bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of oil price shocks on industrial production: evidence from some oil‐exporting countries
Authors: Mehrara Mohsen , Sarem Mehdi
Published: December 2009

This paper examines the effects of oil price shocks on industrial production in three oil‐exporting countries, namely Iran, Saudi Arabia and Indonesia using annual data for the period 1970–2005. First, the Gregory and Hansen cointegration technique, allowing for the presence of potential structural breaks in data, is applied to empirically examine the long‐run co‐movement between oil price and output. Second, we test whether different measures of oil price shocks, including non‐linear or asymmetric ones, Granger‐cause output. The results indicate a strong causality from oil price shocks to output growth for Iran and Saudi Arabia. Moreover, the oil prices–output relationship in these two countries appears more significant when asymmetric specifications are used to model the relationship between variables. In the case of Indonesia, however, none of the oil proxies have any significant effect on output both in the short and long run. The results confirm the relatively successful experience of countries such as Indonesia in the diversification of the real sector to minimise the harmful effects of oil booms and busts.
Underlying consumer preferences and their contribution to energy demand
Authors: Adeyemi Olutomi I. , Broadstock David C.
Published: December 2009

The demand for energy is not simply a function of price and income, but can be shown to also be a function of the underlying energy demand trend (UEDT). The UEDT not only captures behavioural responses to non‐fiscal instruments, including technological change, but also encapsulates attitudinal responses/changes in demand that might result, for instance, from increased public awareness of how environmentally damaging energy use can be; hence, reflecting underlying consumer preferences.

This study estimates a longitudinal econometric model for the aggregate demand functions of a sample of 17 Organisation for Economic Co‐operation and Development countries for the period 1960–2005. This approach to modelling will enable UEDTs to be observed for each of the countries, as well as normal price and income elasticities. The model results will provide an indication of the extent to which price/income‐based instruments can be used to reduce the demand for energy, as well as indicating the extent to which consumers have responded to non‐price/income instruments.
Optimal Tuner Selection for Kalman Filter-Based Aircraft Engine Performance Estimation
Authors: Simon Donald L. , Garg Sanjay
Published: December 2009

A linear point design methodology for minimizing the error in on-line Kalman filter-based aircraft engine performance estimation applications is presented. This technique specifically addresses the underdetermined estimation problem, where there are more unknown parameters than available sensor measurements. A systematic approach is applied to produce a model tuning parameter vector of appropriate dimension to enable estimation by a Kalman filter, while minimizing the estimation error in the parameters of interest. Tuning parameter selection is performed using a multivariable iterative search routine that seeks to minimize the theoretical mean-squared estimation error. This paper derives theoretical Kalman filter estimation error bias and variance values at steady-state operating conditions, and presents the tuner selection routine applied to minimize these values. Results from the application of the technique to an aircraft engine simulation are presented and compared with the conventional approach of tuner selection. Experimental simulation results are found to be in agreement with theoretical predictions. The new methodology is shown to yield a significant improvement in on-line engine performance estimation accuracy.
Near resonant bubble acoustic cross-section corrections, including examples from oceanography, volcanology, and biomedical ultrasound
Authors: Ainslie Michael A. , Leighton Timothy G.
Published: December 2009

The scattering cross-section σs of a gas bubble of equilibrium radius R0 in liquid can be written in the form σs=4πR02∕[(ω12∕ω2−1)2+δ2], where ω is the excitation frequency, ω1 is the resonance frequency, and δ is a frequency-dependent dimensionless damping coefficient. A persistent discrepancy in the frequency dependence of the contribution to δ from radiation damping, denoted δrad, is identified and resolved, as follows. Wildt’s [Physics of Sound in the Sea (Washington, DC, 1946), Chap. 28] pioneering derivation predicts a linear dependence of δrad on frequency, a result which Medwin [Ultrasonics 15, 7–13 (1977)] reproduces using a different method. Weston [Underwater Acoustics, NATO Advanced Study Institute Series Vol. II, 55–88 (1967)], using ostensibly the same method as Wildt, predicts the opposite relationship, i.e., that δrad is inversely proportional to frequency. Weston’s version of the derivation of the scattering cross-section is shown here to be the correct one, thus resolving the discrepancy. Further, a correction to Weston’s model is derived that amounts to a shift in the resonance frequency. A new, corrected, expression for the extinction cross-section is also derived. The magnitudes of the corrections are illustrated using examples from oceanography, volcanology, planetary acoustics, neutron spallation, and biomedical ultrasound. The corrections become significant when the bulk modulus of the gas is not negligible relative to that of the surrounding liquid.
Under-ice noise generated from diamond exploration in a Canadian sub-arctic lake and potential impacts on fishes
Authors: Mann D. , Cott P. , Horne B.
Published: December 2009

Mineral exploration is increasing in Canada, particularly in the north where extensive diamond mining and exploration are occurring. This study measured the under-ice noise produced by a variety of anthropogenic sources (drilling rigs, helicopters, aircraft landing and takeoff, ice-road traffic, augers, snowmobiles, and chisels) at a winter-based diamond exploration project on Kennady Lake in the Northwest Territories, Canada to infer the potential impact of noise on fishes in the lake. The root-mean-square noise level measured 5 m from a small diameter drill was approximately 46 dB greater (22 kHz bandwidth) than ambient noise, while the acoustic particle velocity was approximately 40 dB higher than ambient levels. The loudest sounds at the exploration site were produced by ice cracking, both natural and during landing and takeoff of a C130 Hercules aircraft. However, even walking on the snow above the ice raised ambient sound levels by approximately 30 dB. Most of the anthropogenic sounds are likely detectable by fishes with hearing specializations, such as chubs and suckers. Other species without specialized hearing adaptations will detect these sounds only close to the source. The greatest potential impact of noise from diamond exploration is likely to be the masking of sounds for fishes with sensitive hearing.
Combination of masking releases for different center frequencies and masker amplitude statistics
Authors: Epp Bastian , Verhey Jesko L.
Published: December 2009

Several masking experiments have shown that the auditory system is able to use coherent envelope fluctuations of the masker across frequency within one ear as well as differences in interaural disparity between signal and masker to enhance signal detection. The two effects associated with these abilities are comodulation masking release (CMR) and binaural masking level difference (BMLD). The aim of the present study was to investigate the combination of CMR and BMLD. Thresholds for detecting a sinusoidal signal were measured in a flanking-band paradigm at three different signal frequencies. The masker was presented diotically, and various interaural phase differences (IPDs) of the signal were used. The masker components were either multiplied or Gaussian narrowband noises. In addition, a transposed stimulus was used to increase the BMLD at a high signal frequency. For all frequencies and masker conditions, thresholds decreased as the signal IPD increased and were lower when the masker components were comodulated. The data show an addition of the monaural and binaural masking releases in decibels when masker conditions with and without comodulation and the same spectrum were compared.
A stochastic response surface formulation of acoustic propagation through an uncertain ocean waveguide environment
Authors: Finette Steven
Published: December 2009

Stochastic basis expansions are applied to formulate and solve the problem of including uncertainty in numerical models of acoustic wave propagation within ocean waveguides. As an example, a constrained least-squares approach is used to estimate the intensity of an acoustic field whose waveguide environment has uncertainty in both source depth and sound speed. The mean intensity, a second moment of the field, and its probability distribution are computed and compared with independent Monte-Carlo computations of these quantities. Very good agreement is obtained, indicating the potential of stochastic basis expansions for describing multiple sources of uncertainty and their effect on acoustic propagation.
Analysis and design of gammatone signal models
Authors: Strahl Stefan , Mertins Alfred
Published: December 2009

An established model for the signal analysis performed by the human cochlea is the overcomplete gammatone filterbank. The high correlation of this signal model with human speech and environmental sounds [E. Smith and M. Lewicki, Nature (London) 439, 978–982 (2006)], combined with the increased time-frequency resolution of sparse overcomplete signal models, makes the overcomplete gammatone signal model favorable for signal processing applications on natural sounds. In this paper a signal-theoretic analysis of overcomplete gammatone signal models using the theory of frames and performing bifrequency analyses is given. For the number of gammatone filters M≥100 (2.4 filters per equivalent rectangular bandwidth), a near-perfect reconstruction can be achieved for the signal space of natural sounds. For signal processing applications like multi-rate coding, a signal-to-alias ratio can be used to derive decimation factors with minimal aliasing distortions.
Cross-dialectal variation in formant dynamics of American English vowels
Authors: Fox Robert Allen , Jacewicz Ewa
Published: December 2009

This study aims to characterize the nature of the dynamic spectral change in vowels in three distinct regional varieties of American English spoken in the Western North Carolina, in Central Ohio, and in Southern Wisconsin. The vowels /ɪ, ε, e, æ, aɪ/ were produced by 48 women for a total of 1920 utterances and were contained in words of the structure /bVts/ and /bVdz/ in sentences which elicited nonemphatic and emphatic vowels. Measurements made at the vowel target (i.e., the central 60% of the vowel) produced a set of acoustic parameters which included position and movement in the F1 by F2 space, vowel duration, amount of spectral change [measured as vector length (VL) and trajectory length (TL)], and spectral rate of change. Results revealed expected variation in formant dynamics as a function of phonetic factors (vowel emphasis and consonantal context). However, for each vowel and for each measure employed, dialect was a strong source of variation in vowel-inherent spectral change. In general, the dialect-specific nature and amount of spectral change can be characterized quite effectively by position and movement in the F1 by F2 space, vowel duration, TL (but not VL which underestimates formant movement), and spectral rate of change.
Effects of syllable-final segment duration on the identification of synthetic speech continua by birds and humans
Authors: Welch Thomas E. , Sawusch James R. , Dent Micheal L.
Published: December 2009

In an attempt to test whether experience with or knowledge of language is necessary to show typical speaking rate effects in the perception of speech, budgerigars (Melopsittacus undulatus) and humans categorized stimuli from the synthetic continua /ba/-/wa/ and /bas/-/was/, with both short and long syllable-final phonemes. This comparative approach aims to shed some light on whether knowledge of language has a role in rate normalization effects, such as using duration information as an indicator of speaking rate in human speech perception. Syllable-final phoneme durations were varied, and were either temporally adjacent to the initial target (CV series) or were nonadjacent (CVC series). The birds were always influenced by syllable-final duration variation in the present experiments and displayed greater boundary shifts than humans. In humans, there was a significant boundary shift observed in the CV series, but there were no effects of duration variation in the final segment in the CVC series. The results from the birds suggest that specialized speech-based principles may not be necessary for explaining findings of grouping speech or speechlike elements in perception.
Relative influence of interaural time and intensity differences on lateralization is modulated by attention to one or the other cue: 500-Hz sine tones
Authors: Lang Albert-Georg , Buchner Axel
Published: December 2009

When interaural time differences and interaural intensity differences are set into opposition, the measured trading ratio depends on which cue is adjusted by the listener. In an earlier article [Lang, A.-G., and Buchner, A., J. Acoust. Soc. Am. 124, 3120–3131 (2008)], four experiments showed that the perceived localization of a broad band sound for which differences in one cue were compensated by differences in the other cue such that the sound seemed to originate from a central position shifted back toward the location from which the sound appeared to originate before the adjustment. It was argued that attention shifted toward the effect of the to-be-adjusted cue during the compensation task, leading to an increased weighting of the to-be-adjusted cue. The use of broadband stimuli raises the question whether the “shift-back effect” was caused by attentional shifts to the effect of the to-be-adjusted binaural cue or by attention shifts to the particular frequency range which is most important for localizations based on the to-be-adjusted cue. Two experiments are reported in which sine tones of 500Hz were used instead of broadband sounds. The shift-back effect could still be observed, supporting our original hypothesis. A control experiment showed that participants had accurate representations of the critical central position.
Perceptual adaptation and intelligibility of multiple talkers for two types of degraded speech
Authors: Bent Tessa , Buchwald Adam , Pisoni David B.
Published: December 2009

Talker intelligibility and perceptual adaptation under cochlear implant (CI)-simulation and speech in multi-talker babble were compared. The stimuli consisted of 100 sentences produced by 20 native English talkers. The sentences were processed to simulate listening with an eight-channel CI or were mixed with multi-talker babble. Stimuli were presented to 400 listeners in a sentence transcription task (200 listeners in each condition). Perceptual adaptation was measured for each talker by comparing intelligibility in the first 20 sentences of the experiment to intelligibility in the last 20 sentences. Perceptual adaptation patterns were also compared across the two degradation conditions by comparing performance in blocks of ten sentences. The most intelligible talkers under CI-simulation also tended to be the most intelligible talkers in multi-talker babble. Furthermore, listeners demonstrated a greater degree of perceptual adaptation in the CI-simulation condition compared to the multi-talker babble condition although the extent of adaptation varied widely across talkers. Listeners reached asymptote later in the experiment in the CI-simulation condition compared with the multi-talker babble condition. Overall, these two forms of degradation did not differ in their effect on talker intelligibility, although they did result in differences in the amount and time-course of perceptual adaptation.
Vibration absorption using non-dissipative complex attachments with impacts and parametric stiffness
Authors: Roveri N. , Carcaterra A. , Akay A.
Published: December 2009

Studies on prototypical systems that consist of a set of complex attachments, coupled to a primary structure characterized by a single degree of freedom system, have shown that vibratory energy can be transported away from the primary through use of complex undamped resonators. Properties and use of these subsystems as by energy absorbers have also been proposed, particularly using attachments that consist of a large set of resonators. These ideas have been originally developed for linear systems and they provided insight into energy sharing phenomenon in large structures like ships, airplanes, and cars, where interior substructures interact with a master structure, e.g., the hull, the fuselage, or the car body. This paper examines the effects of nonlinearities that develop in the attachments, making them even more complex. Specifically, two different nonlinearities are considered: (1) Those generated by impacts that develop among the attached resonators, and (2) parametric effects produced by time-varying stiffness of the resonators. Both the impacts and the parametric effects improve the results obtained using linear oscillators in terms of inhibiting transported energy from returning to the primary structure. The results are indeed comparable with those obtained using linear oscillators but with special frequency distributions, as in the findings of some recent papers by the same authors. Numerically obtained results show how energy is confined among the attached oscillators.
Analysis of pausing behavior in spontaneous speech using real-time magnetic resonance imaging of articulation
Authors: Ramanarayanan Vikram , Bresch Erik , Byrd Dani , Goldstein Louis , Narayanan Shrikanth S.
Published: December 2009

It is hypothesized that pauses at major syntactic boundaries (i.e., grammatical pauses), but not ungrammatical (e.g., word search) pauses, are planned by a high-level cognitive mechanism that also controls the rate of articulation around these junctures. Real-time magnetic resonance imaging is used to analyze articulation at and around grammatical and ungrammatical pauses in spontaneous speech. Measures quantifying the speed of articulators were developed and applied during these pauses as well as during their immediate neighborhoods. Grammatical pauses were found to have an appreciable drop in speed at the pause itself as compared to ungrammatical pauses, which is consistent with our hypothesis that grammatical pauses are indeed choreographed by a central cognitive planner.
Explosion localization via infrasound
Authors: Szuberla Curt A. L. , Olson John V. , Arnoult Kenneth M.
Published: December 2009

Two acoustic source localization techniques were applied to infrasonic data and their relative performance was assessed. The standard approach for low-frequency localization uses an ensemble of small arrays to separately estimate far-field source bearings, resulting in a solution from the various back azimuths. This method was compared to one developed by the authors that treats the smaller subarrays as a single, meta-array. In numerical simulation and a field experiment, the latter technique was found to provide improved localization precision everywhere in the vicinity of a 3-km-aperture meta-array, often by an order of magnitude.
Broadband cluster transducer for underwater acoustics applications
Authors: Fleming Richard A. G. , Jones Dennis F. , Reithmeier Charles G.
Published: December 2009

A broadband cluster transducer, based on barrel-stave flextensional transducer technology, was designed, built, and tested in air and seawater at Defence R&D Canada—Atlantic. The design goal was to develop a transducer that exhibited a transmitting voltage response of greater than 120 dB∕∕1 μPa-m/V from 1 to 7 kHz and have the potential for beamsteering. Six orthogonal piezoceramic-driven class I barrel-stave transducer elements mounted on a central manifold were wired separately, allowing each to be driven individually or in combination with the other elements. The resonance modes under the following drive conditions were determined from in-air conductance measurements: each of the six elements excited individually as mass-loaded class I flextensionals, three collinear pairs driven separately as class III flextensionals, and all six elements driven in phase simultaneously. The fully-driven cluster was found to have a transmitting voltage response of greater than 120 dB∕∕1 μPa-m/V from 800 Hz to more than 10 kHz and its topology is amenable to beamsteering that is yet to be characterized.
Effects of source-to-listener distance and masking on perception of cochlear implant processed speech in reverberant rooms
Authors: Whitmal Nathaniel A. , Poissant Sarah F.
Published: December 2009

Two experiments examined the effects of source-to-listener distance (SLD) on sentence recognition in simulations of cochlear implant usage in noisy, reverberant rooms. Experiment 1 tested sentence recognition for three locations in the reverberant field of a small classroom (volume=79.2 m3). Subjects listened to sentences mixed with speech-spectrum noise that were processed with simulated reverberation followed by either vocoding (6, 12, or 24 spectral channels) or no further processing. Results indicated that changes in SLD within a small room produced only minor changes in recognition performance, a finding likely related to the listener remaining in the reverberant field. Experiment 2 tested sentence recognition for a simulated six-channel implant in a larger classroom (volume=175.9 m3) with varying levels of reverberation that could place the three listening locations in either the direct or reverberant field of the room. Results indicated that reducing SLD did improve performance, particularly when direct sound dominated the signal, but did not completely eliminate the effects of reverberation. Scores for both experiments were predicted accurately from speech transmission index values that modeled the effects of SLD, reverberation, and noise in terms of their effects on modulations of the speech envelope. Such models may prove to be a useful predictive tool for evaluating the quality of listening environments for cochlear implant users.
Effects of sea-surface conditions on passive fathometry and bottom characterization
Authors: Means Steven L. , Siderius Martin
Published: December 2009

Recently, a method has been developed that exploits the correlation properties of the ocean’s ambient noise to measure water depth (a passive fathometer) and seabed layering [M. Siderius et al., J. Acoust. Soc. Am. 120, 1315–1323 (2006)]. This processing is based on the cross-correlation between the surface noise and the echo return from the seabed. To quantitatively study the dependency between processing and environmental factors such as wind speed, measurements were made using a fixed hydrophone array while simultaneously characterizing the environment. The measurements were made in 2006 in the shallow waters (25m) approximately 75km off the coast of Savannah, GA. A Navy tower about 100m from the array was used to measure wind speed and to observe the sea-surface using a video camera. Data were collected in various environmental conditions with wind speeds ranging from 5to21m∕s and wave heights of 1–3.4m. The data are analyzed to quantify the dependency of passive fathometer results on wind speeds, wave conditions, and averaging times. One result shows that the seabed reflection is detectable even in the lowest wind conditions. Further, a technique is developed to remove the environmental dependency so that the returns estimate seabed impedance.
Forward propagation of time evolving acoustic pressure: Formulation and investigation of the impulse response in time-wavenumber domain
Authors: Grulier Vincent , Paillasseur Sébastien , Thomas Jean-Hugh , Pascal Jean-Claude , Le Roux Jean-Christophe
Published: December 2009

The aim of this work is to continuously provide the acoustic pressure field radiated from nonstationary sources. From the acquisition in the nearfield of the sources of a planar acoustic field which fluctuates in time, the method gives instantaneous sound field with respect to time by convolving wavenumber spectra with impulse response and then inverse Fourier transforming into space for each time step. The quality of reconstruction depends on the impulse response which is composed of investigated parameters as transition frequency and propagation distance. Sampling frequency also affects errors of the practically discrete impulse response used for calculation. To avoid aliasing, the impulse response is low-pass filtered with Chebyshev or Kaiser–Bessel filter. Another approach to implement the impulse response consists of applying an inverse Fourier transform to the theoretical transfer function for propagation. To estimate the performance of each processing method, a simulation test involving several source monopoles driven by nonstationary signals is executed. Some indicators are proposed to assess the accuracy of the temporal signals predicted in a forward plane. The results show that the use of a Kaiser–Bessel filter numerically implemented or that of the inverse Fourier transform can provide the most accurate instantaneous acoustic signals.
Behavioral measures of signal recognition thresholds in frogs in the presence and absence of chorus-shaped noise
Authors: Bee Mark A. , Schwartz Joshua J.
Published: December 2009

Anuran amphibians are superb animal models for investigating the mechanisms underlying acoustic signal perception amid high levels of background noise generated by large social aggregations of vocalizing individuals. Yet there are not well-established methods for quantifying a number of key measures of auditory perception in frogs, in part, because frogs are notoriously difficult subjects for traditional psychoacoustic experiments based on classical or operant conditioning. A common experimental approach for studying frog hearing and acoustic communication involves behavioral phonotaxis experiments, in which patterns of movement directed toward sound sources indicate the subjects’ perceptual experiences. In this study, three different phonotaxis experiments were conducted using the same target signals and noise maskers to compare different experimental methods and analytical tools for deriving estimates of signal recognition thresholds in the presence or absence of “chorus-shaped noise” (i.e., artificial noise with a spectrum similar to that of real breeding choruses). Estimates of recognition thresholds based on measures of angular orientation, response probabilities, and response latencies were quite similar in both two-choice and no-choice phonotaxis tests. These results establish important baselines for comparing different methods of estimating signal recognition thresholds in frogs tested in various masking noise conditions.
Features of across-frequency envelope coherence critical for comodulation masking release
Authors: Buss Emily , Grose John H. , Hall Joseph W.
Published: December 2009

The masking release associated with coherent amplitude modulation of the masker is dependent on the degree of envelope coherence across frequency, with the largest masking release for stimuli with perfectly comodulated envelopes. Experiments described here tested the hypothesis that the effects of reducing envelope coherence depend on the unique envelope features of the on-signal masker as compared to the flanking maskers. Maskers were amplitude-modulated tones (Experiments 1 and 3) or amplitude-modulated bands of noise (Experiment 2), and the signal was a tone; across-frequency masker coherence was manipulated to assess the effects of introducing additional modulation minima in either the on-signal or flanking masker envelopes of otherwise coherently modulated maskers. In all three experiments, the detrimental effect of disrupted modulation coherence was more severe when additional modulation minima were introduced in the flanking as compared to on-signal masker envelopes. This was the case for both ipsilateral and contralateral flanking masker presentations, indicating that within-channel cues were not responsible for this finding. Results are consistent with the interpretation that the cue underlying comodulation masking release is based on dynamic spectral features of the stimulus, with transient spectral peaks at the signal frequency reflecting addition of a signal.
Acoustic emission source location in composite structure by Voronoi construction using geodesic curve evolution
Authors: Gangadharan R. , Prasanna G. , Bhat M. R. , Murthy C. R. L. , Gopalakrishnan S.
Published: December 2009

Conventional analytical/numerical methods employing triangulation technique are suitable for locating acoustic emission (AE) source in a planar structure without structural discontinuities. But these methods cannot be extended to structures with complicated geometry, and, also, the problem gets compounded if the material of the structure is anisotropic warranting complex analytical velocity models. A geodesic approach using Voronoi construction is proposed in this work to locate the AE source in a composite structure. The approach is based on the fact that the wave takes minimum energy path to travel from the source to any other point in the connected domain. The geodesics are computed on the meshed surface of the structure using graph theory based on Dijkstra’s algorithm. By propagating the waves in reverse virtually from these sensors along the geodesic path and by locating the first intersection point of these waves, one can get the AE source location. In this work, the geodesic approach is shown more suitable for a practicable source location solution in a composite structure with arbitrary surface containing finite discontinuities. Experiments have been conducted on composite plate specimens of simple and complex geometry to validate this method.
Acoustic measurement of bubble size in an inkjet printhead
Authors: Jeurissen Roger , van der Bos Arjan , Reinten Hans , van den Berg Marc , Wijshoff Herman , de Jong Jos , Versluis Michel , Lohse Detlef
Published: December 2009

The volume of a bubble in a piezoinkjet printhead is measured acoustically. The method is based on a numerical model of the investigated system. The piezo not only drives the system but it is also used as a sensor by measuring the current it generates. The numerical model is used to predict this current for a given bubble volume. The inverse problem is to infer the bubble volume from an experimentally obtained piezocurrent. By solving this inverse problem, the size and position of the bubble can thus be measured acoustically. The method is experimentally validated with an inkjet printhead that is augmented with a glass connection channel, through which the bubble was observed optically, while at the same time the piezocurrent was measured. The results from the acoustical measurement method correspond closely to the results from the optical measurement.
Otoacoustic emissions in time-domain solutions of nonlinear non-local cochlear models
Authors: Moleti Arturo , Paternoster Nicolò , Bertaccini Daniele , Sisto Renata , Sanjust Filippo
Published: December 2009

A nonlinear and non-local cochlear model has been efficiently solved in the time domain numerically, obtaining the evolution of the transverse displacement of the basilar membrane at each cochlear place. This information allows one to follow the forward and backward propagation of the traveling wave along the basilar membrane, and to evaluate the otoacoustic response from the time evolution of the stapes displacement. The phase/frequency relation of the response can be predicted, as well as the physical delay associated with the response onset time, to evaluate the relation between different cochlear characteristic times as a function of the stimulus level and of the physical parameters of the model. For a nonlinear cochlea, simplistic frequency-domain interpretations of the otoacoustic response phase behavior may give inconsistent results. Time-domain numerical solutions of the underlying nonlinear and non-local full cochlear model using a large number (thousands) of partitions in space and an adaptive mesh in time are rather time and memory consuming. Therefore, in order to be able to use standard personal computers for simulations reliably, the discretized model has been carefully designed to enforce sparsity of the matrices using a multi-iterative approach. Preliminary results concerning the cochlear characteristic delays are also presented.
Acoustic intensity-based method for sound radiations in a uniform flow
Authors: Yu Chao , Zhou Zhengfang , Zhuang Mei
Published: December 2009

An acoustic intensity-based method (AIBM) is extended and verified for predicting sound radiation in a subsonic uniform flow. The method assumes that the acoustic propagation is governed by the modified Helmholtz equation on and outside of a control surface, which encloses all the noise sources and nonlinear effects. With acoustic pressure derivative and its co-located acoustic pressure as input from an open control surface, the unique solution of the modified Helmholtz equation is obtained by solving the least squares problem. The AIBM is coupled with near-field Computational Fluid Dynamics (CFD)/Computational Aeroacoustics (CAA) methods to predict sound radiation of model aeroacoustic problems. The effectiveness of this hybrid approach has been demonstrated by examples of both tonal and broadband noise. Since the AIBM method is stable and accurate based on the input acoustic data from an open surface in a radiated field, it is therefore advantageous for the far-field prediction of aerodynamics noise propagation when an acoustic input from a closed control surface, like the Ffowcs Williams–Hawkings surface, is not available [Philos. Trans. R. Soc. London, Ser. A 264, 321–342 (1969)].
Shock-induced bubble jetting into a viscous fluid with application to tissue injury in shock-wave lithotripsy
Authors: Freund J. B. , Shukla R. K. , Evan A. P.
Published: December 2009

Shock waves in liquids are known to cause spherical gas bubbles to rapidly collapse and form strong re-entrant jets in the direction of the propagating shock. The interaction of these jets with an adjacent viscous liquid is investigated using finite-volume simulation methods. This configuration serves as a model for tissue injury during shock-wave lithotripsy, a medical procedure to remove kidney stones. In this case, the viscous fluid provides a crude model for the tissue. It is found that for viscosities comparable to what might be expected in tissue, the jet that forms upon collapse of a small bubble fails to penetrate deeply into the viscous fluid “tissue.” A simple model reproduces the penetration distance versus viscosity observed in the simulations and leads to a phenomenological model for the spreading of injury with multiple shocks. For a reasonable selection of a single efficiency parameter, this model is able to reproduce in vivo observations of an apparent 1000-shock threshold before wide-spread tissue injury occurs in targeted kidneys and the approximate extent of this injury after a typical clinical dose of 2000 shock waves.
Extraction of bowing parameters from violin performance combining motion capture and sensors
Authors: Schoonderwaldt E. , Demoucron M.
Published: December 2009

A method is described for measurement of a complete set of bowing parameters in violin performance. Optical motion capture was combined with sensors for accurate measurement of the main bowing parameters (bow position, bow velocity, bow acceleration, bow-bridge distance, and bow force) as well as secondary control parameters (skewness, inclination, and tilt of the bow). In addition, other performance features (moments of on/off in bow-string contact, string played, and bowing direction) were extracted. Detailed descriptions of the calculations of the bowing parameters, features, and calibrations are given. The described system is capable of measuring all bowing parameters without disturbing the player, allowing for detailed studies of musically relevant aspects of bow control and coordination of bowing parameters in bowed-string instrument performance.
The use of non-collinear mixing for nonlinear ultrasonic detection of plasticity and fatigue
Authors: Croxford Anthony J. , Wilcox Paul D. , Drinkwater Bruce W. , Nagy Peter B.
Published: December 2009

This letter reports on the application of the non-collinear mixing technique to the ultrasonic measurement of material nonlinearity to assess plasticity and fatigue damage. Non-collinear mixing is potentially more attractive for assessing material state than other nonlinear ultrasonic techniques because system nonlinearities can be both independently measured and largely eliminated. Here, measurements made on a sample after plastic deformation and on a sample subjected to low-cycle fatigue show that the non-collinear technique is indeed capable of measuring changes in both, and is therefore a viable inspection technique for these types of material degradation.
The pulse tube and the pendulum
Authors: Swift G. W. , Backhaus S.
Published: December 2009

An inverted pulse tube in which gravity-driven convection is suppressed by acoustic oscillations is analogous to an inverted pendulum that is stabilized by high-frequency vibration of its pivot point. Gravity acts on the gas density gradient arising from the end-to-end temperature gradient in the pulse tube, exerting a force proportional to that density gradient, tending to cause convection when the pulse tube is inverted. Meanwhile, a nonlinear effect exerts an opposing force proportional to the square of any part of the density gradient that is not parallel to the oscillation direction. Experiments show that convection is suppressed when the pulse-tube convection number Nptc=ω2a2ΔT/Tavg/[g(αD sin θ−L cos θ)] is greater than 1 in slender tubes, where ω is the radian frequency of the oscillations, a is their amplitude, ΔT is the end-to-end temperature difference, Tavg is the average absolute temperature, g is the acceleration of gravity, L is the length of the pulse tube and D is its diameter, α is about 1.5, and the tip angle θ ranges from 90° for a horizontal tube to 180° for an inverted tube. Theory suggests that the temperature dependence should be ΔT/Tavg instead of ΔT/Tavg.
Comparison of the properties of tonpilz transducers fabricated with ⟨001⟩ fiber-textured lead magnesium niobate-lead titanate ceramic and single crystals
Authors: Brosnan Kristen H. , Messing Gary L. , Markley Douglas C. , Meyer Richard J.
Published: December 2009

Tonpilz transducers are fabricated from ⟨001⟩ fiber-textured 0.72Pb(Mg1/3Nb2/3)O3–0.28PbTiO3 (PMN-28PT) ceramics, obtained by the templated grain growth process, and PMN-28PT ceramic and Bridgman grown single crystals of the same composition. In-water characterization of single element transducers shows higher source levels, higher in-water coupling, and more usable bandwidth for the 81 vol % textured PMN-28PT device than for the ceramic PMN-28PT element. The 81 vol % textured PMN-28PT tonpilz element measured under large signals shows linearity in sound pressure levels up to 0.23 MV/m drive field but undergoes a phase transition due to a lowered transition temperature from the SrTiO3 template particles. Although the textured ceramic performs well in this application, it could be further improved with compositional tailoring to raise the transition temperature and better processing to improve the texture quality. With these improvements textured piezoelectric ceramics will be viable options for medical ultrasound, actuators, and sonar applications because of their ease of processing, compositional homogeneity, and potentially lower cost than single crystal.
Measurement of acoustic streaming in a closed-loop traveling wave resonator using laser Doppler velocimetry
Authors: Desjouy Cyril , Penelet Guillaume , Lotton Pierrick , Blondeau James
Published: December 2009

This paper deals with the measurement of acoustic particle velocity and acoustic streaming velocity in a closed-loop waveguide in which a resonant traveling acoustic wave is sustained by two loudspeakers appropriately controlled in phase and amplitude. An analytical model of the acoustic field and a theoretical estimate of the acoustic streaming are presented. The measurement of acoustic and acoustic streaming velocities is performed using laser Doppler velocimetry. The experimental results obtained show that the curvature of the resonator impacts the acoustic velocity and the profile of acoustic streaming. The quadratic dependence of the acoustic streaming velocity on the acoustic pressure amplitude is verified and the measured cross-sectional average streaming velocity is in good agreement with the value predicted by the theoretical estimate.
Optical tracking of acoustic radiation force impulse-induced dynamics in a tissue-mimicking phantom
Authors: Bouchard Richard R. , Palmeri Mark L. , Pinton Gianmarco F. , Trahey Gregg E. , Streeter Jason E. , Dayton Paul A.
Published: December 2009

Optical tracking was utilized to investigate the acoustic radiation force impulse (ARFI)-induced response, generated by a 5-MHz piston transducer, in a translucent tissue-mimicking phantom. Suspended 10-μm microspheres were tracked axially and laterally at multiple locations throughout the field of view of an optical microscope with 0.5-μm displacement resolution, in both dimensions, and at frame rates of up to 36 kHz. Induced dynamics were successfully captured before, during, and after the ARFI excitation at depths of up to 4.8 mm from the phantom’s proximal boundary. Results are presented for tracked axial and lateral displacements resulting from on-axis and off-axis (i.e., shear wave) acquisitions; these results are compared to matched finite element method modeling and independent ultrasonically based empirical results and yielded reasonable agreement in most cases. A shear wave reflection, generated by the proximal boundary, consistently produced an artifact in tracked displacement data later in time (i.e., after the initial ARFI-induced displacement peak). This tracking method provides high-frame-rate, two-dimensional tracking data and thus could prove useful in the investigation of complex ARFI-induced dynamics in controlled experimental settings.
Engineering modeling of traffic noise in shielded areas in cities
Authors: Salomons Erik M. , Polinder Henk , Lohman Walter J. A. , Zhou Han , Borst Hieronymous C. , Miedema Henk M. E.
Published: December 2009

A computational study of road traffic noise in cities is presented. Based on numerical boundary-element calculations of canyon-to-canyon propagation, an efficient engineering algorithm is developed to calculate the effect of multiple reflections in street canyons. The algorithm is supported by a room-acoustical analysis of the reverberant sound fields in the source and receiver canyons. Using the algorithm, a simple model for traffic noise in cities is developed. Noise maps and exposure distributions of the city of Amsterdam are calculated with the model, and for comparison also with an engineering model that is currently used for traffic noise impact assessments in cities. Considerable differences between the two model predictions are found for shielded buildings with day-evening-night levels of 40–60dB at the facades. Further, an analysis is presented of level differences between the most and the least exposed facades of buildings. Large level differences are found for buildings directly exposed to traffic noise from nearby roads. It is shown that by a redistribution of traffic flow around these buildings, one can achieve low sound levels at quiet sides and a corresponding reduction in the percentage of highly annoyed inhabitants from typically 23% to 18%.
Selective filtering to spurious localization cues in the mammalian auditory brainstem
Authors: Meffin Hamish , Grothe Benedikt
Published: December 2009

The cues used by mammals to localize sound can become corrupted when multiple sound sources are present due to the interference of sound waves. Under such circumstances these localization cues become spurious and often fluctuate rapidly (>100Hz). By contrast, rapid fluctuations in sound pressure level do not indicate a corrupted signal, but rather may convey important information about the sound source. It is proposed that filtering in the auditory brainstem acts to selectively attenuate signals associated with the presence of rapidly fluctuating (spurious) localization cues, but not those associated with slowly varying cues. Further it is proposed that specific inhibitory circuitry in the auditory brainstem, centered on the dorsal nucleus of the lateral lemniscus (DNLL), contributes to this selective filtering. Data from extra-cellular recordings in anesthetized Mongolian gerbils are presented to support these hypotheses for a subpopulation of DNLL neurons. These results provide new insights into how the mammalian auditory system processes information about multiple sound sources.
A simple single-interval adaptive procedure for estimating thresholds in normal and impaired listeners
Authors: Lecluyse Wendy , Meddis Ray
Published: December 2009

This report presents a single-interval adaptive procedure for measuring thresholds in untrained normal and impaired listeners. The accuracy of the procedure is evaluated using Monte Carlo methods and human data allowing a method to be proposed for deciding in advance the number of trials required to achieve a specified level of accuracy. The number of trials depends on the slope of the psychometric function. The slope of the psychometric function is evaluated in normal and impaired listeners, and is found to give a useful guide to the required number of trials. The single-interval up/down procedure is subsequently compared with two other popular traditional methods (two-interval forced-choice, two-down/one-up and maximum-likelihood procedures) and is shown to yield similar thresholds and be more efficient.
Consonant recognition loss in hearing impaired listeners
Authors: Phatak Sandeep A. , Yoon Yang-soo , Gooler David M. , Allen Jont B.
Published: December 2009

This paper presents a compact graphical method for comparing the performance of individual hearing impaired (HI) listeners with that of an average normal hearing (NH) listener on a consonant-by-consonant basis. This representation, named the consonant loss profile (CLP), characterizes the effect of a listener’s hearing loss on each consonant over a range of performance. The CLP shows that the consonant loss, which is the signal-to-noise ratio (SNR) difference at equal NH and HI scores, is consonant-dependent and varies with the score. This variation in the consonant loss reveals that hearing loss renders some consonants unintelligible, while it reduces noise-robustness of some other consonants. The conventional SNR-loss metric ΔSNR50, defined as the SNR difference at 50% recognition score, is insufficient to capture this variation. The ΔSNR50 value is on average 12dB lower when measured with sentences using standard clinical procedures than when measured with nonsense syllables. A listener with symmetric hearing loss may not have identical CLPs for both ears. Some consonant confusions by HI listeners are influenced by the high-frequency hearing loss even at a presentation level as high as 85dB sound pressure level.