environmental optima along with the terrain attributes was assumed to be responsible for this balanced physiological performance. Although community‐level diversity remained stable, some species favoring cooler, wetter positions disappeared.

Conclusions

Terrain features of the study area within 1.5 m or less elevation differences created considerably heterogeneous conditions for a high number (114) of plant species with different ecological needs to co‐occur. The stability of the diversity was found to show terrain relatedness, that is spatial as well as temporal patterns compared to the null model of spatio‐temporal independence, and the ecosystem functions followed these patterns.
A review of influencing factors on a recirculating aquaculture system: Environmental conditions, feeding strategies, and disinfection methods
Authors: Li Hao , Cui Zhengguo , Cui Hongwu , Bai Ying , Yin Zhendong , Qu Keming
Published: April 2023

Recirculating aquaculture system (RAS), as a modern highly intensive aquaculture mode, demonstrates the advantages of environmental friendliness, high efficiency and sustainable development, and has been widely used worldwide; they are also expected to be more widely applied in industrial aquaculture in the future as our natural resources are decreasing. However, RAS imposes very high requirements on operating conditions, including temperature, salinity, dissolved oxygen, pH, stocking density, light, feed composition, feeding amount, feeding frequency, and disinfection methods. Each factor is critical to the stable operation of the system. Therefore, to ensure the efficient and stable operation of RAS, its influencing factors must be controlled to within appropriate ranges. Herein, the factors affecting the operation of RAS are reviewed, and the mechanisms of their influence on the reared organisms are revealed, and suggestions on the control of these factors in aquaculture are proposed. This review can provide a theoretical basis for the further development of RAS.
Patterns of load distribution among the legs in small water striders during standing and striding
Authors: Meshkani J. , Rajabi H. , Kovalev A. , Gorb S. N.
Published: April 2023

Water striders (Gerris argentatus) move across the water surface by taking advantage of the surface tension, which supports their bodyweight without breaking. During locomotion, the midlegs are primarily responsible for generating thrust, whereas the other legs support the body. Although the aspects of standing and locomotion on the water surface are well understood, relatively fewer studies concerned the coordinated biomechanical movements of the legs. In order to maintain buoyancy of the body on the water surface, the leg positions must be adjusted to distribute the bodyweight appropriately. The present study investigates distribution of the bodyweight on the legs in relatively small water striders. We aimed to understand how loading on the legs changes during sculling that leads to sliding of the body on the water surface. The assistance of all legs at every moment enables the body to maintain its floating during standing and striding. Water striders can achieve a gentle striding through the midlegs driving phase in association with smooth load shifting among their legs, which are positioned in a specific configuration to support the insect on the water surface.
A Meta‐Analysis of Interventions to Improve Reading Comprehension Outcomes for Adolescents with Reading Difficulties
Authors: Sohn Hyojong , Acosta Kelly , Brownell Mary T. , Gage Nicholas A. , Tompson Eilish , Pudvah Carolyn
Published: April 2023

This meta‐analysis synthesized 97 effect sizes extracted from 37 intervention studies for students with reading difficulties (RDs) in Grades 6 to 12 published between 1982 and 2021 to identify the overall impact of reading interventions and the moderating effects of intervention characteristics and study design characteristics. Random‐effects robust variance estimation (RVE) was used to account for dependencies within studies. Overall, interventions designed to improve reading comprehension outcomes for adolescents with RDs were effective (g = 0.63). Meta‐regression analyses identified several significant moderators that were associated with intervention efficacy, such as text content, duration of intervention, agent of intervention, status of student, type of dependent measure, and study quality. We provide study limitations as well as implications for research and practice.
Towards a critical translanguaging biliteracy pedagogy: the ‘aha moment’ stories of two Mandarin Chinese teachers in Canada
Authors: Jin Jing , Liu Yina
Published: April 2023

Learning Mandarin Chinese as a heritage or additional language at Chinese complementary schools has long been a tradition for many Asian Canadians. However, research that looks at teachers' experiences and perceptions in Canadian settings, especially the power dynamics embedded in biliteracy development at complementary schools, is scant. Moreover, the COVID‐19 pandemic brought challenges and opportunities to Chinese complementary schools. In this paper, we, as two Mandarin teachers and literacy researchers, used collaborative autobiographical narrative inquiry to tell our stories to unfold (1) how power dynamics regarding biliteracy/multiliteracy were enacted and reflected in a Chinese complementary school during the pandemic and (2) our re‐understanding of Mandarin teaching and learning from critical literacy and translanguaging perspectives. Although the pandemic is over, racial discrimination and social inequity continue to remain in our lives. By analysing our teaching moments and reflections, we hope this study could provide some insights into how critical literacy and translanguaging can be integrated into language and literacy education in multilingual and multimodal settings in the pandemic and post‐pandemic contexts.
Exploring phonetic predictors of intelligibility, comprehensibility, and foreign accent in L2 Spanish speech
Authors: Nagle Charlie L. , Huensch Amanda , Zárate–Sández Germán
Published: April 2023

Although current approaches to second language (L2) pronunciation underscore that instruction should concentrate on pronunciation features that help learners be more intelligible (and not necessarily more native like), there is little empirical evidence as to what those features are, especially in languages other than English. To address this gap, this exploratory study examined phonetic predictors of listener‐based dimensions—namely, intelligibility, comprehensibility, and foreign accent—in L2 Spanish speech. Samples were taken from 42 Spanish learners of varying proficiency while performing a picture description task, rated for global measures by 80 native Spanish listeners, coded for phonemic errors, and analyzed phonetically for pronunciation features that previous research has reported as challenging for English‐speaking learners. Mixed‐effects models were fit to the data to examine relationships between the phonetic features and the listener‐based dimensions. Results revealed that rising intonation and diphthongization of word‐final /o/ predicted intelligibility, rising intonation predicted comprehensibility, and a variety of features were associated with foreign accent. Overall, results confirmed that non‐target‐like production of L2 pronunciation, including areas known to be challenging for Spanish learners, does not necessarily lead to intelligibility and comprehensibility issues. Based on these findings, we make recommendations regarding what features should be prioritized in L2 pronunciation instruction.
Styles of regulatory discretion: A comparative analysis of the British and Israeli education legislation
Authors: Kosti Nir
Published: April 2023

Regulatory discretion is a central theme in the study of regulation and governance. However, little attention has been paid to the question of how countries vary in the way they design regulatory discretion. This article fills this gap by conceptualizing styles of regulatory discretion according to a novel conceptual framework that distinguishes between three dimensions of regulatory discretion: obligation, content, and procedure. Empirically, the article compares regulatory discretion in British and Israeli education legislation during the period 1948–2020. The findings reveal substantial differences in regulatory discretion styles between the two countries across all three dimensions of regulatory discretion. Accordingly, this article proposes several links between regulatory discretion and regulatory production that can be explored further. In doing this, the article points to the relationship between discretion practices and regulatory outcomes.
Interdependence between climate change and migration: Does agriculture, geography, and development level matter in sub‐Saharan Africa?
Authors: Bannor Frank , Magambo Isaiah Hubert , Mahabir Jugal , Tshitaka Jeanluc Mubenga
Published: April 2023

Concerns about the human effects of climate change have contributed to forecasts of how populations in drought‐prone and flood‐prone areas would respond to these events. Empirical studies have predicted that human migration has been among the critical resilient strategy in responding to the impact of climate change. To obtain a more comprehensive understanding of the climate–migration relationship, the impacts of climate change on international migration flows from sub‐Saharan Africa nations to South Africa are investigated empirically in this paper. The study employed static and dynamic models and panel data from 35 countries in sub‐Saharan Africa, spanning 1990 to 2017. The findings are as follows: (1) The analysis shows that historical temperature has a positive and statistically significant effect on outmigration in agriculture‐dependent nations. (2) The analysis shows that agricultural value added as a share in gross domestic product has a negative and statistically significant effect on outmigration in agriculture‐dependent nations. (3) The results also show that geographic location and development level of a country, in addition to dependency on agriculture, are key factors in the climate change–international migration nexus. Policy implications are discussed.
What is the best model of grit among junior high students: Model selection, measurement invariance, and group difference
Authors: Weng Min‐Chieh , Liao Chen‐Hsuan , Kwok Oi‐Man , Wu Jiun‐Yu
Published: April 2023

Grit is a non‐cognitive construct based on personality theory that fosters individuals to perform better and achieve their goals. Previous researchers validated the psychometric properties of grit for adults and older adolescents but ignored that for early adolescents. An inappropriate measurement model may mislead researchers and teachers to misapprehend grit measures. This study aimed to identify the most appropriate grit model for early adolescents. Three factorial models (i.e., two‐factor, one‐factor, and bi‐factor models) were evaluated and compared. Subsequently, we tested the measurement invariance (MI) and mean differences of grit across grade and gender groups. Participants were 672 junior high students (51% boys, aged 12–15) in Taiwan. The results showed that the two‐factor model was the best grit model. This finding revealed that adolescents tend to comprehend grit with two distinct concepts, consistency in interest (CI) and perseverance of effort (PE), instead of a single compound. In addition, the results showed that the two‐factor model retained strong invariance for grade and gender, justifying the comparison of grit scores over grade and gender groups for junior high students. Moreover, we did not find any group difference in the facets of grit by gender and grades. This result showed that grit is a stable personality for junior high students. The relationships between grit constructs and criteria, such as conscientiousness and academic achievements, were tested and discussed.
Lymphotropic nanoparticle magnetic resonance imaging for diagnosing metastatic lymph nodes in dogs with malignant head and neck tumours
Authors: Griffin Lynn R. , Frank Chad , Rao Sangeeta , Seguin Bernard
Published: April 2023

Lymphotropic nanoparticle magnetic resonance imaging (LNMRI) utilises ultrasmall paramagnetic iron nanoparticles (USPIOs) for imaging of metastatic lymph nodes in patients afflicted with cancer. LNMRI has been shown to be a highly effective and accurate way to diagnose metastasis in humans but has not been commonly reported on in veterinary medicine. USPIOs are phagocytised by macrophages and then localised to lymph nodes where they create a susceptibility artefact on gradient echo MRI sequences. In this study dogs (n = 24) with naturally occurring head and neck tumours were imaged with LNMRI then had mandibular and retropharyngeal lymph nodes extirpated for histological analysis. Subjective and objective analysis of the LNMRI images was performed and imaging results compared to histology as the gold standard. A total of 149 lymph nodes were included in this study. The overall sensitivity, specificity and accuracy was 64%, 94.4% and 89.3% respectively. However, if dogs with mast cell tumours were excluded from analysis the sensitivity, specificity and accuracy rose to 85.7%, 95.7% and 94.6%. LNMRI is potentially an accurate way to determine the presence of lymph node metastasis in dogs with some types of head and neck tumours. However, LNMRI has only moderate accuracy in dogs with oral or mucocutaneous mast cell tumours in this region.
Fully Coupled Analysis of Flutter Induced Limit Cycles: Frequency Versus Time Domain Methods
Authors: Berthold Christian , Gross Johann , Frey Christian , Krack Malte
Published: April 2023

To save resources and reduce emissions, it is crucial to reduce weight of aircraft engines and further increase aerodynamic efficiency of gas and steam turbines. For turbine blades, these goals often lead to flutter. Thus, innovative flutter-tolerant designs are explored, where flutter induces limit cycle oscillations (LCOs) of tolerable yet nonzero levels. Flutter represents a self-excitation mechanism and, in the linear case, would lead to exponential divergence. Flutter-induced LCOs are therefore an inherently nonlinear phenomenon. The saturation of flutter-induced vibrations can be caused by nonlinear frictional contact interactions, e.g., in tip shroud interfaces. To develop flutter-tolerant designs, efficient methods are required which compute LCOs based on an appropriate modeling of elastic, inertia, aerodynamic, and contact forces. We recently developed a Frequency Domain Fluid-Structure Interaction (FD-FSI) solver for flutter-induced LCOs. The solver relies on the Harmonic Balance method applied to the structure as well as the fluid domain. It was shown that especially for long and slender blades with friction in shroud interfaces and strong aerodynamic influence, a coupled analysis can significantly increase the accuracy of predicted LCOs compared to the current state-of-the-art methods. Conventional methods do not properly account for the nonlinear change of frequency and deflection shape, and the effect of these changes on the aerodynamic damping, and thus fail in predicting certain LCOs at all. In the current work, the FD-FSI solver is numerically validated against Time Domain Fluid-Structure Interaction (TD-FSI) simulations. As a test case, a shrouded low-pressure turbine with friction in the shroud interfaces is considered. The point of operation is highly loaded and transonic in order to make the test case challenging. Apart from a successful validation of the FD-FSI solver, we shed light on important advantages and disadvantages of both solvers. Due to the lack of robust phase-lag boundary conditions for time domain solvers, a full blade row must be simulated. Thus, the FD-FSI solver typically requires only a fraction of the computational costs. Moreover, the FD-FSI solver contributes to an increased physical understanding of the coupled vibrations: By analyzing the contribution of individual harmonics, we analyze why unexpected even harmonics appear in a certain LCO. On the other hand, the FD-FSI solver does not provide information on the asymptotic stability of the LCOs and is strictly limited to periodic oscillations. Indeed, quasi-periodic limit torus oscillations (LTOs) appear in our test case. Using the TD-FSI solver, we confirm the internal combination resonance, postulated recently as necessary condition for LTOs, for the first time, in a fully coupled analysis.
Combining passive acoustic monitoring and species distribution models to monitor species responses to climate change
Authors: Campos-Cerqueira Marconi
Published: April 2023

Climate change is altering the spatial distribution of many species worldwide, even in pristine and protected areas. Therefore, we need to identify and protect suitable areas for a large proportion of the fauna so that they persist through time. Here, we combined passive acoustic monitoring, semi-automatic species identification models, and species distribution models to document shifts in bird and frog distributions along an elevational gradient. In addition, we used acoustic data from 674 sites from Puerto Rico's main island to create species distribution models based on past (1980–1989), present (2005–2014), and future (2040–2060) climate scenarios to determine how species distributions relate to the current distribution of protected areas. Our results suggest that species are shifting toward high-elevation areas. We also showed that Puerto Rico is projected to become dryer by 2040–2060, and precipitation in the warmest quarter was among the most important variables affecting bird distribution across the entire island. In addition, a large portion of always-suitable areas for birds is outside of protected areas (>75%), indicating that present protected areas will not suffice to safeguard bird species under climate change. We must be creative and proactive in protecting species in climate change scenarios.
Odontocete foraging vocalizations during various Cold Pool states in the Bering Sea
Authors: Seger Kerri D. , Miksis-Olds Jennifer , Johnson Jennifer J.
Published: April 2023

The Cold Pool is a subsurface layer (<2°C) that is formed in the summer from stratification and is characterized by previous winter conditions. This bottom layer of relatively cooler temperatures impacts zooplankton dynamics, driving two different energetic pathways. The cold regime pathway favors larger zooplankton species, which increases forage fish biomass while the warm regime pathway favors smaller zooplankton species, which decreases forage fish biomass. Since odontocetes rely on forage fish for survival and use echolocation to find them, tracking foraging vocalizations could lead to a better understanding of the implications of a variable Cold Pool on the Bering Sea’s food web. The Cold Pool was more variable in warm regime years (2014–2017) relative to cold regime years (2007–2013) and was absent in 2018 at this study site. Concurrently, acoustic data with odontocete vocalizations were collected. This presentation will discuss whether odontocete vocal presence is related to Cold Pool dynamics and if odontocete foraging behavior changes as a function of Cold Pool variability. Since a reduced presence of the Cold Pool could occur more often with climate change, it is important to monitor the higher trophic levels’ foraging activities to predict what ecosystem changes could occur in the future.
Decadal scale trends in temperature, salinity, and sound speed in the Beaufort Sea since 1976
Authors: Reeder D. Benjamin , Joseph John E.
Published: April 2023

Profiles of conductivity and temperature as a function of depth (CTD) were collected in the Beaufort Sea during two U.S. Navy Ice Exercises in 2016, 2018, and 2020 (ICEXYY) in the month of March. The data show a significant departure from climatological values and significant variance at the interface between the Arctic Surface Layer (ASL) and the underlying Pacific Summer Water (PSW). Comparisons to older ICEX data collected over a 45 year period and to ice-tethered profiler (ITP) data since 2007 confirm both the subsurface warming trend and the variance at the ASL-PSW interface. Statistical analysis reveals a 0.4 degreeCelsius per decade increase in the near-surface temperature maximum (NSTM) near 75 m, which establishes two persistent acoustic propagation features beginning in the year 2000—a near-surface acoustic duct above 50 m and a subsurface acoustic duct, known as the Beaufort Lens, centered on 150 m water depth.
Nonlinear ultrasound imaging of the microcirculation
Authors: Bruce Matthew , Harmon Jennifer N. , Arkadevitch Anton , Khaing Zin
Published: April 2023

Blood flow at and near the tissue level is a physiological parameter of significant experimental and clinical importance, as it reflects the adaptive response of organs to their normal biological environment, to disease, trauma, and the malignant progression of cancer. The use of microbubbles gives ultrasound imaging access to microvascular hemodynamics, which are beyond the ability of Doppler ultrasound methods. However, expanded clinical use of microbubbles has been limited due in part to a lack of quantification and providing only relative differences in microvascular flow. Past and more recent approaches to the quantification of microvascular blood flow will be presented. Past approaches included the use of focused nonlinear pulsing sequences to isolate microbubble from tissue signals followed by analysis of bolus kinetics or flash replenishment dynamics. Although successfull to some extent, their clinical limitations prohibited extended use and the overall application of contrast enhanced ultrasound (CEUS). Newer approaches include higher frame-rate plane wave acquisitions combined with nonlinear pulsing schemes, which enable the tracking of microbubble flow through microvascular networks. Different approaches of these elevated frame-rate acquisitions will be presented, including use of ultrasound localized microscopy.
Direct spatiotemporal localization of microbubble trajectories for highly resolved hemodynamics in ultrasound localization microscopy
Authors: Leconte Alexis , Porée Jonathan , Rauby Brice , Xing Paul , Bourquin Chloé , Ghigo Nin , Ramos Gerardo , Sadikot Abbas F , Provost Jean
Published: April 2023

Using high concentrations of microbubbles in ultrasound localization microscopy can reduce acquisition time but is also associated with reduced localization precision and accuracy of blood flow measurements. To address these limitations, we introduce Ultrasound Spatio-Temporal Localization (USTL), a novel approach that localizes microbubble trajectories using a spatiotemporal physiological constraint, in contrast to standard approaches that detect, pair, and track microbubbles over time without a priori. We tested USTL in vivo in the brains of rats and mice using a 15 MHz linear array probe and a Vantage system at different concentrations of microbubbles. Overall, USTL increased the number of detected microbubbles while reducing processing time and susceptibility to signal attenuation at depth. USTL provided coherent velocity profiles in vessels regardless of microbubble concentration, making it a valuable tool for studying brain hemodynamics in various conditions. Overall, USTL offers a new approach for the non-invasive measurement of dynamic brain function with high spatial and temporal resolution.
An in silico model of clot degradation under the action of histotripsy and thrombolytic drugs
Authors: Bader Kenneth B.
Published: April 2023

For venous thrombosis patients, catheter-directed thrombolytic drugs remain the standard-of-care to restore vascular flow. Improved outcomes are observed when thrombolytic drugs are combined with histotripsy, a focused ultrasound therapy that breaks down tissue via bubble activity. To gain insight into the mechanisms of this combination approach, an in silico model of bubble/thrombolytic/clot interaction was developed. A Monte Carlo-like simulation was used to gauge the extent of histotripsy ablation. The local tissue properties that dictate bubble nucleation were adjusted based on annotated histological sections of venous thrombi. The distribution of thrombolytic drug within the clot was computed using a finite-difference time domain solution of the perfusion-diffusion equation. Fibrin degradation was computed using the known reaction rate of thrombolytic drug. Predictions of ablation were dependent on the clot subgroup, with a reduction in the extend of ablation as the concentration of fibrin increased. Thrombolytic drug was more uniformly distributed throughout the clot when the effects of histotripsy ablation were consistent, consistent with recent in vitro measurements. Overall, the findings here indicate histotripsy primarily enhances the activity of thrombolytic drugs is via debulking red blood cells within a clot.
Mechanistic study of blood brain barrier opening by microbubbles and focused ultrasound
Authors: Hu Lu Na , Jung Olive , Ruan Jia Ling , Petersson Kristoffer , Ferrer Marc , Stride Eleanor P.
Published: April 2023

Drug delivery to the brain is restricted by the blood brain barrier (BBB), limiting up to 98% small molecule drugs and almost 100% biologics. This severely limits the treatment options for diseases of the CNS. The use of microbubbles (MBs) in combination with focused ultrasound (FUS) has successfully delivered multiple classes of therapeutics through the BBB, although the molecular mechanism of the BBB opening, and associated adverse effects, are yet to be fully understood or characterised. The aim of this study was to perform simultaneous imaging of microbubble dynamics and cellular response under different ultrasound exposure conditions in a two-dimensional in vitro endothelial model with and without MBs present. The results indicate that changes in cell-cell junctions dominated over sonoporation and/or other mechanisms of cellular uptake of a fluorescent drug surrogate. Investigation was also made of the signalling pathways associated with paracellular permeability and sterile inflammation.
Numerical simulation and experimental studies on acoustofluidic separation of microparticles using 3D printed chips
Authors: Karaman Alara , C¸etin Barbaros , Özer Mehmet Bülent
Published: April 2023

Principles of acoustofluidics can be used to manipulate and separate microparticles and cells in microchannels. In this study using numerical simulations, we will be investigating the limits of fundamental assumptions used in acoustofluidic such as a limited acoustic scattered field or fluid flow interaction between the particles/cells. A device-level numerical simulation tool will be used which accounts for the effect of the piezoelectric materials, interactions between the microparticles/cells fluid flow-field and the acoustic-field in the microchannel. Also, in this study, different numerical acoustic and mechanical models of biological cells will be investigated and the conditions (frequency, channel dimensions, etc.), which favor the acoustofluidic separation of cells with similar mechanical properties will be studied numerically. Finally, the results of the numerical simulations will be utilized, and experimental studies will be demonstrated, which separate microparticles/cells in a 3D printed polymeric chip.
What would a Webchuck Chuck?
Authors: Chafe Chris , Wang Ge , Mulshine Mike , Atherton Jack
Published: April 2023

Webchuck is a new platform for real-time web-based music synthesis. Combining expressive music programming power with the ubiquity of web browsers is a game changer, one which we've experienced in recent teaching at Stanford's CCRMA. The paper will describe how this has fulfilled a long-sought promise for accessible music making and simplicity of experimentation. The Chuck music programming language now runs anywhere a browser can and a link is all it takes. Sample-synchronous live coding alongside full-on studio functionality is what a Webchuck can Chuck, thanks to advances in the web audio API.
Low-complexity equalizers and applications
Authors: Zoelzer Udo
Published: April 2023

Equalizers for audio signal processing play an important role in microphones, mixing systems, mastering processors, monitor loudspeakers, and consumer devices such as smart tablets, smart phones, wireless headphones, and hearing devices. We will introduce low-complexity filter designs for equalizers based on first- and second order recursive filters. Low-complexity filter design means having the lowest number of parameters and design equations for first- and second-order difference equation realizing prescribed filter transfer functions such as low-pass, high-pass, band-pass, and all-pass filters. Based on these basic filters, we derive all-pass realizations of these standard filters and then apply them to design parametric low- and high-frequency shelving filters and peak filters. These last two versions of weighting filters are based on three parameters, namely, the cut-off or center frequency, the bandwidth or Q factor, and the gain in dB for a low-, mid-, or high frequency band and are, therefore, named parametric equalizers. These parametric equalizers' PEQs occur in a channel-strip of a mixing console and are an integral part of the mixing process. We will describe several further applications of PEQs for amp and loudspeaker modeling, headphone equalization and head-related transfer function modeling, and audio coding. All applications allow a low-complexity filter design, parameter update, and efficient recursive filter implementations with much lower complexity compared to non-recursive filters.
Design of sonar receivers for shallow water buried object imaging
Authors: Blanford Thomas E. , Philtron Jason , Brown Daniel C.
Published: April 2023

Downward looking synthetic aperture sonar can detect and localize proud and buried objects, such as unexploded ordinance (UXO), in very shallow water environments. These sensors generate three-dimensional imagery from a two dimensional array that is a hybrid of a synthetic and real aperture sonar. Achieving high-resolution imaging with these sensors places stringent requirements on the sonar hardware. The acoustic signals generated by the sensor are wide bandwidth, low frequency, and high dynamic range. Receiver spacing and directivity also play an important role in image quality but create competing design constraints at low frequency. This work will present the results of a recent design study to develop receivers for a buried UXO imaging system. Achieving the stringent hardware requirements necessitated that the transducers, baffle, housing, and electronics were designed in concert. Finite element and one-dimensional models were used to evaluate several candidate designs based upon piezocomposite, spherical, and hemispherical transducers and identify tradeoffs with each. The analysis will focus on both simulated and experimental results of the receiver components. Results from the component level also informed system level models to quantify the point spread function and resolution improvement of the sensor.
Assessing azimuthal asymmetry in the noise radiation from a three-core launch vehicle during liftoff
Authors: Moats Levi T. , Yancey Matthew G. , Hart Grant W. , Gee Kent L.
Published: April 2023

Creating accurate rocket noise models is important for assessing impacts on humans, the environment, and payloads. The United Launch Alliance Delta IV Heavy launch vehicle is unique because of the separation of the three cores and their associated RS-68A nozzles. This makes it a good candidate for determining how the asymmetry of nozzle configuration affects noise radiation, which can affect noise models. The NROL-82 and NROL-91 missions both launched from Vandenberg Spaceforce Base using Delta IV Heavy Vehicles. For both of these launches, acoustic data were recorded between ∼0.9 and ∼5.2 km from the vehicle at different azimuths to determine the extent of azimuthal asymmetry in noise radiation. Maximum overall sound pressure level, spectra, and overall power level were determined for each launch. Methods for comparing the datasets and results will be discussed.
Compound variance gamma distribution for randomly scattered sound and noise at multiple sensors
Authors: Wilson D. Keith , Ronan James G. , Ostashev Vladimir E.
Published: April 2023

Gamma distributions for signal intensity (or, equivalently, Nakagami distributions for signal amplitude) are often used in acoustics and electromagnetics to describe the single-point statistics of randomly scattered signals and noise in urban and other complex environments. An extension of the gamma distribution, called the compound gamma (CG), has been furthermore shown [D. K. Wilson, M. J. Kamrath, C. E. Haedrich, D. J. Breton, and C. R. Hart, “Urban noise distributions and the influence of geometric spreading on skewness,” J. Acoust. Soc. Am. 150(2), 783–800 (2021)] to usefully generalize the gamma to scenarios in which the distribution becomes skewed due to random variations in the scattering strength or loudness of the noise sources. Here we present the compound variance gamma (CVG), which further generalizes the compound gamma to two-point statistics and is, therefore, useful for representing statistics on arrays of sensors or networks. The CVG distribution, which is expressed with a Gauss hypergeometric function, is shown to be in excellent agreement with realistic simulations of sound scattering in the atmosphere.
Classifying urban areas from learned acoustic and seismic data
Authors: Baes Hans Matthew , Sandja Tchamba Herve , Abdulbasit Telha , Mahmoud Wagdy , Denis Max
Published: April 2023

In this work, a deep transfer learning algorithm is used to classify different urban areas from acoustic and seismic data. The deep transfer learning model combines Google’s deep learning model AlexNet. Measurements of acoustic and seismic ambient noise were conducted in an urban environment. The urban acoustic and seismic measurements are heavily influenced by traffic noise but exhibit more variation with respect to urban location due to the influence of subsurface conditions. A K-means clustering analysis is employed on the acoustic and seismic spectrogram to classify the urban areas. The results demonstrate that seismic and acoustic data can have similar cluster centroid locations in the frequency band of 4 Hz–10 Hz. The transfer learning results will be presented and discussed.
Laboratory measurements for objective evaluation of earplug fidelity
Authors: Anderson David A.
Published: April 2023

Musicians and concertgoers can easily be exposed to dangerously high noise doses that lead to hearing loss, and earplug use is often encouraged during loud musical performances. Traditional earplugs for industrial use can distort musical signals reaching the ear to the extent that users find their use disorienting and uncomfortable. High fidelity earplugs are designed to preserve musical sounds better than traditional earplugs by presenting a flat spectral attenuation of sound reaching the ears. At present, it’s not clear how to quantitatively compare different models in an analogous way to other devices in the high-fidelity sphere such as loudspeakers and amplifiers. In this presentation, a suite of laboratory measurements and derived metrics are proposed that lead to a comprehensive evaluation of earplug fidelity in terms of insertion loss levels, flatness, polar distortion maps, and temporal skewing. Initial results for a range of devices are presented, followed by a discussion of future directions.
From sounds to scenes: Comprehension of environmental sounds by cochlear implant users
Authors: Price Emily A. , Forrest Louisa M. , Luzum Nathan , Harris Michael S. , Heller Laurie M. , Shafiro Valeriy
Published: April 2023

Performance outcomes for cochlear implant (CI) users traditionally focus on measures of speech perception. However, existing research indicates that environmental sound identification tasks also remain challenging for adult CI users compared to normal-hearing (NH) or hearing-impaired (HI) peers. In contrast, anecdotal reports indicate that environmental sound perception improves post-implantation. Methodological choices may contribute to this discrepancy; CI users may be benefiting from more integrative higher-level processes that are not adequately measured by source identification tasks. This study employs two alternative tasks that are designed to assess perception of the semantic properties of environmental sounds. The first is a comprehension tasks, which requires listeners to make inferences about naturalistic sound scene recordings (e.g. which other activities might you expect to take place, or at which time of day does this scene most likely occur). The second task presents a triplet of isolated environmental sound recordings and requires participants to select the sound that does not belong. Preliminary data indicate that CI users are able to perform the tasks with varying levels of proficiency relative to NH and HI listeners. Comprehension tasks focused on context-dependent semantic processing may, thus, complement findings from more traditional single-sound identification tasks.
Utilization of acoustic cues to identify emotional prosody: Results in adults with normal hearing or cochlear implants
Authors: Kulkarni Aditya M. , Combs Jessica , Fitzpatrick Denis , Chatterjee Monita
Published: April 2023

Emotional prosody is a dominant source of information about a talker’s intended emotion. Multiple acoustic cues contrast different emotions. Voice pitch is a dominant acoustic cue for prosody, but individuals with cochlear implants do not have adequate access to this cue. Previous work has suggested that older individuals with normal hearing also have limited access to dynamic voice pitch contour cues. We are developing a cue-weighting method to estimate perceptual weighting of different prosodic cues in emotion identification by listeners with cochlear implants or normal hearing. Initial analyses indicate that in adult normally hearing listeners, increasing age reduces their weighting of voice pitch cues to emotion, but not their weighting of the secondary cue of duration. The perceptual weight for voice pitch is reduced when normally hearing listeners are attending to spectrally degraded (noise band vocoded) stimuli. Consistent with the latter observation, cochlear implant patients showed reduced weighting of voice pitch cues compared to normally hearing counterparts when both are attending to original (clean) stimuli. Taken together, these results suggest that increasing age and spectral degradation both reduce listeners’ ability to utilize voice pitch cues to emotional contrasts.
Localization and externalization of speech through hearing aids with adaptive features
Authors: Diedesch Anna C. , Best Virginia , Roverud Elin , Gallun Frederick J.
Published: April 2023

Hearing aids with advanced digital signal processing features that analyze acoustic scenes can amplify wanted sounds (e.g., speech) while utilizing complex noise reduction features to attenuate unwanted sounds (e.g., noise). These adaptive features can be programmed to be more or less aggressive in order to prioritize listening comfort or speech detail. Importantly, these adaptive features may alter the interaural cues of relevant target talkers located in front of the listener, causing unwanted effects on spatial perception. Here, we explored these effects. Spondees were presented from 11 different loudspeakers (located between ±75° azimuth separated by 15°) in an anechoic chamber. Binaural recordings were obtained from the ear canals of a Bruel & Kjaer Head and Torso Simulator, which was fitted with Oticon More hearing aids. The recordings were then presented over headphones to listeners, who indicated the perceived direction and degree of externalization of the spondees. Several conditions were tested, which differed in the acoustics of the room (anechoic and simulated reverberation), the background (quiet and noise), and the hearing-aid coupling (unaided, open-fit, and occluded). Behavioral data will be compared to measured interaural cues in the corresponding binaural recordings.
Bandwidth extension with air and body-conduction microphones for speech enhancement
Authors: Lu Austin , Mittal Manan , Sarkar Kanad , Corey Ryan M. , Smaragdis Paris , Singer Andrew C.
Published: April 2023

Contact microphones are accelerometers placed on the skin to detect body-conducted speech, which is inherently robust to interfering sound sources. However, contact microphones are severely bandlimited. In contrast, standard air-conduction microphones capture all relevant frequencies from all sources. To partially recover lost frequency components of speech, we can use bandwidth extension, which uses formant information at low frequencies to reconstruct the spectral envelope and harmonic structure. We use a suite of bandwidth extension methods to combine high SNR, low bandwidth audio with low SNR, full bandwidth audio for speech enhancement.
Laser-acoustic detection of objects buried underwater
Authors: Liu Guoqin , Aranchuk Vyacheslav , Zhang Likun , Hickey Craig J.
Published: April 2023

An object buried underwater such as landmines can potentially be excited to vibrate by a sound source in air. The vibration then radiates a secondary wave in the water to excite the water surface vibration which can be detected by a laser sensor. This idea of laser-acoustic detection of buried objects is effective in detecting objects buried under ground where the object is mechanically excited and the ground surface vibration is scanned by the laser sensor. When applying this approach to detect objects buried underwater, the addition of the water layer has an impact on the flexibility of the detection. Numerical simulations and laboratory experiments are conducted to assess this flexibility. Vibrations of the object and the water surface are experimentally measured and numerically simulated for water layers of different depths. The results reveal the impact of the water layer and the effectiveness of the detection. [Work supported by the Office of Naval Research under Award No. N00014-21-1-2247.]
Advanced applications of the continuous-scan acoustic measurement method
Authors: McShane John , Shah Parthiv , Kerrian Peter , Yang Michael , White Andrew
Published: April 2023

This presentation will cover recent progress in the development of continuous-scan acoustic measurement (CSAM) methods for imaging, reconstruction, and localization of spatially complex sound fields. CSAM comprises an acoustic array of slowly moving and fixed sensors coupled with position tracking to enable high-spatial-resolution partial field measurements for visualization and source characterization. In previous work, ATA has developed and demonstrated the use of a rotating array for beamforming and acoustical holography. This presentation will focus on one or more advanced applications of CSAM. Examples may include (1) quantifying spatial coherence from sound fields generated by multiple uncorrelated sources, (2) combining multiple test runs to visualize larger 2D spatial apertures and/or 3D sound fields, (3) combining high-resolution measurements with vibroacoustic models to predict scattered sound fields, and (4) exploring alternate array configurations (e.g., a spherical-surface measurement aperture).
Maximum entropy approach for sediment porosity and source strength of transiting ships
Authors: Nuttall Jacob R. , Neilsen Tracianne B. , Knobles David P. , Hodgkiss William
Published: April 2023

Remote sensing using passive sonar in the ocean is a challenging problem due to variations in the geoacoustic structure of the seabed and unknown source location and strength. One way to improve remote sensing is to perform an optimization for geoacoustic and source parameters. We use a Bayesian maximum entropy (BME) approach with a viscous-grain shearing parameterization for two sediment layers. The statistical optimization provides probability distributions for porosity and thickness of the sediment layers as well as ship speed, closest point of approach, and the source strength for the Wales-Heitmeyer empirical source level spectrum. We use this approach on spectrograms of transiting ships collected on a vertical line array during the 2017 seabed characterization experiment. We compare the resulting parameter distributions from distinct ships as well as previous estimates of geoacoustic values and source properties. This research shows that the BME approach obtains estimates for porosity and source strength that have narrow posterior probability distributions. [Work supported by the Office of Naval Research.]
Using 3-dimensional rendering programs to visualize 2-dimensional impulse responses of the built environment
Authors: Glosemeyer Petrone Robin
Published: April 2023

As the first notes from a performer are expressed on a newly constructed stage, we acousticians close our eyes and hold our breath. We do this not because our reputation is on the line but rather to focus all our attention on our auditory system. We listen for the impulse response, hearing the loudness, clarity, bass ratio, and profile of the decay. We open our eyes as the performer continues, pairing our visual and auditory senses to gain still more information. We look for those surfaces placed around the stage to support the direct sound. We follow the vibrations into the larger volume and map their path as they bounce around the room and rain down a shower of energy that envelops us in warm sonic embrace. Did we achieve the acoustic signature we designed? We will discuss our methods for mapping out the recording of two-dimensional time and energy in an impulse responses onto three-dimensional space with rendering software in order to analyze and tune our performances spaces.