bluuebunny/crossref_metadata_2025 huggingface dataset:
Ken Stevens' influence on aerodynamic models of fricatives
Authors: Shadle Christine H.
Published: May 2015

In the late 1950s, John Heinz, under Ken Stevens’ supervision, used a constriction in a duct to model fricatives, recording the far-field sound spectra. Ken elaborated the model over the next 15 years: The constriction’s location corresponded to place. The flowrate and constriction area were used to compute the Reynolds number, indicating the degree of turbulence of the flow; the pressure drop predicted the far-field sound. However, as I showed when Ken supervised my thesis in the 1980s, an obstacle downstream of the constriction created more turbulence noise, and was a better approximation to sibilants. It could still be modeled by a circuit analog with independent source and filter. Similar models of interdentals and palatals were not as successful; geometric details not included in the area function affected the acoustic output. Other limitations of early models include: circuit analogs use only the speed of sound, but the much-slower convection velocity plays a role in noise modulation in voiced fricatives; noise source changes during transitions are oversimplified; quasi-static modeling of fricatives excludes the noise produced by articulator movement. Ways of incorporating these mechanisms of fricative production in simple, conceptually powerful models are needed.
Non-Gaussian correlated process sampling for Bayesian cognitive target classification
Authors: Clark Grace A.
Published: May 2015

A cognitive signal processing system (for example, in radar or sonar) is one that observes and learns from the environment; then uses a dynamic closed-loop feedback mechanism to adapt the illumination waveform so as to provide system performance improvements over traditional systems. Current cognitive radar algorithms are designed only for target impulse responses that are Gaussian distributed to achieve mathematical tractability. Our research generalizes the cognitive radar target classifier to deal effectively with arbitrary non-Gaussian distributed target responses. Given exemplars of target impulse responses, our Bayesian illumination waveform design algorithm requires the ability to draw complex correlated samples from a target distribution specified by both an arbitrary desired probability density function and a desired power spectral density. This capability is realized using kernel density estimation and an extension of a new simple and efficient nonlinear sampling algorithm by Nichols et al. Simulations using non-Gaussian target impulse response waveforms demonstrate very effective target classification performance. We discuss practical issues with the application of the algorithms to real-world problems.
Underwater acoustics at the Johns Hopkins University Applied Physics Lab
Authors: Newhall Bruce K. , Jenkins James W.
Published: May 2015

The Johns Hopkins University Applied Physics Lab (JHU/APL) was founded in 1942. JHU/APL began research in underwater acoustics in 1970 and became known for full scale ocean testing. JHU/APL developed the first technique to accurately measure the shape of a towed array. Towed array testing culminated in 1991–1992 with the deployment of a 5 km aperture measuring signal coherence and beam noise statistics in the Pacific, Atlantic, and Mediterranean. In 1982, JHU/APL began investigations into low frequency (LF) active sonar. Initially, airguns and explosives were employed to measure bottom and surface scattering strengths. Then, tests with a stationary controlled source were conducted from 1986–1989, activating both stationary and towed receiver arrays. In 1989, JHU/APL outfitted the Cory Chouest, adding a two story back deck superstructure. The lower level housed a three aperture LF source array and long towed receiver array, while the upper story berthed 50 scientists and engineers. This ship conducted a series of measurements of scattering strengths of the ocean surface, bottom and volume from 200–1000 Hz. Today JHU/APL employs 5000 staff of which about 150 are scientists and engineers working in underwater acoustics. Studies have expanded from LF beginnings to the full spectrum of acoustic frequencies.
A history of the study of low frequency sound absorption in the sea—An active 50 years and it isn't over yet
Authors: Browning David G. , Simmons Vernon P. , Herstein Peter D.
Published: May 2015

In 1965, Thorp published a compilation of low frequency data from SOFAR propagation that indicated absorption below 10,000 Hz was greater than predicted. It was suggested this may be an artifact, but the data were shown to fit a 1 kHz relaxation mechanism. NUWC (formerly NUSC) began an extensive at-sea measurement program, ranging from Hudson Bay (jointly with Canadian DREP) to Lake Tanganyika, while several other laboratories obtained data in other oceans. Yeager and Fisher, using the T-jump method at the Case-Western Laboratory, determined there was a 1 kHz relaxation in seawater associated with boron. The data collected at-sea showed, however, a variation between ocean areas, notably values from the North Pacific were 1/2 those in the North Atlantic. This puzzled supporters and encouraged critics. At Scripps, Simmons and Fisher, using a resonating sphere, showed that the boron relaxation did indeed cause the absorption of low frequency sound. Browning and Mellen discovered the key to the at-sea variation was pH, and at NUWC Mellen confirmed this dependence in the laboratory using Simmons' sphere. This direct connection between low frequency absorption and ocean acidification has produced several recent papers on possible implications, and increasing global warming suggests an interesting future.
Validating side scan sonar as a fish survey tool over artificial reefs in the Gulf of Mexico
Authors: Bollinger Michael , Kline Richard
Published: May 2015

Artificial reef placements are becoming an important part of fisheries management strategies worldwide due to the loss of natural reefs, and in the Western Gulf of Mexico due to the scarcity of hard structures and vertical relief near shore, which are essential habitat for reef fish. Current visual survey techniques can be crippled by low visibility and unpredictable currents in the Gulf of Mexico, but hydroacoustics can provide a solution to these problems. This study focuses on using ground-truthed side scan sonar technology to determine fish community biomass. Through fish abundance surveys and in situ fish sampling, we developed a fish survey protocol using side scan sonar to quantify fish assemblages over artificial reefs. The effectiveness of this technology for management purposes was also demonstrated by comparing it with visual census methods.
Experimental investigation of individual musicians on tonal quality for saxophones and clarinets
Authors: Kinzer Charles E. , McDermott Walter C. , Cheyne Stanely A.
Published: May 2015

An experimental investigation designed to quantify the effects of individuals on the tonal quality of a given saxophone, mouthpiece and reed combination, as well as a clarinet, mouthpiece, and reed combination has been performed. Several musicians, using the same instrument of each configuration, played a single note from each of these instruments which was digitally recorded. A Fourier transform of the recorded waveforms was used to compare the frequency spectrum from each musician. The results of the comparison will be reported and discussed.
High order modal approximation techniques in the frequency domain
Authors: Wixom Andrew S. , McDaniel James G.
Published: May 2015

This paper presents high order modal methods that increase the accuracy of the standard modal truncation scheme with an emphasis on frequency-domain accuracy. The existing Mode Acceleration and Modal Truncation Augmentation methods are compared alongside a new interpretation utilizing the interpolating polynomial. This technique is motivated by taking limits of the modal sum, introducing a residual that appears as a Laurent polynomial. The results presented focus on the case when the frequency range of interest is in the middle of the system’s spectrum of eigenvalues, meaning that at least some of the system’s natural frequencies lie below the lower bound of the frequency range. This case allows for a possible error in the Modal Truncation Augmentation method that is demonstrated here. Also, convergence properties of the methods are discussed and demonstrated.
Reduction of low frequency scattering from a cylindrical elastic structure using a multi-element multi-path design
Authors: Raudales David , Bliss Donald B.
Published: May 2015

Acoustic scattering of an incident plane wave off an elastic cylinder can be reduced by a multi-element multi-path (MEMP) design. Such a design replaces a single structural element with a system of elastically coupled subsystems, and utilizes the inherent mechanical properties of these coupled substructures, rather than damping, to tune its dynamic response. MEMP structures provide an innovative approach by increasing the number of wave transmission paths in this higher order system, thereby introducing physical phenomena not present in single element structures. Previous analytical and experimental work on vibration transmission in MEMP thin beams and shells demonstrates substantial wide-band attenuation. Current research considers the application of the method to underwater scattering from 2-D concentric thin cylindrical shells with azimuthally continuous radial elastic coupling. Modal decomposition of the thin shell equations is employed for mode-by-mode impedance matching between the Bessel function harmonics of the incident fluid planar wave and the polynomial functions of the mechanical structure. Quasi-static spring and mass impedance matching with the monopole and dipole modes ensures scattering reduction at lower frequencies, while novel resonance matching between the fluid and structure extends reduction into higher frequency ranges. Very promising results reveal possible applications in underwater naval submersibles.
The resonance of tapering spiral chambers
Authors: Pino Paula
Published: May 2015

This paper will explore the acoustical resonance of several cochlea-inspired sculptures (i.e., spiraling, tapering forms) made of glass, ceramics, and other materials. Each sculpture will function as an acoustic chamber and will be equipped with a loudspeaker and a “mouth” through which sound will pour out. Using frequency sweeps, feedback loops, reverb convolution, and acoustic prediction software I will measure the resonant and reverberant responses of these acoustic sculptures and compare them with analogous forms (e.g., animal horns, brass instruments, and mammalian cochlea). Special focus will be on the fundamental resonant frequencies and bass response of each shape. Extrapolation with these data will inform the production of larger, more architectural acoustic chambers modeled with similar spiraling geometry.
Navigating and developing acoustics research and curriculum within the Georgia Tech Center for Music Technology
Authors: Hsu Timothy
Published: May 2015

Acoustics at the Georgia Institute of Technology has primarily been based within mechanical engineering with various other faculty spread throughout the university. Within the last decade, the School of Music has developed an internationally recognized graduate degree program and research center in music technology. Since winning the Student Paper Award, my professional career has started in a unique faculty position within the School of Music at Georgia Tech, where my responsibilities are split between being an ensemble/choral conductor and an active member of the Center for Music Technology. One of the recent challenges is the development of an innovative undergraduate curriculum model that fuses music fundamentals, music technology, general musicianship, and engineering/computer science. At the graduate level, new coursework I have created has included a musical acoustics course for music technologists and a historical acoustics and modeling course. Additionally, developing a research track of acoustics within the confines of music technology has allowed my research to morph into musically related areas that my graduate research did not allow. Areas of current research include historical architectural acoustics, active temperament, synthesis, and noise control.
Teaching acoustics to people with non-scientific backgrounds
Authors: Jaramillo Ana M.
Published: May 2015

With a background in architecture, the author has spent some time developing curriculum for the teaching of acoustics to architecture, design, and music technology majors. Acoustic software is often employed as a tool for the understanding of acoustic concepts, especially helpful when teaching people with non-scientific backgrounds. Through her work with Anhert Feistel Media Group (AFMG), the author has had a chance to take a closer look at acoustic software and spend some time understanding the needs of acoustic simulation software users and learners.
Fate of methane gas bubbles emitted from the seafloor along the Western Atlantic Margin as observed by active sonar
Authors: Pillsbury Liam , Weber Thomas C.
Published: May 2015

A method for characterizing and quantifying marine methane gas seeps along the Western Atlantic Margin (U.S. East Coast) was developed and applied to 70 free-gas seeps observed by the R/V Okeanos Explorer in 2012 and 2013, in water depths ranging from 300–2000 m. Acoustic backscatter from an 18 kHz split-beam echo sounder and a 30 kHz multi-beam echo sounder provided information on the height to which the gas seeps rose from the seabed. Profiles of the depth-dependent target strength and scattering strength per unit depth were generated from the acoustic data. These profiles were compared to models of the evolution of rising bubbles in order to help constrain the ultimate fate of the bubbles. Of particular interest are comparisons of profiles for seeps originating below, at, and above the gas hydrate stability zone.
Diameter and density dependent target strength of submerged oil droplets measured by a broadband, high-frequency echo sounder
Authors: Loranger Scott , Weber Thomas C.
Published: May 2015

Over two million tons of oil enters marine environments from anthropogenic sources annually with severe environmental consequences. The most effective method of cleaning spills is to biodegrade them by dispersing the oil as droplets. However, the ultimate fate of dispersed oil in the environment is largely unknown. Acoustic remote sensing may offer a means by which to assess the quantity, characteristics, and ultimate fate of submerged oil droplets. To provide a foundation for this work, we have made a series of laboratory measurements using a broadband, high-frequency, calibrated echo sounder. Measurements of oil droplet frequency-dependent target strength were made in a 6 m deep tank of fresh water. Target strength was measured and compared to droplet size and density. Droplet size ranged from 60 μm to 1 mm and was measured by high definition camera. Oils of different density were used including castor, gasoline, diesel, and crude oil. Sound speed of each oil was measured using a Digibar Pro sound velocimeter.
Laboratory observations of the target strength of non-spherical gas bubbles in water
Authors: Weber Thomas C. , Pillsbury Liam , Loranger Scott
Published: May 2015

Naturally occurring methane bubbles in the ocean are often observed to have ellipsoidal or otherwise deformed shapes. Models of acoustic scattering from non-spherical gas bubbles suggest changes in resonance frequency and scattering strength relative to spherical gas bubbles with identical volumes. These changes potentially confound our ability to easily relate measurements of acoustic backscatter from gas bubbles to their size and quantity. To help quantify the magnitude of this effect, we have conducted a series of laboratory measurements of acoustic backscatter from non-spherical air bubbles rising from the bottom of a 6 m deep test tank. The acoustic measurements were made at frequencies between 10 kHz to 150 kHz, well above the frequency of bubble resonance (as is often the case for measurements of methane bubbles in shallow coastal environments). Laboratory measurements of bubbles with different sizes and deformations are compared with models for spherical bubbles with identical volumes.
Low frequency scattering from dynamic fish schools based on collective animal behavior modeling
Authors: Alfaro Simón E. , Cellio Jorge , Raveau Maria P. , Feuillade Christopher
Published: May 2015

Low frequency acoustic scattering from swim bladder fish is dominated by the monopole resonance response of the bladder. A school scattering model has previously been developed [Feuillade et al., J. Acoust. Soc. Am. 99(1), 196–208 (1996)] to predict levels of scattering from schools of bladder fish, which includes multiple scattering effects among the fish, and coherent summation of their radiated fields. In order to incorporate these acoustic interactions, the relative locations of the individual fish within the school are required as an input. To provide a realistic description of fluctuating levels of scattering from schools, a self-organizing model of group formation in three-dimensional space has been developed, based on biological principles of collective animal behavior [Couzin et al., J. Theor. Biol. 218, 1–11 (2002)]. In this model, organization within the school is a function of alignment, and repulsive and attractive tendencies based upon the position and orientation of the individual fish. The results of using this model to simulate the fish behavior demonstrate the spatial and temporal dynamics of the fish school, and indicate how these influence the statistical variability of the acoustic scattering response as a function of frequency. [Work supported by ONR.]
Bayesian environmental inversion of airgun modal dispersion using a single hydrophone in the Chukchi Sea
Authors: Warner Graham A. , Dosso Stan E. , Dettmer Jan , Hannay David E.
Published: May 2015

This paper presents estimated water-column and seabed parameters and uncertainties for a shallow-water site in the Chukchi Sea, Alaska, from trans-dimensional Bayesian inversion of the dispersion of water-column acoustic modes. Pulse waveforms were recorded at a single ocean-bottom hydrophone from a small, ship-towed airgun array during a seismic survey. A warping dispersion time-frequency analysis is used to extract relative mode arrival times as a function of frequency for source-receiver ranges of 3 and 4 km, which are inverted for the water sound-speed profile (SSP) and subbottom geoacoustic properties. The SSP is modeled using an unknown number of sound-speed/depth nodes. The subbottom is modeled using an unknown number of homogeneous layers with unknown thickness, sound speed, and density, overlying a halfspace. A reversible-jump Markov-chain Monte Carlo algorithm samples the model parameterization in terms of the number of water-column nodes and subbottom interfaces that can be resolved by the data. The estimated SSP agrees well with a measured profile, and seafloor sound speed is consistent with an independent headwave arrival-time analysis. Environmental properties are required for anthropogenic noise modeling studies in the Chukchi Sea and for improving acoustic localization of marine mammals detected with passive acoustic monitoring systems.
Measuring the acoustic scattering response of small groups of live fish in a laboratory tank
Authors: Raveau Maria P. , Feuillade Christopher , Venegas Gabriel , Wilson Preston S.
Published: May 2015

Assessing the validity of measurement/model comparison in fisheries acoustics is difficult, due to the uncertainty in ground truth for acoustic measurements obtained in the open water. One way to overcome this is to utilize laboratory measurements, where fish school parameters may be more well known. The primary purpose of this work was to investigate the feasibility of measuring the acoustic properties of a small group of live fish in a laboratory tank using a steady state subtraction method [J. Acoust. Soc. Am. 112, 1366–1376 (2002)]. Transfer function measurements were obtained in a fresh water tank that contained an enclosed group of goldfish (Carassius auratus auratus), in order to describe their resonance scattering behavior. The experimental results were compared with an existing predictive model [J. Acoust. Soc. Am. 99, 196–208 (1996)], which incorporates both multiple scattering effects between fish, and coherent interaction of their individual scattered fields. Computational modeling, experimental details and data/model comparison will be presented. This technique can be extended to larger tanks and other fish species. [Work supported by ONR.]
New parameters in shear wave elastography
Authors: Gennisson JeanLuc , Deffieux Thomas , Pernot Mathieu , Fink Mathias , Tanter Mickael
Published: May 2015

In the field of shear wave elastography, a specific technique called Supersonic Shear Imaging (SSI) was developed since almost 15 years. This technique is based on two concepts: By means of the acoustic radiation pressure phenomena shear waves are generated directly within tissues. Then, shear wave propagation is caught in real time by using an ultrafast ultrasound device (up to 20,000 frames/s). As shear wave speed is directly related to stiffness of tissues, such a concept allows to recover elastic maps of organs. Nevertheless, stiffness is not always only sufficient to better understand organs pathologies and behaviors. So, there is a need to add new parameters for a better characterization. In this context, SSI technique can be extended in order to reach new mechanical parameters, which can potentially help physicians. By looking at the shear wave dispersion, viscosity of tissues can be retrieved by using the right rheological model. Elastic anisotropy is recovered by rotating the probe at the surface of the investigated organ. For each position, the shear wave speed is calculated allowing to deduce orientation of fibers. At last, the change in tissue stiffness as a function of the pressure applied over medium, also called acoustoelasticity theory, allows the assessment of the nonlinear elastic properties. The combination of all these new parameters, viscosity, anisotropy, and nonlinearity, with stiffness offer new possibilities of diagnosis for physicians to better understand organs pathologies.
Using acoustic radiation force to probe tissue mechanical properties: Challenges and strategies
Authors: McAleavey Stephen A.
Published: May 2015

The acoustic radiation force phenomenon provides a highly flexible instrument with which to probe the mechanical properties of tissue. The ability to shape the applied force both in time and space, combined with the high sensitivity of ultrasound motion tracking, enables a multitude of techniques for the estimation of tissue mechanical properties. A present challenge is to reduce the measurement variance of these properties so as to better distinguish subtle variations associated with disease stage. Shear wave tracking is the starting point for many of these techniques, and can be used to characterize tissue in terms of group velocity, as well in terms of tissue constitutive model parameters. This talk will discuss sources of error in shear wave velocity and tissue parameter estimation and strategies for their avoidance or compensation. Time-domain estimation of viscoelastic parameters using a wave propagation model and maximum likelihood estimator will be described, along with challenges due to non-ideal source geometries.
Acoustic radiation force to reposition kidney stones in humans
Authors: Bailey Michael R. , Cunitz Bryan W. , Dunmire Barbrina L. , Harper Jonathan D. , Lee Franklin H. , Hsi Ryan , Sorensen Mathew D. , Lingeman James E. , Karzova Maria M. , Yuldashev Petr V. , Khokhlova Vera A. , Sapozhnikov Oleg A.
Published: May 2015

This is a report of the first clinical study to reposition kidney stones with acoustic radiation force. Studies were conducted with the approval of the University of Washington IRB and a U.S. FDA Investigational Device Exemption. Of the 15 subjects, average age was 56 ± 11 years; average BMI was 29 ± 3; and stone size range was dust to 13 mm. Two patients reported skin discomfort and sensation at depth with a few pushes. Otherwise, there was no pain or adverse effects associated with the treatment. Stones were repositioned in 14 subjects. Stones were repositioned to a new location in all 6 post-lithotripsy patients, while 4 of the 6 passed over 30 stone fragments within a few days of treatment. De novo stones and stones as large as 8 mm were repositioned. In four of the 15 subjects, what was noted in clinical imaging as a single, potentially unpassable stone was shown to be several passable stones upon repositioning with ultrasound. Ultrasonic propulsion can safely and without pain reposition kidney stones in humans. [Work supported by NIH NIDDK grants DK043881and DK092197 and National Space Biomedical Research Institute through NASA NCC 9-58.]
Simulation of ultrasound radiation force induced shear wave propagation in viscoelastic media using a mapped Chebyshev pseudospectral method
Authors: Qiang Bo , Brigham John C. , McGough Robert J. , Greenleaf James F. , Urban Matthew W.
Published: May 2015

We implemented a three-dimensional solver for simulating the ultrasound radiation force induced shear wave motion in viscoelastic media using a mapped Chebyshev pseudospectral method. The solver used a body force field that is simulated by the Field II program as the excitation. Then, a velocity-stress formulation was used to calculate the shear wave motion. We used a Voigt model to describe tissue viscoelasticity, and the viscosity is introduced by memory variables and auxiliary differential equations. The top boundary of the domain had a fixed boundary condition to mimic the interaction between an ultrasound probe and the tissue surface. All other sides of the domain were surrounded by perfectly matched layers to minimize the reflections. Time stepping was implemented with the LSODE integrator with variable step sizes. Results show that the waveform of the simulated shear wave is close to experimental observations and equivalent FEM simulations. We used a Fourier-based method to estimate the phase velocities of the shear waves between 100–1000 Hz and a nonlinear regression to estimate the Voigt model parameters. The reconstructions matched within 10% error compared with the true values.
Shear wave propagation and elasticity imaging of soft tissues under compression
Authors: Park Dae Woo , Nguyen Man M. , Kim Kang
Published: May 2015

In efforts to improve detection sensitivity of shear wave elasticity imaging of target tissue lesions with relatively small mechanical contrast to the background tissues, shear wave propagation characteristics in tissues under compression loading have been studied. A finite element hyperelastic tissue model was constructed to characterize the changes of propagating shear wave subject to different mechanical loading and to guide in vitro experiments. The shear wave speed sharply increased in an inclusion from 2.4 m/s to 6.3 m/s while it increased from 2.0 m/s to 4.0 m/s in the background tissue with overall compression loading from 0% to 30%. Increased shear wave reflection at the boundary of the inclusion due to increased mechanical contrast was lowered using a directional filter. In vitro experiments were performed using a soft phantom block (0.5% agar with 5% gelatin) that contains a hard inclusion (1.5% agar with 5% gelatin) of a long cylinder (D: 8 mm). The reconstructed shear modulus of the inclusion exhibited noticeable nonlinearity, in contrast to linear increase of shear modulus in the surrounding phantom. As a result, the elastic modulus contrast of the inclusion to the surrounding phantom was increased from 0.47 to 1.41 at compression from 0% to 30%.
Three-dimensional finite difference models of shear wave propagation in isotropic, homogeneous soft tissue
Authors: Yang Yiqun , Urban Matthew W. , McGough Robert J.
Published: May 2015

Shear wave elastography with ultrasound applies an acoustic radiation force to generate shear waves in viscoelastic soft tissue. To address the need for more effective simulation tools that model shear waves generated by an applied acoustic radiation force, three-dimensional (3D) finite difference programs that simulate propagation of shear waves in an isotropic, homogeneous medium have been created. These programs simulate shear wave propagation in elastic and viscoelastic soft tissue models. The 3D finite difference implementation combines an explicit time-stepping approach and a staggered spatial grid with an absorbing boundary condition that reduces boundary reflections. The acoustic radiation force in these simulations is quickly and accurately simulated in FOCUS (http://www.egr.msu.edu/~fultras-web) for a focused linear ultrasound array with an f/# of 2. The compressional wave speed is 1500 m/s and the shear wave speed is 1.5m/s in the elastic and viscoelastic tissue models, and the shear viscosity is 1 Pa·s in the viscoelastic model. The simulation completes 90,000 time steps of a 10 ms simulation in an 80 mm × 80 mm × 80 mm region with spatial sampling equal to the wavelength of compressional component in three days on a 3.4 MHz Intel i7 processor. [Supported in part by NIH Grants R01EB012079 and R01DK092255.]
Using social media tools efficiently and effectively for acoustics outreach and education
Authors: Morrison Andrew C.
Published: May 2015

The ability to quickly and easily reach a large public audience through social media outlets such as Twitter and Facebook makes these platforms ideal for raising awareness of acoustics-related studies and issues. Some researchers may be unable to dedicate a lot of time toward building and maintaining a social media presence. To make finding and disseminating information more efficient on social media sites, there are a series of tools, which can be combined together to automatically aggregate and post information online in ways which can save valuable time and effort. In this presentation, I will show my tool chains that are used to discover interesting acoustics-related news stories for sharing online and how they can be scheduled for posting over several days. I will also discuss surprising ways in which the automatic discovery of acoustics-related questions by non-scientists make for interesting tutorials to be used in acoustics classes at the undergraduate level.
The broader impact of practicing communication through social media: From Twitter to the National Science Foundation
Authors: Rudd Alexis B.
Published: May 2015

Available research funding has decreased in line with the Budget Control Act of 2011, which resulted in funding cuts across both defense and non-defense discretionary programs. These cuts have had a negative impact on many researchers, including those at the Acoustical Society of America. Legislation and appropriations by congress have a direct effect on the funding levels and research priorities of federal agencies. Clear and relatable communication of these impacts is important to both the public and the members of the US Congressional committees, most of whom do not have a background in scientific research. Consideration of the technical and educational background of the audience is vital to clear communication, and agencies such as the National Science Foundation (NSF) are placing increasing emphasis on the broader impacts of scientific proposals and how research will benefit the people of the United States. Social media is an opportunity for scientists to get real-time feedback on science communication and to practice translating scientific jargon for an audience of non-specialists and explaining technical concepts succinctly (often in 140 characters or less).
Health and well-being related to wind turbine noise exposure: Summary of results
Authors: Michaud David
Published: May 2015

This paper summarizes the results of the Health Canada Wind Turbine Noise and Health Study. One participant between the ages of 18–79 years was randomly selected from each household. The final sample included 1238 participates (606 males) living between 0.25 and 11.22 km from wind turbines. The response rate was 78.9% and did not significantly vary across sampling strata or between provinces. Wind turbine noise (WTN) exposure was not found to be related to hair cortisol concentrations, resting blood pressure, resting heart rate, or any of the measured sleep parameters. Self-reported results obtained through an in-person questionnaire do not provide support for an association between increasing WTN levels and self-reported sleep disturbance, use of sleep medication, or diagnosed sleep disorders. Similarly, no significant association was found between WTN levels and self-reported migraines, tinnitus, dizziness, diabetes, asthma, hypertension, perceived stress, or any measure of quality of life. Statistically significant exposure-response relationships were observed between increasing WTN levels and an increase in the prevalence of long term high annoyance towards several wind turbine features, including: noise, shadow-flicker, visual impacts, and vibrations. The influence of background noise on annoyance and the association between WTN annoyance and other reported and measured outcomes is presented.
Indoor and outdoor narrowband measurements of low frequency and infrasonic noise from wind turbines
Authors: Beaudry Allan , Bahtiarian Michael
Published: May 2015

The acoustic impact from industrial-grade wind turbines was studied for turbines located in Cape Cod, Massachusetts. Narrowband and one-third-octave band infrasonic and low frequency measurements were performed at a residence located in proximity to the Vestas V82-1.65 MW wind turbines. Surveys were undertaken inside and outside the residence on multiple occasions under various wind speeds and wind directions. In each case, measurements were performed using an infrasonic microphone prior to, during, and following the nightly shutdown period of the turbines. The spectral results show the existence of discernible tones occurring at the blade passage frequency and its harmonics during operation and absent with the turbines secured. Additional tones where found in the very low audible frequency range with sidebands separated by the blade passage frequency. Comparisons have been made of the indoor and outdoor measurements as well as the effect of wind speed and direction on tone amplitude and prominence. The use of overall G-weighted noise levels to characterize these low frequency tones is also examined.
Changes in ambient sound levels observed in relation to the operational status of the Mesa Wind Project Site
Authors: Briggs Jessica , McKenna Dr. Megan F. , Fristrup Kurt M.
Published: May 2015

Type 1 sound level measurements and continuous audio recordings were obtained from two sites near the Mesa Wind Project Site (MWPS), 100 m and 1500 m from the nearest turbine. The sites were upwind of the turbines. Unexpectedly, MWPS ceased operating 29 days after this project began; data were collected for an additional 127 days. Contrasts in hourly summaries of 1 second 1/3rd octave sound level measurements, controlled for hourly mean wind speed, revealed the contributions of rotating blades. For the near site, at wind speeds below 5 m/s, 1/3rd octave band levels increased starting at about 100 Hz, with distinct spectral peaks appearing between 400 Hz and 2000 Hz. These spectral peaks were less prominent when hourly mean wind speed was 5 m/s or greater. At the far site, small increases in sound level were observed for 1/3rd octave bands at 1 kHz and below when the blades were turning. The levels measured in this study will be compared with levels measured at NPS sites, to evaluate distances at which operational wind farms might affect park acoustical environments.
“Waking in an anxious frightened panicked state” and “pressure bolt sensations”—what clinical and acoustic clues can tell us about the causes of deteriorating physical and mental health
Authors: Laurie Sarah E.
Published: May 2015

Residents living in quiet rural areas report a variety of new symptoms correlating with exposure to new acoustic emissions from industrial sound and vibration sources, including large wind turbines, of which sleep disturbance is the most common. Some residents and their health practitioners report a unique pattern of sleep disturbance, which indicates physiological stress is occurring concurrently. Other clinical and acoustic clues such as “pressure bolt” sensations correlating with independently measured pressure pulses will also be shared. Neurophysiological pathways which appear to be activated by these acoustic stimuli will be discussed, followed by reference to the extensive body of clinical research supporting the current knowledge that both chronic sleep deprivation and chronic stress directly exacerbate pre existing diseases, as well as directly cause new diseases resulting in serious and sometimes irreversible damage to physical and mental health. Finally, specific research to investigate these physiological and pathological impacts, in order to determine safe threshold exposure levels for long term exposure to impulsive infrasound and low frequency noise will be proposed.
Annoyance of wind-turbine noise as a function of amplitude-modulation parameters
Authors: Ioannidou Christina , Santurette Sébastien , Jeong Cheol-Ho
Published: May 2015

Amplitude modulation (AM) has been suggested as an important factor for the perceived annoyance of wind-turbine noise (WTN). Two AM types, typically referred to as “normal AM” and “other AM,” depending on the AM extent and frequency region, have been proposed to characterize WTN AM. The extent to which AM depth, frequency, and type affect WTN annoyance is a matter of debate. In most subjective studies, the temporal variations of WTN AM have not been considered. Here, a sinusoidally modulated WTN model accounting for temporal AM variations was used to generate realistic artificial stimuli in which the AM depth, frequency, and type, while determined from real on-site recordings, could be varied systematically. Subjective listening tests with such stimuli showed that a reduction in AM depth, quantified by the modulation depth spectrum, led to a significant decrease in annoyance. When the spectrotemporal characteristics of the original far-field stimuli were included in the model and the temporal AM variations were taken into account by varying the modulation index over time, neither AM frequency nor AM type were found to significantly affect annoyance. These findings suggest that the effect of AM parameters on WTN annoyance may depend on the intermittent nature of WTN AM.
Acoustic multipole source inversions of volcano infrasound
Authors: Kim Keehoon , Fee David , Lees Jonathan M. , Yokoo Akihiko , Ruiz Mario C.
Published: May 2015

Sources of volcano infrasound involve the atmospheric displacement associated with volcanic eruptions, where characteristic source dimensions are generally confined by the vent. Volcano infrasound sources are typically considered as a monopole which corresponds to the first-order term in the acoustic multipole expansion. However, when the wavelength becomes comparable to the size of the vent, the source may have further complexity which can be described only by higher-order terms, yet such complexity of volcano infrasound source has not been extensively explored. This is mainly due to (1) limited sampling of the acoustic wavefields due to poor network coverage and (2) complex sound propagation near the volcanic edifice which significantly distorts the multipole acoustic wavefields. In this study, we present a linearized waveform inversion technique incorporating numerical Green's functions. A full 3-D Finite-Difference Time-Domain (FDTD) method accelerated with GPU is used to compute accurate Green's functions taking into account volcano topography. The presented method is applied to infrasound data recorded at Sakurajima volcano (Japan) and Tungurahua volcano (Ecuador) and volcano infrasound sources associated with explosive eruptions are characterized in terms of a monopole and dipole. These methods could be applied to chemical explosions as well to determine source characteristics and complexity.
Infrasound from underwater sources
Authors: Evers Läslo , Brown David , Heaney Kevin , Assink Jelle , Smets Pieter , Snellen Mirjam
Published: May 2015

Atmospheric low-frequency sound, i.e., infrasound, from underwater events has not been considered thus far, due to the high impedance contrast of the water-air interface making it almost fully reflective. Here, we report for the first time on atmospheric infrasound from a large underwater earthquake (Mw 8.1) near the Macquarie Ridge, which was recorded at 1325 km from the epicenter. Seismic waves coupled to hydroacoustic waves at the ocean floor, after which the energy entered the Sound Fixing and Ranging channel and was detected on a hydrophone array. The energy was diffracted by a seamount and an oceanic ridge, which acted as a secondary source, into the water column followed by coupling into the atmosphere. The latter results from evanescent wave coupling and the attendant anomalous transparency of the sea surface for very low frequency acoustic waves.
Probabilistic infrasound propagation using ensemble based atmospheric perturbations
Authors: Smets Pieter , Evers Läslo
Published: May 2015

The state of the atmosphere is of utmost importance for infrasound propagation. In propagation modeling, the true state of the atmosphere is mainly represented by the analysis. The analysis is the best deterministic estimate of the atmosphere using a data assimilation system existing of a General Circulation Model (GCM). However, the analysis excludes error variances of both model and observations. In addition, the coarse resolution of GCM results in averaging of, e.g., clouds or gravity waves, over larger regions known as parameterization. Consequentially, arrivals due to fine-scale structure in wind and temperature can be missing. Therefore, infrasound propagation including the atmospheric best-estimate error variances based on an ensemble model is proposed. The ensemble system exists of model perturbations with an amplitude comparable to the analysis error estimates to obtain a probability density function. The best-estimate analysis error variances are described by a set of perturbations using the European Centre for Medium-range Weather Forecasts (ECMWF) Ensemble Data Assimilation (EDA) system. Probabilistic infrasound propagation is demonstrated by one year of mining activity, e.g., blasting, in Gällivare, northern Sweden, observed at infrasound array IS37 in Norway, part of the International Monitoring System (IMS) for verification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). Probabilistic infrasound propagation is compared with the standard deterministic result obtained using the analysis.
Understanding cross-modal interactions of spatial and temporal information from a cortical perspective
Authors: Shinn-Cunningham Barbara , Michalka Samantha , Noyce Abigail , Somers David
Published: May 2015

In the ventriloquism effect, perception of visual spatial information biases judgments of auditory events, yet there is little effect of auditory stimuli on perception of visual locations. In the flash-beep illusion, the number of auditory “beeps” biases judgments of the count of visual flashes, but visual flashes have little effect on perceived number of auditory events. These asymmetries suggest that vision is the “natural” sensory modality for coding spatial information, while audition is specialized for representing temporal information. Here, we review recent behavioral and neuroimaging evidence from our labs exploring the neural underpinnings of such perceptual asymmetries. Specifically, we find that there are distinct frontal cortical networks associated with visual information and auditory information. Yet these networks can be recruited by the other sensory modality, depending on task demands. For instance, when judging spatial aspects of auditory inputs, neural areas associated with visual processing are recruited; when judging temporal aspects of visual inputs, areas associated with auditory processing are activated. We also find another asymmetry: knowing when a spatial event is going to occur helps listeners judge location, but knowing where an event will occur does not help judgments about that event's timing. These kinds of studies help elucidate how temporal and spatial information is encoded in the brain, and the neural mechanisms by which visual-spatial and auditory-temporal information interact.
Non-phonemic benefits of visual cues in the perception of consonants
Authors: Brungart Douglas , Bielski Lynn M. , Thompson Eric R.
Published: May 2015

Visual cues from the talker’s face improve speech perception because the talker adopts discrete facial configurations, known as visemes, corresponding to a limited number of possible phonemes in the auditory signal. Visual cues alone are insufficient for complete recovery of the speech signal, because individual visemes can occur with more than one phoneme. Visual speech cues may provide non-phonemic benefits in noise through segregation of target speech from background sounds. This experiment isolated phonemic and non-phonemic benefits of visual cues through identification of strings of consonants (i.e., aCHaBaGa) in an eight-alternative forced choice task. Listeners discriminated each consonant presented from a randomly selected foil in each position. In the heterovisemic case, the foil had a different viseme than the target. In the homovisemic case, each foil was from a list of consonants with the same viseme as the target, meaning the visual target provided no phonetic information about the speech. Results show benefit from visual speech cues in the homovisemic condition roughly half the size of that in the heterovisemic condition. This suggests a substantial portion of the visual benefit can be attributed to factors other than extraction of phonemic information from visemes in the visual stimulus.
Defying the physical: Acoustic design as a medium for reimagining space and recontextualizing expression
Authors: Gibbs Bobby E. , Braasch Jonas
Published: May 2015

Just as the physical laws of light are both an inspiration and a point of departure for visual artists, the canvas of acoustic design is not aesthetically bound to real spaces. Using findings from venue visits, interviews and an interactive virtual auditory exploration, we will discuss the bricolage of physical space and cultural expression inherent in the dissemination of a unique musical genre. In particular, we will explore how experimental improvisers preserve and subvert spatial cues to create aural experiences that are at once intimate and illusive.
Dynamic binaural sound source localization with ITD cues: Human listeners
Authors: Zhong Xuan , Yost William , Sun Liang
Published: May 2015

In real life, human listeners rarely experience cone of confusion errors in localization of sound sources due to the limitation of interaural time difference (ITD) as a spatial hearing cue. Previous work on robotics suggested that the confusion is disambiguated as successive observation of ITD is made over time, when self-motion of the microphone system was allowed. In this behavioral study, we investigated whether horizontal/vertical planes localization with time difference is possible when self-motion is allowed for human listeners. In particular, the case of a static sound source playing low frequency pure tone signal was studied. Human listeners were seated in a rotating chair in the middle of a loudspeaker array, and a low frequency audio signal was played at an elevation. The task was to identify the elevation spatial angle under conditions when vision was allowed and denied. The hypothesis was, with vision, a much more robust observation of self-motion is available, and the report of elevation would be more accurate. The results largely agreed with the hypothesis. A similar study for robotic hearing generated similar results.