bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of tongue positions: Language-specific and cross-linguistic models
Authors: Jackson Michel T. T.
Published: October 2005

A factor-analytic model, PARAFAC, has been shown to yield highly significant and interpretable results when applied to the analysis of tongue shapes in particular languages. However, the forms of the solutions differ from language to language. A conceptual model that provides an account for cross-language variability in terms of coordinative structures that may vary in a language-specific manner is developed. This model rationalizes both the success of the PARAFAC procedure within languages and the poor cross-language replicability of PARAFAC solutions. We consider methods for quantitatively comparing the results of PARAFAC analyses of data from different languages using data from Icelandic and English as a test case. A cross-language factor solution that accounts for 90% of the variance in tongue position measurements is presented and interpreted in terms of the conceptual model.
Sound scattering from a randomly rough fluid–solid interface
Authors: Dacol D. K. , Berman D. H.
Published: October 2005

A general formalism for acoustic scattering from a fluid–elastic solid interface is developed. The theory parallels Waterman’s work [P. C. Waterman, J. Acoust. Soc. Am. 45, 1417 (1969)], based on the extinction theorem, for acoustic scattering from impenetrable surfaces. This formalism is then used to study the scattering of sound waves from a randomly rough fluid–solid interface by using perturbation theory to solve the equations for the scattering amplitudes to second order. The Watson–Keller renormalization ansatz [J. G. Watson and J. B. Keller, J. Acoust. Soc. Am. 74, 1887 (1983)] is then used to account for some multiple scattering effects beyond double scattering. A numerical study is presented comparing acoustic scattering in the fluid from a fluid–solid interface with acoustic scattering in the same fluid from a hard, impenetrable surface (Neumann boundary condition). Substantial differences between the two cases are found. Besides the expected acoustic energy loss by transmission into the solid, it was also found that the angular distribution of the remaining acoustic energy that is reflected and scattered by the fluid–solid interface differs greatly from the hard impenetrable surface case, especially near grazing incidence and scattering angles.
Numerical evaluation of errors associated with the measurement of acoustic impedance in a free field using two microphones and a spectrum analyzer
Authors: Champoux Yvan , L’Espérance A.
Published: October 2005

This article investigates numerically several sources of errors associated with the measurement of acoustic impedance using the two-microphone method in a free field. This method is based on the evaluation of the acoustic velocity from the pressure gradient. For impedance measurement, the finite approximation, phase mismatch, effective microphone separation, and probe localization errors are analyzed. Once it is known how to calculate the exact impedance above an absorbing plane, the influence of the assumed wave propagation type on the calculation of the material impedance is then investigated. Finally, an example of the useful range of validity of the method is presented.
The photoacoustic effect generated by a spherical droplet in a fluid
Authors: Diebold G. J. , Westervelt P. J.
Published: October 2005

In general, the absorption of amplitude-modulated radiation by a body results in heating and a subsequent thermal expansion that gives rise to the emission of sound waves. Here, the properties of sound waves emitted by uniformly heated spherical droplets are found as a frequency domain solution to a boundary-value problem for the acoustic pressure. The expression for the pressure is Fourier transformed to give the time domain pressure response to a delta function light pulse. Owing to the different sound speeds and densities in the sphere and its surrounding medium, the effects of reflection, dispersion, and phase cancellation can be seen in the acoustic signal.
Methods of chaos physics and their application to acoustics
Authors: Lauterborn W. , Parlitz U.
Published: October 2005

This article gives an introduction to the research area of chaos physics. The new language and the basic tools are presented and illustrated by examples from acoustics: a bubble in water driven by a sound field and other nonlinear oscillators. The notions of strange attractors and their basins, bifurcations and bifurcation diagrams, Poincaré maps, phase diagrams, fractal dimensions, scaling spectra, reconstruction of attractors from time series, winding numbers, as well as Lyapunov exponents, spectra, and diagrams are addressed.
Detection of fluid velocity and hydroacoustic particle velocity using a temperature autostabilized nonlinear dielectric element (TANDEL)
Authors: Rittenmyer Kurt M. , Alexandrakis George C. , Dubbelday Pieter S.
Published: October 2005

A ferroelectric sensor operated in the temperature autostabilized mode was developed for the measurement of the particle motion in hydroacoustic fields. The sensor is a capacitorlike element constructed from antimony sulfur iodide (SbSI) single crystals and SbSI–polymer composites. The device is operated slightly above the Curie point of SbSI, which is approximately 20 °C. Using a Schering bridge, the element is heated by driving it through the hysteresis cycle. The heat transferred to the surrounding fluid is related to the motion of the fluid. The technique was applied to the measurement of a constant velocity flow field and to a low-frequency acoustic field. In the case of the constant velocity flow field, an exponential relationship between fluid velocity and sensor voltage was observed. For acoustic fields, the response of the sensor decreased sharply with frequency above 100 Hz. The acoustic particle velocity could be measured to a frequency around 1 kHz.
Morphology of the cochlear nerve in Sprague-Dawley and Brown Norway rats
Authors: Hoeffding Virginia , Feldman Martin L.
Published: October 2005

Cochlear nerve morphology was studied in young adult albino (Sprague-Dawley) and pigmented (Brown Norway) rats. Analysis of the material included counts of normal and degenerating fibers and of glial cell nuclei, and measurements of vascularity and of the nerves’ cross-sectional areas. The median number of normal fibers in the Sprague-Dawley rats was 21 216, and, in the Brown Norway rats, it was 20 186. There were no statistically significant differences between the two strains in numbers of normal fibers, degenerating myelin sheaths, or glial cell nuclei, or in the cross-sectional areas of the nerves. The area density of blood vessels was significantly higher in nerves from the Sprague-Dawley rats. The median area density in that strain was 0.0149, while in the Brown Norway rats the median area density was 0.0105.
High-frequency plane waves in the ear canal: Application of a simple asymptotic theory
Authors: Rabbitt R. D.
Published: October 2005

An asymptotic theory describing the propagation of plane waves in a variable cross-section ear canal is combined with pressure measurements in order to determine the energy reflection coefficient at the eardrum and the standing wave patterns along the length of the canal. The relative phase of the reflected wave, and the cross-sectional area function of the ear canal, are also determined from the noninvasive pressure measurements. The theory is based on a high-frequency multiscale solution of the one-dimensional horn equation and is shown to agree well with the phase and amplitude of experimental measurements in human replica ear canals.
A theoretical interpretation of the prevalence rate of noise-induced annoyance in residential populations
Authors: Fidell Sanford , Schultz Theodore , Green David M.
Published: October 2005

A simple statistical model containing only one free parameter is proposed to account for the variability observed in a dosage–effect relationship between an integrated metric of noise exposure and the prevalence of annoyance in a community as synthesized by Schultz [J. Acoust. Soc. Am. 64, 377–405 (1978)]. The model assumes that a community’s noise dose is produced by long-term noise exposure acting through a compressive transformation of the day–night average sound level (DNL). Individual reactions to this noise dose are characterized by a random variable. Individuals are assumed to report a consequential degree of annoyance when the value of this random variable exceeds a criterion level that is not a function of acoustic factors.
Multiple-scattering analysis for a target in an oceanic waveguide
Authors: Hackman Roger H. , Sammelmann Gary S.
Published: October 2005

A multiple-scattering approach is developed for the acoustic scattering from a target in a range-independent oceanic waveguide. The multiple-scattering series is explicitly summed and a solution is obtained in closed form. The final result is algebraically much simpler than that obtained in earlier work, and the individual terms may be straightforwardly interpreted in terms of scattering events in the waveguide. The formalism is applied to the scattering from a target (1) near a sound-soft boundary, and (2) in a waveguide with a single, homogeneous fluid layer over a homogeneous, fluid half-space. Numerical examples are given that illustrate the importance of contributions involving rescattering among the target and the waveguide boundaries.
Green’s functions in an infinite transversely isotropic saturated poroelastic medium
Authors: Kazi-Aoual Mohammed N. , Bonnet Guy , Jouanna Paul
Published: October 2005

The purpose of this article is to study Green’s functions for an infinite transversely isotropic saturated poroelastic medium. In the first part, equations of motions of such a medium are recalled according to Biot’s theory and completed by homogenization techniques, for harmonic displacements. The second part gives Green’s functions for such an infinite medium in the 3-D Fourier-transformed geometrical space. In the third part, a 1-D inverse analytical Fourier transformation, followed by an inverse Hankel transformation, leads to an analytical expression of Green’s functions for harmonic motions. Some numerical methods to compute final Green’s functions in time space are listed.
Conical bores. Part I: Reflection functions associated with discontinuities
Authors: Martínez J. , Agulló J.
Published: October 2005

Reflection functions associated with discontinuities in conical bores are worked out for the usual cases found in woodwind instruments: taper and diameter discontinuities, open and closed ends, and open and closed holes. Radiation at open ends is considered through the impedance formulation for the open end of a cylindrical tube fitted with an infinite flange. The input impulse response of woodwinds, or related functions such as the plane-wave or spherical-wave reflection functions, can be calculated in the time domain by means of these reflection functions through multiple convolutions as shown in the companion article ‘‘Conical bores. Part II: Multiconvolution’’ [Martínez et al., J. Acoust. Soc. Am. 84, 1620–1627 (1988)].
Conical bores. Part II: Multiconvolution
Authors: Martínez J. , Agulló J. , Cardona S.
Published: October 2005

The input impulse response, or related functions such as the plane-wave or spherical-wave reflection functions, of a conical bore with discontinuities can be calculated from the reflection functions associated with discontinuities by means of a multiconvolution process. This approach, as alternative to the Fourier transform of the acoustical impedance Z(f), is attractive because of the detailed description it gives of the pressure time evolution inside the bore. However, the calculation may become rather involved if each reflected and transmitted wave is followed individually, and numerical instability may arise whenever the implied reflection functions contain growing exponentials. The first difficulty has been overcome by summing up all outward traveling waves and all inward traveling waves to give a unique outward wave and a unique inward wave. Numerical instability has been avoided by using an iterative convolution algorithm. Internal damping due to viscous and thermal losses has been located at discontinuities and represented by means of damping functions through convolution products. The reflection functions used are presented in the companion article ‘‘Conical bores. Part I: Reflection functions associated with discontinuities’’ [Martínez and Agulló, J. Acoust. Soc. Am. 84, 1613–1619 (1988)].
Illusory continuity of interrupted speech: Speech rate determines durational limits
Authors: Bashford James A. , Meyers Mark D. , Brubaker Bradley S. , Warren Richard M.
Published: October 2005

Deleted segments of speech can be restored perceptually if they are replaced by a louder noise. An earlier study of this ‘‘phonemic restoration effect’’ found that, when recorded discourse was interrupted periodically by noise, the durational limit for illusory continuity corresponded to the average word duration. The present study employed a different passage of discourse recorded by a different speaker. Durational limits for apparent continuity of discourse interrupted by noise were measured at the normal (original) playback speed, as well as at rates that were 15% greater and 15% less. At the normal playback rate, once again the limit of continuity approximated the average word duration—but of especial interest was the finding that changes in playback rate produced proportional changes in continuity limits. These results, together with other evidence, suggest that phonemic restorations represent a special linguistic application of a general auditory mechanism (auditory induction) producing appropriate syntheses of obliterated sounds, and that for discourse the limits of illusory continuity correspond to a fixed amount of verbal information, and not a fixed temporal value.
Comodulation masking release: Evidence for multiple cues
Authors: Hall Joseph W. , Grose John H.
Published: October 2005

Signal detection was determined in conditions where the masker was a 10-Hz-wide noise band centered on the signal, and in conditions where either a comodulated or noncomodulated noise band (centered at 0.8 times the signal frequency) was also present. Signal frequencies of 500 or 2000 Hz were investigated. In one condition of the first experiment, the signal was exactly the same 10-Hz-wide noise band as the masker, added to the masker in phase. This condition was designed to limit the availability of cues based upon dip listening, suppression, beating, or across-frequency differences in noise envelope correlation, but to afford a cue based upon across-frequency envelope amplitude difference. The narrow-band noise signal resulted in approximately the same magnitude of comodulated masking release (CMR) as was found for a pure-tone signal. This result suggested that one important cue for CMR is an across-frequency difference in envelope amplitude. Stimulus conditions in the second experiment were intended to disrupt cues of across-frequency envelope amplitude difference, but to afford cues based upon across-frequency differences in noise envelope correlation. In this experiment, cues based upon envelope amplitude were impoverished by randomly varying the level of the flanking band from interval to interval, and by adjusting the level in the on-signal band to be the same in the nonsignal intervals as the level of noise plus signal in the signal interval. Again, substantial CMRs occurred, suggesting that another cue for CMR may be envelope pattern or correlation. The results of these experiments indicated that CMR is probably based upon more than one stimulus variable.
Delay-Doppler resolution performance of large time-bandwidth-product linear FM signals in a multipath ocean environment
Authors: Hermand Jean-Pierre , Roderick William I.
Published: October 2005

Active sonar systems that transmit large time-bandwidth (TW)-product linear frequency modulated (LFM) waveforms and receive echoes from targets of unknown range and speed can suffer considerable correlation losses that cannot be predicted from conventional (narrow-band) ambiguity function theory. As is well known, the theory can be modified to include the effects of Doppler distortion on large TW-product signals by correlating the received signal against a reference that is a time-compressed version of the transmitted signal. In this article, the effects of multipath (or target highlight structure) and Doppler on the correlation process for rectangular-weighted large TW-product LFM waveforms are examined. Gaussian-weighted waveforms are also considered to examine sidelobe behavior. It is shown that in a multipath environment, the correlator output peak does not generally occur at the correct Doppler reference channel. This is due to the constructive/destructive interference of the summation of complex delay-Doppler autocorrelation functions associated with each return. A summation technique that identifies the appropriate Doppler reference channel is proposed; this technique allows the target parameters to be estimated if the signal-to-noise ratio is sufficiently high.
Effect of traffic noise on the cyclical nature of sleep
Authors: Thiessen G. J.
Published: October 2005

Sleep changes from shallow to deep and back again in a cyclical manner with a period of around 90 min. The sleep of 12 subjects, each sleeping for 24 nights, was monitored by EEG. The results indicate that the cyclical nature may be somewhat disturbed by continuous free-flowing traffic noise, at a level of 60 dB, if, for instance, waking is always considered as the end of one cycle. However, if a cycle is judged from a bird’s-eye view of the sleep record, then it appears that the average subject persists in his normal cycle and the effect of noise is negligible. But individual differences are great and may even be in opposite directions [G. J. Thiessen and A. C. Lapointe, J. Acoust. Soc. Am. 64, 1078–1080 (1978)], which may result in obscuring real effects when data are averaged over a number of individuals. Defining a ‘‘sleep cycle’’ is of importance in view of reports [M. Herbert and R. T. Wilkinson, Proc. of Congress on Biological Effects on Noise, Dubrovnik, Yugoslavia (1973)] that the disturbance of the sleep rhythm has an effect on performance during the following day.
Elastic constant determination using generation by pulsed lasers
Authors: Bresse L. F. , Hutchins D. A. , Lundgren K.
Published: October 2005

Illumination of a specimen by a pulsed focused laser is known to induce elastic waves, and models are available for both cases of thermoelastic generation and liquid evaporation. In this article, the inverse problem of recovering the elastic constants of a specimen from experimental waveforms recorded on- and off-epicenter is considered. An algorithm, based on nonlinear least-squares fitting, is presented and has been used on experimental displacement signals recorded on an aluminum plate with a Michelson interferometer. The choice of the receiver position is discussed and experimental results are given.
Wave propagation in isotropic linear viscoelastic media
Authors: Strifors Hans C. , Gaunaurd Guillermo C.
Published: October 2005

Assuming isothermal conditions, a suitable form of the free energy is formulated for general, isotropic linear viscoelastic media. On applying a proper form of the principle of dissipation, a strong condition of dissipation is derived, which imposes restrictions on constitutive parameters of particular materials. The field equations of boundary value problems in the time domain and the frequency domain are formulated and, in particular, the problem of scattering of an acoustic pulse with plane or spherical wave front by a viscoelastic scatterer is discussed. The relation to the corresponding elastic scattering problem for steady, harmonic waves is established, and a general scheme of solution for viscoelastic scatterers is laid down.
Scattering from small three-dimensional irregularities in the ocean floor
Authors: Wetton Brian T. R. , Fawcett John A.
Published: October 2005

A perturbation expansion is used in this article to investigate the scattering of acoustic energy from small three-dimensional irregularities of the ocean floor. The concept of modal conversion is stressed. The ocean floor is taken to be the interface between the ocean fluid and a fast fluid bottom. Simple formulas for the modal conversion coefficients are given in terms of the two-dimensional Fourier transform of the irregularity height function.
The sound generated by propagating cracks in sea ice
Authors: Farmer David M. , Xie Yunbo
Published: October 2005

Observations of the sound generated by ice cracking events in the Amundsen Gulf provide an opportunity for studying the mechanisms of the generation and propagation of acoustic signals beneath the Arctic ice cover. Contributions from waves traveling in the ice (longitudinal waves) are identified and shown to be small compared to the direct acoustic wave. Both high-frequency (∼5 kHz) and base-band (200–300 Hz) components occur and are interpreted in terms of a moving source model modulated by the ‘‘slip-stick’’ process considered in earthquake mechanics. It is shown that the high- and low-frequency components can be related to the vertical and horizontal length scales of the crack.
The interpretation and evaluation of a 3-MHz acoustic backscatter device for measuring benthic boundary layer sediment dynamics
Authors: Libicki Charles , Bedford Keith W. , Lynch James F.
Published: October 2005

For ultrasonic backscatter devices to be of aid in studies of turbulent sediment transport dynamics, the procedures for converting signal to concentration estimates should be as accurate as possible, and the space and time resolution should be as high as possible. Signal conversion for the 3-MHz system considered here takes into account nearfield beam pattern effects on propagation and attenuation. Enhancing resolution involves explicit consideration of various sources of noise and interference. The results of field deployments demonstrate that, with signal conditioning and ensemble averaging, signal-to-noise ratios can be achieved that allow turbulent variation in concentration to be measured. Two possible sources of error in the conversion procedure are: (1) attenuation due to scatters is not measured in situ, but must be estimated from the data, and (2) with a single-frequency beam, the effects on scattering response of concentration variation and particle-size variation cannot be uncoupled.
The calculation-frequency method for fast parabolic-equation modeling at high frequencies
Authors: Moore-Head M. E. , Jobst W. , Showalter J. A.
Published: October 2005

This article describes a method for efficient parabolic-equation modeling in the kilohertz frequency range. Computer use may be reduced to less than 1% of that expected with current standard methods by using a reduced calculation frequency but compressional-wave attenuation and boundary losses appropriate to the prediction frequency. Restrictions are discussed. Modeled and measured transmission loss are compared.
Propagating, damped, and leaky surface waves on the corrugated traction-free boundary of an elastic half-space
Authors: Boström Anders
Published: October 2005

The dispersion relation for surface waves on the corrugated boundary (periodic in one direction and constant in the other) of an elastic half-space is derived using a modal approach, and the result is shown to be equivalent to that derived by the null-field approach. The dispersion relation is solved numerically for roots on all Riemann sheets for varying corrugation heights, frequencies, and angles of propagation. Many of the roots move on several sheets, and this leads to zero, one, or two roots residing on the physical sheet.
Production of pico and subpicosecond optoacoustic pulses
Authors: Dharamsi A. N. , Hassam A. B.
Published: October 2005

A method for generating pico- and subpicosecond optoacoustic pulses is discussed. The physical mechanism is based upon the phenomenon of ‘‘electronic expansion’’ (or photostriction) in which the lattice constant of a solid changes upon the creation of electron–hole pairs. Acoustic signals generated by this mechanism would be up to an order of magnitude shorter than those generated by other schemes currently in use. An expression for the acoustic compression expected in this method is derived. It is shown that the nonthermal nature of the phenomenon, in conjunction with the band structure of materials exhibiting gaps between conduction bands, can be exploited to obtain ultrashort optoacoustic pulses that have no thermoelastic components. A comparison of the thermoelastic and nonthermal photostrictive mechanisms is made.
An image reconstruction algorithm using phase conjugation for diffraction-limited imaging in an inhomogeneous medium
Authors: Ikeda Osamu
Published: October 2005

A diffraction-limited imaging method in an inhomogeneous medium, which uses phase conjugation and multiple reflectors, is proposed. First, several reflectors with frequency-dependent reflectivities are put in the observation area. Second, ultrasonic signals are acquired for all combinations of transmitter-receiver elements of the array, and data acquisition is repeated for each of the frequencies. Then, signal processing is performed in a computer: (1) The reflected wave in the mth step is phase conjugated and transmitted to get the reflected wave in the (m+1)th step until convergence is attained; (2) the converged phase-conjugated wave is scanned in bearing to get an image; and (3) good image parts obtained for several frequencies are joined together to extend the good image area.
Velocity and absorption of ultrasound in binary solutions of polyvinylpyrrolidone and water
Authors: Spickler P. , Abdel-Raziq I. , Yun S. , Stumpf F. B.
Published: October 2005

Ultrasonic velocity and absorption and shear viscosity measurements were made as a function of concentration and temperature for binary aqueous solutions of the polymer polyvinylpyrrolidone. The polymer has a molecular weight of 360 000 and was mixed with water in several concentrations ranging from 0% to 9% by weight. The frequency used was 21 MHz and the temperature range was 20 °C to 45 °C. The velocity shows a nonlinear increase with temperature and a nearly linear increase with concentration. The α/f 2 and viscosity values increase monotonically with concentration, and these values decrease with temperature. The temperature behavior, in a general sense, for the velocity and α/f 2 of the solution is similar to that of pure water. As the concentration increases from 0% to 9%, the viscosity increases by more than two orders of magnitude, while the α/f 2 value increases by less than one order of magnitude. No strong evidence of a critical concentration was observed.
Effect of monomolecular films on the underlying ocean ambient-noise field
Authors: Rohr Jim , Glass Ray , Castile Brett
Published: October 2005

A series of at-sea tests has unequivocally established that the presence of a monomolecular film on the sea surface results in a pronounced reduction of ambient noise beneath the film. This reduction was observed to begin around 2 kHz, continue to at least 20 kHz, and was evident to some degree throughout sea states 1 1/2 to 6. A predictive model is developed that is generally consistent with the film’s observed behavior, and several possible mechanisms are speculated through which the film could affect the underlying ambient-noise field.
Calculation of free-field deviation in an anechoic room
Authors: Wang Ji-qing , Cai Biao
Published: October 2005

After a review of various calculation methods currently available for free-field deviation (in dB) in an anechoic room, a more precise and rational calculation of the sound field is presented in this article by solving wave equations including the interference of first reflections only. In the case of a pure tone, the phase factor plays an important role in the calculation; therefore, the calculated free-field deviation (in dB) also depends on the source position, measuring direction and distance from the source, and the frequency used in the test in addition to other factors such as the dimensions of the room and sound absorption characteristics of all of the boundary surfaces. For a broadband noise, calculation becomes simpler as the phase factor can be ignored, and a general equation of such a calculation is given for any source position and different combinations of boundary absorption. The results of the calculation can be shown in a diagram with the aid of a microcomputer, as a map of free-field range within a given maximum deviation. This is very useful as a guideline to design and to use an anechoic room.
Application of an intelligent signal processing system to acoustic emission analysis
Authors: Grabec Igor , Sachse Wolfgang
Published: October 2005

This article describes a novel approach for analyzing elastic wave signals to obtain a solution to simple inverse source problems. By using a simulated intelligent system that resembles the structure of a neural network and an acoustic source with its associated field of elastic waves in a plate, a set of pattern vectors is generated. The memory of the system is formed through a learning process in which a systematic series of experiments is presented to the system. In the experiments described here, the system was trained using simulated acoustic emission signals generated by a normal force acting on a thick plate to which information about the source related to its location and characteristics was appended. It is demonstrated, using such a trained system, that one can recover the characteristics of an unknown source from the acoustic signals emitted by it. It is also shown that one can synthesize from the memory the acoustic signals corresponding to an arbitrary source without using any elastodynamic theory.
Perceptual grouping of formants with static and dynamic differences in fundamental frequency
Authors: Gardner R. B. , Gaskill Sally A. , Darwin C. J.
Published: October 2005

The perceptual consequences of exciting one formant (F2 or F4) of a composite syllable with a different fundamental from the others were examined in experiment 1 using a four-formant syllable for which F1, F2, and F3 give /ru/ and F1, F3, and F4 give /li/. When all four formants are on the same fundamental, the percept is /ru/, but exciting F2 on a sufficiently different fundamental gave predominantly /li/ percepts. Smaller differences in fundamental left the phonetic percept unchanged but made F2 stand out as a separate sound source. Exciting F4 on a different fundamental also made it stand out as a separate sound source, though larger differences in fundamental were needed than for F2. Experiment 2 replicated these static effects of fundamental frequency differences on F2, but failed to find any substantial effect of coherent or incoherent fundamental frequency modulation functions on perceptual grouping or separation. Although static differences in fundamental frequency exert a strong effect on the perceptual grouping of formants both in terms of the number of sound sources heard and the perceived phonetic category, the coherence of fundamental frequency movement has almost no independent effect on the perceptual grouping of formants.
Diffraction of a plane acoustic wave by four equal circular infinite soft strips
Authors: Sharma K. A. , Jain D. L.
Published: October 2005

This article deals with the solution of the problem of diffraction of a time-harmonic obliquely incident plane acoustic wave by four equal infinite coaxial soft circular strips. A simple integral equation technique is presented to solve this two-dimensional problem by the perturbation method when the wavelength of the incident plane wave is much larger than the radius of the circular strips. Approximate expressions for the farfield amplitude and the scattering cross section are derived.
Fundamental frequency modulation of the human voice by the heartbeat: Preliminary results and possible mechanisms
Authors: Orlikoff Robert F. , Baken R. J.
Published: October 2005

Signal-averaging techniques reveal that the vocal fundamental frequency (F0) of a sustained vowel is modulated over a period equal to that of the speaker’s heart cycle. Average F0 deviation varies in an orderly way from about 0.5% to about 1.0% as F0 changes. Location of the peak deviation in the time frame of the heart cycle also changes systematically with vocal F0. Modulation of the vocal F0 is likely to be caused by pressure-related changes in the stiffness of the vascular bed of the vocal folds and by alterations of the geometry of the thyroarytenoid muscle produced by periodic vascular engorgement.
Inhibiting the Lombard effect
Authors: Pick Herbert L. , Siegel Gerald M. , Fox Paul W. , Garber Sharon R. , Kearney Joseph K.
Published: October 2005

The Lombard effect is the tendency to increase one’s vocal intensity in noise. The present study reports three experiments that test the robustness of the Lombard effect when speakers are given instructions and training with visual feedback to help suppress it. The Lombard effect was found to be extremely stable and robust. Instructions alone had little influence on the response to the noise among untrained speakers. When visual feedback correlated with vocal intensity was presented, however, subjects could inhibit the Lombard response. Furthermore, the inhibition remained after the visual feedback was removed. The data are interpreted as indicating that the Lombard response is largely automatic and not ordinarily under volitional control. When subjects do learn to suppress the effect, they seem to do so by changing overall vocal level rather than their specific response to the noise.
Application of the parabolic equation to sound propagation in a refracting atmosphere
Authors: Gilbert Kenneth E. , White Michael J.
Published: October 2005

A wide-angle parabolic equation (PE) model is presented that is applicable to sound propagation in a steady (nonturbulent) atmosphere overlying a flat, locally reacting ground surface. The numerical accuracy of the PE model is shown by comparing PE calculations to calculations from a ‘‘fast-field program’’ (FFP). For upward refraction, the PE and FFP solutions agree to within 1 dB out to ranges where the sound-pressure levels drop below the accuracy limits of both models. For downward refraction, the PE and FFP agree to within 1 dB except at deep interference minima. Parabolic equation calculations are also compared to measured values of excess attenuation for 15 different combinations of frequencies and ranges. In general, the PE model gives good agreement with the average experimental values. For upward refraction at the highest frequency (630 Hz), however, the PE predicts a strong shadow zone that is not observed in the data.
A study of the spectrum of an acoustic field in shallow water due to noise sources at the surface
Authors: Naidu P. S. , Mohan P. G. Krishna
Published: October 2005

An expression for the spectrum and cross spectrum of an acoustic field measured at two vertically separated sensors in shallow water has been obtained for any correlated noise sources distributed over the surface. Numerical results are presented for the case where the noise sources, white noise and wind-induced colored noise, are contained within a circular disk centered over the sensors. The acoustic field is generally inhomogeneous except when the channel is deep. The coherence function becomes real for a large disk, for a radius greater than 25 times the depth of the channel, decreases with further increase of the size of the disk, and finally tapers off after certain limiting size, approximately given by 1/α, where α is the attenuation coefficient.
Sound radiation from finite plates under the action of multiple random point forces
Authors: Peng H. , Keltie R. F.
Published: October 2005

The problem of acoustic radiation from baffled finite elastic plates driven by multiple random point forces is analyzed in this study. Expressions for the surface acoustic intensity and the radiated sound power are derived under the condition of neglecting fluid loading. By assuming the plates to be lightly damped and neglecting the modal coupling effects, approximate solutions for the acoustic intensity and sound power are obtained. An experimental study is carried out to measure the surface acoustic intensity patterns and to compare them with the analytical results. The effects of the temporal and the spatial correlations between the applied point forces on the acoustic intensity patterns and the sound power levels are discussed.
Acoustic levitation and the Boltzmann–Ehrenfest principle
Authors: Putterman S. , Rudnick Joseph , Barmatz M.
Published: October 2005

The Boltzmann–Ehrenfest principle of adiabatic invariance relates the acoustic potential acting on a sample positioned in a single-mode cavity to the shift in resonant frequency caused by the presence of this sample. This general and simple relation applies to samples and cavities of arbitrary shape, dimension, and compressibility. Positioning forces and torques can, therefore, be determined from straightforward measurements of frequency shifts. Applications to the Rayleigh disk phenomenon and levitated cylinders are presented.
An intensity approximation for source motion in shallow water, with application to passive tracking
Authors: Robertson J. S. , Jacobson M. J. , Siegmann W. L.
Published: October 2005

The behavior of incoherent total-field intensity is considered for a moving cw source in shallow water. The ocean channel is assumed isospeed, with a planar perfectly reflecting surface and planar lossy bottom. The source moves on a linear path at constant depth, and the receiver is fixed on the bottom. An expression for incoherent total-field intensity loss is derived in terms of source-motion and environmental parameters. For a bottom with uniform loss per ray reflection, special functions are used to develop and analyze an approximation for intensity. The behavior of this novel approximation with respect to variations in source quantities, such as range, depth, and speed, as well as bottom-loss variations, suggests its possible application in source-motion prediction. Two properties of the approximation, peak curvature and peak width of intensity versus time, are selected as source-motion descriptors. Both are shown to be relatively insensitive to bottom-loss variations, but sensitive to changes in source quantities. Descriptors are applied to an example, and their possible use in supplementing existing passive tracking methods is discussed.
Modeling the perception of concurrent vowels: Vowels with the same fundamental frequency
Authors: Assmann Peter F. , Summerfield Quentin
Published: October 2005

The ability of listeners to identify pairs of simultaneous synthetic vowels has been investigated in the first of a series of studies on the extraction of phonetic information from multiple-talker waveforms. Both members of the vowel pair had the same onset and offset times and a constant fundamental frequency of 100 Hz. Listeners identified both vowels with an accuracy significantly greater than chance. The pattern of correct responses and confusions was similar for vowels generated by (a) cascade formant synthesis and (b) additive harmonic synthesis that replaced each of the lowest three formants with a single pair of harmonics of equal amplitude. In order to choose an appropriate model for describing listeners’ performance, four pattern-matching procedures were evaluated. Each predicted the probability that (i) any individual vowel would be selected as one of the two responses, and (ii) any pair of vowels would be selected. These probabilities were estimated from measures of the similarities of the auditory excitation patterns of the double vowels to those of single-vowel reference patterns. Up to 88% of the variance in individual responses and up to 67% of the variance in pairwise responses could be accounted for by procedures that highlighted spectral peaks and shoulders in the excitation pattern. Procedures that assigned uniform weight to all regions of the excitation pattern gave poorer predictions. These findings support the hypothesis that the auditory system pays particular attention to the frequencies of spectral peaks, and possibly also of shoulders, when identifying vowels. One virtue of this strategy is that the spectral peaks and shoulders can indicate the frequencies of formants when other aspects of spectral shape are obscured by competing sounds.
Interactive factors in consonant confusion patterns
Authors: Bell Theodore S. , Dirks Donald D. , Carterette Edward C.
Published: October 2005

Confusion patterns among English consonants were examined using log-linear modeling techniques to assess the influence of low-pass filtering, shaped noise, presentation level, and consonant position. Ten normal-hearing listeners were presented consonant–vowel (CV) and vowel–consonant (VC) syllables containing the vowel /a/. Stimuli were presented in quiet and in noise, and were either filtered or broadband. The noise was shaped such that the effective signal level in each (1)/(3) octave band was equivalent in quiet and noise listening conditions. Three presentation levels were analyzed corresponding to the overall rms level of the combined speech stimuli. Error patterns were affected significantly by presentation level, filtering, and consonant position as a complex interaction. The effect of filtering was dependent on presentation level and consonant position. The effects stemming from the noise were less pronounced. Specific confusions responsible for these effects were isolated, and an acoustical interaction is suggested, stressing the spectral characteristics of the signals and their modification by presentation level and filtering.
A PVdF membrane resonator as a directional acoustic sensor
Authors: Harper Philip G. , Treherne David M. , Su Daoning
Published: October 2005

A tensioned film of polyvinylidene fluoride (PVdF) mounted on a rim of a metal hemisphere forms a directional acoustic resonator. When the resonator is acoustically excited, a piezoelectric film voltage is developed that shows strong directionality due to the anisotropy of the film. The system response is investigated under a variety of conditions using optical-fiber detection as a check. Some explanatory theory is appended.
Intensity discrimination of pulsed tones by the goldfish (C
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Authors: Fay Richard R.
Published: October 2005

Intensity discrimination thresholds for 500-ms pure-tone bursts were measured as a function of frequency in the goldfish (Carassius auratus) using classical respiratory conditioning. At 55-dB sensation level (SL), thresholds range from 1.44–2.2 dB between 100 and 1600 Hz. There is no important effect of frequency on intensity discrimination. Thresholds at 35-dB SL average 0.7 dB higher than at 55-dB SL. This is a small difference in the context of the threshold variability. In intensity discrimination acuity, the goldfish is quantitatively similar to other vertebrates, including birds and mammals.
The acoustic scattering by a submerged, spherical shell. I: The bifurcation of the dispersion curve for the spherical antisymmetric Lamb wave
Authors: Sammelmann Gary S. , Trivett David H. , Hackman Roger H.
Published: October 2005

The acoustic scattering by thin-walled, evacuated, elastic spherical shells immersed in water is studied. The analytic structure of the scattering amplitude in the complex-k plane is directly analyzed using Cauchy’s residue theorem, and dispersion curves are presented for the lowest elastic modes of the fluid-loaded shell. It is found that fluid loading has a profound effect on the vacuum dynamical characteristics of the shell; the spherical equivalent of the first antisymmetric, flat-plate Lamb wave for the fluid-loaded shell bifurcates into two distinct modes near the frequency that the vacuum dispersion curve transitions from a subsonic to a supersonic phase velocity. By way of contrast, the spherical equivalent of the first symmetric Lamb wave is essentially unaffected. The salient features of the free-field scattering process are also analyzed in terms of the resonance excitation of these modes.
Observation of surface waves on a solid cylinder in a fluid
Authors: Stoyanov Aleksandr J. , Überall H. , Luppé Francine , Quentin G.
Published: October 2005

An experimental study of the scattering of ultrasonic short pulses by aluminum cylinders in water at grazing incidence for values of ka=50–140 is presented. Surface waves with speed ≲c (sound speed in water) are observed, and their dependence on angular distance traveled over the circumference of the cylinder is measured. In addition to presentation of the measurement of the first Franz-type surface wave that had been previously observed [W. G. Neubauer, J. Acoust. Soc. Am. 44, 298 (1968); 45, 1134 (1969); Maze et al., Phys. Lett. 75 A, 214 (1980)], evidence of the ultrasonic excitation of the second Franz wave, and possible evidence of the excitation of the Scholte (or Stoneley) wave, is also shown. Of these, the second Franz wave has never been observed before.
Site dependence of wind-dominated ambient noise in shallow water
Authors: Ingenito F. , Wolf S. N.
Published: October 2005

A survey of ambient noise data taken under wind-dominated conditions in shallow water shows substantial differences in spectrum level (often greater than 10 dB) under the same windspeed and sea-state conditions. This area-dependent effect, which is evident even in long-term averaged data, is caused by differences in ocean bottom properties, water depth, and sound-speed profile. A shallow-water, wind-noise model is used to remove propagation effects from selected data sets that cover a broad range of bottom types, water depths, and sound-speed profiles. These reduced data exhibit less variability, and it is concluded that the model is capable of predicting the effect of the shallow-water environment on the spectrum level of wind-dominated ambient noise. The results also suggest that commonly used universal ambient noise curves that do not take into account environmental differences are inferior to the model predictions in shallow water.
Modal beamforming array gain
Authors: Yang T. C.
Published: October 2005

In a previous article [T. C. Yang, J. Acoust. Soc. Am. 82, 1736–1745 (1987)], range and depth were successfully estimated by modal beamforming. In this article, the modal beamforming array gain is derived in closed form for a vertical array of N hydrophones. For the case of white noise and a long well-populated vertical array, the array gain nearly equals 10 log N. For the case of colored noise and a finite aperture, finite element vertical array, the array gain degrades from the theoretical by an amount determined by the mode depth amplitudes evaluated at the source and receiver depths and the modal covariance matrix of the noise. Numerical estimates of array gain are given for the FRAM IV vertical array for a colored noise environment in the Arctic sound channel. Approximately 1-dB array gain degradation at 47 Hz is found. Proper array configuration and deployment depth are not only important for optimizing array gain but also critical for maximizing the input signal-to-noise ratio on a vertical array, which together with the array gain determine the array output signal-to-noise ratio.
Transmission of a sound beam across a two-fluid interface: Numerical results and asymptotic expressions
Authors: Tjo/tta Jacqueline Naze , Sagen Hanne , Tjo/tta Sigve
Published: October 2005

The transmission of a real sound beam at the interface between two homogeneous and dissipative fluid layers is considered. Numerical results are obtained using a fast Fourier transform algorithm. The results show that, at a given incident angle, the direction and displacement of the beam critically depend on the absorption coefficient and on the distance between the source and the interface. Various asymptotic formulas are also presented, which allow for a physical interpretation of the numerical results.