bluuebunny/crossref_metadata_2025 huggingface dataset:
A Comparative Cancer Risk Evaluation of MTBE and Other Compounds (Including Naturally Occurring Compounds) in Drinking Water in New Hampshire
Authors: Beyer Leslie A. , Greenberg Grace I. , Beck Barbara D.
Published: December 2020

Methyl tert‐butyl ether (MTBE) was added to gasoline in New Hampshire (NH) between 1995 and 2006 to comply with the oxygenate requirements of the 1990 Amendments to the Clean Air Act. Leaking tanks and spills released MTBE into groundwater, and as a result, MTBE has been detected in drinking water in NH. We conducted a comparative cancer risk assessment and a margin‐of‐safety (MOS) analysis for several constituents, including MTBE, detected in NH drinking water. Using standard risk assessment methods, we calculated cancer risks from exposure to 12 detected volatile organic compounds (VOCs), including MTBE, and to four naturally occurring compounds (i.e., arsenic, radium‐226, radium‐228, and radon‐222) detected in NH public water supplies. We evaluated exposures to a hypothetical resident ingesting the water, dermally contacting the water while showering, and inhaling compounds volatilizing from water in the home. We then compared risk estimates for MTBE to those of the other 15 compounds. From our analysis, we concluded that the high‐end cancer risk from exposure to MTBE in drinking water is lower than the risks from all the other VOCs evaluated and several thousand times lower than the risks from exposure to naturally occurring constituents, including arsenic, radium, and radon. We also conducted an MOS analysis in which we compared toxicological points of departure to the NH maximum contaminant level (MCL) of 13 µg/L. All of the MOSs were greater than or equal to 160,000, indicating a large margin of safety and demonstrating the health‐protectiveness of the NH MCL for MTBE.
Smoothing Splines on Riemannian Manifolds, with Applications to 3D Shape Space
Authors: Kim Kwang-Rae , Dryden Ian L. , Le Huiling , Severn Katie E.
Published: December 2020

There has been increasing interest in statistical analysis of data lying in manifolds. This paper generalizes a smoothing spline fitting method to Riemannian manifold data based on the technique of unrolling, unwrapping and wrapping originally proposed by Jupp and Kent for spherical data. In particular, we develop such a fitting procedure for shapes of configurations in general m-dimensional Euclidean space, extending our previous work for two-dimensional shapes. We show that parallel transport along a geodesic on Kendall shape space is linked to the solution of a homogeneous first-order differential equation, some of whose coefficients are implicitly defined functions. This finding enables us to approximate the procedure of unrolling and unwrapping by simultaneously solving such equations numerically, and so to find numerical solutions for smoothing splines fitted to higher dimensional shape data. This fitting method is applied to the analysis of some dynamic 3D peptide data.
ADHD symptoms and callous‐unemotional traits as predictors of violent media use in adolescence
Authors: Rydell Ann‐Margret , Brocki Karin C.
Published: December 2020

We investigated ADHD symptoms and CU traits as predictors of violent media use in adolescence, controlling for delinquency and ODD symptoms. The effects on of disinhibition and arousal to negative stimuli, core characteristics of ADHD symptoms and CU traits, and of gender were investigated. At age 15, 88 adolescents, 50 % boys reported on CU traits, ADHD symptoms and delinquency. Parents rated the adolescents’ CU traits, ADHD‐ and ODD symptoms. At age 16, adolescents reported on their media habits and performed tests of disinhibition and arousal to negative stimuli. Boys had higher levels of CU traits and violent media use and girls had higher levels of arousal to negative pictures. CU traits and inattention symptoms predicted violent media use, the latter association applying only to boys, with CU traits being the strongest predictor. Low arousal to threat pictures explained variance in violent media use, above CU traits. Attraction to violent media seems affected by problem behaviors, with CU traits coming forth as especially important.
Smoking behavior and symptoms of depression and anxiety among young adult backpackers: Results from a short longitudinal study
Authors: Melamed Osnat C. , Walsh Sophie D. , Shulman Shmuel
Published: December 2020

Levels of smoking and smoking initiation have been found to increase during the transition to adulthood. Symptoms of depression and anxiety may both precede or follow smoking behavior, yet there is equivocal evidence regarding the direction of this relationship. The aim of the current study was to examine the direction of this relationship in a group of young adult backpackers who traveled to social environments which are permissive of smoking. The current study involved a quasi‐experimental design examining 199 (52% men, mean age 24.27, SD = 1.05 years at time 1) young adults, before, during and following a backpacking experience of at least six months. Regression analyses was used to examine the association between smoking and symptoms of depression and anxiety over time. Relative to smoking levels before the journey, a significant transient increase in smoking was found during the journey. The increase in smoking during the journey predicted increases in both depressive and anxiety symptoms following the journey. The reverse direction models were not significant. Our study suggests that social contexts which are permissive of smoking, such as backpacking, increase young adult smoking behavior. Mood symptoms did not contribute to the observed increase in smoking behavior but, inversely, increases in smoking contributed to heightened mood symptoms. Additional longitudinal studies are needed to explore the role that smoking behavior plays in young adults’ mental health.
Multimedia resources to support the recruitment of committed hematopoietic stem cell donors: Perspectives of the most‐needed donors
Authors: Li Edward W. , Lee Anna , Vaseghi‐Shanjani Maryam , Anagnostopoulos Alexander , Jagelaviciute Gabriele , Kum Elena , Petraszko Tanya , Elmoazzen Heidi , Allan David , Fingrut Warren
Published: December 2020

Background

Recruitment of committed unrelated hematopoietic stem cell donors from the most‐needed demographics remains a challenge for donor recruitment organizations worldwide. Multimedia resources are gaining attention as a modality to support recruitment efforts; however, there is a lack of guidance for the development of such tools. This qualitative study explores the perspectives of eligible stem cell donors on an educational whiteboard video about stem cell donation, generating insights into how whiteboard videos and related multimedia may be optimized for donor recruitment.

Study Design and Methods

Eight semistructured focus groups were conducted with 38 potential donors from the most‐needed demographics (young, male, and non‐Caucasian) after they had watched a 3.5‐minute whiteboard video explaining key concepts in stem cell donation (https://youtu.be/V4fVBtxnWfM). Constructivist grounded theory was used to identify themes and to develop a framework for understanding participants' preferred features of recruitment multimedia.

Results

Participants identified a range of features contributing to the effectiveness of recruitment multimedia, adding that the whiteboard video is an effective, integrated, and readily accessible format for supporting donor recruitment. Topics that participants felt are important to address include knowledge gaps regarding donation procedures, concerns about donor safety, and the particular need for specific donor demographics. Suggested avenues for improvement include the addition of donor/recipient/patient personal experiences, attention‐grabbing hooks, and a call to action including opportunities for further learning.

Conclusions

Several considerations were generated to inform the development of future multimedia for donor education/recruitment and are relevant to donor recruitment organizations worldwide.
A General Purpose Formulation for Nonsmooth Dynamics With Finite Rotations: Application to the Woodpecker Toy
Authors: Cosimo Alejandro , Cavalieri Federico J. , Galvez Javier , Cardona Alberto , Brüls Olivier
Published: December 2020

The aim of this work is to extend the finite element multibody dynamics approach to problems involving frictional contacts and impacts. The nonsmooth generalized-α (NSGA) scheme is adopted, which imposes bilateral and unilateral constraints both at position and velocity levels avoiding drift phenomena. This scheme can be implemented in a general purpose simulation code with limited modifications of pre-existing elements. The study of the woodpecker toy dynamics sets up a good example to show the capabilities of the NSGA scheme within the context of a general finite element framework. This example has already been studied by many authors who generally adopted a model with a minimal set of coordinates and small rotations. It is shown that good results are obtained using a general purpose finite element code for multibody dynamics, in which the equations of motion are assembled automatically and large rotations are easily taken into account. In addition, comparing results between different models of the woodpecker toy, the importance of modeling large rotations and the horizontal displacement of the woodpecker's sleeve is emphasized.
Childbirth Computational Models: Characteristics and Applications
Authors: Chen Sheng , Grimm Michele J.
Published: December 2020

The biomechanical process of childbirth is necessary to usher in new lives—but it can also result in trauma. This physically intense process can put both the mother and the child at risk of injuries and complications that have life-long impact. Computational models, as a powerful tool to simulate and explore complex phenomena, have been used to improve our understanding of childbirth processes and related injuries since the 1990s. The goal of this paper is to review and summarize the breadth and current state of the computational models of childbirth in the literature—focusing on those that investigate the mechanical process and effects. We first summarize the state of critical characteristics that have been included in computational models of childbirth (i.e., maternal anatomy, fetal anatomy, cardinal movements, and maternal soft tissue mechanical behavior). We then delve into the findings of the past studies of birth processes and mechanical injuries in an effort to bridge the gap between the theoretical, numerical assessment and the empirical, clinical observations and practices. These findings are from applications of childbirth computational models in four areas: (1) the process of childbirth itself, (2) maternal injuries, (3) fetal injuries, and (4) protective measures employed by clinicians during delivery. Finally, we identify some of the challenges that computational models still face and suggest future directions through which more biofidelic simulations of childbirth might be achieved, with the goal that advancing models may provide more efficient and accurate, patient-specific assessment to support future clinical decision-making.
Hip Joint Contact Loading and Muscle Forces During Running With a Transtibial Amputation
Authors: Sepp Lauren A. , Baum Brian S. , Nelson-Wong Erika , Silverman Anne K.
Published: December 2020

People with unilateral transtibial amputations (TTA) have greater risks of bilateral hip osteoarthritis, related to asymmetric biomechanics compared to people without TTA. Running is beneficial for physical health and is gaining popularity. However, people with TTA may not have access to running-specific prostheses (RSPs), which are designed for running, and may instead run using their daily-use prosthesis (DUP). Differences in joint loading may result from prosthesis choice; thus, it is important to characterize changes in peak and impulsive hip joint contact loading during running. Six people with and without TTA ran at 3.5 m/s while ground reaction forces, kinematics, and electromyography were collected. People with TTA ran using their own RSP and DUP. Musculoskeletal models incorporating prosthesis type of each individual were used to quantify individual muscle forces and hip joint contact forces (HJCFs) during running. People using RSPs had smaller bilateral peak hip joint contact forces compared to when wearing DUPs during stance and swing, and a smaller impulse over the entire gait cycle. Greater amputated leg peak hip joint contact forces for people wearing DUPs compared to RSPs occurred with greater forces from the ipsilateral gluteus maximus during stance. People with TTA also had greater bilateral peak hip joint contact forces during swing compared to people without TTA, which occurred with greater peak gluteus medius forces. Running with more compliant RSPs may be beneficial for long-term joint health by reducing peak and impulsive hip loading compared to DUPs.
Experimental comparison of acoustic and seismic excitation methods for buried containers
Authors: Sabatier James
Published: December 2020

Acoustic and seismic sources have been used to excite vibrations in buried containers. However, there have not been experimental comparisons of these source types to determine the target vibration excitation efficiency. Comparison of the acoustically and seismically induced vibration signals on the ground surface directly over and away from the buried container is a straightforward approach to quantify the efficiency. A finite element modeling [Muir et al., “Comparison of acoustic and seismic excitation, propagation, and scattering at an air-ground interface containing a mine-like inclusion,” J. Acousti. Soc.. Am. 135(1), 49–57 (2014)] of a buried target has quantified this efficiency by comparing calculated vibrational levels for acoustic and seismic sources before and after the “container” is put in place in the model. The modeling concludes the acoustic source is 10 dB greater than the seismic source. An experimental effort to compare the excitation efficiency of acoustic and seismic excitation techniques is reported in this paper. The sources are seismic and acoustic and include continuous wave and impulsive excitation at short and long ranges.
Speech planning impacts word-final consonant variation
Authors: Kilbourn-Ceron Oriana , Goldrick Matthew
Published: December 2020

We examine how constraints on advance planning in speech production impact word form variation. A /t/ can be produced as a flap only when it's followed by a vowel (e.g., in “atom” and “great exam”). Planning can influence this process by restricting the availability of the following vowel during planning of the /t/. We tested this by examining the reading aloud of adjectives with final /t/ followed by nouns varying in planning difficulty (from hard-to-retrieve low frequency to easily retrieved high frequency; e.g., “great airwave” versus “great exam”). The flap versus non-flap realization of the /t/ was quantified by the percentage of voicing from the offset of the vowel preceding the /t/ target to the onset of the vowel following the /t/. There was less voicing during this interval when the following noun was difficulty to retrieve. This provides new evidence that constraints on speech planning play a role in determining words' phonetic realization, above and beyond the lexical properties of the words themselves.
Ray methods and infrasound
Authors: Norris David
Published: December 2020

Infrasound is formally defined as sound at frequencies of 20 Hz and below. Because of low atmospheric absorption, infrasound canpropagate thousands of km or more with minimal attenuation. Ray methods are effective in characterizing long-range infrasound propagation, in particular for predicting acoustic paths and identifying dominant ducting mechanisms. In this talk, the assumptions, advantages, and disadvantages of infrasound ray modeling will be reviewed. Focus will be given to the effects of moving media, range-dependence, and horizontal refraction. Examples from special event studies will be shown to illustrate specific effects. The talk will conclude with the author's view of the modeling challenges facing the current infrasound research community moving forward.
Teaching musical acoustics with simple models and active learning
Authors: Neilsen Tracianne B. , Vongsawad Cameron T. , Onwubiko Stephen G.
Published: December 2020

When teaching musical acoustics to undergraduates, some have difficulty understanding how acoustical principles are related to music production. These difficulties are mitigated by using simple physical models and employing active learning activities. Three models are particularly helpful: mass-spring systems, string and tube resonances, and Helmholtz resonators. Students can gain hands-on experience with these models in both personal and guided laboratory experimentation. Examples of both types of experiments are provided to illustrate how they enable students to better understand the acoustics of musical instruments. These active learning activities highlight similarities and differences between the different families of musical instruments. The active learning activities are particularly impactful when students write about their experiences using proper acoustical terminology. The resulting understanding of acoustical principles enhances music education.
Laser Doppler multi-beam differential vibrometry
Authors: Aranchuk Vyacheslav , Aranchuk Ina , Carpenter Brian , Hickey Craig J.
Published: December 2020

A Laser Multi-Beam Differential Interferometric Sensor (LAMBDIS) for measuring vibration fields has been developed that alleviates one of the major issues of traditional laser Doppler vibrometers: effect on measurements by motion of the vibrometer itself. The LAMBDIS simultaneously measures Doppler shifts of light reflected from different points on the object surface illuminated with a linear array of laser beams. As a result, the LAMBDIS measures relative velocities between points on an object surface, while the Doppler shift caused by the sensor motion is approximately the same for all beams and is automatically subtracted from the measurements. This allows measurements of vibration fields of objects with high sensitivity from a moving platform. Scanning the linear array of laser beams in the transverse direction provides a two-dimensional vibration image of the surface. Performance of the sensor for ground vibration sensing for acoustic detection of buried objects has been investigated in the laboratory and field experiments. The sensor proved effective at detecting buried objects from a moving vehicle. [Work supported by the Office of Naval Research.]
The use of optical methods for measuring weak acoustic shock waves in homogeneous air and close to reflecting boundaries
Authors: Karzova Maria M. , Yuldashev Petr V. , Ollivier Sebastien , Khokhlova Vera , Blanc-Benon Philippe
Published: December 2020

Measuring blast waves in laboratory-scale experiments using acoustical methods is a challenge. Optical methods provide an attractive possibility for recording pressure signatures of weak acoustic shocks. In this presentation, recent experiments for reconstructing pressure waveforms of spark-generated spherically divergent blast waves (1.8 kPa amplitude and 50 μs duration at 15 cm distance from the source) both in homogeneous air and close to reflecting surfaces are overviewed. Three methods were employed: shadowgraphy, schlieren, and interferometry. It was shown that shadowgraphy method allowed for measuring shock thickness and its amplitude. Schlieren technique provided reconstruction of the pressure waveforms in homogeneous air. In the reconstruction process the front geometry was assumed to be spherical or cylindrical. The exposure time of the high-speed camera was a limiting factor for the time resolution. Mach-Zehnder interferometer method was the most relevant for laboratory-scale measurements. The method reached 0.4 μs of time resolution, which was more than 6 times higher than that of 1/8-in condenser microphones. Moreover, the Mach-Zehnder interferometry allowed quantitative reconstruction of the pressure waveform without additional calibrations. The method was successfully applied for measuring waveforms in homogeneous air and reflected waves from rigid smooth and rough surfaces. [Work supported by ANR-10-LABX-0060/ANR-16-IDEX-0005.]
Detection of modulated rippled noise
Authors: Sheft Stanley , Shafiro Valeriy
Published: December 2020

Bill Yost's study of modulation detection interference (MDI) was in part motivated by his earlier work with temporally modulated rippled noise (RN) which indicated difficulty monitoring a single auditory channel in the presence of cross-channel modulation. The present work further evaluated parameters in the processing of dynamic spectral profiles. In the first experiment, gain in RN generation was sinusoidally modulated. If the gain sign remained unchanged during modulation, modulation resulted in a roughly constant increment in ripple-detection thresholds across change in modulation rate from 2 to 128 Hz. However, cross-sign gain modulation led to a lowpass result with thresholds increasing with modulation rate. A similar lowpass result was obtained in the second ripple-detection experiment in which delay in RN generation was modulated. The third experiment measured thresholds for detecting delay modulation. Thresholds, in terms of Weber ratios, rose with increasing modulation rate from 2 to 8 Hz. Across experiments, the lowpass results contrast with MDI in which interference decreases with increasing modulation rate. With dynamic spectral profiles, there is significant envelope modulation of individual auditory channels due to stimulus frequency excursions. Results suggest a limitation imposed by cross-channel envelope incoherence in utilizing this envelope modulation.
Theoretical and experimental investigation of the transmission/reflection pressure fields of labyrinthine unit cells
Authors: Azbaid El Ouahabi Abdelhalim , Memoli Gianluca
Published: December 2020

Labyrinthine unit cells have been around for many years and have been central to the design of many metamaterial solutions. However, the literature does not present a reproducible analytical model to predict their behaviour both in transmission and reflection, thus limiting design optimisation in terms of bandwidth of operation and space occupied. In this work, we present an analytical model based on the transfer matrix method for the phase shift of the transmission/reflection labyrinthine unit cells. we validate our model using Finite Element Method (FEM) simulations—using a commercial software—and experimental measurements. We discuss the limitations of our approach and the perspectives opened by it.
Information about talker dialect is available in high-frequency region
Authors: Fox Robert A. , Jacewicz Ewa
Published: December 2020

Given that almost all cues to speech intelligibility are contained within the low-frequency region, high-pass filtering has not been used in speech perception research as often as low-pass filtering. We provide evidence from high-pass filtered speech that information about talker dialect is available in the high-frequency region even in the absence of intelligibility cues. Setting the upper frequency limit at 11 kHz, sentences edited out of spontaneous conversations of 20 talkers from Ohio and 20 from North Carolina were high-pass filtered with frequency cut-offs varying from 0.7 to 5.56 kHz and presented to listeners from Ohio. Results showed that listeners were still sensitive to differences between the two dialects at the two highest cut-offs, 3.32 kHz and 5.56 kHz, and dialect identification was mediated by talker sex. Also, identification of talker sex was affected by dialect, with Ohio variety providing more cues to talker sex at 3.32 kHz and the variety in North Carolina at 5.56 kHz. Speech intelligibility was reduced above 3 kHz, and Ohio speakers were more intelligible overall. Irrespective of the intelligibility loss, the results suggest that residual dialect cues are still distributed in the high frequency region, and are preserved differently in male and female voices.
Interpreting the environmental information embodied in universal adaptive beamformers
Authors: Buck John R. , Wage Kathleen E.
Published: December 2020

Practical adaptive beamformers often include regularization parameters to mitigate the impact of limited training data. These parameters may include the dominant subspace dimension for projection beamformers and the averaging window for the sample covariance matrix. Choosing the optimal value for these regularization parameters requires environmental knowledge not available to the algorithm in real time. Universal adaptive beamformers (UABFs) avoid the need for this knowledge. UABF outputs are a performance-weighted blend of the outputs of a competing family of beamformers. These blend weights embody operationalized knowledge about the array's environment. This environmental knowledge may be explicitly or implicitly represented, depending on the underlying beamformers within the universal framework. Previously proposed UABF implementations were universal over the dominant subspace dimension [Buck et al., ASA (2018)] and the sample covariance matrix averaging window [Buck, ASA (2019)]. The former explicitly provides information about the number of interferers in the environment, while the latter implicitly captures information about the bearing rates of the interferers. Data analysis from an ocean acoustic experiment will demonstrate an example of the environmental information available from the blend weights. [Work funded by ONR 321US.]
Performance weighted blended spectral estimation on experimental seaglider data
Authors: Tucker Jeff , Wage Kathleen E. , Van Uffelen Lora
Published: December 2020

A common problem in underwater acoustics is the non-parametric estimation of a power spectrum from time series data with windowed Fourier transforms. If characteristics of the environment such as signal to noise ratio or the frequency of loud line components are known then an appropriate window can be identified. When estimation is performed without a priori knowledge of the environment, an analyst often uses an ensemble of different windowed Fourier transforms and synthesizes the results. When no analyst is available this process must be automated. The performance weighted blended~(PWB) spectrum estimator automates the work of an analyst by weighting each estimator in an ensemble based on its performance and summing them to create a new estimator that performs as well or better than each estimator in the ensemble regardless of the characteristics of the environment [Tucker et al., IEEE UASP Workshop (2019)]. This talk summarizes the PWB estimator, and compares it to existing estimators when applied to passive acoustic data collected from a hydrophone mounted on a Seaglider autonomous underwater vehicle. Additionally, the talk presents modifications to the original PWB estimator that offer improved robustness in the presence of loud transient signals, e.g., noise from glider hardware. [Work supported by ONR.]
Vector sensor beam steering for underwater acoustic communications
Authors: Bozzi Fabricio A. , Jesus Sérgio M.
Published: December 2020

Acoustic Vector Sensors(VS) have been widely used for direction-of-arrival estimation in the past, while the employment of VS for underwater communications is a recent topic. Due to its compact size, VS may be used as a receiver in applications such as on board of Unmanned Underwater Vehicles (UUV), providing higher maneuverability and operational capabilities. Thus, in this study, the communication performance of a VS beam-steering technique is quantified. The performance analysis is made comparing the VS beam-steering with the versus time-reversal method in a shallow water simulation. The underwater channel is given by the seismo-acoustic propagation model, OASES. A Phase Shift Keying(PSK) modulation is adopted and the receiver includes a Decision Feedback Equalizer. An individual analysis of horizontal and vertical particle velocity is made to show the steering effects in the error performance. Moreover, as the steering angle is range-dependent, a comparison between methods is performed varying the range. The result indicates that the optimum steering angle, which brings less error, may not be related to the source direction. Furthermore, the proposed receiver shows the outperformance comparing to the time-reversal in both SNR and range, demonstrating the spatial filter advantage provided by this co-located sensor.
Peaks between peaks: Comparative intra-ear correlations in spontaneous otoacoustic emissions
Authors: Bergevin Christopher , Afify Tarnem , Whiley Rebecca
Published: December 2020

Spontaneous otoacoustic emissions (SOAEs) are a key facet of modern models of inner ear biomechanics, as the phenomenon provides crucial insight into the notion of the “active ear.” Manifesting as an idiosyncratic array of spectral peaks unique to a given ear, individual SOAE peaks have nonstationary properties (e.g., amplitude and frequency modulations). Further, it has been demonstrated that interpeak relations between these “AM” and “FM” properties can be correlated, indicative of coupling of the underlying generation mechanisms. This study takes a comparative approach to characterizing these correlations in a wide variety of species exhibiting SOAEs (humans, birds, lizards) despite relatively disparate inner ear morphologies. Initial results are consistent with previous reports (e.g., van Dijk and Wit, 1990, 1998) in that SOAE interpeak correlations for a given ear are themselves idiosyncratic: Sometimes peaks (adjacent or not) exhibit correlated (positive or negative) AM and/or FM fluctuations with delays up to the order of milliseconds (typically longer for humans, shorter for lizards), while sometimes no correlation is observed. We explore implications for how such may constrain models treating the inner ear as a spatially distributed tonotopic system (e.g., various biophysical roles for coupling).
Transcranial cavitation localization by time difference of arrival algorithm using four sensors
Authors: Hu Zhongtao , Xu Lu , Chien Chih-Yen , Yang Yaoheng , Gong Yan , Ye Dezhuang , Pacia Christopher P. , Chen Hong
Published: December 2020

Cavitation is widely existing in focused ultrasound (FUS)-mediated therapies in the brain, such as FUS in combination with microbubble-induced blood-brain barrier disruption, nonthermal ablation, as well as transcranial histotripsy therapy. Accurately knowing the 3-D location of cavitation in real time can improve the treatment targeting accuracy and avoid off-target tissue damage. However, the skull induces strong phase and amplitude aberration to the cavitation signals and presents a significant challenge to the transcranial cavitation localization. Existing techniques for 3-D cavitation localization use hemispherical multi-element arrays combined with passive beamforming and adaptive skull-specific correction algorithm. However, these techniques require expensive equipment and treatment planning. Their time-consuming computations limit applications in real-time cavitation monitoring, which is critically needed to ensure the safety and efficacy of the FUS treatment. The object of this study was to investigate the feasibility of using a four-sensor network to transcranially locate the cavitation source in 3-D by time difference of arrival algorithm. The positional error of transcranial cavitation localization with the human skull along x, y, and z axes were 1.7 ± 1.2 mm, 1.6 ± 1.7 mm, and 4.1 ± 1.5 mm, respectively. For comparison, the positional error of without the human skull were 1.2 ± 1.8 mm, 0.9 ± 1.6 mm, and 3.1 ± 2.3 mm, respectively.
A parametric study of long-range atmospheric sound propagation using Bellhop Ray-tracing Model
Authors: Hussain Hammad , Dutilleux Guillaume
Published: December 2020

In the context of research on the measurement of long-range attenuation of noise from terrestrial sound sources, a parametric study of atmospheric sound propagation channel characteristics as a function of source height, ground characteristics and meteorological conditions is presented. The study relies on ray tracing. The Bellhop ray-tracing model which is well known in underwater acoustics has been used here. In this paper, the accuracy of Bellhop's predictions in the atmosphere is first addressed by comparison with published benchmarks cases by Attenborough et al and results from Salomon's ray model. No significant discrepancy was noticed with respect to these references. The second part of the paper presents a parametric study for source heights ranging from 0.05 m to 200 m, a grid of receivers at ranges between 200m and 2 km from the source and between 2 and 50 m height. A homogeneous flat absorbing ground described by a complex reflection factor is assumed. For the atmospheric conditions, a subset of the WiSi classification was considered. The results are analyzed from the point of view of the receiver and discussed in terms of attenuation, number of arrivals and number of reflections from the ground.
Design, construction, and analysis of ukuleles as a method for teaching on the acoustic properties of stringed instruments
Authors: Gangemi Nicholas , Dutz Nicholas , Vignola Amelia , Regmi Sarthak , Turo Diego , Vignola Joseph
Published: December 2020

This presentation will discuss an undergraduate course taught at Catholic University where the primary learning objective was for the students to understand how the design characteristics of a stringed instrument effects its acoustic properties. Previous student-led design projects have researched the acoustic properties of stringed instruments, notably guitars and five-string banjos, but no formal course has ever been offered on the subject. Further, all previous investigations utilized commercially available instruments as the test subjects, and thus, were limited in the design characteristics available to test. The course combined hands-on education about the construction of ukuleles, with subsequent measurement and analysis of the acoustic properties. Ukuleles were chosen as the test subject due to their simplicity compared to other stringed instruments, which allowed students with various levels of shop experience to participate in relevant aspects of lutherie. The ukuleles featured both conventional and non-conventional design characteristics, and were constructed with both traditional and non-traditional methods. Upon completion of the course, the students constructed nine different ukuleles, collected a large set of acoustic data, and completed preliminary analyses of the various instruments. Interest in the subject has persisted beyond the course, and several research projects on the subject have resulted.
Perspectives from the honoree: Serendipity, gratitude, and an exiguity of prognostication
Authors: Berger Elliott H.
Published: December 2020

As this is being written, I am excited, honored, and humbled but the mere notion that a session has been planned in my honor, even though the full implications of the title “…responding to external stimuli” still escapes me. I am presuming all will be revealed. The opportunity to close out the show, to have the last word as it were, was also a surprising and an unexpected gift. My goal will be to make it worth the audience's while. I will briefly review the accomplishments of which I am most proud, and then emphasize the importance of serendipity in our lives, especially mine, as when I stumbled across an obscure 1/6-page add in the back of Physics Today that led me to a career associated with the ground-breaking yellow foam earplug. The gratitude I have for fabulous mentors in my life such as Larry Royster, Ross Gardner Jr., Don Gasaway, and Mead Killion, will be expressed. Finally, I may share a few brief observations about what might come next in the fields of hearing protection and hearing conservation.
Soundscape: How do we perceive vehicle noise under the exceptional circumstances due the pandemic? Impact of COVID-19 upon the understanding of our acoustic environments
Authors: Schulte-Fortkamp Brigitte
Published: December 2020

New findings about the possible decrease in experienced daily loudness are vastly less important than recognition about the meaning of the sounds in our new sonic reality. The recent pandemic has changed daily life in many respects. These changes have caused significant changes in soundscapes also in regard to its acoustic parameters and as well in their perception. The application of the Soundscape standard ISO 12913 1-3 will guide the understanding of the recent developments concerning the new living situations. This paper will discuss the ISO standard and the potentials of its use in regard to electric vehicles in these exceptional circumstances.
Annoyance at the point of emission versus immission for impulsive noises at train passings
Authors: Huth Christine , Forstreuter Melissa , Arlt Robert , Liepert Manfred
Published: December 2020

Impulsive components of the noise of passing vehicles can cause increased annoyance for the nearby inhabitants. For example, the periodic excitation of a damaged wheel creates a noise with a clearly noticeable fluctuation strength. This leads—in addition to the sound pressure level, which is also raised by the impulsive component—to a significant annoyance of the residents. Usually, such signals are recorded in the vicinity of the point of emission (in the distance of 7.5 m). The scope of the present study was to investigate the question to what extent the annoyance of the residents at the point of immission can be predicted by using these recorded signals. For this purpose, by means of subjective evaluations the annoyance of original signals at the point of immission was compared with that of recordings at the point of emission reduced in accordance with the distance law.
Towards real-time muscle fatigue and recovery markers using a wearable continuous wave Doppler ultrasound system
Authors: Majdi Joseph , Chitnis Parag V. , Sikdar Siddhartha
Published: December 2020

Functional electrical stimulation (FES) is commonly used in physical rehabilitation, bypassing the central nervous system to activate motor neurons directly. However, the unnatural muscle recruitment pattern induced by FES causes rapid muscle fatigue, greatly reducing the muscle's ability to generate force. Currently there exists no reliable, real time indicator for FES-induced muscle fatigue. We believe that signs of muscle fatigue can be inferred from medical ultrasound. Previously we investigated tissue Doppler imaging (TDI) to study muscle physiology associated with muscle potentiation and fatigue. Here, we expand on that research using continuous wave (CW) Doppler ultrasound to create a wearable, low power muscle fatigue monitor. We are investigating this system to work with a hybrid FES exoskeleton designed to use the patient's own muscles with FES with the added stability of an exoskeleton. CW ultrasound indicated that the duration of muscle recruitment decreased from 129.0 ms to 51.7 ms for the same FES as the muscle fatigued. Further, we showed that muscle twitch duration and velocity correlate with twitch force, a marker of fatigue recovery, using TDI and CW. These fatigue and recovery measures can be used to inform the exoskeleton controller to coordinate FES and electric motors for producing gait.
Shape optimization of a compression driver phase plug taking visco-thermal losses into account
Authors: Berggren Martin , Bernland Anders , Massing André , Noreland Daniel , Wadbro Eddie
Published: December 2020

The compression driver, used to feed midrange horns, consists of a compression chamber whose outlets are connected to the horn throat through a phase plug. The main challenge in the design of the phase plug is to avoid resonance and interference phenomena. The complexity of these phenomena makes it difficult to accomplish this design task manually. Therefore, we employ an algorithmic technique that combines numerical solutions of the governing equations with a gradient-based optimization algorithm that almost arbitrarily can deform the walls of the phase plug. A particular modeling challenge here is that visco–thermal losses cannot be ignored, due to the presence of narrow chambers and slits in the driver. Fortunately, a recent accurate but computationally inexpensive boundary-layer model is applicable and is here successfully used within the optimization loop. We use this model together with the so-called Cut Finite Element technique to avoid mesh changes when the geometry is modified by the optimization algorithm. Applying these techniques, the algorithm was able to successfully design the shape of a set of radially-directed phase plugs so that the final frequency response closely matches an ideal response, that is, one that is obtained by a lumped circuit model, ignoring wave effects.
Photoacoustic imaging demonstration
Authors: Burge Leah E. , Korman Murray S.
Published: December 2020

Experiments [T. J. Allen and P. C. Beard, “High power visible light emitting diodes as pulsed excitation sources for biomedical photoacoustics,” Biomed. Opt. Express 7(4), 1260–1270 (2016)] describe the use of a visible light-emitting diode (LED) as an alternative to using a Q-switched Nd:YAG laser as a photoacoustic excitation (1 mJ pulse) source for below-the-surface vascular imaging. They describe the feasibility of using a low-cost LED, overdriven by a factor of 10 in current, with short pulses ∼200 ns operating at a 0.01% duty cycle to achieve ∼10 μJ in an imaging experiment involving hemoglobin absorption (wavelength of 623 nm). A version of the experiment is demonstrated where an SST-90R LED (λ = 620 nm, 18 A maximum CW current) is driven from a home-made MOSFET pulsed driver, capable of providing pulses up to 50 A. Our demonstration of photoacoustic tomography involves a ∼1cm diam LED beam illuminating three closely-spaced vertical 1.4 mm tubes filled with blood (35% haematocrit), mounted in an open acrylic water tank. An immersion transducer (3.5 MHz, cylindrically focused PZT with 60 dB gain) detects time-averaged photoacoustic signals versus rotation angle. Then back-projection imaging can construct a two-dimensional image.
Phase spectral characteristics of room transfer function and coherent length in reverberation sound field
Authors: Tohyama Mikio , Takahashi Yoshinori
Published: December 2020

The authors had studied multi-degree-of-freedom vibration system and room transfer function in a reverberant sound field focusing on zeros in the transfer function and its phase spectral characteristics, under the leadership of Professor R. H. Lyon for 20 years since 1988. Since 2006, room acoustics and wave propagation in rooms have been investigated with an inspiration from zero-drift model (the movement of zeros on the complex frequency plane) on the sound field close to a source, which was one of the most important Lyon's hypotheses. In this report, the behavior in the distribution of minimum-phase zeros is visualized by means of the narrow-frequency-band analysis for phase-frequency-characteristics on the minimum-phase component of impulse responses measured in a reverberation room. Additionally, it demonstrates that the inclination of the linear regression line for the phase-frequency-characteristics indicates “propagation phase” conjectured by Lyon with the use of the zero-drift model, namely, “phase change” proportional to the distance between a sound source and a sound receiving point. Furthermore, it shows that the range where the propagation phase is observed in the phase-frequency-characteristics agrees with the coherent length where sound waves propagate as spherical waves, which was inferred by P. M. Morse and R. H. Bolt (1944).
Analysis of acoustic radiation from instability waves within an off-design supersonic jet flow using combined theory and large-eddy simulation
Authors: Cheng Jianhui , Goldschmidt James D , Shen Weiqi , Lawrence Ukeiley , Miller Steven A.
Published: December 2020

The impact of large-scale turbulent structures on the aerodynamic flow-field and far-field radiated noise is investigated through analysis of an over-expanded supersonic jet. The jet operating conditions are Mj = 1.3 and Reynolds number 1.6 × 106. The Kirchhoff surface (KS) method is used to predict radiated noise based on large-eddy simulation (LES) and applied to calibrate amplitudes of an instability wave model. The acoustic pressure time history in the near- and far-field are constructed with the instability wave model. Predictions are validated with experiment and compare favorably. Cross-correlation and cross-spectral analysis shows that the noise from instability waves is highly correlated the upstream near-field and downstream far-field radiation directions. However, the radiated instability noise in the upstream direction is dominated by fine-scale noise. Results show that it is possible to design a control system for large-scale structure noise based on upstream control if the instability noise can be extracted.
Lateralization asymmetry in right/left ears of elderly individuals with respect to various sound pressure levels
Authors: Morita Kazumoto , Osawa Tsukuru , Toi Takeshi
Published: December 2020

Authors have previously reported that elderly individuals have asymmetrical right and left ear performance when they horizontally lateralize a 1kHz pure tone with Interaural Time Differences (ITDs). In the previous experiment, the Sound Pressure Level (SPL) was set to 60.0 dB(A), but in the present experiment, conditions were set every 1.5 dB(A) from 54.0dB(A) to 66.0 dB(A) in order to investigate the effect of SPLs. For ITDs, 8 conditions were set to lead the right or left ear and those were 0.2, 0.4, 0.6, and 0.8 ms, respectively. The frequencies of the sounds were two types: 1 kHz and 0.5 + 2 kHz. As a result, for a 1 kHz pure tone, the elderly individuals have asymmetry in right and left ear performance. As the ITD increases, it is more likely that the sound leading to the right ear is referred to as left. The lower the SPL, the more confusion exists between the right and left. Even in the elderly, confusion is rare for a sound of 0.5 + 2 kHz. Young individuals rarely have confusion between the right and left ears for all conditions.
Lateralization of interaurally delayed stimuli with identical amplitude spectra but different temporal envelopes
Authors: Encke Jörg , Dietz Mathias
Published: December 2020

Interaurally delaying a 500 Hz tone by 1.5 ms is identical to advancing it 0.5 ms. Presented over headphones, humans perceive such a tone lateralized toward the side of the nominal lag. Any stimulus other than pure tones has more than one frequency component, disambiguating the true delay. When increasing the bandwidth of 1.5 ms delayed narrowband noise, the percept indeed changes from the nominal lag to the lead. However, little has been published about the stimulus- and subject specific factors that influence this changeover bandwidth. The historically first suggested mechanism requires a neural extraction of the cross-correlation function up to at least ±1.5 ms and compares its peak positions across frequency bands. Up to date this so-called “straightness” extraction is the standard model approach despite a lack of support from mammalian brainstem physiology and human brain imaging. Here, this concept is challenged by its strong suit: psychophysics. Stimuli with identical amplitude spectra but differently pronounced temporal envelopes are shown to have significantly different crossover bandwidths, despite identical straightness. The data reveal that within-channel envelope disparities—the only temporal cue at high frequencies—are also exploited at 500 Hz. The finding may help resolving model contradictions between perception and physiology.