bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling outdoor sound propagation in urban environments
Authors: Kamrath Matthew , Maillard Julien , Jean Philippe , Van Maercke Dirk , Picaut Judicaël
Published: May 2016

Modeling outdoor sound propagation in cities is challenging because they often have complicated geometries and large domain sizes. One hybrid approach uses an engineering method (e.g., Harmonoise or Nord2000) with an extra attenuation term for interactions with complicated geometries like a T-barrier. The extra term quantifies the additional attenuation from the complex geometry compared to a reference geometry that can be modeled in the engineering method. Calculating pressure levels using a detailed method such as the Boundary Element Method (BEM) for the complex and reference geometries over multiple source and receiver positions and frequencies yields a table of excess attenuations. Interpolating this table of corrections at the desired source/receiver location and frequency produces the desired relative attenuation. This presentation discusses the development of this method for a case that has multiple propagation paths due to reflections from buildings and one interaction with a complex geometry per path but no additional diffraction points. The hybrid method agrees well with 3D BEM calculations at low frequencies.
Toward quantifying community response to crackle-containing jet waveforms
Authors: Gee Kent L. , Vaughn Aaron B. , Neilsen Tracianne B. , Miller Kyle G. , James Michael M. , Salton Alexandria R. , Downing J. M.
Published: May 2016

Although the phenomenon referred to as “crackle” has been previously described to be a dominant and annoying component of high-power military jet noise, its actual subjective impact is poorly understood. One of the challenges in quantifying jet crackle has been the identification of suitable metrics that are sensitive to the randomly occurring acoustic shocks responsible for the crackle percept [Gee et al., J. Acoust. Soc. Am. 121, EL1–EL7 (2007)]. This paper describes why understanding crackle could influence community perception of jet noise and recent waveform analyses of military jet noise that may provide insights how the phenomenon can be quantified perceptually. [Work supported by the USAFRL SBIR program.]
The effects of horizontal shading device orientation and surface material and the use of a compact silencer in forming acoustical barriers for a ventilated glass double skin facade
Authors: Lee Jeehwan , Chang Jae D. , Coffeen Robert C.
Published: May 2016

Acoustical discomfort due to traffic noise transmission via operable windows is a significant environmental stress for building occupants in urban areas. A ventilated double skin facade, DSF, can potentially address the issue of noise transmission and operable windows. A hypothetically designed glass DSF mock-up was constructed in the opening between the reverberation rooms at the University of Kansas to determine the noise reduction of the DSF mock-up based on the orientation and surface materials of the horizontal shading devices and the use of a compact silencer in place of a typical ventilation grille in the outer skin opening. The compact silencer provides natural ventilation by allowing outside air to flow within the cavity of the DSF. For these laboratory tests, the horizontal shading devices with sound absorbing material were oriented at 0, 30, 60, and 90 degree angles. The laboratory noise reduction measurements are presented for the mock-up with the several shading device orientations and materials and for the use of a compact silencer.
Eigenfunction analysis of the Green's function parabolic equation
Authors: Gilbert Kenneth E.
Published: May 2016

The Green's function parabolic equation (GFPE) algorithm was originally derived using operators, functional analysis, and Green's functions [K. E. Gilbert and X. Di, J. Acoust. Soc. Am. 94, 2343–2352 (1993)]. This presentation demonstrates that the GFPE algorithm can be obtained more simply and directly in terms of the eigenfunctions of a homogeneous atmosphere over a complex impedance ground surface. The eigenvalue-eigenfunction equations obtained follow naturally from the basic and well-known separation of variables method. The eigenfunctions, which are fundamental solutions of the Helmholtz equation, consist of plane waves plus a surface wave. The plane waves have a continuous wave number spectrum while the surface wave has a single, discrete, complex wave number. A physical explanation is given for the existence of the surface wave. It is shown that eigenfunction expansions give concrete meaning to abstract operator solutions for one-way propagation. Using the notion of a function of an operator and an eigenfunction expansion of the acoustic field, the GFPE can be obtained simply and concisely.
Design and evaluation of a new ultrasonic horn for viscosity reduction of heavy oil
Authors: Yang Yan , Wang Xiuming , Xu Delong
Published: May 2016

Based on the basic principle of the sandwich piezoelectric transducer, a high-power ultrasonic horn which can be used for viscosity reduction of heavy oil and pour point reduction of crude oil with high pour point was proposed and designed. The basic frequency of the horn is 16.8 kHz, and the input electrical power is 1 kw. It can work continuously on the industrial scale. First, the impedance characteristic was derived for the simplified model of the sandwich piezoelectric horn on the basis of equivalent network method. Second, its properties such as the resonance frequency, conductance, and transmitting voltage response were simulated by using of ANSYSsoftware in air, water, and silicone oil, respectively. According to the simulation, a prototype was made and measured by an impedance analyzer. Its basic frequency is in good agreement with the simulation calculation. The result shows that this high-power ultrasonic horn is expected to be applied on the industrial scale in viscosity reduction of heavy oil and ultrasonic sludge disintegration.
Effects of various acoustic stimuli on higher order thinking and tinnitus perceptions
Authors: Cobabe Andrew , Munoz Karen , Sinex Don , Larsen Jeffery
Published: May 2016

Masking sounds are often employed in the management of subjective tinnitus to desensitize and divert attention. The potential side effects of these maskers in distraction from other thought processes is not well understood. This research addresses the effects an artificial tinnitus and broadband masking or distracting stimuli have on performance of challenging cognitive or attention tasks. Masking sound preferences were also assessed. Adults with normal hearing and without thought processing disorders performed a two-back (n-back) auditory memory task in listening conditions including silence, white noise, classical music, pop music, and an artificial tinnitus condition. Participants also completed a survey, rating perceptions of their performance and attentional preferences for the sounds. Data show a greater distraction effect for more complex stimuli (pop music). Natural environmental sounds or white noise are favored to pop music for tinnitus masking. It is suggested that tinnitus maskers with more complex meaning including singing, language, and speech appear to have a more multifaceted effect on attention. Although this may be desirable for effective tinnitus masking, the impact on other thought processes appear to be present but unintended. The irrelevant sound effect (ISE) of tinnitus maskers warrants further investigation.
Examination of middle-ear function through interspecies comparison of middle-ear transmission characteristics
Authors: Lemons Charlsie , Meaud Julien
Published: May 2016

Lumped parameter ossicular chain models for several mammals have been developed; by comparing model parameters and the input and output characteristics of these models, conclusions can be drawn about the relative middle-ear transmission characteristics between different species allowing for a better understanding of the middle-ear’s overall role in hearing. The tympanic membrane plays a significant role in middle-ear function: experiments show that the forward and reverse transmission characteristics of the middle-ear are affected by the tympanic membrane, especially at high frequencies. Thus, understanding the behavior and transmission characteristics of the tympanic membrane is vital in understanding overall transmission through the middle-ear. By examining the interaction between lumped parameter ossicular chain models and tympanic membrane models from several animals and by comparing normalized two-port matrix parameters from several species, observations regarding differences in middle-ear behavior between species are drawn.
Functional characterization of auditory forebrain in the songbird
Authors: Elliott Taffeta M. , Theunissen Frédéric E.
Published: May 2016

Songbirds communicate with individualized vocalizations that must be discriminated and recognized based on the detection of complex sound features. Neurons in the primary auditory nucleus of the zebra finch, field L, specialize in extracting auditory features that include rapid fluctuations in temporal envelope, harmonic structure, and dynamic pitch changes. Weused electrophysiological recording and immunohistochemistry to determine the inhibitory network roles and putative connectivity of field L neurons that represent specific kinds of acoustic features. Neuronal responses to conspecific song broadcasts were recorded juxtacellularly from an in vivo anesthetized preparation. At the end of recordings sufficient to calculate a spectrotemporal receptive field (STRF), the cell was filled with Neurobiotin from the patch electrode. Some projections could be traced. A slight majority of recovered auditory neurons were GABA-ergic based on double fluorescent labeling of the Neurobiotin and an antibody for glutamic acid decarboxylase (GAD). The STRFs of the recovered neurons showed a diverse sampling of complex and simpler types of auditory selectivity. This variety should be useful in distinguishing signature features of particular individuals' songs. We hypothesize that uneven distribution of tuning across morphological types and anatomical locations superficial within field L contributes to parallel pathways dedicated to processing distinct categories of acoustic features.
Cortical oscillatory signatures of active listening complement brainstem coding measures in predicting listening performance
Authors: Bharadwaj Hari M. , Choi Inyong , Shinn-Cunningham Barbara
Published: May 2016

Following the finding of cochlear deafferentation (“synaptopathy”) in noise exposure and aging in animal models (Kujawa and Liberman, J. Neurosci. 2009; Sergeyenko et al., J. Neurosci. 2013), there is considerable interest among hearing scientists and clinicians to investigate the presence and consequences of synaptopathy in humans. In the laboratory, human subjects with clinically normal hearing (NH) listeners from the general population exhibit large individual differences in suprathreshold perceptual ability. Through a recent series of experiments using otoacoustic emissions and electrophysiology, we studied these individual differences and showed that they partly arise from differences in subcortical coding of temporal information consistent with synaptopathy (Bharadwaj et al., J. Neurosci. 2015). In the current study, we examined cortical oscillations accompanying cued preparation to selectively attend to a target spatial location as a correlate of top-down active listening. We find that both brainstem envelope-following responses (EFRs) and cortical oscillations independently correlate with performance. EFRs and cortical oscillations together explain a greater fraction of the variance across individuals than EFRs alone. Our results point to a mechanism by which some listeners with good subcortical coding may still perform poorly, and a technique that might be employed to isolate sensory coding contributions to suprathreshold hearing deficits.
Age-related effects on two-tone suppression and consonant perception in noise
Authors: Hegland Erica L. , Francis Alexander L. , Strickland Elizabeth A.
Published: May 2016

Two-tone suppression reduces gain in the cochlea nearly instantaneously in a frequency-dependent manner. In speech perception, suppression may enhance spectral contrasts between regions of higher and lower energy. A few previous studies have investigated the effects of aging on suppression and correlations with speech perception in noise, but none have looked at the adaptability of suppression with preceding stimulation. In the present study, estimates of two-tone suppression and consonant perception were measured in younger and older adults. Suppression was measured with short tonal stimuli with and without preceding stimulation. Consonant vowel (CV) stimuli consisted of combinations of the consonants /b, g, d/ and the vowels /ɑ, i, u/ spoken by three male speakers. Broadband noise was filtered to match the long-term average spectrum of the speech stimuli used. CV onset was either 0 or 70 ms after onset of the noise. Participants were asked to identify the consonant by choosing /b/, /g/ or /d/. Percentage correct was calculated for CVs in quiet and in + 5, 0, −5, and −10 dB signal-to-noise ratio conditions. Suppression and adaptability were found to correlate with several aspects of speech perception in noise. Age-related results and implications will be discussed. [Research supported by NIH(NIDCD)F31 DC014395.]
Contributions of individual frequency bands to the loudness of broadband sounds assessed by loudness matching
Authors: Jesteadt Walt , Brunette Katyarina E. , Walker Sara M. , Thrailkill Katie
Published: May 2016

Data obtained in sample-discrimination tasks indicate that subjects place high weight on the lowest and highest frequencies when making judgments concerning the loudness of broadband stimuli. In an effort to determine whether these judgments are truly based on loudness, six subjects with normal hearing were tested in a loudness matching task where the stimuli consisted of 15 bands of noise, each two critical bands wide, or 15 tones at the center frequencies of those noise bands. In addition to comparing all combinations of 15-component noise and 15-component tone stimuli, subjects adjusted the level of 15-component stimuli to equate them in loudness with stimuli missing the lowest, middle or highest component. This was done for stimuli with equal levels for each component and for levels approximating the long term average speech spectrum. Noise stimuli had to be increased by 2.5 dB to be equal in loudness to tonal stimuli. Full bandwidth stimuli had to be decreased in level by 1.4–1.8 dB to be equal in loudness to stimuli missing the highest frequency band or tone. The effect was smaller if the middle component was missing and near zero if the lowest component was missing. [Work supported by NIH.]
Binaural-cue weighting in free-field localization of narrowband noises presented with open-fit hearing aids and in simulated reverberation
Authors: Diedesch Anna C. , Stecker G. C.
Published: May 2016

Interaural time (ITD) and level differences (ILD) are susceptible to distortion by multipath acoustics due to reverberation, echoes, and potentially with open-fit, behind-the-ear (BTE) hearing aids, which pose an additional delay between acoustic and processed sound (~2–5 ms). Here, young, normal hearing listeners localized narrow bands of noise centered at 500 or 4000 Hz. Listeners were fit with linear amplification and evaluated in three aided conditions: unaided, open-fit, and occluded BTE coupling. Target sounds were presented over loudspeakers spanning ±610 azimuth, in anechoic and simulated room conditions. Performance was assessed across conditions by measuring localization gain (slope), variability (R2), accuracy, and front-back error rate. Results show greater variability in the simulated room than anechoic conditions, particularly for aided conditions (occluded > open > unaided). Aided listening also flattened localization gain, particularly at 4000 Hz. Findings are consistent with acoustic recordings that show reduced ILD and erratic ITD in simulated rooms. The results can be quantified in the form of binaural-cue weighting (ITD/ILD “trading ratio”) on the basis of cue values extracted from in-ear recordings obtained for each listener and condition (Diedesch and Stecker 2016, Assoc. Res. Otolaryngol. Abs. 39). [Work supported by NIH R01-DC011548.]
Contribution of near- and suprathreshold hearing deficits to speech recognition
Authors: Warzybok Anna , Pieper Sabrina , Verhulst Sarah
Published: May 2016

This study addresses the contribution of audibility and suprathreshold deficits to speech recognition in quiet, stationary, and speech-modulated noise. The relative importance of these deficits for different frequency ranges of hearing was determined by measuring speech recognition using broadband speech and noise, but also high- and low-pass filtered versions of these stimuli. Audibility was assessed using pure tone thresholds and speech reception thresholds (SRT) in quiet. Three listener groups were considered to parse out hearing deficits: young (yNH) and older normal-hearing (oNH) listeners and hearing-impaired (HI) listeners. oNH and HI listeners performed equally poor in stationary noise where yNH listeners showed significantly better SRTs in both noise conditions. Since audibility did not correlate with SRTs in stationary noise but with modulated noise, and SRTs in stationary and modulated noise correlated with each other, a common mechanism (not audibility) must affect speech recognition in noise. Furthermore, our results suggest that performance in the broadband condition cannot be explained by the low frequency mechanisms since all groups performed similar in the low-pas conditions whereas the oNH and oHI group performed equally bad in high-pas condition. Instead, we found evidence for a contribution of high frequency envelope coding mechanisms to broadband performance
Contributions to high-frequency reflectance from the change in diameter between sound-delivery tube and ear canal
Authors: Lewis James D. , Easterday Mary
Published: May 2016

Measurement of wideband reflectance requires stimuli to be delivered to the ear canal through a tube with diameter seven-times smaller than that of the average canal. This discontinuity may contribute to the measurement-location sensitivity of reflectance above 5 kHz [Lewis and Neely. (2015). J. Acoust. Soc. Am. 138, 977–993]. To test this hypothesis, reflectance was measured at different locations in a set of artificial ear canals (cylindrical tubes with diameters of 8, 9, and 10 mm) terminated by an IEC711 coupler, and compared to the theoretical reflectance. The measured reflectance exhibited a high-frequency notch that (1) decreased in frequency as distance between the probe and coupler increased and (2) increased in magnitude as canal diameter increased. The theoretical reflectance lacked the high-frequency notch of the measured reflectance; however, it was possible to simulate the measured data by adding an inductance in series with the canal model [Karal. (1953). J. Acoust. Soc. Am. 25, 327–334]. Transforming the impedance measured in the artificial canals to remove the estimated inductance decreased the notch depth and measurement-location sensitivity of the measured reflectance, especially for the larger diameter canals. Additionally, the measured reflectance more-closely approximated the theoretical reflectance. Findings have implications for in-situ sound-level calibrations.
A study on the effects of depression using the weighting white noise
Authors: Bae Seonggeon , Bae Myungjin
Published: May 2016

In general, depression is a disease that appears negative emotions and changes negative emotions in brain function. Fifteen percentage of the population suffers from anxiety disorders and depression at least once during a lifetime. Delta waves are often found to increase in depressed patients than in the general population, which cause negative emotions. The alpha waves increases in the left frontal lobe, and the beta waves increases in the right frontal lobe. Depending on the brain waves, patients with depression have such characteristics. In this study, we used a white noise for the symptoms of depression. Analysis of depression in a white noise is advantageous than the using EEG features. White noise weight has an effect on depression.
The physics of auditory proximity: Auditory mechanisms that extract pitched signals from noise and other signals
Authors: Griesinger David H.
Published: May 2016

Cutthroat evolution has given us seemingly magical abilities to hear speech in complex environments. For example, we can tell instantly, independent of timbre or loudness, if a sound is close to us. In a crowded room, we can switch attention at will between at least three different simultaneous conversations, and involuntarily switch to one of them if our name is spoken. These feats are only possible if, without conscious attention, each voice has been separated into an independent neural stream. The separation process relies on the phase relationships between the harmonics above 1000 Hz that encode speech information, and the neurology of the inner ear that has evolved to detect them. When phase is undisturbed, once in each fundamental period harmonic phases align to create massive peaks in the sound pressure at the fundamental frequency. Pitch-sensitive filters can detect and separate these peaks from each other and from noise with amazing acuity. But reflections and sound systems randomize phases, with serious effects on attention, source separation, and intelligibility. This paper will describe the many ways ears and speech have co-evolved, and recent work on the importance of phase in acoustics and sound design.
Not just fishes: Dick Fay’s contributions to frog bioacoustics
Authors: Simmons Andrea M.
Published: May 2016

In addition to his many conceptual and technical contributions to fish bioacoustics, Dick Fay also guided and influenced research into the auditory worlds of anuran amphibians. In this talk, I will highlight the impact of Dick’s scientific career on the understanding of frog bioacoustics. Topics covered will include the use of the shaker table system, which Dick designed to quantify directional hearing in fishes, to the study of pressure and particle motion sensitivity in bullfrog tadpoles; the importance of temporal coding in the auditory nervous system for mediating periodicity perception; and the use of psychophysical experiments for generating hypotheses about the evolution of hearing.
Comparison of psychoacoustic abilities in many vertebrate species
Authors: Long Glenis
Published: May 2016

Psychoacoustic research with non-human species is very time consuming, but provides invaluable information about the underlying bases of hearing and its importance to humans and other species. Although most of Dick Fay's research has been evaluated the psychoacoustic abilities of one species of fish, he consistently compared this data with similar data from other vertebrates. He was not content to present data from one or two other species, but searched the literature to ensure that all possible comparisons were accessed to produce excellent figures combining this data. He made all the data he extracted from the literature available in an invaluable book (Fay, R. R. (1988). Hearing in Vertebrates: A Psychophysics Databook. Winnetka, IL: Hill-Fay Associates). This data are now being made available online on http://www.fayfoundation.org/category/hearing-in-vertebrates-a-psychophysics-databook/, a tool which will continue to stimulate research into the similarities and differences of psychoacoustic abilities in vertebrate species.
Ever expanding applications in medicine and biology
Authors: Yengul Sanjay S. , McDannold Nathan
Published: May 2016

The Technical Committee on Biomedical Acoustics is one of the most diverse groups in the Acoustical Society of America. It is comprised of individuals whose interests cover a broad range of diagnostic and therapeutic applications or, more generally, the interaction of sound with biological materials. Exciting new developments in diagnostic ultrasound include innovative contrast agents and “dual-wave” imaging, examples being shear wave elastography, acousto-optic and opto-acoustic imaging. Therapeutic applications are expanding beyond lithotripsy and the treatment of tumors via thermal ablation. Mechanical ablation of soft tissue, known as histotripsy, is an area of active research. Transcranial magnetic resonance guided focused ultrasound is being used for the non-invasive treatment of various brain disorders, including essential tremor, neuropathic pain, and Parkinson’s disease. The ability to temporarily open the blood-brain barrier and deliver chemotherapy to brain tumors using focused ultrasound has been demonstrated in a human for the first time. Researchers are also developing echogenic liposomes and microbubbles for targeted drug and gene delivery using low intensity focused ultrasound. As technology and protocols continue to evolve, developments in biomedical acoustics hold considerable promise towards the advancement of both diagnosis and treatment of debilitating diseases.
The technical committee on musical acoustics: From log drums to synthesizers
Authors: Moore Thomas
Published: May 2016

The Technical Committee on Musical Acoustics is home to researchers interested in the physics of musical instruments, music perception, and the science of the singing voice. Members of the committee typically come to musical acoustics from outside the field; therefore, there are a variety of backgrounds and interests represented. However, musical acousticians are united by a common interest in understanding the science of music. TCMU is an interdisciplinary technical committee with ties to architectural, psychological and physiological, signal processing, speech, physical, and structural acoustics.
The wide world of noise
Authors: Ryherd Erica E.
Published: May 2016

Noise invades all aspects of our lives. The word noise is actually derived from the Latin word “nausea,” with one possible connection being that unpleasant sounds were made by seasick passengers or sailors in ancient times. In modern times, the demand for noise research and consulting has intensified in concert with rising population densities, growing industrialized societies, escalating demands from consumers, and increasingly common standards and legislation related to noise. The Acoustical Society of America Technical Committee on Noise (TC Noise) is concerned with all aspects of noise, ranging from noise generation and propagation, to active and passive methods of controlling noise, to the effects of noise on humans and animals. This talk will explore the broad topic of noise and its impact on our world.
Unexpected pros and cons of planned freeway sound wall removal
Authors: Hale Marlund E.
Published: May 2016

Sound walls are a common occurrence along heavily traveled freeways near sensitive receptor areas. As freeways lanes are increased to handle more traffic, vehicle speeds and traffic noise are prone to increase initially until traffic volumes increase to capacity. Under this scenario, impacted residents can petition for improved mitigation measures. A less common scenario occurs when sensitive receptor areas are abandoned and highway departments are petitioned to remove a freeway sound wall. This situation requires careful analysis and justification to be approved. If there are secondary sensitive receptors that have benefited from the reduced traffic noise due to a sound wall, what potential noise impacts might they experience if the freeway sound wall is removed? Recently, a commercial developer embarked on just such a project. Careful analysis of the proposed project and existing conditions revealed a more complex situation than originally described. Existing reflective sound walls of different heights on either side of the freeway, different near and far sensitive receptor areas behind the sound walls, different jurisdictions, topographical variations, and other competing commercial areas farther along both ends of the sound wall, all added to the project complexity and are discussed along with unintended consequences and unforeseen benefits.
Noise dosimetry of ensemble musicians at Brigham Young University—Idaho
Authors: Blaylock James , Hawks Daxton , Flamm Ryan , Weiss William , Johnson Jon P.
Published: May 2016

Students studying music can be exposed to high levels of sound while practicing, both the sound they create and the sound created by those around them. While playing one’s instrument and creating sound are crucial to a student’s success, the music itself and ambient sound may result in noise-induced hearing loss for the musician. We have made noise dose measurements to investigate the sound that students are exposed to while practicing in a large symphonic ensemble. Contributing factors of high volumes of sound may include students’ instruments, a poorly insulated practice room, practice room resonances and reflection characteristics, and loud instruments being played in other rooms. Further research could include investigation of better insulated practice rooms, or possible rearrangements of musicians’ seating.
The Iterative Nonlinear Contrast Source method: A versatile approach for numerical computation of nonlinear acoustic wave fields
Authors: Verweij Martin D.
Published: May 2016

Acoustic wave propagation is inherently nonlinear because the acoustic field influences the state of the medium. When frequency, amplitude, and propagation distance are sufficiently high, nonlinear effects become significant. Although undesired in many cases, nonlinearity is explicitly employed in medical ultrasound, e.g., by using reflections of the emerging higher harmonics to improve diagnostic image quality. Simulation of novel ultrasound devices and protocols requires the computation of pulsed nonlinear ultrasound fields over three dimensional domains that are typically hundreds of wavelengths in size. The Iterative Nonlinear Contrast Source (INCS) method primarily has been developed for this purpose. It solves the Westervelt equation by considering its nonlinear term as a contrast source that radiates, alongside the primary sources, into a linearized homogeneous background medium. Convolution with the analytical background Green’s function yields the acoustic pressure field of the sources. An increasingly accurate approximation of the nonlinear field is obtained by iteratively substituting the computed field into the nonlinear contrast source. Spatiotemporal filtering allows the four-dimensional convolutions to be performed by FFTs that employ only two points per wavelength. The talk will cover the basic features of INCS, inclusion of attenuation and medium inhomogeneity, presentation of some characteristic results, and possible future extensions.
Three-dimensional vibrations of acoustoelectric superlattice in ferroelectric plate
Authors: Nadtochiy Andriy , Cremaldi Lucien , Ostrovskii Igor
Published: May 2016

The vibrations and matching acousto-electric resonances in 3-D periodically poled LiNbO3 bar are investigated. Two superlattices are fabricated in the z-cut 0.5-mm-thick wafers. They consist of the inversely poled domains of 0.45- or 0.3-mm long along the x-axis and tens-mm wide along the y-axis. Metal electrodes are deposited at the ends of superlattices along the x-axis. Experimentally, the vibrations are excited in MHz frequency range by the electric current along the x-axis or acoustic burst propagating along this axis. The function generator, digital oscilloscope, and spectrum analyzer allow measuring frequency dependencies of the acousto-electric resonances in rf-admittance Y(f), and transmission coefficient for acoustic burst propagating through the superlattice. The finite element method computations yield the acoustic displacements and acousto-electric admittance versus frequency. The displacements have three components along the x, y, and z axes. They are minimized within the stop-bands frequencies, which may vary for different displacement components. The number of resonances in Y(f) occur from 2 to 8 MHz. The spectral positions of resonances correlate with the frequencies of stop-bands boundaries for all three displacement components. The results obtained may be used for development of new applications such as multi-displacement ultrasonic transducers and actuators, acousto-electric filters, and oscillators.
Towards real-time two-dimensional wave propagation for articulatory speech synthesis
Authors: Zappi Victor , Vasudevan Arvind , Fels Sidney
Published: May 2016

The precise simulation of voice production is a challenging task, especially when real-time performances are sought. To fulfill real-time constraints, most articulatory vocal synthesizers have to rely on highly simplified acoustic and anatomical models, based on 1D wave propagation and on the usage of vocal tract area functions. In this work, we present a 2D propagation model, designed to simulate the air flow traveling through the midsagittal contour of the vocal tract. Building on the work by Allen et al. [Andrew Allen and Nikunj Raghuvanshi, “Aerophones in flatland: Interactive wave simulation of wind instruments,” ACM Trans. Graph. 34, Article 134 (2015)], we leverage OpenGL and GPU parallelism for a real-time precise 2D airwave simulation. The domain is divided into cells according to a Finite-Difference Time-Domain scheme and coupled with a self-oscillating two-mass vocal fold model. To investigate the system’s ability to simulate the physiology of the vocal tract and its aerodynamics, two studies are presented. First, we compare the performances in vowel production of our 2D approach with other 1D wave propagation systems in literature, using area functions. Subsequently, this case is extended by replacing area functions with 2D vocal tract contours derived from 3D MRI data.
Detection of longitudinal resonances in brass wind instrument bells
Authors: Moore Thomas , Kausel Wilfried
Published: May 2016

It was shown more than a decade ago that the vibrations of the bells of brass wind instruments can affect the sound produced by the instrument. The effect of damping the vibrations is easily perceived by both the player and the listener, but the change in the sound cannot be attributed to merely eliminating direct radiation from the structure. Recently, it has been shown that coupling between the air column and the longitudinal motion of the bell is partially responsible for this effect, and it is possibly the dominant cause. However, identifying the longitudinal resonances of a flaring circular duct and separating them from the elliptical resonances is challenging. Using a combination of laser Doppler vibrometry and common-mode rejection electronic speckle pattern interferometry allows these modes to be unambiguously identified.
Active control of fluid-loaded vibrations in the mammalian inner ear
Authors: Meaud Julien
Published: May 2016

The mammalian inner ear is a sensory system that converts acoustic signals into electrical signals sent by hair cells to the brain. Hair cells are stimulated by vibrations of cochlear structures that are immersed in cochlear fluids. Normal hearing requires the presence of a nonlinear active feedback mechanism that boosts vibrations of cochlear structures and makes it possible to achieve high sensitivity, high frequency selectivity, and a broad dynamic range. In this talk, I will present the key characteristics of active control of vibration in the mammalian inner ear. I will demonstrate that computational models that take into account the structural acoustics of the inner ear and include realistic models of the active feedback mechanism can help to better understand the active control of vibrations in the inner ear. This understanding could be exploited to design biomimetic sensors and acoustic filters.
Wave propagation through additive manufactured phononic crystals
Authors: Kerrian Peter , Hanford Amanda , Dickman Corey , Capone Dean
Published: May 2016

Obtaining the effective parameters is an important step in designing a unit cell for a variety of metamaterial applications. The effective parameters including the density and bulk modulus govern how a wave propagates through a medium constructed from unit cells. Additive manufacturing has created the potential to change the static density of materials by encapsulating metallic powder inside the produced component. This work will use modal analysis to extract the bulk modulus from additive manufactured rods. After the material properties are determined, numerical and experimental results will be compared for wave propagation through a phononic crystal constructed from additive manufactured rods of different densities.
Informational masking and the effects of differences in fundamental frequency and fundamental-frequency contour on phonetic integration in a formant ensemble
Authors: Summers Robert J. , Roberts Brian , Bailey Peter J.
Published: May 2016

This study explored the effects on intelligibility of across-formant differences in fundamental frequency (ΔF0). Sentence-length speech analogues were presented dichotically (left = F1 + F3; right = F2), either alone or—because competition usually reveals grouping cues most clearly—accompanied in the left ear by a competitor for F2 (F2C) that listeners must reject to optimize recognition. F2C was created by inverting the F2 frequency contour. In experiment 1, all left-ear formants shared the same constant F0 and ΔF0 for F2 was 0 or ±4 semitones. In experiment 2, all left-ear formants shared the natural F0 contour and that for F2 was natural, constant, exaggerated, or inverted. Adding F2C lowered keyword scores, presumably because of informational masking. The results for experiment 1 were complicated by an asymmetry between the ±4 semitone cases; this problem was avoided in experiment 2 because all four F0 contours had the same geometric mean. When the target formants were presented alone, scores were high and did not depend on the F0 contour for F2. F2C impact was greater when F2 had a different F0 contour from the other formants. This was a direct consequence of ΔF0; the F0 contour for F2 per se did not influence competitor impact. [Work supported by ESRC.]
Effects of voice-onset time and talker variability on lexical access
Authors: Lee Jieun , Lee Chao-Yang
Published: May 2016

The effects of voice-onset time (VOT) and talker variability on accessing word meanings were investigated. Two short-term semantic priming experiments were used to evaluate if the magnitude of semantic priming would be reduced by these two types of variability. In experiment 1, a lexical decision task and a phoneme identification task were used to examine whether listeners’ sensitivity to VOT affects their processing of a semantically related word. In experiment 2, a lexical decision task and a talker discrimination task were used to examine whether listeners’ sensitivity to talker changes affects lexical access. The results showed that while listeners were sensitive to VOT and talker variability, neither affected the magnitude of semantic priming. Nonetheless, experiment 2 also showed that talker discrimination was easier when real word targets were presented, indicating that the word/non-word lexical status affected the processing of talker information. These findings, overall, suggest that there is no evidence that VOT and talker variability affect accessing word meanings.
Frequency-dependent beam pattern of acoustic arrays for unmanned aerial vehicle tracking
Authors: Culver R. Lee
Published: May 2016

There are practical constraints on the geometry and construction of acoustic arrays which are designed to detect small unmanned aerial vehicles (UAVs). The constraints depend to a large degree on the environment in which the array must operate. For example, an acoustic array which provides UAV detection to protect a public stadium is likely to differ considerably from one which soldiers can carry into the field and deploy to protect their position. The former can use almost unlimited power, be very large and be composed of many elements, while the latter will probably run on batteries or solar and must be man-portable. These different designs provide different performance as measured by detection range, array gain, and angular resolution, for example. This talk presents the performance of several common array configuration over the band of frequencies in which passive AUV detection at tactically useful ranges is possible.
Noise identification and ongoing research and monitoring for Red Rocks Amphitheatre
Authors: Pyper Ted , Whitney Matt
Published: May 2016

Beginning in 2013, a noise survey was initiated by the famed Red Rocks Amphitheatre, outside Denver, CO, to respond to noise concerns from nearby communities. Complaints focused on excessive bass frequencies originating from the outdoor venue. Some neighbors even complained of physical vibrations in their residences from amplified music over a mile away. The survey was executed to document the level differences between the sources in the venue and the measured levels in the neighborhoods. Vibration levels were also measured, in addition to airborne noise levels, to verify and diagnose the specific spectrum associated with the complaints. Remedial treatments were studied, and policies have been put in place to monitor and control the overall levels within the venue. Ongoing monitoring and research have evolved over the last several years to better address the concerns of neighbors, while preserving the concert experience within the venue.
A reformulation of the ΛΦ diagram for the prediction of ocean acoustic wave propagation regimes
Authors: Colosi John A.
Published: May 2016

The ΛΦ diagram was a tool introduced in the late 1970s to predict ocean acoustic fluctuation regimes termed unsaturated, partially saturated, and fully saturated, where internal wave sound-speed fluctuations play a dominant role. The ΛΦ parameters reflect, respectively, the strength of diffraction and the root mean square phase fluctuation along a ray path. New oceanographic knowledge of the small scale part of the internal wave spectrum, and high angle Fresnel zone formulations now allow a more stable and accurate calculation of these parameters. An empirical relation between the variance of log-intensity and ΛΦ provides a more accurate border between the unsaturated regime and stronger fluctuations. The new diagram is consistent with six short-range, deep-water experiments in the Pacific, Atlantic, and Arctic oceans with frequencies ranging from 75 to 16 000 Hz. The utility of the ΛΦ diagram is that it provides one of the few means to inter-compare experiments at different geographic locations, different frequencies, and ranges.
Potential biomedical applications of non-dissipative acoustic radiation force
Authors: Sarvazyan Armen , Tsyuryupa Sergey
Published: May 2016

Acoustic radiation force (ARF) has been used for many medical applications, the most notable of which is measuring the stiffness of soft tissues. The ARF used in these applications results from the dissipation of acoustic energy due to scattering and absorption of sound and accordingly may be called dissipative ARF. Another source of ARF, which is not related to dissipation of acoustic energy in medium, is variation in acoustic energy density due to gradients of compressional wave speeds in the medium. The effects of this non-dissipative ARF (nARF) are most pronounced in sonication of medium by short ultrasonic pulses with duration on the order of microseconds. Experiments with tissue-mimicking gelatin blocks and various excised animal tissues demonstrated the possibility of measuring sub-nanometer range displacements induced by nARF acting on interfaces in materials with different compressional wave speeds. A continuous wave Doppler device was used to measure the interface particles velocity. Demonstrated possibility of using Doppler signal processing to extract the nanometer-order motion induced by the nARF could open new areas for ultrasound imaging and tissue characterization. The creation of multi-parametric images of soft tissue using nARF for obtaining maps of the compressional wave speed and shear modulus is considered.
Effects of acoustic parameters on nanodroplet vaporization
Authors: Kumar Krishna N. , Aliabouzar Mitra , Sarkar Kausik
Published: May 2016

Phase shift nanodroplets offer a number of advantages over ordinary microbubbles due to their enhanced stability and smaller size distribution. These nanodroplets undergo a phase transition from liquid to highly echogenic gaseous state when activated by sufficient acoustic energy through a process termed acoustic droplet vaporization (ADV). In this study, we synthesized lipid-coated perfluoropentane (PFP) filled nanodroplets via sonication method. We investigated the ADV threshold of these nanodroplets as a function of acoustic parameters such as excitation pressure, frequency, pulse length, and pulse repetition period (PRP). Our results indicate that ADV threshold varies significantly with PRP; while at PRP of 10 ms, the ADV threshold was found to be 3.6 MPa (pk-pk), for PRP of 1 ms, 100 μs, and 500 μs, ADV was not observed even at 10 MPa. At ADV, fundamental and odd harmonics were found to be significantly higher than the background noise. The acoustic response of ordinary perfluorobutane (PFB) filled microbubbles with the same lipid composition is compared to that of PFP nanodroplets when both were excited with the same excitation pressures (450 kPa to 10 MPa). Above ADV threshold both showed a similar response.
Lytic efficacy of tissue plasminogen activator and ultrasound in porcine clots doped with barium sulfate in vitro
Authors: Huang Shenwen , Shekhar Himanshu , Holland Christy
Published: May 2016

Swine and porcine tissue are employed routinely for preclinical models of ischemic stroke. In this study, we examined the lytic susceptibility of porcine whole-blood clots, prepared with and without barium sulfate, a radiopaque x-ray contrast agent. The degree of lytic efficacy in the two types of clots was compared for recombinant tissue plasminogen activator (rt-PA) concentrations ranging from 0 to 100 μg/mL. Subsequently, a in vitro flow model and time-lapse thrombolysis microscopy system was used to evaluate lysis in clots with and without barium sulfate in response to rt-PA and 120-kHz intermittent ultrasound exposure. The degree of lysis observed with both types of clots was similar for rt-PA concentrations up to 15.75 μg/mL. However, clots doped with barium sulfate demonstrated significantly lower lysis at higher rt-PA concentrations. Similarly, results obtained using the in vitro flow model showed that both types of clots underwent comparable lysis when treated with 15.75 μg/mL rt-PA. Further, using Definity® and 120-kHz ultrasound as an adjuvant to rt-PA did not enhance lysis in either porcine clot model compared to rt-PA alone. These results highlight the considerable differences in the degree of clot lysis between porcine clots and previously reported studies that used human clots.
Study of virtual instrument technology applied in sound field test
Authors: Yao Yongchao , Ju Xiaodong , Lu Junqiang , Men Baiyong
Published: May 2016

As a widely used technology in the field of test and measurement, virtual instrument (VI) combines high-performance modular hardware with flexible software to perform a variety of experimental tasks. In order to perform the sound field test in laboratory, we build an specialized platform of VI, whose hardware system mainly consists of multi-channel data acquisition boards, independence analyzer, mechanical positioning device, and industrial personal computer equipped with PXI, GPIB, and Ethernet bus interface. Also, a graphical VI programming language (LabVIEW) is adopted to develop the corresponding software system. With this VI platform, we measure the impedance property of transducers and the sound field of a phased array composed of them. The results show that the transducers are positioned correctly by the mechanical positioning device, the excitation time of every transducer of the phased array is controlled accurately, and finally a set of high-quality waveforms are acquired.