bluuebunny/crossref_metadata_2025 huggingface dataset:
A Model Reference Adaptive Control Framework for Uncertain Dynamical Systems With High-Order Actuator Dynamics and Unknown Actuator Outputs
Authors: Gruenwald Benjamin C. , Dogan K. Merve , Yucelen Tansel , Muse Jonathan A.
Published: November 2017

As it is well-known, the stability properties of model reference adaptive controllers can be seriously affected by the presence of actuator dynamics. To this end, the authors recently proposed linear matrix inequalities-based hedging approaches to compute the stability limits of model reference adaptive controllers in the presence of a) scalar actuator dynamics with known outputs, b) scalar actuator dynamics with unknown outputs, and c) high-order (linear time-invariant) actuator dynamics with known outputs. The common denominator of these approaches is that they have the capability to rigorously characterize the fundamental stability interplay between the system uncertainties and the necessary bandwidth of the actuator dynamics.

Building on these results, the purpose of this paper is to extend the recent work by the authors to the general case, where there exist high-order actuator dynamics with unknown outputs in the closed-loop model reference adaptive control systems. For this purpose, we propose an observer architecture to estimate the unknown output of the actuator dynamics and use the estimated actuator output to design the linear matrix inequalities-based hedging framework. Remarkably, with the proposed observer, the sufficient stability condition in this case of unknown actuator outputs is identical to the case with known actuator outputs that was established in the prior work by the authors. Therefore, a control designer can utilize the proposed framework for practical applications when the output of the actuator dynamics is not measurable, and hence, unknown (e.g., in hypersonic vehicle applications). An illustrative numerical example complements the proposed theoretical contribution.
A Regenerative Hydraulically Assisted Turbocharger System Model
Authors: Zeng Tao , Upadhyay Devesh , Zhu Guoming
Published: November 2017

A regenerative hydraulically assisted turbocharging system is introduced. A systematic modeling approach for the engine air-path influenced under the influence of the RHAT system is discussed. The proposed modeling approach adopted seeks to reduce model complexity by introducing simple parametric relationships between corrected performance measures and allows smooth extrapolation beyond available hydraulic turbine and pump maps. A lumped parameter model of the hydraulic system is presented. Model validation results are presented for an FTP-75 cycle.
Easy-to-Use 3D Printer for Fabrication of Biological Scaffolds
Authors: Armstrong Ashley , Alleyne Andrew , Wagoner Johnson Amy
Published: November 2017

3D printing is a diverse field, in particular for biological or bioengineering applications. As a result, research teams working in this area are often multidisciplinary. A (bio) 3D printer in this research environment should balance performance with ease of use in order to enable system adjustments and operation for all machine users from a wide range of disciplines. This work presents results in the development of an easy-to-use fabrication system capable of producing rectilinear bone scaffolds. Common motion control problems, which are barriers to ease of use, are addressed and implemented in a way that researchers outside of the controls field could easily understand. A dynamic model of a 3-stage position system for bone scaffold fabrication is presented. Further, control design for a feedforward plus feedback controller and a user-friendly ILC feedforward compensator is outlined. The ability of the (bio) 3D printer to print bone scaffolds and the effectiveness of the control architecture is demonstrated.
Multilevel modeling and regression of community annoyance to transportation noise
Authors: Wilson D. Keith , Pettit Chris L. , Wayant Nicole M. , Nykaza Edward T. , Armstrong Chandler M.
Published: November 2017

A multilevel (hierarchical) model is devised that separates noise tolerance into variations occurring at the levels of individual listeners and communities. This approach successfully describes the characteristics of real community transportation noise surveys, with the individual- and community-level variations producing distinct statistical signatures, both of which are evident in the surveys. Predictions are provided for quantities such as the probability of annoyance based on the observed noise level and statistical parameters characterizing the community tolerance. Regression analyses are performed using a multilevel, generalized linear model, which provides an appropriate generalization encompassing both no pooling (separate community-by-community analysis) and full pooling (all communities together) of survey data, and enables noise tolerances and their variations at the individual and community levels to be distinguished and quantified. Variations in individual tolerance and sound exposure within communities are found to be larger than variations in tolerance between communities; however, the variations between communities are still significant and observable. Analysis of multiple types of transportation noise with the multilevel model indicates that tolerance is highest for railway noise with low vibrations, followed by roadway noise, airport noise, and railway noise with high vibrations, as consistent with previous studies.
Modeling community noise impacts from launch vehicle propulsion noise
Authors: James Michael M. , Salton Alexandria R.
Published: November 2017

Commercial space is an emerging and evolving market as evidenced by the vast array of launch vehicles under development as well as the growing number of active and proposed launch sites. Federal Aviation Administration regulations require all new spaceports and launch vehicles to acquire a license. Part of the application process requires an environmental review to address the potential noise impacts to the environment and local communities. Accurate predictions of noise exposure from launch vehicles require models that have been validated over a range of vehicle types, operations, and atmospheric conditions. A high-fidelity launch vehicle simulation model, RUMBLE, has been developed to predict community noise exposure from spaceport launch, reentry, and static rocket operations. RUMBLE implements industry standard modeling practices to efficiently compute sound pressure level time histories, maximum levels, and sound exposure levels using the vehicle’s engine parameters and geo-referenced source/receiver definitions. An overview of RUMBLE’s underlying physics and the results of initial validation efforts (using multiple full-scale launch measurements) will be presented.
Methods for measuring the vibratory response of the ground
Authors: Phillips James E.
Published: November 2017

A draft American National Standards Institute (ANSI) standard on “Methods for Measuring the Vibratory Response of the Ground” is nearing completion for review. This standard is being developed in parallel with a separate draft standard on “Methods for the Prediction of Ground Vibration from Rail Transportation Systems.” The intent of both documents is to standardize methods that were initially developed more than 30 years ago and adopted by the Federal Transit Administration. This paper will outline the topics in the draft standard, the measurement, and analysis techniques typically associated with the methods described, and how the draft standard relates to existing standards pertaining to measuring transfer mobility.
Tracking time varying multipath phase at very low signal to noise ratios
Authors: Gendron Paul J. , Desiltes Hanna , Silva Jacob L.
Published: November 2017

Diverse acoustic environments support multipath propagation. Estimating the arrival gains allows receiver structures to coherently combine acoustic energy for improved reception. In the case of mobile acoustic sources and receivers or dynamic boundaries, the amplitudes and phases of those arrivals are time varying such that estimation is made more difficult and typically entails some kind of phase tracking loop. This can be challenging as trackers are often formed as recursions in time employing previous observations to predict the phase at present, updating each phase estimate with the most recent observation. At extremely low SNR, recursive tracking can suffer loss of lock. Since a great deal of information about the instantaneous phase is contained in observations before and after it is judicious to seek estimators that exploit all of the observations in the signalling interval to infer the time varying response phase. Presented here is a scheme for simultaneous time varying phase estimation from the reception of a long duration, high time-bandwidth product transmission. In this approach, the phase process is derived from a minimum mean square error estimate of the sparse acoustic time varying response under an assumed sparse mixture model prior over Doppler and frequency. Demonstrations in shallow water at less than −12 dB received signal to noise ratio are presented.
Modelling broadband scatter from periodic sea surfaces
Authors: Richards Edward , Hodgkiss William S. , Song Hee-Chun
Published: November 2017

Surface waves are the primary source of short time-scale variation of the channel impulse response in underwater transmission scenarios when source and receiver positions are fixed. This study proposes an exact method for modeling the single surface bounce path of the channel impulse response, which contains most of short time-scale effect. This method is designed for one dimensional, periodic wave profiles, and solves the scattering problem as a series of motionless surfaces. To create a time series for each surface, the proposed method solves the Helmholtz equation at many frequencies, performing three steps at each frequency. First, the point source is decomposed into a series of plane waves, each of which scatter from the surface at a finite number of Bragg angles. Second, the amplitudes of these discrete scattered plane waves are found with an exact method. Finally, the surface response for a three-dimensional point source is recovered with a plane wave synthesis of these scattered plane waves. The results of this study are intended as a reference to inform the interpretation of surface scattering results from more common underwater acoustic models.
Comparing the binaural recordings of 22.2- and 2-channel music reproduced in three listening rooms
Authors: Kim Sungyoung , Ashok Madhu , King Richard L. , Kamekawa Toru
Published: November 2017

A room interacts with sound sources. It alters both timbral and spatial impression of produced and reproduced sound field(s), and affects the overall sonic experiences. In this study, we approached the room-induced effect in the context of an immersive audio rendering, and investigated a relationship between room acoustics and audio reproduction formats. First, three classical music pieces were recorded and mixed optimally for the 22.2- and 2-channel reproduction formats. Subsequently, we generated a set of binaural responses to each of 22.2- and 2-channel reproduced music at three distinct listening rooms (varying dimensions and reflecting surfaces). Eleven listeners participated in a listening experiment; they compared two randomly selected binaural stimuli and rated perceived dissimilarity. The collected ratings were analyzed through the individual differential scaling (INDSCAL) to determine a perceptual space of the stimuli. The results show that (1) the listeners perceived the stimuli differences through two factors-the reproduction format (dimension 1) and the listening room (dimension 2); and (2) the room-induced perceptual difference was less dominant for the listeners compared to the format-induced one. The importance of each dimension was determined via the goodness of fit of the INDSCAL results as follows: Dimension 1-0.7138 and Dimension 2-0.1649.
Soundscape components in a shallow-water zone off the coast of Goa
Authors: Madhusudhana Shyam Kumar , Chakraborty Bishwajit
Published: November 2017

Underwater acoustic data were collected around Grande Island off the coast of Goa, India using moored autonomous recording equipment during March 2016 and March 2017 for four and ten days, respectively. The study site, a shallow-water area in the vicinity of the Zuari river estuary and in proximity of a major shipping port, is presumed to lie along cetacean migration routes. Two different locations were chosen for data collection during each year—a reef site and an off-reef site. All four datasets were dominated by circadian choruses of fish and snapping shrimp. Fish species that were found to contribute significantly to the soundscape includes terapontidae, toadfish, and sciaenidae. Other biological contributions included vocalizations from cetaceans. For example, beaked whale clicks were observed in the 2016 recordings and humpback whale vocalizations were observed for six days in the 2017 recordings. Anthropogenic influence in the soundscape remained low during both years and the only contributing sources were sporadic vessels passing in the vicinity. Given the low measured levels of anthropogenic contribution, the findings of this study could be used as a baseline for performing impact assessments during any future offshore operations in the region.
Lognormal bubble size distributions
Authors: Caruthers Jerald W.
Published: November 2017

In the study of oceanic bubbles based on empirical acoustics, the distributions among the sizes are typically represented by power laws with negative slopes as convenient descriptors of data in log/log format. However, power laws do not address the fact that as bubble sizes approach zero their numbers must approach zero. Multiple power laws, including a horizontal segment preceded by a positive power-law segment and followed by the expected negative power-law segment, have been used to recognize and mitigate this problem. Although not universally adopted as yet, several acoustic researchers have suggested that at least some oceanic bubble distributions are more appropriately represented by lognormal distributions. In 1941, A. N. Kolmogorov used the 1922 work of L. R. Richardson concerning a stochastic downward cascade of random sizes of turbulent vortices that asymptotically result in lognormal distributions of vortices. This current paper uses such a cascade of vortices to begin a downward cascade of bubbles sizes causing cascading shear forces on large bubbles that were created by breaking waves. In combination with this decreasing effect of turbulent shear on these fragmenting bubbles, the downward cascade of bubbles sizes overlaps and continues with a strengthened partial-pressure effect on ever increasing surface tension caused by their diminishing sizes. Issues associated with this approach, such as summing lognormal generators and intermittency, will be discussed.
Simulation of guided waves in layered fluid/viscoelastic/poroelastic media using semi-analytical finite element method
Authors: Nguyen Vu-Hieu
Published: November 2017

Understanding of the ultrasound transmission in functionally graded structures materials is of great interest in many engineering applications such as geophysics, biomedical diagnostics, aircraft, and automobile. This paper will present a computational method and its implementation procedure to study the wave propagation problem in multilayer structures made from a combination of fluid, anisotropic viscoelastic, and poroelastic materials. The poroelastic material is described by using the Biot theory. The developed approach is based on the Semi-analytical Finite Element Method (SAFE), which only requires the discretization of the cross-section of the structure. For the finite element solver, high-order spectral element has been used, showing a significant improvement of the computational efficiency compared to the use of conventional high-order elements. Numeral validation in both time and frequency domains show that the proposed approach is efficient to investigate the transient response as well as the dispersion of layered media. Some results in the context of quantitative ultrasound axial transmission techniques for assessing properties of cortical long bones will also be presented.
Vowel mergers in the American South
Authors: Foster Shawn C. , Stanley Joseph A. , Renwick Margaret E.
Published: November 2017

This study investigates the occurrence of a series of vowel mergers in the English of the Southern United States. Investigated mergers include the pin-pen merger, which may be considered characteristic of Southern English, as well as the cot-caught, pull-pool, fill-feel, and cord-card mergers, which are less strongly identified with the region. First and second formant values of over 300,000 vowel measurements from 41 speakers were automatically extracted from.wav files contained in the Digital Archive of Southern Speech (DASS). Vowel distributions were statistically analyzed via Pillai scores, Euclidean distance, and mixed-effects modeling to determine to what degree, if any, the speakers participate in these mergers. Previous studies on vowel merger in the United States have typically classified speakers into discrete “merged” or “unmerged” categories, often relying on speaker or listener judgments to do so. The richness of the acoustic data and high number of tokens available for this study allow speakers to instead be classified along a spectrum, where they are described by “degree of merger” rather than binarily. The results in turn provide new perspective on how Southerners have participated in or resisted dialectal changes that have shaped American English from the late 18th through the mid-20th century.
Flow visualizations using electronic speckle pattern interferometry
Authors: Coyle Whitney L. , Moore Thomas
Published: November 2017

Imaging air flow in and around a musical instrument is a difficult task, but it can be important for understanding the physics associated with sound production as well as verifying the accuracy of computer simulations. Particle image velocimetry (PIV) has been successfully used to image air flow, but it requires expensive equipment, extensive technical expertise, and sophisticated software. Furthermore, PIV is usually restricted to observing only a small area of the flow. As an alternative to PIV, we demonstrate a method based on electronic speckle pattern interferometry that allows large-area real-time imaging of air flow using minimal optical equipment.
A metamaterial design method applied to topologically protected mechanical metamaterials
Authors: Matlack Kathryn , Serra-Garcia Marc , Palermo Antonio , Huber Sebastian D. , Daraio Chiara
Published: November 2017

Mass-spring models provide a straightforward way to describe complex dynamic behavior of mechanical systems, such as topologically protected and backscattering-free surface phonons. Such discrete models also provide a means to translate these properties, based on the unique class of electronic materials of topological insulators, to the mechanical domain. This talk will discuss a systematic design process to take such a mass-spring model and implement its functionality directly into a metamaterial. The design method uses combinatorial searches plus gradient-based optimizations to determine the configuration of the metamaterial’s building blocks that replicates the behavior of the target mass-spring model. A key aspect of the design method is the use of “perturbative metamaterials”—i.e., metamaterials with weakly interacting unit cells. The weak coupling enables the design space to be divided into smaller sub-spaces that can be independently tuned, which results in an exponential speed-up of the design process. It also allows us to isolate the interactions between vibrational modes of its unit cells within the frequency range of interest, simplifying the inverse problem. The design method is illustrated through the example of engineering a 2D mechanical metamaterial that supports topologically protected and defect-immune edge modes, directly from the mass-spring model of a topological insulator.
Active acoustic metamaterials using sensor-driver architecture
Authors: Popa Bogdan Ioan
Published: November 2017

Acoustic metamaterials can, in principle, overcome the fundamental limitations of passive structures and can enable novel applications that are hard or impossible with passive media. However, active acoustic metamaterials remain elusive, and the few implementations going beyond basic material parameter tunability lag significantly behind the true potential of active media. We will present a design method that results in active metamaterials whose acoustic response is electronically programmed to cover a very large range of non-linear acoustic responses. Specifically, metamaterials obtained with this approach can be configured to have almost any second and higher harmonic response, making them very effective and versatile non-linear acoustic media. We demonstrate experimentally this design methodology in an application in which an acoustically thin metamaterial funnel responds to incident sound waves by producing collimated second harmonics. Past demonstrations of this type of active metamaterials will also be briefly reviewed.
Using oropharyngeal articulation to compensate for nasalization: Acoustic and perceptual evidence
Authors: Rong Panying , Kuehn David P. , Shosted Ryan
Published: November 2017

A variety of oropharyngeal articulatory differences have been identified between oral and nasal vowel pairs in different languages, which either enhance or reduce the acoustic effects of nasalization. The aim of this study is to simulate oropharyngeal articulatory adjustment strategies to maximally compensate for the acoustic effects of nasalization. Two articulatory models were used for the simulation—one speaker-independent (SI) model and one speaker-dependent (SD) model. The results suggested that (1) the oropharyngeal articulatory strategies generated by both models effectively reduced the acoustic effects of nasalization on the low-frequency spectrum of the vowels; and (2) the oropharyngeal articulatory strategies generated by the SD model provided a better compensatory effect in the spectral region of F2 and higher formants compared to the strategies generated by the SI model. Moreover, a comparison of nasality ratings of the synthetic nasal vowels with and without oropharyngeal articulatory adjustments showed a significant reduction of nasality following oropharyngeal articulatory adjustments. These findings provide acoustic and perceptual evidence in support of motor equivalence. With further research on other speech sounds and the temporal pattern of nasalization warranted, the findings might have potential clinical implications for reducing hypernasality in persons with resonance disorders.
Articulatory correlates of phonemic and coarticulatory nasalization
Authors: Barlaz Marissa , Liang Zhi-Pei , Sutton Brad
Published: November 2017

Phonological theory distinguishes nasal and oral vowel counterparts by velopharyngeal port opening, neglecting other phonetic differences between phonemic and coarticulatory nasalization. Recent articulatory work provides evidence of oropharyngeal distinctions, in addition to velic lowering. This study (12 Brazilian Portuguese speakers) uses real-time MRI to investigate oropharyngeal differences between oral, phonemically nasal, and phonetically nasalized vowels /a, i, u/. Tissue boundaries in midsagittal vocal tract images were automatically detected to reveal each vowel repetition’s aperture function. Principal Components Analysis determined vocal tract regions responsible for the greatest variance in the data. Time-dynamic analyses of vocal tract area in these regions used smoothing spline ANOVA. Results show the tongue body and/or hyperpharynx as the most important articulators. For /a/, nasal vowels demonstrate wider hyperpharyngeal and narrower tongue body regions compared to oral vowels. For /u/, oral vowels show wider hyperpharyngeal and narrower tongue body regions. For /i/, nasal vowels demonstrate wider tongue body and narrower hyperpharyngeal regions. Nasalized vowels manifest apertures intermediate between oral and nasal vowels for /a/ and /u/, and similar to oral vowels for /i/. Results are largely in line with expected acoustic effects of nasalization, and demonstrate that phonetic differences exist between phonemic and coarticulatory nasalization.
Compressive spectral estimation methods using a noise reference
Authors: Douglass Alexander S. , Dowling David R.
Published: November 2017

Compressive beamforming methods have shown promise for use in high resolution direction finding and source localization. However, these methods often fail in scenarios with low SNR, particularly if only a few snapshots are available. The Spectral Estimation Method (SEM) (Blacodon and Elias, 2004, J. Aircraft 41 (6), 1360–1369) provides a means of source localization and source power estimation by minimizing the mean squares error between cross-spectral-density matrices of a measured signal and modeled signals at each location of interest. SEM With Additive Noise (SEMWAN) (Blacodon, 2011, Applied Acoustics, 72, 11–21) does the same but also utilizes the cross-spectral-density matrix of one or more noise references. In this presentation, the performance of a compressive version of SEMWAN is assessed for use in low SNR scenarios when the solution is sparse and a noise reference is available. Compressive SEMWAN is analyzed first using far-field, free-space simulations with varying SNR and multiple sources. Compressive SEMWAN is then applied to laboratory measurements taken with real noise sources at varying SNR and including some multipath propagation. The performance in each scenario is compared directly to conventional beamforming, a standard compressive beamforming method, and traditional SEMWAN. [Sponsored by NAVSEA through the NEEC.]
Bayesian-Maximum Entropy method applied to seabed geoacoustic models using broadband and narrowband acoustic measurements
Authors: Knobles D. P. , Wilson Preston S. , Hodgkiss William S. , Wan Lin , Badiey Mohsen
Published: November 2017

Conditional probability distributions P(H|D,M) are computed using a Bayesian-Maximum Entropy method applied to acoustic measurements collected during the Seabed Characterization Experiment in the spring of 2017. Marginal distributions are computed for both seabed geoacoustic and source parameter values. A prior range-dependent seabed model M is derived from CHIRP survey measurements made in 2015. The prior bounds of parameter values forming the hypothesis vector H are obtained from an extensive set of sediment core measurements made in the region. The acoustic data, D, were produced by small explosive and combustive sources and towed tonal sources. Two acoustic models are employed to sample the N-dimensional H space: Range-dependent parabolic equation RAM and a normal mode method that includes shear wave effects. The dimensionality of M is optimized via a Gaussian Mixture Model (GMM) and compared to the Bayesian Information Criterion (BIC) and the Akaike Information Criterion (AIC). [Work supported by Office of Naval Research.]
The measurement of muddy seabed properties using ambient noise coherence
Authors: Bevans Dieter A. , Barclay David R. , Buckingham Michael J.
Published: November 2017

The autonomous passive acoustic lander Deep Sound was deployed five times during the Seabed Characterization Experiment and collected ambient noise data on four hydrophones, arranged in a inverted “T” shape, with three spaced in the horizontal and two in the vertical. The lander was deployed with the bottom-most phones approximately 30 cm above the seafloor, recording over an acoustic bandwidth of 5 Hz–30 kHz. Pressure time series, vertical and horizontal noise coherence (directionality), and the local temperature and conductivity were recorded continuously for periods of 9 hours. Wind-driven surface ambient noise coherence was used to estimate bulk acoustic seabed properties. An analytical Pekeris-waveguide noise model was fitted to the data in order to determine the bulk sound speed, density, and frequency dependent attenuation in the bottom fluid half-space. [Research supported by ONR.]
Perceptual evaluation of a virtual acoustic room model
Authors: Vigliensoni Gabriel , Romblom David , Verge Marc-Pierre , Guastavino Catherine
Published: November 2017

Two experiments were conducted to perceptually evaluate a virtual acoustic room model implemented using a virtual microphone technique for the direct path and reflections, the image-source model for the reflection geometry and a Feedback Delay Network reverberator. Experiment 1 aimed to determine the best equalization profile for different room sizes. Anechoic recordings of 7 solo instruments were processed to generate 5 room sizes with profiles corresponding to 5 different absorption settings. Fourteen sound engineers and musicians were asked to rate the resulting stimuli in terms of how realistic each setting was for the instrument in that space. The highest ranked absorption setting for each room size was selected for Experiment 2 to investigate whether listeners could identify different rooms sizes across different instruments. Using a free sorting task, 15 musicians were presented with 7 different solo instruments in 5 different room sizes and asked to group them by type of space in which the instruments were performed. The analysis of the dissimilarity matrices indicates that participants were able to organize sounds by room sizes, but the two largest rooms tended to be clustered together. The results show that the virtual acoustic model is capable of rendering realistic room effects.
Room acoustics: Idealized field and real field considerations
Authors: Accolti Ernesto , di Sciascio Fernando
Published: November 2017

How is an acoustically diffuse field defined? To what extent are valid the equations of diffuse field theory? These are the questions addressed in this presentation. The answers are explained through more general theories, in turn explained with figures instead of formulae. The starting point is the idealization of diffuse sound field, from where the basic calculation tools used in architectural acoustics are derived. Then, we go through the physical-mathematical models of wave theory and ray theory assuming diffuse field simplifications and analyze the scope of diffuse field models. Wave models and ray models are presented in a simple format with visual support and reference to the underlying mathematical models. The criteria used to define a diffuse field in frequency domain as well as in temporal domain are analyzed. Finally, we present a review of several state of the art tools used to address the real cases when diffuse field cannot be assumed.
Calculating sperm whale lengths in the Northern Gulf of Mexico
Authors: Drouant George , Ioup Juliette W.
Published: November 2017

Sperm whales (Physeter macrocephalus) produce short duration acoustical clicks while diving to search for food, each click composed of several pulses. The time interval between consecutive pulses, the interpulse interval (IPI), can be used to estimate the length of the whale. IPIs have been estimated from whales of unknown orientation by processing several hundred clicks and averaging the results. In this work, discrete wavelet transforms and autocorrelation-based methods are used to obtain IPI estimates with improved consistency. The Littoral Acoustic Demonstration Center—Gulf Ecological Monitoring and Modeling (LADC-GEMM) project collected underwater acoustic data in the northern Gulf of Mexico during the summer of 2015. Results presented here are produced using data recorded by the LADC Environmental Acoustic Recording Systems (EARS) at the site closest to the BP oil spill. Calculated lengths can be compared to lengths from previous measurements as well as to future measurements in order to determine changes in average whale size, useful in determining population health. [This research was made possible by a grant from The Gulf of Mexico Research Initiative. Data are publicly available through the Gulf of Mexico Research Initiative Information & Data Cooperative (GRIIDC) at https://data.gulfresearchinitiative.org.]
Dolphin target detection processes investigation using finite element model
Authors: Wei Chong , Hoffmann-Kuhnt Matthias , Au Whitlow , Ketten Darlene R. , Ho Abel
Published: November 2017

Dolphins and porpoises use their sophisticated biosonar systems for targets detection, within a range of a few meters to about 200 m, there is not a better sonar on the planet. In this study, the high resolution computer tomography (CT) scan data were used to create the detecting click signal propagation models of Atlantic bottlenose dolphins (Tursiops truncatus) and harbor porpoise (Phocoena phocoena). The finite element methods (FEM) were used to simulate the processes of the clicks emitted from phonic lips and transmit to the water through animals’ heads. The biosonar beam forming in the nearfield and farfield including the amplitude contours were determined and compared to the prior measurement results. There were no evidences of convergence in the farfield, which were consistent with measurement results for Tursiops truncatus. Additionally, in a cross-modal matching experiments with Tursiops, we found that the accuracy of the successive match was significantly different when the following subjects with same shape were used (water-filled PVC pipes, air-filled PVC pipes, foam ball array, and PVC pipes wrapped by foam) the results of FE model shed some light on the reasons why the animal has significant difference in performances when detecting different targets in the experiments.
Engaging high school students in studying marine mammals observed near the BP oil spill
Authors: Leftwich Kendal , Ioup Juliette W. , Seab C. Gregory , Benit Simeon P. , Firneno Matthew
Published: November 2017

The Littoral Acoustic Demonstration Center—Gulf Ecological Monitoring and Modeling (LADC-GEMM) project partnered with Warren Easton Charter High School to analyze underwater acoustic data collected in the northern Gulf of Mexico during the summer of 2015, returning to sites previously surveyed by LADC. Results presented here are produced using data recorded by Environmental Acoustic Recording Systems (EARS) at the site closest to the BP oil spill. The aim of the outreach project described here is for high school students to learn to work independently using scholarly works to analyze and interpret data, as well as to communicate and collaborate in a professional environment. Various marine mammals have been detected, including sperm whales, beaked whales (Cuvier, Blainville, Gervais, and BWG), and dolphins (bottlenose, Rizzo). The numbers and types of marine mammals are possible indicators of the health of the area and the marine mammals around the oil spill. Changes will indicate possible future problems. [This research was made possible by a grant from The Gulf of Mexico Research Initiative. Data are publicly available through the Gulf of Mexico Research Initiative Information & Data Cooperative (GRIIDC) at https://data.gulfresearchinitiative.org.]
Evaluating hospital soundscapes to improve patient experience
Authors: Bliefnick Jay , Ryherd Erica E. , Jackson Rebecca
Published: November 2017

Patients routinely perceive hospital soundscapes to be poor when rating their experience on HCAHPS (Hospital Consumer Assessment of Healthcare Providers and Systems) surveys administered after discharge. In this study, sound levels within five hospital units were correlated with HCAHPS noise perception survey data. Acoustic metrics including A-weighted equivalent, minimum, and maximum (LAEQ, LAMIN, & LAMAX) and C-weighted peak (LCPEAK) sound pressure levels, occurrence rate, and speech intelligibility index were evaluated in 15 patient rooms and 5 nursing stations. Average patient room LAEQ values within the five units ranged between 52 dBA and 61 dBA with speech intelligibility ranging from poor (<0.45) to marginal (0.45 to 0.75). The absolute minimum values measured within the patient rooms (LAMIN, LCMIN, & LZMIN) were found to be correlated with HCAHPS data and other metrics revealed trends consistent with patient perception. For example, the lowest rated unit also had higher occurrence rates, indicating this unit was louder more often. Ceiling type was also found to impact sound levels with LAEQ 5 dBA quieter on average for rooms utilizing acoustic tile ceilings. Taken as a whole, these results provide insight into acoustic metrics and design strategies which can ultimately be utilized to improve patient experience.
Noise in the recovery area of a large hospital
Authors: Beristain Sergio
Published: November 2017

A noise study was made in a very large government hospital which includes eight surgery rooms and a very large recovery area where patients are placed from as little as half an hour, either before or after a surgery, to about ten hours after some given surgery. In this area, physicians, nurses and bed moving personnel activity is almost continuous, and it has plenty of “Life Equipment” monitoring each and every patient. The noise measurements were concentrated in the recovery area, which is a very large room with very hard boundaries, that includes over 25 beds and aisle areas with no more than curtains separating them in order to allow for easy movement of rolling beds in and out from the surgery area and to the different specialty floors of the hospital. Results of these measurements are presented and commented.
Preliminary reports of New York city restaurant and bar noise levels via crowdsourced measurements show a low number of restaurants and bars suitable for various disabled communities, notably those with hearing loss
Authors: Farber Gregory
Published: November 2017

Noise causes hearing loss, tinnitus, and hyperacusis, and interferes with understanding speech for those with normal hearing and for those with hearing loss. Media reports document high sound levels in restaurants and bars, but accurate sound measurements are lacking. Noise pollution is an important health and social issue and the public needs a reliable way to determine whether certain venues are safe for auditory health and conducive to conversation. This is important for the disabled, the blind, the autistic and the hearing impaired, who include a large number of older Americans. This report is of sound level measurements in more than 2250 venues in New York City, using the novel SoundPrint smartphone app. The average sound level was 78 dBA in restaurants and 81 dBA in bars. These sound levels do not allow ready conversation, even for those with normal hearing and certainly not for those with hearing loss. There were variations in sound levels in restaurants in different neighborhoods and in different types of restaurants. The reported sound levels by venue managers generally underestimated actual sound levels. This report is a proof-of-concept study of crowdsourced sound measurements, which can provide valuable data for the general public and health officials.
Temperature and frequency dependent behavior of high intensity focused ultrasound (HIFU)-induced shear waves in a viscoelastic micellar fluid
Authors: Dayavansha E. G. Sunethra K. , Labuda Cecille , Mobley Joel
Published: November 2017

Wormlike micellar (WM) fluids, which flow when subjected to long term stresses, are mechanically viscoelastic over shorter durations. These fluids are birefringent under shear, allowing the study of shear wave propagation using both optical and acoustic modalities. In this work, the thermal and spectral behavior of ultrasonically generated shear waves in a WM fluid are studied. A fluid consisting of hexadecyltrimethylammonium bromide (CTAB) and sodium salicylate (NaSAL) combined in a 5:3 ratio is used in a 200 mM concentration. A high intensity focused ultrasound (HIFU) beam generates radiation pressure in the fluid and can induce shear waves of sufficient amplitude to be visualized optically when the beam is modulated. By pulsing the HIFU beam, a train of shear waves are generated which propagate laterally from the focal region. The temperature and frequency dependent behavior of the HIFU generated shear waves are correlated with the rheological and microstructural properties of the fluid.
Acoustic performance of phononic crystals for underwater coating applications
Authors: Sharma Gyani Shankar , Skvortsov Alex , MacGillivray Ian , Kessissoglou Nicole
Published: November 2017

Acoustic coatings on maritime vehicles can significantly reduce the transmission of machinery noise in the ambient marine environment as well as absorb external acoustic waves. In this work, the performance of two types of phononic crystals with steel backing is investigated for acoustic coating applications. The first type of phononic crystal comprises periodic voids embedded in a soft elastic medium. The second type of phononic crystal comprises hard scatterers arranged periodically in an elastic medium. The voids exhibit monopole resonance, leading to low sound transmission through the coating in a broad frequency range. In contrast, the hard scatterers exhibit dipole resonance which results in low sound reflection. The ratio of bulk to shear moduli of the elastic medium governs the monopole resonance, whereas the dipole resonance is governed by the ratio of the density of the scatterers to the density of the host medium. The effect of steel backing on the transmission side of the elastic medium results in high values of sound absorption attributed to Fabry-Perot resonance. The advantages and limitations of the two types of acoustic coatings are discussed.
Acoustic cloak by inverse design and gradient based optimization
Authors: Amirkulova Feruza , Norris Andrew
Published: November 2017

We present a gradient based minimization of the total scattering cross section (TSCS) from a set of cylindrical obstacles by incrementally repositioning them so that they eventually act as an effective cloaking device. The idea differs from earlier inverse designs that use topology optimization tools and generic algorithms. We use the optical theorem to define the position dependent TSCS in terms of the forward scattering amplitude for an incident plane wave. The gradient-based optimization algorithm reduces the TSCS by evaluating its derivative with respect to the cylinder positions and then perturbatively optimizing the position of each cylinder in the cloaking device while taking into account acoustic the multiple scattering between the cylinders. The method is illustrated by examples of sets of hard cylinders of uniform size.
Double-decorated membrane structure: Initial efforts towards real-time phase modulation
Authors: Ghaffarivardavagh Reza , Anderson Stephan , Zhang Xin
Published: November 2017

One of the fundamental challenges in the practical implementation of acoustic metamaterials science is the issue of tunability. To date, proposed acoustic metamaterial structures and devices suffer from narrow-band working frequency are typically passive structures. For example, with regard to phase modulation using metasurfaces, the tunability and capability of real-time phase modulation is critical in numerous applications ranging from biomedical ultrasound to acoustic communication. The study presented herein represents an initial step toward realizing acoustic metamaterials with real-time tunability intended for phase modulation applications. Herein, the double-decorated membrane structure (DDM) will be introduced, in which fundamental resonance of two membranes have been tailored to generate constructive interference, enabling phase modulation across a large range, while the amplitude variation has been mitigated. In this study, analytical and numerical investigations have been conducted to explore and optimize the design parameters. The proposed structure can be also used for the aim of low frequency sound energy harvesting in which the DDM structure will broaden the working frequency band and, consequently, enhance the energy conversion efficiency.
A new approach to generate local resonator for the application of acoustic/elastic metamaterials
Authors: Sang Sheng
Published: November 2017

In this paper, we proposed a type of locally resonator which works by introducing more than one vibration modes, and thus can provide a new approach to formulate acoustic or elastic metamaterial. Such new concept of resonator is fundamentally different from traditional translational and rotational resonators. The potential application and design of acoustic metamaterial based on this kind of structures are also studied both analytically and numerically. The acoustic metamaterial filter we developed has proved to have unique property that only allow the waves with specific frequency to pass while other waves will be attenuated. We also proposed a kind of plane wave lens which can transfer plane wave with uniformly distributed amplitude profiles into pure plane wave. With this novel resonator, the research and application regarding it are highly anticipated in the near future.
Distributional factors in Telugu sibilant production
Authors: Redmon Charles , Jongman Allard , Zhang Jie
Published: November 2017

Telugu is one of a small set of languages described as exhibiting three or more place contrasts among sibilant fricatives (less than 4% of languages in UPSID; Maddieson and Precoda, 1990). In a pilot study of alveolar, palatal, and retroflex sibilant productions in VCV sequences, Telugu speakers were found to show consistent inter-speaker variation in the production of the palatal sibilant, with half showing evidence (in production and perception) of a complete merger with the alveolar, and the other half showing evidence of a merger with the retroflex, and no clear demographic differences underlying the delineation of the two groups. Following up on this result, we present acoustic data from native speakers of Telugu recorded in Hyderabad producing words with the three sibilants in multiple vowel contexts, positions (CV, VC), and lexical neighborhood structures (with vs. without sibilant competitors in a second order neighborhood), focusing in the acoustics in particular on formant transition cues to palatal and retroflex places. This data are presented both to clarify the present state of the Telugu sibilant system and to explore what effect the lexical distribution of these sounds has on the acoustic feature mapping of the contrast.
Vocalic processes in Southern Ute
Authors: Kharlamov Viktor , Oberly Stacey
Published: November 2017

Most of the Native American languages are severely endangered and lack detailed phonetic descriptions. Our research aims to document the sound system of Southern Ute, a Numic language of the Ute-Aztecan family spoken by approximately 40 elders in southwestern Colorado, for which only basic impressionistic descriptions are available in the published grammar of the language (Givon, 1980). In this acoustic study, we focus on Southern Ute vowels. We analyze over 6,000 vowel tokens produced by 8 fluent speakers and present our findings on a variety of vocalic processes in Southern Ute, including positional allophony, vowel harmony, as well as phonetic aspects of lexical stress and durational differences related to the phonological length distinction.