bluuebunny/crossref_metadata_2025 huggingface dataset:
The duplex theory re-revisited: Spectral weighting of localization cues in tones and noises
Authors: Stecker G. Christopher , Folkerts Monica L. , Stecker Julie M.
Published: April 2019

It is widely suspected that sound localization is accomplished primarily through the use of low-frequency interaural-time-difference (ITD) cues and only secondarily via high-frequency ITD and level-difference (ILD) cues [Rayleigh, Philos. Mag. 13, 214–232 (1907); Wightman and Kistler, JASA 91, 1648-1661 (1992); Macpherson and Middlebrooks JASA 111, 2219–2236 (2002)]. Contemporary studies of cross-frequency interactions in spatial hearing have provided support for this view but have not directly identified the frequencies involved nor quantified the relative weighting of binaural cues weighting across components of a single complex. This study adapted the temporal-weighting approach of Stecker and Hafter [JASA 112, 1046–1057 (2002)] to measure spectral weighting functions (SWF) for (a) free-field and reverberant sound localization and (b) lateralization based on ITD and/or ILD. Across a wide range of conditions, SWFs featured enhanced weights for components in the vicinity of 400-800 Hz, supporting a narrow “dominance region” for localization and lateralization of complex sounds [Bilsen and Raatgever, Acoustica 28, 131–132 (1973)], and a precipitous drop in weights between 800 and 1400 Hz [Brughera et al., JASA 133, 2839–2855 (2013)]. [Work supported by NIH R01-DC016643.]
Consequences of interaural decorrelation of speech temporal fine structure
Authors: Baltzell Lucas , Best Virginia , Swaminathan Jayaganesh
Published: April 2019

The ability to understand a target speech signal against a background of interfering speech signals is typically improved when the interfering signals are spatially separated (spatial release from masking; SRM). Swaminathan et al. (2016) found a significant reduction in SRM when the temporal fine structure (TFS) across the left and right ears was decorrelated, suggesting that binaural TFS provides important cues that support SRM. One interpretation is that degrading binaural TFS prevents the extraction of reliable interaural time differences (ITDs), which in turn leads to a reduction in SRM. We tested this hypothesis by systematically decorrelating the binaural TFS, and measuring the effects on both ITD discrimination for speech stimuli and SRM in normal hearing listeners. We show that decorrelation leads to a systematic increase in ITD discrimination thresholds, as well as a systematic decrease in SRM. This supports the idea that binaural TFS is needed to access ITD information in speech, which is in turn required for SRM. Additionally, the relationship between these two tasks provides a framework for determining the extent to which reduced SRM in listeners with hearing loss can be attributed to reduced sensitivity to binaural TFS.
The effect of simulated Doppler frequency changes on detectability of complex tones
Authors: Feth Lawrence L. , Hoglund Evelyn M. , Dixit Omkar , Davis Matthew
Published: April 2019

The detectability of frequency changes designed to simulate the Doppler effect for moving sound sources has been well documented in the literature (Chowning, 1977; Ericson, 2001; Kaczmarek, 2005, Getzmann, 2008, and Pörschmann & Störig, 2009). The current study was designed to determine whether the presence of Doppler frequency shifts have a measurable effect on the detectability of complex sounds. Detection thresholds for single sinusoids with frequency changes ranging from the frequency DL to a full octave are compared with those for complex tones with selected components frequency modulated to simulate Doppler effects. A one-interval, adaptive tracking paradigm using the SIAM procedure (Kaernbach, 1991) was used to determine three points on the psychometric functions so that detection thresholds and slopes could be compared. For single component signals, the direction of frequency change and the span of the frequency sweep appear to have an effect on detectability. Results for complex tones require further explanation. [Work supported by a contract from CDO Technologies, Dayton, OH.]
Auditory detection and sound source elevation
Authors: Pastore M. Torben , Yost William
Published: April 2019

The spectral profile of a given sound stimulus varies with the spatial location according to the head-related transfer functions (HRTF) at both ears. For narrowband and tonal stimuli at frequencies above approximately 4 kHz, perceived sound source elevation has been shown to depend mainly on stimulus frequency instead of sound source location (e.g., Blauert, Morimoto), and this result has in turn been shown to correlate with spectral features of the HRTF (e.g., Middlebrooks). However, even though the HRTF is important to perceived elevation, listeners do not generally report a perceptual awareness of the spectral filtering that occurs as a result of the HRTF, suggesting that some form of spectral equalization may occur at some level beyond peripheral auditory processing. Therefore, depending on the level at which detection processing occurs, we might expect different detection thresholds for high frequency stimuli presented from different elevations, or, conversely, we might expect them to be the same. We will report data, collected in a soundfield, concerning the interaction, if any, of sound source elevation and auditory masked detection of high frequency stimuli.
Updating of spatial selective auditory attention under-compensates for listener head movement
Authors: Macpherson Ewan A. , Jeon Miyoung , Ransom Serena
Published: April 2019

Listeners can use spatial selective auditory attention (SSAA) to focus on one talker in a complex acoustic scene. In our dynamic SSAA task, listeners oscillate their heads ~±40 deg at ~0.5 Hz while five different simultaneous sequences of four spoken digits are presented from loudspeakers at 0 deg azimuth (the target) and ±22.5 deg and ±45 deg azimuth (four distractors); listeners report the target sequence heard. We have observed [ASA, Minneapolis 2018] that listeners are more likely to misreport distractors that are centrally located in head-centered coordinates at the moment of presentation, and that under static conditions, performance declines with increasing target eccentricity—suggesting either that listeners cannot rapidly update the focus of their SSAA to compensate head motion (“lag” ) or that they have difficulty directing SSAA eccentrically (“low gain” ). To differentiate these alternatives, spatio-temporal maps of SSAA, conditioned on head orientation and direction of motion during each digit, were derived by computing the percentage of reported digits corresponding to those emitted by each loudspeaker. The spatial pattern of errors depended primarily on head orientation and not on direction of motion, suggesting that in this task SSAA tends to remain centrally focused in head-centered coordinates (low gain) rather than lagging dynamic head position.
Passive Non-Reciprocity in Asymmetrical, Hierarchical, Nonlinear Metamaterials
Authors: Leamy Michael J. , Darabi Amir , Fang Lezheng , Fronk Matthew , Vakakis Alex
Published: April 2019

Reciprocity is a property of linear, time-invariant systems whereby the energy transmission from a source to a receiver is unchanged after exchanging the positions of the source and receiver. Non-reciprocity, on the other hand, violates this property and can be introduced to systems if time-reversal symmetry and/or parity symmetry is lost, or by introducing nonlinearity. While many studies have induced non-reciprocity by active means, considerably less attention has been given to acoustical structures that passively break reciprocity. In this talk, we will discuss passive, strongly nonlinear periodic structures which exhibit giant reciprocity breaking under impulsive and/or harmonic excitation. Numerical means are employed to generate dispersion curves, as a function of wave energy, which differ for left-to-right from right-to-left propagation. These dispersion curves become reciprocal at the limiting cases of low and high energy, which can be shown analytically. In between, varying degrees of non-reciprocity can be achieved, and in some regimes, giant reciprocity breaking is achieved with very little harmonic distortion. This suggests many possibilities for passive, non-reciprocal devices that operate with near-linear behavior.
Contrast parameter characterizes Bragg frequency gap in periodic flexural beams
Authors: Gallot Thomas , Pelat Adrien , Gautier Francois
Published: April 2019

Periodic structures exhibit frequency bands where destructive interferences prohibit wave propagation. Such behavior can be useful to mitigate vibrations, in particular when structure lightening is important. Band gap properties can be deduced from Bloch's theory approach, Plane Wave Expansion or Multiple Scattering methods. These methods require a full description of the unit cell geometry and its mechanical properties. In this work we focus on an ideal unit cell geometry to highlight the role of a contrast parameter in the band gap opening process. We consider flexural waves in beams and demonstrate analytically that the contrast parameter fully controls the first Bragg band gap. Numerical simulation and experiments on a beam demonstrator proves that the gap bandwidth is independent of the section geometry: only the flexural rigidity is involved. We propose a semi-analytic model for the central frequency gap that depends on the mass distribution. The established algebraic expressions for the band gap bandwidth and central frequency successfully matches the results in the practical case and can be used to design flexural wave cut-band filters. Finally, symmetry considerations explains the experimental observation of a second band gap, also suitable for vibration mitigation, due to coupling of flexural and compressional waves.
The benefit of acoustic beamforming in solving the “cocktail party problem” for persons with acquired aphasia
Authors: Villard Sarah , Mason Christine , Kidd Gerald
Published: April 2019

Acoustic beamforming has been shown to improve identification of target speech in noisy listening environments for individuals with sensorineural hearing loss. This study examined whether beamforming would provide a similar benefit for individuals with aphasia (an acquired neurological language deficit). Persons with aphasia (PWA) are known to exhibit impaired language comprehension abilities; however, most work on language comprehension in PWA has been conducted in quiet settings, and little is known about the impact of competing auditory information on performance. In this study, we measured the intelligibility of target speech masked by other speech or noise for two presentation/microphone conditions: one condition, designated “KEMAR,” provided natural spatial cues via KEMAR impulse responses; the second condition, designated “BEAM,” enhanced the target speech level via a single-channel beamformer. In each condition, subjects heard a target sentence at 0 deg azimuth concurrent with two independent maskers—speech or speech-shaped speech-envelope-modulated noise—from ±60 deg. Threshold target-to-masker ratios were measured adaptively for each subject, with individually-determined modifications in the procedures made for the subjects. Results indicated substantially lower (better) thresholds for the beamformer condition than for KEMAR, providing preliminary evidence that PWA may benefit from the use of acoustic beamforming in complex, multiple-source listening situations.
Automatic environmental soundscape classification of continuous field recordings around Lake George, NY
Authors: Morgan Mallory M. , Moriarty Vincent , Braasch Jonas
Published: April 2019

The amount of audio data required for long-term bioacoustics monitoring is often too large to be manually sorted. Automatic environmental sound recognition techniques are therefore applied to extract relevant acoustic stimuli and classify these stimuli after a training period. In this work, a continuous 24-h, remote audiovisual recording system was developed and deployed near a tributary stream of Lake George, NY for the automatic collection of environmental and animal sounds. Besides monitoring natural environments, this system can also be used to establish an automatic protocol for collaborative business meetings. In conjunction with the efforts of the RPI/IBM Jefferson Project to create a network of sensors continuously monitoring the lake, the goal of this research is to automatically transcribe the soundscape of the lake using a network of directional microphone arrays positioned throughout the watershed. After establishing a training database of relevant acoustic stimuli, a convolutional neural network is used to classify unprocessed audio data. Pilot studies show good results when learning takes place directly from spectrograms, since the variability of non-speech acoustic events often requires more rich detail than can be provided by MFCCs or other compressed feature sets. [Work supported by NSF #1631674, CISL, and the Jefferson Project.]
DePaul University—Holtschneider performance center
Authors: Myers Joseph W. , Hull Kirsten , Corry Brian
Published: April 2019

The DePaul School of Music has thrived for years in spite of teaching, rehearsal, and performance facilities previous facilities that were inadequate in terms of room acoustics, sound isolation and background noise. The new Holtschneider Performance Center in Chicago IL is the first and largest element in a three-phase design that utterly transforms the School of Music’s facilities, finally giving the School facilities that match the quality of the faculty and students. The new building includes a 505 seat concert hall, three recital spaces, large rehearsal rooms, classrooms, numerous practice rooms and a recording suite. With such an extensive program the main challenge was to fit the full program on an urban site while respecting zoning limits to size and height. With careful organization, heavy concrete structure and thoughtful use of isolation joints, floating slabs and resilient walls and ceilings, the building provides excellent isolation despite some challenging adjacencies. The site drove an approach in which carefully controlled footprints for the major spaces are married to generous heights.
The evolution and creation of schools for music education
Authors: Paek Hyun , Siebein Gary W. , Roa Marylin , Miller Jennifer R. , Vetterick Matthew
Published: April 2019

The creation of a school of music can begin with a vision of one person or with the necessity felt by many. Case studies of two schools of music is presented which were conceived from very different approaches. Case study one shows an evolution of a complex building that started from the use of a low ceiling classroom designed for general instruction that is now a multi-story facility that houses not only spaces for the entire music program at a college in Florida but also their entire fine arts program with a dormitory that encompasses the “live/learn” concept of the school. The second case study involves a first of its kind magnet school for the arts of a school district in Georgia that had no other facility to instruct talented students of music and fine arts on a vacant site. No instructors or directors of music was available for input in the programming and concept phases of the design and thus the design was left for the design team and the school district administrators to cooperate in generating the school's vision for the future.
A soft robotic actuation system for a bat robot
Authors: Eckman Emmet , Conk Matthew , Lunsford Sierra , Martin Charlie , Singh Agoshpreet , Sullivan Kent , Wang Yanhao , Sutlive Joseph , Müller Rolf
Published: April 2019

A crucial development in the field of biomimicry is accurately recreating the kinematics of various organisms. In the example of a bat robot in development inspired by the greater horseshoe bat, Rhinolophus ferrumequinum, this takes the form of accurately recreating fast motions of the pinnae and noseleaf observed during echolocation. In order to accurately recreate these baffle shapes it is important to choose a material that is malleable but will retain its originally molded state. An actuation system was developed to replicate the ear movement seen in the bat when using biosonar. Several actuation designs were tested, including a physical motor connection, shape memory alloys, and soft-robotic pneumatics. In addition to the actuation system, a feedback system was developed in order to accurately control the robot and provide information which could be used to determine the effectiveness of the robot. Additionally, the final challenge to assemble all the components, i.e., the baffle shapes, actuator mechanism, and feedback control mechanism, in a way that recreates the baffle motions in an effective and accurate manner.
Remote implantation of ultrasound responsive multi-cavity microparticles for early atherosclerosis
Authors: Su Xiaoqian , Thomas Reju G. , Bharatula Lakshmi Deepika , Kwan James J.
Published: April 2019

Atherosclerosis is an inflammatory disease of arteries, and results in stroke or heart attacks—the leading causes of death and disabilities in the developed world. Yet drug treatments for this chronic inflammatory disease remains to be addressed. Here, we developed a multi-cavity poly-co-lactic-co-glycolic microparticles (mc-PLGA MPs) capable of being remotely implanted at the site of arterial injury with focused ultrasound. The obtained mc-PLGA MPs present with two to five submicron surface cavities with rough inner surfaces. After exposure to high intensity focused ultrasound (HIFU) in an agarose tissue phantom, mc-PLGA MPs extravasated beyond the lumen of the channel at an average distance of 4.29 ± 1.19 mm, and sustained release of rhodamine-B for up to 15 days. Similarly, mc-PLGA MPs were able to be implanted into the sub-endothelial space of an ex vivo porcine artery model without observable damage to the artery. To further validate the drug release, we exposed a foam cell spheroids model to mcPLGA MPs and HIFU, and show that particles were dispersed throughout the spheroids and sustained delivery throughout. The results here highlight the potential for HIFU-guided implantation of mcPLGA MPs to improve local and sustained treatment of inflamed arterial tissue.
Soundscape for smart tourism in Macao
Authors: To W M , Chung Andy
Published: April 2019

This paper presents a new initiative in enhancing the experience of tourists visiting Macao, by way of appling soundscape based on the new technical specification ISO/TS 12913-2:2018.
What studies of audio-visual integration do not teach us about audio-visual integration
Authors: Maddox Ross K.
Published: April 2019

Auditory perception depends on more than just the processing of acoustic stimuli. Visual stimuli can also have a profound influence on listening. Salient examples of such effects include spatial ventriloquism—in which the location percept of an auditory stimulus is “captured” by that of a simultaneous visual stimulus—as well as drastically improved understanding of speech in noise when the talker's face is visible to the listener. These phenomena are typically described as “audio-visual integration,” and are often well modeled, as in the case of the ventriloquist effect, by ideal Bayesian causal inference. However, there is an over-reliance in these studies on single pairs of stimuli (i.e., one auditory and one visual stimulus) and the nature in which cross-modal discrepancies are resolved. This talk will first discuss two problems resulting from that: first, there is ambiguity about whether the integration occurs from weighing two independent sensory estimates or a single bound percept, and second, the design is less useful for studying integration when the stimuli are congruent. The talk will then describe recent work from our lab focused on new designs using multiple stimuli in an attempt to alleviate these issues and inform better models of integration.
Effects of geometry and mass distribution in 3D printed metastructures for vibration mitigation
Authors: Arretche Ignacio , Patil Ganesh U. , Matlack Kathryn H.
Published: April 2019

This presentation will discuss our recent progress on mechanical metastructures, which have engineered micro- and meso-scale features and are designed to have prescribed vibration mitigation properties. The goal of this work is to understand how the geometry and structure of a material can manipulate elastic wave propagation. Specifically, we developed a class of 3D printed metastructures that support low and wide band gaps, by combining periodic lattices with embedded resonant inclusions. The band gaps in these metastructures have significant shifts in frequency with small geometry changes in the unit cell design. We use finite element method simulations to calculate how band gaps in infinitely periodic metastructures depend on how the material is distributed throughout the unit cell. We study different lattice geometries that exhibit a variety of bend- and stretch-dominated deformations, as well as different volume fraction and placement of resonant inclusions. We fabricate metastructures with 3D printing and measure their frequency-dependent vibration transmission to experimentally validate their behavior. These metastructures have engineering applications in structural components that prevent the propagation of damaging structural vibrations.
Acoustical regularities in infant-directed vocalizations worldwide
Authors: Moser Cody J. , Lee-Rubin Harry , Collaboration Infant-Directed Vocalizations , Bainbridge Constance M. , Atwood Stephanie , Krasnow Max M. , Mehr Samuel A.
Published: April 2019

Adults often differentiate their song and speech between infants and other adults. Why? Is this a product of just some cultures or does it reflect a universal part of human vocal communication and human cognition? On the latter hypothesis, infant directed-song might regularly exhibit certain features across cultures, including high redundancy and repetition, high signal-to-noise ratios, and superb vowel prolongation and stability compared to adult-directed song. We built a corpus of 1614 recordings of infant- and adult-directed singing and speech produced by 411 people living in 20 societies, including hunter-gatherers and subsistence farmers. Each participant provided examples of each of the four vocalization types. Using exploratory and confirmatory analyses, we show that the acoustical features of infant-directed song and speech are universally distinct from adult-directed song and speech, especially in terms of the phonetic space of their formants, their general rhythmic structure, and their pitch range attributes.
Investigating naturalistic code-switching directed towards infants
Authors: Kremin Lena V. , Orena Adriel John , Polka Linda , Byers-Heinlein Krista
Published: April 2019

Mixing two languages in speech (i.e., code-switching) is prevalent in multilingual settings, including in speech directed towards infants. Prior research suggests a link between parental code-switching and vocabulary size (Byers-Heinlein, 2013). Moreover, laboratory work suggests that some types of code-switching appear more difficult for infants to process than others (Byers-Heinlein et al., 2017; Potter et al., 2018). This raises the possibility that the effects of parental code-switching depend on the parents’ specific behavior in terms of the frequency, location, and purpose of code-switching (Byers-Heinlein, 2017). Prior studies of parental code-switching relied on self-report or short lab observations. In this study, we analyze parental code-switching behavior in a corpus of daylong home recordings of 21 infants (at 10- and 18-months) from French-English bilingual families in Montréal. We will identify instances of parental code-switching, their syntactic location, the direction of the switch, and the apparent reason for the switch (e.g., teaching vocabulary, translating an entire utterance). Preliminary results indicate that the frequency of code-switching varies between families and that code-switching between sentences is more common than code-switching within a sentence. This project will provide the first in-depth investigation about the characteristics of naturally produced parental code-switching.
Estimates of coherent reflection loss inclusive of the effects of near-surface bubbles on sound speed
Authors: Jones Adrian D. , Zinoviev Alex
Published: April 2019

Through simplification of the authors’ model “JBZ” of coherent reflection loss at the ocean surface, a revised model has been obtained in extremely simple form. This model provides descriptions of the loss obtained at a wind-roughened surface, adhering to a Pierson-Moskowitz surface wave frequency spectrum, inclusive of the effects of near-surface bubbles on sound speed. A very compact form of the model has been obtained for application to surface ducted sound for a wide range of wind speed and frequency combinations, with the result that the dB loss with range is the same for all modes within the duct. The derivation of the model from the authors’ earlier JBZ is described, and the conditions for equivalence are detailed. In a limited range of comparisons, descriptions of reflection loss per bounce obtained with the original JBZ and the compact version are shown to be nearly identical to corresponding values obtained by the “Relay” model described by Ainslie [JASA 118, 3513–3523 (2005)].
Estimation of parameters quantifying porosity in random porous structures using ultrasonic attenuation: Solving the inverse problem
Authors: Yousefian Omid , White Rebekah , Banks H. T. , Muller Marie M.
Published: April 2019

The goal of this study is to estimate the porosity (pore size and density) of numerically simulated random porous three-dimensional structures mimicking simplified geometries of cortical bone using attenuation of ultrasonic waves in the MHz range. To do so, we use a physics-based model derived from the Independent Scattering Approximation (ISA) to mathematically model the attenuation of elastic waves in porous structures as a function of the parameters that we wish to identify: pore size and density. Frequency-dependent attenuation data are generated using three-dimensional finite-difference time-domain simulations in the range of 1–8 MHz in mono-disperse structures with the pore diameter and density ranging from 100 to 200 µm and 20–50 pore/mm3, respectively. We then solve an ordinary least squares (OLS) inverse problem to recover the pore size and density by minimizing the sum of squared errors between the simulated data and the model prediction. In doing so, we demonstrate that we can estimate with confidence the parameters quantifying porosity using the ISA model given three-dimensional numerically simulated attenuation data.
Spectro-temporal templates unify the pitch of resolved and unresolved harmonics
Authors: Shamma Shihab , Dutta Kelsey J.
Published: April 2019

Pitch is a fundamental attribute in auditory perception that is involved in source identification and segregation, music, and speech understanding. When harmonics are well-resolved, the induced pitch is usually salient and precise; however, when the harmonics are not completely resolved, the pitch percept becomes less salient and poorly discriminated. Previous models relying on harmonic spectral templates have been able to account fully for the pitch of the resolved but not of the unresolved harmonics. I will describe a biologically motivated model of templates that combine both spectral and temporal cues to estimate both pitch percepts. Specifically, the pitch of unresolved harmonics is estimated through bandpass filters implemented by resonances in the dendritic trees of neurons in the early auditory pathway. It is demonstrated that organizing and exploiting such dendritic tuning can arise spontaneously even in response to white noise. We show how these temporal cues become integrated with those of spectrally resolved harmonics, effectively creating spectro-temporal harmonic templates for all pitch percepts. We finally discuss how this approach can account for all major monaural pitch percepts, as well as pitch percepts evoked by dichotic binaural stimuli.
Theory of sound propagation through a fluidic medium with suspended clay and silt particles having the general characteristics of mud
Authors: Pierce Allan D. , Siegmann William L. , Brown Elisabeth M.
Published: April 2019

Work presented at previous meetings and in various publications for propagation of sound through mud continues with a theory that simultaneously takes into account viscous flow past both suspended clay and silt particles. Why silt particles do not settle under the action of gravity to the bottom of the layer is explained because (1) the clay particles adhere together in a flocculated card-house configuration and (2) the silt particles are trapped in the clay matrix. The conjecture is defended that the clay matrix and the silt particles move in lock-step under the influence of an incident sound wave. Neighboring particles of different sizes move with the same velocity amplitude, although they are subjected to different viscous forces. The theories of Stokes, Happel, and Brenner are used to calculate viscous forces at low frequencies for particles of different shapes, with the clay particles idealized as thin platelets and the silt particles idealized as spheroids with different eccentricities and random orientations. The forces on the clay particles continue to be given by the low frequency approximation for all frequencies of interest, and the deviations from Stokes's low frequency law are taken to be what corresponds to a sphere with the equivalent radius. The size distributions of the particles are taken from existing data. Modified fluid dynamic equations are derived using basic principles. The attenuation is shown to vary as frequency squared at low frequencies and as the square root of frequency for higher frequencies.
Distinguishing peripheral and central contributions to speech context effects
Authors: Oxenham Andrew J.
Published: April 2019

Acoustic context effects often function in a spectrally contrastive manner and can contribute to achieving perceptual constancy of speech sounds under widely varying conditions, including different room acoustics, different talkers, and different background noises. The neural mechanisms underlying these effects remain unknown, but they are likely to involve within-channel adaptation and across-channel inhibition, similar to that postulated for non-speech auditory context effects, such as auditory enhancement. These mechanisms could be instantiated as early as the cochlea, via efferent circuits, but may also involve higher-level processes. All such mechanisms could in principle be modulated by expectation and attention. Work from our lab has attempted to shed light on the nature and locus of the mechanisms underlying auditory and speech context effects, using a combination of techniques, including behavior, otoacoustic emissions, and electroencephalography (EEG). The results so far suggest that context effects can be somewhat modulated by attention, and may involve stages of auditory processing that extend to subcortical regions, but seem unlikely to involve changes in cochlear mechanics. [Work supported by NIH grant R01DC012262.]
Calculating the full leaky Lamb wave dispersion characteristics
Authors: Kiefer Daniel A. , Ponschab Michael , Rupitsch Stefan J.
Published: April 2019

Lamb waves are mechanical waves guided in a plate with stress-free boundaries. In practice, the plate is often in contact with a fluid. The propagation of guided waves may change substantially in this case due to interaction with the adjacent medium, e.g., acoustic radiation may lead to leakage of energy into the fluid domain. The resulting plate modes are called leaky Lamb waves, and their attenuation due to leakage is an important parameter for the design of ultrasonic devices that exploit such waves. Modern methods to calculate dispersion characteristics of guided waves, i.e., the wavenumber-frequency relationship, solve the corresponding discretized eigenvalue problem. This kind of model for leaky Lamb waves with the analytically exact fluid interaction leads to a nonlinear eigenvalue problem, which is difficult to solve. We present a change in variables that yields an equivalent polynomial eigenvalue problem. The latter can be rewritten as a linear eigenvalue problem in state space. As a result, conventional numerical eigenvalue solvers can be used to robustly determine the sought wavenumbers. In contrast to traditional root-finding of the characteristic equations, the presented method guarantees to find all solutions and naturally handles complex wavenumbers. Additionally, no initial guesses for the wavenumbers are required.
Nonlocal homogenisation scheme for lossless and anisotropic metafluids and phononic crystals
Authors: Nemati Navid , Guilleminot Johann , Silveirinha Mário G.
Published: April 2019

We present a systematic homogenisation approach to describe macroscopic dynamics of generic periodic acoustic materials composed of a rigid structure filled with a lossless fluid. This approach takes temporal dispersion as well as spatial dispersion effects into account, and can characterise, in a general manner, the oblique propagation and anisotropic effects. The theory is formulated such that all effects are encoded in, only, the effective frequency and wavevector dependent density, which can be calculated through a source-driven problem. Also, we demonstrate that the theory can homogenise materials even in frequency band gaps, including those that correspond to local-resonance phenomena or to Bragg scattering.
Detecting changes in lingual differentiation over the course of speech sound intervention
Authors: Kabakoff Heather M. , Feeny Graham T. , Tiede Mark , Preston Jonathan L. , McAllister Tara
Published: April 2019

“Lingual differentiation” describes the ability to articulate different regions of the tongue semi-independently. Children with speech sound disorder (SSD) exhibit fewer differentiated gestures than typically developing children (Gibbon, 1999) and show a greater degree of lingual differentiation after treatment than before treatment (Preston et al., 2018). In the current study, four preschool-aged children (4;1-5;4) were treated for error patterns identified on the HAPP-3 measure in 18 sessions of cycles treatment (Hodson and Paden, 1983) over six weeks. Ultrasound and audio recordings were collected as children named pictures containing a variety of target sounds at pre-treatment, during six within-treatment sessions, and at post-treatment. For each production, lingual contours were extracted from midsagittal ultrasound images and quantified using two complexity metrics: modified curvature index (Dawson et al., 2016) and number of inflections (Preston et al., 2018). Trained listeners transcribed each production and calculated the percentage consonants correct (PCC) at each time point using Phon speech analysis software (Hedlund and Rose, 2016). We ask whether incremental changes in lingual differentiation are detectable in preschool-aged children enrolled in treatment, and whether these changes correlate with the increase in production accuracy (PCC). We also examine gradient differences in lingual complexity for rhotic tokens transcribed as misarticulated.
Differential impact on speech production from chronic thalamic DBS in Essential Tremor and that from STN DBS in Parkinson's disease
Authors: Wang Emily , Verhagen Metman Leonard A.
Published: April 2019

Essential Tremor (ET) is the most common tremor syndrome seen in adults. The characteristic tremor in ET is postural and action tremors, with a frequency of 4–7 Hz; while in patients with Parkinson’s disease (PD), the dominant tremor is resting tremor with a typical frequency of 5 Hz. Deep brain stimulation (DBS) in the ventral intermediate nuclei (Vim) has been shown effective in treating action or intention tremors in medically resistant ET, while DBS in the subthalamic nucleus (STN) has been shown effective in treating rigidity, rest tremor and Dopa-induced dyskinesias in PD. However, chronic bilateral DBS, whether in Vim or STN, may have negative impact on speech production. We report two cases where both patients received DBS greater than one year and developed speech impairment. When the stimulation in Vim was turned off for 30 min in ET, the patient's speech returned to the baseline while turning the STN stimulation off for 30 min in PD, minimal changes were observed and 12 h with stimulation-off were required for speech to return to the non-stimulated state.
Response times of repeated nonwords in children with residual speech sound disorder
Authors: Spencer Caroline E. , Cuervo Sisan , Baldinelli Natalie , Sheehan Caroline , Boyce Suzanne
Published: April 2019

Nonword repetition (NWR) is sensitive to impairments in a range of disorders, including speech sound disorders (Larrivee and Catts, 1999). NWR requires listeners to perceive an auditory stimulus, store the perception in working memory, and repeat the stimulus aloud when prompted. Response time—from stimulus presentation to participant response—can be measured to assess processing speed. Deficits in each of these processes have been linked to speech sound errors in young children (Bird, et al., 1995; Lewis, et al., 2011; Preston, et al., 2015; Rvachew, et al., 2003), but research from older children with residual speech sound disorders (RSSD) is lacking. To evaluate processing speed in children with RSSD, we have adapted a nonsense Syllable Repetition Task (SRT; Shriberg et al., 2009). The SRT consists of multisyllabic nonsense words that use targeted phonemes (/b, d, m, n, ɑ/), to minimize the possibility of articulation difficulties masking the skills intended to be studied—phonological processing. Response times on 2-, 3-, and 4-syllable nonwords will be compared between children with RSSD and children with typically developing speech. Based on preliminary findings, we suspect that response times of children with RSSD are slower than those of children with typical speech. The results will be discussed.
Classification of accurate and error tongue movements for /r/ in children using trajectories from ultrasound
Authors: Li Sarah R. , Dugan Sarah , Annand Colin , Woeste Hannah M. , Masterson Jack A. , Boyce Suzanne , Mast T. Douglas , Riley Michael A.
Published: April 2019

American English /r/ is considered the most difficult sound to remediate in children with speech sound disorders. The sound is complex, requiring coordinated, quasi-independent tongue movements, making it challenging to remediate in speech therapy. However, there are few clinical tools that allow for a quantitative, real-time display of the dynamics of tongue part movements. We aim to fill this need by developing a real-time, simplified, interactive biofeedback system that transforms ultrasound image data to a visual feedback object and quantitative data stream. In this presentation, we compare blade, dorsum, and root displacement trajectories determined from midsagittal ultrasound imaging of children with residual speech sound disorders (RSSD) and children with typical speech, using principal component models and cluster analysis techniques. Results show a trend of smaller tongue part displacements for RSSD children compared to children with typical speech. The analysis also elucidates distinct strategies for production of accurate /r/. We compare our classification of accurate and error tongue movements to perceptual judgments from trained listeners. Preliminary results suggest strong correspondence between our trajectory-based classification and listener judgments of /r/ accuracy.
Hybrid Cramer-Rao bound for near-field source localization using a spatially spread acoustic vector sensor
Authors: Morris Zakayo Ndiku , Wong Kainam Thomas , Han Yuting
Published: April 2019

This presentation characterizes the source-localization precision obtainable via "received signal strength indication" (RSSI) based on data from a tri-axial velocity sensor and a spatially separated pressure sensor. That scheme was proposed originally by Y. I. Wu and K. T. Wong in January 2012 in the IEEE Transactions on Aerospace and Electronic Systems. That source-localization scheme depends on the acoustic propagation path-loss exponent, which is typically not precisely known a priori but could be modeled stochastically. That exponent may also differ in value for the propagation path to the tri-axial velocity sensor and for the propagation path to the pressure sensor. This presentation accounts for these two practical considerations in characterizing the scheme's source-localization precision, through the metric of the "hybrid Cramer-Rao bound" (HCRB), the correctness of which is here validated by Monte Carlo simulations of the corresponding "maximum a posteriori" (MAP) estimator.
Modeled position and intensity statistics in deep water caustics
Authors: Woolfe Katherine F. , Spofford Chuck , Vayur Kritika , Mikhalvesky Peter
Published: April 2019

Caustics are a form of natural focusing that occurs in deep water acoustic propagation, but acoustic intensity and position perturbations at caustics have not been investigated in detail. The positions, shapes, and intensities of caustics and cusps are controlled primarily by the large-scale sound speed profile, with perturbations primarily caused by deterministic features (fronts, eddies) and stochastic features (internal waves). We selected two representative deep water environments for our analysis: a north Pacific site and temperate profile. For each region, 100 independent and 100 time-coherent realizations of internal waves were generated. The model uses the statistics provided by the Garrett-Munk power spectrum to generate displacements, which are converted into sound speed realizations. In the north Pacific profile, internal waves were concentrated primarily in the upper 200 m of water. In the temperate profile, internal waves were concentrated in the upper 700 m of water. We used a Gaussian beam model to analyze position and intensity statistics of caustics for both types (independent and time-coherent) of internal wave fields at each site as a function of frequency, internal wave strength, and source depth. Simulations indicate that caustics are more stable than other portions of the acoustic field and that this stability is a function of internal wave strength and caustic location. This work is approved for public release, Distribution Unlimited.
Antivascular photo-mediated ultrasound therapy and its application in the eye
Authors: Yang Xinmai , Paulus Yannis M. , Wang Xueding
Published: April 2019

Antivascular therapy can improve the prognosis of a variety of pathological conditions, including cancer and many eye diseases. By synergistically applying laser pulses and ultrasound bursts, we developed a photo-mediated ultrasound therapy (PUT) technique as a localized antivascular method. PUT takes advantage of the high native optical contrast among biological tissues and has the unique capability to self-target microvessels without damaging surrounding tissue. The technique utilizes an integrated therapeutic ultrasound and laser system. The laser system emits 5-ns, 10-Hz pulses, which is synchronized with 10-ms, 10-Hz ultrasound bursts. Experiments were carried out on chicken yolk sac membrane and rabbit eyes. With radiant exposures around 5 mJ/cm2at 532 nm and ultrasound pressures around 0.4 MPa at 1 MHz or 0.5 MHz, microvessels were able to be removed. Furthermore, ex vivo tests with human blood demonstrated that cavitation was induced when laser and ultrasound were utilized synergistically. On the rabbit eye model, the blood flow in microvessels could be greatly reduced after PUT, and the occlusion of microvessels could last up to 4 weeks. In conclusion, PUT holds significant promises as a non-invasive method to precisely remove microvessels in neurovascular eye diseases by more selectively treating vasculature with minimized side-effects.
Combining light and sound with nanoparticles to identify and treat head and neck cancers
Authors: Egnuni Teklu , Chunqi Li , Ingram Nicola , Coletta Louise , Freear Steven , McLaughlan James R.
Published: April 2019

High intensity focused ultrasound (HIFU) is a non-invasive and non-ionising approach used primarily for the thermal ablation of cancerous tumours. Even though it has been in clinical use for over 30 years, it has yet to achieve widespread use. Two key limitations for this approach are long treatment times and a difficulty in getting real-time feedback on treatment efficacy. One technique that could help with these limitations is a combination of HIFU, pulse laser illumination, and cancer targeted nanoparticles. When nanoparticles are simultaneously exposed to these modalities, vapour bubbles form, providing a controllable way to nucleate cavitation in the target location. Acoustic emissions from inertial cavitation can be monitored via passive cavitation detection and/or mapping. This approach provides direct localisation of cancerous regions and has greater sensitivity compared with current photoacoustic imaging. Once the cancerous regions have been localised, they can be ablated by HIFU, which is known to be enhanced in the presence of cavitation, by enhancing thermal damage in a localised region. Furthermore, the acoustic emissions generated during these ablations could give an indication of treatment progress. This study will present data on both in vitro and in vivo validation of this approach in models of head and neck cancer.
Acoustic metamaterials and additive manufacturing
Authors: Haberman Michael R.
Published: April 2019

Acoustic metamaterials (AMM) have captured the attention of a wide range of researchers for their potential to create materials with properties or functionality that exceed naturally occurring materials or conventional composites. Progress in acoustic metamaterials is largely the product of a combination of technological advances that have been made in the past three decades. Specifically, AMM research is a prototypical example of novel concepts in physics converging with advances in technology, primarily additive manufacturing and widespread access to robust computational tools. Additive manufacturing is a key component to this area of research since it allows for rapid build and test cycles as well as the production of elaborate structures for acoustic wave manipulation that follow from rigorous mathematical predictions. This talk will highlight physical concepts central to AMM research and the role that advanced manufacturing processes play in present and future research. It will then discuss the significant technical challenges that must be overcome if AMM are to be brought to their full potential, including the need to fabricate large amounts of subwavelength dynamic microstructure spanning orders of magnitude in length scale.