bluuebunny/crossref_metadata_2025 huggingface dataset:
Exploration of acoustical and dynamical properties of organic nanoparticle assemblies for increased sound insulation
Authors: Whitney Mathew A. , Xiang Ning , Malakooti Sadeq , Churu Habel G. , Leventis Nicholas , Lu Hongbin
Published: April 2018

Low-density highly porous solid monolithic macroscopic objects, consisting of hierarchical mesoporous three-dimensional assemblies of nanoparticles (aerogels), have been previously pursued mainly for their low thermal conductivity. Unlike classical aerogels based on silica being fragile materials, structural fragility issue has been addressed with materials referred to as polymer-crosslinked (or X-) aerogels. X-aerogels are low-density materials, yet their mechanical strengths have been significantly increased. This work explores ductile aerogels in potential uses as constrained damping layers integrated into classical wallboards for drastically increased sound transmission losses without significantly increasing the board thickness and weight. Their ductility and mechanical strength enables light-weight X-aerogel panels of less than 1 cm in thickness to be integrated into gypsum wallboards. This work has experimentally investigated the integrated wallboards to achieve significantly increased sound transmission loss without significantly increasing thickness and weight of integrated wallboard system. This paper discusses preliminary investigations on experimental methods to characterize broadband dynamic properties of X-aerogels for better understanding of its excellent effect in drastically increased sound transmission loss. Some preliminary test results carried out in chamber-based random-incident measurements demonstrate high potentials in building acoustics applications and beyond.
Large scale metasurfaces for seismic waves control
Authors: Palermo Antonio , Krödel Sebastian , Matlack Kathryn , Zaccherini Rachele , Dertimanis Vasilis , Chatzi Eleni , Marzani Alessandro , Daraio Chiara
Published: April 2018

Elastic metamaterials are artificial composites with subwavelength resonant particles hosted in a medium able to manipulate the propagation of elastic waves. When the resonant particles are placed at the free surface of the medium to form a resonant “metasurface,” the localization mechanism and the direction of surface waves can be fully controlled. In this talk, we discuss the use of resonant metasurfaces to control the propagation of vertically and horizontally polarized surface waves and their possible application for seismic waves mitigation. By combining analytical, numerical, and experimental studies, we describe the interaction of Rayleigh waves with a metasurface of vertical resonators and design large-scale resonant barriers to deviate damaging seismic Rayleigh waves into the medium bulk. Additionally, we investigate the effect of material stratification on the metasurface dynamics by analyzing the propagation of surface waves in unconsolidated granular media with depth-dependent stiffness profile. Finally, we describe the interaction of Love waves guided by a stratified medium with a metasurface of horizontal resonators and design large-scale resonant metalenses to redirect their propagation.
Groundborne vibration attenuation by particulate dampers to reduce building vibration at sonic frequencies
Authors: Tavossi Hasson M.
Published: April 2018

Particulate medium can act as efficient damper for building vibrations. Mechanical properties of particulate material and their size distributions determine their vibration absorption characteristics. Unconsolidated particulate damper of uniform size is shown to have bandpass filter behavior for mechanical vibrations that are transmitted through them. The dampers absorption spectrum also shows bandgap structure where mechanical vibration in each frequency range is strongly absorbed. We use samples of uniform size spherical particulates that are subjected to mechanical vibrations in the audible frequency range to determine their absorption characteristics as a function of particle size, frequency, intensity, and direction of propagation. The effects of particle sizes and layer thickness on vibration absorption are determined. The goal is to determine the required absorption characteristics as a function of particle size distribution, that is required to mitigate building vibrations.
Deep reinforcement learning for cognitive sonar
Authors: Summers Jason E. , Trader Jason M. , Gaumond Charles F. , Chen Johnny L.
Published: April 2018

Current developments in cognitive sonar have leveraged explicit semantic representations such as ontologies to develop cognitive agents that enable adaptation of sonar settings to optimize behaviors such as waveform selection during active tracking. However, such cognitive systems based on explicit knowledge representations can be time-and-labor intensive to update in operation and limited in ultimate performance. In other applications, such as computer Go, breakthrough performance was achieved by going beyond learning from all prior games and actions of experts to allowing the algorithm to compete with itself to develop and learn from the outcome of new approaches. This hybrid approach of learning from experts and then learning via self-competition is vital for sonar applications such as active antisubmarine warfare (ASW) because ground-truthed performance data are sparse and may not display optimal solutions. Here, we discuss our application of reinforcement learning to active ASW in a simulated environment based on computational-acoustics models, including an assessment of the goal states and performance metrics we have used. The fidelity of the simulated environment is discussed in terms of the interaction with reinforcement learning and the impact on generalization from learning in simulated environments to application in real environments. [Work supported by ARiA IR&D.]
Coupled FE/BE for periodic acoustic systems
Authors: Wixom Andrew S. , Hanford Amanda , Pitt Jonathan S. , Wolfe Douglas E.
Published: April 2018

While coupled finite element and boundary element (FE/BE) codes are used regularly in acoustics—particularly structural acoustics—and periodic boundary conditions are common, the combination of the three is rare. However, such calculations have been performed in the electricity and magnetism community for quite some time. This talk presents a fully coupled FE/BE framework for acoustics with doubly-periodic boundary conditions, accomplished by way of the Ewald transformation of the appropriate periodic Green’s function. This method is likely of primary interest to the acoustic metamaterials community and it is used to analyze an example problem drawn from this field. Both the internal acoustic field within the FE mesh as well as the system’s radiation characteristics are examined.
Radiation force on spheres in standing waves in ideal fluids: Improved simple approximation for material dependence
Authors: Marston Philip L.
Published: April 2018

When spheres are much smaller than the acoustic wavelength but sufficiently large that viscous dissipative properties are insignificant, the Yosioka-Kawasima approximation for the radiation force in standing waves is widely used. One consequence is that the force is taken to be proportional to the sphere’s volume. One approach to finding how corrections to that approximation depend on material properties is to start with Hasegawa’s full partial-wave-based series and convert it to partial-wave phase shifts using analytical relations [L. Zhang and P. L. Marston, J. Acoust. Soc. Am. 140, EL178–EL183 (2016)]. When all the relevant phase shifts are real and sufficiently small in magnitude, a simple approximation can be found for (possibly imaginary) frequencies giving vanishing forces. That was an unanticipated application. (Material dissipation and surface tension are taken to be insignificant.) Using that frequency root, a modification of the Yosioka-Kawasima radiation force is derived that allows for the liquid or solid sphere to be finite in size [P. L. Marston, J. Acoust. Soc. Am. 142, 1167–1170 (2017) and at press]. The force is no longer strictly proportional to the volume. This approach is supported by numerical comparisons with Hasegawa’s series when the phase shifts are small. [Research supported by ONR.]
Difficulty with understanding speech in background noise is predicted by broad binaural pitch fusion in bimodal cochlear implant users
Authors: Oh Yonghee , Srinivasan Nirmal Kumar , Diedesch Anna C. , Hartling Curtis , Gallun Frederick J. , Reiss Lina
Published: April 2018

Combined use of a cochlear implant (CI) and a contralateral hearing aid has been shown to improve CI users’ speech perception performance in multi-talker environments, presumably due to the use of acoustic temporal fine structure cues for separating one talker from several other talkers. However, there is large variability in this bimodal benefit. In this study, we show that differences in width of binaural pitch fusion, the fusion of dichotically presented tones that evoke different pitches across ears, explain a large part of this variability. Specifically, broad binaural pitch fusion could lead to fusion of multiple voices as one voice, and reduce the ability to use voice pitch differences to separate voices and understand speech in a multi-talker environment. Speech reception thresholds measured using male and female target talkers were compared with binaural pitch fusion results. Overall performance improved with different genders for target and maskers. A strong negative correlation was observed between voice gender benefit and breadth of binaural pitch fusion. These results suggest that sharp binaural pitch fusion is necessary for maximal speech perception in noise when acoustic hearing is available to transmit voice pitch cues. [Work supported by NIH-NIDCD Grant Nos. R01 DC01337 and F32 DC016193.]
Early temporary asymmetrical hearing impairs behavioral and neural sensitivity to sound location
Authors: Anbuhl Kelsey L. , Tollin Daniel J.
Published: April 2018

Children experiencing asymmetrical hearing early in life often display binaural hearing impairments that persist long after symmetric hearing is restored, suggesting abnormal central auditory development. Here, we test the hypothesis that abnormal neural coding of the interaural level difference (ILD) cue to sound location, resulting from asymmetrical hearing during development, underlies the hearing impairments. Guinea pigs were reared for 8 weeks from birth with a unilateral conductive hearing loss (CHL via earplug). After earplug removal we measured behavioral spatial acuity, the binaural interaction component (BIC) of the auditory brainstem response (ABR), and sensitivity to ILDs in auditory midbrain neurons (inferior colliculus, IC). Animals raised with asymmetric hearing displayed worse spatial acuity (~2x worse) for high-pass noise compared to age-matched controls, suggesting impaired sensitivity to ILDs. Physiologically, animals displayed abnormal BICs of the ABR indicating altered binaural processing in the auditory brainstem. Additionally, ILD discrimination thresholds for single neurons in the IC, determined using Fisher Information, were ~2 times worse than that found in controls. These results suggest that experiencing even temporary asymmetric hearing during early development persistently alters the normal development of spatial hearing, which may be attributed to impaired binaural processing at the level of the brainstem and midbrain.
Interhemispheric auditory cortical relationships in asymmetric hearing loss
Authors: Cheung Steven W.
Published: April 2018

Directional acoustic trauma, sudden hearing loss with incomplete recovery, Meniere’s disease, and cerebellopontine angle tumors are common clinical conditions that present with asymmetric hearing loss (ASL). Presentation of input signals from both ears for interhemispheric processing may be necessary to achieve the best hearing outcomes. To review temporal and spatial interhemispheric functional relationships revealed by microelectrode mapping studies in an animal model of ASL and by functional imaging studies in human single-sided deafness (SSD). Animal and human cohort comparison studies by investigators at the University of California. In animals with mild-to-moderate ASL, interaural temporal difference is a strong driver of cortical plastic change. Six months after hearing loss induction, the two cortices reorganize into a state of relative local hemispheric autonomy. In humans with SSD, temporal and spatial cortical plastic change is evidenced by reduced interhemispheric mean difference of the M100 peak response latency and increased activation spread distance in the hemisphere contralateral to the only hearing ear and decreased distance in the ipsilateral hemisphere in SSD subjects to tonal stimuli, respectively. Variations in hearing outcomes for acoustical and electrical rehabilitation of the poorer ear in ASL may be related particular states of interhemispheric relationships.
Directional pointing error in “Spatial Matched Filter” beamforming at a tri-axial velocity-sensor with non-orthogonal axes
Authors: Nnonyelu Chibuzo J. , Lee Charles H. , Wong Kainam T.
Published: April 2018

The “tri-axial velocity-sensor” has three axes that are nominally perpendicular, but may be non-perpendicular in practice, due to real-world imperfections in manufacturing, deployment, or maintenance. This paper investigates how such non-perpendicularity would affect the tri-axial velocity-sensor’s azimuth-elevation beam-pattern in terms of the beam’s pointing direction.
Sparse array performance in channels of limited coherence
Authors: Pyzdek Andrew T. , Swanson David C.
Published: April 2018

Sparse arrays reduce the number of redundant measurements for lags on an array in comparison to fully populated arrays. For ideal measurements, where spatial stationarity is maintained and measurement error is minimal, the performance of such arrays can be shown to be similar to that of a uniform array of the same length with appropriate processing techniques. However, for complex environments with limited spatial coherence or noisy measurements, array sparsity can impact performance. We construct a simple model that relates the relative positions of redundant measurements and channel coherence length to the variance of covariance function estimates, determine a set of lag measurement weightings that minimize said variance for a given set of redundant lag positions, determine a set of conditions on which a uniform weighting is optimal, and demonstrate that regularly spaced lag repetitions optimally sample a spatially varying covariance function.
Portable goniometers with high angular resolutions and large radii for experimental investigations of acoustic diffractions
Authors: Kawasaki Jonathan , Xiang Ning , Stoffle Jolene , D'Antonio Peter
Published: April 2018

Surface scattering and diffuse reflections of acoustic diffusers are of relevance in room-acoustics simulations or for characterization purposes. Polar responses of diffraction objects to acoustic plane-wave excitations can be experimentally characterized using a circular microphone array: acoustical goniometer. Recently, the Graduate Program in Architectural Acoustics at Rensselaer Polytechnic Institute has begun to explore the advanced physical theory of diffraction (PTD) [Xiang and Rozynova, J. Acoust. Soc. Am., 141, pp. 3785 (2017)]. In order to validate the PTD applied to a number of canonical shapes (rigid wedges or plates) of finite sizes, experimental investigations on the diffraction objects need to be carried out with high angular resolutions and sufficiently wide angular ranges. A large radius of the acoustical goniometer is also crucial to satisfy acoustical far-field conditions. This talk will discuss the effort in implementation and processing algorithms for various radii of portable acoustical goniometers between 1 m and 4 m with angular resolutions up to 1.25 degrees, that can be easily deployed in indoor empty spaces of sufficient dimensions for an angular range across 180 degrees and beyond when diffusers or diffraction objects with one-axis symmetry need to be experimentally characterized.
High spatial resolution scanning for experimental room-acoustic measurements in scale models
Authors: Tay Daniel , Xiang Ning , Alamuru Aditya
Published: April 2018

This paper presents an experimental study of low frequency behavior of sound propagation in acoustically coupled volumes. The experiments are carried out in an eighth-scale model of two coupled volumes with an automated high spatial-resolution scanning system. Both sound pressure and three-dimensional sound intensities are automatically measured in terms of room impulse responses at each scanning positions over densely defined two-dimensional grids covering the entire areas of the two coupled rooms that enable the analysis and visualization of sound energy and sound energy flows. Through these measurements, and with the aid of a predictive computational model, this paper will discuss low frequency modal behaviors of sound energy flows within one of two coupled volumes. As such, the distribution of potential and kinetic energies, as well as that of active and reactive sound intensities within the coupled space will be separately analyzed. The distributions of intensity vector fields are compared through computational simulation. Consequently, a discussion on possible discrepancies in modal distributions between the computational and experimental results rounds off this paper.
The irrelevant speech effect in multi-talker environments: Applications to open-plan offices
Authors: Yadav Manuj , Cabrera Densil , Brooker Lucas , Love James , Kim Jungsoo , de Dear Richard
Published: April 2018

Irrelevant speech from co-workers has consistently been listed as one of the major nuisances within open-plan work environments. To explore the psychoacoustic basis of the so-called irrelevant speech effect (ISE; which causes cognitive decline and increases acoustic distraction) within a multi-talker context, a series of laboratory-based experiments were run. These experiments used room acoustical simulations of various open-plan office environments within a climate-controlled chamber to test several factors relevant to the ISE. These factors included the number of simultaneously active talkers, their spatial arrangements, sound pressure levels and the semanticity of speech. The main findings thus far indicate that multi-talker speech lead to a stronger ISE than speech from a single talker, which further interacts with the overall sound level, semanticity, etc., to exhibit a more complicated effect than what has been proposed in previous studies. The effect of the number of active talkers alone suggests reconsiderations of some assumptions in the ISO 3382-3. More generally, the perception of speech “babble” seems to be affected by multiple factors in a realistic working environment. Some of our research is directly related to characterising speech babble and its function as a beneficial sound masker in multi-talker environments.
Experiments with high-back chairs and retroreflective surfaces for increasing the support of one’s own voice over short conversational distances
Authors: Cabrera Densil , Yadav Manuj , Reinhardt Dagmar , Holmes Jonothan , Ciccarello Beau , Caldwell Hugo , Hannouch Adam
Published: April 2018

Acoustic support of one’s own voice affects speech, and increased support can foster more relaxed voice projection, which reverses the Lombard effect. While hearing one’s own voice in typical rooms shows subtle influences of “global” room acoustics, local treatment can yield stronger effects for talking-listeners. This paper considers two types of architectural acoustic treatment for supporting one’s own voice and modifying speech propagation—high-back chairs and retroreflective ceilings. For a talking-listener, local acoustic treatment such as high-back chairs can be designed to selectively attenuate ambient noise while providing enhanced reception of sound from a particular direction, project speech towards a listener with increased gain for speech intelligibility, and also provide voice support. Acoustically retroreflective surfaces (e.g., ceilings and vertical partitions) provide increased voice support by reflecting a person’s voice back to them, without such local treatment. This also has the advantage of reducing the transmission of speech beyond the conversation, providing a way to ameliorate speech distraction in multi-talker environments. This paper describes experiments in which the voice support of such treatments is quantified, via oral-binaural transfer functions. Results are supported with numerical simulation (finite-difference time-domain), and discussed in relation to practical design solutions for speech privacy and vocal comfort.
Impact noise of bare concrete slabs
Authors: Dong David W. , LoVerde John , Morin Michel
Published: April 2018

A poured concrete slab with no finish flooring and no ceiling is one of the simplest floor assemblies possible. Most structural slabs share similar design parameters such as density, mix, and compressive strength, and might be expected to have a similarly limited range of impact noise isolation. The authors have compiled a large number of bare slab tapping tests performed in laboratories, which provides information on the uncertainty in the test method for the specific assemblies used in the laboratory tests. The authors have compiled a large number of field impact tests on bare slabs in buildings, and the data reveals a surprisingly large variation in the impact sound pressure levels for actual slabs. The effects of this variation is discussed, including the suitability of various ratings of impact sound insulation, the relationship between laboratory and field measurements, and the uncertainty of impact noise measurements.
Finite element modeling of Rayleigh wave propagation in a laboratory sand tank
Authors: Ragusa Anthony F. , Miller James H. , Potty Gopu R.
Published: April 2018

Rayleigh waves were measured in a laboratory sand tank using an array of accelerometers. This tank allows for the measurement of interface waves for various sediment and soil arrangements in a well-controlled laboratory setting. Rayleigh waves were excited by simple impulsive sources including dropped balls and hammer impacts. In this study, a finite element modeling tool developed by Sandia National Laboratories was used to simulate the sand tank during these excitations. Different modeling scenarios were investigated. Time series of the Rayleigh wave arrivals were modeled at the sensor locations using time domain analysis. A calibrated bender element system was also developed to provide direct measurements of the shear wave speed profile at selected depths. These data were used to develop the material property input parameters for the finite element analysis. The simulated time series at the sensor locations are compared to the accelerometer data. [Work supported by Army Research Laboratory and BOEM.]
Beamwidth in bat biosonar and man-made sonar
Authors: Müller Rolf , Todd Bryan D.
Published: April 2018

Beamwidth measures how a sonar system distributes emitted energy or receiver sensitivity over angle. For man-made sonars, this is considered to be of critical importance, since a small beamwidth supports high-resolution imaging. For bat biosonar, the role of beamwidth is far less clear. In order to investigate how biosonar beamwidths could compare to its man-made peers, we have compiled beamwidth data for bats (based on numerical predictions) and man-made sonar systems (based on data sheets). An analysis of this data shows that bat biosonar and man-made sonars operate in very different regimes with respect to the ratio of characteristic dimension (i.e., aperture diameter for bats and array length for man-made sonars) to wavelength. Whereas the aperture diameters of bats ranged from falling below the employed wavelength to being about 10 times larger, man-made sonars were typically at least one order of magnitude larger than the employed wavelengths and ranged up to 1000 times larger. Furthermore, for any given characteristic-dimension-to-wavelength ratio, bats showed much more variability in beamwidth than man-made sonar. In fact, the variability in the bat beamwidths was found to be as large as that in a set of random horns, which indicates a role for other determining factors.
3D underwater sound propagation in coastal environments
Authors: Lin Ying-Tsong , Reeder D. Benjamin , Ralston David K.
Published: April 2018

Underwater sound propagation in a coastal ocean can be influenced by a variety of physical oceanographic conditions that are unique in the coastal and estuarine environment, such as salt wedge fronts, river-plume induced nonlinear internal gravity waves, strong tidal currents, surf zone waves, etc. The confined boundaries in the area can also produce reflection, diffraction and even scattering of sound due to shoaling seafloor. The morphological dynamics in the area is complex and results in corrugated and channeled bathymetry, which may cause 3D ducting and trapping of sound. In this talk, we will present our numerical study of 3D underwater sound propagation in Long Island Sound, a tidal estuary of the Atlantic Ocean. The Unstructured Grid Finite Volume Community Ocean Model (FVCOM) will be utilized to simulate physical oceanographic processes and produce water-column environmental input to the sound propagation model. A bathymetric database from high-resolution multibeam surveys will also be used to incorporate the realistic seafloor depth in the model. The numerical model results will be analyzed to present the evidences of 3D sound propagation effects and investigate the causes.
Spectral quantification of a tidal plume from an autonomous underwater vehicle
Authors: Lavery Andone C. , Jurisa Joseph T. , Geyer W. Rockwell
Published: April 2018

Buoyant plumes are ubiquitous in estuarine environments, yet their frontal structure and dynamics are not fully understood. Tidal plumes are dynamic over a broad range of temporal and spatial scales, and are characterized by strongly stratified turbulence and frontal instabilities. Observations from autonomous underwater vehicles (AUVs) with a suite of sensors, including temperature, salinity, and acoustic backscatter, provide a useful complement to ship-board sampling to characterize the frontal structure and dynamics at high resolution. Results are presented from an experiment in which a broadband acoustic backscattering system (160–410 kHz) was integrated onto a REMUS-100 AUV and used to sample the near-field ebb tide plume at the mouth of the Connecticut River. Scattering mechanisms are determined from the frequency-dependent acoustic spectra, and acoustic measurements of the frontal structure are compared to data collected with a towed CTD array. Data are also presented that illustrate the challenges associated with AUV operations in estuarine environments, including high currents, shallow and variable bathymetry, large buoyancy changes, and bubble entrainment at the plume front.
Progress in the utilization of focused ultrasound for treatment of the brain
Authors: Hynynen Kullervo
Published: April 2018

Magnetic Resonance imaging (MRI) guided focused ultrasound (FUS) has been shown to be able to safely ablate deep tissues in the brain in clinical settings resulting in reduction in recovery time and complications. Pre-clinical work has demonstrated that FUS energy when combined with micro bubbles(MB) could be used also for image-guided drug delivery into tumours and brain. The preclinical studies have shown significant survival benefits when FUS + MBs has been used to open the blood-brain-barrier (BBB) for large molecular chemotherapy agents, antibodies, and natural killer cells. Effective and safe delivery of nanoparticles and viral vectors has also been shown. This talk will briefly review the physical and engineering aspects related to the clinical FUS + MB exposures. The first ongoing clinical trials investigating the feasibility and safety of FUS + MB enhanced BBB permeability will be reviewed. Finally, the next generation phased array technology and the ultimate clinical potential of the FUS + MBs in brain treatments will be discussed.
Wideband transskull refocusing of ultrasound beams using dual-mode ultrasound arrays: Ex vivo results
Authors: Aldiabat Hasan , O'Brien Parker D. , Liu Dalong , Ebbini Emad S.
Published: April 2018

Transcranial focused ultrasound (tFUS) is capable of providing subtherapeutic and therapeutic ablative treatments for a variety of brain disorders. A major challenge towards widespread use of tFUS-based therapies stems from the complexity of the skull that could result in severe loss of focusing gain. Using extensive hydrophone scan measurements in plain water as well as transskull, we have documented a range of tFUS beam distortions for a variety of target points and access angles. In this paper, we present quantitative measurements of tFUS distortions due to skull aberrations at different operating frequencies. In addition, refocusing results for a variety of target points at different frequencies within the transducer bandwidth are presented in terms of improvement in focusing gain. Dual-mode ultrasound array (DMUA) prototype (64 elements, concave with 40-mm radius of curvature) was used. Skull samples were extracted from animal subjects that have undergone tFUS treatments using the DMUA prototype were utilized. Experiments were performed at a set of 31 discrete frequencies in the range 2.0 MHz–5.0 MHz. A needle hydrophone was used to measure the pressure waveforms at the target locations. The element transmission efficiency varied as a function of frequency in a nonmonotonic manner with a range of 5–15 dB variation for the different target points. The array focusing gain also varied nonmonotonically suggesting the need for broadband refocusing.
Broadband transskull multi-focus wavefront synthesis
Authors: O'Brien Parker D. , Liu Dalong , Ebbini Emad S.
Published: April 2018

Multiple-focus pattern synthesis using ultrasound arrays has been previously demonstrated. Furthermore, an optimal synthesis method was shown to provide well-behaved solutions. This method creates predefined focus patterns at a single frequency for an ultrasonic array operating in continuous wave. In this paper, we extend the approach to the broadband case using orthogonal frequency-division multiplexing (OFDM). A broadband multiple-focus pattern is formed by summing the results of the synthesis algorithm at a set of discrete frequencies within the transducer bandwidth. The OFDM approach allows for achieving a predictable focusing gain at the target point(s) due to the waveform orthogonality. Outside the target region, the different frequency components can be expected to provide a larger degree of destructive interference. Hydrophone scans of multiple-focus patterns in plain water as well as transskull were performed using a phased array with a multichannel arbitrary waveform generator. The array has a 3.5 MHz center frequency with a 6-dB bandwidth in the range 2.2 MHz–4.8 MHz. The skull samples were obtained from 300 to 350 g rats that were used in other in vivo experiments. The results show greater focus resolution than for any single frequency pattern while reducing the interference patterns outside the target region.
Acoustical experimental design for ultrasonic neurostimulation on rodents
Authors: Lani Shane W. , Congedo Marina , Hwang Grace , Rosenberg Allan
Published: April 2018

While the mechanisms of ultrasonic neurostimulation are still unknown, this method has been successfully shown on rodents from a variety of research groups. While the results are compelling, there has been limited work in characterizing the acoustic fields that are generated and ultimately delivered to the rodent brain which is important in order to determine the underlying neurostimulation mechanism. This presentation details some of the acoustical experimental design processes that are being undertaken at JHU/APL as well as our current progress in the rodent ultrasonic neurostimulation. The experimental design utilizes a complementary process of both simulation and experimentation verification to determine the expected delivered acoustic wave field. The simulation encompasses the full propagation path from the single element focused transducer, through an acoustic waveguide and skull, to the treatment location. This work uses a focused transducer with a center frequency of 0.5 MHz with several different waveguides that are characterized in our calibration tank with regards to intensity over space. Each of these waveguides is modeled and compared relative to the focal spot size and intensity delivered to the focal spot. These measurements are used to select an optimal waveguide which is used in the model to determine the expected performance of the full system. The presented results compare the performance of the waveguides and their impact on ultrasonic delivery to the rodent brain.
The Technical Committee on Musical Acoustics: Diverse membership with a common interest
Authors: Cottingham James P.
Published: April 2018

The Technical Committee on Musical Acoustics is concerned with the application of science and technology to the field of music. Topics of current interest include the physics of musical sound production, music perception and cognition, and analysis and synthesis of musical sounds. TCMU is an interdisciplinary committee with ties to architectural, psychological and physiological, signal processing, speech, physical, and structural acoustics. Members of the committee represent a variety of backgrounds and interests, yet are united by a common interest in understanding all aspects of the science of music.
An introduction to the Engineering Acoustics Technical Committee
Authors: Scanlon Michael V.
Published: April 2018

The Engineering Acoustics Technical Committee's scope encompasses the theory and practice of creating tools for investigating acoustical phenomena and applying knowledge of acoustics to practical utility. This includes the design and modeling of acoustical and vibrational transducers, arrays, and transduction systems in all media and frequency ranges; instrumentation, metrology, and calibration; measurement and computational techniques as they relate to acoustical phenomena and their utility; and the engineering of materials and devices. The breadth and scope of EATC’s mission is an enabler to the other committees and to the interests of every member.
An introduction to research topics in underwater acoustics
Authors: Sagers Jason D.
Published: April 2018

The Acoustical Society of America Technical Committee on Underwater Acoustics (UW) investigates sound wave phenomena in marine environments, including oceans, lakes, and rivers. Research interests span a broad spectrum from the measurement and modeling of acoustic propagation and scattering, to the detection and characterization of underwater sound, to signal processing algorithms and statistics. This diverse technical committee also shares interests with Animal Bioacoustics (AB), Acoustical Oceanography (AO), and Signal Processing (SP). This talk will highlight a few past and present research topics in underwater acoustics, emphasizing the important role of sound as a tool in subsea research and exploration.
Overview of animal bioacoustics
Authors: Erbe Christine
Published: April 2018

Research in Animal Bioacoustics includes (1) animal sounds, communication, biosonar, and associated behavior; (2) sound production anatomy and neurophysiology; (3) auditory capacities and mechanisms, anatomy, and neurophysiology; (4) acoustic phylogeny, ontogeny, and cognition; (5) acoustic ecology, acoustic characterization of habitats, and effects of sound on animals; (6) passive acoustic tools and methods, hardware and software, for detection, classification, localization, tracking, density estimation, and behavior monitoring; and (7) active acoustic tools and methods, including animal-tracking sonars and echosounders, acoustic tags, pingers, deterrent devices, etc. Study species include birds, terrestrial mammals (in particular, bats), marine mammals, amphibians, reptiles, fishes, insects, and crustaceans. Researchers have diverse backgrounds ranging from acoustics, engineering, mathematics, and physics, to biology and zoology. We pool our expertise in this truly interdisciplinary field of Animal Bioacoustics.
Biomedical acoustics: From diagnostic imaging to treating brain disorders
Authors: Maruvada Subha
Published: April 2018

The Technical Committee on Biomedical Acoustics (BATC) is one of the most diverse groups in the Acoustical Society of America. BATC is comprised of scientists and engineers who study a wide range of biomedical applications using ultrasound from imaging fetuses to ablating fibroids and treating brain disorders. Diagnostic ultrasound has expanded to include exciting new techniques such as shear wave elastography and opto-acoustic imaging. Therapeutic ultrasound applications include physiotherapy, lithotripsy, as well as the treatment of tumors via thermal ablation, i.e., HITU, or mechanical ablation, i.e., histotripsy. The most recent developments in therapeutic ultrasound involve neuromodulation and transcranial magnetic resonance guided focused ultrasound for the treatment of various brain disorders, including essential tremor, neuropathic pain, and Parkinson’s disease. The ability to temporarily open the blood-brain barrier using focused ultrasound has been demonstrated in animals and, more recently, in humans. Opening of the blood-brain barrier could allow the transmission of drugs to treat brain diseases. Diagnostic and therapeutic ultrasound applications continue to advance the field of medicine and are integral to the advancement of both diagnosis and treatment of debilitating diseases.
Introduction to the structural acoustics and vibration technical committee
Authors: Koch Robert M.
Published: April 2018

The Structural Acoustics and Vibration (SAV) Technical Committee is a broad group of scientists and engineers sharing a common interest and shared stewardship in the health and advancement of the SAV technical discipline. Structural acoustics may be defined as a multidisciplinary coupled field of physics usually referring to the characterization of either (1) the sound power emitted by a vibrating structure subjected to external dynamic excitation or (2) the vibrational response of structures excited by incident sound fields or fluid excitation. While the fundamental scientific study of the underlying SAV physics is certainly important to SAV practitioners, there is also interest on the practical application of the prediction, control, and potential reduction of the vibroacoustic response of given structural acoustic systems. This paper first provides a fundamental definition of the underlying physics behind the SAV technical discipline. The many categories and subdivisions within the general SAV area are then addressed, along with illustrations of the broad array of scientific and engineering real-world applications in the field. Following that, examples of interesting career options as well as exciting new research areas in SAV are presented. Finally, the paper concludes with information regarding the makeup, functioning, and administrative philosophy of the SAVTC.
It is like ESP without the E: An Introduction to the Speech Communication Technical Committee
Authors: Munson Benjamin
Published: April 2018

Speech communication (SC) is a quintessentially human behavior. Scholars in the SC Technical Committee conduct research on three broad areas: the production of speech, the perception of speech, and the machine processing of speech. We study people across the globe and across the entire lifespan. Our work includes people with and without speech, language, and hearing impairments. This brief talk will highlight three recent projects by SC TC members that illustrate the breadth of our work. We will review research on how speech style affects memory for speech, how ultrasound can be used to measure tongue movement during speech, and how speech synthesis can be used to estimate articulatory movements from acoustic records of speech. We hope that this presentation will encourage students and new members from our society's many technical committees to learn more about how our work in the SC TC complements research and scholarship in many different fields of acoustics.
Signal processing everywhere you look
Authors: Michalopoulou Zoi-Heleni
Published: April 2018

Whether designing an auditorium, interpreting a marine mammal song, analyzing a sonar signal, or extracting information from ambient noise, signal processing is there. With active research in the field, signal processing provides a multitude of tools that are critical for solutions of complex acoustic problems. With time-series analysis, time-frequency representations, higher-order statistics, model-based and Bayesian processing, compressed sensing, and many other approaches, acoustic signal processing brings together physics, mathematics, and statistics, theory and computation, for the better understanding of acoustical phenomena. The diversity of the field is evidenced by the fact that members of the Technical Committee on Signal Processing in Acoustics also have membership in a multitude of other technical committees: underwater acoustics, acoustical oceanography, animal bioacoustics, and architectural acoustics, to name a few. Additionally, many special sessions at Acoustical Society Meetings are cosponsored by the Technical Committee on Signal Processing in Acoustics, proof that signal processing is everywhere you look. It is this diverse field that we explore in this talk, providing an overview of current research in a number of areas.
SignalMaster—An open hardware and software system for speech and signal processing
Authors: Davies Patrick , Delgado Rafael E.
Published: April 2018

A portable speech and signal processing system was developed using a TMS320C6748 Digital Signal Processor (DSP) with two input and output channels with 32 bit Analog-to-Digital (AD) and Digital-to-Analog (DA) converters. Lithium-ion batteries provide up to 10 hours of freestanding operation. The system may also be used while connected to a personal computer (PC). Special boot loading code and an interface protocol was developed in order to allow communications and standardize the transfer of instructions and data between the DSP hardware and PC through a Universal Serial Bus (USB) interface cable. In addition, a PC-based user application interface high-level language dynamic link library was also developed to enable development of a wide range of applications. The library provides functions for user developed applications to communicate with the hardware and be able to upload C language programs into the DSP system. This allows for different programs to be uploaded in order to reconfigure the processing algorithms being executed for any experiment at any time. DSP and PC-based software source code examples provide users with the ability to develop their own user specific applications. Examples were developed to demonstrate the implementation of hearing aid amplification, filtering, and noise cancellation in real time.
Audiologic evaluation of the tympan open source hearing aid
Authors: Alexander Joshua M. , Clavier Odile , Audette William
Published: April 2018

The “Tympan” open source hearing aid (Creare LCC) was developed in response to needs identified by the 2014 Open Speech Signal Processing Platform Workshop hosted by NIH. The Tympan Phase I prototype is a neck-worn device with external microphones and headphones implemented on a Teensy 3.6 development board and Arduino software platform. Custom-designed electronics for audio input acquisition, digital signal processing, power management, and wireless communication allows expert users to create new algorithms directly in firmware. Operating in parallel, a custom software interface allows “occasional” users with the necessary support to modify easily parameters of existing algorithms. A variety of electroacoustic analyses, including throughput delay, amplitude compression input/output curves and time constants, harmonic distortion, internal noise, frequency response, and other real-ear measurements were performed on the Phase I prototype using commercial hearing aid analyzers and compared to today’s premium hearing aid products. Overall, the results indicate that the Tympan Phase I prototype performs similarly to an actual hearing aid on these metrics. Results from an early Phase II prototype will also be reported. [Work supported by NIH NIDCD Grant #1R44DC015445-01 to Creare LLC.]
An open computational platform for low-latency real-time audio signal processing using field programmable gate arrays
Authors: Snider Ross K. , Casebeer Christopher N. , Weber Raymond J.
Published: April 2018

Field Programmable Gate Arrays (FPGAs) provide flexible computational architectures that are ideal for digital signal processing (DSP). With support of a NIH/NIDCD SBIR grant, we are developing an open FPGA platform for the speech, hearing, and acoustics research communities. The advantage of using FPGAs in a computational platform over conventional CPU approaches is the ability to implement low-latency high-performance signal processing with deterministic latencies. The hardware portion of the platform includes an audio codec and an Intel System-on-Chip (SoC) FPGA that contains ARM CPUs alongside the computational fabric that allows custom data plane designs. Development uses Mathwork’s Simulink that allows exploration and simulation of signal processing algorithms. Once a Simulink model has been developed to implement audio processing in either the time domain or frequency domain, VHDL code can be generated that implements the desired signal processing. The VHDL code is then implemented in the FPGA computational fabric where the FPGA functions as a real-time signal processor. We are currently soliciting ideas/feedback from the speech, hearing, and acoustic communities as to what features they would like to see in the next iteration of the open FPGA-based computational platform. [NIH/NIDCD R44DC015443: www.openspeechtools.com]
Open portable platform for hearing aid research
Authors: Pavlovic Caslav , Hohmann Volker , Kayser Hendrik , Wong Louis , Herzke Tobias , Prakash S. R. , Hou zezhang , Maanen Paul
Published: April 2018

The NIDCD has recently funded a number of projects to develop portable signal processing tools that enable real-time processing of the acoustic environment. The overarching goal is to provide a large group of researchers with the means to efficiently develop and evaluate, in collaborative multi-center environments, novel signal processing schemes, individualized fitting procedures, and technical solutions and services for hearing apparatus such as hearing aids and assistive listening devices. We report on the specific goals and results of two such projects. In one of them (R01DC015429), an open source software platform for real-time runtime environments is developed: The open Master Hearing Aid (openMHA). It provides an extendible set of algorithms for hearing aid signal processing and runs under Linux, Windows, and Mac operating systems on standard PC platforms and on small-scale ARM-based boards. An optimized version of openMHA is provided for the companion SBIR project (R44DC016247), which is a portable, rigid, versatile, and wearable platform featuring an ARM Cortex®-A8 processor. The resulting Portable Hearing Aid Community Platform consists of both hardware elements to provide the advanced desired functionality and software routines to provide for all the features that researchers may need to develop new algorithms.
A Green’s function parabolic equation description of infrasound propagation in an inhomogeneous and moving atmosphere
Authors: Muhlestein Michael B. , Ostashev Vladimir E. , Wilson D. K.
Published: April 2018

Accurate atmospheric infrasound propagation models must account for variations in local sound speed and ambient flow. This paper describes and demonstrates a method to extend the Green’s function parabolic equation (GFPE) to account for 3D high Mach number ambient flow in addition to an inhomogeneous atmosphere. Predictions of infrasonic propagation using the resulting GFPE model are then compared with predictions using other models.