bluuebunny/crossref_metadata_2025_split huggingface dataset:
Audotory intensity discrimination with bursts of reproducible noise
Authors: Raab David H. , Goldberg Israel A. 
Published: October 2005

Auditory−intensity discrimination was investigated using gated bursts of reproducible noise. Weber fractions were determined at a number of energy levels with stimuli that differed in intensity, duration, and bandwidth. Weber’s law was approximated in all cases. In addition, discriminability was found to be somewhat dependent on burst duration and relatively independent of noise bandwidth; threshold signal−to−noise ratios improved when duration was increased from 10 to 100 msec, but not when bandwidth was increased from 500 to 5000 Hz. The data were compared with the results of a second experiment in which the stimuli were random—rather than pseudorandom—noises. Finally, the results of both experiments were compared with predictions about intensity discrimination derived from two theoretical models: (1) a Poisson−counting mechanism and (2) an energy detector incorporating additive internal noise.
Subject Classification: 65.35, 65.58.
Control of pharyngeal cavity size for English voiced and voiceless stops
Authors: Bell−Berti Fredericka 
Published: October 2005

This study reports on pharyngeal cavity size change mechanisms associated with voiced−voiceless stop contrast in English. Electromyographic recordings were obtained from pharyngeal and infrahyoid muscles of three speakers, using bipolar, hooked−wire electrodes. The EMG potentials were sampled and averaged under computer control. The utterances sampled were 27 pairs of nonsense disyllables that contrasted only in the voicing of one stop consonant. All the English stop cognate pairs were included. Two modes of expanding the pharynx for voiced stops are proposed, each applying to a different group of muscles; an ’’active’’ mode, requiring increased muscle activity to expand the pharynx; and a ’’passive’’ mode, requiring suppression of muscle activity to expand the pharynx. The data reveal different patterns of use of the two expansion modes for the three subjects. The results are discussed in terms of current phonological theory.
Subject Classification: 70.20.
Considerations for the detection of acoustic emission waves in thin plates
Authors: Egle D. M. , Brown A. E. 
Published: October 2005

A series of simulated acoustic emission experiments in thin plates and bars conducted to assess the effects of structural geometry on the detection of emission is described. It is shown that the structure introduces peaks in the received signal spectra corresponding to thickness resonances that may be estimated from Lamb wave theory. Spectra of acoustic emission signals from a thin−walled pressure vessel show a peak at the frequency corresponding to the lowest symmetric plate mode. It is concluded that a significant portion of the energy detected by a surface contact transducer on a thin−walled structure is concentrated at these resonances and should be accounted for in choosing a detection system.
Subject Classification: 35.10, 35.80.
Model for ultrasonic field analysis in solids
Authors: Rose Joseph L. , Meyer Paul A. 
Published: October 2005

In this paper a theoretical model is presented that can be used to evaluate analytically ultrasonic transducer longitudinal wave−generation characteristics in homogeneous isotropic solids. Comparisons with fluid−type solutions are also outlined. A continuous wave solution is determined first, from which particle displacement, particle velocity, and stress solutions for arbitrary pulse shapes are obtained. The ultrasonic field distributions resulting from several basic pulse shapes are presented along with the results of an experimentally obtained distribution. Nearfield and beam angle of divergence for pulse output transducers are also discussed. In addition to developing data for ultrasonic field analysis in solids, the equations developed can be used for obtaining solutions to many other ultrasonics problems. For example, it now becomes possible to develop equations that can analyze the resulting stress and particle velocity distribution in a multilayer structure for materials subjected to either normal beam incidence or angle beam incidence. The work may also be extended to include many aspects of ultrasonic field measurement analysis for flaw characterization work.
Subject Classification: 35.65; 20.50.
Acoustic emission: some applications of Lamb’s problem
Authors: Breckenridge Franklin R. , Tschiegg Carl E. , Greenspan Martin 
Published: October 2005

A method for obtaining the signatures (waveforms) of certain acoustic emission events has been developed. The waveform is that at the source, free of contamination by ringing of the specimen, apparatus, and transducer. The technique is based on the comparison of two signals at the transducer, one from the event in question and one from an artificial event of known waveform. The apparatus is also adapted to the calibration of transducers in a certain sense. The configurations of source (real or simulated acoustic−emission event) and receiving transducer correspond to those of some special cases of Lamb’s problem. As a byproduct, the results may be of some interest to seismologists.
Subject Classification: 40.42; 35.54, 35.80, 35.68; 40.50; 85.44.
Parametric array in air
Authors: Bennett Mary Beth , Blackstock David T. 
Published: October 2005

An experimental investigation of the parametric array in air was conducted using a circular piston transducer which produced spherically spreading, collinear, primary beams at frequencies of 18.6 and 23.6 kHz. Since source levels were not strong (about 110 dB re 0.0002 μbar at 1 ft), the 5−kHz difference frequency signal generated by the parametric array was relatively weak. Because of space limitations, all measurements were made in the nearfield of the array. Spurious difference frequency signals resulting from intermodulation distortion in the receiving system were suppressed by judicious choice of electronic components and by the addition of an acoustical filter in front of the microphone. The classic properties of the parametric array were observed. The 5−kHz beam was narrow, and no minor lobes were evident. The propagation curve first increased with increasing range, reached a broad maximum, and then gradually decreased. Theoretical predictions were based on a perturbation solution of Burgers’ equation and on the integral solution of the inhomogeneous wave equation. Comparison of measured results with these predictions conclusively demonstrated the existence of the parametric array in air. Beam patterns and propagation data obtained for the second−harmonic and sum−frequency signals also confirmed theoretical predictions.
Subject Classification: 25.35.
Measurement of the sound speed in bottom layers
Authors: Stickler D. C. 
Published: October 2005

In many applications of underwater acoustics, the ocean bottom is adequately characterized by a critical angle and a density. An estimate of the sound speed in the bottom is obtained by seismic refraction measurements (i.e., measurements of arrival time) or bottom−reflection measurements. In this paper, the theoretical basis is presented for an alternate technique that, it is hoped, will simplify the determination of the critical angle(s) associated with high−speed bottom layers. The technique requires the measurement of the normal component of the specific acoustic impedance at the ocean−bottom interface. As a function of incidence angle, this impedance function displays a strong peak near the critical angle. The precise location depends in a predictable manner on the location of the source, the source frequency, and the sound speed in the bottom. This technique exploits this dependence to obtain an estimate of the sound speed in the bottom.
Subject Classification: 30.25, 30.20.
Vibration of simply supported rectangular and square plates to which lumped masses and dynamic vibration absorbers are attached
Authors: Snowdon J. C. 
Published: October 2005

The forced vibration of internally damped rectangular and square plates with simply supported boundaries is described theoretically. Calculations that illustrate the frequency dependence of the force transmissibility and driving−point impedance of the plates are presented. Both central and noncentral driving forces are considered, and the reduction in plate vibration that results from the attachment of central loading masses and dynamic vibration absorbers is demonstrated. The way in which the natural frequencies of the plates are moved to progressively lower frequencies as the loading mass is increased is explained and illustrated. Conditions of optimum tuning and damping for the dynamic absorbers are described and design data are tabulated. The resilient mounting of massive vibrating items on the plates is also considered. The vibrating items are supported via four damped springs that are symmetrically, but otherwise arbitrarily, located with respect to the plate centers. Advantageous reductions in force transmissibility are shown to result from judicious choice of spring locations that enable the excitation of several modes of plate vibration to be avoided.
Subject Classification: 40.24, 40.70.
Flexural and extensional vibrations of simply supported laminated rectangular plates
Authors: Thomas Charles R. 
Published: October 2005

The author has previously derived an effective stiffness, velocity−corrected theory of laminated composite plates based upon a microstructure plate theory developed by C. T. Sun. This theory is now used to study the flexural and extensional vibrations of simply supported rectangular plates; comparisons will be made to similar results obtained from a reduced effective modulus or transversely isotropic plate theory. Free vibration frequency equations for simply supported edges are developed by passing solutions harmonic in both length and width through the differential equations while at the same time automatically satisfying the boundary conditions for simple supports. The variation of dimensionless frequency for such dimensionless variables is discussed and comparisons of the effective stiffness and effective modulus frequency results are made.
Subject Classification: 40.24.
Analysis of intermodulation in thickness−shear and trapped energy resonators
Authors: Tiersten H. F. 
Published: October 2005

Electroelastic equations containing terms up to cubic in the small mechanical displacement field, but no higher than linear in the electric variables, are applied in the analysis of intermodulation in rotated Y−cut quartz oscillators. Both pure thickness−shear vibrators and essentially thickness−shear trapped energy resonators are treated. In the linear part of the analysis of the trapped energy resonator, a closed−form asymptotic expression for the frequency wavenumber dispersion relation for the fundamental and odd overtone thickness−shear branches near cutoff is obtained from the three−dimensional linear equations. Lumped parameter representations of the solutions, which are valid in the vicinity of a resonance, are presented for the linear and nonlinear portions of both the pure thickness−shear and trapped energy thickness−shear problems. The influence of the driving and detecting circuitry is included and, in particular, in each case the relation between the intermodulation and driving voltage is obtained. Application of this relation to a number of AT−cut quartz fundamental and third overtone trapped energy resonators yields good agreement with experiment and an estimate of the fourth−order elastic constant cE46666 for the AT−cut.
Subject Classification: 40.24, 40.20, 40.65; 85.32.
One− and two−frequency stimulation of tactile receptors: test of a model
Authors: Lopater Sanford , Hahn J. F. 
Published: October 2005

Sinusoidal mechanical stimulation of Type I or Type II tactile single units in cat with single frequencies or with two mixed frequencies typically yields rate−intensity functions that include irregularities called ’’plateaus’’ and ’’dips.’’ These functions are predicted by a simple model of exponential sensitivity recovery after the occurrence of each impulse. This requires determination of only a resting threshold and a time constant for the unit.
Subject Classification: 65.70, 65.28.
Nonlinear distortion of ultrasonic waves in solids: approach of a stable backward sawtooth
Authors: Bains James A. , Breazeale M. A. 
Published: October 2005

A large−amplitude pulsed ultrasonic wave at 30 MHz in fused silica is shown to generate second harmonics out of phase with those generated by the same ultrasonic wave in copper. This phase difference, interpreted as evidence of the approach of a backward sawtooth in fused silica, results from the fact that C111 is positive. In copper C111 is negative.
Subject Classification: 25.15, 25.20; 35.26.
Preliminary experiment to measure periodicities of large-scale ocean movements with acoustical signals
Authors: LaCasce E. O. , Beckerle J. C. 
Published: October 2005

The acoustic signals received from explosive charges, fired at 1200-m depth and range of about 370 km from a hydrophone at 1200 m along three bearings only 10 ° apart, showed measurable differences for each bearing, although the thermocline sound-speed conditions were only slightly different. Since large-scale (300–500 km) internal baroclinic waves that propagate slowly westward in the ocean (period 50–200 days) perturb the thermocline to a much greater extent, a proposal to monitor with acoustic signals the period of thermocline oscillations caused by these waves is feasible.
Subject Classification: 30.20.
Comments on ’’Eigenfrequencies of thin plates and layer potentials’’ [J. Vivoli and P. Filippi, J. Acoust. Soc. Am. 55, 562–567 (1974)]
Authors: Laura P. A. A. 
Published: October 2005

It is suggested that, to a certain extent, the difference between theoretical and experimental values of the eigenfrequencies may be due to in-plane compressive stresses induced by the clamping device.
Subject Classification: 40.24.
Comments on (1) ’’Negative resistance mode of forced oscillations of a string,’’ [G. V. Anand, J. Acoust. Soc. Am. 54, 692–698 (1973)], (2) ’’Nonlinear resonance in stretched strings with viscous damping,’’ [G. V. Anand, J. Acoust. Soc. Am. 40, 1517–1528 (1966)]
Authors: Niranjan Parvathy 
Published: October 2005

This letter points out certain errors in the mathematical formulations and physical interpretations in the above two articles.
Subject Classification: 40.22, 40.30.
Spherical averaging in a diffuse sound field
Authors: Chien Chi-Shing , Waterhouse Richard , Lubman David 
Published: October 2005

In earlier work [Lubman et al., J. Acoust. Soc. Am. 53 650–659 (1973)], the effectiveness of continuous averaging over a surface in a diffuse sound field was compared with that of averaging the field values at discrete points. Here the comparison is extended to the case of continuous averaging over the surface and volume of a sphere. Formulas for the variance are obtained which show that the oversampling of correlated values increases the variance and yields a poorer average.
Subject Classification: 45.30; 50.25; 55.65; 60.20.
On the phase sensitivity of neurons of the cat’s auditory system
Authors: Kotelenko L. M. , Radionova E. A. 
Published: October 2005

It is established that neurons from the cochlear nucleus and inferior colliculus in a great majority of cases show a pronounced reaction to the phase shift of one of the components in a two-tone complex signal. Diminution or augmentation of both the phasic and tonic discharge patterns may take place with the phase shift. The interrelation between frequencies and intensities of the components forming the complex signal are of importance for phase effects. There is a certain connection between the phase sensitivity of a neuron and inhibitory phenomena in its activity. The response area, on the contrary, seems to show no correlation with the neuron phase sensitivity.
Subject Classification: 65.44, 65.60.
Wave mechanics of boundary layer turbulence and noise
Authors: Landahl Marten T. 
Published: October 2005

Recent advances in the understanding of the structure of boundary layer turbulence form the basis of a new conceptual model for the fluctuating velocity field. In this, an ’’active’’ mode of small-scale motion is coupled to a large-scale ’’passive’’ mode by aid of wave mechanical considerations. The small-scale motion originates during the intermittent ’’bursting’’ in the wall layer, leading to excitation of large-scale, damped, traveling shear waves. It is argued that the passive-wave-like mode gives the major contribution to the pseudosound, whereas the active bursting mode serves as the predominant source for the radiative noise. It is shown that the bursting mode gives rise to compact noise sources of both dipole and quadrupole type whose strengths are related to the turbulent shear stress production.
Subject Classification: 28.65; 50.55.
Study of acoustical fluctuations and ocean movements over one deep-ocean skip distance
Authors: Beckerle John C. , Broek Howard W. , LaCasce E. O. 
Published: October 2005

This experiment studies the relationship between ocean movements and acoustical fluctuations southwest of Bermuda. Sound transmission over a single skip distance RSR path was maintained for a 33-h period. During the same time interval, ocean changes were monitored both at the source and near the second turning point of the sound-ray path. Some correlations were observed among some of these observations.
Subject Classification: 30.20; 28.60.
Helmholtz equation as an initial value problem with application to acoustic propagation
Authors: Fitzgerald R. M. 
Published: October 2005

The parabolic equation method for the solution of the elliptic Helmholtz equation in a waveguide is analyzed in terms of normal modes and is found to involve two approximations. The approximate treatment of mode coupling becomes exact in the limit of negligible scattering into the backward hemisphere. The approximate treatment of mode propagation becomes exact in the limit of uncoupled, single-mode propagation. An estimate of the maximum range over which multimode propagation is accurately predicted is derived and a procedure is indicated whereby this maximum range can be increased. The result is a method, based on the parabolic equation approximation, whereby the Helmholtz equation can be solved as an initial value problem. The solution obtained approaches the exact solution in the limit of negligible backscatter. Application is considered to the problem of acoustic propagation in an ocean medium having range- and depth-dependent properties.
Subject Classification: 30.20.
Perturbation method for determining acoustic rays in a two-dimensional sound-speed medium
Authors: Jacobson M. J. , Siegmann W. L. , Weinberg N. L. , Clark J. G. 
Published: October 2005

Sound speed is assumed to be a function of one horizontal coordinate and depth, and the medium is taken to be time independent during a sound transmission. Rays are assumed to lie in a vertical plane and a differential equation is given for their solution. A perturbation technique is presented for determining the rays, and is applied when the horizontal sound-speed variation is slow and much less than the vertical variation. Under appropriate assumptions, ray arcs above the SOFAR axis are found to be approximately elliptical, and a modified Snell’s law is given. The sound speed is taken to be bilinear with depth, with the upper portion pivoting with range, thereby approximating the effect of a single-frequency internal wave. Numerical examples of SOFAR ray geometry are presented and interpreted for various internal-wave phase angles and wavelengths. The sound speed near the source has a major effect on geometry, even at long range. However, variations in geometry along the ray suggest the importance of horizontal sound-speed changes over the entire propagation range.
Subject Classification: 30.20; 20.25.
Investigation of noise due to structural vibrations using a cross-correlation technique
Authors: Kumar Sudhir , Srivastava Narayan S. 
Published: October 2005

In this paper are presented certain basic considerations of the dependence of noise on vibrations of surfaces. It deals with the problem of cross-correlating vibration and noise for a given system in a semireverberant environment, taking into account the effects of multiple sources of similar character, surface-area contributions, and reflections from the boundaries. Limitations of this approach and the standard error involved are given. Also indicated are expressions for the percentage contribution from the vibration of an individual component to the total noise pressure. The applicability of this method has been demonstrated in an investigation of structural vibration-generated noise of a high-powered diesel engine. It is concluded that the method can be applied successfully to investigate quantitatively the vibration-related noise of a complex machine or structural system, even in a semireverberant acoustic field and in the presence of multiple noise sources of similar character.
Subject Classification: 20.60; 40.20; 45.40.
Scattering by periodic surfaces
Authors: Waterman P. C. 
Published: October 2005

Reflection behavior is examined for an interface having periodic height variation. Upon employing the Bloch theorem, in conjunction with the extended boundary condition, exact matrix equations are obtained for surface fields, as well as transmitted and reflected wave amplitudes. Tunneling considerations then lead to new energy constraints for problems of this type, in which propagating waves are coupled with evanescent modes. In the limit of surface corrugations shallow compared with impinging wavelength, analytic results are obtained confirming both the energy constraints and early computations by Rayleigh. Numerical results demonstrate the efficiency of the method.
Subject Classification: 20.30.
Normal-mode program with both the discrete and branch line contributions
Authors: Stickler D. C. 
Published: October 2005

In a stratified ocean model, in which the sound speed and density become constant as the depth coordinate becomes infinite, the pressure field can be represented as a finite sum of modes plus an integral superposition of modes. This later contribution is given by an integration around a branch cut. In this analysis the sound-speed and density profiles are partitioned in layers such that in each layer the square of the index of refraction can be approximated by a straight line and the density by a constant. The profile is terminated in a high-speed isovelocity half space. Using this profile, it is possible to express the depth-dependent portion of the pressure field in terms of Airy functions. Evaluation of the modal and branch line contributions shows that the branch integral can contribute significantly to the pressure field over a range equal to at least one water depth and in some cases to many water depths.
Subject Classification: 30.20, 30.25.
Tone-burst rod apparatus and experiments
Authors: Hillery H. V. 
Published: October 2005

A tone-burst rod analogous to a fluid-filled pulse tube has been developed for studying audible sound propagation in small solid objects. The apparatus consists of a long aluminum rod driven at one end with longitudinal tone bursts by a small loudspeaker. Instrumentation is provided for measuring the input force, the particle displacement at points along the rod, and the force propagated to the remote end. The interval between the arrival at a displacement probe of outgoing and echo tone bursts is used to determine the impedance of objects attached to the rod. Experiments show that the quality of the mechanical tone bursts is good, the longitudinal wave sound speed in aluminum is largely independent of static tension and frequency, and the acoustical energy propagated along a statically stressed rod departs from the stressed path onto unstressed branch rods.
Subject Classification: 40.85, 40.60.