bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrasound-targeted microbubble destruction (UTMD)—Novel applications for microRNA delivery
Authors: Leong-Poi Howard
Published: April 2019

Ultrasound-targeted microbubble destruction (UTMD) is a non-invasive technique for gene delivery, utilizing high power ultrasound and nucleic acid-bearing microbubbles. UTMD has been used in a variety of in vivo applications, including cardiac and skeletal muscle, kidney, liver, cerebral and even lung, and have been studied using many gene vectors, including plasmid, viral and small interfering RNA. The focus of gene therapy has now shifted towards small non-coding RNAs, including microRNAs (miRNA). These non-coding RNAs are important transcriptional and post-transcriptional inhibitors of gene expression that regulate the translational output of target messenger RNAs. MicroRNAs have been shown to participate in a multitude of cellular process, and their dysregulation may play an important pathophysiologic role in many different human pathologies. Coupled with their ability to specifically target particular cellular pathways, makes the possibility of exploiting miRNAs to develop therapeutic strategies extremely attractive. This presentation will focus specifically on several miRNAs with UTMD applications in (1) chronic ischemic peripheral arterial disease, (2) ischemia-reperfusion injury, and (3) abdominal aortic aneurysms (AAA). For each application, we will discuss selection of miRNA, aspects of tissue targeting in vivo, enhancement of therapeutic effect and potential for clinical translation.
Histotripsy-enhanced thrombolysis
Authors: Bader Kenneth B. , Hendley Samuel A. , Bollen Viktor , Maxwell Adam D. , Haworth Kevin J. , Holland Christy K.
Published: April 2019

Deep vein thrombosis (DVT) is a major public health problem, affecting 600,000 Americans annually with a healthcare cost of $10 billion. Standard interventional techniques are not effective for the chronic thrombus components present in 27% to 43% of DVT cases. Histotripsy is a focused ultrasound therapy that employs the mechanical action of bubble clouds to ablate tissue and induce vigorous fluid mixing. We have demonstrated synergy between histotripsy and the thrombolytic recombinant tissue plasminogen activator (rt-PA) for dissolution of retracted venous clots in vitro. Here, the role of histotripsy-induced bubble activity in rt-PA clot dissolution will be discussed. The rt-PA thrombolytic efficacy of histotripsy pulses that nucleate bubble activity either via (1) shock wave scattering or (2) exceeding the intrinsic cavitation threshold of the clot will be presented. The impact of each histotripsy type on the formed elements that comprise the clot will be described, as well as the likelihood of containing mechanical activity within the target zone. Finally, the utility of passive cavitation imaging to quantify the bubble activity necessary for liquefaction of tissue-mimicking phantoms representative of acute and chronic pathologies will be presented.
The University of New Orleans ocean acoustics program at the Stennis Space Center, Mississippi
Authors: Chin-Bing Stanley A.
Published: April 2019

In the late 1970's two US Navy ocean R&D organizations were formed and located at the Stennis Space Center (SSC), Mississippi, located approximately 50 miles East of the University of New Orleans (UNO). These two organizations employed nearly 1500 scientists, engineers, and technicians. Many of those with a Bachelor degree in physics, oceanography, or engineering desired advanced training in acoustics and signal processing. In 1982, George E. Ioup took the initiative to have UNO develop and teach acoustic courses on-site at the SSC. In the following 33 years, I developed 11 different graduate level courses in acoustics and taught them multiple times at the SSC. It was possible to take all the necessary courses needed for the Masters and PhD degrees on-site, while maintaining full-time employment. Several dozen Navy scientists received advanced degrees in physics with a specialty in acoustics from UNO. Many more received specific training in acoustics that enhanced their professional careers. This presentation will highlight my contribution to the UNO program at the SSC, and discuss how I incorporated my own research in ocean acoustic propagation and scattering into the many acoustic courses that I taught.
Writing strategies for students and their mentors: From the perspective of a recent student
Authors: Whiteford Kelly L.
Published: April 2019

Writing an empirical paper can be a daunting process, particularly for students writing their first manuscript. This presentation will provide advice for helping students develop a structured and goal-oriented writing routine to aid in the publishing process. First, the mentor can help foster motivation to write by guiding the student to pursue research that is tethered to the student’s intrinsic interests but still within the domain of the mentor’s expertise. Second, writing goals need to be prioritized by the student in a specific, achievable, and time-bound manner. This prioritization can occur through creating a structured, weekly outline of writing-related goals, either with guidance from the mentor or through a peer support group. Setting aside regular, protected writing time can help form a habit out of writing and ensure it does not become pushed aside for other priorities. Lastly, -timely, thorough, and constructive feedback from the mentor can speed up the writing process while conveying to the student that their work is a priority of the mentor.
Investigations into the acoustics of the mandolin
Authors: Tufte Steve , Hunt Samuel , Hegarty Gerrick
Published: April 2019

The mandolin is a descendent of the lute with a long history starting in 18th century Italy. This talk will give a brief history of the mandolin culminating in the modern flat-back mandolins used in bluegrass music. After a summary of previous research into its acoustics, we will describe our current research. This includes the use of Electronic Speckle Pattern Interferomentry (ESPI) to study the low-modes of the front and back plates and studies of the driving point impedance at the bridge. The mandolin has four courses of doubled strings tuned in unison. Inspired by Weinreich’s seminal study of piano strings, we explore the coupling of the strings’ motions to each other through their attachment to the vibrating bridge. By using a macro lens on a high-speed camera, we are able to study these motions in exquisite detail. We observe clear evidence of coupling including the exchange of energy between the vertical and horizontal motions of each string and correlations in the phases of their motions. We interpret the experimental results in the context of a theoretical model. [Work supported by the National Science Foundation under Grant No. 1707978.]
Evaluating manufacturing environment soundscapes
Authors: Puckett Brian J. , Ryherd Erica E.
Published: April 2019

This work presents an investigation into the soundscape of a large, industrial manufacturing plant in Lincoln, Nebraska, including exploration of the noise reduction performance of sound enclosures. Occupational noise-induced hearing loss is among the most common nonfatal work-related injuries and illnesses in the U.S., and most efforts to reduce this exist as limited noise exposure times and mandatory use of hearing protection devices. This research aims to develop knowledge of factory soundscapes and explore acoustical strategies to reduce noise near the source. The factory in this study uses two distinct types of sound enclosures on site: rigid box-style enclosures and resilient curtain-style enclosures. Using state-of-the-art technology, it was possible to better understand contributions of single noise sources to the complex, overall soundscape and evaluate some detailed acoustical characteristics of the noise. The measured data are compared with subjective assessment of company employees using methods described in Part 2 of the Soundscape Standard (ISO/TS 12913-2). Results presented include a noise reduction comparison of the two types of enclosures, a relationship between noise reduction and source-enclosure proximity, and a comparison between measurements and survey data.
Nonlinear acoustic crack detection in thermoelectric wafers
Authors: Greenhall John , Graham Alan , Pantea Cristian
Published: April 2019

We present an acoustic technique for noninvasive crack detection in small (approximately 30.0 ×18.0 × 0.5 mm) thermoelectric wafers. The technique is based on exciting the wafers with a low-frequency signal that drives the crack to open and close periodically, and a high-frequency signal that is permitted to propagate through the closed crack and prohibited from propagating through the open crack. Interaction between the low- and high-frequency signals and the crack leads to generation of acoustic nonlinearities in the wafer. In contrast to existing acoustic crack detection techniques we utilize standing waves within the wafers to facilitate simultaneous crack detection throughout the wafer, we do not require uniform dimensions and material properties between wafers, and we do not affix the transducer to the wafers to avoid damaging the wafers. We present a mathematical model of the acoustic nonlinearity generation process and develop a procedure for identifying cracked wafers. We implement this technique experimentally and correctly identify cracked and crack-free wafers with total error in low single digits. This acoustic crack detection technique finds application in manufacturing of thermoelectric wafer and other wafers, where identifying cracks early in the manufacturing process results in significant time and cost savings.
Slow-dynamical nonlinearity in a glass bead pack probed with diffuse ultrasound and coda-wave interferometry
Authors: Weaver Richard , Yoritomo John Y. , Popovics John , Bittner James
Published: April 2019

Low amplitude diffuse coda ultrasound probe signals received through unconsolidated glass bead packs under static vertical loads are used to measure the bead pack's slow dynamics, in which the speed of low amplitude probe waves varies slowly with time long after loading. Coda-wave interferometry reveals tiny stretches in the waveform, with precision of parts in 105. These stretches are ascribed to decreased contact stiffnesses or decreased sound speeds. The coda-wave stretch is observed to be sensitive to low frequency conditionings at strains of order 10-5. Such conditionings include taps on the sides, low frequency harmonic vibrations and impulses on top, and step changes in vertical load. Typical behavior after the conditioning is an initial loss of stiffness followed by a slow healing that proceeds with the logarithm of time. The initial loss of stiffness and its slow dynamic healing are investigated for sensitivity to sundry parameters.
Challenging standard practices in adaptive psychophysics
Authors: Hoover Eric C. , Gallun Frederick J. , Eddins David A.
Published: April 2019

One of the most cited manuscripts in behavioral hearing research is Levitt [J. Acoust. Soc. Am. 49, 467–477. (1971)]; it is typically the only reference cited in the procedures section of studies reporting thresholds obtained via adaptive tracking. This is problematic because Levitt (1971) informs only one among many parameters used in threshold estimation, and the relationship between Levitt’s transformed up-down method and the proportion correct targeted by the procedure is commonly disrupted by the selection of the remaining parameters [Vis. Res. 38, 1861–1881. (1998)]. We explored the evidence supporting standard practices and found that step size, stopping criterion, and threshold estimation from track data have limited theoretical motivation and can introduce systematic bias and error into threshold estimates as shown in behavioral and simulation studies. As a result, we propose an approach to developing and describing methods for behavioral threshold estimation that offer improved efficiency, reliability, reproducibility, and are no less consistent with Levitt (1971). [Work supported by NIH NIDCD DC015051.]
Randomness in periodic metamaterials
Authors: Esfahlani Hussein , Alu Andrea
Published: April 2019

The most straightforward way to design artificial structures is to use periodicity and leverage its potential mathematical and physical consequences to our favor. However, strict periodicity, which is usually employed in designing artificial materials, is not practically feasible and most often some degrees of randomness are introduced in the fabrication process, which degrade the performance. In this presentation, using the Furstenberg theory on the product of random matrices and Monte Carlo simulations we explore the effect of randomness in the transmission performance of periodic structures designed to realize density-near-zero (DNZ) metamaterials. We show that DNZ propagation is very sensitive to randomness, and we unravel the physics behind this sensitivity with analytical theory and full-wave simulations.
A comparison study between topological insulators based on valley Hall and quantum spin Hall effects
Authors: Deng Yuanchen , Jing Yun
Published: April 2019

Over the past few years, the rapid development in the fields of condensed matter physics, electronic and photonic systems have inspired the design and experimental demonstration of various acoustic topological insulators. Among these, the topologically protected one-way propagation is a phenomenon that is gaining increased attention. Pseudospin states, which is the analogue of the Quantum Spin Hall Effect from electronic systems, has been proven to enable topological edge states in acoustics. Similarly, Valley Hall (VH) effect is also observed in acoustic systems and provides a pair of valley vortex states with opposite chirality. These valley vortex states can similarly form topologically protected edge states and in turn realize robust one-way propagation. However, the differences in the physics behind these acoustic systems give rise to distinct features such as angle selection and immunization level to various types of defects. In this article, the comparison between topological insulators (TI) and valley hall topological insulators (VHTI) address the difference and similarities in several aspects. Both of them have topologically protected bandgaps and thus the robust one-way propagation. For the maximum transmission incident angle and defect immunization, however, VH topological waveguide and TI waveguide show different characteristics.
Speech perception in children with reading disabilities: Phonetic perception is the problem
Authors: Wu Yashuo , Lu Jie , Toscano Joseph C. , Johnson Cynthia , Allen Jont b.
Published: April 2019

Reading disability (RD) is widely accepted as a key obstacle in the development of literacy. Studies show that 15–20% of grade-school students are RD. Many quit high-school and go to jail. We shall show that RD for 8–12 yrs is related to inadequate phonetic identification ability, rooted in pre-school language development. We used two tests (10 thousand responses/child): (1) A 3-interval forced choice procedure (Syllable Confusion Oddball Task: SCO). (2) A single CV/VC presentation task with oral response, to label CV/VC phones (Nonsense Syllable Confusion Matrix: NSCM). The experimental results showed that for the SCO task the 10 RD cohort had, on average 5 times the error compared to the 6 RC reading control (RC) cohort. The errors were highly idiosyncratic, analyzed by logit. (1) RDs have significant speech perception problems, despite normal pure-tone hearing and language ability. (2) When comparing the SCO and NSCM results, our findings are consistent with a reduced ability to label CV/VC sounds presented in random temporal order. This seems consistent with phone memory dysfunction. (3) These conclusions are at odds with previous studies finding no indication of phone identification impairment.
Preschoolers initiate more conversations than their parents
Authors: VanDam Mark , Campanella Sarah , Wolfenstein Kiley , De Palma Paul , Olds Daniel
Published: April 2019

Children develop, learn, and refine the complex rules of how to have a conversation beginning in their preschool years. Recent work on conversational exchanges and language usage within families has shown differences (and in some cases, similarities) in how mothers, fathers, girls, and boys interact and converse with each other. It has been suggested that mothers contribute more child-oriented and child-driven exchanges, fathers contribute more formal language that includes problem-solving and linguistic manipulation, girls seek to maintain relationships, and boys seek to establish dominance and attract or maintain and audience. These factors may influence the roles each interlocutor plays in a communicative exchange. One aspect of verbal interaction is who initiates a conversational exchange. This study examined 134 daylong audio recordings using automated speech processing techniques to estimate the frequency of conversation initiation for mothers, fathers, girls, and boys. We found that children initiate conversations most frequently, followed by mothers, followed by fathers. We found no rate difference between girls and boys. Results are consistent with the Bridge Hypothesis or Apprenticeship Model in which interlocutors are motivated in part by their social role, in this case by the social modeling parents demonstrate for their children.
Syllable production in hard-of-hearing preschoolers
Authors: VanDam Mark , Wolfenstein Kiley , Campanella Sarah , Olds Daniel , De Palma Paul
Published: April 2019

Expressive language in preschoolers has been shown to be positively related to later language development, although not all studies have shown robust effects. Most studies that consider sex have shown that girls develop expressive language earlier than boys. It has also been widely demonstrated that children with a variety of speech-, language-, and hearing-related disorders show deficits in expressive language skills. Children with hearing loss in particular have shown deficits in consonant production, prosodic control, vowel duration, and mean length of utterance. This study examines the expressive language of preschool children with hearing loss using estimates of syllable production from 366 daylong audio recordings totaling over 4348 h of audio processed with unsupervised automatic speech processing techniques. We found no main effect of sex, but typically-developing children were more voluble on average. Unexpectedly, an interaction effect suggests that typically developing boys may be driving the observed differences. This work adds to the evidence of social and biological variability in the speech production of children, and is further proof-of-concept of developmental speech production work using massive data sets and automatic analysis methods.
Contextual influences on infants' attention to child-directed speech
Authors: Panneton Robin , McFayden Tyler , Bruce Madeleine , Taylor Caroline
Published: April 2019

Initial publications of infants' preference for infant (child)-directed speech (CDS) over adult-directed speech (ADS) produced a swift generalization to all early development. In fact, a recent meta-analysis found that the CDS preference to be robust (Dunst et al., 2012) and the ManyBabies I replication effort extends this view across labs, methods, and samples (Frank et al., 2018). Nonetheless, there are important demonstrations of how this preference gets attenuated and augmented by various factors. For example, Cooper et al. (1997) found that 1-mo-olds did not prefer CDS over ADS when both recordings were of the infants' own mothers, but did prefer CDS when the speakers were unfamiliar women. Other studies on CDS perception find influences of the language being spoken, the modality of presentation, the age of the infant, the clinical status of the mother and/or of the infant. The influence of context on infants' attention to speech is an underappreciated and understudied aspect of early language learning. This presentation will summarize contextual moderators of the CDS preference that emanate from the infant and from the infant's developmental milieu, and offer suggestions for other contexts that most likely impact infants' attention to CDS but have yet to be investigated (e.g., poverty).
Numerical investigation of the two-scale model for rough surface scattering
Authors: Olson Derek R.
Published: April 2019

The two-scale approximation for rough surface scattering assumes that a rough surface can be divided into two components: a large-scale and small-scale component, using a cutoff wavenumber to partition the wavenumber domain. This approach is attractive for multi-scale roughness such as the air-ocean and ocean-seafloor interfaces. Traditionally, the small roughness perturbation approximation is used for the small-scale component, and the Kirchhoff, or tangent-plane approximation is used for the large-scale component. Typically, the high-frequency approximation is used when propagating the surface fields to the far field, resulting in the physical interpretation of the large-scale surface modulating the local grazing angle of the small-scale surface. Using these approximations, the incoherent scattered power exhibits a dependence on the cutoff frequency, which is undesirable from a theoretical point of view. In this work, the validity of the approximations used on the small-scale surface, and large scale surface is examined through the use of numerical solution of the governing integral equations. This investigation is performed with the goal of testing the hypothesis that if each approximation on the component surfaces is demonstrated to be accurate, then the two-scale model should be independent of the cutoff frequency.
Application of Elastodynamic Finite Integration Technique (EFIT) to three-dimensional wave propagation and scattering in arbitrary geometries
Authors: Raley Sean , Dieckman Eric A.
Published: April 2019

Over several decades, railroad ultrasonic examination (UE) industry techniques have primarily been developed through simple analytical modeling and experimental approaches. However, with present-day computational capabilities, we can use numerical techniques such as the Elastodynamic Finite Integration Technique (EFIT) to fine-tune systems for complex applications before the fabrication process begins. EFIT is well-established as a useful method in numerical analysis of ultrasonic wave propagation with distinct advantages over the Finite Difference Time Domain method. Several software packages exist that use EFIT as the primary method for simulating the behavior of ultrasonic waves over time in two or three dimensions, but none of them are well-suited for railroad UE R&D. This paper explores the development of a tool developed for this purpose which was designed to: (1) allow for the input of various profile geometries, boundary conditions, and material inclusion geometries (such as a bolt hole in a railroad track); (2) allow for the input of specific ultrasonic impulses from varying emitter designs; and (3) produce verifiable results, as confirmed by experimental measurements.
Bayesian inference for water column and sediment inversion in ocean acoustics
Authors: Michalopoulou Zoi-Heleni
Published: April 2019

Bayesian methods provide inference on unknown parameters given prior beliefs and a statistical model for the observations in a noisy environment. It was shown in “Sequential filtering and linearization for inversion in the Seabed Characterization Experiment,” J. Acoust. Soc. Am. 144, 1913 (2018) how geometry and sediment parameter estimation in an oceanic experiment can be achieved with a two-stage Bayesian approach. Here, we demonstrate the potential of the method for inversion with a different data set presenting challenges in identifying features of the acoustic field necessary for the second stage of the estimation process. The water column sound speed is complex in this experiment, necessitating a complex inverse model. The transmitted signals are lfm pulses and probability densities of multipath arrival times are calculated at the receivers. For the forward and inverse calculations, we compute the Jacobian matrix for sound speed estimation using EOF coefficients. The inversion, employing the direct and surface and bottom paths, leads to inference on the geometry and the water column sound speed profile. Using the computed probability densities and introducing one more arrival, sediment property densities are calculated. Results are in excellent agreement with expected values for the site. [Work supported by ONR.]
Detection and imaging of prostate cancer using acoustic radiation force impulse imaging and quantitative ultrasound
Authors: Chen Hong , Morris D. Cody , Polascik Thomas , Foo Wen-Chi , Rohrbach Daniel , Palmeri Mark L. , Nightingale Kathryn , Mamou Jonathan
Published: April 2019

Transrectal ultrasound (TRUS) imaging is routinely performed to guide core-needle biopsies for the definitive diagnosis of prostate cancer (PCa). Needles are rigidly attached to the transducer and randomly sample the prostate yielding a high rate of false negative determinations. This study investigated the combined use of acoustic radiation force impulse imaging (ARFI) and quantitative ultrasound (QUS) to detect cancerous lesions in the prostate during TRUS imaging. Three-dimensional (3D) RF data from 12 PCA patients scheduled for radical prostatectomy were acquired over the full gland volume during ARFI data acquisition and used to obtain effective scatterer size (ESS), effective acoustic concentration (ESC), nakagami shape (µ), and nakagami scale (Ω) parameters. In each three-dimensional dataset, healthy and cancerous regions were obtained by manual segmentation using whole-mount histology slides. Linear discriminant and ROC methods were used to quantify the performance of ARFI displacements and QUS estimates at detecting PCa. Results for ARFI displacement and µ alone yielded an area under the ROC (AUC) curve of 0.84 and 0.69, respectively. The AUC value increased to 0.86 when µ and ARFI displacement were linearly combined. These results suggest that QUS and ARFI methods are sensitive to tissue properties affected by PCA. The proposed methods pave the way for novel real-time imaging of PCA during TRUS imaging. [Work supported in part by NIH Grants EB026233 and CA142824 and DOD PRCP Grant W81XWH-16-1-0653.]
The effect of musical training on ecological cocktail party listening
Authors: Schulz Anneliese K. , Hoffman Elissa , Monson Brian B.
Published: April 2019

A multitude of studies have investigated the phenomenon that experience, such as musical training, has an impact on listener performance in challenging auditory environments. Many studies examining speech-in-speech listening (i.e., the cocktail party problem) simulate an unnatural scenario where the target talker and maskers are all facing the listener. We analyzed participants’ performance in a more realistic situation with a target talker facing the listener and co-located maskers with head orientations facing away from the listener (45 or 60 deg relative to the listener). We aimed to determine if musical training provided an advantage to our participants under these ecological conditions. Stimuli were presented over a loudspeaker to listeners in a sound treated booth. Preliminary data indicate that highly trained musicians (N = 6) perform better than nonmusicians (N = 25) in our task. Musical training may improve auditory functioning in challenging ecological listening situations. Data collection for listeners with extensive musical training is ongoing.
Effects of self-reported hearing difficulty on intensity discrimination judgments
Authors: Saccocia Gwen O. , Toscano Joseph C.
Published: April 2019

Listeners may report difficulty understanding speech, particularly in background noise, despite having normal audiograms that do not suggest a sensorineural hearing loss. One potential cause of this hearing difficulty is auditory neuropathy (AN), a disruption in the function of the auditory nerve. AN may specifically affect auditory nerve fibers that code intensity differences at higher sound levels, resulting in particular difficulty with speech recognition but preserved audiometric thresholds. This study aims to detect AN by measuring intensity discrimination thresholds at different frequencies and sound levels, comparing performance to self-reported measures of hearing difficulty. Listeners performed an intensity discrimination task where they heard pairs of tones and judged whether the first or second tone was louder. Psychophysical functions were computed to measure listeners' discrimination thresholds and point of subjective equality (PSE, i.e., point at which the two tones are judged to have equal intensity). Results showed that listeners who report greater speech-in-noise difficulty had shifted PSEs specifically at higher sound levels (60–70 dB SPL, the range used in conversational speech), such that they were more likely to perceive the second tone as louder than it was. The results suggest that an intensity discrimination task may be a useful test for AN.
Factors influencing auditory localization with deep insertion hearing aids or earplugs
Authors: Brungart Douglas , Spencer Nathaniel , Pryor Nina , Thompson Eric R. , Iyer Nandini , Romigh Griffin D. , Simpson Brian
Published: April 2019

Virtual localization experiments have demonstrated that Head Related Transfer Functions measured a few millimeters inside a blocked ear canal can produce localization performance approaching what is measured in the free field. This suggests that an earplug inserted entirely inside the ear canal should be able to preserve normal localization performance so long as the stimulus is loud enough to overcome any insertion loss in the device at all frequencies. In this study, localization performance of normal-hearing listeners was measured with the Lyric extended wear hearing aid, both in active mode (where it acted like an electronic pass-through earplug) and in passive mode (where it acted like a passive hearing protector). In an active mode, localization accuracy approached the open-ear condition. However, under the passive condition, localization was much worse than with the open ear even at high stimulus levels where the full spectrum should have been audible. This result suggests there may be fundamental limitations on localization accuracy with passive hearing protection that are unrelated to the directionality of the HRTF. [The views expressed in this abstract are those of the authors and do not reflect the official policy of the Department of the Army/Air Force, Department of Defense, or U.S. Government.]
Executive functions predict improvements in pure-tone thresholds for children with normal hearing and children with hearing loss
Authors: McCreery Ryan W. , Leibold Lori , Buss Emily , Walker Elizabeth
Published: April 2019

Detection of pure tones is known to improve in early childhood. The ability to suppress self-generated noise during detection tasks has been identified as a contributing factor to higher audiometric thresholds in children. Data from children with hearing loss indicate that children with thresholds that are above the level of self-generated noise do not show the same improvements across age as peers who can hear their self-generated noise. In an effort to examine the specific cognitive mechanisms that affect this process, audiometric thresholds and executive functions skills were measured in a group of 213 1st and 3rd grade children (84 children with normal hearing, 129 children with hearing loss). The relationship between selective attention and vigilance and thresholds were assessed for both groups. Children with stronger selective attention and vigilance skills had lower pure-tone thresholds than peers with poorer skills in these domains. The previous finding that children only showed an improvement in thresholds when they could hear their self-generated noise was also replicated. Audiometric test equipment that can monitor the sound level in the ear canal may help to increase the accuracy of clinical pure-tone detection tasks in children.
Power transmission metrics and applications in the design of quiet structures
Authors: Young Jonathan D. , Myers Kyle R.
Published: April 2019

Connected structures subject to applied dynamic loads transfer vibrational energy through their connecting junctions. Identifying the dominant paths of transmission and characterizing the power flow through those paths is important for designing a quiet structure. When the connection type is known, one way of characterizing the transmitted power flow is to identify which degrees of freedom (i.e., translational and rotational) is most responsible for transmission through the junction. Another way could identify vibrational modes that dominate the transmission. This research presents several examples that characterize power flow between structures in physical and modal space. The structures examined here may be connected through springs, point impedances, or a generalized impedance matrix. Key questions considered are how changes to the system affect transmitted power, and how the results can be used to design quieter structures.
Statistics of acoustic waves propagating through turbulent media
Authors: Blanc-Benon Philippe
Published: April 2019

Propagation of acoustic waves through atmospheric turbulence is relevant to different problems : outdoor sound propagation, blast waves generated from explosions or gunshots, propagation of sonic booms. While propagating in turbulent air, acoustic waves are distorted by the combined effects of diffraction and scattering induced by atmospheric inhomogeneities. Accurately controlled experiments are needed to validate theoretical models for sound propagation in inhomogeneous media. In this paper, probability distribution functions will be presented for linear and nonlinear acoustic wave propagation through thermal or kinematic turbulence. Experimental data will be compared with numerical simulation using parabolic approaches. [Work supported by the Labex CeLyA of Université de Lyon, operated by the French National Research Agency (ANR-10-LABX-0060/ ANR-11- IDEX-0007).]
Machine learning methods for estimating probability density functions of transmission loss: Robustness to source frequency and depth
Authors: Lee Brandon M. , Dowling David R.
Published: April 2019

Predicted values of transmission loss (TL) in ocean environments are sensitive to environmental uncertainties. The resulting predicted-TL uncertainty can be quantified via the probability density function (PDF) of TL. Monte Carlo methods can determine the PDF of TL but typically require thousands of field calculations, making them inappropriate for real-time applications. Thus, a variety of alternative techniques based on polynomial chaos, field shifting, modal propagation in ocean waveguides, and spatial variations of TL near the point(s) of interest have been proposed. Recently, an approach to estimating the PDF of TL based on nominal TL, ocean environmental parameters, and machine learning was found to have a success rate of 95% with constant source depth (91 m) and frequency (100 Hz) when tested on 657,775 receiver locations within 100 randomly selected ocean environments. This presentation describes an extension of this approach and its success predicting the PDF of TL for different source depths and frequencies for ranges up to 100 km. This increase in the size of the parameter space furthers the need for a sophisticated method of choosing training examples. Such a method is proposed, and its performance is compared to that of prior techniques. [Work supported by ONR.]
Real-time auralization of a talker’s own voice in virtual rooms
Authors: Whiting Jennifer , Leishman Timothy W. , Neilsen Traci
Published: April 2019

While much has been done in the field of sound auralization in virtual rooms, the problem of hearing one’s own voice in these environments has received less attention. A robust and feasible system for real-time auralization of talkers who are also listeners is needed. To address this requirement, a real-time convolution system (RTCS) was designed with the specific goal of “placing” a talker/listener in virtual acoustic environments. This system necessitated the development of several tools and methods. Oral-binaural room impulse responses were measured and characterized for a variety of room. The RTCS improved on past systems, in part through the derivation and inclusion of compensation filters, which corrected the linear auditory distortions of the RTCS components. Objective measures in the time- and frequency-domains were developed to assess the validity of the system. A jury-based listening study also indicated that RTCS users could speak and listen to their own voices in the virtual acoustic environments in a natural manner.
Empirical evaluation of in-field, binaural record and playback reproduction
Authors: Neale William , Terpstra Toby
Published: April 2019

This research evaluates a methodology for calibrating in field, sounds for playback in a separate, interior environment. The ability to record sounds in the field and playback them accurately in a different environment is useful when the end user, or listener cannot be present at the location where the sound is being produced live. In forensics, for example, an expert or juror may need to evaluate an acoustic or auditory issue but not have access to the site where the sound is produced. The methodology presented here utilizes a binaural microphone where participants in the field, listen to a physical sound, and calibrate the binaural microphone by adjusting recording levels until the sound heard in their headphones matches the sound being produced live in the field. A second group of participants are presented with the same live physical sound but in an interior environment. Using the same setup, these participants compare the live sound with the recorded and reproduced sound calibrated by the in-field participants. Participants in this second group empirically evaluate the similarity of the reproduced sound to the live physical sound in the interior environment.
Comparisons of inverse and forward problem approaches to elastography
Authors: Ghavami Siavash , Adabi Saba , Babaniyi Olalekan , Alizad Azra , Aquino Wilkins , Fatemi Mostafa
Published: April 2019

We present a full-wave inversion approach with total variation regularization for elastography. The proposed method is based on the minimization of an error in constitutive equations functional augmented with a least squares data misfit term referred to as MECE for “modified error in constitutive equations.” The main theme of this paper is to demonstrate several key strengths of the proposed method on experimental data. In addition, some illustrative examples are provided where the proposed method is compared with a common shear wave elastography (SWE) approach. To this end, ultrasonically tracked displacement data from an acoustic radiation force (ARF) pulse are used in different phantoms including phantom with layered inclusion and triangle inclusion. The results indicate that the MECE approach can produce accurate shear modulus reconstructions in comparison with SWE, especially around the sharp edges in the layered and triangle inclusions. We compare shear modulus reconstruction using MECE and SWE with original inclusion shapes using two-dimensional normalized zero mean cross correlation, edge preservation index and dice coefficient similarity index. [Work supported by NIH Grant R01 CA174723.]
Optimization of molecular delivery to red blood cells using an ultrasound-integrated microfluidic system
Authors: Murphy Emily M. , Priddy Mariah C. , Janis Brett R. , Menze Michael A. , Kopechek Jonathan A.
Published: April 2019

The shelf-life of donated red blood cells (RBCs) for transfusions is currently limited to six weeks when stored under refrigeration. This causes supply shortages worldwide and prevents transfusions in locations that lack access to cold-chain storage. Recently, a new approach to store RBCs as a dried powder at ambient temperature was developed. This method utilizes an ultrasound-integrated microfluidic platform to induce intracellular delivery of compounds that protect cells during desiccation and rehydration. The objective of this study was to detect cavitation emissions in order to optimize parameters for molecular delivery to RBCs in this system. Ultrasound was continuously generated in the microfluidic channels using an 8-MHz PZT plate and acoustic emissions were passively detected with an identical PZT plate aligned coaxially. Fluorescein and lipid-coated microbubbles were added to RBC solutions in order to nucleate cavitation and enhance intracellular molecular uptake as measured by flow cytometry. Increased levels of broadband emissions were detected at microfluidic flow rates associated with higher fluorescein delivery to RBCs. These results suggest that inertial cavitation plays an important role in enhancing molecular delivery to RBCs in the microfluidic channels. Optimization of this system may enhance delivery of protective compounds for long-term preservation of blood.
Modeling the vibration of a thin bar using SimScape
Authors: Childs Carter J. , Thompson Stephen C.
Published: April 2019

The standard treatment of longitudinal and flexural vibrations of thin bars follow the methods described by Raleigh. The solution for longitudinal vibrations is completely analogous to electrical signals in electrical transmission lines. Thus, longitudinal mechanical vibrations can be modeled using lumped or distributed parameter analog circuits. The same is true of transverse vibrations of perfectly flexible strings. However, when bending stiffness is included for transverse vibrations, the simplicity of the transmission line analogies is not present. The authors are not aware of a lumped parameter model of the flexural vibration of a thin bar that includes the effects of bending stiffness. This paper presents a lumped parameter model for a thin bar that provides accuracy similar to that of a lumped parameter model of a flexible string. The differential length element of the bar is modeled in the same way as the differential element in the standard treatment of bra vibrations. The model will be demonstrated in the SimScape modeling software, though it can also be implemented in Modelica and possibly in some versions of SPICE.
Impedance measurements of acoustically nonlinear engine components
Authors: Van horn Eric , Humphreys Luke , Scarborough David E.
Published: April 2019

Currently, the acoustic analysis of combustion systems generally consists of simplified impedance networks. For effective simulation, the impedance of these components must be known, for which there is a large gap in the current knowledge. This study examines the acoustic impedance for various different types of gas-turbine engine components, including acoustically nonlinear components such as swirlers and orifice plates. Experimental results are obtained using a specially designed impedance tube. Acoustic pressure and velocity measurements are made using a multiple microphone method. The impedance is then calculated using the reflection coefficient, and impedance subtraction used to isolate the test article. This method obtains accurate results within a relatively wide range of frequency values, 100–1500 Hz for this study. Amplitude sweeps conducted for each test article demonstrate the nonlinear aspects, if any, for each test article. These results are then compared to acoustic simulations conducted in COMSOL to assess the capabilities and shortcoming of COMSOL’s linear acoustic package to provide predictions of the acoustic impedance of these components. The results for this are intended to provide valuable data for modeling the acoustics of combustion systems, as well as demonstrate an effective method for obtaining impedance data for various acoustic components.
Absorption measurement of acoustic materials using a spherical microphone array
Authors: Dupont Samuel , Melon Manuel , Berry Alain
Published: April 2019

Standardized methods for the sound absorption measurement are restricted to normal or diffuse incidence. The capture of the sound field over a plane material sample using a spherical microphone array has already been proposed as a solution to measure surface impedance or sound absorption. However, the proposed solutions use either modal beamforming or a direct computation of the pressure on the sphere. In this presentation, a method which uses the spherical harmonics expansion to calculate the absorption using the spherical holography principle is proposed. It allows to measure the characteristics of the material without relying on an accurate definition of the sound scene such as the exact position of the source but only on the distance of the spherical microphone to the material. Simulation and experimental result of surface impedance and sound absorption will be presented as well as comparisons with another approach from the literature based on sparse array processing of spherical antenna.
The description of fan noise by indexes based on the specific loudness
Authors: Töpken Stephan , van de Par Steven
Published: April 2019

In a previous study of the authors, a broad variety of fan sounds that were equalized in overall A-weighted level was rated in listening experiments with a semantic differential. The factor analyses of the ratings indicated six perceptual dimensions and five groups of sounds, which shows the rich variety of sound characteristics covered by the tested fan sounds. The results showed that the groups of pleasant and unpleasant sounds differed mainly with respect to the first three perceptual dimensions, “pleasant,” “humming/bass,” and “shrill.” An analysis of the specific loudness according to the DIN 45631 standard revealed systematic differences in the specific loudness patterns for the different groups of fan sounds. It was possible to define two psychoacoustic indexes that correlate highly with the factor values of the three most important perceptual dimensions of fan noise. The most important index, Nratio, relates the amount of loudness resulting from low mid-frequency content between 2 Bark and 5 Bark to the loudness from high frequency content above 10 Bark. The identified boundaries of the frequency ranges employed in the indexes are in good agreement with those found for air conditioning noise, air cleaners and in the context of sound masking in offices.
Developing a tone standard for air-conditioning and refrigeration equipment
Authors: Knight Derrick P.
Published: April 2019

AHRI Technical Committee on Sound is continuing the redevelopment of standard AHRI 1140—Sound Quality Evaluation Procedures for Air-Conditioning and Refrigeration Equipment. We are currently evaluating the feasibility of harmonizing this standard with a current ASHRAE funded study whose goal is to determine the threshold of annoyance due to tones in HVAC equipment. However, from a manufacturer’s perspective, it is very difficult to accommodate a metric measured in the listener’s space. Additionally, sound power test methods for HVAC equipment allow testing in a reverberant field, which poses significant challenges to measuring tones. This presentation will provide an update in regards to the development for standard AHRI 1140 and will seek feedback from consultants and academics.