bluuebunny/crossref_metadata_2025 huggingface dataset:
Fluctuations of N1 Amplitude in Relation to Click-Intensity Discrimination
Authors: Taub Harvey B. , Raab David H.
Published: October 2005

Round-window potentials evoked by clicks were recorded from anesthetized guinea pigs. By comparing N1 amplitudes on line, it was possible to compute physiological difference limens for click intensity. The method requires no assumptions about the underlying distributions of neural effect. Weber functions were generated with and without a continuous masking noise. The effects of click intensity and of background noise paralleled those previously reported for human listeners. A neural model was described in which variability of N1 amplitude turned out to be the principal parameter.
Infrasonic Resonances in Natural Underground Cavities
Authors: Plummer William T.
Published: October 2005

Several examples of acoustic resonance in the frequency range from 0.001 to 1.0 Hz have been observed in limestone caverns. In some cases, the cavern geometry is simple enough for direct application of the Helmholtz resonator theory, and good agreement is found. Three experiments are described. Spectral analysis indicates that subacoustic resonance is responsible for numerous reports of periodically fluctuating or reversing cavern winds, and that appropriate wind measurements can provide new information about chambers not accessible to exploration.
Comments on “Frequencies of a Hanging Chain” [T. Huang and D. W. Dareing, J. Acoust. Soc. Amer. 45, 1046–1049 (1969)]
Authors: Laura Patricio A.
Published: October 2005

The present letter deals with additional references where the same transcendental equations as that discussed by Huang and Dareing is obtained and numerical data is available.
Standing-Wave-Ratio Determination of an Ultrasonic Wave by a Holographic Method
Authors: Alippi A. , Palmieri L.
Published: October 2005

It has been shown how the standing-wave ratio of an ultrasonic field can be obtained by the use of a particular holographic method that permits spatial separation and independent measurement of the light intensities of all the optical subcomponents present in the diffraction spectrum of an ultrasonic grating. Experimental measurements have been performed relative to ultrasonic fields with arbitrary standing-wave ratios, obtained by making use of acoustic transmission lines having particular termination impedances.
Evolution of an Initial Disturbance in a Gas Mixture
Authors: Goldman Edward B.
Published: October 2005

The propagation of initial disturbances in gas mixtures is studied by means of an asymptotic analysis. Three new nonpropagating diffusively damped modes are found to exist in addition to the three modes (two propagating and one nonpropagating) found in a simple gas. Of the three original modes, only the nonpropagating heat-conduction mode is unaffected by diffusion, while the two propagating modes are now diffusively as well as viscously damped. The analysis shows that, in certain mixtures, the diffusive damping can be as large as viscous damping.
Acoustic Rays in Two-Dimensional Rotating Flows
Authors: Salant Richard F.
Published: October 2005

The differential equation of acoustic rays in two-dimensional rotating flows is derived, and is integrated for the cases of rigid-body rotation and the potential vortex, with a point acoustic source. In the case of rigid-body rotation, the rays are bent in the direction of rotation, resulting in defocusing on the side of the acoustic source near the center of rotation and focusing on the opposite side. In the case of the potential vortex, a number of rays are trapped by the vortex and spiral towards the center. Other rays at first appear to be trapped, but then reach a turning point and leave the vortex. These rays are substantially deflected and defocused. In addition, with a circulation corresponding to a Mach number of 0.5 at the acoustic source, a caustic is formed. However, with one-half that circulation, the caustic does not appear.
Reconstruction of Objects from Their Sound-Diffraction Patterns
Authors: Sondhi M. M.
Published: October 2005

A method is presented for reconstructing the shape of an object from a measurement of the diffraction pattern of the object when placed in the path of a monochromatic sound wave. It is shown that measurements of amplitude and phase in a plane at a distance from the object enable reconstruction of the wavefront everywhere. It is further shown that measurements at only a discrete set of points (a square lattice of suitable dimensions) suffice. The results of computer simulation, as well as of an experiment conducted in an anechoic chamber, are presented.
Dynamic Vibrations and Stresses in Composite Elastic Plates
Authors: Cobble M. H.
Published: October 2005

The equation for longitudinal displacement in each of k sections of a composite elastic solid is solved. The elastic composite consists of k discrete plates (separately isotropic), each of different material, joined solidly at their k − 1 interfaces. The composite plates are initially unstressed, and are acted upon, at their two mutual external boundaries, by separate arbitrary time-dependent stresses. The internal boundary conditions maintain across each interface the equality of displacement and stress. The solution is obtained using a new orthogonality relationship. The solution for the displacement given for arbitrary k.
Upper and Lower Bounds on the
N
th Eigenvalue of Vibrating Anisotropic Solids
Authors: Hertelendy Paul
Published: October 2005

Within the context of the linear theory of elasticity, it is shown that, for any arbitrary anisotropic material having up to 21 independent elastic constants, one can compute with relative ease so-called lower-bound and upper-bound isotropic moduli that consistently yield lower and higher eigenvalues, respectively, than the anisotropic material. Computations are carried out for a variety of common cubic, hexagonal, tetragonal, trigonal, and orthorhombic crystalline materials. It is found that the free-vibration frequencies of these materials can usually be predicted by the bounding isotropic moduli with an accuracy of 9.2% or better. The application of such bounds is particularly promising for the numerous boundary-value problems in wave propagation in which exact solutions currently exist only for the isotropic case.
Vibrations of Contoured and Partially Plated, Contoured, Rectangular,
AT
-Cut Quartz Plates
Authors: Lee P. C. Y. , Chen Shoei-sheng
Published: October 2005

Thickness-shear and flexural vibrations and their anharmonic thickness-twist overtones in both contoured and partially plated, contoured, rectangular, AT-cut quartz plates are considered. The plated portion of the plate is of uniform thickness while in the unplated, contoured portion, the thickness varies as an exponential function of the length coordinate of the plate. Analytical solutions are obtained for the case of four free edges. A study is made of the effects on the resonant frequencies and mode shapes of the changes of plate parameters, such as the contouring of the plate, the length of the plating, and the ratio of the length of the plating to the length of contoured portion of the plate.
Time Autocorrelation of Sonic Pulses Propagated in a Random Medium
Authors: Campanella S. J. , Favret A. G.
Published: October 2005

Measurements were made of the random variation produced in the amplitudes of sonic pulses propagated through a water medium in which was induced a nearly homogeneous random perturbation in temperature. The measurements were carried out at frequencies of 480 kHz and 1.42 MHz for transmitter-to receiver separations ranging from 1638 to 7658 in. The amplitude variations of the received pulses were analyzed to determine their time autocorrelation and variance as functions of range, i.e., transmitter-to-receiver separation and frequency. It was found that the time autocorrelation of the sonic-pulse amplitudes was equivalent to that measured for the temperature microstructure. The variance in sonic-pulse amplitude was determined as a function of range at both operating frequencies. These findings are compared with the theoretical findings of Mintzer and Bergmann. An equivalence of the time autocorrelation of sonic-pulse amplitude and temperature microstructure predicted by theoretical considerations is indeed supported by, experimental findings; however, the observed dependence of variance on range fell between the linear dependency predicted by Mintzer and the third-power dependency predicted by Bergmann. This was expected, since the frequency distance and parameters were in between the extremes assumed in those derivations.
Growth of Bubbles by Rectified Diffusion
Authors: Eller Anthony I.
Published: October 2005

A bubble that would ordinarily dissolve in a liquid may instead grow by a process known as rectified diffusion, if it is located in a sound field of sufficient pressure amplitude. Threshold conditions for bubble growth and the rate of bubble growth have been measured for air bubbles in air-saturated water at an acoustic frequency of 26.6 kHz. The experimental results are compared to newly calculated results based on a theory of rectified diffusion by Eller and Flynn [J. Acoust. Soc. Amer. 37, 493–503 (1965)]. The results refer to bubble radii from 15 to 90 μ and pressure amplitudes of less than 0.3 bar. For these conditions, it is found that the experimental and theoretical rectified-diffusion thresholds show rough agreement, but the measured rates of growth, for pressure amplitudes above the threshold, can be much greater than the calculated rates of growth.
Calibration at High Pressure of Piezoelectric Elements for Deep-Submergence Hydrophones
Authors: Henriquez T. A.
Published: October 2005

The acoustic-pressure sensitivities of several types of piezoelectric ceramic and crystal materials have been measured at hydrostatic pressure as high as 16 000 psig. Both disks and hollow piezoelectric ceramic spheres were included in the measurement program, but pressures applied to the spheres were limited to 8000 and 12 000 psig, depending on wall thickness. All measurements were made at room temperature—about 25°C. For many of the ceramic materials, significant differences were noted between the measured sensitivities and the theoretical sensitivities as determined from data supplied by the manufacturers.
On the Free Vibration Modes of an Infinite Thermoelastic Plate Having Isothermal Surfaces
Authors: Mowbray D. F. , Anderson G. L.
Published: October 2005

The free vibration modes of an infinite plate of uniform, arbitrary thickness, based on the linear coupled theory of thermoelasticity are considered. The roots of the transcendental equations relating frequency of vibration, wave-number, and elastic and thermal properties of the material are obtained for isothermal plate-surface conditions. The effect of temperature on the phase speed, the vibration amplitude attenuation, and the thermoelastic energy dissipation are discussed.
Effect of Circumaural Earphone Cushions on Threshold Sensitivity for Speech
Authors: Speaks Charles
Published: October 2005

Threshold sensitivity measures for speech were obtained with a TDH-39 earphone housed in both an MX 41/AR supraaural cushion and a CZW-6 circumaural cushion. The shift in threshold sensitivity for the CZW 6 cushion relative to the MX 41/AR cushion was approximately −3.5 dB. The shift in threshold seemed reasonably constant for three separate tests of speech intelligibility. Corrections for threshold sensitivity for speech cannot be inferred easily from similar data obtained in response to pure tones.
Vocal Loudness and Effort in Continuous Speech
Authors: Brandt John F. , Ruder Kenneth F. , Shipp Thomas
Published: October 2005

The direct-magnitude-estimation scaling technique was used to investigate listener perception of vocal loudness and vocal effort of a continuous speech sample. Three experimental conditions were developed that represented (1) normal changes in loudness and effort, (2) intensity held constant and effort varied, and (3) intensity varied and effort constant. The speech samples were judged by 20 listeners on the magnitudes of loudness and of the amount of effort used by the speaker during phonation. Exponents of the loudness and effort functions (1.12 and 0.57, respectively) suggest that vocal loudness and effort are different percepts of the listener. An examination of the acoustic stimuli suggests that a systematic increase in stimulus bandwidth with an increase in vocal intensity may be related to judgments of both loudness and effort.
Some Pitfalls in Adaptive Testing: Comments on “Temporal Integration and Periodicity Pitch” [R. A. Campbell and S. A. Counter, J. Acoust. Soc. Amer. 45, 691–693 (1969)[
Authors: Creelman C. Douglas , Taylor M. M.
Published: October 2005

Campbell and Counter (1969) measured “thresholds” for various short durations of low-frequency sinusoidal signals. The adaptive psychophysical procedure they used is shown to yield uninterpretable results; values they report can represent a wide range of performance levels. In this note, we take Campbell's and Counter's study as an example of the methodological traps in seemingly straightforward testing methods.
Subject Orientation and Judgment of Distance of a Sound Source
Authors: Holt Robert E. , Thurlow Willard R.
Published: October 2005

Subjects in an open field were not able to judge distance of a loudspeaker source emitting bursts of thermal noise when they were facing the source, but could judge source distance significantly better than chance when their heads were oriented with right ear facing the source, even though there were no loudness cues to distance provided.
Role of Weak Signals in Acoustic Startle
Authors: Hoffman Howard S. , Wible Barry L.
Published: October 2005

When a relatively weak pulse of noise precedes an intense (startle eliciting) stimulus by 5 msec, the latency of the rat's startle reaction to the intense signal is reduced. When, however, the same pulse of noise precedes the intense stimulus by 150 msec, the startle response to the intense stimulus is inhibited. The present research examined the thresholds for these effects using stimulus configurations in which the weak pulse had intensities as low as 10 dB (re 0.0002 dyn/cm2). Both response inhibition and latency reduction were detected when the weak signal had an intensity of only 35 dB, and the magnitude of the two effects increased with increases in pulse intensity. Since, for signals comparable to the pulses used here, the rat's threshold for hearing is approximately 35 dB, it is concluded that the brain system that mediates these effects is probably as sensitive as the auditory system itself.
ON and OFF Responses as Measured in the Cochlea of the Guinea Pig
Authors: Kupperman Roman
Published: October 2005

In order to study the neural behavior of the guinea pig cochlea to repetitive tonebursts of different frequencies, starting and ending with several kinds of acoustical transients, the OFF, response has been investigated in comparison to the ON response as a function of several parameters. It has been found that the OFF response behaves in a way other than the ON response when the frequency of the toneburst is varied and the acoustical transient at both ends of the tone burst is kept constant. It appears that the OFF response is reduced as compared to the ON response in the frequency area between 5000 and 9000 Hz. Outside this frequency band, the OFF response is of the same magnitude as the ON response. We suggest that, in that particular frequency band, the cochlea of the guinea pig is most sensitive while most of the neural elements appear to be in a refractory state as a consequence of the tonal stimulation.
Forward and Backward Enhancement of Sensitivity in the Auditory System
Authors: Moore Thomas J. , Welsh John R.
Published: October 2005

Enhanced sensitivity of the auditory system dependent upon exposure to short (1-msec) acoustic stimuli was investigated. When the dichotic condition was investigated, little or no enhancement was found. When the monotic condition was employed, there was evidence for both forward and backward enhancement. Backward enhancement occured only when the stimulating click was just above threshold [3 dB sensation level (SL)]. Forward enhancement was present to some extent for all intensities of stimulation (3, 10, 20, 40 dB SL) employed.
Lateral Preferences in the Identification of Patterned Stimuli
Authors: Spellacy Frank
Published: October 2005

Sixty-four Ss selected on the basis of a right-ear preference in the recall of dichotically presented words were tested in the recognition of four kinds of dichotically presented nonverbal stimuli: music, timbre, frequency patterns, and temporal patterns. Recognition was tested following 5-sec and 12-sec intervals. A significant left-ear preference was shown in the recognition of musical stimuli following the 5-sec interval only. The ear differences in the remaining stimulus conditions were not significant. The results are interpreted as being consistent with either a perceptual or mnemonic model of stimulus processing in dichotic listening. The significant ear effect was found only in the first half of the experiment, and this is interpreted as evidence that attention is a necessary condition for the demonstration of ear asymmetry.
Nonlinearities in Cochlear Hydrodynamics
Authors: Tonndorf Juergen
Published: October 2005

Cochlear traveling waves show properties of capillary waves, e.g., those progressing along interfaces between two nonmixing fluids. Such wave motion is basically nonlinear for a number of reasons, especially due to the boundary-layer effects associated with surface waves. Mechanical cochlear models display two types of nonlinearities that may explain a number of auditory and/or electrophysiological phenomena: (1) an amplitude-independent asymmetrical displacement that for appropriate signals leads to demodulation; and (2) an amplitude-dependent event, Békésy's eddies, that leads to harmonic distortion. The asymmetry is best observed with beat signals or tone pips. It manifests itself in the perilymphatic fluid motion, the displacement of the partition, and in the shearing motion within the cochlear duct. Of the partition, larger amplitudes are invariably directed away for the input, i.e., toward scala tympani. The demodulation (or envelope detection) is due to the low-pass filtering occurring with distance along the partition. By definition, Békésy's eddies are rectified events. They occur at higher signal levels and distort the ac fluid motion in response to the applied signal in such a way that higher harmonics appear in the traveling-wave pattern. Such harmonics form small localized displacement maxima, each at its appropriate place.
Behavioral Investigation of Some Possible Effects of Sectioning the Crossed Olivocochlear Bundle
Authors: Trahiotis Constantine , Elliott Donald N.
Published: October 2005

Due to the paucity of behavioral data bearing on the possible role of the efferent auditory system, an investigation of some possible functions of the crossed olivocochlear bundle (OCB) has been undertaken, using cats. Behavioral correlates of transection of the crossed OCB were sought in such measures as absolute thresholds in quiet, effective masking over differing noise levels and frequencies, and temporary threshold shifts. The following results were obtained after transection of crossed OCB: (1) Absolute thresholds were unchanged; (2) amount of masking at 1000 Hz and 2000 Hz increased (though the shift was not statistically significant with the small number of subjects tested); and (3) TTS did not differ greatly for the transected animals.
Speaker Identification by Speech Spectrograms: A Scientists' View of its Reliability for Legal Purposes
Authors: Bolt Richard H. , Cooper Franklin S. , David Edward E. , Denes Peter B. , Pickett James M. , Stevens Kenneth N.
Published: October 2005

Can you reliably identify a person by examining the spectrographic patterns of his speech sounds? This is a scientific problem of social consequence because of the interest of the courts in this question. The Technical Committee on Speech Communication of the Acoustical Society of America has asked some of its members to review the matter from a scientific point of view. The topics they considered included the nature of speech information as it relates to speaker identification, a comparison of voice patterns and fingerprint patterns, experimental evidence on voice identification, and requirements for validation of such identification methods. Findings and conclusions are reported; supporting information is given in appendixes.
Simultaneous Measurements of Intraoral Pressure, Force of Labial Contact, and Labial Electromyographic Activity during Production of the Stop Consonant Cognates /p/ and /b/
Authors: Lubker James F. , Parris Pamela J.
Published: October 2005

Simultaneous measures of intraoral pressure, labial pressure, and labial electromyographic (EMG) activity were obtained from 18 normal adult speakers in an effort to provide descriptive data relevant to the supra-glottal characteristics of the English bilabial stops /p/ and /b/. The stops were produced in isolated nonsense syllables such that their position and the vocalic stress varied systematically. The results suggest that (1) the labial gesture for /p/ and /b/ appears to be essentially monotypic, requiring no more forceful labial contact or EMG activity for one than for the other; (2) intraoral pressure provides reliable discrimination between /p/ and /b/, irrespective of consonantal position and vocalic stress, while labial pressure and EMG activity provide relatively poor discrimination; (3) when all three variables are combined, reliable /p/-/b/ discrimination obtained when little or no vocalization follows the stop, and poor discrimination is observed when vocalization follows the stop; (4) a considerable amount of between-subject variability is evident in all three parameters; thus, caution is necessary when making assumptions based upon data of this type.
Physical and Chemical Aspects of Ultrasonic Disruption of Cells
Authors: Clarke P. R. , Hill C. R.
Published: October 2005

An assessment is made of the relative contributions of mechanical and sonochemical effects to damage suffered by mammalian cells when sonicated in aqueous-suspension culture. In a 1-MHz progressive wave beam, under conditions providing stabilization of the cavitation field, the intensity threshold and intensity optimum for cell disintegration occur at about 1 and 5 W cm−2, respectively, and the same pattern is found for the liberation of free iodine in solutions of KI. The cell culture medium is, however, found to have a chemiprotective effect on the cells, probably as a result of successful competition for OH radicals on the part of glucose and amino acid constituents of the medium. Thus, although prolonged sonication of the medium can eventually reduce its ability to support cells, such indirect effect is insignificant the relatively short irradiation times required to kill 99% of cells and the primary mechanism of damage here appears to be mechanical. Pulsing conditions have an important influence on both cell disintegration and iodine-release rates, which both show maxima for 30-msec pulse duration and drop to zero for pulse durations below 1 msec. The relevance of this finding to the kinetics of cavitation mechanisms discussed.
Auditory and Electronic Envelope Periodicity Detection
Authors: Filip Miroslav
Published: October 2005

There are some functional analogies between electronic envelope periodicity detection and processes in the cochlea associated with the periodicity pitch perception. The discussion is concerned with the missing fundamental and residue pitch. monaural phase and envelope effects, pitch of inharmonic complexes, beats of mistuned consonances, time-separation, and interruption pitch. As a simplified simulation of the lowest stages of periodicity pitch perception, particularly temporal aspects of the mechanical-to-neural transduction, an array of unipolar envelope periodicity detectors distributed along a basilar-membrane analog is suggested. Various explanations of psychophysical and physiological experimental results and models presented in the literature are briefly surveyed to show their essential agreement with the envelope periodicity-detection concept.
Further Evidence for Peripheral Activation of Olivocochlear Bundle Endings
Authors: Nieder P. , Nieder I.
Published: October 2005

Function of the olivocochlear bundle (OCB) has been studied in anesthetized guinea pigs, using differential cochlear recording. Low rates of efferent bundle stimulation (EBS) are highly effective in equalizing the two microphonic modulation envelope maxima (peaks) seen in the double modulation response to two-tone stimulation. EBS pulses, time-locked to a 20-Hz modulating tone, are effective in increasing the amplitude of the smaller peak of a 400-Hz double modulation response, provided they occur during the time interval of the larger peak. Using sequential two-tone stimuli, it has been found that there is a transient period of microphonic enhancement immediately following a short burst of moderately intense low-frequency tonal stimulation. The increase of the microphonic response to a weak test tone presented immediately after a low-frequency tone pip is similar in both amplitude and rate of decay to that produced by crossed olivocochlear bundle (COCB) stimulation. The microphonic enhancement effects produced by low-frequency tonal stimulation and low-rate COCB stimulation are additive; higher frequency tones—e.g., 1000 Hz—reduce the microphonic enhancement effectiveness of COCB stimulation when presented concurrently. These findings suggest peripheral reflex mechanisms for firing OCB endings.
Method of Observation of Glottal-Source Wave Using Digital Inverse Filtering in Time Domain
Authors: Nakatsui Mamoru , Suzuki Jouji
Published: October 2005

An attempt to observe the glottal-source wave by the digitalized inverse filter in the time domain is described. An observation system having an inverse characteristic of the vowel transfer function is realized in the form of the sampled data equivalence. It is found that the observed waveforms are good representatives of the voiced source signal in the analysis-synthesis experiment in speech study.
Sound Transmission through Double Panels Using Statistical Energy Analysis
Authors: Price A. J. , Crocker M. J.
Published: October 2005

Statistical energy analysis is used to study the transmission of random-incidence sound waves through two independent panels separated by an air space. The analytical model consists of five linearly coupled oscillators arranged, room-panel-cavity-panel-room. Both nonresonant and resonant transmission for the panels are included. The cavity is considered to behave as a resonant system and its modal density and loss factor are determined, analytically. Absorption material is placed around the edges of the cavity. The sound energy transmitted is found to be strongly dependent upon the radiation resistance of the panels, the panel spacing, and the panel and cavity loss factors. Agreement between the theoretical results and experiments for several different double panel systems is found to be good.
Generation and Detection of Sound by Distributed Piezoelectric Sources
Authors: Mitchell R. F. , Redwood M.
Published: October 2005

This paper develops a theoretical method of obtaining the frequency response and electrical equivalent circuit of piezoelectric sources and detectors in which the piezoelectric stress hD is not spatially uniform. A wave equation is derived from a one-dimensional formulation of the piezoelectric relations, and Green's functions are used to obtain solutions for the generated stress waves in terms of the Fourier transform of the spatial distribution of piezoelectric stress. Both acoustically matched and unmatched sources are treated. The complex electrical impedance is also developed. Expressions are obtained for the voltage and current generation in detection, and conditions for maximum power transfer are considered. Illustrative examples include sources with uniform, sawtooth, and Gaussian distributions of piezoelectric stress, both matched and unmatched. Optimization of response by choice of source distribution is illustrated. Arrays of sources are also treated, both with and without piezoelectric interactions between sources.
Interfacial and Love-Type Waves in Materials with Monoclinic Elastic Symmetry
Authors: Gou Perng-Fei
Published: October 2005

The existence of interfacial and Love-type waves in materials with monoclinic elastic symmetry is shown, if the displacement is in the direction of the digonal axis of a monoclinic crystal.
Stability of Acoustic Waves within a Viscous Compressible Heat-Conducting Fluid
Authors: McKinney J. E. , Oser H. J.
Published: October 2005

The question of stability of propagation of acoustic waves within a continuum of compressible viscous heat-conducting fluid has been investigated. A bounded solution (i.e., a stable solution) is assured if either of the following two conditions is satified: γ = 1 (i) or 3(2 − γ)4[1 + (3/4)(υ/η)]P⩽ 1 (for γ> 1), where P is the Prandtl number, γ the ratio of specific heats, and υ and η the bulk and shear viscosities, respectively. According to the theory, the above inequality must be obeyed for all passive fluids with γ> 1. Using experimental values for many different fluids, it appears to be generally obeyed except for the molten metals including mercury and, possibly, the superfluids.
Piezoelectric and Photoelastic Properties of Lithium Iodate
Authors: Warner A. W. , Pinnow D. A. , Bergman J. G. , Crane G. R.
Published: October 2005

Considerable interest has recently been drawn to the iodates owing to the large nonlinear optical interactions (second harmonic and photoelastic) reported in α-HIO3. In the present work, many of the photoelastic and piezoelectric constants and related properties of single-crystal lithium iodate LiIO3 have been determined. The acousto-optic figure of merit for LiIO3 has been found to be only about 15% of that for α-HIO3, making the material unattractive as an acousto-optic medium. However, LiIO3 has been found to have a rare combination of a large piezoelectric effect (kt=0.51, k15=0.60) and low dielectric constant (ε33S/ε0≅6, ε11Sε0≅8), which makes it particularly attractive for broad-band high-frequency transducer applications.
Curvature Corrections to Rough-Surface Scattering at High Frequencies
Authors: Lynch P. J.
Published: October 2005

A variational principle is constructed for the problem of acoustic scatter from a rough surface. The use of the physical-optics approximation as trial function leads to an improved expression for the surface field on the illuminated surface, although the form of the curvature dependence at least implies the “penumbra” or transition width near grazing incidence. Its application to the theory of scattering from very rough random surfaces yields an angular distribution proportional to the probability density of slopes, but for a fictitious surface with rms slope dependent on the wavelength. This scattering distribution is corrected for a shadowed surface.
Asymptotic Nature of Extensional Waves in an Infinite Elastic Plate
Authors: Nariboli G. A. , Tsai Y. M.
Published: October 2005

A theory based on a perturbation method is constructed to describe extensional waves and stress distributions in an infinite elastic plate of finite thickness. The plate is subjected to arbitrary axisymmetric disturbances, which are loadings located symmetrically at the surfaces of the plate, and in-plate disturbances distributed symmetrically with respect to the plate's midplane. The displacements and stresses are expanded by infinite series of a small parameter and are required to satisfy the three-dimensional equations of motion. The equation of motion for the first-order terms is derived, and the disturbance is shown to propagate at the plane-stress wave speed. For a given order higher than 1, correction terms can be obtained to modify the first-order equation of motion and field variables. An equation describing a type of dispersive wave motion in any number of dimensions is also considered. A self-similar solution of this equation is presented that represents the farfield nature of the waveform. The solutions are products of two parts. One gives the decay law and the other is in terms of Airy function. The latter shows the modification of the sharp wavefront by dispersion.
Normal-Mode Vibrations of Systems of Elastically Connected Concentric Rings
Authors: Stead K. A. , Liu J. , Hoppmann W. H.
Published: October 2005

This paper presents the development and solution of the differential equations of flexural vibrations of a system of n elastically connected concentric rings. By using these equations, the particular case of a two-ring system is analyzed in detail. The frequency equation and displacement functions are then presented. The analysis includes a consideration of the effect of rotatory inertia. Vibration experiments were made on physical model of the two-ring system. The results are compared with results of calculations based on the theory. An interesting phenomenon encountered during the investigation suggests the possibility of exciting, at a definite frequency, patterns of displacement that probably represent the combination of two normal modes.
Modified Ray Theory for the Two-Turning-Point Problem
Authors: Murphy E. L.
Published: October 2005

A wavelength-dependent modified ray theory is developed to represent the reflected and transmitted fields for a harmonic point source located in a medium having a maximum in sound velocity and giving rise to the two-turning-point problem. In a stratified inhomogeneous medium with index of refraction n(z) a function of z only, the wave equation can be separated. The undifferentiated term in the separated z equation has a factor (n2−a2) in its coefficient, where a is the separation constant. The geometrical-optics approximation fails in the neighborhood of the zeros (turning points) of this coefficient. The two-turning-point problem arises when n(z) has a minimum and there are two z values at which the coefficient is zero. A generalization of the WKB procedure based on Weber's functions is used to construct approximate solutions valid throughout the two-turning-point regions. These solutions are then applied to the construction of a contour integral representation for the field of a harmonic point source. A stationary phase condition on the integrand is invoked to develop, formally, a modified ray theory to represent the field in reflection and transmission regions. There are elements in the phase that depend on the separation constant a and lead to significant modifications of the ray scheme based on the stationary phase condition.
Circumferential Waves on Hollow Aluminum Cylinders
Authors: Marshall S. W. , Olson T. G.
Published: October 2005

Recent experimental data presented by Bunney et al. indicate that, as an originally solid cylinder is progressively made hollow, the circumferential acoustic waves that can be excited on that cylinder progress from those having the characteristics of Rayleigh waves to those having the characteristics of Lamb waves. Similar measurements of circumferential wave velocity have been made on a different type of aluminum alloy, type 1100F, and it was found possible to excite both the Rayleigh-type and the Lamb-type waves, over a limited region of wall thickness, by adjusting the angles of incidence of the projector and receiver.
Effect of Forward and Backward Masking on Speech Intelligibility
Authors: Dirks Donald D. , Bower Deborah
Published: October 2005

Monaural-intelligibility functions for monosyllabic words were obtained for seven subjects with normal hearing under the following major experimental conditions: (1) speech interrupted by silence at the rates of 1, 10, and 100 interruptions per second (ips); (2) speech alternating with noise (80 dB SPL) at rates of 1, 10, and 100 ips; (3) speech in interrupted noise (80 dB SPL) at rates of 1, 10, and 100 ips. The comparison between the intelligibility functions for Conditions 1 and 2 yielded a measure of the effects of forward and backward masking during the noise-free interval. The comparison between the intelligibility functions for Conditions 2 and 3 yielded a measure of the extent to which the speech signal during the noise burst contributed to intelligibility. The results indicated that the effect of forward and backward masking on intelligibility was substantial at 10 ips and even more pronounced at 100 ips. However, at 1 ips little masking effect was observed except at very adverse signal-to-noise (S/N) ratios. The findings also demonstrated that the speech heard within the noise burst contributed to intelligibility at favorable S/N ratios when the noise was interrupted one time per second. At 100 ips, the speech signal within the noise burst made only a small contribution to the total intelligibility score, and at 10 ips the function was formed almost entirely by the speech heard during the noise-free intervals.
Effect of Calcium Deficiency on Cochlear Potentials
Authors: Konishi Teruzo , Kelsey Elizabeth
Published: October 2005

Calcium deficiency in the cochlea was induced by perfusing the perilymphatic space with calcium-deficient solutions in guinea pigs. The effect of calcium lack in the perilymph on the cochlear potentials and on the activity of crossed olivocochlear bundle was studied. Removal of calcium caused a reversible depression of action potential and a slight decrease of cochlear microphonics. The endocochlear potential did not show depression. These changes were enhanced by addition of disodium ethylenediamine-tetraacetate. Calcium lack in scala tympani affected cochlear potentials more severely than that in the scala vestibuli. The removal of calcium from scala tympani blocked the slow negative potential in the scala media produced by crossed olivocochlear bundle stimulation. Calcium deficiency in scala tympani failed in augmentation of cochlear microphonics, suppression of action potential, and increase of positive summating potential produced by olivocochlear bundle stimulation. The role of calcium in the transducer action and the synaptic transmission of crossed olivocochlear bundle was discussed.
Choice of Sound Duration and Silent Intervals for Test and Comparison Signals in the Subjective Measurement of Loudness Level
Authors: Reichardt W. , Niese H.
Published: October 2005

To avoid faulty judgments when making subjective loudness-level measurements of noises, the time function of the 1000-Hz reference tone should be adjusted, as far as possible, to that of the test noise. For trains of repeated impulsions, it should be arranged to have the same duration of impulsion, the same duration of silence between them, the same repetition rate, and the two signal trains should be presented for the same length of time. For continuous noises, these signals should be presented with the same duration, in the range 250–500 msec and with silent intervals of 500–1000 msec. The loudness level of the 1000-Hz reference tone when presented in very short bursts is to be modified in accordance with the findings of this paper and these findings should be incorporated in the next issue of ISO recommendation 131.
On the Role of Phase in the Audibility of Octave Complexes
Authors: Schubert Earl D. , Nixon James C.
Published: October 2005

The preponderance of evidence bearing on the detection of signals in noise indicates that detection takes place after at least a limited (critical-band) frequency resolution. However, a study reported by Fricke in 1968 suggests that two-tone octave waveforms are considerably more detectable for certain phase relations of the two components than for others. Such a result is understandable only if one postulates detection of the complex waveform prior to frequency separation. In addition, recent reports of recordings of first-order auditory neurons indicate that an analog of the complex waveform appears at the first neural coding. The study reported here is essentially a repeat of the Fricke study. For each set of waveforms compared, the energy was kept constant and only the phase relations changed. One set consisted of two equally detectable components; the other, of two components with supposedly equal displacement amplitude at the locus in the cochlea normally maximally responsive to the higher frequency. In neither case was there a difference between waveforms of different phase relation large enough to be attributed to factors other than chance variation. If there are differences in the detectability of two-tone harmonic signals of the same energy but different waveform, this study indicates they are quite small.
Duration of /s/ in /s/-Plosive Blends
Authors: Schwartz Martin F.
Published: October 2005

The purpose of this study was to examine the duration of /s/ in /s/-plosive blends. Three consonants (/p/,/t/,/k/) and two vowel environments (/i/,/ɑ/) were considered. The results, obtained from 10 females, showed differential influences of both the vowel and the consonant upon the duration of the /s/.
Survey of Literature on Reflection and Scattering of Sound Waves at the Sea Surface
Authors: Fortuin Leonard
Published: October 2005

The problem of diffraction of waves at uneven surfaces has received increasing attention in the past 15–20 years. This has resulted in a large number of reports and papers in the open literature. In this review article most of the publications dealing with sound waves and pressure release surfaces (both theoretical and experimental) that appeared up to the beginning of 1969 are mentioned as references. They are classified by subject, and the main currents in the literature (Rayleigh and Uretsky method for sinusoidal boundaries, Eckart theory with Kirchhoff approximation for random surfaces, experiments at sea) are analyzed and discussed. General trends, relations between studies, agreements, and contradictions are mentioned. It is found that nearly all of the publications cover only part of the problem: although the wave diffraction at rough surfaces is a function of three basic quantities simultaneously (i.e. time, frequency of incident wave, and geometry), most of the papers deal with only one or another of these three variables. Possible directions of future research are indicated.
Light Diffraction by Ultrasonic Surface Waves of Arbitrary Standing-Wave Ratio
Authors: Hallermeier Robert J. , Mayer Walter G.
Published: October 2005

The diffraction of monochromatic light by reflection off a single-frequency ultrasonic surface wave of arbitrary standing-wave ratio is analyzed theoretically, with the assumption that the light and sound beams share a direction of symmetry. The diffraction integral is solved for the case in which the surface illumination has a uniform intensity cross section, and also for a Gaussian intensity cross section. The dependences of the diffracted light intensities in the limiting case of small sound-beam intensity are examined in detail for varying standing-wave ratios.
Sound Absorption in Pure D2S and CO2/D2S Mixtures
Authors: Shields F. Douglas , Carney George P.
Published: October 2005

Sound absorption measurements in pure D2S at 300° and 400°K indicate a vibrational relaxation with a relaxation time of 4.8 × 10−8 sec⋅atm, which is independent of temperature. The mixture measurements, when compared with theoretical curves calculated for a series relaxation process, indicate that energy is exchanged between the excited vibrational levels of the two molecules. The results confirm the theory that the bending vibration in CO2 exchanges energy primarily with the rotational motion of the D2O molecule in a collision.
Experimental Study of Sound-Wave Phase Fluctuations Caused by Turbulent Wakes
Authors: Schmidt Dieter W. , Tilmann Peter M.
Published: October 2005

Ultrasonic waves were sent through the wakes of circular cylinders of certain simple profiles and of plates in air flow. By application of multichannel pulse-height analysis, probability density distributions of the sound-wave phase fluctuations (“phase spectra”) were measured. One gets Gaussian distributions in cases of purely turbulent flow and characteristically shaped curves (most often with two maxima), if, additionally, the wake flow contains discrete vortices. The computer-aided evaluation of the phase spectra allows, simultaneously, determination of the magnitude of the turbulent motion in direction of the sound-wave propagation and the circulation of the vortices and, furthermore, leads to information about the general structure of the flow.
Perturbation Solution of a Hyperbolic Equation Governing Longitudinal Wave Propagation in Certain Nonuniform Bars
Authors: Wingate Robert T. , Davis R. T.
Published: October 2005

A perturbation method is used to analyze wave propagation in a class of variable-section bars that can be treated as a perturbation of a uniform bar. The hyperbolic equation of motion is shown to constitute a singular perturbation problem. An existing perturbation method is modified and extended to obtain a uniformly valid asymptotic expansion of the solution.
Penetration of a Sonic Boom into Water
Authors: Cook Richard K.
Published: October 2005

An aircraft in level flight at a supersonic speed over water produces a sonic-boom pressure on the water surface. Usually the N wave of the incident sound pressure moves across the surface at a subsonic speed, relative to the speed of sound in water. Therefore, the boom energy is totally reflected, and the sound pressure in the water falls off with depth below the surface. The penetration depth, comprising well over half of the underwater energy, is about the same as the N-waveform length on the surface. The analysis shows further that the wave reflected into the atmosphere has (a) two infinitely large pressure spikes at the leading and trailing edges of the N wave, and (b) a weak precursor and a weak tail. The same is true of the underwater wave just at the surface. The spikes, precursor, and tail have positive sound pressures and are even functions of distance from the center of the N wave.
Closed Solution for the Initial Target-Acquiring Angle at the Source Depth in a Linear-Gradient Ocean
Authors: Raphael David T.
Published: October 2005

A closed solution for the initial target-acquiring angle θ0 at the source depth in a linear-gradient ocean is obtained for the case involving no surface or bottom reflections. The solution for θ0 is a function of the known source and target coordinates in the ray-path plane, the ray velocity at the source, and the velocity gradient. The equation for the intensity at the moment of acquisition is derived in a closed form through the use of the above acquiring-angle solution.
On the Rayleigh Equation for Elastic Surface Waves
Authors: Aggarwal H. R. , Ablow C. M.
Published: October 2005

Using a simple argument, the roots of the Rayleigh equation for an elastic material with real wave speeds are investigated. It is shown that, besides the known root lying between 0 and 1 for values of Poisson's ratio less than or equal to 12, the equation also has an admissible root for a Poisson ratio greater than 1. The new root is negative and leads to motions that die away with distance from the surface, but grow exponentially with time at any given point of the half-space.
Further Numerical Results on the Plane-Strain Vibrations of Two-Layered Elastic Cylinders
Authors: Chi Michael
Published: October 2005

This is a sequel of a previous report on the layered elastic cylinder in plane-strain vibrations. Numerical results for lobar mode numbers n = 2, 3, and 4 are presented and analyzed. The transition from the vibrations of thick-walled cylinders to the shell vibrations is investigated. Practical implications of the numerical results are indicated.