bluuebunny/crossref_metadata_2025 huggingface dataset:
A soil-plate-oscillator apparatus for research projects and student demonstrations
Authors: Pineda Brown Melissa , Taliaferro Brianna D. , Korman Murray S.
Published: May 2016

In studying the complex vibration of compliant buried objects in soils, a simplified model apparatus called the “soil-plate-oscillator” (SPO) has been useful in understanding resonant behavior. The SPO is an open column of granular medium supported at the bottom by a thin circular clamped elastic plate. A rigid vertical circular sleeve (sidewall) keeps the soil in a circular column. Two 4.5 in. I.D. plastic PVC closet flanges are used to clamp a 1/8 in. thick acrylic plate. The elastic plate is driven from below by an AC coil located coaxially below a rare earth magnet (fastened to the plate’s underside at the center). An amplified swept sinusoidal chirp drives the coil. A small accelerometer, attached to the magnet, generates a charge amplified signal fed into a spectrum analyzer placed in the swept sine mode. Results for (a) dry sifted masonry sand and (b) 6 mm glass spheres are compared. In both experiments, the resonant frequency versus granular mass loading first decreases (reaching a minimum) and then increases with further loading due to the granular flexural stiffness which overcomes the mass loading effects. [R. A. Guyer and P. A. Johnson, Nonlinear Mesoscopic Elasticity, Wiley, 2009] discusses spherical granular media in Hertzian contact.
Modeling acoustic landmine detection using a soil-plate oscillator
Authors: Nguyen Miahanna K. , Lewis Joshua M. , Korman Murray S.
Published: May 2016

In laboratory acoustic landmine detection experiments a plastic cylindrical drum-like simulant is buried in a soil (or sand) tank. Airborne sound, generated from two subwoofer loudspeakers (located above the soil), drive the soil particles and subsequent particle vibration over the compliant top plate of the simulant. Measurements of tuning curve soil surface vibration particle velocity versus frequency are recorded for various scan locations across the soil surface in an effort to profile the buried simulant. Measurements of resonances “off the target” are also included in this study. The results can be modeled using a soil-plate-oscillator (SPO) apparatus. The SPO involves a vertical thick-wall cylindrical column of granular medium (sand, soil, pebbles, light density edible granular material like wheat germ or even uncooked brown rice) that is supported by a thin circular elastic (acrylic) plate (8 in. diameter, 1/8 in. thick) that is rigidly clamped at the bottom of the column. A small accelerometer placed on the granular surface (or a laser Doppler vibrometer) measures tuning curve results across the surface using a sweep spectrum analyzer. Profiles are compared for both the SPO and the simulant in an effort to model the results in the later—more complicated case.
Ultrasonic scattering at 25 kilohertz in air by a hexagonal array of slender long rigid rods arranged to form a porous cylindrical target
Authors: Gong Joshua R. , Rivera Adela S. , Korman Murray S.
Published: May 2016

Experiments were performed in the USNA Acoustics Lab using 30 cycle transient-bursts at 25.8 kHz in air (c = 340 m/s, ρ = 1.2 kg/m3) to measure the backscattering of the ultrasonic pulse from a hexagonal array of stainless steel rods (diam d = 0.089 cm, length l = 91 cm). The lattice parameter was a = 0.22 cm. To construct the array, the rods were placed within the holes of two 30.5 cm square thin perforated aluminum sheets suspended 88 cm apart. A third non-perforated sheet hung 1 cm below prevented the rods from falling through. The diameter of the cluster was D = 10 cm. The filling fraction of the lattice was f = 0.15.The transmitting array (located 1.5 m from the cluster) was an eight-element discrete ring of diam 5.5 cm that produced an interference null at + /− 10 degrees and a −10 dB down minor lobe at + /− 17 degrees. A single 1 cm diam receiver element was located at the center of the ring. In a strip-map configuration, the transmitted beam translated 60 cm across the target recording echoes at 1 cm increments. The target’s effective speed and density were 0.93c and 1.35ρ, respectively. See D. Torrent et. al. [Phys. Rev. Lett., 96, 204302 (2006)].
Teaching the descriptive physics of string instruments at the undergraduate level
Authors: Anderson Brian E. , Gee Kent L. , Neilsen Tracianne B.
Published: May 2016

At Brigham Young University, a general education course introduces students to the basic descriptive acoustic principles of music, speech, and audio. A third of this course focuses on the physics of musical instrument families. Three of these families include bowed string, plucked string, and struck string instruments. The concepts of driven systems and freely vibrating systems are taught, including the consequences of these excitation conditions. A hands-on lab for the course enables students to explore how the length, density, and tension of the string change the fundamental frequency. An in-class demonstration highlights the role of inharmonicity on the partial frequency values for these string instrument families. The combination of hands-on activity and demonstration aids the students in comprehending the basic acoustic principles behind string instruments and the reason for varying levels of inharmonicity between these instrument families.
Things I learned while teaching a graduate level course on the acoustics of musical instruments
Authors: Russell Daniel A.
Published: May 2016

In spring 2013, I taught a graduate level course on the acoustics of musical instruments. A prerequisite of two courses on the fundamentals of acoustics and vibration allowed us to explore details and mathematical complexities. Due to time constraints and the decision to delve deep into details rather than provide a broad overview, the course focused on wind and stringed instruments. Both types of instruments were explored through the generator-resonator-radiator paradigm. We discussed nonlinear generators for winds (lip reed, mechanical reed, and air-reed) and realistic initial conditions for strings (finger plucked, struck by a nonlinear hammer, and the stick-slip bowing action); realistic resonators for winds (input impedance and the effects of holes, horns, and viscous losses) and strings (realistic boundary conditions and coupled motion); and radiation (bells and soundboards). This paper will describe some of the Mathematica animations used to illustrate the effect of tone holes on the input impedance of a woodwind instrument, the effect of mouthpiece volume on the input impedance of brass instruments, and the motion of plucked, struck, and bowed strings. We will discuss the challenges of teaching a graduate level course, and what I would do differently the next time I teach it.
Developing and teaching an interdisciplinary musical instrument design course at the Cooper Union
Authors: Lawless Martin S. , Baglione Melody , Sidebotham George W.
Published: May 2016

Design is a major component of every student’s educational experience at the Cooper Union, a small university in New York City with architecture, art, and engineering schools, and yet, design courses including students from all three schools are uncommon. In the 2012–2013 academic year, a Musical Instrument Design course was proposed to encourage the collaboration of architecture, art, and engineering students. Musical acoustics appealed to these three types of students since the subject inherently combines aesthetic and physical principles. The course intended to accommodate the students’ wide range of music and physics backgrounds with lectures on music theory, acoustics and vibration, and the design of traditional instruments. Live demonstrations attempted to inspire hands-on learning, and in-class presentations facilitated the discussion of the diverse perspectives of the class. The course also included an outing to the machine shop where the class collaborated on making PVC flutes for each student. For a final project, the students were required to design and create a musical instrument. The Musical Instrument Design class was offered for zero credits in the Spring 2013 semester to gauge overall interest. Fourteen students enrolled in the course and maintained a good attendance throughout the semester.
Students and power tools: Lessons learned from building recorders in a Physics of Music class
Authors: Dostal Jack
Published: May 2016

In my divisional (general education) course “The Physics of Music,” my students each design and build a simple recorder using PVC pipe. The process is borrowed from “Flute Design” and “Flute Construction” labs by Peter Hoekje at Baldwin-Wallace University, as well as Pete Kosel’s flute hole calculator. The lab has been modified slightly to fit the constraints of our class, and is done over the course of two lab periods. We have tried several variations on the process and made plenty of mistakes. Typically, our students have little to no experience using power tools or shop equipment. Consequently, this tends to be one of the most adventurous labs of the term. In this talk, I describe some of the practical things I’ve learned and mistakes I’ve made while watching and helping my students build recorders. Among these are difficulties in creating fipples and knife edges, adventures in hole-drilling, finding reasonable finger hole positions, and student reaction to the finished product.
Engaging musical acoustics instructors beyond the members of the Acoustical Society of America
Authors: Morrison Andrew C.
Published: May 2016

The members of the Technical Committee on Musical Acoustics (TCMU) of the Acoustical Society of America (ASA) have demonstrated their commitment to education in acoustics regularly by organizing and cosponsoring numerous education-related sessions at ASA meetings. Musical acoustics as a topic for general education science courses is a popular offering at many colleges and universities. A brief survey of the musical acoustics course offerings at various colleges is presented. Many of these courses are taught by instructors who have not interacted with TCMU members or attended ASA meetings. It is possible that the musical acoustics community is missing out on opportunities to interact with a population of educators who share our interests. Our community should be looking for ways to engage the instructors of musical acoustics courses in dialogue which is mutually beneficial; members of the TCMU may find that they will discover new ideas for teaching musical acoustics from beyond the ASA membership.
Automated detection and cataloging of global explosive volcanism using the International Monitoring System infrasound network
Authors: Matoza Robin S. , Green David N. , Le Pichon Alexis , Fee David , Shearer Peter , Mialle Pierrick , Ceranna Lars
Published: May 2016

Explosive volcanic eruptions are among the most powerful sources of infrasound observed on earth, with recordings routinely made at ranges of hundreds to thousands of kilometers. These eruptions can also inject large volumes of ash into heavily traveled aviation corridors, thus posing a significant societal and economic hazard. Detecting and counting the global occurrence of explosive volcanism helps with progress toward several goals in earth sciences and has direct applications in volcanic hazard mitigation. This project aims to build a quantitative catalog of global explosive volcanic activity using the International Monitoring System (IMS) infrasound network. We are developing methodologies to search systematically through IMS infrasound array detection bulletins to identify signals of volcanic origin. We combine infrasound signal association and source location using a brute-force, grid-search, cross-bearings approach. The algorithm corrects for a background prior rate of coherent infrasound signals in a global grid. When volcanic signals are identified, we extract metrics such as location, origin time, acoustic intensity, signal duration, and frequency content, compiling the results into a catalog. This work represents a step toward the goal of integrating IMS data products into global volcanic eruption early warning and notification systems.
An innovative technique to probe the middle and upper atmosphere
Authors: Assink Jelle D. , Smets Pieter , Evers Läslo , Le Pichon Alexis
Published: May 2016

The middle atmosphere has gained more and more importance for the purpose of weather and climate prediction, since increasing evidence indicates that the troposphere and stratosphere are more closely coupled than assumed before. Significant effort has been made toward a more comprehensive representation of the atmosphere to better capture the stratospheric variability as well as the stratospheric-tropospheric interactions, for example, during Sudden Stratospheric Warming (SSW) events. Despite these advances, the upper layers of the atmosphere have remained a region that is difficult to monitor. Over recent years, new developments in the field of infrasound have lead to an innovative method for evaluating numerical weather prediction models. In this presentation, the general technique will be described and a case study will be presented in which stratospheric forecasts of the 2013 major SSW are evaluated.
Using detection theory to analyze human decision making and sensory processing
Authors: Gallun Frederick J.
Published: May 2016

On the 50th anniversary of the publication of Green and Swets’ book “Signal Detection Theory and Psychophysics,” it is fitting to revisit the question of how detection theory models of human decision making can improve our understanding of sensory processing. Classical psychophysics, as conceived by Fechner in 1850, trusts the observer to report sensory experiences without bias. The innovation of signal detection theory (SDT) was to develop methods that do not require the observer to have introspective awareness of internal sensations. Since its introduction, SDT has inspired experimentalists in many fields, and so now it is appropriate to simply refer to “detection theory” (DT) as the models are appropriate to a wide range of experiments, many of which do not involve signals in noise per se. Data from a previously published intensity discrimination task relying upon working memory (Gallun et al., 2012) will be examined in greater detail to show the techniques and benefits of a detection theory approach to the analysis of human decision making.
Generalized linear mixed models in hearing science
Authors: Bharadwaj Hari M.
Published: May 2016

Linear mixed-effects models (LMEs), by virtue of allowing for the quantification of both random effects (e.g., associated with sampling of subjects) and the effects of fixed predictor variables, provide a powerful statistical modeling framework that can accommodate a large number of common experimental designs used in hearing science. Examples of designs for which LMEs are suitable include repeated-measures designs, longitudinal studies, and multilevel designs. An extensive literature of robust methods exists for fitting such models for normally distributed responses. On the other hand, often, data in hearing science experiments are binary (e.g., detected or missed), proportions, or counts (number of correct responses) and are better modeled using non-normal distributions (e.g., binomial). Generalized linear mixed models (GLMMs) provide a framework to retain the advantages of LMEs in modeling random effects by modeling the non-normal response variables using LMEs through (nonlinear) link functions. In this presentation, using example simulated and real psychophysical (attention task performance) and physiological data (OAEs, EFRs), I will introduce GLMMs and discuss the great flexibility they offer, and the challenges involved in parameter estimation and inference. I will also point to emerging methodological options and software packages for using GLMMs.
Nonparametric statistical approaches to neuroimaging data
Authors: Noyce Abigail L. , Sekuler Robert
Published: May 2016

Neuroimaging, including electroencephalography (EEG), magnetoencephalography (MEG), and functional magnetic resonance imaging (fMRI), is a rich source of information, allowing perceptual researchers measure neural responses to sensory inputs. Scalp EEG’s high temporal resolution makes it a method of particular interest to auditory scientists who want to identify (and possibly model) the spatial and temporal extent of a difference between the two conditions. Analyzing neuroimaging data, however, poses several challenges. First, collecting data from tens or even hundreds of sensors and hundreds of time points creates a multiple comparisons problem. Second, neuroimaging data are often quite noisy (as is the brain itself). Finally, imaging data distributions are often incompatible with the assumptions of traditional parametric statistics—most notably, data are often non-normal, and with unequal variance. We illustrate strategies for addressing these challenges in the context of a selective attention study. EEG was recorded while subjects attempted to report a central target in the presence of either standard or oddball distractors. Using clustering and Monte Carlo permutation, we showed that neural responses to the distractors elicit an oddball effect.
Direct and transient analyses of the Schur complement for complex vibrating systems
Authors: McDaniel James G. , Wixom Andrew S. , Rodriguez Rodolfo
Published: May 2016

We are interested in computing the steady-state response of coupled vibrating systems over a frequency band. For each system, the present coupling analysis requires the impedance matrix that relates forces and velocities at the coupled or externally forced degrees of freedom at all frequencies of interest. Algebraic manipulation of each system's full impedance matrix yields the desired impedance matrix in the form of a Schur complement. The present work surveys and compares two approaches for computing the Schur complement, with a particular focus on the effects of damping. The direct analysis computes the Schur complement in the frequency domain, which requires a linear solve of a large system with several forcing vectors at each frequency. The transient analysis computes the impulse responses of the coupled degrees of freedom by numerical integration. This is followed by a Fourier transform that yields the Schur complement. Approaches for choosing the most efficient analysis are presented, along with numerical examples that illustrate and compare both approaches.
Prediction of broadband high-frequency acoustic reflection and transmission from elastic plates with structural discontinuities
Authors: Villa Mauricio , Bliss Donald
Published: May 2016

A model for the acoustic reflection and transmission for flexible boundaries with structural discontinuities is developed. The system studied is an infinite, fluid loaded plate with periodically fixed constraints that is driven by an incident acoustic field. To treat the local discontinuities of the plate, the coupled structural/acoustic problem is treated by applying the method of Analytical-Numerical Matching (ANM). The ANM framework, which separates the problem into a global numerical solution and a local analytical solution, offers an approach to handle mathematical difficulties associated with the coincidence frequencies of the system. Accurately treating the rapid spatial variation around the discontinuities improves the overall accuracy and convergence of the computational analysis to predict the resulting pressure levels. Results for an infinite plate with discontinuities are compared to a baffled plate with a fluid loading correction introduced to the structural wavenumber. Simple closed-form band-averaged directivity patterns are determined. This approach facilitates an energy-intensity reformulation of the structural and acoustic equations, allowing for the possibility of formalizing the couplingbetween energy flows in the acoustic and structural systems. The overall goal is to develop efficient first principles computational models for more accurate modeling of broadband structural-acoustic reflection and transmission between coupled acoustic spaces.
When an offshore cylindrical pile is impacted axially, the resulting wall vibration and underwater radiated sound pressure are insensitive to which thin shell theory is selected
Authors: Hall Marshall V.
Published: May 2016

When a pile is impacted axially, a pulse of axial and radial vibration travels downwards and undergoes continued reflections at the toe and head. If a pile is to be treated as a thin cylindrical shell then producing a model for radiated sound pressure requires a particular “thin shell theory” to be selected. There are 12 such theories, as catalogued in Leissa’s monograph “Vibration of shells.” Four have been selected: the Membrane, Donnell-Mushtari, Flugge, and Epstein-Kennard theories (the last is the most intricate of the 12). An offshore pile with 25.4-mm wall thickness and 381-mm radius (6.7%-ratio) is modeled. Since the pile head is above the water surface, aerial radiation strongly attenuates the vibration of the immersed pile near the pile’s ring frequency (2.1 kHz). Spectra of radial vibration and underwater radiated sound pressure are computed up to 10 kHz using each of the four theories and found to be the same, except near the ring frequency. When the calculations are repeated for a similar pile with a wall three times thicker (no longer a thin shell), the Flugge results are higher than the other three by an amount that increases to 2 dB as frequency increases to 10 kHz.
Effects of internal acoustic coupling on the response of a base-excited hollow structure
Authors: Schultz Ryan , Tipton Greg
Published: May 2016

Traditionally, structural dynamic simulation predictions for hollow structures do not include internal acoustic volumes. This is the case for two reasons. First, it can be difficult to create a volume mesh of complicated internal cavities, and this additional volume would drastically increase the size of the model. Second, it is often blindly assumed that acoustic coupling is not important for structures with anything but thin walls. However, if the structural and acoustic modes are compatible, that is, the modes have similar frequencies and shapes, then the interaction between the structure and the enclosed acoustic volume will occur and can have an effect on structural response. The magnitude of this coupling effect is demonstrated here by examining the structural response predictions for a finite element model of a hollow structure with and without the acoustic volume in place. When a base excitation is applied at a frequency and location to excite compatible modes, the response predictions are seen to be drastically different if the acoustic volume is included. The frequency response results of the coupled finite element simulations will be compared with those of the classic two degree of freedom dynamic vibration absorber, showing the effect of frequency ratio and damping on the structural response.
Energy flux streamlines for an ensonified fluid sphere near a rigid boundary: Implementation and testing
Authors: Dean Cleon E. , Braselton James P.
Published: May 2016

Progress in the implementation and testing of routines to compute the energy flux [J. A. Mann III, et al., J. Acoust. Soc. Am. 82, 17–30 (1987)] and energy flux streamlines [D. M. F. Chapman, J. Acoust. Soc. 124, 48–56 (2008)] for the problem of an ensonified fluid sphere near a rigid boundary are presented. The problem is isomorphic via the method of images to the problem of interactive scattering between two identical fluid spheres. Trinks provided an analytical solution to this problem in 1935 [W. Trinks, Ann. Phys. 414, 561–590 (1935)]. However, his solution is mathematically intractable for larger spheres due to the complexity of his translational addition theorem for spherical harmonics. Later, researchers Cruzan [Quart. Appl. Math. 20, 33–40 (1962)] and Liang and Lo [Radio Science 2, 1481 (1967)] simplified this translational addition theorem, making it feasible to solve the problem with larger spheres. This work follows Bruning and Lo [Tech. Rep. 69-5 (Antenna Laboratory, Univ. of Illinois, Urbana, IL 1969)], correcting typos in that work to implement efficient algorithms for acoustical scattering.
Effects of auditory training on cochlear implant users’ gender categorization
Authors: Kwon Bomjun J. , Fu Qian-Jie
Published: May 2016

Nowadays, the benefits of cochlear implants (CIs) for individuals with a substantial degree of hearing loss are widely demonstrated in clinical applications in terms of both speech recognition and speech production. However, a body of evidence indicates CI users’ compromised ability to accurately categorize gender of the voice (e.g., Fuller et al., J. Assoc. Res. Otol. 15, 1037–1048, 2014), which may be an obstacle to overcome to improve executive functions for communication with the device. While it has been known that CI users are capable of utilizing the fundamental frequency (F0) of the voice as the primary determinant of gender categorization, poor differential selectivity in F0 with the device attributes to the compromised ability. Another vocal characteristic, vocal tract length (VTL), which is known to play an important role in gender categorization in normal hearing (NH) listeners, is largely ignored in CI users. Considering that the VTL information, grossly reflected on formants, may be transmitted through the device and perceived by CI users when presented in isolation, and that CI users, in general, highly utilize episodic context, proper auditory training of CI users with voice stimuli with F0 and formants covaried or independently varied might improve their gender categorization.
Jimmy Scott and the problem of gender in singing
Authors: Eidsheim Nina , Kreiman Jody E.
Published: May 2016

The voice of jazz performer Jimmy Scott raises interesting questions of how gender is marked (or not marked) in singing voice. Scott was born with Kallman’s Syndrome, which affects male hormonal levels and prevents the onset of puberty. Although he self-identified as a “regular guy,” in his career he was presented as a novelty act—a boy who sounded like an adult woman—or paired with gender-ambiguous images. This paper explores Scott’s voice in comparison to male and female peers, with emphasis on the paradoxical role of falsetto in creating a male vocal image.
The influence of linguistic complexity and gender identity on /s/ variation in children
Authors: Munson Benjamin
Published: May 2016

Children, like adults, vary in the extent to which their speech conforms to stereotypical expectations for their biological sex. Previous research has examined this in boys with and without gender dysphoria (GD) [Munson et al., J. Acoust. Soc. Am. 137, 1995–2003 (2015); Munson, J. Acoust. Soc. Am. 138, 1895 (2015)]. Munson (2015) showed that 5–13 year old boys with GD were more likely than age-matched boys without GD to produce tokens of /s/ with a diffuse spectrum, consistent with a frontal, i.e., /θ/-like, /s/. This was based on an analysis of /s/ tokens from single word productions and from fluent sentence repetitions. The purpose of this presentation is to further examine the /s/ differences between these two groups of boys in single words, sentence repetitions, and spoken narratives elicited through a picture-description task. Analyses will examine whether the differences between the boys with and without GD are exaggerated in the narrative data, which offer more freedom for gender performativity than do single words and sentences. We will also examine whether the differences between groups are mediated by individual children’s language expressive language abilities, as measured by the objective complexity of their narratives, and by the overall accuracy of sentence repetition.
Recording of extended sound fields using spherical microphone arrays and a-priori knowledge of the sound source positions
Authors: Trevino Lopez Jorge A. , Wakayama Keigo , Sakamoto Shuichi , Suzuki Yo-iti , Takada Hideaki , Okamoto Manabu
Published: May 2016

The acquisition of comprehensive sound field information is a central topic in spatial acoustics. In conventional systems, recording devices must be located at the listener’s viewpoint. This research introduces a sound field recording technique for spherical microphone arrays which makes use of a-priori information regarding the distribution of sound sources. The proposal generates sound field descriptions for viewpoints that are located away from the recording device, as long as there are no sound sources between the target viewpoint and the microphone array. Sound field descriptions, a set of spherical harmonic expansion coefficients, are generated from the array signals. A translation operator, calculated from approximate source positions known in advance, is defined so as to shift the plane wave decomposition of the partial fields associated with each expansion coefficient. The proposed method is compared with an existing technique based on a different kind of translation operator traditionally used in implementations of the boundary element method. These operators require no a-priori information, but their region of validity is limited by the spherical harmonic expansion order. The conventional method achieves greater accuracy in the proximity of the recording array; however, the proposed method can generate sound field descriptions covering a much larger region.
A sparse recovery technique for the turbulent boundary layer wavenumber-frequency spectrum with non-uniformly spaced array of pressure transducers
Authors: Anderson Shaun D. , Gillett Philip W.
Published: May 2016

Historically, determination of wavenumber-frequency spectra of turbulent wall pressure fluctuations has employed the use of evenly spaced linear arrays of sensors. The reason for this is that even spacing of pressure samples in both the temporal and spatial domains facilitates analysis by direct application of 2-D Fourier transforms. The spacing of pressure measurements directly impacts the resolution of the resulting wavenumber-frequency spectra. This rigid spacing requirements of traditional methods may preclude analysis altogether with even a single sensor failure within the array. Rather than determining sensor locations based on the simplest analysis method, the sparseness of the wavenumber-frequency spectra can be leveraged to allow non-uniform sampling in both temporal and spatial domains. Sparse recovery techniques as an analysis tool for wavenumber-frequency spectra will be demonstrated both theoretically and experimentally for uniformly spaced arrays, uniformly spaced arrays with missing measurements, and randomly spaced arrays.
Azimuthal evaluation of formations near borehole: Numerical simulations and field examples
Authors: Liu Peng , Qiao Wenxiao , Che Xiaohua , Ju Xiaodong , Lu Junqiang
Published: May 2016

Azimuthal evaluation of formation properties near borehole is an important research direction of well logging technology, and we develop an innovative 3D sonic logging tool for that purpose. Except conventional measurements of monopole and dipole, this tool is added into an azimuthal transmitter station and a set of azimuthal receiver stations, all of which consist of eight piezoelectric vibrators in circumference to excite or acquire sonic waves. Our numerical simulation results show it can detect the heterogeneity of formations by using the measurement mode of azimuthal transmission and azimuthal reception that two types of P-wave with different velocities are found in the waveforms from some azimuths, but only one P-wave exists in other azimuths. Even two types of S-waves in one waveform are discovered when the formations are very hard. Similar phenomena for both P- and S-waves are also observed in field examples.
Preliminary characterization of surficial sediment acoustic properties and infauna in the New England Mud Patch
Authors: Lee Kevin M. , Ballard Megan S. , Venegas Gabriel R. , Wilson Preston S. , Dorgan Kelly M. , Reed Allen H. , Roosen Ellen
Published: May 2016

Biology is prevalent on and within many ocean bottom sediments. Organisms can include animals dwelling at or near the water-sediment interface or infauna living within surficial sediments. Bioturbation from burrowing, tube building, or other activities can have physical effects on the sediment acoustic properties. As part of the Sediment Characterization Experiment, a survey cruise was conducted in August 2015 in the New England Mud Patch, a region in the Atlantic continental shelf characterized by a layer of mud up to 12 m thick overlying a sandy subbottom. In addition to gravity coring operations to determine the properties of the mud layer, box cores and multicores were collected to examine the surficial sediment properties. Infauna were prevalent in the surficial sediment samples and were collected and characterized for body size, hardness, and potential for bioturbation or structuring. Shipboard measurements of shear and compressional waves were performed on the box core samples using time-of-flight measurements. Preliminary results from the infauna analysis and the shipboard acoustic measurements will be presented. [Work supported by ONR.]
Estimation of shear wave properties using Scholte wave inversions
Authors: Potty Gopu R. , Miller James H.
Published: May 2016

Shear speeds in semi-consolidated and consolidated shallow water sediments can significantly impact compressional wave attenuation and arrival times of acoustic normal modes. One of the most promising approaches to estimate shear speed is to invert the shear speed profile using the dispersion of interface waves (Scholte waves). The propagation speed of the Scholte waves is closely related to the shear wave speed over a depth of 1–2 wavelengths into the seabed. A geophone system for the measurement of these interface waves, along with an inversion scheme that inverts the Scholte wave dispersion data for sediment shear speed profiles and shear attenuation has been developed. A forward model based on the dynamic stiffness method has been developed and implemented in the inversion. A new Interface Wave Sediment Profiler (iWaSP) is being currently developed for the measurement of bottom properties such as shear speed and attenuation in the top 1–2 m of a variety of sediment types (including mud) with a wideband, vibratory source, and accelerometers with bandwidth up to 1 kHz. Inversions using data from previous deployments will be presented and proposed experimental designs for the proposed seabed experiment will be discussed. [Work supported by Office of Naval Research.]
Comparison of assorted diffusive room conditions
Authors: Bliefnick Jay , Wang Lily M.
Published: May 2016

A number of objective metrics have been proposed to quantify diffusive conditions in rooms, but less has been discovered about how perception of diffusion links to those metrics. In this project room impulse responses from a range of diffusive room conditions were recorded in the Mocap variable acoustics facility at Columbia College Chicago, which features 1200 sq. ft. of reversible absorptive/diffusive panels. Modifications to these surfaces were implemented to conduct two tests under multiple wall configurations. The first test concentrated on a direct reflection off of a 16 ft. x 8 ft. test wall, which was progressively changed from fully absorptive to fully diffusive. The second test utilized the entire facility by arranging the diffusers in multiple coverage percentages (10%–100%) and in three unique arrangements. A number of metrics have been calculated from the gathered impulse responses and compared, including those proposed to account for room diffusivity. Measured binaural room impulse responses are being used to generate auralizations for use in testing to discern when changes in the sound field become perceptible. Results to date will be presented.
Real & virtual: Lessons learned from modeling, measuring, and listening in a multi-purpose hall
Authors: Chu William , Cudequest Brandon
Published: May 2016

McKay Conant Hoover has guided a 2300-seat multipurpose venue through a series of modest renovations, each with tangible improvements, including expansion of the orchestra pit, provision for a proscenium eyebrow, reconfiguration and replacement of the orchestra shell, HVAC noise reduction, sidewall shaping, and finish selections to improve hall response for unamplified acoustics. However, much of the distinctive geometry of the hall by the renowned acoustician, Vern Knudsen, such as the broad, curved ceilings and walls, and the arching flying balcony, has remained unchanged since its opening in 1972. In 2014, an opportunity arose to investigate the acoustics of this space through a series of critical listening exercises, in-situ impulse response measurements, and virtual 3-D CATT modeling and auralizations. This paper will explore the challenges of comparing measured data, subjective preferences from actual music performances, computational model results, and listening tests through auralizations.
Asymmetric multi-frequency biosonar beam pattern of tongue-clicking bat, Rousettus aegyptiacus
Authors: Lee Wu-Jung , Falk Benjamin , Chiu Chen , Krishnan Anand , Moss Cynthia F.
Published: May 2016

The beam pattern of sonar signals emitted by echolocating animals, such as bats and toothed whales, directly influences the acoustic information available for guiding task-specific behaviors. The lingual echolocating bat, Rousettus aegyptiacus, emits broadband transient sonar clicks that resemble those of dolphins. The clicks are emitted in left-right pairs, with the maximum intensity slope of each signal pointing toward the target during navigation. However, detailed beam pattern characteristics of these lingual sonar clicks remain unknown. Using a loosely populated three-dimensional microphone array, we systematically characterize the multi-frequency beam structure of R. aegyptiacus in the entire azimuth-elevation domain. The bat’s head aim was recorded by an infrared high-speed motion-capture camera system. We show that the sonar beam of R. aegyptiacus tongue clicks is vertically elongated and exhibits an unusual multi-frequency structure that has not been described previously in the literature. Specifically, the high-intensity portion of the beam shifts medial in azimuth from the left and right click directions and downward in elevation with increasing frequency. Combined with close-up videos of mouth movement as the bats click, these results suggest a more sophisticated beam formation and steering mechanism than conventional simple aperture models.
Automatic fish sounds classification
Authors: Malfante Marielle , Dalla Mura Mauro , Mars Jerome I. , Gervaise Cedric
Published: May 2016

The context of this work is environmental monitoring. Specifically, we focus on acoustic systems for monitoring fish populations. By investigating the recorded sounds of fishes, it is possible to monitor the spatial and temporal evolution of fish populations. The aim of this work is to present an automatic fish sounds classification system. The solution we propose is new and based upon supervised machine learning (in particular, classification is performed by Random Forest). The features used in input of the learning algorithm come from an extensive state of the art in various domains of classification such as speech, music, animal calls, environmental acoustic landscape, and human induced noises. Our system is trained and tested on nighttime recordings from a 20 m depth seagrass habitat (Calvi, Corsica, France). From this study, we propose to consider 66 different features (shape and/or statistical description in time and frequency). Fish sounds are automatically classified into four different classes (drums, grunt, impulse, and FM), and our system reaches 94% of correct classification rate compared to 77% when considering MFFC features. In order to deal with large datasets and to study the evolution of fish populations, we are currently developing an approach based on dynamic classification with rejection (negative class).
Transcranial thermal ablation with a 230 kHz MRI-guided focused ultrasound system in a large animal mode
Authors: McDannold Nathan , Sutton Jonathan , Vykhodtseva Natalia , Livingstone Margaret
Published: May 2016

We evaluated the feasibility of thermal ablation in using a 230 kHz transcranial MRI-guided Focused Ultrasound (TcMRgFUS) system in three rhesus macaques. Thalamic targets were sonicated at 40–50s at 90–560 acoustic Watts. Focal heating sufficient to create an MRI-evident lesion was achieved in 4/6 targets where thermal dose exceeded 240 CEM43°C. Focal heating increased linearly as a function of the applied energy at a rate of 3.2±0.4°C/kJ (R²:0.81). Lesion sizes were consistent with 240 CEM43°C contours. The findings suggest that the lesions were consistent with thermal mechanisms. No evidence of cavitation-related petechiae were evident after sonication. Similar tests in macaques with a version of this system operating at 670 kHz (Hynynen et al., Eur. J. Radiol. 2006) measured skull-induced heating of 130°C/kJ/cm² of outer skull surface, more than twice of that measured here (63°C per kJ/cm²). While no or minimal focal heating was observed at 670 kHz, we reached ablation-level thermal dose values at 230 kHz. Thus, these preliminary results thus suggest that this low frequency system can expand the “treatment envelope” for TcMRgFUS.
Performance of a simulation-based phase aberration correction technique in transcranial ultrasound modeling
Authors: Christensen Douglas , Parker Dennis , Almquist Scott
Published: May 2016

Due to its irregular geometry and acoustic properties, the presence of the skull in transcranial focused ultrasound therapies can lead to considerable beam phase aberration, resulting in distorted focal spots. There are several possible techniques for correcting this phase aberration with a phased-array transducer, the most accurate of which (although invasive) is hydrophone-based time reversal. There are also simulation-based approaches, and here we exploit the time-advantages of the Hybrid Angular Spectrum (HAS) numerical method and apply it to two models of the skull: a 3D-printed plastic skull analog and a segment of a human skull for which a CT scan has been obtained. We compare the focused pressure patterns—obtained via hydrophone scans—for the cases of no phase correction, hydrophone-based phase correction, and simulation-based (HAS) phase correction. We show the degree to which the correction methods improve the focal spot quality, pressure amplitude, and localization accuracy. The very good results for the analog model compared to results for the skull segment indicate that better mapping of CT Hounsfield units to acoustic properties of the bone is needed. In addition, we use the simulation technique to predict the effects of beam steering and transducer/model misregistration on the effectiveness of aberration correction.
Computation of ultrasonic pressure fields in feline brain
Authors: Omidi Nazanin , Labuda Cecille , Church Charles C.
Published: May 2016

In 1975, Dunn et al. (JASA 58, 512–514) showed that a simple relation describes the ultrasonic threshold for cavitation-induced changes in the mammalian brain. The thresholds for tissue damage were estimated for a variety of acoustic parameters in exposed feline brain. The goal of this study was to improve the estimates for acoustic pressures and intensities present in vivo during experimental exposures rather than estimating them using linear theory. In our current project, the acoustic pressure waveforms produced in the brains of anesthetized felines were numerically simulated for a spherically focused, nominally f1-transducer (focal length = 13 cm) at increasing values of the source pressure at frequencies of 1, 3, and 9 MHz. The corresponding focal intensities were correlated with the experimental data of Dunn et al. The focal pressure waveforms were also computed at the location of the true maximum. For low source pressures, the computed waveforms were the same as those determined using linear theory, and the focal intensities matched experimentally determined values. For higher source pressures, the focal pressure waveforms became increasingly distorted; similar results were obtained with increasing frequency.
The state of the art in worship space acoustics
Authors: Bradley David T. , Ryherd Erica E. , Ronsse Lauren M.
Published: May 2016

Thoughtful acoustic design is essential for creating a worship experience full of awe and wonder. Worship space acousticians must grapple with differing acoustic requirements for speech and music, including a diversity of typologies across religions, cultures, and regions. Even a single worship space may require multi-functionality if used for a variety of service types or events. In addition to supporting the speech and/or music delivered as part of a service, the space must be supportive of congregant participation—ranging from lively exaltation to quiet reflection. The result is a richly complex and diverse set of acoustic approaches in the realm of worship space design. The new book, Worship Space Acoustics: 3 Decades of Design (Eds. Bradley, Ryherd, + Ronsse, Springer/ASA Press, 2016) provides a wide-ranging tour through churches, synagogues, mosques, and other worship spaces designed during the past 30 years. Acoustical consulting firms, architects, and worship space designers from across the world contributed their recent innovative works, including detailed renderings and architectural drawings, acoustic data graphs, and space descriptions. The content paints a picture of key worship space acoustic design goals and strategies from the last three decades. Case studies and overall themes from the book will be presented.
An example of dissociation between speech intelligibility and perceived reverberation
Authors: Zahorik Pavel , Ellis Gregory M.
Published: May 2016

It is well known that reverberation can affect the intelligibility of speech. Psychophysical and computational results have demonstrated that the relationship is inverse: an increase in the amount of reverberation results in a decrease in intelligibility. From the architectural acoustics literature, it is also well known that there is a direct relationship between the physical amount of reverberation and perceived reverberation. It therefore might be assumed that perceived reverberation and intelligibility are inversely related, although here a situation is demonstrated in which the two are effectively independent of one another. Using virtual auditory space techniques to simulate reverberant sound field listening, it is shown that when reverberant sound level is artificially decreased in the ipsilateral ear and naturally preserved in the contralateral ear, perceived reverberation is unaffected, but speech intelligibility is markedly improved. This dissociation likely results from the differential monaural and binaural aspects of reverberation, and is consistent with the idea that perceived reverberation is multidimensional. These results also suggest a potential binaural approach to the application of improving speech intelligibility in reverberation that does not limit the positive sound quality benefits of reverberation.