bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigating the role of specific facial information in audio-visual speech perception
Authors: Smeele P. M. T. , Hahnlen Lisa D. , Stevens Erica B. , Kuhl Patricia K. , Meltzoff Andrew N.
Published: October 2005

When hearing and seeing a person speak, people receive both auditory and visual speech information. The contribution made by visual speech information has been demonstrated in a wide variety of conditions, most clearly when conflicting auditory and visual information is presented. In this study an investigation was performed to determine which aspects of the face most strongly influence audio-visual speech perception. The visual stimulus was manipulated using special effects techniques to isolate three specific ‘‘articulatory parts:’’ lips only, oral cavity only, or jaw only. These ‘‘parts’’ and their combinations were dubbed with auditory tokens to create ‘‘fusion’’ stimuli (A/aba/ + V/aga/) and ‘‘combination’’ stimuli (A/aga/ + V/aba/). Results indicated that visual information from jaw-only movements was not sufficient to induce illusory effects. However, for the combination condition, seeing moving lips or the inside of the speaker’s mouth produced substantial audio-visual effects. Additional visual information from other articulators did not significantly increase the effect. In the fusion situation, both the lips and oral cavity were necessary to obtain illusory responses, whereas individually they produced very few. The results suggest that visual information from the lips and oral cavity together are sufficient to influence auditory speech processing. [Research supported by NICHD.]
Stress identification by hearing-impaired listeners
Authors: Barac-Cikoja Dragana , Revoile Sally
Published: October 2005

Some acoustic correlates of stress perception were studied for listeners with moderate to profound hearing loss. The sentence ‘‘You put VCV to bed’’ was spoken with emphasis on each of the main constituents (you, put, VCV, to bed) respectively, yielding four stress contexts. For each stress context, ten different sentence utterances were tested. The sentences were modified acoustically to neutralize the temporal and/or amplitude prominence of the stressed word. Hearing-impaired (n=22) and normal-hearing listeners (n=8) identified the stressed word for the modified and unmodified sentences. Contrary to the performance in normal-hearing listeners, stress perception by the hearing-impaired listeners was significantly reduced when both amplitude and temporal characteristics of the stressed word were modified. Less of an effect occurred when only amplitude or temporal characteristics alone were neutralized. Results are discussed with reference to the extent and rate of F0 change across the sentence for the four stress contexts, and the accessibility of the intonational cues to the hearing impaired subjects as predicted by several audiological and psychoacoustic variables. [Work supported by NIH.]
Effects of formant bandwidth on the performance of two cochlear implant processing strategies
Authors: Hawks John W. , Fourakis Marios S. , Skinner Margaret W. , Holden Timothy A. , Holden L. K.
Published: October 2005

The aim of the experiment reported here was to examine the responses to synthetic vowels of the processor of the Nucleus Cochlear Implant System, using the MPEAK and SPEAK speech coding strategies. In previous work with natural vowels (Skinner etal., submitted to Ear Hear.), it was found that second formant information was better transmitted using the SPEAK strategy, while first formant information was better transmitted using the MPEAK strategy. Examination of the output of the SPEAK processor showed activation of multiple adjacent electrodes resulting in less distinct spectral cues than with MPEAK. This prompted the present investigation, which uses synthetic vowels with varying formant bandwidths. Four synthetic vowels, which had been identified consistently by normal hearing subjects as one of [I, ε, U, inverted vee] were used as anchor points for the creation of continua in which the bandwidths of the first and second formants were systematically and independently decreased in steps of 10% to a minimum of 50% of the formant bandwidths of the anchor stimuli. Results from the processors and identifications from subjects using the two processing stategies will be presented and compared. [Work supported by NIH.]
Creating and confirming acoustic targets in compression amplification
Authors: Yanz Jerry L. , Delage David J.
Published: October 2005

The recent increase in the use of compression amplifiers in hearing aids has created the need for more sophisticated fitting algorithms to help select the hearing aid characteristics—gain, output, compression threshold and compression ratio—most appropriate for individual hearing losses. Conventional prescriptive formulas (NAL-R, POGO, etc.), intended for linear amplifiers, are not adequate. The Independent Hearing Aid Fitting Forum (IHAFF) recently published a protocol for defining these variables using multiple existing clinical instruments, computer software, and normative corrections. In this presentation the Prophet Hearing Aid Fitting System will be described. Prophet was developed to accomplish the goals of the IHAFF protocol, as well as the FIG6 approach of Killion, in a single integrated, PC-based instrument. The system sharpens the accuracy of amplification targets by calibrating all signals in dB SPL with real ear values where appropriate, thereby eliminating any reliance on inherently variable HL norms. In addition to creating acoustic targets, it confirms the fit to target by measuring the response of the hearing aid to a multi-level, speech-noise stimulus.
Esophageal speech analysis
Authors: Pastiadis Costas , Politis Zafiris G. , Papanikolaou George
Published: October 2005

Aspects of esophageal speech are investigated in this paper. Esophageal speech is produced by laryngectomized people who utter by expelling air constricted under the entrance of the esophagus, forcing the cricopharyngeal muscle to oscillate equivalently to vocal cords in normal speakers. Nine male esophageal speakers were used for the analysis. Spoken material consisted of Greek vowels and syllables (CV, CCV, VC), each repeated three times continuously by each speaker. F0 values and plots were obtained for all speakers using central clipping autocorrelation, cepstrum analysis, and a modified Hilbert transform envelope method that seemed to give more consistent results among others. Most frequently observed F0 values varied from speaker to speaker with an average of 73 Hz. F1 vs F2 plots for Greek phonemes α, ε, ι, o, oυ, were obtained by LPC. Deviations from normal speakers were very small. Significant similarity to English equivalent phonemes was also observed. Speech power versus time slope for vowel-type utterances was investigated as a measure of power reduction rate, showing an average of −86 dB/s. Finally, implications about source volume velocity are made using LPC inverse filtering. Cepstrum analysis revealed a −6-dB/oct voice source spectral tilt instead of −12 dB/oct for normal speakers.
Analytical study of pathologic tremulous voices of Japanese-speaking patients
Authors: Kosaki Hiroko , Kaga Kimitaka , Niimi Seiji , Kumada Masanobu , Hirose Hajime
Published: October 2005

This study was undertaken to clarify the major characteristics of voices of the Japanese-speaking patients of the adductor spasmodic dysphonia. The mechanism of the tremulous voice was also studied. For Japanese-speaking patients, to make a proper diagnosis of adductor spasmodic dysphonia, an evaluation method of the grade of the disease is needed. Sound spectrographic analysis was applied. First, the voices of the adductor spasmodic dysphonia patients were compared with the voices of other tremulous voice disease patients. Second, the voices of the different stages of adductor spasmodic dysphonia were analyzed. In the first study, results revealed that adductor spasmodic dysphonia voices showed irregularity of the fluctuation frequency in both pitch and intensity, while the voices with essential voice tremor showed a periodic fluctuation in pitch and intensity. In the second study, it was indicated that the cessation and fine flutter of the voice have a major role in the grade of the disease. With those results, phonological measurement and clinical feature can be matched. By evaluation of the irregularity of the voice, the diagnosis of tremulous voices might be confirmed. It was suggested that contributing factors to the voice symptom were not uniform.
Closed-set response formats: An evaluation within the framework of the neighborhood activation model
Authors: Prohofsky Rebecca S. , Sommers Mitchell S.
Published: October 2005

It has been suggested that open- and closed-set response formats engage distinct perceptual mechanisms during spoken word recognition. One finding consistent with this hypothesis is that lexical difficulty (neighborhood density and neighborhood frequency) reduce identification performance in open- but not closed-set formats [Kirk etal., Ann. Otol. Rhinol. Laryngol. (in press)]. An alternative explanation for the differential effects of response format on lexical difficulty in this earlier study, however, is that the response alternatives were not systematically selected to maximize confusability with the target items. Therefore, the present investigation compared the effects of lexical difficulty in open- and closed-set response formats when the response alternatives in the closed-set condition were the five words most confusable with the target item. Preliminary results indicate that, relative to the open-set condition, when the difficulty of alternatives is controlled, identification within the closed-set format is improved for hard, but not for easy, words. It is hypothesized that the improved word recognition for hard words in closed-set formats is the result of reducing the viable candidate set. In contrast, the already small candidate set of easy words minimizes the benefits of reducing the number of viable candidate items.
Effects of compound priming on listeners’ identification of a /kVC/ continuum
Authors: Nearey Terrance M. , Kiefte Michael , Guilbault Christian , Kabata Kaori , Xia Zhang
Published: October 2005

A continuum was synthesized to span the words cop, cup, cob, and cub. Two cues were varied in six steps each. Vowel F2 ranged from 960 to 1160 Hz. Voice bar duration for the final consonant ranged from 10 to 60 ms. Other properties approximated the average the four words pronounced by a male speaker in the compound nouns: trafficcop, teacup, corncob, and bearcub. The four context words, traffic, tea, corn, and bear, were also synthesized. Thirteen listeners categorized ten replications of the stimuli in each of five contexts: as isolated words and following each of the context words. As expected, words are favored in appropriate contexts. Logistic regression indicates that about 96% of variance in listeners’ responses can be attributed to phoneme-level stimulus effects and to stimulus-independent (phonological and lexical) biases. There is also evidence for small changes in sensitivity to cues as a function of lexical context. The latter result is of interest for certain alternative models [D. Massaro, Cog. Psych. 23, 558–564 (1991)]. However, observed changes in sensitivity do not relate well to predictions from any existing theory. [Work supported by SSHRC.]
Scattering strength cannot depend on the length of a pulse
Authors: Henyey Frank S. , Thorsos Eric I. , Nathwani K. Miguel
Published: October 2005

Reilly etal. [J. Acoust. Soc. Am. 97, 3385–3386 (A) (1995)] presented experimental results for low-frequency bottom scattering strength which appear to show pulse length dependence. It is shown that the scattering strength is independent of pulse length under the assumptions of (1) linear acoustics, and either (2a) the scatterers are not moving, as for ocean bottom scattering, or (2b) the statistics of the scatterers are time independent (a stationary process) and uncorrelated to pulse timing, as for ocean surface zone scattering. These results hold if the pulses have the same frequency spectrum. In the usual case that their spectra are slightly different, rapid frequency dependence can appear to give pulse length dependence. In case (2a), the ensemble average removes that part of rapid frequency dependence due to random interference between returns from different scatterers or different parts of the same scatterer that appear in a single return. Rapid variation of the average received power can bias the measured scattering strength for longer pulses, but this effect can be removed from the data. Statistics other than scattering strength, such as peak return, are generally pulse length dependent.
Modal analysis and materials considerations in Caribbean steelpans
Authors: Hansen Uwe , Rohner Felix , Rossing Thomas D.
Published: October 2005

Modal analysis contributes significantly to an understanding of the vibrational patterns and the rich spectral tone color of the Caribbean steelpan sound. This will be illustrated with several examples of computer animations of steelpan normal modes. In addition to showing some of the low-order modes which contribute strongly to the radiated sound, these animations also show direct linear coupling effects between note sections. Since impact excitation modal analysis is fundamentally a linear experimental technique a solenoid driven excitation hammer minimizes amplitude-dependent nonlinearities. PANART artisans have emphasized tonal consistency through material and processing controls. This includes steel production to pan crafters specifications, custom drum manufacture, and a systematic sandwich surface hardening process. A European cultural influence has led to some departure from traditional Caribbean standards. Examples of note spectra and modal analysis computer animations will be shown.
A numerical approach of the transmission of a polyurethane foam sphere in an impulse regime
Authors: Sfaoui Abdelkader
Published: October 2005

Among the phenomena envolved in the propagation of an acoustic wave in a diphasic medium such as a polyurethane foam, there is the air/structure interaction. According to the Biot theory the latter is characterized by two parameters: ρa the inertial coupling and b the resistivity of the fluid flow. When the material porosity, the Young’s modulus, and the Poisson’s ratio are determined [G. Deprez, J. Phys. Suppl. C2, 43–52 (1990) and A. Sfaoui, J. Acoust. Soc. Am. 97, 1046–1052 (1995)], it is sufficient to adjust these parameters to describe the acoustic propagation. In this aim, an experimental technique has been elaborated. It consists in studying the transmission of a broadband impulse by a foam sphere. The transmission coefficient is obtained after time filtering and fast Fourier transform calculation of two signals: the incident signal and the transmitted signal at the center of the sphere. By selecting the curve to fit the Young’s modulus data [A. Sfaoui, J. Acoust. Soc. Am. 97, 1046–1052 (1995)] by means of a regression program, the transmission coefficient is numerically analyzed in the range of 0–20 kHz. It follows that the transmitted signal is the superimposition of the Biot fast and slow waves.
The effect of edge constraints on the surface normal impedance of a layer of elastic porous material
Authors: Bolton J.Stuart , Desmet Wim , Shiau Nae-Ming
Published: October 2005

Previous work has indicated that the acoustical behavior of partially reticulated noise control foams can be sensitive to small mounting details. It is thus reasonable to expect that the surface normal impedance of a foam sample placed in a standing wave tube will depend on the degree to which the sample is constrained at its edges. Here a two-dimensional version of the Biot theory governing wave propagation in elastic porous materials has been used to investigate the effect of such an edge constraint. First, the allowed modes of propagation within a constrained foam layer were identified. Those modes were then used to predict the response of the constrained layer to an incident plane wave. A comparison of that prediction with the surface normal impedance of an unconstrained half-space of the same material has shown that the principal effect of the edge constraints is to stiffen the sample at frequencies below the cut on of the first shearing mode within the constrained layer. A simple criterion based on the shear stiffness of the elastic porous material has been developed to give the frequency below which the edge-stiffening effect may have a significant effect on a sample’s surface normal impedance.
Finite element models for sound transmission through foam wedges and foam layers having spatially graded properties
Authors: Kang Yeoni June , Bolton J. Stuart
Published: October 2005

Recently a finite element implementation of the Biot elastic porous material theory has been developed for the purpose of modeling and optimizing partially reticulated foam noise control treatments [Y. J. Kang and J. S. Bolton, J. Acoust. Soc. Am. 98, 635–643 (1995)]. In the present work, that finite element formulation was used first to study normal incidence sound transmission through a foam wedge contained in a hard-walled duct. It has been found that the transmission loss of the wedge is significantly higher than that of a plane foam layer of the same volume in some frequency bands. The increase in transmission loss was found to result from the conversion within the foam of the incident plane wave into a higher-order symmetric mode that does not radiate efficiently from the rear surface of the foam wedge. It has also been found that the same increase in transmission loss can be produced using a plane, constant depth foam layer if the tortuosity is varied across the width (not the depth) of the foam layer. Thus it will be shown that spatially graded lining materials may be used to enhance the transmission loss of double panel systems.
An efficient solution method for solving poroelasticity dynamic problems using the finite-element method
Authors: Panneton Raymond , Atalla Noureddine
Published: October 2005

Recently, a three-dimensional (3-D) finite-element formulation for the dynamic behavior of poroelastic materials was developed [Panneton etal., J. Acoust. Soc. Am. 96, 3339(A) (1994)]. The fluid and solid macroscopic displacements were used as the fundamental variables. The formulation was based on an analogy with 3-D elastic solid elements. However, six degrees-of-freedom (dof) per node were necessary. For large-scale finite-element models and multifrequency analyses, the use of 6 dof per node has proven to be time- and memory-consuming. Indeed, the complex dissipation mechanisms and frequency-dependent poroelastic coefficients prevent the use of efficient classical solution methods, such as mode superposition method. To alleviate the problem, an efficient solution method is presented. This method is based on assumptions about the poroelastic stress-strain relations and their frequency dependence. A parametric study on the dynamic behavior of poroelastic materials will be presented to back up the used assumptions. Finally, results will be shown to prove that the proposed method leads to substantial gain in computer time without loss of accuracy.
Acoustic wave processes in viscoelastic porous media
Authors: Margulies Timothy S.
Published: October 2005

An understanding of acoustic waves in deformable, porous media has important applications in understanding propagation characteristics through ocean sediments, as well as, in the seismicity of rocks and earthquake design. Continuum balance equations for viscoelastic mixtures are applied to wave dynamics of fluid flow in porous media. Stress representations for the response of the solid phase, for example, Kelvin-Voigt are assumed and compared to frame-indifferent fractional calculus stress tensor assumptions. The linear plane-wave dynamics are developed for homogeneous materials and inhomogeneous layered porous media using matrix propagator techniques. Several specific examples and concluding remarks on possible future directions for theoretical and experimental investigations will be given to gain a better understanding of the effects of coupled deformable solid and fluid motions, in addition to relaxation effects such as chemical reactions or multiphase mass-transfer processes.
Effect of trapped gas on acoustic properties of model sediments
Authors: Wang Mark , Shields F. Douglas , Sabatier James M. , Lafleur L. Dwynn
Published: October 2005

Sound speeds and attenuations have been measured in sediments contained in a steel tube 2.5 in. i.d., 3.5 in. o.d., and 5.5 ft long. Measurements have been made in two kinds of sand and three sizes of glass beads over a frequency range of 2–20 kHz. In order to study the effect of trapped gases on the acoustical properties of the sediment, a dry sediment was evacuated and then flooded with degassed water. The results are highly sensitive to the packing of the sediment, and are slightly influenced by the pumping process. The measured sound speeds and absorptions after correction for the effects of the yielding wall are compared with those expected from the Biot theory. [Work supported by ONR.]
Axisymmetric free vibrations of finite poroelastic bone
Authors: Natarajan K. , Paul H. S.
Published: October 2005

Axisymmetric free vibrations of poroelastic finite cylindrical bone, which behaves as transversely isotropic material, are investigated. Both curved and plane end surfaces of the solid cylinder are free from mechanical stresses and average fluid stresses. Two sets of basic solutions are derived to the equations of motion and poroelastic equation (due to Biot’s theory) by applying variable separable technique. From the shear stress-free boundary conditions, eigenvalues for wave numbers are found. Using the basic solutions and eigen wave numbers, solutions to the mechanical displacements and the fluid velocities are developed in series form. The series form solutions satisfy the shear stress-free boundary conditions exactly term by term. Remaining boundary conditions are satisfied by an orthogonalization procedure using trigonometric functions and first kind Bessel functions. Natural frequencies of vibrations are calculated for human bone by varying the number of terms in the series that are tabulated. The series solutions converge rapidly within few terms. For various half-length to radius ratios of the finite cylinder, natural frequencies are computed and presented graphically. [One of the authors (K.N.) acknowledges CSIR, New Delhi, India for the financial support.]
Acoustic wave propagation through actin/alpha-actinin gels
Authors: Margulies Timothy S.
Published: October 2005

The acoustic properties of mixtures of actin filaments and alpha-actinin depend in a complicated way on both the concentration and affinity of the cross-linking protein for actin. The dependence of sound absorption and speed through actin filaments at low frequencies has been analyzed for one-dimensional waves in a viscoelastic medium. Estimates are made using rheology data for the complex modulus versus deformation rate for actin filaments including the effects of various amounts of concentration of alpha-actinin. Calculations of acoustic waves show the influence of the transition from an isotropic viscoelastic solid to a viscous fluid of actin bundles. The perturbative approach for nonlinear wave propagation in viscoelastic media was also applied to investigate gel properties and influences on waveform modification.
Edge wave on-axis behind a disk or aperture having a random edge
Authors: Menounou Pinelopi , Bailey Michael R. , Blackstock David T.
Published: October 2005

The Helmholtz–Kirchhoff intergral is used to predict the edge wave on-axis behind a disk (or an aperture) that has a ragged edge. The ragged edge is modeled as being made up of N arcs of equal angle (subtended from the center of the disk) but differing radii ri. The on-axis edge wave is thus a sum of N scattered signals, each of which has a common amplitude proportional to 1/N but a different delay time τi=√r2i+s2/c0, where s is the axial distance from the disk. A formula has been derived for the edge wave’s rms pressure, in terms of N and the incident wave’s rms pressure and autocorrelation function. The formula has been evaluated for incident waves that are sinusoidal, random (noise), and transient. The calculations agree reasonably well with underwater measurements [J. Acoust. Soc. Am. 92, 2359(A) (1992)] made with a spark source and various apertures and disks (biradial, triradial, and ragged). When N is large and the range of values of τi is large enough, the rms value of the edge wave approaches zero. [Work supported by ONR, NASA, and the ARL:UT IR&D program.]
Analysis of the diffraction process near a corner of a rigid wedge
Authors: Ueda Mitsuhiro
Published: October 2005

In order to analyze the sound field near a corner of a rigid wedge, the virtual discontinuity principle of diffraction (VDPD) that has been proposed and the representation of the sound field that satisfies both the wave equation and boundary conditions that can be constituted by this principle [J. Acoust. Soc. Am. 95, 2354–2362 (1994)] is applied to this problem. Then the sound pressure on the rigid surface can be expressed as an integral of the particle velocity normal to an extension line of one of the wedge surfaces where a point of interest is located on it. On the other hand, the particle velocity at any field point can be expressed as an integral of the sound pressure along the rigid surface using the Green’s theorem. Thus there are two relations between the sound pressure on the rigid surface and the particle velocity normal to the extension lines of the wedge. Analyzing these two relations near the corner of the wedge, the diffraction process that occurs near the corner becomes clear. Its good understanding will surely help in understanding the nature of waves diffracted by a polygon.
Acoustic radiation force on a rigid sphere in a viscous heat-conducting fluid
Authors: Doinikov Alexander A.
Published: October 2005

This study generalizes earlier calculations by the author [A. A. Doinikov, Proc. R. Soc. London Ser. A 447, 447–466 (1994); A. A. Doinikov, J. Acoust. Soc. Am. 96, 3100–3105 (1994)] to cases where heat conduction of the host fluid and the sphere material is no longer negligible. Three types of an incident sound field were considered: a plane traveling wave, a plane standing wave, and a diverging spherical wave. Effects of heat conduction on the radiation force were found to be greatest for traveling and spherical waves and for spheres less dense than the host fluid. In particular, it is found that traveling waves can urge these spheres away both from and toward the sound transducer and diverging (not standing) spherical waves can cause them to levitate. These results are unusual from the standpoint of the theory of acoustic radiation forces for perfect fluids. [Work supported by the Ministry of Education and Science of the Republic of Belarus.]
Transfer coupler reciprocity method for the absolute low-frequency calibration of field hydrophones under full environmental conditions
Authors: Zalesak Joseph F.
Published: October 2005

The reciprocity coupler is a closed chamber used for the absolute calibration of standard hydrophones at low frequencies. There is a need to extend this capability to field hydrophones that are not specifically designed for use in a reciprocity coupler. This requires that one determine the reciprocity parameter for the coupler with the field hydrophone installed. Uncertainties in the effective volume and compliance of the coupler with the field hydrophone installed preclude calculation of the reciprocity parameter from first principles. The transfer reciprocity method described here provides a way to measure the reciprocity parameter of an ill-characterized coupler by first making measurements in a well-characterized coupler without the field hydrophone. An error analysis is presented indicating the current state of the existing reciprocity coupler including the transfer reciprocity method. The analysis shows that there is a systematic error that can be eliminated by correcting the sensitivities obtained using the transfer reciprocity method. This error has a frequency-independent component of 0.31 dB and a frequency-dependent component ranging from 0.1 dB at 700 Hz to 1.0 dB at 2000 Hz. After correcting for the systematic error, the uncertainty in the sensitivity is ±0.25 dB for frequencies below 1000 Hz, rising to ±0.35 dB for frequencies near 2000 Hz.
Experimental investigation of onset threshold for shape oscillations for air bubbles in 1g
Authors: Gaitan D. Felipe , Holt R. Glynn
Published: October 2005

Experimental observations of single bubble oscillations have yielded a wide variety of phenomena: periodic and period-doubled spherical oscillations; periodic, quasiperiodic and chaotic multimode shape oscillations; and, most recently, periodic, period-doubled, quasiperiodic, and chaotic sonoluminescence. In an effort to determine the effect of gravity on these phenomena, the acoustic pressure threshold for shape oscillations of single gas bubbles in a 1g environment was measured. The bubble sizes varied between 20 and 100 5-m radius, and were simultaneously levitated and driven acoustically at 20 kHz in water. Mie scattering was used to measure the bubble radius and to monitor its motion before and after the onset of surface instabilities giving rise to shape oscillations. A video imaging system was used to determine the mode of the shape oscillations. [Work supported by NASA.]
Study of liquid drop shape oscillations with an automatic image analysis system
Authors: Apfel Robert E. , Holt R. Glynn , Tian Yuren
Published: October 2005

Droplet shape oscillations induced by acoustic radiation force can be applied to investigate liquid surface rheology. During experiments performed on the United States Microgravity Laboratory missions, the droplet shape was recorded both by video and by film cameras. In order to determine the free oscillation frequency and damping constant of droplets, an automatic image analysis system was developed to evaluate the variations of droplet shape versus time. With this system the edges of drops are automatically located frame by frame, and then matched by a polynomial function. The geometric center point, the maximum and minimum diameters, and the droplet aspect ratio are calculated from the fitting results, which give the droplet free oscillation frequency and damping constant. From these two parameters and the droplet size, the surface elasticity and viscosity of surfactant solutions can be evaluated. [Work supported by NASA through JPL, contract 958722.]
A study of the natural frequencies of spherical and distorted bubbles in open cavities
Authors: Prosperetti Andrea , Og̃uz Hasan N. , Zeng Jun
Published: October 2005

The natural frequency of a bubble in an open, liquid-filled cavity is studied. A number of axisymmetric and three-dimensional configurations are considered such as a bubble in a cylindrical tube closed or open at one end and open at the other, a bubble between two parallel plates, a bubble in an open spherical cavity, and others. For bubbles that are smaller than the acoustic wavelength, the incompressible potential flow approximation is adequate. The natural frequency is computed by a boundary integral method. A slightly overexpanded bubble is allowed to relax and oscillate, and its frequency is measured by taking the Fourier transform of the volume pulsations. Alternately, a constant potential over the bubble surface is imposed and the natural frequency is calculated from the resulting volume flow rate of the bubble. These two techniques give nearly identical results for linear oscillations. For each geometry, spherical as well as distorted bubbles are investigated. [Work supported by the Office of Naval Research.]
Determination of seabed statistical properties and their effects on acoustic wave propagation in shallow water
Authors: Turgut Altan , Wolf Stephen N.
Published: October 2005

Genetic algorithms are used to invert statistical properties of sea bottom/sub-bottom from backscattering data. Backscattering from the seabed is calculated using composite roughness model of Jackson etal. [J. Acoust. Soc. Am. 79(5) (1986)], incorporated with the volume scattering model of Stockhausen [NRE Report 63/9 (1963)]. A parametric study indicates that, for given average sound speed and density of the seabed, bottom roughness parameters such as spectral strength and spectral exponent and sub-bottom parameters such as sound-speed variation, vertical correlation length, and horizontal correlation length can be inverted successfully. Complementary sub-bottom measurement techniques such as core sampling, seismic, and tomographic measurements are also discussed. Acoustic calculations using measured seabed inhomogeneities predict significant coupling to the higher-order modes. This coupling manifests itself as an important loss mechanism.
Classification of lake bottom sediments by neural networks using wideband echo signals
Authors: Ma Yuanliang , Wang Z. Y. , Gimenez G. , Vray D.
Published: October 2005

The paper presents a method of lake bottom sediment classification by artificial neural networks (ANN) using wideband echo signals. The samples to be classified were acquired by experiments at Lake Geneva. There are five types of sediments, namely, silt, rocks, pebbles, sand, and a mixture of sand and gravel. The pattern features are extracted from spectra of echo signals in subband energy expression. Different subband divisions for frequency-domain feature extraction are compared and it is shown that the contant Q method provides better results in comparison with the constant bandwidth method. Using the constant Q method in association with a BP-type locally connected neural network, 85.1% correct classification in average has been achieved for a testing data set. Wideband echo signals have outstanding superiority for classification in comparison with narrow-band signals. It contains more information representing the physical and architectural features of targets. The neural network ultilizes the information through careful optimization and provides a performance improvement up to 10%.
Fractal timing of phonemic transforms
Authors: Tuller Betty , Ding Mingzhou , Kelso J. A. Scott
Published: October 2005

The focus of the present work is the timing pattern of perceptual change elicited by multiple repetitions of a syllable (the verbal transformation effect; Warren and Gregory, 1958). It is shown that the distribution of the dwell time, the time spent perceiving a given phonemic form before switching to another form, obeys a power law with an exponent valued between 1 and 2. This result is robust, occurring for meaningless syllables and for English words of different initial phonemic salience, and for presentations as short as 1000 syllable repetitions or as long as 10 000 repetitions. Thus within this paradigm there is no characteristic time scale for perceptual change. [Work supported by NIDCD Grant No. 5-R29-DC00411, NIMH Grant No. 5-R01-MH42900, and BRSG Grant No. NSS 1-SO7-RR07258.]
Speech variability in the TIMIT database
Authors: Paneras Demetrios E. , Bitar Nabil N. , Espy-Wilson Carol Y.
Published: October 2005

In an effort to understand variability occurring in fairly casual speech, two experiments were conducted using the TIMIT test data which consist of 1680 sentences spoken by 112 males and 56 females. In the first experiment, the TIMIT phonetic transcriptions were compared automatically against the phonemic transcriptions provided in an on-line dictionary. In the second experiment, the TIMIT phonetic transcriptions were mapped to the broad classes vowel, sonorantconsonant, stop, fricative, and affricate, and compared to the output of an automatic broad classifier. For the types of variability found, the analysis includes: (1) the contexts in which they occur, (2) the frequency at which they occur, and (3) differences in their manifestations as a function of dialect region. Phonological rules generated from this study are discussed in the context of those cited in the literature.
Application of wavelet transform to fluctuation based processing
Authors: George Jacob , Wagstaff Ronald A.
Published: October 2005

Recently the topic of wavelet analysis has received considerable attention from physicists, engineers, and mathematicians [C. K. Chui, AnIntroductiontoWavelets (Academic, New York, 1992)]. One well-known feature of a wavelet transform is the choice of a flexible time window which automatically narrows when observing high-frequency phenomena and widens when studying low-frequency environments, in contrast to a fixed window in traditional Fourier transforms. Alternately, the wavelet transform can be viewed as a two-parameter representation of a signal. These features have been used with advantage in time-frequency analyses [Badiey etal., ‘‘Shallow water acoustic/ geoacoustic experiments at the New Jersey Atlantic Generating Station site,’’ J. Acoust. Soc. Am. 96, 3593–3604 (1994); Drumheller etal., ‘‘Identification and synthesis of acoustic scattering components via the wavelet transform,’’ J. Acoust. Soc. Am. 97, 3649–3656 (1995)]. Fluctuation based processing which has recently been developed at NRL, takes advantage of the time fluctuations of the signal to improve the signal/noise ratio and to enhance signal detection for several frequencies. The improvements in such processing due to the use of wavelet representation will be discussed. [Work supported by ONR.]
A first approximation to wavelet transform
Authors: Romero José , Cerdá Salvador
Published: October 2005

The wavelet transform is a tool usually used to analyze time-varying spectrum signals. In this work a simple algorithm was presented to evaluate the integrals involved in wavelet transform. In the analysis of time-varying spectrum signals different methods are used. One of them is the short-time Fourier transform (STFT). This method was presented and its problems were mentioned. To solve them, the discrete wavelet transform (DWT) and the Weyl–Heisenberg wavelet transform (WHT) were introduced. To compute the DWT an algorithm was presented that replaced the integrals by a sum in analogy to the case of FT, and also permitted computation of the WHT. Some signals were analyzed using three functions as the mother wavelet: the Haar function, the Mexican hat function, and the Morlet function. The analyzed signals were a 1860-Hz tone, a sweep simulated with cos(at2+b), an impulsive signal, and an example on FFT which did not work correctly. Results were graphically represented and comments on every case were realized. It was found that in different cases, it was best to use the mother wavelet functions.
The application of wave field dislocations to the characterization of objects using scattered pulsed sound
Authors: Brewster James R.
Published: October 2005

Wave field dislocations, so named because of their morphological similarity to dislocations in crystals, are singular lines in the phase of a wave. It will be demonstrated that they can be applied to the characterization of sound fields that exhibit a complicated spatial variation. Dislocations have been identified experimentally in wave fields formed by the scattering of pulsed ultrasound from rough surfaces and from the internal microstructure of metals. The statistics of these dislocations can be correlated with the length scale of the features responsible for the scattering. Experiments were performed using pulsed ultrasound, of central frequency 20 MHz, reflected from the specimen and detected in water immersion using a coincident source–receiver. The phase of the wave is defined in terms of the position of the wave crests in the signal detected as a function of time at a fixed receiver position.
Aeroacoustic wideband array processing for detection and tracking of ground vehicles
Authors: Pham Tien , Sadler Brian M.
Published: October 2005

Wideband array processing using a steered covariance matrix (STCM) [H. Wang and M. Kaveh, IEEE Trans. ASSP 33, 823–831 (1985)] was implemented and evaluated with experimental data from a small baseline aeroacoustic sensor array. The nonstationary character of acoustic signatures from maneuvering vehicles requires harmonic association and adaptive selection of an operating-frequency set for the STCM on a data-block by block basis. The sensor outputs are processed so that all selected frequencies with the same direction of arrival (DOA) have the same rank-one representation in the steered covariance matrix. This matrix was used in the steered minimum variance (STMV) method [J. Krolik, in AdvancesinSpectrumAnalysisandArrayProcessing, Vol. II, Chap. 6 (Prentice-Hall, Englewood Cliffs, NJ, 1991)] to accomplish adaptive direction finding. Processing gain and corresponding improvement of accuracy in the DOA estimates was observed when compared to narrow-band subspace methods such as ESPRIT. The STMV DOA estimates are more stable and more reliable than the narrow-band methods. This is especially evident in the multivehicle case with a nearby vehicle much louder than more distant ones.
Application of narrow-band and broadband signal processing techniques to the acoustic detection and localization of aircraft
Authors: Ferguson Brian G.
Published: October 2005

The acoustic spectrum of a transiting aircraft is shown to be ‘‘time varying’’ when received by a stationary observer. This phenomenon is an example of the Doppler effect, which is exploited to localize aircraft having narrow-band lines in their source spectra; for example, propeller-driven aircraft and helicopters. For the present case of a turboprop aircraft, the application of time-varing spectral analysis techniques to the acoustic data from a single sensor enables the instantaneous propeller blade rate to be estimated at short-time intervals during the aircraft transit. The temporal variation of the Doppler blade rate is required as an input to the localization algorithm, which provides estimates of the aircraft’s speed and range at the closest point of approach, as well as the source (or rest) frequency of the propeller blade rate. Next, a broadband cross-correlation technique is applied to the acoustic data from a pair of spatially separated microphones to demonstate the automatic detection of an aircraft transit. Short integration times and Doppler compensation are required to track the transit of a fast aircraft.
Simulation of real-time recognition of marine-mammal sounds by a multiple-resolution Bayesian classifier
Authors: Hayward Thomas J.
Published: October 2005

A multiple-resolution, Bayesian statistical approach to classification [J. Acoust. Soc. Am. 96, 3312(A) (1994)] is tested on simulations of marine-mammal sounds received in an ocean waveguide. Training data for several types of marine-mammal vocalizations are obtained from both the Woods Hole Oceanographic Institution SOUND database and the Naval Research Laboratory Dual Use Acoustics Center (DUAC) database. Sound samples not in the training set are then presented to the classification algorithm in a simulation of sound emanating from multiple marine-mammal sources [J. Acoust. Soc. Am. 97, 3371(A) (1995)]. This simulation incorporates modeling of ocean acoustic propagation effects on the vocalization waveforms. When combined with event detection, the classification algorithm achieves near-real-time speed in classification of several types of marine-mammal sounds. [Work supported by ONR.]
Experimental studies of the effect of non-Newtonian constitutivity on propagation of sine waves in liquids
Authors: Raichel Daniel R. , Takabayashi Ken
Published: October 2005

According to the Raichel–Kapfer theory [J. Appl. Mech. 40 (Series E), 1–6 (1973)], propagation of even the purest sinusoidal sound wave through a fluid will cause higher harmonics to appear, due to the nonlinear nature of fluid motion. Moreover, any deviation of the fluid’s constitutivity from Newtonian behavior will cause these harmonics to change in their amplitudes with respect to the fundamental. In the effort to verify these effects, a sonic viscometer was constructed and operated. The device consisted of a 15-cm-diam, 182-cm-long tube that is filled with specimen fluid. A series of pure sine waves, varied octave-wise from 500 Hz to 8 kHz, was introduced through an electromagnetic driver at one end of the tube into distilled water first and then into a 1% solution of polyethylene oxide which effectively rendered the water non-Newtonian. Fast Fourier transform analyses of the signals intercepted by a hydrophone at the other end of the tube indicate that pronounced changes occur in the second and third harmonics, as predicted by the Raichel-Kapfer theory. [Work supported by the NY State Science Foundation and the Howard Hughes Medical Foundation.]
Experimental measurements of three-dimensional underwater sound propagation over a variable bathymetry laboratory scale model
Authors: Riley Joseph M. , Glegg Stewart A. L. , Deane Grant B.
Published: October 2005

Experimental measurements have been conducted giving a complete survey of the acoustic field from a point source in a three-dimensional shallow-water environment. The measurements have been conducted over a 1/10 000th scale model of the Santa Lucia Escarpment off the coast of California. The results of the experiment show three-dimensional propagation effects and areas of modal cutoff in the shallow-water regions. In addition, a discontinuity in the acoustic field was observed for propagation over a joint in the model. This observation has implications for localizing changes in seafloor composition from propagation measurements. Numerical predictions of the acoustic field for selected tracks in the survey show good agreement with the experimental results. [Work supported by the Office of Naval Research, Ocean Acoustics Program.]
Stochastic inhomogeneous volume model for fine-scale sediment layering
Authors: Oba Roger M.
Published: October 2005

An inverse relation of bottom loss to frequency was successfully modeled by random fine-scale sediment layering [C. W. Holland and G. Muncill, J. Acoust. Soc. Am. 94, 1609–1620 (1993)]. A computational method for propagation of the Helmholtz equation in a water column with stochastic volume variation was developed to compute average complex pressure field and average square of the field numerically in a single pass. This model is revised for use in sediment with uncertain layering, assuming negligible shear interaction. A uniform upward refracting sediment has inclusions of fixed thickness, sound speed, and density, but of uncertain vertical spatial distribution. The vertical interlayer spacing is treated as a random variable with gamma distribution. This model also can be used to isolate phenomena associated with density variation versus sound speed variation. [Work supported by the Naval Research Laboratory and the Office of Naval Research.]