bluuebunny/crossref_metadata_2025 huggingface dataset:
Sensitivity analysis of the performance of a linear alternator at mechanical resonance under thermoacoustic power conversion conditions
Authors: Ibrahim A. H. , Yassin Ahmed , Abdel-Rahman Ehab
Published: May 2016

A linear alternator lie at the interface between the acoustic power generated by a thermoacoustic engine and an electric load, and thus, its performance is significantly controlled by its matching with the thermoacoustic engine and with the electric load. Under thermoacoustic power conversion conditions, small unavoidable changes in the operating conditions may incur significant effects on the alternator performance. In this work, the sensitivities of several alternator performance indices, namely, the acoustic-to-electric conversion efficiency, the mechanical stroke, and some of the main alternator losses (mechanical damping loss, seal loss, and electric copper loss), are examined to small changes in four operating conditions. Using the methodologies of the design of experiments and sensitivity analysis, a scheme of experiments is designed and carried-out to analyze the sensitivity of these indices to ± 10% changes in operating conditions at mechanical resonance. The operating conditions considered are the gas mixture composition, the mean gas pressure, the dynamic pressure ratio acting on the alternator and the electric load. The results reveal how variations in each of these operating variables as well as variations in their combined interactions affect the alternator’s performance with respect to the results obtained in a reference experiment.
Pitch, dynamics, and vowel tuning in choral voice: Utilizing resonance strategies to train stylistic variance for choral singers
Authors: Harris Jonathan D. , Mehaffey Laurel
Published: May 2016

Building off of the notion of absolute timbre and its influence on the perceptual and acoustical definition of vowel, we explore acoustic resonance strategies that can help singers address the challenges of performing in varied styles. Choral singers have to manage variation in singing styles more than any other musician, and yet, they are often the musicians with the least amount of formal training. Most choral directors choose a one-size-fits-all resonance strategy that accentuates the fundamental and suppresses other harmonics. This “Choral Cathedral” resonance strategy minimizes the challenges inherent in balancing voices whose power spectra vary, but eliminates many of the possibilities available to the voice. By training singers to recognize resonant strategies, and how they function and feel, singers can begin to explore more of their voice’s potential. Ultimately, this creates a more satisfying artistic experience for singer and audience alike. We use spectral analysis of different resonant strategies to show the impact of the absolute timbre of individual harmonics. We show how the vocal tract, even beyond the first and second formant, can create predictable acoustical environments unique to certain singing styles that singers can learn to achieve.
Deep learning for unsupervised feature extraction in audio signals: A pedagogical approach to understanding how hidden layers recreate, separate, and classify audio signals
Authors: Nykaza Edward T. , Boedihardjo Arnold P. , Wang Zhiguang , Oates Tim , Netchaev Anton , Bunkley Steven L. , Blevins Matthew G.
Published: May 2016

Deep learning is becoming ubiquitous; it is the underlying and driving force behind many technologies we use everyday (e.g., search engines, fraud detection warning systems, and social-media facial recognition algorithms). Over the past few years, there has been a steady increase in the number of audio and acoustics related applications of deep learning. But what is exactly going on under the hood? In this paper, we focus on deep learning algorithms for unsupervised feature learning. We take a pedagogical approach to understanding how the hidden layers recreate, separate, and classify audio signals. We begin with a simple pure tone dataset, and systematically increase the complexity of this dataset in both frequency and time. We end the presentation with some feature extraction examples from real-world environmental recordings, and find that these features are easier to interpret given the understanding developed from the simpler tone datasets. The unsupervised feature learning techniques explored in this paper include: restricted Boltzmann machines (RBMs) and auto-encoders (AEs).
Machine-learning models for the prediction of long-range outdoor sound propagation
Authors: Hart Carl R. , Wilson D. K. , Pettit Chris L. , Nykaza Edward T.
Published: May 2016

Long-range outdoor sound propagation is characterized by a large variance in sound pressure levels due to factors such as refractive gradients, turbulence, and topographic variations. While conventional numerical methods for long-range propagation address these phenomena, they are costly in computational memory and time. In contrast, machine-learning algorithms provide very fast predictions, which this study considers. Observations from either experimental data, or surrogate data from a numerical method, are required for the training of machine-learning models. In this study, a comprehensive training set for the machine learning was created from excess attenuation predictions made with a Crank-Nicholson parabolic equation (CNPE) model. Latin hypercube sampling of the parameter space (source frequency, meteorological factors, boundary conditions, and propagation geometries) generates a set of input for the CNPE model and machine-learning models. Consideration is given to ensemble decision trees, ensemble neural networks, and cluster-weighted models for nonlinear regression. The large variance in excess attenuation, from the CNPE model, presents a challenge for accurate machine-learning model predictions. For example, given 5000 samples the overall root-mean-square error for an ensemble decision tree model is 6.7 dB. Errors related to sample size, modeling approaches, and propagation ranges are quantified in this study.
Statistical analysis of multilayer porous absorbers with Bayesian inference
Authors: Fackler Cameron J. , Hurrell Alistair , Beaton Douglas , Xiang Ning
Published: May 2016

In noise control and other applications, porous sound-absorbing materials may be constructed of multiple layers of homogeneous materials. This work applies Bayesian inference to study and analyze such multilayer porous materials. The analysis utilizes a measurement of the overall material's acoustic surface impedance and a transfer-matrix porous material acoustic model. The number of layers present in the multilayer porous absorber under test and the physical properties of each layer are inversely determined. Bayesian model selection implements Occam's razor to determine the number of layers present in the sample, based on the measured impedance data and without any a priori knowledge of the number of layers. Once the number of layers has been determined, Bayesian parameter estimation inversely determines the physical properties of all layers simultaneously. A Markov chain Monte Carlo method, nested sampling, is applied to explore efficiently the high-dimensional parameter space inherent to this inverse problem. This sampling method automatically implements the model selection and parameter estimation components to analyze practical multilayer porous absorbers.
Dose-effect relationships for annoyance due to road traffic noise: Multi-level regression and consideration of noise sensitivity
Authors: Gille Laure-Anne , Marquis-Favre Catherine
Published: May 2016

An in situ survey was performed in eight French cities in 2012 to study the annoyance due to combined transportation noise sources. The European Union dose-effect relationships were compared to these new survey data for noise annoyance due to road traffic noise. The measured annoyance was not satisfactorily predicted by these curves: only the percentages of people highly annoyed by road traffic noise was well predicted. Following a multi-level regression as used to construct the European Union dose-effect relationships, new dose-effect relationships were proposed. These new dose-effect relationships enabled a better calculation of noise annoyance due to road traffic noise. Finally, a methodology to consider noise sensitivity in the computation and the percentage of people sensitive to noise in the results is proposed, as this non-acoustical factor is well known to influence noise annoyance. However, the results showed that taking into account such variable did not enable to enhance the dose-effect relationships.
Temporary unilateral hearing loss during development impairs behavioral and neural sensitivity to interaural level difference cues for sound localization
Authors: Anbuhl Kelsey L. , Greene Nathaniel T. , Brown Andrew D. , Benichoux Victor , Ferber Alexander T. , Tollin Daniel J.
Published: May 2016

Children who experience persistent conductive hearing loss (CHL) early in life often display binaural hearing impairments that persist long after CHL is resolved, suggesting abnormal central auditory development. Abnormal sensitivity to interaural level differences (ILDs) is particularly likely as a CHL (such as an ear infection) can attenuate sound in the affected ear by >30 dB, dramatically distorting ILD cues. Here, we quantified the effects of unilateral CHL on (1) behavioral spatial acuity and (2) neural information processing of ILD cues in the guinea pig auditory midbrain (inferior colliculus, IC) using the mathematical framework of Fisher information (FI). Animals raised with unilateral CHL displayed larger minimum audible angles for high-pass noise compared to age-matched controls, suggesting impaired ILD sensitivity. Based on acoustic directional transfer function measurements, ILD discrimination thresholds were elevated by ~3–6 dB. Following behavior, extracellular recordings were made in the IC contralateral to the previously occluded ear, and ILD discrimination thresholds for single neurons were determined using FI. Across the population, neural ILD discrimination was moderately impaired (~2–3 dB worse-than-control) in CHL animals. Impaired processing of ILD in the IC may in part explain the spatial discrimination deficits observed in animals and children with developmental CHL.
Bridging the chasm: Animal physiology and human psychophysics
Authors: Palmer Alan
Published: May 2016

A goal of animal auditory neuroscience is to understand how humans process and perceive sound. Encouragingly, hypotheses about brain function, generated from psychoacoustics, are sometimes confirmed by physiological experiments. A notable example is the Jeffress model of processing of interaural time differences. This has been largely supported by physiology and indeed we showed that neural activity in the midbrain and cortex, in response to Binaural Masking Level Difference stimuli, was entirely consistent with this cross-correlation model of binaural processing. However, such comparisons of physiology and psychophysics are often beset by caveats of species and anesthesia. This is one reason why the sharpness of human frequency tuning is still currently debated. In recent experiments, we have measured tuning behaviorally and by direct and indirect physiological methods, all in the same species. These different measures are in good agreement, supporting the notion that the cochlea determines perceptual frequency selectivity, and indirectly that perhaps frequency selectivity is different in humans. That notwithstanding, it seems clear that comparisons of animal physiology and human psychophysical measures provide important confirmations and insights into human auditory function.
Far field prediction of sound pressure level using panel contribution analysis and scale modeling
Authors: Herrin David W. , Cheng Gong
Published: May 2016

Panel contribution analysis is reviewed and then utilized to predict the sound radiation from a generator set. The generator set is divided into patches and transfer functions between the sound pressure at a point in the far field and the velocity of a patch were determined reciprocally both for the full-scale structure and a half-scale model. With the generator set running, a P-U probe was used to measure particle velocity and sound intensity simultaneously on each patch. The sound pressure level at a receiver point located 4.9 m away from the side of the generator set was calculated assuming uncorrelated and correlated sources. The predicted sound pressure, based on both full and half scale models, compared well with that measured. Transfer functions were also determined using boundary element methods and compared well with measurement. In addition, the contributions from each surface of the generator set enclosure were determined.
Ultrasonic imaging with wave mode adaptive weights and global matched coefficient
Authors: Sternini Simone , Nguyen Thompson V. , Lanza di Scalea Francesco
Published: May 2016

This paper discusses some improvements to ultrasonic synthetic imaging in solids. Specifically, the study proposes new adaptive weights applied to the beamforming array that are based on the physics of the propagating waves, specifically the displacement structure of the propagating longitudinal (L) mode and shear (S) mode that are naturally coexisting in a solid. The wave mode structures can be combined with the wave geometrical spreading to better filter the array and improve its focusing ability compared to static array weights. The paper also proposes compounding, or summing, images obtained from the different wave modes to further improve the array gain without increasing its physical aperture. The wave mode compounding can be performed either incoherently or coherently, in analogy with compounding multiple frequencies or multiple excitations. Furthermore, the introduction of a global matched coefficient computed through the matching of measured and expected times of flight will be presented to show additional improvements in the image reconstruction process. Numerical simulations and experimental testing demonstrate the potential improvements obtainable by the wave structure adaptive weights and the global matched coefficient compared to either static weights in conventional delay-and-sum focusing, or adaptive weights based on geometrical spreading alone in minimum-variance distortionless response focusing.
Preliminary study of extraterrestrial optical vibrometry for an impactor mission to Europa
Authors: Campbell Thomas , Brewer John , Okutsu Masataka , Turo Diego , Vignola Joseph
Published: May 2016

We present a methodology to determine the thickness and material properties of the icy crust of Europa, a satellite of Jupiter. Instruments proposed for NASA’s Europa Multiple Flyby mission may be insufficient to adequately measure the ice’s thickness. We propose a complementary experiment in which vibration of the Europan surface is induced by an artificial impact. Optical vibrometry techniques, such as 2-D digital image correlation and vibration magnification are considered for detecting the displacement field at a sub-pixel level. We make use of COMSOL Multiphysics, which simulates wave motions via the finite element method. Dispersion curves of elastic waves and the wavenumber filtering are used to estimate the thickness and properties of the extraterrestrial ice.
Listener profiles for dysarthric and accented speech
Authors: Neel Amy T.
Published: May 2016

In order to determine which aspects of speech contribute most to speech intelligibility, listeners rated several speech features for sentences produced by speakers with dysarthria and for passages read aloud by speakers of English as a second language. For the dysarthric speech, speech components included rate, stress, intonation, articulation, voice quality, and nasality in addition to speech intelligibility. For the accented English passages, the speech components were rate, stress, intonation, articulation, and other aspects of speech as well as overall intelligibility, accentedness, and language competence. For both types of speech, articulation was the best predictor of intelligibility ratings. Voice quality, rate, and nasality made minor contributions to intelligibility ratings for dysarthric speech. Rate also contributed slightly to intelligibility ratings for the accented English passages. Potential differences in the salience of speech components for listeners will be discussed. Use of the perceptual profile approach for planning treatment and assessing treatment efficacy for dysarthric and accented speech will also be addressed.
Auditory and cognitive aging: Differences between speech intelligibility and speech-in-speech intelligibility
Authors: Pichora-Fuller Margaret K.
Published: May 2016

Older adults, even those with normal or near-normal audiograms, report greater subjective listening difficulty in everyday life compared to younger adults. However, their difficulties are not well predicted from pure-tone or speech audiometry in quiet or noise. Speech intelligibility tests based on word recognition do not incorporate many of the sensory and cognitive challenges that listeners confront in everyday situations where it is necessary to understand a target talker when there are competing talkers in the auditory scene. Speech-in-speech intelligibility is affected by age-related differences in auditory and cognitive processing. Age-related differences in auditory temporal processing reduce access to periodicity and temporal envelope cues that serve stream segregation and spatial listening. Age-related differences in cognitive processing are reflected in difficulty remembering speech heard in multi-talker babble or switching spatial attention when there is uncertainty about the location of a target talker in a multi-talker display. Furthermore, when listening occurs in multi-tasking conditions (e.g., listening while walking), there are increased and competing demands for cognitive resources that may affect performance on listening and/or the competing tasks. These examples highlight the importance of both inter- and intra-individual differences in speech-in-speech intelligibility that depend on the interaction of auditory and cognitive processing abilities.
Multiple snapshot and multiple frequency compressive matched field processing
Authors: Gemba Kay L. , Hodgkiss William S. , Gerstoft Peter
Published: May 2016

Matched field processing is a generalized beamforming method which matches received array data to a dictionary of replica vectors to locate and track a source. Its solution set generally is sparse since there are considerably fewer sources than replicas. The problem is also underdetermined since the number of sensors are less than the number of unique depth-range cells. Using compressive sensing (CS), the traditional spatial matched-filter problem is reformulated as a convex optimization problem subject to a row-sparsity constraint (RSC). The RSC selects the best match among the replica dictionary when using multiple snapshots. It is found that CS performance is equivalent to the Bartlett processor when comparing the sparse solution to the ambiguity surface’s peak for any number of snapshots in a single frequency—single source scenario. Results also indicate that CS performs similarly to the adaptive white noise constraint processor in a multiple source scenario. The RSC can further be exploited to select a common depth-range cell from snapshots corresponding to multiple frequencies to improve the source tracking in the presence of data-replica mismatch. Results are demonstrated using both simulated and SWellEx-96 experiment data.
Acoustic beamfolding: New potentials enabled by interfacing reconfigurable origami and acoustic structures
Authors: Lynd Danielle T. , Harne Ryan L.
Published: May 2016

Acoustic transducer arrays yield large spatial and spectral change in energy transmission through strategic positioning of planar array elements. Yet, unless array elements are actively tuned through phase delay controls, the array performance characteristics remain fixed and suitable for limited purposes. Origami, the art of paper folding, is a means to introduce enormous topological change through simple, kinematic translation and rotation of connected, planar facets, which is one reason for its growing attention as a fluent vehicle to remarkably adapt system properties for multifunctional purposes. In this research, we integrate acoustic transducer array development and origami design principles to establish a new framework for adaptive acoustic energy shaping effected by simple geometric and kinematic folding relations. From a flat-folded strip to an unfolded plane, our theoretical and experimental results show that this transducer design concept leads to powerful means to tune the significance of radiated acoustic energy across orders of magnitude and to easily tailor the acoustic power transmission to the far field.
Objective metrics, subjective descriptors, and their elasticity in the face of experience
Authors: Sacks Jonah
Published: May 2016

Acousticians have long associated certain objective metrics with subjective aural qualities: C80 with clarity, for example. But the subjective quality of sonic clarity is complex and nuanced, and the descriptor means different things to different people. C80 describes the strength of early reflections relative to overall reflected sound energy. But these reflections may either help or hinder perceived musical clarity in different halls, different conditions of use, and to different listeners. New research, listening experience, and developments in room acoustics design challenge us to update our understanding and use both of subjective aural qualities and descriptors (such as clarity), and of objective metrics (such as C80). This talk will cite research (Lokki et al., Griesinger, etc.), project examples, and the author's own listening observations.
Multimodal perception in concert halls: Where do we look when we listen?
Authors: Minors Anne L.
Published: May 2016

Concert hall design is at a crossroads between its origins, which have been unamplified orchestral music and singing, and the forces of popular music, which depend mostly on amplified sound and multimedia accompaniment. Concurrently, there has been a revolution in the way that the buildings are designed in the last 25 years. Computer modeling techniques enable architects and engineers to conceive and build complex geometrical forms and acoustic engineers to analyze future building interiors to promote a rich sound experience. However, despite a concert being a multisensory experience, relatively little work has been done on investigating how the visual aspects of the concert hall may impact on the acoustical experience. This paper investigates multisensory perception in different concert halls by examining where people look when actively listening to music and whether this affects how they perceive the experience.
MRI-targeted delivery of brain-penetrating non-viral gene nanoparticles across the blood–brain barrier with focused ultrasound: Neurodegenerative disease application
Authors: Price Richard J.
Published: May 2016

The delivery of systemically administered nanoparticles to the brain is impeded by both the blood–brain barrier (BBB) and the nanoporous electrostatically charged extracellular matrix. However, we have previously shown that these barriers may be overcome by opening the BBB with MRI-guided focused ultrasound (FUS) and microbubbles (MBs) and engineering the nanoparticles to have “brain penetrating” properties via the addition of a dense PEG corona. Here, we first delivered non-viral reporter gene-bearing brain-penetrating nanoparticles (BPN) to rat brain using FUS and MBs, resulting in robust dose-dependent gene expression in the FUS-targeted region through day 28 and a transfection efficiency >40%. Neurons and astrocytes were transfected equally, and neither toxicity nor gliosis were evident. We then tested whether the approach had therapeutic potential for treating Parkinson’s disease by delivering neurotrophic (GDNF) gene BPN to the striatum of 6-OHDA treated (i.e., Parkinson’s) rats. For GDNF BPN treated 6-OHDA rats, motor impairment tests (apomorphine-induced rotation and cylinder) revealed significant improvement and dopaminergic neuron density was fully restored in both striatum and substantia nigra pars compacta. We conclude that MRI-guided BPN delivery with FUS and MBs is a safe and effective strategy for brain transfection that has potential as a non-invasive treatment for Parkinson’s neurodegeneration.
Explaining microphones and loudspeakers in a musical acoustics course for non-scientists
Authors: Maher Robert C.
Published: May 2016

Contemporary courses in the field of musical acoustics rely upon basic audio engineering components such as acoustical transducers: microphones, accelerometers, and loudspeakers. Most students are very aware of the practical use and behavior of such devices, but they seldom have a useful understanding of the physical and engineering principles behind the design of these essential components. This paper presents a lesson example explaining microphones and loudspeakers for a general-interest undergraduate college course entitled “The Science of Sound.” The lesson includes a descriptive lecture component, examples and discussion, and a hands-on demonstration.
Electroacoustics laboratory assignments for computer music students
Authors: Berdahl Edgar , Beck Stephen D.
Published: May 2016

A series of pedagogical exercises are described that integrate concepts from traditional musical acoustics laboratory assignments with the fundamentals of computer music. Students are asked to rapidly prototype hybrid devices that contain both musical acoustic components as well as sensors, embedded audio signal processing, and loudspeaker drivers. To help students rapidly complete working prototypes, students are provided with working audio effects and sound synthesizer programs. Students learn the programming language (Pure Data) only by example for making small changes to the previously designed programs, as they are integrated with custom-made, physical acoustics components (e.g., D-I-Y vibrating strings, drums, columns of air, rattles, etc.). Music students first learned that building quality acoustic instrument components is harder than they originally thought. Although out-of-the-box thinking is regarded as an important factor in devising novel electroacoustic prototypes, students starting from previously existing designs and making small changes tended to be more successful (at least initially) than students striking out on completely new paths. Several pictures of completed instruments will be shown, and one or two example prototypes of electroacoustic instruments and electroacoustic audio effects will be presented live. The example “starter“ programs in Pure Data will be made available for community members wishing to run them on the Raspberry Pi 2, as supported by the author's Satellite CCRMA platform.
Comparison of surface wind noise predictions from mirror flow and rapid-distortion models of atmospheric turbulence
Authors: Lyons Gregory W. , Yu Jiao , Raspet Richard
Published: May 2016

For atmospheric acoustic measurements at the ground surface, the principal source of the intrinsic wind noise is shearing of the turbulence by the mean flow. The pressure spectra from this turbulence-shear mechanism depend on two-point statistics of the anisotropic, inhomogeneous atmospheric turbulence. The inhomogeneity of the surface-normal velocity component can be realistically modeled by the mirror flow, which is a superposition of two correlated isotropic turbulent fields in transformed coordinates. Another analytical framework is rapid-distortion theory, which approximates the turbulence as the result of linearized distortion of an initially homogeneous field by the mean flow. This study compares turbulence-shear spectra calculated with the mirror flow model and rapid-distortion models for both surface blocking effects and mean shear distortion. For each case, the model parameters are estimated by fits to the single-point velocity spectra recorded in a recent experiment near Laramie, Wyoming. The subsequent model predictions for the wind noise spectra are compared with simultaneous measurements from flush-mounted infrasound sensors. [Work supported by the U.S. Army Research Laboratory (Grant No. W911NF-13-2-0021) and the National Natural Science Foundation of China (Grant No. 11304137).]
Calculation of sound radiation in infinite domain using a meshless method
Authors: Wu Shaowei , Xiang Yang
Published: May 2016

A meshless method coupling with a variable order infinite acoustic wave envelope element for sound radiation calculation in infinite domain is presented with the aim of accurately calculating the acoustic radiation and improving computational efficiency. It is based on using the element-free Galerkin method in the inner region enclosing the radiator and a variable order infinite acoustic wave envelope element in the outer region for the proper modeling of the pressure amplitude decay. The details are provided for the derivation and implementation of this method. The factors of influencing the performance of the method, which include the shape function constructing, the number of integration points, the weight functions, and the support domain, are discussed. A hybrid adaptive Gauss-Legendre quadrature is devised to obtain good integration accuracy. The suitable radius of the support domain for the acoustic field calculation in free space is also determined by use of numerical experiments. A complex structure is designed for simulation to validate the method. The results illustrate the accuracy, applicability, and effectiveness of this method.
Oceanographic constraints on seafloor surveys of the New England continental shelf
Authors: de Moustier Christian
Published: May 2016

In July 2015, a seafloor survey of a 30 km x 10 km area of the New England continental shelf, centered at about 40.4750 N, 70.6030 W with an average depth of 74 m, highlighted constraints imposed by the locally dynamic oceanography. Variability in time and space of the water column in the survey area was observed in CTD casts, in underway temperature and salinity data, and in pervasive refraction correction errors symptomatic of internal waves. Depth profiles of temperature and practical salinity show evidence of sporadic continental slope water intrusion on the shelf between 50 m below sea level and the bottom. Underway data reveal a front responsible for an abrupt 10-m/s drop in sound speed along track at 5-m depth. Short of restricting soundings to ±300 about nadir, there is no mitigation for seafloor surveying through internal waves because frequent sampling of the sound-speed profile along track, e.g., with an underway sound-speed profiling system, provides no information on the water masses on either side of the track, which if different due to internal waves cause refraction correction errors because the assumption of a local horizontally stratified water column is violated. [Work funded by ONR-32OA.]
Geoacoustic inference and the search for ground truth
Authors: Holland Charles W. , Dettmer Jan , Dosso Stan D.
Published: May 2016

A variety of commercial, military, and scientific applications require knowledge of seabed properties. In the ocean acoustics community, the properties typically of interest are sound speed, density, and attenuation and sometimes shear speed and attenuation. Numerous approaches have been developed to estimate these by geoacoustic inference, i.e., by measuring a quantity (e.g., reflection coefficient, transmission loss, or pressure across a hydrophone array) and estimating the seabed properties from the data. Inference requires a large number of assumptions on the depth, range, and frequency dependencies of ocean and seabed properties. These assumptions are widely, and often necessarily, made with minimal supporting information. In cases where the actual physical seabed properties are of interest there is an important requirement to validate the result. Measurements on sediment cores are widely called “ground truth.“ However, these data frequently contain bias errors and exhibit rather large uncertainties, sometimes larger than those from geoacoustic inference. Here, difficulties and opportunities associated with collecting, conducting, and interpreting measurements on cores are discussed. Cores can be a useful independent measurement of sediment properties, but should not be termed as “ground truth.“ [Work supported by the Office of Naval Research and the Centre for Maritime Research and Experimentation.]
Comparisons between room acoustics preferences of musicians and non-musicians regarding solo-instrument and orchestral motifs in auralizations
Authors: Lawless Martin S. , Vigeant Michelle C.
Published: May 2016

Musicians are good candidates for room acoustics subjective testing since they regularly practice critical listening skills, but recent work suggests that non-musicians should also be included as the two groups may have diverse room acoustics preferences. A study was conducted to evaluate these two participant groups to ensure the representation of the entire population in room acoustics studies. The specific goal of the present work was to investigate preference differences between musicians and non-musicians in the evaluation of musical stimuli with varying reverberation time (RT). Preliminary data introduced at a prior meeting demonstrated that on average musicians and non-musicians displayed similar preference trends for auralizations of two solo-instrument motifs. However, a k-means clustering analysis revealed that a greater percentage of non-musicians exhibited statistically indistinct preference ratings across the stimuli, denoted as the “no preference” group. This result may indicate that non-musicians are not good candidates for room acoustics testing. The present study expands upon the preliminary work with additional participants that assessed both the solo-instrument motifs and two new orchestral motifs simulated in a concert hall with RT ranging from 0.0 to 7.2 s. The preference trends were also compared to the types of musicians tested.
Acoustically controlled ultrasound-mediated drug delivery to the central nervous system
Authors: O'Reilly Meaghan A. , Jones Ryan M. , Hough Olivia , Hynynen Kullervo
Published: May 2016

The barriers of the central nervous system (CNS), including the blood-brain barrier (BBB) and blood-spinal cord barrier ((BSCB), prevent most drugs from reaching therapeutically significant concentrations in these tissues. Thus, the BBB and BSCB are significant obstacles in the treatment of CNS disorders. When combined with microbubbles, ultrasound can be used to transiently open these barriers to facilitate the delivery of drug, gene and cell therapies. There exists a regime of microbubble excitation where a completely reversible opening effect can be achieved without damaging the tissue. We, and others, have previously presented methods to control the acoustic exposures during treatment to target this regime, and thus ensure efficacy and safety. This talk will present recent work in ultrasound-mediated drug delivery to the CNS. New findings of the role of microbubble emissions in controlling these exposures will be discussed, including dose-dependency and the temporal characteristics of stable cavitation signatures.
Neuroprotection and neurorestoration through the opened blood-brain barrier using focused ultrasound and microbubbles
Authors: Konofagou Elisa
Published: May 2016

After cancer and heart disease, neurodegenerative diseases, such as Alzheimer's, Parkinson's, multiple sclerosis (MS) and amyotrophic lateral sclerosis (ALS), take more lives each year than any other illness. Although some effective treatments are available, most of those diseases remain undertreated. The blood-brain barrier (BBB) has been proclaimed as the “bottleneck“ of brain drug delivery. Focused ultrasound (FUS) in conjunction with microbubbles is currently the only technique that can open the BBB locally, transiently, and noninvasively. Our group has demonstrated that pharmacological compounds of variable sizes can not only traverse the BBB but also induce therapeutic effects in the presence of neurodegenerative disease. In this paper, the trans-BBB neurotherapeutic delivery with FUS is shown to (1) be safely facilitated within a specific pressure range in both mice and non-human primates through the mechanism of cavitation, (2) be controlled through the pressure amplitude and microbubble characteristics, (3) induce downstream signaling effects in the neuronal cell, (4) trigger neuroprotection and neurorestoration relevant in the treatment of neurodegeneration, (5) be localized and monitored in real time through cavitation monitoring and mapping. BBB opening is combined with systemic administration of neurotrophic molecules or adeno-associated viruses that allow for neuronal protection and growth in the BBB-opened regions.
Detailed measurements on lingual organ pipes for developing innovative methods and software for the pipe design
Authors: Angster Judit , Rucz Peter , Miklos Andras
Published: May 2016

Within the framework of a European research project exciting new results have been achieved recently in the research of lingual organ pipes. The main objectives of the project are to solve practical problems of the dimensioning of reed organ pipes, to develop innovative methods and software for helping the sound design work of organ builder enterprises. A better understanding of the role of the shallot and resonator on the attack and the timbre of reed pipes is necessary for this reason. Visualization of reed motion by high speed camera and measurements of reed velocity, wind pressure in the boot and shallot, and sound pressure in the shallot and at the end of the resonator have revealed interesting details about the very complex process of sound generation of lingual organ pipes. These experiments have been carried out in close cooperation with the participating organ builder firms. As examples, a few results of the measurements of Crumhorn and Vox Humana pipes are presented. These results, combined with computer simulations of resonators, can be used for optimizing shallots and resonators. Moreover, the extended knowledge of sound generation can serve as a physical model of sound synthesis.
The voice acoustics of the 2016 United States presidential election candidates: A cross-gender study
Authors: Signorello Rosario , Rhee Nari
Published: May 2016

The present study investigates the acoustic voice profiles (vocal fundamental frequency and intensity) of two female (Hillary Clinton and Carly Fiorina) and two male (Bernie Sanders and Donald Trump) candidates to the 2016 United States presidential election. The criteria used for choosing the speakers were based on: (a) an online survey we conducted in 2015; (b) the prediction markets’ statistics; (c) the number of endorsements from party elites; (d) the Iowa and the New Hampshire polls; (e) the amount of money raised by the candidate; and (f) the candidates’ gender from both Democratic and Republican parties. Voice stimuli for each of these speakers were collected for three different communication contexts: a political campaign monologue; a political peers-addressed speech; and non-political interview. Results confirm and expand previous findings [JASA 136(4), 2295] showing cross-cultural and gender similarities in voice acoustics supporting the hypothesis of several ongoing cross-cultural/gender processes of integration among some innate and cultural/linguistic vocal habits to convey leadership status: leaders estimate audience’s biological and social traits, manipulate vocal ranges of F0 and SPL accordingly, while maintaining women’s and men’s particular acoustic average features of F0 and SPL significantly different. [Supported by NIH grant DC01797.]
Parametric design applications in architectural acoustics—Generation and optimization of reflective surfaces for specific source/receiver combinations
Authors: Mayell Marcus R. , Hoffman Ian B.
Published: May 2016

This investigation considers the potentials of what are normatively visual parametric design tools, within acoustics design thinking. The typical workflow inherent to most room acoustic software consists of architectural design followed by analysis. In response to the emergence of parametric tools in architectural design, like Rhino and Grasshopper, acoustic designers now have the potential to carry out some analysis through visualization in a more streamlined manner. Furthermore, parametric tools carry the capability to alter the typical workflow from “design followed by analysis” to a more integrated design and analysis workflow, or in some cases even a set criteria followed by a set of design solutions. Through investigation and application of these idea as a part of a recent Master of Architecture thesis project at Judson University, I have been able to develop and test specific parametric definitions which define and visualize reflecting surface potentials based on set source and receiver area criteria.
Measuring perceptual effects of infrasound
Authors: Nelson Peggy B. , Sullivan Michael , Adams Meredith , Lueker Matthew , Marr Jeffrey , Thigpen Bruce
Published: May 2016

A multi-disciplinary group of researchers at the University of Minnesota Center for Applied and Translational Sensory Science (catss.umn.edu) are designing and pilot testing the perceptual effects of infrasound, in collaboration with Eminent Technologies (rotarywoofer.com). An infrasound generator simulates the acoustic signature of audible sound and infrasound generated by wind turbines in the field. With the support of Xcel Energy, the team of engineers, otologists, hearing scientists, and balance experts are evaluating the effects of infrasound only, acoustic turbine sound, and combined infrasound and acoustic sound. We are testing listeners’ quiet detection, masked detection, discrimination, and rating of signals. Pilot results will be described. Together we hope to test the range of perceptual responses to turbine-generated infrasound and audible sound. [Work supported by Xcel Energy RD4-12 to Jeffrey Marr, St. Anthony Falls Laboratory.]
Acoustic harmonic generation and phase conjugation with a single layer of bubbles
Authors: Lombard Olivier , Barriere Christophe , Leroy Valentin
Published: May 2016

Bubbles are well known for being strong nonlinear scatterers in acoustics. This feature is actually used in medical ultrasound, and nonlinear phenomena, such as phase conjugation [1] or second-harmonic generation [2], had been reported in bubbly liquids. We carried out experiments and calculations on a particularly simple bubbly medium: a single layer of bubbles trapped in a yield-stress fluid. We show the existence of an ideal bubble concentration that maximizes the nonlinear second harmonic generation by the layer. It results from the interplay between the nonlinear response and the strong multiple scattering in the system [3]. The same nonlinear mechanism can be used to obtain phase conjugation, with a probe wave at frequency f, and pump wave at 2f. The single layer of bubbles is then a sub-wavelength phase conjugation mirror. We studied its efficiency in terms of direction and magnitude of the reflected wave. [1] D. V. Vlasov et al., Sov. Phys. Acoust. 29 (1983). [2] J. Wu, Z. Zhu, J. Acoust. Soc. Am 89 (6) (1991) [3] O. Lombard et al., EPL, 112 (2015).
Neural activation patterns indicate robust auditory nerve synchrony generated with octave-band chirps
Authors: Thompson Ivy , Earl Brian
Published: May 2016

Recent research has suggested that the amplitude of high-intensity compound action potentials (CAPs) can detect auditory nerve damage that is missed by traditional threshold measurements. The use of octave-band chirps may enhance neural synchrony and provide clinicians and researchers a precise tool for identifying changes in auditory nerve integrity. A group of Mongolian gerbils (N = 12) was used to compare the difference in amplitude-intensity functions and neural activation patterns generated by octave-band chirps and tonebursts at octave frequencies between 2 and 16 kHz at 40, 60, and 80 dB SPL. Amplitude-intensity functions revealed larger absolute CAP amplitudes for octave-band chirps than for tonebursts. Neural activation patterns were constructed by plotting the derivative of CAP amplitude across multiple conditions of simultaneous broadband noise that was high passed in 1/3 octave intervals. Neural activation patterns for octave-band chirps and tonebursts showed that the frequency location of peak activation was generally equivalent while the height of peak activation was greater for octave-band chirps than for tonebursts. This suggests that octave-band chirps elicit more synchronous neural firing, thereby indicating that they could be an optimal stimulus for detecting regional damage in auditory neurons that encode supra-threshold stimuli.
Comparison of Blackman, linear rise-fall, and linear rise-fall chirp signals in backward masking
Authors: Sears Robert , Smith Silas , Yonovitz Al
Published: May 2016

Backward masking is finding applications in clinical testing and the diagnosis of auditory processing disorders. Masking of a tonal signal by a band-limited noise in a backward masking paradigm requires significant vigilance and produces fatigue. This study compared the backward masking functions of ten normal hearing young (18–30 years) subjects using tonal stimuli with different signatures in order to provide a better contrast to the noise masker. Subjects adaptively tracked the tonal threshold using 2 dB changes. The noise stimulus was 70 dB HL, and the inter-stimulus interval (ISI) varied from 2 ms to 64 ms. The results will be described in terms of fatigue, tracking efficiency, and latency.
Backward masking of vowel-consonant stimuli
Authors: Cope Allie , Foster Kendra , Sears Robert , Smith Silas , Yonovitz Al
Published: May 2016

Backward masking (BM) has shown differential effects with age and auditory processing. BM may be related to reduced speech discrimination. Ten normal hearing subjects (18–30 years) were subjects in this study. This study utilized 21 VC stimuli followed by a white noise masker. The ISI interval was 5 ms, and the noise duration was 50, 100, and 200 ms. Each stimulus was randomly presented ten times. Confusion matrices determined consonant intelligibility and information transmission for distinctive features. Thus, the study investigated the accuracy of perception for English consonants as well as determined which of the distinctive features (voicing, nasality, continuancy, sibilancy, frontness, sonorancy, and labiality) remained preserved or changed when exposed to backward masking listening conditions. The results indicated a reduction in these selected features as well as reduced consonant identification as BM became more effective.
Identification of attended speech stream using single-trial electroencephalography recording
Authors: Somarowthu Ala , Ding Nai , Kong Ying-Yee
Published: May 2016

Selective attention differentially modulates neural responses to simultaneously presented speech streams. In this study, single-trial EEG classification was performed to identify the attended speech from a two-talker speech mixture. During EEG recordings, normal-hearing listeners paid attention to one speech stream while listening to speech mixtures. The target-to-masker ratios (TMRs) varied from −9 to + 9 dB. Individual speech streams were processed with head-related transfer functions to simulate different spatial locations. Two simulated spatial conditions (0 vs. + /−90 and + 45 vs. −45 degree azimuth) were tested for each TMR. Features related to (1) cross-correlation values between EEG signals and temporal envelope of each speech stream, or (2) correlation values between reconstructed speech from the EEG signals with the acoustic stimuli, were fed to the classifiers. The dimensionality of the feature vector was reduced using Principal Component Analysis. Linear Discriminant Analysis and Support Vector Machine were used to classify the EEG signals. Classifiers were trained and tested with a five-fold cross validation method on data pooled across TMRs and source locations for trial lengths from 50 s to 10 s. Average classification accuracy was 85% with a 50 s trial length and maintained high at 70% with a reduced trial length of 10 s.