bluuebunny/crossref_metadata_2025 huggingface dataset:
Linear and nonlinear Bayesian localization in ocean acoustics
Authors: Dosso Stan
Published: December 2020

Ocean-acoustic localization can be considered an inverse problem that involves estimating model parameters that specify the location of one or more acoustic sources and/or receivers based on fitting measured acoustic data, which can include observable quantities such as travel times, travel-time differences, modal dispersion, or acoustic-field structure. In a Bayesian inversion approach, data and prior information are used to compute the posterior probability density (PPD) of the model parameters, providing uncertainty analysis that quantifies the information content of the problem. The Bayesian formulation provides the generality to treat all uncertain parameters (e.g., both source and receiver locations, environmental properties, clock drifts) as unknowns subject to appropriate levels of prior information. Marginalizing over nuisance parameters can improve localization accuracy or at least account for parameter uncertainties in the localization uncertainty. Some Bayesian localization problems can be solved efficiently using linearization and iteration, with closed-form approximations for the PPD. In other cases, nonlinear (numerical) methods such as Markov-chain Monte Carlo sampling or trans-dimensional inversion are required. This talk will illustrate these concepts with a series of examples including array-element localization for moored and towed arrays, tracking autonomous underwater vehicles at a test range, marine-mammal localization, and multi-source matched-field localization
Determination of sperm whale orientation with respect to a single hydrophone
Authors: Drouant George , Ioup Juliette W.
Published: December 2020

Sperm Whales (Physter macrocephalus) produce echolocation clicks composed of several pulses while searching for food when diving. An estimate of a whale's length can be calculated by determining the time interval between consecutive pulses in the echolocation click. That interval is the interpulse interval or IPI. We have developed methods to estimate the IPI of whales and thereby determine their lengths. The structure of a click from a sperm whale approaching a hydrophone is different from that of a whale moving away from a hydrophone (Zimmer, 2005). The methods we use to determine IPIs differ depending upon whether the clicks analyzed are from an approaching or leaving whale. Continuous Wavelet Transforms are used to determine if the clicks to be analyzed were produced by an approaching or leaving whale. The IPIs of data files from a mixture of approaching and leaving whales were analyzed by our method with good agreement with manual determinations of the IPIs.
An overview of new testing results on common wood joist and truss assemblies
Authors: Raley Michael
Published: December 2020

This presentation is an overview of new testing results for common 18 in. open-web truss, TJI, and 2 × 10 joist assemblies with gypsum concrete poured directly to the plywood subfloor. The presentation will discuss the effect of underlayment thickness, underlayment attachment (glued versus loose), and floor finish. It will also cover the difference in IIC and HIIC ratings for all tested iterations of the assembly, showing how the HIIC rating gives greater differentiation between flooring and underlayment combinations.
An architectural investigation of mitigating noise to improve speech intelligibility in an open studio environment
Authors: Kania Christopher W. , Azad Hassan , Gold Martin
Published: December 2020

This research project proposes a series of solutions to mitigate noise and improve speech intelligibility within an open architectural studio environment. Open studio environments pose a unique challenge compared to conventional open office environments. In addition to typical sources of noise found in open offices, such as conversation between co-workers, open studios contain noise generating equipment, such as plotters, 3-D printers and laser cutters. There is substantial research and evidence from the Finnish Institute of Occupational Health and AINS Group which conclude that different sources of noise in an open office environment hinder employee productivity. However, there is limited research that focuses on open architectural studio environments. Existing research regarding productivity, as it relates to acceptable noise level, will serve as a basis for application of Digitally Enhanced Sonic Enclosures (DESE) to mitigate noise within the open studio. Revit 2020, Rhinoceros 6 and Ease 4.4 will be utilized to analyze thesonic environment as it relates to noise and speech intelligibility in the CityLab Orlando design studio. Ultimately, this research offers an effective series of solutions, which can serve as architectural design guides to noise-related challenges in open studio environments.
Visualization of the bullfrog middle ear
Authors: Ketten Darlene , Simmons Andrea M.
Published: December 2020

The structure and function of the anuran middle ear has been explored both physiologically and structurally. It is similar to that of some other vertebrates (birds and reptiles) in that it has a two-ossicle system consisting of an extracolumella and a columella. However, there are notable species and gender variations. Peter Narins has made significant contributions to our understanding of this unusual middle ear. One example is that the middle ear of terrestrial frogs has a cartilaginous operculum adjacent to the columellar footplate. Following on Peter's work, to better understand the middle ear in situ, we obtained Micro CT and Ultra High Resolution Helical (UHR CT) scans of the middle ear in intact heads of the bullfrog (Rana catesbeiana) on a Zeiss Xradia 520 Versa and a Siemens Volume Zoom at 10–100 μm isotropic voxel resolutions. Image analyses showed the core of the columella in this species is not a simple column but a twisted shaft. Further, the extracolumella is not constructed of dense cartilage but rather is a complex with exceptional soft, semi-cartilaginous tissues. Implications of these findings for middle ear function will be discussed.
Good vibrations: The ground-shaking career of Peter Narins
Authors: Christensen-Dalsgaard Jakob
Published: December 2020

Vibration signals are detected and used for communication by many different animals, and anurans—frogs and toads—are among the most sensitive. In this talk, I will review the current status of knowledge of anuran vibration sensitivity, largely based on the research by Peter Narins and collaborators. Although mechanical stimuli potentially can excite a variety of receptors, the most sensitive vibration receivers are found in the inner ear of anurans, specifically in the otolith organ sacculus and in the low-frequency hearing organ, the amphibian papilla, responding to whole-body vibrations at frequencies from 10 to 200 Hz. Substrate vibrations, in nature mostly generated as Rayleigh waves in the soil, are transmitted through the body to the inner ear, and the thresholds of the receptors to substrate acceleration are as low as 0.001 cm/s2 in some species. This sensitivity is employed for various purposes by the anurans. A general use probably is warning against approaching predators, and some species have been reported to use vibrational communication. However, very few species of anurans have been studied extensively, and it is likely that vibrational communication is much more common, especially at close ranges, where vibration signals provide a relatively private information channel.
Modeling of 3-D elastic waves in nonlinear elastic solids using the iterative nonlinear contrast source method
Authors: Selvam Sundaraelangovan , Volker Arno , van Neer Paul L. , de Jong Nico , Verweij Martin D.
Published: December 2020

In nondestructive testing, the generation of higher harmonics and the mixing of elastic waves are used to measure the nonlinearity parameters, which in turn are closely related to the microscopic state of the material. A 3-D numerical tool that can simulate large scale, four-dimensional, nonlinear elastic wavefields would be very useful for the reliable interpretation of experimental results. Here, a method is presented that can efficiently compute the nonlinear displacement fields in a homogeneous, isotropic elastic medium, taking into account its third-order elastic constants (A, B, C). The method is based on the Neumann iterative solution of an integral equation involving a Green's function of the linear `background' medium, and a contrast source representing the nonlinearity of the medium. The integral equation is solved iteratively, and the computations are based on Fast Fourier Transforms using a sampling rate close to the Nyquist limit, i.e., two grid points of the shortest wavelength. The displacement fields are evaluated using the scalar and vector potential functions representing the compressional and shear displacements. In this presentation, the suitability of the INCS method for modeling the harmonics of 3-D nonlinear elastic waves and its validation by comparison with an analytical benchmark solution, will be presented.
Quantitative assessment of human cervix with correlation length ratio during pregnancy: An in vivo longitudinal study
Authors: Kari Mohammadreza , Carlson Lindsey C. , Feltovich Helen , Hall Timothy J.
Published: December 2020

We recently introduced a novel parameter called the correlation length ratio (CLR), a ratio of lateral to axial correlation lengths for backscattered echo signals, to detect the presence of elongated structures in soft tissues. Here, we look at variation of CLR and presence of elongated structures in human cervix during pregnancy using a longitudinal data from a group of women with normal pregnancy. Thirty women, ages ranging from 19 to 37years, were scanned with ultrasound at five time points beginning at their normal first-trimester screening (8 –13 weeks) through term pregnancy (nominally 40 week). We computed correlation lengths, and CLR. To account for the system point spread function, an empirical cumulative distribution function of the CLR was obtained from a reference phantom. A one-sided threshold of 95% of the CDF was then computed. The difference between CLR in the sample and the threshold was computed and its variation with increasing gestational age was obtained. CLR estimation demonstrated a gradient along the length of the cervix. This longitudinal study also demonstrated an increase of about 0.5% (per week) in lateral correlation length and 0.8% increase in CLR with increasing gestational age, while axial correlation length was almost constant.
Analysis of three-dimensional echo decorrelation and integrated backscatter imaging during ex vivo radiofrequency ablation
Authors: Ghahramani Z. Elmira , Grimm Peter D. , Dayavansha E. G. Sunethra , Eary Kathryn , Swearengen Michael , Mast T. Douglas
Published: December 2020

Radiofrequency ablation experiments were performed in ex vivo bovine liver (N = 14) using a clinical ablation system (RITA 1500X generator and StarBurst probe, Angiodynamics). Three-dimensional (3-D) ultrasound images were acquired as complex beamformed echo volumes from a Siemens Acuson SC2000 scanner with a 4Z1c matrix array. Echo decorrelation images, depicting echo changes between sequential volumes (interframe time 18 ms), and integrated backscatter (IBS) images, depicting local changes in echogenicity relative to baseline, were computed in 3-D at 11 s intervals throughout each treatment. To assess potential for real-time prediction of tissue ablation, cumulative 3-D echo decorrelation and integrated backscatter images were compared to reconstructed ablation zones, segmented from optically scanned tissue sections. Both echo decorrelation and IBS provided good prediction of local ablation using receiver operator characteristic (ROC) curve analysis (area under curve 0.91 for echo decorrelation normalized to global echo energy; >0.85 for all parameters), with accuracy depending weakly on correlation window size. While ablation regions were predicted fairly well (Dice coefficients >0.6), ablation zone volume was not consistently predicted by thresholded parameter maps. Both echo decorrelation and IBS showed weak but statistically significant correlation with simultaneous, co-located tissue temperatures measured by four thermocouples on the RF probe.
Construction of axisymmetric equivalent sources to facilitate the simulation of nonlinear acoustic fields in therapeutic ultrasound
Authors: Kreider Wayne , Rosnitskiy Pavel B. , Yuldashev Petr V. , Sapozhnikov Oleg A. , Khokhlova Tatiana D. , Peek Alex T. , Khokhlova Vera
Published: December 2020

The development of new clinical applications of therapeutic ultrasound has been accompanied by efforts to standardize simulation methods for predicting nonlinear ultrasound fields. Although software tools for simulating nonlinear ultrasound propagation are increasingly available, computational burdens remain high, especially for fields characterized by strong focusing and significant harmonic content. Because nonlinear effects in such fields accumulate primarily over a short axial distance within the focal lobe, the nonlinear field can be approximated by considering an equivalent source with a similarly shaped focal lobe in the linearly focused beam. If an axisymmetric equivalent source can be identified, even strongly nonlinear fields can be accurately simulated with minimal computational burden using the Khokhlov-Zabolotskaya- Kuznetsov model. This approach has been implemented and validated in water for several real sources using only a simple set of linear field measurements to characterize the focal lobe of each source. To demonstrate the breadth of utility of this approach, holograms of non-axisymmetric fields distorted by phantoms were also used to define equivalent sources and estimate in situ nonlinear fields. Fast holography measurements combined with equivalent-source simulations can efficiently characterize the impact of different phantom geometries on nonlinear fields. [Work supported by NIH R01EB025187 and R01EB007643, and RSF 19-12-00148.]
Shock formation distance—A design parameter for high power acoustic energy transfer systems
Authors: Meesala Vamsi C. , Hajj Muhammad , Shahab Shima
Published: December 2020

An interesting consequence of the nonlinear propagation of a finite-amplitude acoustic wave is the formation of a discontinuity in the pressure or also known as shock formation. It is associated with the dissipation of energy that is proportional to the cube of jump in the discontinuity. Such a loss in energy is detrimental for acoustic energy transfer applications as it will compromise the energy transfer efficiency. As such, the knowledge of the shock formation distance (SFD) is essential for designing efficient high-power energy transfer systems. We present an analytical frequency domain approach capable of predicting the SFD in the acoustic pressure distribution generated by a baffled disk with a general transverse deformation in a weakly viscous fluid medium. The nonlinear wave propagation is modeled using the Westervelt equation and the approach is based on solving it using the method of renormalization. The approach can be implemented either analytically or numerically to predict the SFD much faster than the time-domain simulations. The numerical implementation also allows the flexibility of using this approach for any source configuration. [This work was supported by NSF Grant No. ECCS-1711139, which is gratefully acknowledged.]
Ultrasonic measurements of the femoral neck in human volunteers using the backscatter amplitude decay constant
Authors: Delahunt Sarah I. , Downey Kiera L. , Georgiou Loukas A. , Gray Aubrey J. , Thomas Doni M. , Pirro Gia , Newman Will R. , Main Evan N. , Moore Joshua T. , Hoffmeister Brent K.
Published: December 2020

Osteoporosis is a degenerative bone disease that affects millions of people worldwide. The goal of this study was to test a new ultrasonic technique developed for clinical bone assessment called the backscatter amplitude decay constant (BADC). Ultrasonic backscatter measurements were performed on 97 volunteers at the left and right femoral necks using an ultrasonic imaging system (Terason T3000) equipped with a 3.5 MHz convex array transducer. The backscatter signals were analyzed to determine the backscatter amplitude decay constant (BADC), a parameter that measures the exponential decay in the amplitude of the backscatter signal. For comparison, additional ultrasonic measurements were performed at the left and right heels using an ultrasonometer (GE Achilles EXPII) to measure the stiffness index of the calcaneus. BADC demonstrated weak but statistically significant correlations with stiffness index (R < 0.25, p < 0.05). With further refinement of the measurement technique, BADC may be a useful parameter for ultrasonic bone assessment.
Converting performance spaces into lecture halls
Authors: Beaudoin Erin , Hoffman Kurt R.
Published: December 2020

Identifying classroom spaces able to accommodate students consistent with social distancing guidelines is a major logistical concern for Academic institutions attempting to have in-person instruction during the pandemic. The solution to this problem is to adapt larger campus spaces such as gymnasiums, public spaces, or performance venues, for classroom usage. This work focuses on measuring important acoustical parameters in these planned lecture spaces such as reverberation time (T20), speech clarity (C50), background noise decibel level, and sound pressure level differences in a grid pattern in the room. We studied existing classrooms as well as the target spaces for comparison and to optimize the parameter values for the new lecture spaces. Acoustic measurements were taken and analyzed using a sine sweep method with a calibrated microphone. The T20 of the rooms were calculated using a Sabine model to compare with the measured values and to guide plans for reducing T20 to transform the spaces to host lectures and discussion. Because the gymnasiums will also revert to the normal function, the proposed solutions must be temporary and easily added or removed.
Acoustic metasurfaces as sound diffusers and diffsorbers
Authors: Kang Janghoon , Parker Samuel D. , Skeens Joe , Treweek Benjamin C. , Walsh Timothy , Haberman Michael R.
Published: December 2020

Acoustic metasurfaces (AMS) may offer additional design space for the creation of sound diffusers and diffsorbers. We present the design and experimental characterization of an AMS created to diffuse sound fields using a treatment of uniform thickness. The AMS unit cell designs were chosen to minimize viscous losses while enabling control of reflected phase at each point of the AMS. The design geometry was then optimized with a parametric sweep of unit cell dimensions using finite element (FE) models where the target phase shifts are associated with a one- and two-dimensional quadratic residue diffuser (QRD). Samples were fabricated using additive manufacturing and impedance tube measurements were conducted to validate FE predictions. Modeled and measured reflection coefficients were shown to be in good agreement. The scattered field was then measured in an anechoic chamber using the logarithmic frequency modulated chirp excitation and the deconvolution methods to provide narrowband and broadband estimates of sound diffusion performance. Overall performance is presented for narrow-band and broadband considerations. The AMS response is compared and contrasted with traditional QRD designs, highlighting differences in frequency- and angle-dependence as well as temporal diffusion and absorption. [S.N.L. is managed and operated by NTESS under DOE NNSA Contract No. DE-NA0003525.]
Internal gestural coordination for derived long nasals
Authors: Oh Miran , Byrd Dani
Published: December 2020

Nasal consonants have been studied mainly by investigating acoustic nasal energy or the oral gesture's constriction, while less attention has been paid to how velic and oral components in nasals temporally interrelate. Given that nasals essentially require specific timing between oral and velum gestures—that is, oral closure must occur when the velum is sufficiently low—it is important to understand the regularity of this coordination. By examining the relative timing of oral and velum gestures in nasals of Seoul Korean, this real-time MRI study aims to illuminate the gestural organization of various nasal structures. Target stimuli include onset nasals (/#n/), coda nasals (/n#t/ & /n#p/), and juncture geminate nasals (both concatenated /n#n/ and assimilated /t#n/). Findings show that concatenated and assimilated geminates crucially differ in their gestural coordination and their variability. Concatenated geminates and coda nasals show similar oral-velum timing relations, while some assimilated geminates show an onset-like coordination. Furthermore, while both geminates show more extended overlap between oral and velum gestures than onset nasals, assimilated geminates exhibit greater interspeaker variability. This suggests that the internal coordination for assimilated nasal geminates is less rigidly (or stably) organized, exhibiting characteristics of both singleton onset nasals and geminate nasals. [Work supported by NIH.]
Articulation of non-normative variants of L1 and L2 Spanish trill /r/
Authors: Kim Ji Young , Faytak Matthew , Repiso Puigdelliura Gemma , Mauffray Erin
Published: December 2020

This study examines within-speaker variability in L1 and L2 Spanish trill production. The Spanish trill is canonically produced with two or more brief contacts between the tongue tip and the alveolar ridge, Although multiple tongue-palate contacts is considered the norm, some non-normative variants across Spanish dialects involve fewer contacts with frication (e.g., tap followed by fricative; sibilant fricative). L2 phonology research shows that English speakers are known to associate frication with /r/ and produce frication for /r/ themselves. However, it is unclear whether these variants are articulated with similar tongue posture to those of native speakers or whether differences are due to aerodynamic factors. Synchronized ultrasound and acoustic recordings of trill production were made for three Spanish native speakers and four English L2 learners of Spanish. Trill realizations will be classified as normative trill, variants involving frication, or other from the acoustic signal. Comparison of tongue contours before, during, and after trill initiation will be carried out to examine the nature of the articulation of non-normative variants.
Lateral articulation of the Spanish trill /r/
Authors: Mauffray Erin , Faytak Matthew , Kim Ji Young , Repiso Puigdelliura Gemma
Published: December 2020

The Spanish trill /r/ represents a rich area for language acquisition research because of its particular articulatory requirements and its tendency toward variation. Lateral bracing has been documented during production of the canonical apical trill. Some articulatory studies suggest alternate lateral articulations of the Spanish trill, with lateral bracing on one side and vibration on the other, which are not distinguishable from central trills from the acoustic signal [Rivera-Campos and Boyce, “Describing alternative articulations of the Spanish trill /r/ by ultrasound technology,” JASA 133(5)]. With the aim of replicating these findings, the present study uses ultrasound imaging in midsagittal and coronal planes to characterize tongue position and movement during different phonetic variants of /r/ produced by seven speakers (four L2 Spanish learners and three native Spanish speakers). The study will shed light on the frequency of the central and lateral strategies in native Spanish speakers and L2 learners, whether the presence of frication or failure of trilling is connected to the lateral strategy, and will contribute to the general understanding of covert articulatory variants.
A large-scale comparison of the intelligibility of unit-selection and deep-neural-network parametric synthetic voices generated from dysarthric speech
Authors: Lilley Jason , Hyppa-Martin Jolene , Bunnell H. Timothy
Published: December 2020

We report on a large-scale intelligibility study of 773 listeners who transcribed semantically unpredictable stimuli generated from 4 synthetic voices: two synthetic voices, a unit-selection voice and one based on deep neural network (DNN) parametric synthesis, from the recordings of each of two dysarthric speakers. Intelligibity was calculated as the normalized phonemic edit distance (NPED) between perceived and actual transcriptions. The DNN-based voices (NPED 0.286) were significantly more intelligible (p < .001) than the unit-selection voices (NPED 0.316), although there was a significant interaction (p = .034) with the structure of the synthesized sentence. Counterintuitively, the voices generated from the more severely dysarthric speaker (NPED 0.272) were signficantly more intelligible (p < 0.001) than the other speaker's voices (NPED 0.329). Post-hoc analysis demonstrated that while the more dysarthric speaker's speech had poorer vocal quality, was measurably slower and more variable in duration, and had a smaller vowel space, this speaker also had significantly (p > .001) higher formant amplitudes, narrower bandwidths, and less frequency variance; she also had more careful articulation during recording. We conclude that individual differences (some within the speaker's control) can override gross measures of dysarthria in determining synthetic voice intelligibility.
Acoustic-phonetic analysis of speech following a lobectomy or esophagectomy
Authors: Khan Babar , Stokes Michael , Khan Sikandar , Seyffert Sarah
Published: December 2020

An observational study was conducted to monitor and detect the onset of altered level of consciousness and delirium in patients after a major non-cardiac thoracic surgery. Speech recordings from patients were recorded pre-operatively and once daily in the post-operative setting until hospital discharge. A vocabulary consisting of vowels in a coarticulatory neutral environment is used to identify differences in timing or typical articulatory movements that would be indicative of impairment due to delirium. More than one recording session across days is needed in order to compare the patients' speech to their own speech to identify patterns and changes for that talker. Programming has been developed that utilizes the Praat software package to take acoustic-phonetic measurements of pitch, formant frequencies, and amplitude every 6 ms. This processing has generated tens of thousands of rows of data across 1,166 h-vowel-d words reflecting typical patterns for each of the 16 subjects with more than one recording session. This unique dataset has led to insights that go beyond the original intent of identifying the potential onset of delirium including patterns of dyspnea resulting from the surgery. The initial findings from mining the extensive dataset will be presented.
Braid representation of the shallow water acoustic channel to interpret temporal evolution of multipath arrivals
Authors: McCarthy Ryan A. , Sen Gupta Ananya
Published: December 2020

We present a morphological representation of the underwater acoustic channel that employs geometric braids to gain real-time knowledge of the dominant multipath activity. The key idea is to incorporate braid manifolds in tandem with non-convex mixed norm optimization techniques to track the temporal evolution of multipath arrivals. Specifically, we focus on channel braids that manifest as rapidly fluctuating high-energy taps in the delay spread as well as the delay-Doppler scattering function. Multiple braids can also be topologically combined using braid operations to interpret oceanic phenomena such as caustics and surface wave focusing, among others. We present techniques for adaptively updating the channel braids and their overlap patterns to reflect the temporal evolution of the shallow water acoustic channel. We evaluate the performance of proposed morphological channel estimation technique in terms of the normalized prediction error and computational time. Results based on numerical channel simulations based on diverse oceanic and experimental conditions as well as experimental field data from the SPACE08 experiment will be presented.
Dimensionality reduction of cross-spectral density matrices using diffusion map projections
Authors: Finette Steven I.
Published: December 2020

Cross-spectral density matrices (CSDMs) constructed for matched-field source localization in an ocean waveguide are both Hermitian and positive semi-definite, allowing them to be interpreted in a non-Euclidean geometric framework as “points” in a Riemannian manifold. This abstract matrix representation can be used to construct distance metrics on the manifold, and distances between pairs of such matrices provide a measure of similarity between the true source CSDM and various replica CSDMs. With this geometric interpretation, the shortest “distance” between pairs of source/replica CSDMs represents an estimate of the source location obtained from acoustic field amplitude and phase acquired on a vertical array [Finette and Mignerey, JASA 143 (2018)]. In this presentation, visualizations of CSDM manifolds obtained from simulated acoustic fields propagating in an ocean waveguide with internal wave-induced variability are illustrated to gain insight into this approach to passive source localization. Since the original manifold resides in a high-dimensional space determined by the number of sensors, manifold learning using diffusion maps is employed to reduce the dimensionality but constrained to retain the relative distance relationships among the CSDMs. The original manifold is projected down to three dimensions for visualization. [Work supported by the Office of Naval Research.]
A tiered, bio-inspired, modular framework for robust acoustic feature extraction
Authors: Taft Benjamin N.
Published: December 2020

Vertebrates separate audition into peripheral, brain-stem, and fore-brain stages. These stages are anatomically and theoretically separable, and our understanding of hearing has improved by analyzing them as such. Here, I outline a strategy for structuring acoustic feature extraction that is inspired by the tiered structure of the brain. The system aims to work online in close to real time, using a modest amount of memory and processing power. Another goal is to maintain a domain-appropriate conceptual connection between the features that we are measuring and the physical and/or biological processes that we are monitoring. We do this by breaking feature extraction into stages based on context. Some features will be useful across many contexts, or useful for distinguishing among contexts. We should extract those features at each time step of our analysis. Other features will only be relevant within specific contexts, so we should only spend computational resources on extracting them when they are relevant. This tiered computational strategy yields multiple points of introspection about the quantitative relationships between continuous features and discrete contexts. We can use quantitative introspection to analyze how well our modules generalize to other contexts, and to validate empirical models of how those contexts work.
Implementation of a microphone array for improved noise path estimation in a feed-forward active noise control system
Authors: Park Heui Young , Abes Daniel , Lawless Martin S. , Luchtenburg Dirk M.
Published: December 2020

Active noise control (ANC) systems detect incoming sound and generate an anti-noise signal to attenuate it through destructive interference. ANC systems are generally limited to low-frequency sounds because the sensors and actuators are close together, leaving insufficient time to react to high-frequency or impulsive sounds. To compensate, common applications, such as noise-cancelling headphones, rely on complete ear coverings to block out higher-frequency sound indiscriminately, potentially hindering communication and situational awareness. The present work proposes to use an external array of microphones surrounding the user to increase the distance between the sensors and the user to afford more time to generate anti-noise signals and provide better path estimation. Using time delay of arrival (TDOA), the array tracks the locations of the user and the noise sources in real-time. The ANC system uses a feed-forward Filtered-x Least Mean Squared (FxLMS) algorithm that adjusts the weights of the controller based on the TDOA path estimation instead of adapting the filters with an error microphone and feedback loop. Simulations of the proposed system and feedback FxLMS path estimation were conducted in MATLAB. Compared to the feedback FxLMS algorithm, the TDOA system yielded 11 ± 1 dB less root-mean-square error in the generated anti-noise signals.
Determining the range to marine mammals in the Northern gulf of mexico via bayesian acoustic signal processing
Authors: Leftwich Kendal , Drouant George , Ioup Juliette W.
Published: December 2020

Being able to determine the range or distance to an object from its acoustic signal is a key component in tracking the object. We will apply concepts from the Bayesian processor (Kalman filter) as well as known environmental aspects to LADC-GEMM underwater passive acoustic data: sperm whales, beaked whales and dolphins in the northern Gulf of Mexico. The Bayesian processor has had applications in chemical processing, navigation, ocean acoustics, seismology, and tracking, among others. We will use a modified version of the Kalman filter with data from a single hydrophone to determine the most-probable range of the marine mammal from the hydrophone. We will use such aspects as the geometry of the region, the depth of the hydrophone, the range of possible detection, the structure of the click and other factors to restrict the possible locations of the marine mammal source. From this, we can determine a three-dimensional shell of most probable locations for the marine mammal.
Appreciations of Jiri Tichy as mentor, educator in the 1980's
Authors: Kahn David
Published: December 2020

Jiri Tichy was leading Penn State's Graduate Program in Acoustics in 1980 when I applied to the program. He directed my studies there and was my advisor for my master's thesis on the topic of architectural acoustics. His mentoring continued past my graduation from the program, 3 years later until my master's thesis research topic was published in the Acoustical Society of America's journal in September 1986. Having been in the field of architectural acoustics for over 35 years since graduating his program, that perspective has helped my appreciation for what a gifted mentor and educator he was. During this presentation, I will share some of the highlights of my tutelage under Jiri Tichy.
Acoustic and mechanical characterization of gelatin methacryloyl scaffolds for tissue engineering applications
Authors: Anderson Megan , Osborn Jenna , Rao Raj , Zhang Lijie Grace , Sarkar Kausik
Published: December 2020

Gelatin methacryloyl (GelMA) is a highly biocompatible, biodegradable material and a 3-D printable option for constructing tissue engineering scaffolds. Improved material characterization of GelMA is necessary to optimize preparation techniques, evaluate tissue similarities, and validate tissue engineering potential. Conventional testing methods are through destructive, one-time measurements, yet nondestructive tests are desired for evaluating long-term changes. In the present study, ultrasound techniques were utilized to measure mechanical properties of GelMA tissue scaffolds. Varying concentrations of GelMA and ultraviolet light curing time produced scaffolds with a range of material properties. Ultrasound pulse-echo techniques were used for a non-destructive acoustic characterization procedure, and parameters including speed of sound, acoustic impedance, and attenuation coefficient were measured. To further evaluate the material properties of the scaffolds, compression testing was performed. Physical parameters of GelMA were found to be similar to those of native tissues, demonstrating that GelMA scaffolds are biomimetic. The impact of GelMA concentration and curing time will be discussed to inform the selection of preparation parameters for specific tissues. Acoustic characterization proves to be a promising technique for evaluating the structure and function of the scaffolds and could serve as an indicator of tissue scaffold health while providing real-time monitoring in vivo.
Non-thermal effects of ultrasound are selectively induced during a critical window of collagen self-assembly
Authors: Norris Emma G. , Majeski Joseph B. , Wayson Sarah E. , Coleman Holly , Choe Regine , Dalecki Diane , Hocking Denise C.
Published: December 2020

Type I collagen is a self-assembling fibrillar protein widely used in tissue engineering. An established paradigm utilizes ultrasound exposure during the fluid-to-gel phase transition of neutralized collagen solutions, producing site-specific changes in collagen fiber organization via both thermal and non-thermal acoustic mechanisms. In the present study, we investigated the temporal dependence of ultrasound bioeffects with respect to the progression of collagen assembly. Collagen solutions (0.8 mg/ml) were exposed to ultrasound (CW, 7.8 or 8.8 MHz, 0–10 W/cm2) for 5 min during three distinct stages of collagen self-assembly, which were monitored via both temperature and optical turbidity measurements. Assembly rate was manipulated by adjusting the collagen pH and the temperature at which acoustic exposures were performed. The results identify a critical window during which ultrasound exposure produces radially aligned collagen fibers via a non-thermal acoustic mechanism. This window coincides with a stage of collagen polymerization during which nanofibrils associate laterally into microfibril bundles, and a simultaneous increase in the acoustic absorption coefficient. These findings raise the possibility that ultrasound exposures of self-assembling collagen biomaterials in a point-of-care clinical setting can be timed to preferentially induce either thermal or non-thermal bioeffects, thereby enhancing the efficacy of therapeutic ultrasound for regenerative medicine applications.
Polymers in high-intensity focused ultrasound fields
Authors: Peng Kaiyuan , Shahab Shima , Mirzaeifar Reza
Published: December 2020

High-intensity focused ultrasound (HIFU) is a promising stimulus that has received extensive attention during the past two decades due to numerous advantages of this technology when compared to the conventional methods. For HIFU-responsive polymers, their applications could be extended to controlled drug delivery, soft robotics, and flexible electronics. In this work, experiments show that polymers heat up in a different manner when they are subjected to HIFU, compared to the case they are subjected to heat sources directly. However, the origins of this difference are still entirely unknown. To further investigate, molecular dynamics (MD) simulations are performed to study the thermal effect of polymers induced by HIFU. We found the difference in the macroscale response of polymers subjected to HIFU strongly depends on the polymer chains, composition, and structure. The frequency-dependent viscoelasticity, measured by stress-strain phase lag, the reputation motion of the chains, and the vibration-induced local mobility, quantified by the root mean square fluctuation (RMSF) contribute to the observed difference in the HIFU-induced thermal effects. The simulation results show a good accordance with the experiment qualitatively, and provide the fundamental mechanism for designing and optimizing stimuli-responsively polymeric devices. [Work supported by: this work was supported by NSF Grant No. CMMI-2016474.]
Investigation of optimization techniques on structural-acoustical shaped concrete slabs in buildings
Authors: Broyles Jonathan , Shepherd Micah , Brown Nathan C.
Published: December 2020

Computational tools have become integrated into design practice at the building scale and component scale. While there has been a resurgence of optimization techniques in room acoustics, research has been limited on utilizing optimization techniques on building components, such as a building's structural floor. Quality design solutions must be found at the component scale to accommodate for increased urbanization, environmental concerns, building utilization, and the well-being of the occupants, especially in relation to the tenants' acoustic environment. This presentation will discuss the use of several design space exploration and optimization approaches to generate and consider multiple permutations of shaped concrete floor designs. The shape of the ribbed slab will be varied in order to improve both the embodied energy of the concrete slab, which is proportional to mass, as well as the sound transmission class (STC). Three computational techniques (Latin Hypercube Sampling, multi-objective evolutionary optimization and constrained optimization) will be used to determine trade-offs in the design. The advantages and disadvantages of each technique will be highlighted with respect to the trade-off between reduced mass and improved STC. Finally, the importance of model resolution will be discussed in early design space exploration and optimization procedures.
MEMS microphones in commercial applications and beyond: Technology trends in the next decade
Authors: Pedersen Michael
Published: December 2020

Since the initial introduction in the early 2000s, MEMS-based microphones have grown to become the preferred choice in a large range of commercial applications. This growth has been driven by continuous improvements in transduction performance, product consistency, and device ruggedness to meet ever more stringent application requirements. The emergence and rapid development/growth of small wearable devices, has given rise to a new set of possibilities and requirements for the acoustic transducer. In these applications power consumption, size, and ingress immunity are of major importance. While existing MEMS microphone topologies are being adjusted and adopted for this purpose, there are also opportunities for different structures and new operational schemes to further enhance product performance. In the area of acoustic performance, MEMS microphone technology has reached some fundamental barriers, particularly on size, at which entirely new approaches will be necessary to change the performance/size equation. In this presentation, a review will be given of MEMS microphone technology and how it got us to where we are today. In addition, projections will be shared on where the technology might go in the future where fully sealed, high performance, micro-scale devices are imaginable.
Flipping the lab: Portable automated rapid testing (PART) systems for psychological acoustics
Authors: Gallun Frederick J.
Published: December 2020

The second decade of the 21st Century has seen the rise of consumer technology capable of producing auditory signals at a level of precision only available to laboratory scientists and engineers just a few years earlier. This has allowed researchers to “flip the lab” and begin creating testing systems that can be taken to the participants rather than bringing the participants to the systems. This talk will describe how freely available tablet and smart-phone applications, low-cost portable hearing-aid development systems, and programmable virtual reality systems are all poised to change that way that research is conducted. Discussion will include the research that has been done validating the existing approaches and describing those guides to best practices that exist (or need to). Finally, this talk will discuss the ways that such approaches are essential aspects of lowering barriers to who can be involved in clinical research, both as experimenters and as participants.
Quantifying the cumulative effects of sustained excitation on the vibrational response and radiated sound of violins: Preliminary results
Authors: Adkisson Kourtney , Piacsek Andrew A.
Published: December 2020

There is a widely accepted belief among luthiers and performers that consistent playing of stringed instruments, especially in the violin and lute families, is associated with improved sound and playability. Because it is thought that a new instrument needs to be played for some time in order to achieve its performance potential, many luthiers “pre-vibrate” new instruments before they are sold or delivered to customers. Very few studies have been performed to investigate the effect of artificial stimulation of new stringed instruments and the phenomenon of “playing-in” is still poorly understood. A long-term project underway at Central Washington University seeks to measure changes in vibrational and acoustic response that can be attributed to sustained mechanical stimulus. Three new sibling violins (same model and month of manufacture) were recently acquired: one is a control, while the other two will be mechanically excited at the bridge with a broadband signal, each with a different amplitude, continuously for several months. Prior to initiating the sustained excitation, a thorough study was conducted of the variability and uncertainty in measurements of the vibrational and acoustic response of each violin; this will serve as a baseline for interpreting the significance of subsequent changes.
Resonant ultrasound spectroscopy of cylindrically shaped sample of made of Ni-containing metallic glass alloy
Authors: Svitelskiy Oleksiy , Suslov Alexey , Duggins Danielle , Lee David , Siaw Kristen
Published: December 2020

Among different methods for determining elastic constants of a material, a special place belongs to the resonant ultrasound spectroscopy (RUS), as to a fast and non-destructive technique. We use a home-made RUS spectrometer to investigate the elastic properties of Ni71.5Cr5.6Nb3.4P16.5B3, a bulk metallic glass alloy (Ni-BMG). The sample was made by a counter-gravity suction casting technique and has shape of a cylinder. Modeling the measured spectrum of acoustic resonances for the sample in its cylindrical geometry was done with finite element analysis (FEA). FEA gives a longitudinal modulus (C11) of 300 GPa, and a Young's modulus (C44) of 50 GPa +/−5%. The determined values we verify by ultrasound pulse-echo technique, and compare them with the literature data for other Ni-bearing bulk metallic glass alloys. [This work was partially supported by NSF DMR award number 1709282. National High Magnetic Field Laboratory is supported by NSF/DMR-1644779 and the State of Florida.]
Von Karman spatial correlation functions for modeling ultrasonic scattering in metallic media
Authors: Arguelles Andrea P.
Published: December 2020

In recent years, ultrasonic scattering has been studied as a potential method for nondestructive microstructure characterization in polycrystalline media. In order to invert microstructural data from ultrasonic data, analytical models of wave propagation and material statistics are generally employed. The microstructure statistics are frequently represented by spatial correlation functions (SCFs), which describe how microscopic variables at random positions are correlated (e.g., elastic stiffness). In polycrystalline media with statistically isometric crystallites, SCFs are defined as the probability that two randomly chosen points lie within a single crystallite (or grain). This work evaluates the suitability of common forms of the SCF in capturing the statistics of realistic microstructures in the context of ultrasonic scattering measurements. In addition, we introduce the von Karman SCF, frequently used in seismic wave propagation studies, as a potential alternative for metallic components with increased microstructural complexity. In the macroscale, the material systems are assumed to be statistically isotropic, and the microstructural differences focus on the morphology of the grain structure.