bluuebunny/crossref_metadata_2025 huggingface dataset:
A reanalysis of experimental high-frequency spectra using periodic orbit theory
Authors: Delande Dominique , Sornette Didier , Weaver Richard
Published: October 2005

The data, obtained [R. L. Weaver, J. Acoust. Soc. Am. 85, 1001 (1989)] on high eigenfrequencies of small aluminum blocks, is reanalyzed using improved fitting procedures. If the results are quantitatively different from those published previously, they do not significantly modify the main conclusion that fluctuations of the spectrum on a small scale (involving a few mean eigenfrequency spacings) are well described by the model of Gaussian orthogonal ensemble (GOE) of random matrices. In addition, it is shown that, on a larger scale, the spectrum is correlated due to the existence of periodic classical ray trajectories. In other words, the large scale oscillations of the spectrum yield information on the size and shape of the aluminum blocks.
An evaluation of a ray-tracing volume source formulation of wave scattering
Authors: Murch R. D.
Published: October 2005

An evaluation of a ray-tracing volume source formulation of wave scattering is presented. The basis of the formulation is to combine the physically realistic interpretation of propagation as rays with an exact diffractive representation of scattering such as the volume source formulation. The formulation has been used previously in inverse scattering but an evaluation of its accuracy has not been performed for the corresponding direct problem. In this paper the formulation of the technique is formally presented and a numerical evaluation of its accuracy is performed. Results are provided for a variety of cylindrical objects and comparisons are presented with exact results and also results from the Born approximation. The results indicate that indeed dramatic improvements over the Born approximation are possible.
Scattering from a thin random fluid layer
Authors: Zhang Yuan , Weaver Richard L.
Published: October 2005

The problem of a plane wave obliquely incident from a homogeneous ideal fluid upon a random fluid layer is considered and expressions are derived for the diffusely backscattered intensity. The thin layer is taken to have properties that vary only in the two in-plane directions. A first Born approximation is used and the average intensity of the incoherent part of the backscattered wave is found to be proportional to the two-dimensional spatial Fourier transform of the auto- and cross-covariance functions of the layer. Within the confines of the validity of the first Born approximation, therefore, the inverse scattering problem may be straightforward, provided the necessary experimental data of the incoherent wave can be obtained. A sufficient condition to estimate the range in which the second-order term in the Born series can be neglected is also given.
Piezoelectric ceramic mechanical and electrical stress study
Authors: Butler John L. , Rolt Kenneth D. , Tito Frank A.
Published: October 2005

A study of published literature and information from piezoelectric ceramic vendors and underwater sound transducer designers has been undertaken to establish mechanical and electrical operating limits for transducers. It appears that operation up to 3.9–5.9 kV/cm (10–15 V/mil) rms and 69–103 MPa (10–15 kpsi) peak compression is achievable in practical sonar transducers.
Matched-field localization in high noise environments: A reduced-rank signal processing approach
Authors: Riley H. Bryan , Tague John A.
Published: October 2005

A new matched-field source localization technique using generalized likelihood array processing is proposed. The problem is posed as a joint detection and parameter estimation problem in the face of structured noise of unknown power. Recent developments in reduced rank signal processing are exploited to solve it; they yield an algorithm that provides effective interference cancellation, high resolution, a constant false alarm rate detection statistic, and accurate source location estimates. Its performance is tested and evaluated in a simulated shallow water environment. It was found that it yields excellent results at the price of moderate computational overhead as compared to the Bartlett and Capon estimators.
Investigation of low-frequency footfall noise in wood-frame, multifamily building construction
Authors: Blazier Warren E. , DuPree Russell B.
Published: October 2005

An investigation of low-frequency footfall noise in multifamily, wood-frame residential construction has led to the conclusion that, at present, there is no economically practical method of avoiding the perception of ‘‘thuds’’ and ‘‘thumps’’ in rooms beneath the walking surface. The IIC rating of a floor system is meaningless with respect to the perception of these low-frequency components of footfall noise, because the methodology ignores the frequency spectrum below 100 Hz; the peak energy in a footfall spectrum occurs at the fundamental natural frequency of the floor/ceiling system, which with typical light-weight structural framing is usually between 15 and 30 Hz. Although the construction of floated floors, or the addition of carpeting, is effective in attenuating mid- to high-frequency components of footfall noise, the data indicate that the amplitude of floor response at the natural frequency is actually increased. It is believed that this occurs because walking on a more resilient system results in a longer rise-time of the footfall waveform, which permits more low-frequency energy to be coupled into the system. The principal factor controlling the perception of low-frequency footfall noise is the point-stiffness of the structural floor system. In normal light-weight residential construction, the stiffness is usually much less than that required to avoid an audible disturbance. However, such problems are relatively rare in concrete structural floor systems, due to their substantially increased stiffness.
On the acoustical longitudinal vibration modes of finite cylinders
Authors: Bayón A. , Varadé A. , Gascón F.
Published: October 2005

Experimental measurements have been carried out on natural vibration frequencies of steel and aluminum cylinders of diverse radii and lengths in symmetric longitudinal modes. A new method of noncontact detection has been used, based on speckle heterodyne interferometry. As opposed to other authors’ experiments, these experiments do not only include slender specimens but include diameter-to-length ratios in the interval from 0.0156 to 0.6254. A study was performed using the results of the experiment. The relationship between the frequency and some variables of interest were analyzed and the dispersion of the velocity was determined. A systematic dependence of the wave velocity on the diameter was observed, even for small diameter-to-wavelength ratios. The results obtained were compared with the theoretical ones for infinite rods and limits were established for those the commonly used simplified theory may not be applied to. These results can be used to determine the Young’s modulus from the frequencies of the longitudinal modes.
Transmission of bending waves in inter-connected rectangular plates
Authors: Kim Hyun-Sil , Kang Hyun-Joo , Kim Jae-Seung
Published: October 2005

A modal analysis method is developed to study the bending-wave transmission in inter-connected rectangular plates in mid- or high-frequency ranges. The response of the connected plate is described in terms of the modes of the single plate as if each plate were separated by assuming the moments arising at the junctions as external forces. The moments are determined from the equilibrium of the moments and the continuity of the slope at the junctions. The present method does not impose any limitations on the number of connected plates and connection type provided that the directions of the connections are in parallel and the lengths of the connections are equal. The double infinite modal summations are transformed into one finite modal summation only in transverse direction by employing closed forms. It is shown that the driving point mobility of the excited plate approaches that of an infinite plate as frequency becomes higher regardless of the connected plates. The spatially averaged velocities are also compared to the statistical energy analysis results.
Acoustic scattering by submerged cylindrical shell stiffened by an internal lengthwise rib
Authors: Klauson Aleksander , Maze Gérard , Metsaveer Jaan
Published: October 2005

An experimental study of sound scattering by a thin-walled cylindrical shell stiffened by an internal lengthwise rib is presented. The results show that, in the explored frequency band, the positions of the resonance frequencies of the wave S0 are not affected much by the presence of a stiffener. Measurements made during the transient state after the quasiharmonic excitation of the stiffened shell have shown that, at the S0 wave resonance frequencies, backscattering is at its maximum when the rib is located at the vibration node of the shell. On the other hand, when in the total backscattered pressure, forced vibration is also taken into account, the maxima are detected when the rib is located at the vibration antinodes. In the stiffened shell other additional resonances appear which are not excited in the case of an unstiffened shell. These resonances are attributed to the propagation of the flexural type waves which are not detected in an unstiffened shell. In a stiffened shell these resonances appear as a result of the interaction of the rib and the shell at their structural joint. These additional resonances are better observed when the rib is located at the ‘‘illuminated’’ part of the shell which indicates that most of the energy is scattered by the rib and shell joint. In the case of a short-pulse excitation, specular reflections from a joint can be observed. The experimental results correlate very well with the theoretical models.
Power consumption of piezoelectric actuators driving a simply supported beam considering fluid coupling
Authors: Stein Steve C. , Liang Chen , Rogers Craig A.
Published: October 2005

An electromechanical impedance model is applied to the case of a simply supported beam in an infinite rigid baffle with a fluid medium on one side. The effects of the fluid medium are included in the impedance analysis by considering fluid–structure interaction. The use of static and impedance model for structural acoustic analysis is discussed. Various power consumptions of PZT actuator-driven underwater beam structures will be quantified. The analysis discussed in this paper will be used to determine radiated structural acoustic power without using microphones. This work is the first step toward the determination of power requirements for underwater active structural acoustic control.
Focusing performance of epoxy- and air-backed polyvinylidene fluoride Fresnel zone plates
Authors: Sleva Michael Z. , Hunt William D. , Briggs Ronald D.
Published: October 2005

In this paper the focusing performance of epoxy- and air-backed polyvinylidene fluoride (PVDF) Fresnel zone plate (FZP) transducers are investigated. This work is motivated by an interest in constructing integrated, polymer FZP transducers for imaging applications on a silicon substrate using integrated circuit fabrication techniques. While it is well known that using an impedance matched backing facilitates broadband transducer performance, to the authors’ knowledge the effects on the acoustic beam patterns of polymer FZPs have not been reported. A model for the ideal zone plate is also presented, and a general pressure transfer function is derived in order to generate theoretical beam profiles. Epoxy- and air-backed, three-zone FZPs were constructed using 111 μm thick PVDF. The devices were tested in an ultrasound scanning tank while operating at 5 MHz. The focal plane profile for the epoxy-backed device was in good agreement with that predicted for the ideal zone plate. In addition, the epoxy backing was found to dampen higher order radial mode excitation. The radial modes are believed to be responsible for the narrow main lobe and elevated side lobes found in the focal plane profile for the air-backed device.
Acoustic models of fish: The Atlantic cod (Gadus morhua)
Authors: Clay Clarence S. , Horne John K.
Published: October 2005

Acoustic fish models should represent the fish body form. The Atlantic cod were used to model the acoustic scattering function of teleost fish. The model provides a basis for choices of sonar carrier frequencies. Anesthetized live Atlantic cod ranging from 156 to 380 mm (SL) were ‘‘soft’’ x-rayed to image inflated swimbladders and skeletal elements. Maximum body heights and widths were 0.18 and 0.13 of fish lengths. Lengths and diameters of swimbladder were approximately 0.25 and 0.05 of the fish lengths. A series of short-length fluid-filled cylinders were used to represent body flesh. For carrier frequencies above the breathing mode resonance, swimbladders were modeled as a series of short gas-filled volume elements of cylinders. A Kirchhoff-ray approximation was used to compute the high-frequency acoustic scattering. A low mode solution for a gas-filled cylinder was used to compute the low-frequency ‘‘breathing mode resonance.’’ All contributions were added coherently. The scattering lengths ℒ, or target strength=20 log‖ℒ/L0‖ (where L0 is reference length) were sensitive to fish orientation relative to the sonar beam. Theoretical target strengths were compared to the 38-kHz cod data. Agreement was good.
Detection of a submerged object insonified by surface noise in an ocean waveguide
Authors: Makris Nicholas C. , Ingenito Frank , Kuperman William A.
Published: October 2005

A theory is developed and applied to determine whether an object submerged in an ocean waveguide and insonified only by surface-generated noise can be detected with conventional sensing arrays. An expression for the total noise-field covariance of a stratified waveguide with a submerged object present is derived using full-field wave theory. This is evaluated by numerical wave-number integration for a spherical object in a shallow water waveguide. The Cramer–Rao lower bound on detection error is computed for several realistic shallow water scenarios at both low and high frequency. The results indicate that cross-range localization is possible when the array aperture is sufficient to resolve the object scale. This conclusion is supported by beamforming simulations. Range localization is possible at greater distances. However, this requires high correlation between direct and scattered noise fields at the sensor, which is difficult to replicate via matched field processing. In addition, wave theory indicates that high resolution imaging of reflected ambient noise is generally most effective within the deep shadow range of the object. Beyond the deep shadow range, diffractive interference from the total forward field may overwhelm reflections, depending upon the incident noise directional spectrum and measurement range. Overall, present analysis indicates that the proposed detection scheme presses the limits of current technology.
The spectral parabolic equation and three-dimensional backscattering
Authors: Orris Gregory J. , Collins Michael D.
Published: October 2005

Problems involving dependence of the acoustic parameters in depth and one of the horizontal Cartesian coordinates are solved using the cross-range wave-number spectrum and the parabolic equation (PE) method. The self-starter and the two-way PE are used to solve the two-dimensional wave equation that is obtained after transforming to wave-number space. Although the spectral PE solution breaks down for energy that propagates nearly parallel to the cross-range axis, it is accurate in other directions for both outgoing and backscattered energy. The spectral PE is practical for solving large-scale reverberation problems in three dimensions.
First-order perturbation solution for rough surface scattering cross section including the effects of gradients
Authors: Moe John E. , Jackson Darrell R.
Published: October 2005

The transition matrix relating the incident pressure field to the scattered field in a fluid above a rough surface is derived to first order using Rayleigh–Rice perturbation theory, resulting in a general expression for scattering strength. A small region bordered above by the rough surface and below by a horizontal plane intersecting the surface at its lowest point contains a lossy homogeneous fluid. Below this point, the sediment is allowed to be vertically stratified, viscoelastic, or porous, supporting shear or Biot slow waves. Gradients strongly affect the scattering cross section if they cause a substantial portion of the incident energy to be redirected toward the interface.
Noise cancellation and source localization
Authors: Collins Michael D. , Makris Nicholas C. , Fialkowski Laurie T.
Published: October 2005

A noise-canceling processor is developed for matched-field processing problems involving a signal buried in noise. This processor is based on modeling both signal and noise and searching the space of unknown parameters to achieve the best agreement between covariances. The noise-canceling processor reduces to the Bartlett processor in the limit of high signal-to-noise ratio. The examples illustrate the localization of a source obscured by interference from ambient noise or a second source. The noise-canceling processor is also applied to localize a silent object using scattered ambient noise.
A phase function for finding normal mode eigenvalues over a layered elastic bottom
Authors: Tindle C. T. , Chapman N. R.
Published: October 2005

A method is described for the determination of normal mode eigenvalues in shallow water over a layered elastic bottom. The method avoids the usual search for eigenvalues in the complex plane by deriving a complex phase function which is a multiple of π at the normal mode eigenvalues. The path in the complex plane along which the phase function is real gives a simple curve which passes systematically through all the eigenvalues including those for the leaky modes. Along this path the phase function is real and monotonic. The eigenvalues can be found by following this path.
Modeling of low-frequency transmission loss in the central Arctic
Authors: LePage Kevin , Schmidt Henrik
Published: October 2005

The magnitude of low-frequency (10−100 Hz) propagation loss in the central Arctic is known to be larger than predicted by most free surface scattering theories. This high loss is introduced primarily by scattering at the ice canopy, with which the acoustic path interfers regularly due to the presence of a strongly upward refracting surface duct. While distinct feature scattering theories such as boss or elastic keel models predict higher losses, these results are typically too frequency dependent to agree with the data over the entire band of interest. Perturbation theory gives close to the correct frequency dependence, but historically predicts too little loss when the dynamics of the ice canopy is neglected or the ice is assumed to be locally reacting. In this paper it is proposed that when perturbation theory is extended to include scattering of incident acoustic energy into propagating elastic modes in the ice, the resulting expressions correctly predict low-frequency losses measured in the Arctic.
Acoustic scattering from a fluid–elastic-solid interface using the small slope approximation
Authors: Yang Taiqian , Broschat Shira L.
Published: October 2005

In this paper the small slope approximation is applied to acoustic scattering from a randomly rough fluid–elastic-solid interface. Expressions for the zeroth-, first-, and second-order bistatic scattering cross sections are derived. Numerical results are obtained for the zeroth-order small slope approximation for Gaussian and modified power law surface roughness spectra and are compared with those of first-order perturbation theory and the Kirchhoff approximation. The environmental parameters used correspond to those of water–granite, water–basalt, or water–sediment interfaces for lossless media. The small slope results show the complex structure associated with elastic wave scattering, including critical angle and Rayleigh angle structure. For the modified power law, the small slope results agree with those of Monte Carlo simulations performed by Berman [J. Acoust. Soc. Am. 89, 623–636 (1991)]. The study includes a comparison of scattering strengths both with and without the shear wave component. The importance of the shear wave component for a sufficiently rigid solid is illustrated.
Removal of time-varying Doppler using phase tracking with application to ocean warming measurements
Authors: Schumacher Ian , Heard Garry J.
Published: October 2005

Coded signals received by a moving receiver or from a moving source exhibit a time-scaling Doppler effect that can be detrimental to their ability to be correctly decoded. The effect is especially critical for the highly Doppler sensitive pseudo-random noise M sequences frequently used to measure propagation travel times. This paper develops a technique to measure dynamic Doppler effects empirically by tracking the phase of the transmitted carrier, and to remove such effects through interpolation and resampling of the signal. These techniques were very effective for simulated signals and will in the future be employed to help resolve the propagation times of the Heard Island feasibility test data collected by the Canadian receivers.
Predicting the scattering from reflectors and diffusers using two-dimensional boundary element methods
Authors: Cox Trevor J.
Published: October 2005

This paper demonstrates that two-dimensional boundary element methods are fast and efficient techniques for predicting the scattering from reflectors and diffusers. Of particular interest in this study were diffusers used in auditoria. The scattered pressure distributions were closely predicted by the boundary element methods, which is often sufficient for acousticians. The absolute scattering magnitude was not always well predicted. Consequently, two different techniques have been developed which compensate for predicting the inherently three-dimensional problems using two-dimensional methods. The compensations work very well for mid to high frequencies. They also work better for scattering near the geometric scattering angle.
Transient fluid–solid interaction of submerged spherical shells revisited: Proliferation of frequencies and acoustic radiation effects
Authors: Jones-Oliveira Janet B. , Harten Leo P.
Published: October 2005

The exact series solutions for the transient shell displacement and fluid pressure fields resulting from the axisymmetric acoustic loading of a submerged, thin elastic, spherical shell are well known. Plots of the shell displacements, velocities, accelerations, strains, and strain rates have been published previously. Further investigation for the more general prolate spheroidal geometry has elucidated a complex exchange of energy between the structure and the fluid through the kinematic boundary conditions, which is presented herein for the simpler spherical geometry. The importance of the time evolution of the acoustic radiation coupling to the structure is discussed, including phase information. A comparison of the unloaded versus fluid-loaded frequencies for an example problem demonstrates the ‘‘softening’’ effect of the fluid on the structural response and reveals it to be more complex than simple damping. The reloading of the shell due to radiation in the fluid introduces a proliferation of frequencies in the structural response which is characteristic of fluid–solid interaction problems. The computer algebra system PARAMACS is used to perform the analytical and numerical calculations.
Resonance identifications of a solid axisymmetric finite length target
Authors: Maze Gérard , Décultot Dominique , Lecroq Florence , Ripoche Jean , Bao Xiao-Ling , Überall Herbert
Published: October 2005

Acoustic resonance scattering from a water-immersed, solid tungsten carbide target in the form of a finite-length circular cylinder terminated by two hemispherical endcaps has been studied experimentally, and analyzed theoretically. The resonance frequencies have been determined from the condition of phase matching of the generated surface waves encircling the object; for the surface waves propagating over its cylindrical portion in the axial direction, the dispersion has been properly taken into account, as well as that of surface waves on the spherical surfaces. Surface displacements corresponding to the standing waves at each resonance were determined, and were used to calculate the angular patterns of the scattered acoustic field, in excellent agreement with the observed angular distributions. The pattern of lobes is found to provide information on the mode N of the standing surface waves, although in a less straightforward fashion than this had been the case in previous studies for the simple examples of spheres or infinite cylinders.
The scattering of a low-angle pulse beam from seafloor volume heterogeneities
Authors: Swift Stephen A. , Stephen Ralph A.
Published: October 2005

A numerical scattering chamber is used to study the scattering of low-grazing-angle geoacoustic energy from a flat, basaltic seafloor with underlying volume heterogeneities of various length scales (0.1≤ka≤4, where k is the wave number and a is the length scale of the heterogeneity). The two-dimensional scattered field is computed by the finite-difference method for an incident Gaussian pulse beam at 15° grazing angle (total internal reflection). For a deterministic model the scattering function is not monotonic with respect to angle, such as predicted by Lambert’s law. Peaks in the scattering function (up to 10 dB above background scattering levels) occur at angles that correspond to forward and backward compressional and shear head wave propagation. The scattered field is generated by primary diffractions directly into the water column, secondary diffractions from compressional and shear body waves and interference waves, and tertiary diffractions from interface waves that have converted into shear body waves. For the models studied, monostatic backscatter levels are largest for ka of about 1. The levels are −40 dB for no gradient in the mean subbottom velocity profile and about −48 dB for a gradient in the mean profile.
Analysis of acoustic elements and syntax in communication sounds emitted by mustached bats
Authors: Kanwal Jagmeet S. , Matsumura Sumiko , Ohlemiller Kevin , Suga Nobuo
Published: October 2005

Mustached bats, Pteronotus parnellii parnellii spend most of their lives in the dark and use their auditory system for acoustic communication as well as echolocation. The sound spectrograms of their communication sounds or ‘‘calls’’ revealed that this species produces a rich variety of calls. These calls consist of one or more of the 33 different types of discrete sounds or ‘‘syllables’’ that are emitted singly and/or in combination. These syllables can be further classified as 19 simple syllables, 14 composites, and three subsyllables. Simple syllables consist of characteristic geometric patterns of CF (constant frequency), FM (frequency modulation), and NB (noise burst) sounds that are defined quantitatively using statistical criteria. Composites consist of simple syllables or subsyllables conjoined without any silent interval. Most syllable types exhibit a large intrinsic variation in their physical structure compared to the stereotypic echolocation pulses. Syllable domains are defined on the basis of multiple parameters, although these can be collapsed onto three dimensions that capture 99% of the measured variation among different types of syllables. Temporal analysis of multisyllabic constructs reveals several syntactical rules for syllable transitions.
Marine mammal call discrimination using artificial neural networks
Authors: Potter John R. , Mellinger David K. , Clark Christopher W.
Published: October 2005

Recent work has applied a linear spectrogram correlator filter (SCF) to detect bowhead whale (Balaena mysticetus) song notes, outperforming both a time-series-matched filter and a hidden Markov model. The method relies on an empirical weighting matrix. An artificial neural net (ANN) may be better yet, since it offers two advantages; (i) the equivalent weighting matrix is determined by training and can converge to a more optimal solution and (ii) an ANN is a nonlinear estimator and can embody more sophisticated responses. A three-layer feed-forward ANN is ideally suited to this application and has been implemented on 1475 sounds, of which 54% were used for training and 46% kept as ‘‘unseen’’ test data. The trained ANN error rate was 1.5%, a twofold improvement over previous methods. It is shown that ANN hidden neurons can be interrogated to reveal the operating paradigm developed during training. The function of each of these neurons can be determined in terms of spectrographic features of the training calls. Furthermore, the operating paradigm can be controlled and training time reduced by assigning specific recognition tasks to hidden neurons prior to training, rather than initiating training with randomized weights. The ANN is compared to the SCF and the role of the ‘‘hidden’’ neurons and equivalent weighting matrices are discussed.
A comparison of content-masking procedures for obtaining judgments of discrete affective states
Authors: Friend Margaret , Farrar M. Jeffrey
Published: October 2005

The purpose of this article is to investigate observers’ use of acoustic cues to arrive at judgments of the speaker’s affective state and to address current methodological limitations. Ninety-nine female undergraduates rated the level of excitement, happiness, and anger of speech stimuli under three content-masking procedures: low-pass filtering, random splicing, and reiterant speech. Each procedure preserves some forms of acoustic information while disrupting or degrading others. As predicted, the content-masking procedures generated bias in observers’ affective ratings. Results are discussed in terms of the efficacy of the content-masking procedures and implications for the study of acoustic cues to speaker affect.
The role of short-term and long-term auditory storage in processing spectral relations for adult and child speech
Authors: Ohde Ralph N. , Perry Anne H.
Published: October 2005

The processes involved in the perception of spectral change between the nasal murmur and the vocalic transition for speakers of different ages were assessed before and after disruption of the variation in spectra between these elements. Three children, aged 3, 5, and 7, and an adult female and male produced consonant–vowel (CV) syllables consisting of either [m] or [n] followed by [i] or [u]. In one condition (spectrally noncontiguous), the acoustic information surrounding the region of spectral change was digitally removed and in another condition (spectrally contiguous) this portion of the signal was retained. In both of these conditions, intervals of silence ranging from 0 to 2000 ms were inserted between 50-ms segments of murmur and vocalic transition. These gap duration conditions were then presented to adult listeners for the identification of the nasal. Across speakers, the results for the spectral contiguous condition support a primary mechanism in the perception of spectral relations that is mediated by processes within short-term auditory memory, but the results for the spectral noncontiguous condition revealed little consistent support for either short-term or long-term memory processes.
Determination of sagittal tongue shape from the positions of points on the tongue surface
Authors: Kaburagi Tokihiko , Honda Masaaki
Published: October 2005

This paper describes a method for determining the shape of the midsagittal tongue contour from the positions of points on the tongue surface. The positions of the points and the tongue shape were measured simultaneously by using an alternating magnetic field device and an ultrasonic B-mode scanner for continuous speech utterances. A comparison between the magnetic and the ultrasonic data revealed that the average measurement difference between the two types of data was 1.16 mm. The shape of the tongue contour was then represented by multivariable linear regression of the magnetically determined positions. The results of the regression analysis showed that the tongue contour was estimated, from four positions on the tongue, with an average estimation error of 1.24 mm. This estimation error could be reduced to 0.84 mm when there was no measurement error between the magnetic and the ultrasonic data, and it was further reduced to 0.43 mm when the receiver coils of the magnetic device were positioned optimally on the tongue. It was also shown that the number of data frames for calculating the regression coefficients could be reduced, while maintaining the estimation accuracy, by appropriately selecting data frames. Finally, the tongue shape was estimated successfully for several phonemes from the magnetically determined positions, thus demonstrating the usefulness of this method for observing the articulatory configuration of the tongue.
Functional brain imaging and hearing
Authors: Elliott Lois L.
Published: October 2005

Functional brain imaging techniques such as PET, SPECT, and functional MRI have frequently been applied to the study of speech, language, and cognition, but have seldom been used in investigations of hearing. Even the limited research that combines functional brain imaging and acoustic stimuli has often been concerned with processes other than audition, such as attention. This paper provides brief descriptions of these currently available functional brain imaging procedures and gives examples of what may be learned about hearing from their applications. Possible reasons for the limited use of functional brain imaging in studying hearing are explored because attention to these issues may enhance interest in the use of brain imaging for investigating the neurophysiology of hearing. Several potential research questions that apply functional brain imaging while measuring psychoacoustic performance are considered briefly and strategies for increasing brain imaging research on psychoacoustic topics are discussed.
The application of frequency and time domain kurtosis to the assessment of hazardous noise exposures
Authors: Lei Sheau-Fang , Ahroon William A. , Hamernik Roger P.
Published: October 2005

Five computer-synthesized broadband noises, each having the same average spectrum and the same unweighted Leq of 100 dB SPL but very different temporal structures, were used to produce hearing loss in chinchillas. Despite the same exposure energies and spectra, each noise exposure produced a different magnitude and frequency distribution of hearing loss and sensory cell loss. The results indicate that the statistical properties of a signal are important in the determination of hearing loss. When the audiometric and histological results are compared to a metric based upon kurtosis measured in the time and the frequency domain for each exposure, there is a clear indication that these statistical metrics are good predictors of the relative magnitude and frequency distribution of the acoustic trauma.
Effect of compression ratio in a slow-acting compression hearing aid: Paired-comparison judgments of quality
Authors: Neuman Arlene C. , Bakke Matthew H. , Hellman Sharon , Levitt Harry
Published: October 2005

Paired-comparison judgments of quality were obtained from 20 hearing-impaired listeners (half with a small dynamic range and half with a large dynamic range) for speech-in-noise (vent, apartment, and cafeteria) processed through a slow-acting compression hearing aid. Compression ratio was varied (1, 1.5, 2, 3, 5, and 10:1). Compression threshold, attack time, and release time were fixed. Sound quality judgments were significantly affected by compression ratio, noise, and dynamic range. Preference decreased with increasing compression ratio. The selection of compression ratios ≤2:1 was significantly higher than of compression ratios ≳3:1. Less compression (no compression or 1.5:1) was preferred with the highest level noise (cafeteria noise) than with the lower level noises (vent or apartment). In particular, the small dynamic range group preferred compression with the vent and apartment noises (noise below the compression threshold), but preferred a linear hearing aid with the cafeteria noise (above the compression threshold). The large dynamic range group showed a slightly greater preference for the linear hearing aid for all three noises.
Automatic discrimination of phonetically relevant and irrelevant vowel parameters as reflected by mismatch negativity
Authors: Aaltonen Olli , Eerola Osmo , Lang A. Heikki , Uusipaikka Esa , Tuomainen Jyrki
Published: October 2005

An auditory event-related brain potential called mismatch negativity (MMN) was measured to study the perception of vowel pitch and formant frequency. In the MMN paradigm, deviant vowels differed from the standards either in F0 or F2 with equal relative steps. Pure tones of corresponding frequencies were used as control stimuli. The results indicate that the changes in F0 or F2 of vowels significantly affected the MMN amplitudes. The only variable significantly affecting the MMN latencies was sex which, however, did not have any effect on the amplitudes of the MMN. As expected, the MMN amplitudes increased with an increase in the acoustical difference between the standards and the deviants in all cases. On the average, the amplitudes were lower for the vowels than for the pure tones of equal loudness. However, in vowels, minor frequency changes in F0 produced higher MMN amplitudes than similar relative changes in F2. It was also noted that even the smallest and phonetically irrelevant change in F2 was detected by the MMN process. In overall, the results demonstrate that the MMN can be measured separately for F0 and F2 of vowels, although the MMN responses show large interindividual differences.
Bubble recycling and ultrasonic cell lysis in a stationary exposure vessel
Authors: Brayman Andrew A. , Azadniv Mitra , Miller Morton W. , Chen Xucai
Published: October 2005

An exposure system producing interleafed pulses of 1-MHz ultrasound from balanced, opposing transducers was used to test the bubble recycling hypothesis (as formulated with respect to rotating exposure vessels) in a stationary exposure vessel containing P388 cell suspensions. Cell lysis was measured in cell suspensions which had been exposed or sham-exposed to 1-MHz ultrasound (5 W/cm2 spatial peak pulse average intensity) delivered in continuously alternating, opposing pulses. The opposing pulse cycle frequency (i.e., gating frequency) varied from 0.1 Hz to 100 kHz, corresponding to single pulse durations ranging from 5 μs to 5 s. Unequivocal support for the bubble recycling hypothesis was obtained. Lytic yield increased as the gating frequency increased, passing through a maximum at gating frequencies of 100 Hz–1 kHz. As the gating frequency increased further, lytic yield declined rapidly. The results are discussed in relation to recent theoretical estimates of bubble translation speeds in an ultrasound field, and are found to be consistent with those estimates.
A comparative study of human and parrot phonation: Acoustic and articulatory correlates of vowels
Authors: Patterson D. K. , Pepperberg I. M.
Published: October 2005

General acoustic and articulatory parallels between human and avian production of human vowels have been identified. A complete set of vowels from an African Grey parrot (Psittacus erithacus) and a limited set from a Yellow-naped Amazon parrot (Amazonica ochrocephala auropalliata) have been analyzed. Comparisons of human and avian acoustic parameters demonstrated both differences (e.g., absolute values of first formant frequencies) and similarities (e.g., separation of vowels into back and front categories with respect to tongue placement) in acoustic properties of avian and human speech. Similarities and differences were also found in articulatory mechanisms: Parrots, for example, use their tongues in some but not all the ways used by humans to produce vowels. Because humans perceive and correctly label vowels produced by psittacids despite differences in avian and human articulatory and acoustic parameters, the findings (a) are consistent with research that demonstrates the flexibility of vowel perception by humans and (b) suggest that the perceptual discontinuities that are exploited by speech may be basic to vertebrates rather than to mammals.
Perception of vowel height: The role of F1–F distance
Authors: Hoemeke Kathryn A. , Diehl Randy L.
Published: October 2005

Perceived vowel height has been reported to vary inversely with the distance (in Bark) between the first formant frequency (F1) and the fundamental frequency (F0) [H. Traunmüller, J. Acoust. Soc. Am. 69, 1465–1475 (1981)]. Syrdal and Gopal [J. Acoust. Soc. Am. 79, 1086–1100 (1986)] observed that naturally produced [+high] and [−high] vowels tend to divide at a critical F1–F0 distance of 3–3.5 Bark, corresponding to the bandwidth of the ‘‘center of gravity’’ effect [L. Chistovich and V. Lublinskaja, Hear. Res. 1, 185–195 (1979)]. In the present study, listeners identified three sets of synthetic vowels varying orthogonally in F1 and F0 and ranging from /i/–/i/, /i/–/ε/, and /ε/–/æ/. For the /i/–/ε/ set, which corresponds to the [+high]/[−high] distinction, there was a relatively sharp identification boundary located at an F1–F0 distance of 3–3.5 Bark. However, for the /ε/–/æ/ and /i/–/i/ sets, which occupied regions where the F1–F0 distance was always greater than or always less than 3 Bark, vowel labeling varied more gradually as a function of F1–F0 distance. Also, F1–F0 distance was a better predictor of labeling performance than F1 alone only for the /i/–/ε/ set. Possible sources of the F1–F0 distance cue for vowel height are discussed.
Variability control in speech production tasks performed by adults and children
Authors: Smith Bruce L. , Kenney Mary Kay
Published: October 2005

Eighteen adults and 12 children, ranging from 7 to 11 years of age, participated in a study that investigated their abilities to control the temporal variability of their speech. For both the adults and the children, few substantive differences in performance were observed when considering control data versus findings from an experimental task in which they were specifically instructed to be as consistent as possible in producing various stimuli. Although some subjects did show reduced variability in the experimental condition, there was little evidence that such decreases typically represented more than random effects. In general, the results suggest that when producing multiple repetitions of words and short phrases, adults and 7–11-year-old children are essentially as consistent as they can be, whether specifically attempting to minimize variability or not. The basis for this could be that even in control conditions, subjects may perform at or near optimal levels of consistency across productions.
The perception of frequency peaks and troughs in wide frequency modulationsa)
Authors: Demany Laurent , McAnally Kenneth I.
Published: October 2005

This work was concerned with the perception of ‘‘instantaneous pitch’’ in continuously frequency modulated sounds. In experiment 1, a 70-dB sinusoidal carrier, close to 1 kHz, was modulated by the exponential of periodic functions corresponding to the sum of a few sinusoids [e.g., sin(at)+sin(3at)]. Each modulation had a fundamental frequency (a/2π) of 1.5 Hz and was symmetric on the dimensions of time and log frequency. Thirty listeners identified discrete melodic motifs within these stimuli. The pitches of the identified notes mainly corresponded to the local frequency maxima; generally, the local minima were not heard as auditory ‘‘events’’ (pitch singularities). A similar perceptual asymmetry was not observed for comparable sequences of discrete tones. In experiments 2–4, frequency difference limens were measured for the maxima and minima of continuous frequency modulations, using an adaptive forced-choice method. Sinusoidal carriers were modulated by the exponential of one cycle of a 5-Hz cosine function, starting at phase π or phase 0 and giving an overall frequency swing of about 0.5 oct. For maxima and minima around 1 kHz, frequency shifts of maxima were better detected than frequency shifts of minima, by an average factor of 2. Generally, this asymmetry did not decrease as a function of subjects’ training in the discrimination task, and was still present when frequency minima were given a 6-dB intensity advantage over frequency maxima. No explanation was found for the advantage of frequency maxima with respect to perceptual salience (experiment 1) or discriminability (experiments 2–4).
An indication for spatial integration in a non-Pacinian mechanoreceptor system?
Authors: Muijser H.
Published: October 2005

It is generally accepted that threshold sensitivity for cutaneous vibrational stimuli has a Pacinian component and a non-Pacinian component. While the Pacinian receptor system exhibits spatial integration, such a property has, until now, not been found in any of the non-Pacinian systems. The present measurements of vibration sensitivity for stimuli with spatial contrast in six subjects revealed that at low frequencies (20–80 Hz) the threshold for a matrix of tiny pins is 13 dB lower than the threshold for a single pin, thus suggesting spatial integration in at least one class of non-Pacinian receptors. It is remarkable that the low threshold for matrix stimuli was found under the condition that adjacent rows of pins vibrated with opposite phase while the threshold for a matrix of pins all vibrating with equal phase was similar to the threshold for a single vibrating pin.
Psychophysical and physiological forward masking studies: Probe duration and rise-time effects
Authors: Turner Christopher W. , Relkin Evan M. , Doucet John
Published: October 2005

To determine if the amount of forward masking observed in single auditory-nerve fibers of the chinchilla was sufficient to account for the amount of masking observed behaviorally in humans, thresholds for the detection of several types of probe signals following a forward masker were measured in both behavioral and physiological experiments. It is necessary to use the same probe stimulus characteristics in both behavioral and physiological experiments to make valid comparisons between the two measures of forward masking. Experiment 1 was behavioral and used human listeners. Two types of probe signals were used, differing in overall duration and rise/fall times. The two probes yielded different growth of masking functions. These results further demonstrate that forward masking characteristics in behavioral experiments are critically dependent upon the parameters of the probe signal used. Experiment 2 was physiological and used chinchillas. The amount of masking for high-level maskers using the same two probe types in a physiological ‘‘forced-choice’’ experiment are presented. In contrast with the behavioral results, there was little or no difference in the amounts of masking observed for the two probes. In addition, the amounts of masking observed in some auditory-nerve fibers were considerably smaller than those observed behaviorally. These experiments further demonstrate that the amount of forward masking observed in single auditory-nerve fibers is inconsistent with that observed behaviorally.