bluuebunny/crossref_metadata_2025 huggingface dataset:
Understanding bone-conduction hearing: Measurements and model development
Authors: Bowers Peter N. , Ravicz Michael E. , Rosowski John J.
Published: June 2017

Bone conduction (BC), the transmission of sound to the inner ear by way of skull vibration, is thought to stimulate the inner ear by several mechanisms: external ear (vibration of the ear-canal walls), middle ear (ossicular inertia), and inner ear (inertia of the cochlear fluids, compression of the cochlear walls, and sound flow through “third windows”). In chinchilla, we explore the inner-ear mechanisms with measurements of compound action potentials and intra-cochlear sound pressures after manipulations of the middle and inner ear. These measurements suggest that while contribution of cochlear fluid inertia to BC is reduced by occlusion of both cochlear windows, effects of cochlear compression and/or sound pressure transmission via “third window” pathways increase. We also explore external-ear mechanisms by applying an analytically-derived reverse input impedance of the external-ear canal, pre-existing measurements of middle-ear input impedance, and new measurements of ear canal sound pressure. We define an equivalent volume velocity source representative of the combined BC external-ear mechanisms. Estimates of the source magnitude are in agreement with experimental data (Chhan et al., 2016), showing that during ear-canal occlusion, the ear-canal source is a significant contributor to BC hearing at mid-frequencies (1-3 kHz).
Accounting for verbal and spatial working memory load in an auditory Stroop task
Authors: Riffle Travis L. , DiGiovanni Jeffrey J.
Published: June 2017

The Stroop task (Stroop, 1935) has been used extensively in cognitive psychology research for the study of selective attention and processing speed and accuracy. A recent experiment in our lab used an auditory-spatial Stroop task where participants were required to determine the spatial location of congruent and incongruent directional words. Results of that experiment showed that incongruent trials had a significant effect on performance, but only in the vertical plane. Special load theory (Park, Kim, & Chun, 2007) states that distractibility is a function of the relationship between working memory (WM) load and the targets/distractors of the task. The auditory-spatial Stroop task was modified by using WM loads intended to interfere specifically with the semantic or spatial aspects of the task. Given that targets in the task are the spatial locations of the words, special load theory predicts that a spatial WM load results in decreased performance (increased interference) while a verbal WM load predicts increased performance (decreased interference). Data presented will illuminate whether spatial or verbal WM load has a greater impact on performance in an auditory-spatial Stroop task.
Investigating audition with a generative model of impact sounds
Authors: Traer James , McDermott Josh
Published: June 2017

When objects collide they vibrate and emit sound. Physical laws govern these collisions and subsequent vibrations. As a result, sound contains information about objects (density/hardness/size/shape), and the manner in which they collide (bouncing/rolling/scraping). Everyday experience suggests that human listeners have some ability to discern material and kinematics from impact sounds. However, the accuracy of these perceptual inferences remains unclear, and the underlying mechanisms are uncharacterized. Listeners could rely on stored templates for particular familiar objects. Alternatively, we could infer generative parameters for a sound via probabilistic inference in an internal model of the generative process. To explore these possibilities we constructed a generative model of impact sounds, modeling sounds as the convolution of a time-varying impact force with the impulse responses (IRs) of two objects. The force was modeled as a function of mass, hardness and impact velocity. IRs were measured from a range of objects using contact speakers and microphones to measure an object’s effect on vibrational input. IRs for arbitrary objects were generated via interpolation between recorded examples. The model generates compelling renditions of impact sounds. Physically motivated alterations to the force and/or IRs produced physically plausible synthetic impact sounds that can be used in perceptual experiments.
Sonification of a friction sensor for an acoustic characterization of the human skin
Authors: Petiot Jean-François , Bigouret Armelle , GAGNAIRE Sonia , Nkengne Alex , ZAHOUANI Hassan , Vargiolu Roberto , FOUÉRÉ Ludovic
Published: June 2017

The friction properties of surfaces can be investigated via acoustic sensors that measure the noise generated during the sliding of the probe on the surface. This work presents a characterization of the human skin using a friction sensor, designed to measure the signal generated during the interaction between the finger of the experimenter and the skin of a subject. A panel of subjects with different skin characteristics (age, hydration, firmness) was first measured and supervised learning algorithms were used to infer the typology from the labeled data and the signals of the sensor. Next, a sonification of the signals was designed to make audible the differences between the skin categories. The sonification is based on a sound synthesis of a bowed string musical instrument, the violin, which mimics the interaction of the finger on the skin and constitutes a relevant metaphor. From the synthetized sounds corresponding to different experimental conditions (before and after the application of a cosmetic product), hearing tests were performed with a panel of experts. Results show that noticeable differences between the sounds can be highlighted that could make possible to test the efficacy of a product and to promote it with an original musical universe.
Infants' use of onset asynchrony in the segregation of concurrent vowels
Authors: Oster Monika-Maria , Werner Lynne A.
Published: June 2017

Separating speech from competing speech is a difficult task for infants even though their ability to encode sounds appears to be mature. One possible explanation is that infants have greater difficulties extracting speech from the complex sound mixture arriving at their ears. Adults use acoustic cues such as differences in onset or harmonicity to group components that belong to the same sound source and separate those that do not. The sparse evidence on how infants segregate sounds indicates that they use some of these acoustic cues. However, temporal cues, which are strong cues for adults, have not been investigated in infants. This study examined infants’ ability to use onset asynchrony cues to separate simultaneous vowels using a single-interval observer-based procedure. Three- and seven-month-old infants and young adults were trained to identify one target vowel in a modified double-vowel paradigm. Listeners were tested in a simultaneous onset condition and either a 100 or 200 ms asynchrony condition. Cue benefit was defined as the improvement in sensitivity resulting from the addition of the asynchrony cue. Pilot data indicates that an onset asynchrony of 100ms improves performance for all age groups and that the cue benefit increases with age.
Analysis on decorrelation effect of audio signal in multichannel reproduction
Authors: Rao Dan
Published: June 2017

Decorrelation of audio signal is a process that generates two or more incoherent signals from a single input signal, which has many applications in artificial auditory effects, such as broadening the apparent source width (ASW), enhancing the subjective envelopment, producing subjective diffusion in multichannel reproduction, etc. Frequently used decorrelation method is convoluting audio signal with random (or pseudo-random) noise. In this work, we focus on the relationship of reproduction zone of multichannel reproduction with decorrelation degree. Simulation calculation result show that, by changing the decorrelation degree which is measured by the interaural cross-correlation coefficients (IACC) of reproduced signals, the timbre will change when move off the listening center. Listening zone with small timbre deviation (for example, binaural loudness spectra less than 1dB/ERB) relative to center position increase with the value of IACC decrease. But as well known, for good subjective diffusion, the least IACC value does not mean the best effect. There exit a best IACC value range from 0.2~0.4 for different audio signal. Adapting a best IACC value, a reproduction zone across different frequencies can be achieved.
Does hearing loss affect the use of information at different frequencies? Results from a simultaneous tonal pattern discrimination task in normal-hearing and hearing-impaired listeners
Authors: Roverud Elin , Best Virginia , Dubno Judy R. , Mason Christine , Kidd Gerald
Published: June 2017

This study extends previous work [Roverud et al., Trends Hear, 20, 1-17, 2016] reporting differences between normal-hearing (NH) and hearing-impaired (HI) listeners in their use of low- vs. high-frequency information. In that study, listeners identified well-learned tonal patterns presented simultaneously at two center frequencies (CFs). The CFs corresponded to lesser and greater hearing loss in the HI group. Despite matched identification performance at each CF in quiet, when patterns were presented simultaneously, HI listeners were better able to identify patterns at the CF corresponding to better hearing. Here, we extend that work using a discrimination rather than identification task, with less reliance on recall. Each trial consisted of three intervals, each containing simultaneous tonal patterns at two CFs. Individual frequency discrimination thresholds were used to set the separation between elements within each pattern, ensuring equal discriminability across listeners and CFs. The first (referent) interval contains two simultaneous random-frequency patterns, one at each CF. One of the two sequential comparison intervals contains a match to the referent pattern at one of the CFs, and the listener indicates the comparison interval containing the match. Results examining differences for the two CFs across NH and HI listeners will be presented. [Work supported by NIH/NIDCD.]
Effects of induction sequences on the tendency to segregate auditory streams: Exploring the stream biasing effects of constant- and alternating-frequency inducers
Authors: Rajasingam Saima L. , Summers Robert J. , Roberts Brian
Published: June 2017

The extent of stream segregation for a test sequence comprising high- (H) and low-frequency (L) pure tones, presented in a galloping rhythm (e.g., LHL-LHL-…), is much greater when preceded by a constant-frequency induction sequence matching one subset of the constituent tones (e.g., L-L-L-L-…) than by an inducer of the same duration configured like the test sequence. This difference persists for several seconds after the test sequence begins. The origin of this effect was explored using short (2 s) induction sequences followed by long (16-20 s) test sequences. In experiment 1, LHL- sequences were used and one or other subset of the inducer tones was attenuated (0-24 dB in 6-dB steps, and ∞). Greater attenuation of either subset led to a progressive increase in the segregation of the subsequent test sequence, towards that following the constant-frequency inducer. In experiment 2, HLH- sequences were used and the frequency of the L-subset of inducer tones was raised or lowered relative to their test-sequence counterparts. Either change increased subsequent stream segregation. These outcomes support the notion of stream biasing—that constant-frequency inducers promote segregation by capturing the matching subset of test-sequence tones into an on-going, pre-established stream. [Work supported by Aston University.]
Auditory sequential integration of spectral cues revealed using an informational masking paradigm
Authors: Shen Yi
Published: June 2017

When a target tone is embedded in a six-tone, random-frequency masker, a preview of the masker, i.e., a precursor, would provide a priori knowledge with regard to the masker, leading to release from informational masking. In the current study, the precursor was in the form of a sequence of 50-ms, six-tone bursts, and the effect of precursor was evaluated through the detectability of the target. In Experiment 1, each burst in the sequence matched the spectral content of the masker. As the number of bursts increased, the precursor gradually became a more effective cue. On the other hand, the effect of inter-burst interval was not significant. In Experiment 2, each of the six tones in each of the precursor burst was presented with a probability p, therefore the spectral information in each burst was incomplete. As the number of bursts increased, a lower value of p was required to maintain the detectability of the target tone, suggesting that listeners were able to integrate information over time. As the inter-burst interval increased from 0 to 200 ms, the sequential integration became less efficient.
Assessment of the human ability to reproduce known sounds via a synthesis procedure
Authors: Lentz Jennifer
Published: June 2017

One method used to measure the properties of tinnitus perception is allow listeners to “synthesize” their tinnitus by summing sounds of various center frequencies, intensities, and bandwidths. The values of the parameters can be set by the listener, and the acoustic parameters of the resultant sound are thought to describe the characteristics of an individual’s tinnitus. However, the validity of this method is unknown. Here, we present data establishing the abilities of normal-hearing listeners to reproduce the acoustics of known stimuli including pure tones, complex tones, and noises containing various bandwidths and frequencies. Of particular interest is the validity of this method in estimating acoustic properties of high-frequency sounds >8kHz. Results will be interpreted in the context of the limits of auditory perception and in the context of data collected on listeners reporting tinnitus of tonal and noisy qualities.
Effects of temporal coherence and signal-frequency uncertainty for tone detection in a random-frequency multi-tonal masker
Authors: Buss Emily , Dai Huanping
Published: June 2017

Detection thresholds tend to be lower when the spectral and/or temporal characteristics of the signal are predictable than unpredictable, particularly in an unpredictable masker. The present study evaluated the detrimental effect of frequency uncertainty and the beneficial effect of temporal coherence for a pure-tone signal presented in a multi-tonal masker with unpredictable frequency sequences. Stimuli were composed of 80-ms tone bursts. The signal was 1, 2, 4, or 8 sequential tone bursts, and burst frequency was either fixed across trials or randomly varied across trials but fixed across bursts. The masker was composed of four streams of tone bursts; the frequency of each burst was randomly drawn from a uniform distribution 250-4000 Hz, with the caveat that synchronous masker and signal bursts were separated by 1/5 oct or more. Signal and masker bursts were synchronously gated, and the masker played continuously throughout a threshold estimation track. Thresholds tended to improve with increasing numbers of signal bursts and worsen with increasing signal frequency uncertainty. These factors appeared to interact; signal frequency uncertainty was less detrimental when the signal was composed of larger numbers of bursts. Preliminary models of detection will be discussed.
A multi-second adaptive integration process underlies sound texture perception
Authors: McWalter Richard , McDermott Josh
Published: June 2017

Temporally homogenous sound textures—as produced by rain, fire or insect swarms—are thought to be represented with time-average statistics measured from early auditory representations. We explored the averaging process involved in sound texture perception using “texture steps”—stimuli whose statistics changed at some point in time. We reasoned that judgments should be biased by the stimulus history included in the averaging process. Listeners were presented with two sounds, a texture step and a probe texture (with constant statistics). Listeners were asked to compare the endpoint of the texture step to the probe and to select the sound that was most similar to a familiar reference texture. Judgments were biased by the presence of a step 1 second prior to the stimulus endpoint, but the bias was reduced when the step occurred 2.5 seconds from the endpoint. In addition, the bias was substantially larger for textures whose statistics were less homogenous (ocean waves) than textures whose statistics were more homogenous (rain). The results suggest a texture integration process operating over several seconds, but whose integration window is adapted to the homogeneity of the sound signal, averaging over longer periods of time for more variable textures.
Different vibration modes of the Organ of Corti due to mechanical and electrical stimuli
Authors: Zhou Wenxiao , Jabeen Talat , Nam Jong-Hoon
Published: June 2017

The organ of Corti complex (OCC) is highly organized with structurally significant matrices such as the tectorial and basilar membranes and cells such as the pillar cells, Deiters cells and outer hair cells. It is getting clearer that the fine structures in the OCC vibrates out of phase under certain conditions. The functional consequence of the complex vibration modes is unclear. We present our computational and experimental results on different vibration modes of the OCC. Using a custom-fabricated micro-chamber, the vibrations of isolate OCC due to mechanical and an electrical impulse were measured. The same conditions were simulated with a computer model. When there is no outer hair cell feedback, the OCC fine structures vibrate in phase upon a mechanical impulse. With the outer hair cell feedback, initial response is similar to the passive case, but after first couple of oscillatory cycles, the top and bottom surfaces of the OCC vibrate out of phase, similar to the response to an electrical impulse. Our measurements and model simulations show that the outer hair cell’s mechanical feedback modulates the OCC vibration modes.
Assessment of hearing in coma patients employing auditory brainstem response, electroencephalography, and eye-gaze-tracking
Authors: Czyzewski Andrzej , Kostek Bozena
Published: June 2017

The results of the study conducted by Tagliaferri et al. in 12 European countries indicate that the ratio of registered brain injury cases in Europe amounts to 150-300 per 100 000 people, with the European mean value of 235 cases per 100 000 people. The project presented in the paper assumes development of a combined metric of patients’ state remaining in coma by intelligent fusion of GCS (subjective Glasgow Coma Scale or its derivatives) with objective data acquired using ABR (Auditory Brainstem Response), EEG (electroencephalography), and EGT (Eye-Gaze-Tracking). Variety of coma patients from cooperating medical care centers were examined. Senses examination involved the assessment of their function by a medical specialist, with special attention paid to hearing tests results obtained with an ABR measuring device. The assessment included speech-based cognitive functions such as comprehension, phonematic hearing and auditory gnosia. Achieved results are discussed in the paper showing that most patients remaining in coma after a severe brain injury have preserved the ability to receive sound stimuli. [The project was partially funded by the Polish National Science Centre on the basis of the decision No. DEC-2014/15/B/ST7/04724.]
Toward real-time assessment of material properties using elastic guided waves
Authors: Bochud Nicolas , Laurent Jérôme , Bruno François , Baelde Aurélien , Royer Daniel , Prada Claire
Published: June 2017

Elastic guided waves are one of the most promising quantitative ultrasound techniques for the assessment of elastic properties in plate-like structures. Measurements of guided waves, associated with suitable waveguide modeling, can yield accurate estimates of waveguide properties like thickness and stiffnesses. Such a model-based approach requires solving a multi-parametric inverse problem to match experimental data with guided modes. Sensitivity studies suggest that isolated areas of the dispersion curves have predominant influence on specific model parameters. In particular, guided waves in a free plate exhibit a resonant behavior at frequencies where their group velocity vanishes while their phase velocity remains finite (so-called zero-group velocity Lamb modes). In this study, we investigate the feasibility of exploiting targeted data in the vicinity of these particular points, along with data associated with the cut-off frequencies. To this end, guided waves measurements are performed on a series of materials (anisotropic plates and tri-layer structures) using a linear multi-element transducer array and dedicated signal processing. A genetic algorithm-based inverse problem is then solved to recover the waveguide properties. Preliminary results indicate that, owing to the measurements versatility in terms of acquisition speed, this approach has the potential for inferring reliable structural and material properties in real-time.
Acoustic emission to probe slow dynamics in complex materials
Authors: Bentahar Mourad , Yue Xiaoyang , Mechri Charfeddine , Montresor Silvio
Published: June 2017

Acoustic emission has already been applied to give complementary information on the evolution of nonlinear behavior microcracked materials. In particular, energies of elastic waves emitted during the creation and propagation of microcracks in composites revealed to be in good correlation with relaxation time [1]. However, it remains important to study the relaxation (and/or conditioning) of complex materials as a function of mechanisms that lie behind the experimental observations. In this contribution, composite and concrete samples taken at microcracked states are submitted to slow dynamics experiments. Acoustic emission hits recorded during conditioning are first presented. During the high level excitation, the pump signal is at a very low frequency (few hundreds of hertz) in order to separate clearly the acoustic emission activity (> 50 kHz) and the low frequency excitation. Relaxation of complex materials has been realized with and without a probing ultrasonic wave. Results revealed that despite the weak acoustic emission activity, recorded acoustic emission hits contain enough information in order to improve our understanding of relaxation probed in complex materials. [1] M. Bentahar, R. El Guerjouma, “Monitoring progressive damage in polymer-based composite using nonlinear dynamics and acoustic émission.” Acoust. Soc. Am. 125, EL39 (2009).
Study of the mechanical properties of thin films involved in ophthalmic glasses
Authors: FAESE Frederic , Poinot Delphine , Djemia Philippe , Chatel Sebastien , Belliard Laurent
Published: June 2017

The mechanical properties of thin films involved in the manufacturing of ophthalmic glasses have been investigated by two complementary laser based techniques. On the one hand, picosecond ultrasonics (PU) measurements allows to determine the acoustical longitudinal velocity in the sample, hence the elastic constant c11. On the other hand, Brillouin light scattering (BLS) measurements leads to the value of the transverse velocity, hence c44. In the case of isotropic materials, these two coefficients give a direct access to the value of the Young’s modulus and Poisson’s ratio of the film. The influence of the film characteristics on its mechanical properties will be discussed, mainly regarding its thickness and the manufacturing process. Another issue concerning the effect of the film environment will be addressed. Especially, we will discuss the influence of the substrate on the mechanical properties of a single film, and the link between the mechanical properties of a single film and the ones of a films stacking.
Ultrasonic measurements by means of continuous waves in a foam saturated with air
Authors: Longo Roberto , Duclos Aroune , Groby Jean-Philippe
Published: June 2017

The study of porous materials has always been of great interest. Several characterization methods have been developed by means of ultrasonic waves, mainly because of their non-invasive behavior. A typical set-up involves transmission and reflection measurements through the test material using pulse signals. The received echoes are analyzed and compared with analytical models in order to estimate some specific acoustic properties of the sample itself. The main drawback of this approach is the low signal-to-noise ratio recorded when testing highly attenuating materials. This disadvantage is even more pronounced for measurements in air. The present work aims to overcome these limitations, replacing the excitation signals by continuous muti-harmonic waves. These signals have been developed by optimizing the phase of each harmonic, resulting in a low crest factor and consequently in a better signal-to-noise ratio Moreover their frequency content can be easily adapted to the different transducers used during the test. The method has been used to test a foam saturated with air, performing ultrasonic measurements in transmission/reflection, at different angles of incidence. The results show a significant improvement of the measurements, facilitating the estimation of the foam acoustics properties.
Non destructive evaluation of adhesion quality in a bi-material structures
Authors: Chehami Lynda , Declercq Nico
Published: June 2017

The difficulty of applying ultrasonic techniques to bi-material structures lies in the fact that different phenomena coexist, such as the non-linear effects caused by the adhesion properties between matrix-fibers and the diffraction effect caused by the periodicity of those structures. This work deals with the study of the combined effect of non-linear effects on a 3D bi-materials structure “polymer-titanium.” For this purpose, a Snapscan system is used which generates high amplitude pulses and receives signals composed of the fundamental mode and the higher harmonics. The transducers used are chosen according to the thickness and the periodicity scale of the sample. First, measurements in transmission are made where the transmitted ultrasonic waves are measured by changing the angle between the receiver and the sample. For each angle, a spectrogram is realized. The experimental observations on the spectrograms show that for small incident amplitudes we measure only the fundamental frequency. When the amplitude is gradually increased, high harmonics are generated due to the non-linear stress-strain relationship. Then, reflection measurements were made to measure the Bragg spectrum. The results show that the internal defects (due to lack of adhesion) disturb the periodicity of the structure and thus the Bragg spectrum. This non-destructive technique can be a valuable aid for the automotive industry, for example, in order to control their products during manufacturing process.
Optimization of time reversal focusing in resonant and non-resonant systems through various signal processing techniques
Authors: Young Sarah M. , Willardson Matthew L. , Denison Michael , Furlong Trent , Anderson Brian E.
Published: June 2017

This research optimizes a time reversal focus of energy in terms of amplitude and quality by exploring several signal processing techniques applied to the reversed impulse response. Techniques explored here include deconvolution or inverse filtering [M. Tanter et al., J. Acoust. Soc. Am. 108, 223-234 (2000)], one-bit time reversal [A. Derode et al., J. Appl. Phys. 85, 6343-6352 (1999)], and a new technique termed “clipping.” A parameterization study comparing the maximum focal amplitude and focal temporal quality of time reversal focal signals for these techniques with different settings will be presented. Focal signals are explored in two different systems. The first is a resonant system comprised of a steel sample with a piezoelectric transducer and a scanning laser Doppler vibrometer (SLDV). The second, nominally non-resonant system, comprises a studio monitor loudspeaker and a precision microphone in a reverberant space above the Schroeder frequency. Comparing the focal quality of various time reversal techniques in two starkly different systems shows the optimal conditions for focusing in each system.
Acoustic waves in fluid-solid nested cylindrically layered structures: Theoretical investigation
Authors: Liu Yang , Sinha Bikash K. , Zeroug Smaine
Published: June 2017

Understanding the complex elastic-wave physics prevalent in fluid-elastic cylindrically-layered structures is of importance in many NDE fields, and most pertinently in the domain of well integrity evaluation in the oil and gas industry. Well construction requires lowering steel casings into the hole and cementing them to the wellbore as well as to each other so as to provide mechanical support and enable control over the channeling of the produced fluids—thus preventing unwanted leakage of hydrocarbons to the surface or shallow aquifers. Evaluating whether cement has cured and sealed the desired annuli between casing strings and between the outer string and rock formation is important to ascertain before putting the well in production. In this talk, we establish a mathematical framework to analyze the guided wave fields in a dual-string system embedded in infinite media—a configuration that is of great significance in oil field. We introduce a novel Sweeping Frequency Finite Element Modeling (SFFEM) method to investigate the dispersions and modal characteristics of the complex propagating signals synthesized over an axial array of receivers. The SFFEM provides for a flexible framework to study the modal sensitivities in a multi-string system with arbitrary eccentricity, azimuthal heterogeneities, and partial bonded interfaces.
Acoustic waves in fluid-solid nested cylindrically layered structures: Experimental validation
Authors: Liu Yang , D’Angelo Ralph M. , McGowan Larry , Sinha Bikash K. , Zeroug Smaine
Published: June 2017

This abstract describes an experimental study that accompanies the theoretical development reported in a companion abstract “Acoustic waves in fluid-solid nested cylindrically layered structures: theoretical investigation.” Scaled laboratory experiments are conducted to acquire reference data used to verify the modeling approach developed to predict the guided modal characteristics of axially-propagating waves in concentric and non-concentric cylindrical structures immersed in fluid. These structures simulate the geometries and environment encountered downhole when conducting acoustical measurements to evaluate the cementation of oil and gas cased wells. Typically, cement is expected to fill the annular space between the two nested steel casing strings and between the outer string and rock formation. Measurements are made in concentric, and non-concentric, dual-string steel pipe of ¼ scale that are suspended in an immersion tank. The acquired data set is then analyzed for modal content using both Slowness-Time-Coherence and modified Matrix Pencil methods and compared to theoretical predictions. A comparison of the experimental and numerical results indicates that the Sweeping Frequency Finite Element (SFFEM) is capable of accurately reproducing the higher order multiple wave fields observed experimentally in the fluid-filled double string geometries.
Random matrix theory and complexity in structural acoustics and vibrations
Authors: Weaver Richard
Published: June 2017

I present a short synopsis of (the Gaussian Orthogonal Ensemble, or GOE, of) Random Matrix Theory, and its relevance for Structural Acoustics. It is argued that, if a structure is generic, lacking special symmetries and with dynamics that depends on uncontrolled or unknown details, i.e, is complicated, then its stiffness matrix is—for many purposes—as if it were taken from the Gaussian Orthogonal Ensemble of matrices. Such matrices are symmetric and real with uncorrelated Gaussian entries, and have no preferred directions, that is—it is an ensemble whose statistics are invariant under orthogonal transformations. The consequences are several predictions for the statistics of high frequency responses, including those due to level repulsion, spectral rigidity, and Gaussian random modal amplitudes, predictions that appear to be well satisfied in practice. We discuss why and when the GOE should be relevant to real structures whose stiffness matrices are clearly not, to most appearances, typical members of this ensemble.
Modal analysis of vehicle engine-transmission unit: Finite element model and experimental investigation
Authors: Langer Patrick , Guist Christian , Sepahvand Kheirollah , Marburg Steffen
Published: June 2017

The scope of this work is to enhance the reliability of three dimensional finite element (FE) models for modal analysis of engine-transmission of vehicles taking into account uncertainties. Uncertainty sources may be due to the system characteristics such as geometry, material behavior, boundary conditions and mesh density or as results of assumptions made during the modeling. To this end, the natural frequencies of the entire unit are computed numerically using a 3D FE model and compared to experimental results obtained from the non-contact experimental modal analysis using Laser Doppler Vibrometer (LDV). Essential experiences and knowledge are collected from primary experimental investigations on single and bolted joints beam-like components. This helps to identify uncertainty sources and limitations in FE modeling. Finally, uncertainties due to the initial torque of bolted connections and boundary conditions associated to the unit are considered. The FE model then is updated to achieve accurate results compared to experimental data. In addition to accomplish a reasonable accurate model for the investigated system, the gained experiences and results in this paper can be employed as general guidance and references for FE modeling of real complex engineering systems.
Modal response uncertainty in structural acoustic systems using generalized polynomial chaos expansion
Authors: Wixom Andrew S. , Martinelli Sheri , Shepherd Micah R. , Hambric Stephen , Campbell Robert
Published: June 2017

When knowledge of material design parameters is lacking, it is important to understand how this uncertainty effects the system response. Generalized polynomial chaos (gPC) expansions provide a means for quantifying this uncertainty and typically show good agreement with Monte Carlo techniques at a much reduced cost [K. Sepahvand et al. / Applied Acoustics 87 (2015) 23-29]. In this work, we apply gPC expansions to study the effects of design parameter uncertainty on a structure’s modal characteristics—both eigenvalues and eigenfunctions. The gPC expansions permit the propagation of uncertainty from the design parameters to the modes and natural frequencies, which then characterize the vibration response of the system as a function of the random parameters. The response uncertainty can then be described using the solutions of the deterministic system sampled carefully over the parameter space. Uncertainty in the forcing function can also be included in this formulation. Numerical calculations demonstrate these techniques to predict the structural acoustic uncertainty of a vibrating plate with the results validated against Monte Carlo simulations. The effects of uncertain forcing functions will also be discussed.
Using smartphone apps to map phonetic variation in British English, German, and Swiss German
Authors: Leemann Adrian
Published: June 2017

Traditional data collection methods in dialectology have difficulty in gathering sufficient quantities of data from a sufficient range of localities to map phonetic variation at a national scale. By contrast, online surveys, whether browser-based or in the form of smartphone apps, allow researchers to gather much larger quantities of data very quickly. We present results from data collected through such smartphone apps for 100K + speakers of British English, German, and Swiss German. Our apps ask users a set of questions about their language use—such as do they pronounce the 'u' in ‘butter’ as /ʌ/ or /ʊ/ (eliciting the FOOT-STRUT split)—and uses their responses to predict their locality of origin. When selecting their regional variant, users essentially perform a perception task, as they listen to pre-recorded items to make their decision. Using this data we can perform analyses of language change, comparing contemporary data with historical surveys, such as the Survey of English Dialects form the 1950s. The second functionality allows users to provide production data—recording ten sentences per speaker. Both, the prediction and recording functionality enable large-scale, unprecedented analyses of national and regional phonetic variation. In this contribution, we further discuss the challenges and potential of this paradigm of data collection.
Crowd-sourcing prosodic annotation
Authors: Cole Jennifer , Mahrt Timothy , Roy Joseph
Published: June 2017

Much of what is known about prosody is based on native-speaker intuitions of idealized speech, or on prosodic annotations from expert annotators trained to interpret a visual display of f0. These approaches have been deployed to study prosody primarily in languages accessible to university researchers, and largely based on small, homogenous speech samples from college-aged adult speakers. We describe an alternative approach, with coarse-grained annotations collected from a cohort of untrained annotators performing real-time Rapid Prosody Transcription (RPT) using LMEDS, an open-source software tool we developed to enable large-scale, crowd-sourced prosodic annotation over the internet. We compared nearly 100 lab-based and crowd-sourced RPT annotations for a 300-word, multi-talker sample of conversational American English, with annotators from the same (US) vs. different (Indian) dialect groups. Results show greater inter-annotator agreement for same-dialect annotators, and the best overall reliability from crowd-sourced US annotators. Statistical models show that a common set of acoustic and contextual factors predict prominence and boundary labels for all annotator groups. Overall, crowd-sourced prosodic annotation is shown to be efficient, and to rely on established cues to prosody, supporting its use for prosody research across languages, dialects, speaker populations, and speech genres.
Wildcat Voices: Remote recording using open web standards
Authors: McGowan Kevin B. , Cramer Jennifer
Published: June 2017

The University of Kentucky is conducting a speech production study with the goal of recording every member of our roughly 29,000 graduate, undergraduate, and professional students--the `Wildcat Voices' project: http://voices.uky.edu/. This talk describes the technology supporting this project, the strengths and shortcomings of this technology, and the challenges of crowd-sourcing a large database of recordings. The web site is written using open web standards including HTML5 Audio and Javascript. Participants can record using software already on their computer, tablet, or cell phone. This arrangement minimizes support costs and ensures interoperability with sites like Amazon's Mechanical Turk that do not allow software downloads. The site presents a prompt, records using the device's microphone, stores recordings in a database, and runs forced alignment to create a TextGrid object. Finally, this talk will present production data from the Wildcat Voices project and discuss the challenges of reaching all of the target participants, managing the server and backup infrastructure, and issues with recording quality that one does not face in a laboratory (computer fans, background noise, echo, etc.). Remote collection of speech production data is not without its problems, but the benefits of scalability offered by crowd-sourcing production studies are tremendous.
Crowdsourcing speech intelligibility judgments
Authors: Wolters Maria K. , Isaac Karl B.
Published: June 2017

When we crowdsource judgements about the intelligibility of speech stimuli, the results are similar to those obtained under laboratory conditions, but contain substantially more noise. In this talk, we report on the extent to which self-reported variables such as background noise, headphone type, and hearing ability explain some of this variation in listener judgements. Our data comes from a total of 7 data sets, 4 studies conducted for a PhD thesis (Isaac, 2015; n = 276) and 3 data sets collected from Mechanical Turk for the Blizzard Challenges in 2009, 2010, and 2011 (King and Karaiskos 2009, 2010, 2011; n = 247). The statistical analysis, using generalised linear mixed models, focuses on two outcome variables, word error rate (WER) and perceived difficulty in understanding the sentences. We will discuss the implications of our findings for the design and analysis of large-scale crowdsourced speech intelligibility studies. This discussion will be framed with reference to current best practice in crowdsourcing perception studies.
Comparing the effect of aperture extension on the peak sidelobe level of sparse arrays
Authors: Rawnaque Ferdousi Sabera , Buck John R.
Published: June 2017

This paper compares the performance of Uniform Linear Arrays (ULA), Minimum Redundancy Arrays (MRA) and Co-prime Sensor Arrays (CSA) in terms of the Peak Sidelobe Level (PSL) of their beampatterns. A ULA distributes its sensor elements equidistantly on a line, achieving a PSL of -13.5dB [Van Trees, 2002]. Sparse arrays span the equivalent aperture as a fully populated ULA with fewer sensors providing cost and computational advantages but with higher PSLs. To span a given aperture, MRAs [Moffet, 1968] require the fewest sensors to include all the spatial correlation lags in its co-array [Johnson and Dudgeon, 1993]. A CSA interleaves a pair of ULAs undersampled by co-prime factors [Vaidyanathan and Pal, 2011]. A CSA can be conventionally processed as a single non-uniform array or by product processing of its subarrays. This paper shows only the product processed CSA sharply decreases its PSL with increasing aperture, eventually matching ULA PSLs [Adhikari et al, 2014]. The MRA and linearly processed CSA PSLs remain unaffected by aperture extension, nearly equal to each other and much higher than the ULA PSLs. Thus, the product processed CSA has the best PSL performance among the considered extended sparse arrays. [Work supported by ONR grant N00014-13-1-0230.]
Localization and tracking performance of a stationary compact array of synchronized hydrophones
Authors: Urazghildiiev Ildar R. , Hannay David E. , Moloney John
Published: June 2017

Stationary compact arrays of synchronized hydrophones are an efficient tool to evaluate the azimuth and elevation angles and positions of marine mammals, vessels, and other sources that produce detectable sounds. A compact array designed by JASCO Applied Sciences (Canada) Ltd., was used to estimate the azimuth and elevation angles of ship noise and marine mammal calls and to estimate positions and to track sources from bearing only measurements provided by both single and multiple arrays. Array performance was tested with various sources that transmitted impulsive and continuous sounds; GPS coordinates were known for all sources. Bearing and position accuracy as functions of sound bandwidth, duration, and other parameters, were estimated. Test results demonstrated that the array’s accuracy came close to the Cramér-Rao bounds. In in situ tests, correlated bearing errors were observed. Refraction, surface and bottom reflections and other unpredictable sound propagation effects caused most of the bearing errors. The source position and heading angle estimation accuracy was evaluated using the array deployed in the Strait of Georgia, BC, Canada. Test results demonstrated that the array can provide the highest possible accuracy and can be used in various applications involving long-term passive acoustic monitoring of large areas.
Simulations of source localization in the deep ocean using frequency-difference matched field processing
Authors: Geroski David J. , Dowling David R.
Published: June 2017

Matched field processing (MFP) is an established technique for source localization in multi-path acoustic environments that relies on correlating array-recorded and simulated sound fields. However, when the recorded sound field’s frequency is high enough, this field may be sensitive to details of the acoustic environment that are uncertain or unknown, and therefore not included in the simulated sound field. Thus, the actual and modeled acoustic fields are mismatched, the severity of this mismatch increases with frequency, and may cause MFP to fail at relevant frequencies and ranges in the deep ocean. One remedy to this problem may be analyzing the frequency-difference autoproduct of the acoustic field instead of analyzing the field itself. Thus, this presentation covers the simulated performance, and likely limitations, of frequency difference MFP [Worthmann and Dowling (2015). J. Acoust. Soc. Am. 138, 3549-3562] in a generic deep-ocean channel using a ray code (Bellhop) for the source-broadcast field in the signal bandwidth and a mode code (Kraken) for the replica calculations in the difference-frequency bandwidth. Here, refractive index fluctuations in the ocean are modeled by random time delays for each ray-path between the source and each receiver. [Sponsored by ONR.]
Automatic recognition of accessible pedestrian signals
Authors: Camacho Arturo , Ruiz Blais Sebastián , Fonseca Solís Juan M.
Published: June 2017

Accessible pedestrian signals (APS) enhance accessibility in streets around the world. Recent attempts to extend the use of APS to people with visual and audible impairments have emerged from the area of audio signal processing. Even though few authors have studied the recognition of APS by sound, comprehensive literature in Biology have been published for recognizing other simple sounds like bird and frog calls. Since these calls exhibit the same periodic and modulated nature as APS, many of the existent approaches can be adapted for this purpose. We present an algorithm that uses the mentioned approach. The algorithm was evaluated using a collection of 79 recordings gathered from streets in San José, Costa Rica, where the solution will be implemented. Three types of sounds are available: a low-pitch chirp, a high-pitch chirp and, a cuckoo-like. The results showed a precision of 87%, a specificity of 83%, a sensibility of 86%, and a F-measure of 85%.
A study of characteristics of underwater acoustic particle velocity channels measured by acoustic vector sensors
Authors: Zhang Erjian , Abdi Ali
Published: June 2017

Acoustic vector sensors measure orthogonal components of acoustic particle velocity. When used in underwater communication systems, they act as multichannel receivers. One advantage of a vector receiver, compared to an array of spatially-separated scalar receivers such as hydrophones, is its compact size. Some characteristics of particle velocity channels are studied theoretically or via simulations (A. Abdi and H. Guo, “Signal correlation modeling in acoustic vector sensor arrays,” IEEE Transactions on Signal Processing, vol. 57, pp. 892-903, 2009; H. Guo, et al., “Delay and Doppler spreads in underwater acoustic particle velocity channels,” J. Acoust. Soc. Am., vol. 129, pp. 2015-2025, 2011). In this paper, we use data measured by a vector sensor to study various key characteristics of underwater particle velocity channels, including delay spreads, signal-to-noise ratios, and possible correlations among different channels. By inspecting the eigen structure of channel matrices, we also investigate how various measured particle velocity channel impulse responses can affect the performance of an equalizer to detect transmitted symbols. The results are useful for designing proper vector sensor-based multichannel receivers in underwater communication systems. [This work was supported in part by the National Science Foundation (NSF), Grant IIP-1500123.]