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Jun 2012

Volume 131, Issue 6, pp. EL421-4870

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Vowel enhancement effects in cochlear-implant users

Ningyuan Wang, Heather Kreft, and Andrew J. Oxenham

J. Acoust. Soc. Am. Volume 131, Issue 6, pp. EL421-EL426 (2012); (6 pages) | Cited 3 times

Online Publication Date: 04 May 2012

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Auditory enhancement of certain frequencies can occur through prior stimulation of surrounding frequency regions. The underlying neural mechanisms are unknown, but may involve stimulus-driven changes in cochlear gain via the medial olivocochlear complex (MOC) efferents. Cochlear implants (CIs) bypass the cochlea and stimulate the auditory nerve directly. If the MOC plays a critical role in enhancement then CI users should not exhibit this effect. Results using vowel stimuli, with and without preceding sounds designed to enhance formants, provided evidence of auditory enhancement in both normal-hearing listeners and CI users, suggesting that vowel enhancement is not mediated solely by cochlear effects.
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43.64.Me Effects of electrical stimulation, cochlear implant
43.66.Ba Models and theories of auditory processes
43.71.Es Vowel and consonant perception; perception of words, sentences, and fluent speech
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Categorical perception of intonation contrasts: Effects of listeners’ language background

Chang Liu and Amanda Rodriguez

J. Acoust. Soc. Am. Volume 131, Issue 6, pp. EL427-EL433 (2012); (7 pages)

Online Publication Date: 04 May 2012

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Intonation perception of English speech was examined for English- and Chinese-native listeners. F0 contour was manipulated from falling to rising patterns for the final words of three sentences. Listener’s task was to identify and discriminate the intonation of each sentence (question versus statement). English and Chinese listeners had significant differences in the identification functions such as the categorical boundary and the slope. In the discrimination functions, Chinese listeners showed greater peakedness than English peers. The cross-linguistic differences in intonation perception were similar to the previous findings in perception of lexical tones, likely due to listeners’ language background differences.
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43.71.Hw Cross-language perception of speech
43.71.Sy Spoken language processing by humans
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Sound propagation in saturated gas-vapor-droplet suspensions with droplet evaporation and nonlinear relaxation

Max Kandula

J. Acoust. Soc. Am. Volume 131, Issue 6, pp. EL434-EL440 (2012); (7 pages)

Online Publication Date: 04 May 2012

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The Sound attenuation and dispersion in saturated gas-vapor-droplet mixture in the presence of evaporation has been investigated theoretically. The theory is based on an extension of the work of Davidson [J. Atmos. Sci. 32(11), 2201–2205 (1975)] to accommodate the effects of nonlinear particle relaxation processes of mass, momentum and energy transfer on sound attenuation and dispersion. The results indicate the existence of a spectral broadening effect in the attenuation coefficient (scaled with respect to the peak value) with a decrease in droplet mass concentration. It is further shown that for large values of the droplet concentration the scaled attenuation coefficient is characterized by a universal spectrum independent of droplet mass concentration.
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43.20.Hq Velocity and attenuation of acoustic waves
43.25.Ed Effect of nonlinearity on velocity and attenuation
43.50.Nm Aerodynamic and jet noise
43.50.Gf Noise control at source: redesign, application of absorptive materials and reactive elements, mufflers, noise silencers, noise barriers, and attenuators, etc.
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Field transformational approach to three-dimensional scattering from two-dimensional rough surfaces

Kevin B. Smith

J. Acoust. Soc. Am. Volume 131, Issue 6, pp. EL441-EL447 (2012); (7 pages) | Cited 1 time

Online Publication Date: 04 May 2012

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In 1985, Tappert and Nghiem-Phu introduced a field-transformation technique for computing rough surface scattering from a parabolic equation model utilizing a split-step Fourier marching algorithm. The approach was based on a two-dimensional parabolic equation with a standard operator approximation that was capable of computing scattering from a one-dimensional rough surface. Although this approach has been used extensively and effectively, extensions of this approach to higher order approximations or three-dimensional propagation have only recently been investigated. In this work, the expressions that incorporate higher-order approximations and three-dimensional scattering from two-dimensional rough surfaces are presented. The implications of some computationally necessary approximations are also provided.
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43.30.Hw Rough interface scattering
43.20.Fn Scattering of acoustic waves
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Echolocation behavior of franciscana dolphins (Pontoporia blainvillei) in the wild

Mariana L. Melcón, , Mauricio Failla, , and Miguel A. Iñíguez

J. Acoust. Soc. Am. Volume 131, Issue 6, pp. EL448-EL453 (2012); (6 pages)

Online Publication Date: 08 May 2012

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Franciscana dolphins are small odontocetes hard to study in the field. In particular, little is known on their echolocation behavior in the wild. In this study we recorded 357 min and analyzed 1019 echolocation signals in the Rio Negro Estuary, Argentina. The clicks had a peak frequency at 139 kHz, and a bandwidth of 19 kHz, ranging from 130 to 149 kHz. This is the first study describing echolocation signals of franciscana dolphins in the wild, showing the presence of narrow-band high frequency signals in these dolphins. Whether they use other vocalizations to communicate or not remains uncertain.
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43.80.Ka Sound production by animals: mechanisms, characteristics, populations, biosonar
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About the transition frequency in Biot’s theory

Patrick S. Kurzeja and Holger Steeb

J. Acoust. Soc. Am. Volume 131, Issue 6, pp. EL454-EL460 (2012); (7 pages) | Cited 1 time

Online Publication Date: 09 May 2012

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Biot’s theory of wave propagation in porous media includes a characteristic frequency which is used to distinguish the low-frequency from the high-frequency range. Its determination is based on an investigation of fluid flow through different pore geometries on a smaller scale and a subsequent upscaling process. This idea is limited due to the assumptions made on the smaller scale. It can be enhanced for a general two-phase system by three properties: Inertia of the solid, elasticity of the solid, and frequency dependent corrections of the momentum exchange. They become important for highly porous media with liquids.
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43.20.Bi Mathematical theory of wave propagation
43.20.Jr Velocity and attenuation of elastic and poroelastic waves
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“Ladder” structure in tonal noise generated by laminar flow around an airfoil

Tze Pei Chong and Phillip Joseph

J. Acoust. Soc. Am. Volume 131, Issue 6, pp. EL461-EL467 (2012); (7 pages)

Online Publication Date: 14 May 2012

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The presence of a “ladder” structure in the airfoil tonal noise was discovered in the 1970s, but its mechanism hitherto remains a subject of continual investigation in the research community. Based on the measured noise results and some numerical analysis presented in this letter, the variations of four types of airfoil tonal noise frequencies with the flow velocity were analyzed individually. The ladder structure is proposed to be caused by the acoustic/hydrodynamic frequency lag between the scattering of the boundary layer instability noise and the discrete noise produced by an aeroacoustic feedback loop.
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43.28.Ra Generation of sound by fluid flow, aerodynamic sound and turbulence
43.28.Bj Mechanisms affecting sound propagation in air, sound speed in the air
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Discriminating resonant targets from clutter using Lanczos iterated single-channel time reversal

Zachary J. Waters and Paul E. Barbone

J. Acoust. Soc. Am. Volume 131, Issue 6, pp. EL468-EL474 (2012); (7 pages)

Online Publication Date: 16 May 2012

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Power iterated single-channel time-reversal is extended to employ Lanczos iterations. The properties of these algorithms are studied in the presence of varying levels of noise and broadband clutter. It is shown the Lanczos iterated method possesses superior convergence properties in comparison to the standard power iterated technique. Results demonstrate that such algorithms provide an efficient means through which to isolate and extract the properties of resonant scatterers in the presence of noise and coherent interference.
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43.60.Tj Wave front reconstruction, acoustic time-reversal, and phase conjugation
43.30.Zk Experimental modeling
43.20.Fn Scattering of acoustic waves
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Exploiting pattern transformation to tune phononic band gaps in a two-dimensional granular crystal

F. Göncü, S. Luding, and K. Bertoldi

J. Acoust. Soc. Am. Volume 131, Issue 6, pp. EL475-EL480 (2012); (6 pages)

Online Publication Date: 17 May 2012

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The band structure of a two-dimensional granular crystal composed of silicone rubber and polytetrafluoroethylene (PTFE) cylinders is investigated numerically. This system was previously shown to undergo a pattern transformation with uniaxial compression by Göncü et al. [Soft Matter 7, 2321 (2011)]. The dispersion relations of the crystal are computed at different levels of deformation to demonstrate the tunability of the band structure, which is strongly affected by the pattern transformation that induces new band gaps. Replacement of PTFE particles with rubber ones reveals that the change of the band structure is essentially governed by pattern transformation rather than particles’ mechanical properties.
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43.20.El Reflection, refraction, diffraction of acoustic waves
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A parametric study of error in the parabolic approximation of focused axisymmetric ultrasound beams

Joshua E. Soneson

J. Acoust. Soc. Am. Volume 131, Issue 6, pp. EL481-EL486 (2012); (6 pages)

Online Publication Date: 24 May 2012

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The parabolic approximation results in a tractible model for studying ultrasound beams, but the limits of validity of the approximation are often presented only qualitatively. In this work the most common model for axisymmetric ultrasound beam propagation, the Kuznetsov–Zabolotskaya–Khokhlov equation, is directly compared with the more general Westervelt equation with regard to diffractive and absorptive effects in continuous wave beams. The parametric study compares the solutions of the two models as a function of source frequency and focusing geometry using peak focal pressure, the axial location at which that peak occurs, and the loss due to absorption as metrics.
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43.80.Sh Medical use of ultrasonics for tissue modification (permanent and temporary)
43.35.Bf Ultrasonic velocity, dispersion, scattering, diffraction, and attenuation in liquids, liquid crystals, suspensions, and emulsions
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Modified locus equations categorize stop place in a perceptually realistic time frame

Ariane E. Rhone and Allard Jongman

J. Acoust. Soc. Am. Volume 131, Issue 6, pp. EL487-EL491 (2012); (5 pages)

Online Publication Date: 25 May 2012

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Slope and y-intercepts of locus equations have previously been shown to successfully classify place of articulation for English voiced stop consonants when derived from measurements at vowel onset and vowel midpoint. However, listeners are capable of identifying English voiced stops when less than 30 ms of vowel is presented. The present results show that modified locus equation measurements made within the first several pitch periods of a vowel following an English voiced stop were also successful at classifying place of articulation, consistent with the amount of vocalic information necessary for perceptual identification of English voiced stops /b d g/.
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43.70.Fq Acoustical correlates of phonetic segments and suprasegmental properties: stress, timing, and intonation
43.70.Mn Relations between speech production and perception
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Piecewise coherent mode processing of acoustic data recorded on two horizontally separated vertical line arrays

Ilya A. Udovydchenkov, Michael G. Brown, and Timothy F. Duda

J. Acoust. Soc. Am. Volume 131, Issue 6, pp. EL492-EL498 (2012); (7 pages)

Online Publication Date: 25 May 2012

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Abstract: Motivated by measurements made in the 2004 Long-Range Ocean Acoustic Propagation Experiment (LOAPEX), the problem of mode processing transient acoustic signals collected on two nearby vertical line arrays is considered. The first three moments (centroid, variance, and skewness) of broadband distributions of acoustic energy with fixed mode number (referred to as modal group arrivals) are estimated. It is shown that despite the absence of signal coherence between the two arrays and poor high mode number energy resolution, the centroid and variance of these distributions can be estimated with tolerable errors using piecewise coherent mode processing as described in this paper.
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43.30.Bp Normal mode propagation of sound in water
43.60.Ac Theory of acoustic signal processing
43.60.Fg Acoustic array systems and processing, beam-forming
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Temporal offset judgments for concurrent vowels by young, middle-aged, and older adults

Daniel Fogerty, Diane Kewley-Port, and Larry E. Humes

J. Acoust. Soc. Am. Volume 131, Issue 6, pp. EL499-EL505 (2012); (7 pages)

Online Publication Date: 25 May 2012

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Temporal processing declines with age may reduce the processing of concurrent vowels. For this study, listeners categorized vowel pairs varying in temporal asynchrony as one sound, two overlapping sounds, or two sounds separated by a gap. Two boundaries separating the three response categories, multiplicity and gap-identification, were measured. Compared to young and middle-aged listeners, older listeners required longer temporal offsets for multiplicity. Middle-aged and older listeners also required longer offsets for gap-identification. For older listeners, correlations with various temporal processing tasks indicated that vowel temporal-order thresholds were related to multiplicity, while age and non-speech gap-detection thresholds were related to gap-identification.
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43.71.Rt Sensory mechanisms in speech perception
43.71.Es Vowel and consonant perception; perception of words, sentences, and fluent speech
43.66.Sr Deafness, audiometry, aging effects
43.71.An Models and theories of speech perception
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Resonance frequencies of a spherical aluminum shell subject to static internal pressure

Andrew A. Piacsek, Sami Abdul-Wahid, and Robert Taylor

J. Acoust. Soc. Am. Volume 131, Issue 6, pp. EL506-EL512 (2012); (7 pages)

Online Publication Date: 29 May 2012

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Measurements of the vibrational response of a spherical aluminum shell subject to changes in the interior pressure clearly demonstrate that resonance frequencies shift higher as the pressure is increased. The frequency shift appears to be smaller for longitudinal modes than for bending wave modes. The magnitude of frequency shift is comparable to analytical predictions made for thin cylindrical shells. Changes in the amplitudes of resonance peaks are also observed. A possible application of this result is a method for noninvasively monitoring pressure changes inside sealed containers, including intracranial pressure in humans.
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43.40.Ey Vibrations of shells
43.25.Gf Standing waves; resonance
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