bluuebunny/crossref_metadata_2025 huggingface dataset:
Steps towards promoting bioacoustics research in Mexico
Authors: Vivas Eduardo
Published: October 2015

Bioacoustics has played a major role in animal research in the past decade. Unfortunately, in Mexico, it is still seen as a novel approach, and few research groups incorporate it into their studies. To overcome this lag, work needs to be done in three major areas: Collaboration among experts, preparing young students, and providing specialized equipment. In Mexico, there are many institutions devoted to research in biology, but there are only a few researchers in acoustics because there are no graduate research programs in this area. Collaboration among acousticians interested in biology and biologists interested in acoustics becomes crucial, and future researchers, coming from both specialties, need to be prepared. Once this synergy is created, emerging research groups often see the cost and availability of specialized equipment as a limitation, so it is also necessary to focus on providing access to research-grade, low-cost hardware. In this talk, I will describe my efforts toward promoting bioacoustics research in Mexico through collaboration with other research centers, with examples of ongoing projects, graduate program support, and equipment presented in major peer-reviewed conferences that we have developed with low-cost, open source materials that are comparable with standard, high quality research equipment.
Bioacoustic characterization of a coastal marine soundscape in Quintana Roo, Mexico
Authors: Spence Heather R. , Houser Dorian S.
Published: October 2015

Wild dolphins are exposed to a variety of biological and other natural and anthropogenic sounds. Several species of dolphins, including bottlenose dolphins (Tursiops truncatus), have been documented in the MesoAmerican Reef (MAR) region; however, there is little to no scientific monitoring of these populations. Characterizing the soundscape of wild dolphins on a section of the MAR would facilitate understanding the acoustic nature of this dolphin habitat. Passive Acoustic Monitoring using an Ecological Acoustic Recorder was conducted for one year off the coast of Quintana Roo, Mexico, just north of Isla Mujeres, a site where dolphins are known to be frequent. The soundscape was typified by natural sounds, however there was important periodic contribution by anthropogenic sources. Boat motor noise contributed to higher SPLrms during the day than in the night and contributed to noise between 500 Hz and 25 kHz, which is consistent with small vessels. While boat motor noise was not as frequent as fish sounds nor as pervasive as snapping shrimp sounds, when present it potentially overwhelms the natural soundscape. Anthropogenic characteristics of this soundscape have implications for dolphin welfare and regulations in the nearby marine protected areas.
Assessing the structure of a Neotropical bat community using acoustic monitoring techniques
Authors: Estrada Villegas Sergio , Meyer Christoph F. , McGill Brian , Kalko Elisabeth K.
Published: October 2015

Determining the structure and composition of tropical communities is challenging because some species are rare or hard to detect. Within Neotropical bats, aerial insectivores have been systematically undersampled because they avoid mist nets, the traditional sampling tool. Advances in bioacoustic monitoring techniques have allowed the study aerial insectivorous bat (AIB) communities across various spatial scales and habitats. We present two studies that assessed the underlying mechanisms that structure an AIB community across the Isthmus of Panama. First, we evaluated how habitat fragmentation affected two guilds of AIBs and found higher species richness in islands than in continuous forests. Background clutter aerial insectivores showed compositional differences due to effects of isolation, area, and forest complexity, whereas open space bats were not affected by fragmentation. Second, we determined how climate and forest complexity affected AIB community structure at different spatial scales. We found that most of the variation in bat richness, abundance, and feeding activity occurred at the smallest spatial scale (10×10m) and was explained by habitat structure. In contrast, at large scales, climatic differences explained most of the variation in individual species’ abundances. Interestingly, species richness peaked at intermediate levels of precipitation, while total abundance was very similar across sites.
Scaled mining of environmental acoustic data from temperate to tropical forests, from ocean to tropical rivers: A convolutional feature learning approach
Authors: Glotin Herve
Published: October 2015

Scaled passive acoustic monitoring has recently been developed to assess changes in biodiversity. It is applied to monitor changes in fauna composition associated with anthropogenic impacts and to improve the management of species and habitat conservation. Under the auspices of the “Scaled Acoustic BIODiversity” SABIOD project (CNRS MI/GDR MADICS/JASON UTLN), interdisciplinary teams collaborate to develop new joint machine learning and signal processing bioacoustic analyses. Currently, terabytes of sounds are recorded monthly using the innovative open SABIOD autonomous sensor arrays, positioned within forests or deep in the ocean. The challenges associated with tropical biodiversity as the variety of sound sources and the complexity of acoustic paths are being addressed by optimizing strategies that couple features learning, convolutional neural net, and advanced passive acoustic localization/filtering. Applications are many, including the classification of one thousand Amazon bird species, whale song classification, automatic indexing forest soundscapes, passive acoustic 3D tracking of bats and cetaceans with our patented system, and offshore cetacean monitoring. We discuss the main difficulties encountered and summarize the promising steps and strategies that we intend to pursue in the future coupling scaled CNN with Deep Scattering Spectrum. Demo/details: http://sabiod.univ-tln.fr.
Simulation of wave propagation in anisotropic and viscoelastic tissues
Authors: Urban Matthew W. , Qiang Bo , Aristizabal Sara , Nenadic Ivan , Song Pengfei , Chen Shigao , McGough Robert J. , Greenleaf James F.
Published: October 2015

Many methods for characterization of the mechanical properties of soft tissues using propagating shear waves have been developed over the past two decades. Most of these methods assume that the shear wave is traveling in an elastic, isotropic tissue. However, many soft tissues are viscoelastic and have material properties that are directionally dependent or anisotropic. We have been developing methods to measure waves propagating in soft tissues to estimate the anisotropic viscoelastic material properties. To refine our measurement methods, we have also developed techniques and models for simulating the wave propagation in these types of materials. We have developed specialized finite element and pseudo-spectral models that can simulate viscoelastic transversely isotropic materials and compared our results with measurements in ex vivo porcine muscle. Additionally, we have developed a finite element model that simulates wave propagation in the myocardium by creating a model of layered transverse isotropic media oriented at different angles. We examined the effect of frequency of the waves for estimating of the angle of propagation. We compared these simulation results with experimental results from an ex vivo porcine left ventricular wall. These simulation methods provide insight for optimizing our measurement methods for in vivo characterization of material properties.
Numerical simulation of transcranial focused ultrasound therapy
Authors: Pulkkinen Aki T. , Werner Beat , Martin Ernst , Hynynen Kullervo
Published: October 2015

Transcranial focused ultrasound therapy is becoming a viable tool for treatment of brain related disorders. The technique has been used for treatment of essential tremors and chronic neuropathic pain with good results. In addition, the technique has a broad scope of potential applications including: tumor ablation, localized drug delivery, thrombolysis, and neurostimulation. Performing an efficient focused ultrasound treatment delivery requires planning. Accurate computational models could, in principle, be utilized to provide auxiliary guidelines for such planning. In this work, a computational model is presented for simulating the propagation of ultrasound in transcranial setting. The effects of ultrasound propagation through soft tissue and bone are modeled by coupling wave equations of fluid and solid. The coupled model is numerically evaluated by using a hybrid simulation technique that couples finite difference method with a grid method. The resulting computational model is utilized to simulate focused ultrasound field in clinical patient treatment setting. Effect of absorption of heat into the brain tissue is further simulated by using the bioheat equation. Simulation results are compared with magnetic resonance thermometry performed during the clinical treatments for evaluation of validity of the computational model.
Viscosity-compensated shear speed imaging with acoustic radiation force
Authors: Yang Yiqun , Urban Matthew W. , McGough Robert J.
Published: October 2015

Shear wave elastography imaging (SWEI) with ultrasound uses an applied acoustic radiation force to obtain quantitative images of liver, breast, prostate, and other soft tissues. In SWEI, shear velocity waveforms are collected along a line, and then, the shear speed is estimated either with a k-space or a correlation-based method. Although these yield effective estimates in elastic media, both methods consistently overestimate the shear speed in viscoelastic soft tissue because neither considers the shear viscosity. To address this problem, we have created a new shear speed estimation approach that also accounts for the effect of shear viscosity. The new approach is evaluated in a computational model that calculates the three-dimensional (3D) intensity field generated by a linear array transducer in FOCUS (http://www.egr.msu.edu/~fultras-web) and then simulates the shear wave velocities in a viscoelastic medium with a 3D finite difference model. In the viscoelastic shear wave simulation model, the shear speed constant is 1.5 m/s, and the shear viscosity is 1 Pa·s. Correlation-based shear speed estimates are compared to the viscosity-compensated estimates, and the results show that the viscosity-compensated approach consistently achieves improved shear speed estimates relative to the correlation-based method. [Work supported in part by NIH Grant Nos. R01EB012079 and R01DK092255.]
Acoustic fields and ultrasound contrast agents
Authors: Allen John S.
Published: October 2015

Ultrasound contrast agents are encapsulated gas bubbles which oscillate nonlinearly upon acoustic excitation. Recent developments include targeted agents for molecular imaging applications and ultrasound contrast agents such those with polymer shells specifically designed for high frequency ultrasound applications. Though a variety of models have been proposed since the early development of the agents, many outstanding questions exist on the specifications of the shell and most appropriate model for the different materials. Moreover, only recently have independent mechanical measurements been attempted to advance and facilitate modeling efforts. The various shell models are reviewed and discussed. Validation of models of polymer shell agents are given with respect high frequency acoustic microscopy quantification of the shell elastic properties. Recent work on the modeling and design of agents for high frequency subharmonic excitation based on adaptive signal processing and nonlinear time series methodologies is overviewed. Novel analytical method for treating hydrodynamic interactions with respect to unsteady drag and secondary acoustic radiation forces are outlined with respect to drug delivery and sonoporation applications. The direction and magnitude of coupled oscillations are investigated with respect evolution of the amplitude and phase and the transfer entropy.
Myocardial cavitation-enabled therapy modeling
Authors: Zhu Yiying I. , Miller Douglas L. , Kripfgans Oliver D.
Published: October 2015

A therapeutic method named Myocardial Cavitation Enabled Therapy aiming at noninvasive cardiac tissue reduction is modeled here. Sparsely distributed microlesions induced by ultrasound cavitation of contrast agents are hypothesized to cause myocardial shrinkage. The objective is to model lesion formation based on the acoustic field and plan treatments accordingly. An ultrasound field simulation was established in Field II, an acoustics toolbox. It simulates the acoustic field of a 1.5 MHz ultrasound burst of five cycles at 4.0 MPa peak rarefactional pressure amplitude (PRPA) by use of a F# 2 single element therapeutic transducer, as used in concomitant animal studies. Medium parameters, including speed of sound, density, absorption, and B/A were set to water path and heart tissue along the acoustic path. Lesions were masked as region exceeding 2 MPa PRPA, the threshold of microlesions occurrence. The lesion volume is 143 μL compared to in vivo rodent study of approximately 100 μL. To reach a larger lesion in pigs, sweeping of the ultrasound beam is needed using a phased array. Nonlinear acoustic simulation from k-Wave software will assist transitioning from single element to imaging array apertures in terms of interpreting possibly different lesion formation resulting from nonlinearities.
Air resonance power efficiency evolved in the violin and its ancestors
Authors: Nia Hadi T. , Jain Ankita D. , Liu Yuming , Alam Mohammad-Reza , Barnas Roman , Makris Nicholas C.
Published: October 2015

Acoustic radiation from a violin can be explained by clear physics at its lowest frequency resonance (air resonance), which also helps to explain key aspects of violin design evolution. It is found that inefficient, inactive void area was decimated and air-resonance power doubled as sound-hole geometry of the violin's ancestors slowly evolved over eight centuries from simple circles of Medieval 10th century fitheles to complex f-holes of the late Renaissance and Baroque period. F-hole length then increased across centuries in the renowned Amati, Stradivari, and Guarneri workshops, favoring correspondingly higher air-resonance power, by processes consistent with random craftsmanship mutations and subsequent selection.
Acoustical evolution of the viola da gamba
Authors: Campbell D. Murray , Campbell J. Patricia , Woodhouse Jim
Published: October 2015

The viola da gamba (or viol) emerged as a distinctive type of bowed string instrument during the fifteenth century. Its characteristics include a fingerboard with gut frets and between five and seven strings tuned in fourths with a central major third. By the end of the fifteenth century, the instrument was being constructed in a range of sizes. To investigate the acoustical significance of design changes during the evolution of the viol family in the sixteenth and seventeenth centuries admittance measurements at the bridge have been made on a wide variety of reproductions of viols and other early bowed-string instruments. A comparison of the results with existing data on modern violin-family instruments, and other stringed instruments such as guitars, reveals that the acoustic behavior of viols is more disparate than that of violins or guitars. Models that have been measured include examples with and without a soundpost, and a correspondingly wide range of frequency responses is seen. The influence of the viol bridge and the significance of the adoption of overwound bass strings are also discussed.
Evolution of the piano
Authors: Giordano Nicholas
Published: October 2015

The first pianos were built around 1700 and unlike the case with many other instruments, we know precisely what the first pianos were like since several of them still exist. These early pianos were patterned after Italian harpsichords of the time, with the plucking mechanism of the harpsichord replaced by an “action” mechanism that enabled hammers to strike the strings. The first pianos had a compass of four octaves with brass and iron strings, and a frame composed of wood. The design of those instruments along with the various stages of their evolution into the modern piano with its 88 notes, steel strings and a cast iron plate will be described. The manner in which this evolution was driven by the needs of composers and musicians along with advances in technology will also be discussed.
A proposed test of some people's ability to sense wind turbines without hearing or seeing them
Authors: Schomer Paul D.
Published: October 2015

Around the world, there are people that allege they sense times when significant power is being generated by a turbine from when little to no power is being generated. In contrast, the American Wind Energy Association (AWEA) and its Canadian counterpart (CanWEA) maintain that this is not possible, without these people hearing the turbines or seeing them move. A simple test can quickly clarify these opposing views. Notionally, people who live in residences situated beyond the threshold of hearing (indoors) would be tested in the area that they can sense the wind turbines. They would be told to tell the proctor when they sensed the turbine at power. They would be told the turbine might or might not be turned on in the next X hours. The area of the house they were in would have to be free of any visible or audible clues. No communication would be permitted between the subject and the outside world. The proctor also would not know when or if the turbine would come on. These and other controls like these would make for a quick, simple, unbiased test of some people’s ability to sense wind turbines without hearing or seeing them.
Modeling of fighter jet cockpit noise
Authors: Wall Alan T. , Gallagher Hilary L. , McKinley Richard L.
Published: October 2015

Military fighter jet cockpit noise may pose a hearing loss risk to pilots and can disrupt communications. The current study is an attempt to model the noise levels in the cockpit of F-35 aircraft as a function of aircraft operation parameters. Levels are based on a complex interplay of parameters such as airspeed, altitude, dynamic pressure, and the flow rate of the in-cockpit environmental control system. Full population of an operational envelope from point-by-point measurements would require an excessive number of flights. In the current work, in-cockpit noise levels were measured during sampled flight conditions. Correlations between levels and flight parameters were investigated. A preliminary parameter-based model is presented, and the ability to predict levels within the operational flight envelope is addressed. [Work supported by USAFRL through ORISE.]
Jet noise of high-performance aircraft at afterburner
Authors: Tam Christopher
Published: October 2015

The jet noise from a high-performance aircraft at afterburner is investigated. The main objective is to determine whether the dominant noise components are the same or similar to those of a hot supersonic laboratory jet. For this purpose, measured noise data from F-22A Raptors are analyzed. It is found, based on both spectral and directivity data, that there is a new dominant noise component in addition to the usual turbulent mixing noise. The characteristic features of the new noise component are identified. Measured data indicates that the new noise component is observed only when the rate of fuel burn of the engine is increased significantly above that of the intermediate power setting. This suggests that the new noise component is combustion related. The possibility that it is indirect combustion noise generated by the passage of hot spots from the afterburner through the nozzle of the jet is investigated.
The perception of vocal-tract length in cochlear implant users: Can it be improved?
Authors: Gaudrain Etienne , El Boghdady Nawal , Başkent Deniz
Published: October 2015

When trying to understand a speaker among competing speakers, normal-hearing listeners take advantage of differences in the voices of the talkers. However, cochlear implant (CI) users do not seem to benefit from such voice differences. Roy D. Patterson's group in Cambridge has applied psychophysical methods to voice perception in order to isolate the acoustic cues that allow listeners to identify and segregate voices [e.g. Smith, Patterson, Turner, Kawahara and Irino, 2005, J. Acoust. Soc. Am., vol. 117, pp. 305–318]. In our group, we have extended these methods to CI listeners to fully characterize the limitations CI users experience in utilizing voice characteristics. More specifically, we have shown that while voice pitch (F0) is sufficiently salient through the implant to allow gender categorization, the perception of vocal-tract length (VTL) is severely degraded, leading to erroneous gender perception. With the help of acoustic simulations mimicking the CI processing, the potential factors explaining this lack of sensitivity for VTL were explored. Poor spectral resolution, spectral quantization, and spectral distortion were all found to affect VTL just-noticeable-differences. These results have yielded a number of potential solutions to improve VTL representation — and hence concurrent speech perception — in the implant.
Probing monaural edge pitch
Authors: Hartmann William M. , Li Xiaochen , Cariani Peter
Published: October 2015

Noise with a sharp spectral edge, occurring at an edge frequency fe, leads to a tonal sensation with a timbre like that of a sine tone and a pitch near the edge frequency. For lowpass noise the pitch is shifted below fe and for high pass noise the pitch is shifted above. Typical shifts are less than 10% of the edge frequency. To probe this effect, pitch matching experiments were done using 32 different lowpass and highpass noises with edges at 500 and 600 Hz and with durations of about 50 ms. Pitch matches were made in an indefinitely repeating cycle of noises and half-second matching tones. After each match, listeners rated the difficulty of the match. The ratings were ultimately reduced to a five-point scale. The experimental data were compared with the predictions of a model based on the peaks of an all-order population interval distribution as determined by the Zilany-Bruce-Carney model of the auditory periphery. Matching frequencies were predicted from the periodicities of the best fitting subharmonic template and matching difficulty was predicted by the relative goodness of fit. Correlations between experiment and prediction were often high, approaching 0.9. [Work supported by the USAFOSR].
Acoustic and auditory sketches: Recognition of severely simplified natural sounds by human listeners
Authors: Isnard Vincent , Taffou Marine , Viaud-Delmon Isabelle , Suied Clara
Published: October 2015

Sounds in our environment like voices, animal calls, or musical instruments can be recognized on the basis of timbre alone. The objective of this study was to unravel the features underlying this robust sound recognition. We investigated how severely sounds can be simplified while still being recognizable. A large number of natural sounds were simplified into “auditory or acoustic sketches:” energy peaks were selected on the auditory or acoustic spectrogram, at three levels of simplification (high, medium, and low). The remaining non-sparse information was removed. Listeners were asked to classify the simplified sounds into their four original categories: instruments, birds, vehicles, or voices. We adapted a recent signal detection model to dissociate the perceptual sensitivity (d' scores) from the bias, for each category (4-AFC task). Overall, severely simplified sounds could still be recognized above chance by the listeners. Auditory distances, based on spectro-temporal excitation patterns (STEPs), were then computed. Participants' performances on the 4-AFC task were well correlated with the auditory distances between the four categories. Altogether, our results suggest that sound recognition is a very robust perceptual process, and that basic spectral and spectro-temporal differences between sounds, captured by the auditory distances, can account for this robust recognition.
Neuromagnetic correlates of the vocal characteristics of vowels in auditory cortex
Authors: Patterson Roy D. , Andermann Martin , Uppenkamp Stefan , Rupp André
Published: October 2015

As a child grows up, the formants of their vowels move down in frequency and the spacing of the harmonics, which determines voice pitch, decreases. Perceptually, these variables determine who we hear speaking (child, woman, or man). In a logarithmic-frequency spectrum, the envelope with its formant peaks moves toward the origin as a unit, without changing shape, as a child grows up. Similarly, the harmonics, which constitute the fine structure of the spectrum, move toward the origin as a unit without changing shape, but at a different rate. This paper describes neuromagnetic studies which show that the generator associated with voice pitch is in Heschl’s gyrus just lateral to primary auditory cortex, while the generator associated spectral envelope position is in planum temporale, some distance behind the pitch activity generator. The posterior generator is close to the location of the large N1m that typically accompanies the onset of acoustic energy of any sort. The pitch processing component of the N1m was isolated from the energy-onset component by presenting sequences of vowels with minimal inter-vowel intervals; the pitch component appears isolated in the responses to the second and succeeding vowels.
Incidental absolute pitch learning in an interactive multi-modal environment
Authors: Heald Shannon L. , Van Hedger Stephen C. , Nusbaum Howard C.
Published: October 2015

Absolute pitch (AP), the ability to label an isolated note without the aid of a reference note, is to some degree trainable in an adult population. Most training studies ask participants to make overt categorization judgments and provide explicit feedback. Here, we examined the incidental learning of four isolated notes in an interactive multi-modal environment. Participants played a video game, whereby four characters, requiring different actions, were marked by specific note classes. Half of the participants experienced an invariant mapping, such that the same perfectly in-tune note always marked each character. The other half experienced a variant mapping, where a distribution of notes that varied in intonation marked each character (the mode of which was an in-tune note). While participants could anticipate a character via its associated note class, such anticipation was not required or encouraged. In a follow-up task, participants matched the characters to their associated notes. Results showed significant rote learning for the character-note pairings with above-chance generalization to novel timbres and octaves. The variant condition mitigated the performance gap found between those with and without video game experience in the invariant condition. Results will be discussed in terms of the mechanisms involved in implicitly acquiring AP categories.
Investigation of hysteresis friction in elements under complex stress state
Authors: Vladimir Smirnov , Tsukernikov Ilya , Shubin Igor , Umniakova Nina
Published: October 2015

Recent studies have indicated that the best type of damping in vibration isolation system is hysteresis (internal) damping, which effectively reduces vibration amplitudes at resonance, and it does not increase as compared with viscous damping vibration amplitudes after the resonance. Modern damping investigation methods are based on the experimental determination of the loss factor for a certain form of vibration isolators with fixed dimensions and loading parameters. At the same time, with the emergence of complex nonlinear vibration isolators, such as discussed by the authors, there is a task of expanding this theory on the case of complex designed vibration isolators. In this paper, we consider the problem of calculating the loss factor in the beam—columns of variable cross-section under complex loading conditions. A method for calculating the amount of losses in the nonlinear vibration isolators is based on Panovko's energy theory, which consists of experimental loss factor determination in the material of the vibration isolator and subsequent calculation of the loss factor in the isolator in view of obtained data.
How speaker identity interacts with perceptual judgments in children with residual sound errors
Authors: Hamilton Sarah , Boyce Suzanne E. , Silbert Noah , Mosko Kirsten
Published: October 2015

Recent research suggests that listeners store complex phonetic representations when learning speech. Encoding fine perceptual details, such as indexical features of the talker’s voice, appears to influence performance in a variety of ways (e.g., processing speed and intelligibility of words in noise). Children with residual sound errors (RSE) for /r/ have been shown to have difficulty judging productions of /r/ from other child speakers along a normalized continuum of third formant values. We hypothesized that children with RSE may make more accurate judgments if they are given stimuli with more familiar indexical characteristics (i.e., their own speech) along the same continuum. In this study, we presented 15 children with a range of stimuli recorded from their own productions as well as productions from other children. In a forced-choice task, children indicated if the word contained a “correct” /r/. Responses to stimuli were compared across children. Initial results suggest that for RSE children, hearing one’s own speech does not improve accuracy in judging the correctness of sounds in words.
The differential development of vowel context effects on sibilant fricatives
Authors: Reidy Patrick
Published: October 2015

Previous work has found that vowel-context effects on the static acoustic properties of sibilant fricatives weaken as children age. The current study extended this prior work by analyzing the development of context effects on the spectral dynamics of English sibilants. Native adults and children (2 through 5 years old) produced /s, ʃ/ in a range of pre-vocalic contexts (/i, e, ɑ, o, u/). Effects of vowel rounding and vowel height were investigated through two pyschoacoustic measures computed from auditory spectra: peak ERB number and excitation drop (difference between maximum high-band and minimum low-band excitation). These measures were estimated from 17 20-ms windows spaced evenly across each production. Effects of vowel context on the intercept and shape of the resulting 17-point trajectories were analyzed with polynomial growth-curve models. Context effects were found to differentially weaken or strengthen in children depending on whether it was the intercept or the shape of the trajectory that was affected. For both sibilants, rounding and height effects on the peak-ERB and excitation-drop intercepts generally weakened with age; whereas, height effects on the shape factors of both trajectories tended to strengthen with age. Future work will extend the analysis to Japanese /s, ɕ/.
Using vowel trajectories for southern U.S. monophthongization
Authors: Reed Paul E.
Published: October 2015

It is widely known that monophthongization of the diphthong /ɑɪ/ is a feature of Southern U.S. English (e.g., Labov, Ash, and Boberg 2006). However, most studies of this phenomenon only use two measurement points, one from the onset and one from the glide, typically around 25% and 75% of the token's duration. While informative about whether or not a particular vocoid is monophthongal, this type of measure does not permit distinguishing among differing types of monophthongal realizations. Research including varieties from the Southern US (cf. Thomas 2000) has found that the trajectory of the vocoid can differentiate social groups. In this investigation, I track the monophthongal realizations from 24 speakers (12 men, 12 women) from Northeast Tennessee, balanced for age and education. I measure each token at 10ms intervals for both F1 and F2 for the entire vocalic duration. Plotting these measures allows for visualization and comparison of the entire trajectory of the articulation. In preliminary work in this population, flatter trajectories inversely correlate with social factors such as age, education, and local attachment. More finely nuanced measures, such as the whole vocalic trajectory, can capture social variation that may be lost when only comparing a few measurement points.
Wind farm infrasound—Are we measuring what is actually there or something else?
Authors: Cooper Steven E.
Published: October 2015

In the olden days of acoustics (pre digital), low frequency analysis used analog narrow band filters and cathode ray oscilloscopes for special problems leading to the general use of peak values. Analog filters have time constants that can affect the derived rms values requiring caution where high crest factors are involved. Modern narrowband digital analysis is based on a FFT of the time signal to extract the periodic function that occurs in the time domain that are then displayed as discrete peaks in the frequency domain. FFT analysis of turbines show discrete infrasound peaks at multiples of the blade pass frequency in addition to sidebands in the low frequency range spaced at multiples of the blade pass frequency. Are these signals actually there or are they a product of modern day analysis. Is the infrasound signature a clue to a different area of investigation? The paper will show the results of testing to compare old fashioned and modern day analysis.
Three-dimensional inversion technique in ocean and seabed acoustics using the parabolic equation method
Authors: Roa Camilo C. , Frisk George V.
Published: October 2015

A three-dimensional parabolic equation (PE) and perturbation approach is used to invert for the range-dependent geoacoustic characteristics of the seabed. The model assumes that the sound speed profile is the superposition of a known range-independent profile and an unknown depth and range-dependent perturbation. Using a Green’s function approach, the total measured pressure field in the water column is decomposed into a background field, which is due to the range-independent profile, and a scattered field, which is due to the range-dependent perturbation. When the Born approximation is applied to the resulting integral equation, it can be solved for the range-dependent profile using linear inverse theory. For simplicity, the sound speed profile in the water column is assumed to be known, and the range-dependent perturbation is added to the index of refraction n(x,y,z), rather than the sound speed profile c(x,y,z). The method is implemented in both Cartesian (x,y,z) and cylindrical (r,θ,z) coordinates with the forward propagation of the field in x and r, respectively. Synthetic and experimental data are used to demonstrate the validity of the method. Keywords: Three-dimensional parabolic equation method, geoacoustic inversion, range-dependent sound speed profile, linear inversion, Born approximation, and Green’s functions.
Analytical discussion of past measurements of acoustic attenuation in mud sediments and of possible future experimental approaches
Authors: Pierce Allan D. , Siegmann William L. , Brown Elisabeth
Published: October 2015

Attenuation of compressional waves in mud is higher than in sea water, and less than in sandy/silty sediments. For experiments reported in 1964 (Acustica) by Wood and Weston, the Inferred circumstances are a 1 m thick mud slab overlying a gravel bottom, with air above (low tide), and with source and receiver either at the mud-gravel interface or slightly above it. Frequencies from 4 kHz to 72 kHz were transmitted, with signals received at a succession of horizontal distances of up to 50 m. Reported data in decibels versus range show considerable erratic behavior. Attempt is made to explain this behavior using a full-wave analysis of a Pekeris waveguide, with a fluid layer (the mud slab) overlying a (fluid or elastic) half-space, with a series of plausible guesses concerning the properties of the half-space. The conclusion is that the data and the circumstances allowed considerable variability in the attenuation estimates, but those made by Wood and Weston were about as good as could be expected. it is argued that placing source and receiver near the interface was a relatively poor choice, and that future experiments of this general type might give better results with the use of vertical arrays.
Measurements and modeling of the variability in normally incident reflections from the seabed
Authors: Bardewa Saroj , Siderius Martin
Published: October 2015

Normal incidence reflection measurements taken during the TREX13 experiment off the coast of Florida show substantial variability. One likely source of variability is due to scattering from the rough surface of the seabed. These data were taken from an omnidirectional source at a relatively low frequency (around 3 kHz). Systems being considered for measuring seabed properties (such as sound speed, density, and roughness) may use commercial echo-sounders that are directional and operate at much higher frequencies. Measurements from the TREX13 data as well as higher frequency systems are analyzed together with modeling to determine how surface roughness effects these measurements. The modeling uses an integral equation approach with a power law roughness spectrum to calculate backscattering of incident plane waves. The effects of changing the model parameters such as seabed type and roughness on the nature of backscattering are examined. The simulated results are compared with the measurements obtained from the experiments. The measurements are further used to calculate the statistical parameters to understand the nature of the normal reflection from a rough seabed.
An experimental modal analysis on the coimbra model of the Portuguese guitar
Authors: Inácio Octávio , Ribeiro Rui
Published: October 2015

The most distinctive Portuguese traditional music style is Fado. In this form of Portuguese music, a singer is accompanied by two instruments: a classical guitar and a pear shaped plucked chordophone with six courses of double strings—the Portuguese guitar. There are two distinct types of this instrument—the Lisbon and the Coimbra models—named after the towns where the two different styles of Fado have developed. These guitars differ basically on their size and tuning, both comprising 6 orders of double steel strings, while the construction method (strutting patterns, wood species used, and soundboard thickness distribution) vary for different builders. As part of an ongoing research project that investigates the vibroacoustical behavior of this instrument for different types of designs, an experimental modal analysis of a fully assembled Coimbra guitar was performed. In this work, we present the results of this analysis showing the main characteristics of the frequency response curves and significant vibratory modes as compared to other similar plucked-string instruments.
Timbre aspects of ride cymbals: Sound coloration analysis using psychoacoustics models and subjective evaluation
Authors: Werner Kauê , Vergara Erasmo F. , Paul Stephan , Cordioli Júlio A.
Published: October 2015

The timbre of a musical instrument is a multidimensional variable that relies on the complexity of human perception. So far, there are only a few studies concerning the timbre of percussion instruments. The sound characteristics of cymbals depend on geometry, material, ways of playing, and so on. On the perceptive side, sound coloration is one of the dimensions most used by musicians with regard to compare the timbre of Ride Cymbals. In order to get insight into the perception of the sound of Ride Cymbals, subjective evaluations of recorded cymbal sounds were carried out, using bipolar rating scales. Psychoacoustic models, such as Sharpness and Tonality, were also used to analyze the sound signals. Based on subjective and objective evaluations, linear regression models were proposed to quantify perceptive dimensions such as brightness and darkness. The coefficients of determination indicate that this kind of model can be used as a feasible way to represent sound coloration in Ride Cymbals.
Modeling of acoustic resonators and resonator arrays with non-ideal geometries
Authors: Calton Matthew F. , Sommerfeldt Scott D.
Published: October 2015

Acoustic resonators offer stable, cost-effective attenuation for many noise control applications. Due to their widespread use in engineering and physics, analytical expressions with varying degrees of accuracy have been obtained to predict performance. However, most of the existing formulations are limited to ideal geometries with sharp transitions between two regions. Practical applications of these acoustic resonators often involve space limitations that necessitate curved segments and gradual transitions. This research aims to better characterize the response of non-ideal geometry acoustic resonators. Using currently available expressions for duct bends, the acoustic impedance of bends with various angles and lengths is determined, in an effort to develop relatively simple models for incorporating such elements in a resonator. Other non-ideal geometries as they relate to Helmholtz resonators and arrays of resonators are also explored. These calculations are compared to experimental impedance measurements for validation of the model.
Study of Wigner crystal in n-GaAs/AlGaAs by surface acoustic waves
Authors: Suslov Alexey V. , Drichko Irina L. , Smirnov Ivan Y. , Pfeiffer Loren N. , West Ken W. , Galperin Yuri M.
Published: October 2015

The surface acoustic wave (SAW) technique was used for studying a 65 nm wide GaAs quantum well containing a two dimensional electron system (2DES) with the density of 5·1010 cm-2 and the mobility of 8·106 cm2/V·s. A SAW propagated in proximity of the quantum well. Both SAW attenuation α and SAW velocity V were measured in perpendicular magnetic field of up to 18 T in the frequency f range 28.5–306 MHz at temperatures 40–380 mK. Then, both real and imaginary parts of the ac conductance σ(f) = σ1(f) + i·σ2(f) of the 2DES were calculated from α and V. Dependencies of α, V, σ1, and σ2 on magnetic fields showed a rich oscillation pattern, in particular, the fractional quantum Hall effect (FQHE). Thus, at low temperature, the FQHE state was observed at the filling factor ν = 0.20, whereas, in vicinity of this value, at ν = 0.19 and 0.21, the 2DES behaved as a 2D Wigner crystal weakly pinned by a disorder random potential. The calculated pinning frequencies at high and zero magnetic fields were 193 MHz and 12.4 GHz, respectively, and the correlation length of the random potential was 10-2 cm. [Work supported by RFBR 14-02-00232, NSF DMR-1157490, the State of Florida, the Gordon and Betty Moore Foundation GBMF2719, and NSF MRSEC-DMR-0819860.]
The acoustic study of soil liquefaction effects in-situ
Authors: Konkov Andrey , Lebedev Andrey , Manakov Sergey
Published: October 2015

This study is aimed to describe effects of saturation with water on soil stiffness and bonds strength. Linear and nonlinear soil acoustic characteristics as dependent on saturation have been studied in-situ. At the end of experiment, the soil became unstable that allowed tracking the saturation process as a whole. The experiment was prepared as follows. Two weeks before the experiment fulfilment, the trench was dug and a hose with holes was embedded. The hose was connected to the water supply network through the water meter. During saturation, the soil acoustic responses were being continuously recorded. The soil linear stiffness has been measured by remote technique based on the analysis of the dispersion of Rayleigh wave polarization. The measurements were carried out by pairs of vertically and horizontally oriented geophones. Then, the bulk stiffness and the Poisson's ratio profiles were reconstructed. Special attention was given to the assessment of its nonlinear parameters. Effects of hysteresis nonlinearity in dependence “force versus displacement” were observed and discussed as well. The force and displacement were measured by two accelerometers mounted on the baseplate and the reaction mass of vibrational source. [The work was partially supported by RFBR, research projects No.14−02−00695, 15−05−08196, 15−45−02450, and 14−05−31249.]
Parametric study of an ultrasonic non-destructive testing problem based on the reciprocity principle and a hybrid numerical method
Authors: Lyonnet Florian , Cassereau Didier , Cugnet Marie-Françoise
Published: October 2015

Numerical simulations are needed for both the design and the improvement of Ultrasound Non-Destructive Testing techniques in industry. One typical configuration is the pulse echo immersion testing of a material with a possible crack. This is a large and multiscale elastodynamic problem, for which the computation may be intensive using standard discrete methods. Different approaches have been proposed to gain efficiency in terms of the computation time, as i) the hybridization of a discrete method with a semi-analytical formulation or ii) using the reciprocity principle to separate the calculation of the field radiated by the crack from the field in the same material. We present a numerical strategy based on those two approaches in order to perform 3D simulations with a possible parametrization of the crack geometry and location. First, the Spatial Impulse Response (SIR) of a focalized transducer in water is computed using a semi-analytical software. Then, we show that the calculation of the SIR can be pursued in the same elastic material using a FDTD method. To take into account the effects of the crack, this SIR is used in conjunction with the time domain reciprocity equation. This process allows performing an efficient computation of the echo signal from the crack. Results and comparisons with experimental measurements will be presented in a 2D case.
Calculation of vibrational mode contributions to sound absorption in excitable gases by decomposing multi-relaxation absorption curve
Authors: Zhang Ke-Sheng , Zhu Ming , Li Chun , Ou Weihua
Published: October 2015

Molecular vibrational relaxation is responsible for the sound relaxational absorption in most excitable gases. However, it is desirable to calculate the contribution of each vibrational mode to sound multi-relaxation absorption. In this paper, first, a sound multi-relaxation absorption curve is decomposed into the sum of single-relaxation curves; second, based on this decomposed characteristic, a model to quantitatively analyze the vibrational mode contributions to sound absorption is proposed. The simulation results quantitatively demonstrates that the primary relaxation process connected with the lowest mode is the decisive factor for sound relaxational absorption, and the mode with lower vibrational frequency supplies higher contribution to the primary relaxation process in pure polyatomic gases.
Acoustic transmission from a single crystal layer of nonlinear resonators in a soft elastic matrix
Authors: Viard Nicolas , Fang Nicholas
Published: October 2015

Ultrasound transmission measurements of a single crystal layer of identical nonlinear resonators are reported for frequencies under 1 MHz. The resonators are spherical gas-filled cavities embedded in a soft elastic matrix. The cavities are formed by injection of gas through a capillary tube in a polymer solution right before it cures. Sample characteristics such as the size or the spacing between the cavities are adjusted by varying the injection parameters. Typical size for the cavities ranges from 100 μm to 1 mm. The sample is immersed in water where transmission measurements are conducted. As allowed by acoustic transducer, amplitude and phase of the wave is measured in transmission as a function of the frequency and the amplitude of the initial incident pulse.