bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling articulation techniques in single-reed woodwind instruments
Authors: Chatziioannou Vasileios , Hofmann Alex
Published: May 2013

Time-domain simulations of wind instruments can, in principle, deal with non-linear oscillations and are also capable of modeling both the steady-state and the transient behavior of a system. The starting transient is usually an important identifying feature of the instrument that is played. Subtle control of articulation is required from skilled musicians to modulate transients during expressive performance. Focusing on single-reed woodwind instruments, the physical phenomena that underlie different articulation techniques are analyzed. A saxophone player is recorded during portato playing, where articulation is achieved either by the use of the tongue, or by modulating the air flow into the mouthpiece. The bending of the reed and the pressure inside the mouthpiece are measured and a physical model is formulated with the aim to capture the transient effects. Instead of adding new terms (and complexity) to a single mass-spring model, in order to simulate the player's tongue, existing physically meaningful parameters are allowed to vary. In particular, the effect of tonguing is modeled by modulating the equilibrium position of the (lumped) reed and its internal damping, whereas in the case of air-separated tones, only a variation of the blowing pressure is required.
Laboratory study on effects of environment noise on children’s short-term memory
Authors: Ma Hui , Gong Shengnan
Published: May 2013

In laboratory settings 18 children of 6-7 years old were asked to finish series of short-term memory tasks under the different sound situation. The noise stimuli used in the experiment were both road traffic noise and low frequency noise of LAeq.2min = 40, 45, and 50 dB to simulate the indoor sound condition when the children at school or at home. The result showed both road traffic noise and low frequency noise had influence on children’s task achievement and significant adverse effects on subjective noise annoyance evaluation. Comparing with the linear dose-response relationship of road traffic noise, the effects brought by low frequency noise to children’s short-term memory work and noise annoyance evaluation was more complicated. There was an interesting trend that higher noise annoyance was evaluated, the higher task marks was obtained. As for the gender difference, boys showed more sensitivity to low frequency noise than girls.
The influence of a focused acoustic field on mass-transfer processes at a heterogeneous boundary
Authors: Kasyanov Dmitry
Published: May 2013

An experiment is conducted on estimating the velocity of a Schlichting boundary flow arising when a focused field falls on a rigid boundary in a liquid. Also temperature increase into the acoustic boundary layer is experimentally estimated in this situation using optic means. The velocity of a small-scale Schlichting flow is determined by an indirect method from the characteristics of the cocurrent Rayleigh flow using the particle image velocimetry method. The velocity of the Schlichting flow attained in experiments gives the possibility of significantly accelerating mass-transfer processes at a heterogeneous boundary, which is confirmed by experimental results on acoustic intensification of rapid growth of salt monocrystals conducted under strictly controlled laboratory conditions. It is shown the increase in the temperature of the boundary layer is insufficient for significant retardation of the crystal growth.
Fast waves, slow waves and cochlear excitation
Authors: Olson Elizabeth S.
Published: May 2013

In idealized cochlear models [especially, Peterson and Bogert, J. Acoust. Soc. Am. (1950)], intracochlear pressure is decomposed into two modes, the compression pressure (fast mode) and the traveling wave pressure (slow mode). Because the cochlear fluid is nearly incompressible, only the slow mode leads to significant motion. In the real cochlea, additional fast modes exist. These evanescent modes are similar to the traveling wave mode in driving significant fluid and tissue displacement. They are present in the region of the cochlear windows, where the anatomy is not the ideal symmetric structure of basic cochlear models. Evanescent modes also have emerged in experimental work in which cochleostomies are made in the apex. At high stimulus level fast modes are able excite hair cells, leading to auditory nerve responses. However, fast mode motions do not seem to be amplified by the cochlear amplifier. This observation supports the concept that the amplifier relies on traveling wave curvature, as has been proposed in cochlear models [for example, Yoon et al., Biophys. J. (2011)]. I will review experimental and theoretical results on the fast and slow waves, and propose experiments in which wavelength-based theories of amplification could be tested.
The elusive hair cell gating spring, a potential role for the lipid membrane
Authors: Kim Jichul , Pinsky Peter M. , Steele Charles R. , Puria Sunil , Ricci Anthony J.
Published: May 2013

Deflection of auditory hair cell hair bundle results in a nonlinear (i.e., non Hookean) force-displacement relationships whose molecular mechanism remains elusive. A gating spring model posits that mechanosensitive channels are in series with a spring such that channel opening puts the activation gate in series with the spring, thus reducing spring extension until further stimulation is provided. Here we present a theoretical analysis of whether the lipid membrane might be the source of nonlinearity. A hair bundle kinematic model is coupled with a lipid membrane model that includes a diffusible compartment into which the tip-link embeds and a minimally diffusive reservoir pool. Using physiological parameters, this model was capable of reproducing nonlinear force-displacement plots, including a negative stiffness component but required a standing tip-link tension. In addition, this model suggests the mechanotransducer channel is most sensitive to curvature forces that are located within 2 nm of the tip-link. [Work supported in part by Grant Nos. R01-DC07910 and R01-DC03896 from the NIDCD of NIH and by The Timoshenko fund from Mechanical Engineering Department at Stanford University].
Spatial consistency as a cue for segregation and localization
Authors: Simpson Brian , Gilkey Robert , Thompson Eric , Brungart Douglas , Iyer Nandini , Romigh Griffin
Published: May 2013

Many real-world auditory scenes are dynamic and complex, with multiple sounds that may change location over time. In this experiment, we examined the ability of listeners to localize a spatially consistent target sound in a dynamic, spatially varying auditory scene. The target and masker stimuli were composed of sequences of 60-ms bursts of uncorrelated noise (2 to 16 bursts in duration) and differed only in their degree of spatial consistency. Specifically, each target burst within a sequence came from the same spatial location (which varied from trial to trial), whereas each masker burst within a sequence came from a different, randomly chosen spatial location. The listener’s task was to localize the spatially-consistent sequence. Localization errors decreased by approximately 11° with each doubling of the sequence duration, and approached quiet performance with 16-burst sequences. Adding a second masker increased localization errors by approximately 14° overall. These results suggest that spatial information can be combined across multiple observations over time to identify and localize a spatially consistent target in a dynamic auditory scene. These data will be discussed in terms of the information obtained from each burst and the manner in which the information is combined across bursts.
Integration of auditory input with vestibular and neck proprioceptive information in the interpretation of dynamic sound localization cues
Authors: Kim Janet , Barnett-Cowan Michael , Macpherson Ewan
Published: May 2013

To determine the front/back location of a sound source via head rotation, the auditory system must integrate sensorimotor information about head motion with the dynamic acoustic cues resulting from motion of the source relative to the head. In order to determine the influence of vestibular and proprioceptive cues on processing of dynamic acoustic cues, we measured, in active, passive, and counter-rotation conditions, listeners' ability to discriminate front/rear locations of low-frequency sounds not accurately localizable without head motion. Targets were presented over headphones during head rotations using dynamic virtual auditory space methods. In the active condition, the subject performed a head-on-body rotation, which provided vestibular and neck proprioceptive information. In the passive condition, proprioceptive information was minimized by whole-body rotation with no neck movement using a motorized rotating chair. In the counter-rotation condition, the subject performed a head-on-body rotation while the body was counter-rotated, which minimized vestibular input by keeping the head still in space. Dynamic acoustic cues corresponded to the head-on-body angle. Discrimination was accurate in active and passive conditions, but near chance under counter-rotation, suggesting that vestibular inputs are necessary and sufficient to inform the auditory system about head movement, whereas proprioceptive cues are neither necessary nor sufficient.
Sound-localization performance with the hearing protectors
Authors: Zimpfer Veronique , Sarafian David
Published: May 2013

Hearing-protection system that provide level-dependent sound attenuation can protect the ear against potentially damaging sounds (such as loud impulsive noises), while at the same time allowing the perception of moderate-level signals (such as speech). Such systems come in two forms: passive (nonlinear-attenuation earplugs) and active (talk-through system). This study sought to quantify the effect of these systems on spatial hearing. To this aim, sound-localization performance was measured in twenty subjects, with and without ear protectors on. Five protectors (two passives and three actives) were tested. The results showed significant increases in the proportions of errors during the use of one of the systems tested. To clarify the origin of this effect, “protected head-related transfer functions” (PHRTFs), i.e., HRTFs obtained with the ear-protectors on, were measured in the horizontal plane for each of the systems tested. The comparisons of these measures between PHRTFs with HRTFs were found to be in agreement with the subjective tests.
On the ecological interpretation of limits of interaural time differences sensitivity
Authors: Hartmann William M. , Rakerd Brad , Macaulay Eric J.
Published: May 2013

Human listeners, and other animals too, use interaural time differences (ITD) to localize pure tones, but this ability abruptly diminishes as the frequency of a pure tone increases. The diminished sensitivity appears to serve a useful function. It prevents the confusion that would otherwise arise from the large interaural phase differences that occur at high frequency as sound waves diffract around the head. Possibly this benefit offers an ecological explanation for the diminished sensitivity of the nervous system. However, comparison of the frequency dependence of ITD sensitivity, as measured in headphone experiments, and the frequency dependence of the physical phase shifts, as measured in an anechoic room, reveals a bad match between these two functions. The decrease in neural sensitivity to ITD is seen to be far too rapid, casting doubt on this form of ecological reasoning. If one wants to maintain an ecological context, it is more plausible to argue that our binaural architecture, with its neurophysiological limitations, evolved when our head diameters were smaller by as much as 50%. [Work supported by the AFOSR, 11NL002.]
Auditory streaming in cocktail parties and the extent of binaural benefit
Authors: Schoenmaker Esther , van de Par Steven
Published: May 2013

Studies that investigate the advantage of spatial separation of speakers in a cocktail party generally focus on one of two processing strategies. The first assumes a top-down mechanism in which the listener focuses attention on the known location of a target speaker. Glimpses of target speech are collected and combined to form an auditory stream. The second strategy makes use of interaural differences in perceptual input and exploits these in order to suppress interfering sounds. Equalization-Cancelation (EC) models typically follow this approach. In order to investigate the contributions of both mechanisms, a headphone experiment was conducted that explores auditory streaming based on binaural cues. Sequences of logatomes spoken by one target and two interfering speakers were presented. In this experiment a new type of stimuli was introduced in which the possibility to use binaural masking release cues was eliminated for each time-frequency interval (glimpse) while the localization cues of the dominating source were preserved. Thus, listeners could attend to spatially separated glimpses, but no EC processing was possible. The effect of the availability of masking release cues on successful streaming will be analyzed and discussed.
The role of spatial detail in sound-source localization: Impact on head-related transfer function modeling and personalization
Authors: Romigh Griffin D. , Brungart Douglas S. , Stern Richard M. , Simpson Brian D.
Published: May 2013

Current techniques designed to personalize generic head-related transfer functions (HRTFs) have some capacity to quickly customize spatial auditory displays, but these techniques generally fall short of the level of realism and performance provided by fully individualized HRTF measurements. This residual performance deficit reflects inaccuracies due to vast amounts of spatial and spectral variation that occurs across the measured HRTFs of individual listeners. Some of this variation encodes perceptually-important directional information, but a substantial proportion does not. Kulkarni and Colburn (1998) showed that perceptually irrelevant spectral variation could be eliminated by smoothing the HRTF magnitude with a truncated Fourier-series expansion. The present study investigates a related method for smoothing the spatial variation contained in the HRTF by utilizing a truncated spherical harmonic expansion. The impact of spatial smoothing was evaluated by comparing localization performance with individualized HRTFs which were fully represented or had various degrees of spatial smoothing. Results indicate that a highly-smoothed fourth-order spherical harmonic representation can produce localization accuracy comparable to that of a full individualized HRTF. Analysis of the resulting simplified HRTF representations also uncovered a number of interesting relationships across different individuals which may provide new insights for the development of future HRTF personalization and estimation techniques.
Analysis of the acoustic scattering from a submerged bilaminar plate
Authors: Hayek Sabih I. , Boisvert Jeffrey E.
Published: May 2013

The acoustic scattering from a submerged finite bilaminar rectangular elastic plate is modeled using the exact theory of three-dimensional elasticity. The two layers of the composite bilaminar plate have the same lateral dimensions, but have different thicknesses and material properties. The plate is set in an infinite rigid baffle and is coupled to a different acoustic medium on its two surfaces. The plate is insonified by an acoustic plane wave. The farfield backscattered and forward scattered waves are computed for various layer thicknesses and elastic material properties in contact with air or water. First, the scattering from a uniform finite, baffled, steel plate elastic plate was computed. A bilaminar plate was also analyzed with one layer made of steel and the other made of a damped elastomer. The backscattered and forward scattered acoustic farfield spectra versus frequency were computed at the on-axis point receiver due to a normally incident plane wave. The directivity functions for a normally incident plane wave insonifying the steel- or elastomer-side of the plate were computed for a range of frequencies, with either water or air backing. [Work supported by NAVSEA Division Newport under the ASEE Summer Faculty Program.]
Experience-dependent learning effects in speech production with spectrally degraded feedback
Authors: Casserly Elizabeth D. , Pisoni David B.
Published: May 2013

This study examined the speech of normal-hearing adult participants before and during their use of a portable, real-time vocoder (PRTV). The PRTV continuously transforms environmental acoustics, including speakers’ own speech feedback, via a real-time simulation of cochlear implant processing. The impacts of this substantial spectral degradation on speech production were measured in three groups of subjects: group 1 received altered acoustic feedback for one continuous 55 min session; group 2 experienced the feedback transformation for one session of 6 h total; and group 3 wore the PRTV for four consecutive sessions of 4 h each, for a total of 16 h of experience. Speakers in each group were recorded producing 114 isolated English words and 24 sentences both before their feedback manipulation began and at periodic intervals during their experimental session(s). Acoustic-phonetic analyses of the speech produced by subjects in all three groups revealed substantial effects of the spectral feedback degradation in several domains, including fluency/speaking rate, vocal affect, and vowel quality. Speakers were able to adjust and recover quickly in some of these areas, such as affect, while other changes, such as those in vowel quality and speaking rate, remained despite 16 h of experience with the acoustic transformation.
The relationship between vocal pitch feedback error and event-related brain potentials
Authors: Jones Jeffery A. , Scheerer Nichole , Tumber Anupreet
Published: May 2013

Understanding the neural processing of auditory feedback during speech is essential to the development of a comprehensive model of speech motor control. Currently, the relationship between the magnitude of errors detected in feedback and the evoked neural responses is unclear. We exposed speakers to sudden changes in vocal pitch that ranged from 0 to 400 cents in magnitude. Vocal responses and auditory event-related potentials (ERPs: P1-N1-P2-N2 components) were measured. Results showed that vocal response magnitudes were relatively consistent when speakers were exposed to small feedback perturbations (<250 cents). Larger perturbations (>300 cents) caused decreased vocal response magnitudes. P1 amplitudes showed a non-specific increase when feedback was perturbed. N1 amplitudes demonstrated more specificity: smaller feedback perturbations evoked one size of response, while larger feedback perturbations elicited a larger response. P2 amplitudes increased with increases in the feedback perturbation magnitude. Moreover, a reliable relationship existed between vocal response magnitude and P2 amplitude: vocal response magnitude and P2 amplitude increased in response to perturbations between 50 and 250 cents, and then decreased in response to larger perturbations. ERPs allow us to hypothesize the stages of processing. Results will be discussed with respect to perceptual and production thresholds and implications for speech motor control.
Sensorimotor integration during human self-vocalization: Insights from invasive electrophysiology
Authors: Greenlee Jeremy , Behroozmand Roozbeh , Narayanan Nandakumar , Kingyon Jonathan R. , Larson Charles , Oya Hiroyuki , Kawasaki Hiroto , Howard Matthew A.
Published: May 2013

Effective human speech requires the neural integration of ongoing vocal production with the auditory and somatosensory feedback signals that are produced. We are using invasive electrophysiology techniques in patient volunteers undergoing neurosurgical treatment in order to gain insights into these mechanisms and underlying neural circuits. By using multi-contact electrode arrays chronically implanted over the perisylvian temporal lobe auditory cortex (e.g., area PLST) and the inferior frontal gyrus (IFG), we can examine local field potentials and frequency-specific responses from cortical areas important for both vocal production and speech sound processing. Our initial studies have found that during self-vocalization, focal areas within higher order auditory cortex on the superior temporal gyrus (STG) show response modulation compared to the responses of the same areas during passive listening. Manipulation of the auditory feedback that a speaker receives during vocalization (e.g., pitch-shifted or delayed auditory feedback) leads to further modulation of these PLST sites. Measures of functional connectivity including electrical stimulation tract tracing or phase-synchrony analysis demonstrate that portions of PLST are functionally connected to regions of the IFG. These findings support forward models for vocal control in which efference copies of premotor cortex activity modulate sub-regions of auditory cortex.
Perceptual sensitivity to a model of the source spectrum
Authors: Garellek Marc , Samlan Robin A. , Kreiman Jody E. , Gerratt Bruce R.
Published: May 2013

A psychoacoustic model of the source spectrum has been proposed in which four spectral slope parameters describe perception of overall voice quality: H1-H2 (the difference in amplitude between the first and second harmonics), H2-H4, H4-2000 Hz (i.e., the harmonic nearest 2000 Hz), and 2000–5000 Hz. The goals of this study are to evaluate perceptual sensitivity in the mid-to-high frequency range of the model and determine how sensitivity to one parameter varies as a function of another. To determine listener sensitivity to slope changes for each parameter, just-noticeable differences were obtained for series of stimuli based on synthetic copies of one male and one female voice. Twenty listeners completed an adaptive up-down paradigm. To provide a baseline of listener sensitivity to each spectral slope parameter, the synthetic voices were manipulated so that spectral slope varied by 0.5 dB increments for each parameter while other parameters remained constant. We then assessed how listener sensitivity to a given harmonic slope parameter changes when the others covary. These results will help assess the validity of the model and determine what sources of cross-voice variability in spectral configuration are perceptible.
A physiologically and perceptually motivated voice source model
Authors: Chen Gang , Garellek Marc , Kreiman Jody , Gerratt Bruce R. , Alwan Abeer
Published: May 2013

Many glottal source models have been proposed, but none has been systematically validated perceptually. Our previous work showed that model fitting of the negative peak of the flow derivative is the most important predictor of perceptual similarity to the target voice. In this study, a new voice source model motivated by high-speed laryngeal videoendoscopy is proposed to capture perceptually-important source shape aspects. Six voice source models (the proposed model, two previous models developed at UCLA, as well as the Fujisaki-Ljungkvist, Liljencrants-Fant, and Rosenberg models) were fitted to 40 natural voices obtained by inverse filtering and analysis-by-synthesis (AbS). We generated synthetic copies of the voices using each modeled source pulse, with all other parameters held constant, and then conducted a visual sort-and-rate task in which listeners assessed the extent of perceived match between the original natural voice samples and each copy. Model fitting results showed that the proposed model provides a more accurate fitting to the AbS-derived source than the other models. Perceptual experiments showed that the proposed model provides a close match to the original natural voice. Perceptual studies examining the extent to which each model matches the target tokens will also be reported. [Work supported by NSF grant IIS-1018863 and NIH/NIDCD grant DC01797.]
The quantal larynx revisited
Authors: Moisik Scott , Gick Bryan
Published: May 2013

Quantal effects signify nonlinear relations in the properties of speech sounds, traditionally emphasizing articulatory-acoustic relations [Stevens, J. Phonet. 17, 3–45 (1989)]; these relations hold important clues to how continuous phonetic parameters map onto discrete phonological categories. Stevens described quantal states in laryngeal speech function, showing how the vocal fold abduction-adduction continuum can be partitioned into breathy, modal, and pressed phonatory quanta. This account, however, relies on a one-dimensional conceptualization of the larynx, which recent developments in laryngeal phonetic theory reveal to be inadequate [Edmondson and Esling, Phonology 23, 157–191 (2006)]: a more realistic model must include the epilarynx. We reopen the issue of quantal laryngeal speech behavior in the context of recent research demonstrating quantal biomechanical properties in labial articulation [Gick et al., Can. Acoust. 39, 178–179 (2011)]. Our “whole larynx” approach [Moisik and Esling, ICPhS, 1406–1409 (2011)] countenances epilaryngeal influence on laryngeal articulatory and phonatory possibilities through quantal biomechanical and aero-mechanical effects. We demonstrate, through computer simulation, three novel cases of laryngeal quantality: (1) vocal-ventricular interaction in glottal stop, glottalization, and laryngealization; (2) aryepiglotto-epiglottal stricture in pharyngeal consonants; (3) epilaryngeal predisposition for growl-like or harsh phonation.
Individual control of singing voice based on cepstrum manipulation
Authors: Ikeda Kenji , Nakano Kota , Morise Masanori , Nakayama Masato , Nishiura Takanobu
Published: May 2013

Desktop music (DTM) software is used to synthesize various instrumental sounds, whereas it was difficult to synthesize the natural singing voice because the singing voice is more complicated than other instrumental sounds. In the past, it had been object that we output more natural singing voice by analyzing the singing voice and extracting the spectrum envelope with high accuracy. Recently, since the algorithm is improved, the singing voice synthesis software is used. In the conventional method, it had been focused changing the original voice personality by controlling some parameters of spectrum envelope. However, the method can synthesize the singing voice by only particular voice personality. The quality of the synthesized singing voice also depends on accurate control of voice personality. In this study, we attempt to control user’s impression directly and investigate the control method that is focused on the singer's individuality in the singing voice. In this paper, we propose a voice personality control method based on mapping the timbre of target singer in the cepstrum domain and demonstrate the effectiveness of the proposed method. As a result of subjective experiments, we confirmed that the proposed method can control the voice personality of singers with high quality.
Modeling vocal fold asymmetries with coupled Van der Pol oscillators
Authors: Lucero Jorge C. , Schoentgen Jean
Published: May 2013

Models of the glottal sound source are being developed to extend a recent synthesizer of disordered voices [Fraj et al., J. Acoust. Soc. Am. 132, 2603–2615 (2012)]. The synthesizer was based on a nonlinear wave-shaping algorithm, which generates a glottal excitation to a concatenated-tube representation of the trachea and vocal tract. The purpose of the present work is to incorporate a physics-based model of the vibrating vocal folds in order to increase the anatomical fidelity of the synthesizer. Further, the model will permit to characterize left-right fold asymmetries and explore the effect of those asymmetries on the resultant vocal timbre. In this report, the vocal folds are represented as a system of two coupled Van der Pol oscillators with noise terms and a detuning factor between their natural frequencies. Regions of phase locked and unlocked oscillations are determined and illustrated with bifurcation diagrams. Also, the effect of frequency detuning on the resultant frequency jitter is analyzed. The results are discussed in terms of their implications for modeling abnormal vocal fold behavior. [Work supported by CNPq (Brazil) and FNRS (Belgium).]
Disruptive effect of unattended noise-vocoded speech on recall of visually presented digits: Interaction between the number of frequency bands and languages
Authors: Ueda Kazuo , Nakajima Yoshitaka , Doumoto Kana , Ellermeier Wolfgang , Kattner Florian
Published: May 2013

To assess the effects of degraded irrelevant speech on the serial recall of visually presented digits, noise-vocoded speech was generated in Japanese and German. Effects of the participants' native language were also examined by studying 40 Japanese and 40 German listeners. The number of frequency bands used in vocoding and the language (native or not) the irrelevant sound was derived from affected performance significantly. The participants' native language had a greater disruptive effect than the non-native language, particularly in conditions in which intelligibility was moderate. Speech sounds appear to have been processed automatically although the participant was instructed to neglect them. This must have required some amount of cognitive resources, which could have been used for the recall task otherwise. This automatic interference was stronger when the native language was used, probably because it contained perceptual cues that were more difficult to degrade.
Separation of moving ship striation patterns using physics-based filtering
Authors: Le Gall Yann , Bonnel Julien
Published: May 2013

When a ship is moving toward an acoustic receiver in an oceanic waveguide, the time-frequency representation of the recorded signal exhibits a striation pattern that can be useful in numerous applications such as ship localization or geoacoustic inversion. If there are many ships, the striation patterns add up and they must be separated if one wants to study them separately. In this paper, a physics-based filtering scheme for passive underwater acoustics has been developed. The algorithm allows separating the time-frequency striations of two different moving ships. The proposed method considers filtering the 2D Fourier transform of the received spectrogram. The filter design is based on the waveguide invariant principle and on some a priori knowledge on the oceanic waveguide. The noise nature on the spectrogram is taken into account by introducing a nonlinearity to the filtering scheme. The algorithm thus corresponds to a nonlinear homomorphic filter. The method is validated on both simulated data and experimental marine data. This filtering scheme offers good prospects for all applications using ship noise and a single receiver.
Comparison of two-dimensional axial-symmetric and two-in-one-half dimensional Green's function methods for three-dimensional shallow water acoustic propagation using finite element methods
Authors: Goldsberry Benjamin M. , Isakson Marcia J.
Published: May 2013

In shallow water acoustic propagation, performing a fully three-dimensional finite element model is currently unfeasible due to difficulty in implementation and limits in computational power. Therefore, alternative representations of the 3D acoustic field are sought. Two promising methods to represent the 3D field are a locally invariant, 2.5D Green’s Function kernel, and a 2D axial-symmetric reduction of the 3D Helmholtz equation. When a spherical source is used, azimuthal symmetry of the acoustic propagation is assumed, and these two methods can be compared in 2D planes of the 3D field. Because the 2.5D method takes more computational time than the axial-symmetric method, the accuracy of the pressure field are compared to see if the axial-symmetric method can be used in place of the 2.5D method. First, the two methods are compared for a flat ocean surface with stratified media. Then, a wedge-shaped ocean surface is considered, and the two methods are compared with 2D PE solutions. These comparisons will show if the axial-symmetric method produces similar results to the 2.5D method, and if so, under which geometrical and physical situations the axial-symmetric method can be used in place of the 2.5D method. [Work sponsored by the Office of Naval Research, Ocean Acoustics.]
Construction and optimization techniques for high order schemes for the two-dimensional wave equation
Authors: Bilbao Stefan , Hamilton Brian
Published: May 2013

With the advent of high performance parallel computing, audio rate room auralization using finite difference time domain (FDTD) methods is becoming possible in a reasonable computation time. Yet, there are still deficiencies in the methods, which are used for this purpose, particularly with regard to minimizing numerical dispersion over the full range of audible frequencies. This paper is concerned with construction techniques for families of methods for the test case of the 2D wave equation. Such methods are explicit, can be of very high accuracy, and operate over a small local stencil. Such schemes can be attractive in a parallel computation environment. As such methods will depend, invariably, on a set of free parameters, including the Courant number, a major concern is optimization. The remainder of this paper approaches the problem of setting up such an optimization problem in terms of various constraints and a suitable cost function. Some of the constraints follow from consistency, stability, isotropy, and accuracy of the resulting scheme, and others from perceptual considerations peculiar to audio. Simulation results will be presented.
Hexagonal vs. rectilinear grids for explicit finite difference schemes for the two-dimensional wave equation
Authors: Hamilton Brian , Bilbao Stefan
Published: May 2013

Finite difference schemes for the 2-D wave equation operating on hexagonal grids and the accompanying numerical dispersion properties have received little attention in comparison to schemes operating on rectilinear grids. This paper considers the hexagonal tiling of the wavenumber plane in order to show that the hexagonal grid is a more natural choice to emulate the isotropy of the Laplacian operator and the wave equation. Performance of the 7-pt scheme on a hexagonal grid is better than previously reported as long as the correct stability limit and tiling of the wavenumber plane are taken into account. Numerical dispersion is analyzed as a function of temporal frequency to demonstrate directional cutoff frequencies. A comparison to 9-pt compact explicit schemes on rectilinear grids is presented using metrics relevant to acoustical simulation. It is shown that the 7-pt hexagonal scheme has better computational efficiency than parameterized 9-pt compact explicit rectilinear schemes and that the error remains isotropic to fourth-order. Simulation results are presented.
Acoustic invasion: How invasive species can impact native species acoustic niche?
Authors: Both Camila , Grant Taran
Published: May 2013

The effects of invasive species on native taxa due to direct predation, food, and space competition, and disease transmission are well documented. However, the effects of acoustic invaders on animal communication have not been explored. We simulated an invasion of the acoustic niche by exposing calling native male white-banded tree frogs (Hypsiboas albomarginatus, harmonics at 60–1430 Hz and 2720–2780 Hz or 2280–2850 Hz) to recorded calls of the invasive American bullfrog (Lithobates catesbeianus, frequencies from 90 to >4000 Hz) at a non-invaded site in the Brazilian Atlantic Forest. In response, tree frogs immediately shifted calls to significantly higher frequencies. In the post-stimulus period, they continued to use higher frequencies and also decreased signal duration. Tree frogs did not change calling rate or inter-call interval. Acoustic signals are the primary basis of mate selection in many anurans, and such changes could negatively affect the reproductive success of native species. The effects of bullfrog vocalizations on acoustic communities are expected to be especially severe due to their broad frequency band, which masks the calls of multiple species simultaneously. These results show that invasive species could affect native species by interfering in their acoustic niche.
Acoustic scattering from a water-filled cylindrical shell: Mode identification and interpretation via finite element and analytical models
Authors: Espana Aubrey L. , Williams Kevin L. , Plotnick Daniel S. , Marston Philip L.
Published: May 2013

Understanding the physics governing the interaction of sound with targets in an underwater environment is essential to improving upon existing target detection and classification algorithms. Simple models are viable tools for meaningful interpretation of scattering results. To illustrate this, two modeling techniques are employed to study the acoustic scattering from a water-filled cylindrical shell. The first model is a hybrid 2-D/3-D finite element (FE) model, whereby the scattering in close proximity to the target is handled via a 2-D axisymmetric FE model, and the subsequent 3-D propagation to the farfield is determined via a Helmholtz integral. This model is characterized by the decomposition of the fluid pressure and its derivative in a series of azimuthal Fourier modes, a technique that has previously facilitated mode identification [Espana et al., J. Acoust. Soc. Am. 130, 2332 (2011)]. The second is an analytical solution for an infinitely long cylindrical shell, coupled with a simple approximation that converts the results to an analogous finite length form function. These two model results, when examined together on a mode-by-mode basis, offer visualization of the mode dynamics and the ability to distinguish the different physics driving the target response (i.e., structural modes versus water-waveguide modes). [Work supported by ONR.]
Clustering of acoustic fish features tracked by broadband split-beam echo sounder
Authors: Ito Masanori , Matsuo Ikuo , Imaizumi Tomohito , Akamatsu Tomonari , Wang Yong , Nishimori Yasushi
Published: May 2013

Monitoring fish species and amount with acoustical instruments is a challenging problem to survey fish resources in the ocean. Broadband split-beam echo sounder was useful to observe individual fish behavior in schools. Echoes from fish schools were measured from an anchored vessel for several hours. Echo signals were gathered into one block within a certain depth and a period of time and analyzed to track individual fish in the schools. Target strength was calculated from the individual fish echo and associated with tilt angle which could be estimated by using the tracking result. Feature in each block was statistically calculated by averaging target strengths according to the tilt angles. The blocks of the signals were clustered by K-means method with the features and divided into some clusters. The distribution of the clusters in time and depth was investigated. It appeared that the distributions of the clusters were dependent on both time and depth. Clustering of the features would be effective to monitor diversity of fish in the ocean. [Research supported by JST, CREST.]
Improvement of an intravascular ultrasound elasticity modulus imaging approach for detecting vulnerable atherosclerotic plaques
Authors: Keshavarz-Motamed Zahra , Le Floc'h Simon , Ohayon Jacques , Cloutier Guy
Published: May 2013

Atherosclerotic plaque rupture is the major cause of acute coronary syndrome, myocardial infarction, and stroke in the western world. Stress concentration is recognized to be a good indicator of vulnerable plaques (VP). The Lagrangian speckle model estimator (LSME) for vascular ultrasound elastography, developed by our group, provides the strain field within the plaque. However, evaluation of the stress field relies on a precise identification of the mechanical properties of plaque components. As a response to this need, our group recently developed an approach called imaging modulography (iMOD). iMOD uses a continuum-mechanics-based segmentation method and the inverse finite-element method to reconstruct elasticity maps (or modulograms) of atheroma plaques based on the radial strain field calculated by the LSME. The present theoretical study was designed to further develop segmentation and optimization procedures of iMOD to incorporate both radial and shear components of the strain tensor. Simulated IVUS images of coronary lesions with known material properties and known stress fields were used to validate the new iMOD algorithm and assess its robustness and performance in detection and quantification of VPs. The results demonstrate promising beneﬁts of the new optimized iMOD-LSME clinical imaging method for VP detection.
Sound transmission in a simple model of the ear canal and tympanic membrane
Authors: Gonzalez-Herrera Antonio , Wattamwar Kapil , Bergevin Christopher , Olson Elizabeth S.
Published: May 2013

The classic picture of middle ear (ME) transmission has the tympanic membrane (TM) as a piston and the ME space as a vacuum. However, the TM moves in a complex wavy pattern and modern theories link this behavior to the ME’s broadband transmission [e.g., Fay et al, Proc. Natl. Acad. Sci. U.S.A. (2006), Parent and Allen, J. Acoust. Soc. Am. (2007)]. Furthermore, Rabbitt [J. Acoust. Soc. Am. (1990)] predicted that the TM radiated considerable sound pressure into the ME space that could in return affect TM motion. This study explores these ideas with a simple model, using a tube terminated with a plastic membrane to model the EC and TM. We measured membrane motion via laser interferometry, and pressure (on both sides) via micro-sensors that allowed positioning very close to the membrane (10 micrometers) without disturbance. We made a finite element model of the system to complement the experimental results. The theoretical results show the interaction of acoustic and mechanical resonances, and both theoretical and experimental results show strong transmission of sound through the membrane at some of its resonant frequencies.
Pole-zero modeling of the middle ear based on acoustic reflectance measurements
Authors: Robinson Sarah , Allen Jont
Published: May 2013

Fitting poles and zeros to complex acoustic reflectance (CAR) data using a “rational approximation method” [Gustavsen and Semlyen (1999)] allows for a precise parameterization of complex real-ear measurements. CAR is measured using a foam-tipped probe sealed in the ear canal, containing a microphone and receiver (i.e., MEPA3 system, Mimosa Acoustics). From the complex pressure response to a broadband stimulus, the acoustic impedance and reflectance of the middle ear can be calculated as functions of frequency. The goal of this work is to establish a quantitative connection between the fitted pole-zero locations and underlying physical properties of the CAR and impedance of the middle ear. It was found that (1) the contribution of the ear canal may be approximated as the lossless all-pass component of the factored reflectance fit, (2) individual CAR magnitude variations for normal middle ears in the 1 to 4 kHz range give rise to closely placed pole-zero pairs, and (3) the locations of the poles and zeros in the s-plane may differ between normal and pathological middle ears. Pole-zero fitting allows for concise characterization of individual CAR measurements, providing a foundation for modeling individual and pathological variations of middle ears.
Inspectability of interfaces between composite and metallic layers using ultrasonic interface waves
Authors: Gardner Michael D. , Rose Joseph L. , Koudela Kevin L. , Moose Clark A.
Published: May 2013

The interface between an anisotropic composite material and a metallic material is inspected non-destructively for disbonded regions using ultrasonic guided waves. The material properties of the composite and metal have been tailored to demonstrate their effect on inspectability. The material properties have been designed to be either favorable or unfavorable to the existence of propagating Stoneley waves. Stoneley waves can exist because the layer thicknesses are large enough compared to the wavelength to be considered half-spaces. The existence of Stoneley waves between generally anisotropic materials depends on the elastic constants and densities in a complicated way. The range of material properties that allow Stoneley waves is small; however, when the vertically polarized shear wave speeds are similar in the two materials, the existence of Stoneley waves is generally possible. If the conditions do not strictly allow Stoneley waves, other interface waves can still exist such as leaky waves. Disbonds are inserted into the materials before bonding and are inspected using interface waves. Sensitivity to disbonds is determined and thus inspectability is demonstrated for cases that are favorable and unfavorable to Stoneley waves. Both numerical and physical experimental results are shown.
Case studies of casing inspection with multi-functional ultrasonic imaging logging tool
Authors: Sun Zhifeng , Chen Honghai , Liu Xien
Published: May 2013

The multi-functional ultrasonic imaging logging tool can provide casing inspection and cement bonding evaluation by using ultrasonic pulse echo technique. The casing’s internal conditions can be inspected from echo amplitude and transit time curves. The casing thickness and the cement impedance can be calculated from resonance frequency and resonance decay. The paper describes three well cases histories of casing inspection in detail with this instrument. The first case reports the evaluation of perforation interval in the cased hole; hole enlargement of perforation interval and perforations can be seen from echo amplitude and casing internal radius imaging curves. In the second case, we cannot distinguish corrosion or deposits in the casing surface from the echo amplitude and transit time curves, but casing thickness imaging curve characterize some slight corrosion. Finally, the last case history describes evaluation of casing mechanical wear in a deviated well; casing thickness imaging curve shows mechanical wear is caused by logging instrument in low side well. All cases shows that the multi-functional ultrasonic imaging logging tool can provide both quantitative and qualitative evaluation and diagnosis of casing problems.
Cylindrical cyclic acoustic imaging with a Bayesian approach for cyclostationary sources reconstruction
Authors: Personne Sebastien , Antoni Jerome , Chazot Jean Daniel
Published: May 2013

Standard acoustic imaging techniques, such as beamforming or near acoustical holography, are now widely used in engineering contexts. However, large arrays of microphones are sometimes required to have a good resolution. Besides new challenges arise, particularly in the field of non stationary sources, which need to be identified and solved. Cyclostationary sound sources, a specific kind of non stationary signals, are characterized by statistical properties evolving periodically in time. In practice, the first-order statistical properties contain some periodic components while the second orders may be random with a periodic flow of energy. The present work tackles the acoustic imaging of cyclostationary sources with a scanning microphone, i.e., without any array. Cylindrical surfaces, adapted to standard rotating machines, are considered. The reconstruction difficulty of acoustic sources from discrete measurements is addressed here thanks to the cyclostationary properties. A cyclic sound field is hence extracted from the discrete measurements. Finally, a Bayesian formulation, gathering both physical and probabilistic information on this inverse problem, is used to back propagate the sound over the radiating surface.