bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Solid Impurities on Cavitation Nuclei in Water
Authors: Messino' C. D. , Sette D. , Wanderlingh F.
Published: October 2005

In order to investigate the effect of solid impurities on cavitation, the distribution functions of nuclei were studied in water samples that had various impurities and were differently treated: filtered, placed under a lead screen, de-ionized, or with addition of uranyl nitrate. We have used two kinds of impurities : wettable particles (emery and corundum) and unwettable particles (Teflon). Although the results give support to Harvey's stabilization theory, the action of impurities is not simply a stabilizing one; the impurities play an active role in determining the shape of the distribution functions. The unwettable impurities cause a production of large-size nuclei, while the wettable ones destroy large nuclei and increase the concentration of small nuclei. A phenomenological treatment of the mentioned effect is suggested.
Magnetoacoustic Attenuation in Liquid Gallium to 150 kG
Authors: Shapira Y.
Published: October 2005

The magnetic-field variation of the attenuation of 8.5-, 24-, and 56-Mc/sec sound waves propagating in liquid gallium was measured in fields up to 146 kG. The attenuation was found to increase monotonically with field and is in good agreement with the predictions of Anderson's theory.
Forced Vibrations of Submerged Spheroidal Shells
Authors: Yen Timothy , DiMaggio Frank
Published: October 2005

The extensional displacements of prolate spheroidal shells and the pressure field in the surrounding fluid are obtained as a function of the driving frequency of an axisymmetric, distributed, harmonic load applied to the surface of the shell. By appropriate transformations of response functions and a geometric variable, the problem is reduced to the simultaneous numerical integration of equations on analytic functions in a finite domain. Numerical results are presented for an aluminum shell of moderately large eccentricity submerged in water.
Efferent Inhibition in the Cochlea Related to Hair-Cell dc Activity: Study of Postsynaptic Activity of the Crossed Olivocochlear Fibres in the Cat
Authors: Fex Jörgen
Published: October 2005

Intracochlear dc potentials were evoked by stimulating the crossed olivocochlear fibres and were recorded with microelectrodes in 28 cats. From the organ of Corti to the scala media, the dc potentials changed from positive to negative and became larger by a factor of 4–10, reaching −3 mV relative to a reference electrode outside the cochlea. It is concluded that the dc potentials represented postsynaptic activity, generated by crossed olivocochlear fibres impinging on outer hair cells, and that auditory-nerve fibres are presynaptically inhibited by such activity. New and previous findings on the action of the crossed olivocochlear fibres are discussed in relation to present concepts of summating potentials. The findings that centrifugally and acoustically evoked dc activity interact are taken to indicate that sound-evoked dc activity in hair cells might regulate activity in auditory nerve fibres. New and previous findings on the uncrossed olivocochlear fibres are discussed. The tentative hypothesis is proposed that these fibres inhibit by their action on the afferent terminals underneath the inner hair cells, and perhaps in no other way.
Masking of White Noise by Pure Tone, Frequency-Modulated Tone, and Narrow-Band Noise
Authors: Young I. M. , Wenner C. H.
Published: October 2005

Threshold measurements were made by Békésy audiometry for white noise in the presence of pure tones, frequency modulated tones, and narrow-band noises in normal ears. Pure tones in the frequency range of 700–1000 cps caused maximal masking. When the masking tone had a high distortion factor (13 dB below the fundamental), the masking effect was greater than that for undistorted tones, and was centered between 300 and 400 cps at 120 dB SPL and 500 cps at lower intensities. Tones with a distortion factor of 30 dB or more below the fundamental produced masking effects indistinguishable from pure tones with the distortion factor greater than 70 dB below the fundamental. The masking peak at 800 cps may be explained on the basis of mechanical resonant frequency. While there was some intersubject variation in the masking of white noise by frequency-modulated tones, the maximum effect obtained by frequency-modulated tones was centered at 800 cps, as is the case with pure-tone masking. The masking effect was independent of modulation rate and frequency deviation. Narrow-band noise centered near 2000 cps produced the greatest masking effect on white noise. Greater masking—both in shift and spread—was obtained from a narrow-band noise produced by a commercial noise generator than by Zwicker's narrow-band noise with a cutoff slope of 60 dB/oct.
Farfield Spectrum of the Sonic Boom
Authors: Howes Walton L.
Published: October 2005

The pressure spectrum of the sonic-boom N wave is simply given by P (ω) = (2π)−12TP(T)j1(ωT/2), where T is the boom duration, P(T) is the pressure amplitude, and j1(ωT/2) is a spherical Bessel function of the first kind and order. The effective acoustic period of the N wave is approximately 32 times its duration. The present formulation is a simplification of those by Crocker and Young. The spectrum formula given by Zepler and Harel is incomplete.
Detection of an In-Phase Signal with and without Uncertainty Regarding the Interaural Phase of the Masking Noise
Authors: McFadden Dennis
Published: October 2005

The basis for detection in those interaural conditions that lead to a masking-level difference (MLD) is presumed to be quite different from that in the non-MLD conditions. This experiment examined the effect upon detectability when listeners were uncertain whether an MLD or a non-MLD condition was to be presented. Detectability was measured at two values of signal energy for each of two interaural conditions, N0-S0 and Nπ-S0. The “YES-NO” psychophysical method was used. On some blocks of trials, the blocks with “no uncertainty,” only one interaural condition was presented. On other blocks of trials, the blocks “with uncertainty,” N0-S0 signals were mixed with equally detectable Nπ-S0 signals. The listeners were informed which type of block was to be presented. There was essentially no difference between the data obtained with uncertainty and those obtained with no uncertainty. A supplementary experiment showed that on the blocks with uncertainty the listeners were quite poor at identifying the type of noise presented on a trial.
Comment on “Linear Versus Logarithmic Averaging”
Authors: Mitchell Stephen K.
Published: October 2005

The difference between the average logarithm of a set of data and the logarithm of the average value may be determined for data whose statistical distribution is known. Example distributions are considered and the results are compared with the limiting value obtained by Cox.
Determination of the Geometry of the Human Vocal Tract by Acoustic Measurements
Authors: Schroeder M. R.
Published: October 2005

The geometry of the human vocal tract from the glottis (vocal cords) to the lips is one of the determining factors in human speech production and basic to a better understanding of articulation. Measurement of the vocal-tract geometry is difficult, especially that of its time-dependent behavior during connected speech utterances. Practically the only tools that have been available in the past for such measurements are radiography and cinéradiography. Unfortunately, radiographic measurements and their evaluation are laborious. In addition, adequate cinéradiography for longer utterances poses severe problems owing to dosage limitations. Alternative methods of obtaining information on the vocal-tract geometry have therefore always remained a desideratum. In this paper, it is shown that some of the desired vocal-tract-shape information can be obtained by purely acoustic measurements. Two kinds of acoustic methods are discussed in some detail: measurement of the eigenfrequencies (formants) of the vocal tract and measurement of the acoustic impedance at the lips. Both measurements allow the determination of an approximation to the cross sectional area of the vocal tract as a function of distance along its axis. More specifically, if the logarithm of the area function is described by a Fourier series, these measurements allow the determination of certain terms of the Fourier series. The number of terms, and therefore the spatial resolution of the approximation, increases with the number of measured eigenfrequencies of the tract or with the number of measured singularities of the impedance function. Both methods are applicable to dynamic measurements during nonstationary utterances and hold promise for supplying large amounts of area data necessary for specifying or refining articulatory models of speech production. The results can be portrayed by computer-drawn single frames or motion pictures of the acoustically derived area functions.
Audio-Frequency Measurements of the Viscoelastic Properties of Polydimethylsiloxane Liquids
Authors: Lamb J. , Lindon P.
Published: October 2005

Results of previous measurements of the viscoelastic behavior of a range of polydimethyl siloxane liquids at frequencies of alternating shear stress above 10 kcps have been shown to be in agreement with theoretical predictions based upon modifications of the Rouse theory. The higher-molecular-weight members of this series exhibit entanglement coupling, giving rise to a plateau in the curves of G′ and G″ (the components of the complex rigidity modulus) versus frequency, centered around a frequency of 1000 cps. The existence of this plateau region is a factor of considerable importance in the theoretical analysis and interpretation. Previous measurements did not extend into this region, for the lack of a suitable experimental technique and the shear properties at these lower frequencies, in the audio range, were deduced from the measured behavior at higher frequencies. The evidence in support of this extrapolation procedure was good and self-consistent but lacked experimental verification. This has now been provided by shear-wave measurements obtained over the frequency range 20–1500 cps on four of the polydimethylsiloxane liquids used previously having viscosity grades from 1000 to 100 000 cS. Excellent agreement is found between the results now obtained and the previous theoretical predictions, which have not been modified in any way. The design, construction, and performance of the new experimental system is described. It is based upon torsional shearing of an annulus of liquid placed between an inner rigid cylindrical plug and an outer cup. Separate electromagnetic excitation and detection systems are used, and the theory of the measuring procedure is described. It can be used to measure liquids with steady flow viscosities exceeding 1 P.
Dislocation Relaxations in Single-Crystal and Polycrystalline Niobium and Tantalum at Megahertz Frequencies
Authors: Mitchell O. M. Mracek
Published: October 2005

Maxima in the attenuation of longitudinal ultrasonic waves (10–60 MHz) as a function of temperature due to a dislocation-relaxation mechanism have been observed in plastically compressed single-crystal Nb and polycrystalline Ta in the temperature range 150°–400°K. In single crystal Nb with the wave propagation in a [110] direction, the peak at 10 MHz is at 318°K and at 30 MHz is estimated to be at 370°K. In polycrystalline Ta, the peak at 10 MHz is at 291°K. The peaks are unstable at temperatures above 350°K, where a low-temperature recovery takes place. The peaks at megahertz frequencies have widths approaching the theoretical values for a single-relaxation process. The peak temperatures and frequencies are compared in Arrhenius plots for Nb and Ta to data by other investigators for the α peaks for a wide range of frequencies.
Anharmonicity in Sodium Chloride
Authors: Swartz Karl D.
Published: October 2005

The full set of third-order elastic constants of NaCl was measured and compared to some combinations of these constants that have been reported in the literature. The Cauchy relations were found to be reasonably well satisfied. For NaCl, C111 is large (of the order of 1013 dyn/cm2) and negative, C112 and C166 are smaller (of the order of 0.5×1012 dyn/cm2) and negative, and C123, C456, and C144 are small (of the order of 1011 dyn/cm2) and positive. It is shown that the closed-shell repulsive interaction between nearest and next-nearest neighbors gives the major contribution to the third-order elastic constants of NaCl and completely dominates the contributions to the fourth-order elastic constants. These fourth-order elastic constants are evaluated from the experimentally measured temperature coefficients of the second-order elastic constants. The Grüneisen parameter of 1.588 calculated from the measured second- and third-order elastic constants compares well with the Grüneisen constant of 1.64 obtained from thermodynamic measurements. Comparison of the third-order elastic constants obtained with linear combinations given by other methods shows that the two-specimen method used here gives results in fair agreement with one-specimen ultrasonic methods but not with optical methods.
Calculation of Lattice-Parameter Changes with Hydrostatic Pressure from Third-Order Elastic Constants
Authors: Thurston R. N.
Published: October 2005

Part I describes the calculation of the first and second pressure derivatives of the lattice parameters from the second- and third-order elastic constants (or from the second-order constants and their pressure derivatives). These derivatives determine only the linear and quadratic terms in the expansions of the lattice parameters as power series in the pressure. The quadratic expressions obtained by truncating the power series are not suitable for extrapolation beyond a few tens of kilobars.

Part II gives extrapolation formulas that turn out to be far better than the truncated power-series expansions. For quartz, magnesium, and cadmium, the resulting extrapolation from ultrasonic data taken at low pressures is found to be in reasonable agreement with x-ray determinations of the lattice parameters out to well over 100 kbar.

Appendix A includes derivations of all the formulas needed to make the extrapolation from ultrasonic and thermal data. Complications arise not only from the distinction between adiabatic and isothermal coefficients, but also from the distinction between “effective” and “thermodynamic” coefficients.
Complete Solutions of the “Webster” Horn Equation
Authors: Eisner Edward
Published: October 2005

Suppose that one solution of the “Webster” equation for any given horn is known, valid for particular boundary conditions and at one frequency. Expressions for the other linearly independent solution and for the derivatives of both solutions with respect to frequency are deduced and given in computable form. This allows the behavior of the horn for any loading, and in a wide range of frequencies, to be derived from a solution with one loading, at one frequency. The originally known solution may be computed, or experimental, or it may be the initial wavefunction in the inverse method of horn design (where the horn contour is derived from the initial wavefunction, which is constructed to satisfy the design requirements). With the new results, it is straightforward to compute the behavior of horns that were designed by the inverse method (for example, the “Terminated Gaussian” and the “Fourier”) in conditions not envisaged in their design. Further, the inverse method can now be used to design new horns with specified characteristics at a number of loads (including dissipative toads) and frequencies. The impedances of horns are discussed in the light of the relation between the solutions of Webster's equation, with special reference to the ideal transformer. The general impedance relations are thereby considerably simplified. Some basic results of the theory of horns are briefly reviewed and an annotated bibliography of over 200 references is given. Attention is drawn to very important work on the horn equation and its solution—long before Webster—in particular to brilliant papers by Daniel Bernoulli, by Lagrange, and by Euler in the 18th century.
Solid Torsional Horns
Authors: Pyle Robert W.
Published: October 2005

The propagation of torsional waves in tapered solid elastic rods is examined both theoretically and experimentally from the viewpoint of acoustic horn theory. Such tapered rods in torsional vibration are dubbed torsional horns. Two differential equations are derived that describe the propagation of torsional waves. One of these is an “exact” wave equation that can be readily solved only when the horn boundaries fit a separable coordinate system. The other is an approximate wave equation based on the assumption that the wavefronts are plane cross sections of the horn. This equation is very similar to Webster's plane-wave equation for compressional waves in an acoustic horn. Experimentally determined standing-wave patterns and resonance frequencies of torsional horns are compared with the solutions of the two wave equations for selected horn contours. A quantitative estimate of the error introduced by the plane-wave approximation is obtained for the exponential horn.
Analysis of Multiterminal Piezoelectric Plates
Authors: Holland Richard
Published: October 2005

Mathematical techniques are discussed whereby one may analyze a thin piezoelectric plate with arbitrary electrodes, external electrical loads, and external mechanical tractions. These techniques include tensor Green's-function operations, Fourier-eigenmode expansions, and circuit-theory manipulations. Application of these techniques leads to admittance matrices interrelating the linear responses of the various mechanical terminals (i.e., the sites of external-force application) and electrical terminals (i.e., electrodes). It is demonstrated that these admittance matrices may be represented by quite simple equivalent circuits. External mechanical forces may be applied either at a point or over a distributed area. These two types are represented best by separate methods, both of which are discussed here. Two specific, nontrivial examples of actual piezoelectric devices are analyzed at the conclusion of this work, and results are compared with experimental observations. These examples are a symmetrically electroded ferroelectric ceramic disk bonded to a substrate and an asymmetrically electroded, mechanically free, ferroelectric ceramic disk. Effects due to loss, nonuniform density, and nonuniform material coefficients (elastic, dielectric, and piezoelectric) have been included in this work. However, finite-plate-thickness effects, such as electrical fringing and particle accelerations perpendicular to the plane of the plate, are not included.
Useful Formulas for Piezoelectric Ceramic Resonators and Their Application to Measurement of Parameters
Authors: Onoe Morio , Jumonji Hiromichi
Published: October 2005

Electrical characteristics of a lossless ceramic resonator with a fully covered electrode can be expressed by three basic parameters: clamped capacitance, electromechanical coupling factor, and the gravest resonant frequency or antiresonant frequency. Unified formulas are derived for various modes of vibration with longitudinal and transverse electric fields. The formulas are valid for a very wide range of frequency, but it is not easy to use them for calculation in most cases because of the transcendental functions involved. Hence, approximate formulas are derived that are simple and easy to calculate but accurate enough for practical uses. The accuracy of the approximation is far better than the accuracy of conventional lumped-constant equivalent-circuit representation. A novel method for determining three basic parameters of a ceramic resonator with transverse electric field is developed, based on the present approximate formulas. The method requires only the measurement of resonant frequencies, before and after the insertion of a series capacitance, and eliminates the need for both the measurement of antiresonant frequency and the measurement of low-frequency capacitance, which are required in a conventional practice.
Transverse Thickness Modes in BT-Cut Quartz Plates
Authors: Spencer W. J.
Published: October 2005

The frequency versus length-to-thickness ratios for the thickness/shear and thickness/twist modes in BT-cut quartz plates are given. The C44 thickness/shear frequency is calculated and this mode is identified in contoured circular BT plate by x-ray-diffraction topography. The electrode-length to plate-thickness ratios for suppressing the anharmonic overtones in both AT and BT plates as a function of electrode thickness are derived and compared with those measured on partially electroded quartz plates. The use of BT plates as singly resonant and coupled-mode resonators is discussed.
Far-Field Sound Radiation from Randomly Vibrating Structures
Authors: Greenspon Joshua E.
Published: October 2005

This paper presents general relationships for the cross-spectral density of the sound pressure radiated from a randomly vibrating structure. Simplified relationships for the mean-square far-field pressure are given for the case of low damping. A free-field Green's function is introduced to study the directivity of the radiation from cylindrical structures.
Application of the Mössbauer Method to Ear Vibrations
Authors: Gilad P. , Shtrikman S. , Hillman P. , Rubinstein M. , Eviatar A.
Published: October 2005

The Mössbauer effect has been applied to the measurements of phase and amplitude relations in the vibrations of the guinea pig ear in vivo induced by sound in the normal hearing range. Measurements were made on the umbo and on the incudostapedial joint. The relative phase was near zero throughout the measured frequency range of 250 cps-9 kc/sec, and the lever-ratio was nearly constant at a value of about 2.0.
On an Unusual Mode of Chanting by Certain Tibetan Lamas
Authors: Smith Huston , Stevens Kenneth N. , Tomlinson Raymond S.
Published: October 2005

In certain Tibetan monasteries, the lamas are trained to chant in a distinctive way, yielding the impression that a single lama is singing a chord. The acoustics of this unusual vocal performance are discussed, and its contribution to the religious life of the lamas assessed.
Relative Intelligibility of Different Transforms of Clipped Speech
Authors: Ainsworth W. A.
Published: October 2005

In a speech wave that has been subjected to infinite clipping, only the sequence of time intervals between zero crossings remains, and yet the result is fairly intelligible. If positive-going and negative-going zero crossings are signaled by pulses of either the same or opposite polarity, it is possible to distinguish the time intervals between adjacent zero crossings from those between alternate zero crossings (i.e., crossings in the same direction). It has been found that transforms that maintain some indication of the polarity of the zero crossings are the most intelligible, whereas those that make no distinction are the least intelligible. The transforms in which zero crossings of only one kind are signaled form an intermediate category. Neither the polarity of the pulses nor the polarity of the zero crossings has any great effect on the relative intelligibility. Using data obtained in an experiment measuring the intelligibility of clipped speech, a confusion matrix of the various phonemes was constructed. It was found that vowellike phonemes are less often confused than fricativelike ones.
Propagation of S-H Waves in Inhomogeneous Media
Authors: Ravindra Ravi
Published: October 2005

It is shown that the equations of motion and the boundary conditions for S-H waves in solids and for sound waves in fluids are equivalent for inhomogeneous media. Relevance of some of the published results for sound waves is discussed in connection with the problem of reflection of S-H waves from transition layers.
Mechanically Variable Acoustic Surface-Wave Delay Line with a Noncontacting Transducer
Authors: Wen C. P. , Mayo R. F. , Schnitzler P.
Published: October 2005

Initial experimental results on quartz crystal-surface elastic-wave delay lines at 19 Mc/sec have indicated that electromechanical transduction can be accomplished without physical contacts between a transducer circuit and the surface of the crystal. The distance between the transmitting and the receiving transducers and, therefore, the real time delay can be made mechanically variable. The insertion loss is increased by 3 dB when the distance between the transducer circuit and the surface of the crystal is increased to λs/2. The acoustic surface wavelength λs is approximately 0.007 in. at 19 Mc/sec.
Ray Path in a Linearly Moving, Inhomogeneous, Layered Ocean Model
Authors: Hayre H. S. , Tripathi I. D.
Published: October 2005

A three-layer model of the ocean is assumed, employing a combination of varying and constant speed of sound and velocity of water media in various layers. Both the slope and the ray path are calculated and plotted for this model.
Epstein Normal-Mode Model of a Surface Duct
Authors: Bucker H. P. , Morris Halcyon E.
Published: October 2005

Equations are given for the normal-mode calculation of the sound field in a surface duct. The velocity-depth profile is represented as 1/v2 (z) = A sech2(z/H) + B tanh (z/H) + D, a form first used by Epstein for calculating the reflection of radio waves from a transition layer. A comparison of calculated and experimental measurements of propagation loss shows good agreement between theory and experiment.
Random Efficiency of Second-Order Gradient Microphones
Authors: Bauer Benjamin B.
Published: October 2005

The random efficiency of the second-order Limaçon transducer family, ρ = [m + (1 − m) cosθ][n + (1 − n) cosθ], is computed and minimum random efficiency of 0.125 is determined to occur when either m or n is 35 and the other is 0.
Asymmetries in the Cumulative Probability Distributions of the Speech Waveform Instantaneous Amplitude
Authors: Williams G.
Published: October 2005

Asymmetries in the cumulative probability distribution of the speech waveform instantaneous amplitudes are studied. It is shown that the asymmetries which occur at large amplitude values are accompanied by a difference in the mean and median values of the distributions. Microphone characteristics and filtering reduce the gross asymmetry of the larynx fundamental waveform, resulting in a reduction in the over-all asymmetry.
Correction: Medium- and Far-Field Expressions for Velocity Potential of Circular Plane Piston [J. Acoust. Soc. Am. 39, 1142–1144 (1966)]
Authors: Williams A. O.
Published: October 2005

The article so titled was based upon a result of L. V. King's, which has been found to be in error. A correct treatment of the problem is described here. It substantiates the main approximation derived in the article and some-what improves upon it.
Vibrations of a Circular Plate Supported by a Concentric Ring of Arbitrary Radius
Authors: Bodine R. Y.
Published: October 2005

Natural frequencies are determined for the transverse vibrations of a circular plate that is simply supported by a concentric ring of arbitrary radius. Frequency coefficients are plotted for modes having 0, 1, 2, or 3 nodal diameters and 0, 1. 2, or 3 nodal circles. Comparison is made with similar vibrations of the fixed center plate, the free-edge plate, and the plate simply supported at the edge.
Resonance Conditions for an Elastically Connected Double-Plate System Due to a Cyclic Moving Load
Authors: Kessel P. G.
Published: October 2005

Resonance conditions are determined for a rectangular, elastically connected double-plate system subjected to a moving point load of sinusoidally varying magnitude that oscillates longitudinally along one of the plates about a fixed point. The analysis shows that there are an infinite number of load-movement frequencies that will excite a given principal frequency of the system for the mnth mode of vibration.
Sound Localization by Fishes
Authors: van Bergeijk Willem A.
Published: October 2005

Fishes have two sound-sensitive organ-systems—the lateral line, which is sensitive to the near-field water motions of a sound source, and the swimbladder-ear system, which is sensitive to pressure waves. Since the lateral line is spread out over the fish's body, spatially sampling the strong intensity gradient of the near-field motions, it should be possible for a fish to localize a source of motion with this system. The swimbladder, however, is a solitary organ that samples only one point in the far field. The fish, therefore, should not be able to localize a source of pressure waves with the swimbladder-ear system. Experimental evidence, though spotty, confirms these notions.
Sound Transmission through Rectangular Slots of Finite Depth between Reverberant Rooms
Authors: Sauter August , Soroka Walter W.
Published: October 2005

An approximate theoretical relationship has been developed for the transmission of sound between two reverberant rooms through a connecting rectangular slot of finite depth. The theory makes use of impedance functions of rigid weightless rectangular pistons and assumes plane-wave propagation through the slots. Slots having aspect ratios of 1, 2, 4 and 8, and depth of 12 in., were tested between two 1750-ft3 reverberation chambers. Three different slots for each aspect ratio were tested, and the slot dimensions were so chosen as to have the cross-sectional areas π/4, π, and 4π in.2 in each case, to compare with previously published results on circular apertures having these areas. Numerical solutions on a digital computer are compared with experimental results and the agreement is found to be excellent over the range of the parameter—wavenumber times equivalent radius of a circular section having the same area as the rectangular section—from 0.05 to 3.2.
Ultrasonic-Absorption and Sound-Speed Data for Nine Liquids at High Pressures
Authors: Hawley Stephen , Allegra John , Holton Gerald
Published: October 2005

Data for ultrasonic absorption and sound speed are given for water, methyl alcohol, ethyl alcohol, n-propyl alcohol, n-butyl alcohol, eugenol, carbon tetrachloride, n-hexane, and toluene, for pressures ranging up to about 5000 kg/cm2.
Pressure Dependence of the Ultrasonic Absorption in Toluene and Hexane
Authors: Allegra John , Hawley Stephen , Holton Gerald
Published: October 2005

Ultrasonic absorption and sound speed have been measured in toluene and n-hexane in the pressure range 1–10 000 kg/cm2 at 30°C. In these Kneser-type liquids, for which the absorption may be attributed to thermal relaxational processes as well as to the dilatational and shear viscosities, various contributions to the absorption can be resolved by making specific assumptions about the ratio of the dilatational and shear viscosities. An attempt has been made to relate the thermal contribution to relevant theory.
Line Admittance of Infinite Isotropic Fluid-Loaded Plates
Authors: Nayak P. Ranganath
Published: October 2005

The response of infinite isotropic plates submerged in a fluid and subject to spatially uniform temporally harmonic line forces and moments is obtained. The frequencies of the line loads range from f = 0 to f = fc, where fc is the coincidence frequency for plate waves. The power radiated into the fluid per unit length of support due to a normally incident plate wave is also obtained for (1) simple line supports, and (2) clamped supports. The effects of fluid loading on the radiated power are (1) to increase the force and moment reaction of a support to an incident plate wave, and (2) to decrease the power radiation from a line force or moment of given magnitude. The net effect of fluid loading is to decrease the radiated power, but neglect of the first effect would cause a considerable underestimation of the power radiated from supports, for f≪fc. Finally, the transmission of normally incident plate waves past simple line and clamped supports is investigated.
General Motion of Impact Dampers
Authors: Masri S. F.
Published: October 2005

The exact solution of the general steady-state response of a sinusoidally excited primary system provided with an impact damper is derived analytically by treating the motion of the system as a piecewise linear process. The asymptotically stable regions of the resulting multivalued solutions are determined. Experimental investigations using an electronic analog computer in addition to numerical studies on a digital computer are described, and it is shown that the predictions of the theory are verified. The effects of viscous damping, frequency ratio, mass ratio, coefficient of restitution, clearance ratio, and initial conditions on the response and stability of the system are discussed, and optimum response curves over a wide frequency band are presented. The findings of this study are significantly different, both quantitatively and qualitatively from those of a recent investigation of impact dampers.
Measurement of Power Flow in Uniform Beams and Plates
Authors: Noiseux D. U.
Published: October 2005

A novel technique is presented for measuring the vibrational intensity (power flow per unit width of cross section) in uniform plates and beams vibrating in flexure. The intensity is obtained as a vector at a measurement point. Measurements at many points yield the pattern of power flow. Experimental results of intensities in a very reverberant plate illustrate the measurement technique and are consistent with the loss factor of the plate.
Doppler Characteristics of a Sonar Signal Propagating through an Anisotropic Medium Whose Index of Refraction is a Function of Time
Authors: Broca Laurent A.
Published: October 2005

When a body is in motion through a water environment with a time-varying index of refraction, the returned sonar signal will contain three independent Doppler shifts, one caused by the purely geometrical relative motion of the sonar and the target, one by the gradient distribution, and one by the anisotropic characteristics of the sonic refractive medium along the propagation path.
Acoustic Characteristics of Woods at High Hydrostatic Pressure
Authors: Lastinger J. L.
Published: October 2005

The acoustic absorption and speed of sound in various kinds of water-saturated wood at three grain orientations have been measured in the frequency range 3–8 kHz at hydrostatic pressure to 10 000 psi. The measurements were made in a 6-ft-long 2-in.-i.d. acoustic-impedance pulse tube. Absorption is greatest for sound propagated parallel with or at 45° to the grain of the wood, and least for perpendicular propagation; the sound speed is greatest parallel with the grain and least at 90°. Generally, the measured change in acoustic characteristics with hydrostatic pressure is negligible.
Radiation Resistance of a Small Transducer at a Water Surface near Plane Boundaries
Authors: Stumpf F. B. , Lam Y. Y.
Published: October 2005

Experiments are described for the measurement of the radiation resistance for a small sonar transducer at an air-water surface in the presence of nearby plane boundaries in the water with various geometries. It is shown that a dipole-image model seems to explain the measurements.
Vertical Coherence of Shallow-Water Reverberation
Authors: Urick R. J. , Lund G. R.
Published: October 2005

During a field experiment in 200 ft of water off the west coast of Florida, the vertical coherence of the reverberation following a small explosive charge was measured by recording, and later correlating, the outputs of a string of vertically separated hydrophones. The reverberation coherence, in terms of the cross-correlation coefficient between hydrophone pairs, was found to increase with time after detonation, so as to indicate that the reverberation reaches the hydrophone string, within an ever-narrowing vertical angle, as time or range increases. The equivalent vertical angle of the reverberation was found to decrease with time or range and to lie in the range 5°–30° at frequencies between 200 and 8000 Hz. It is so small that only an extremely long vertical array can yield an appreciable array gain for active sonars operating in a background of shallow-water reverberation.
EARPHONE SYSTEM FOR HUMAN INFANTS
Authors: Peltzman Philip , Bass Alan , Manchester David
Published: October 2005

A condenser microphone-driver system has been designed specifically for use as an infant earphone. A simple economical negative feedback amplifier compensates for the distortion of the condenser microphone when used as an earphone. The physical properties and unique advantages of the insert ear tubes present no apparent discomfort to a sleeping or awake infant, afford a measure of sound pressure generated in the ear canal, and permit a wide latitude of head movement.
The Physics of Flow Noise
Authors: Haddle G. P. , Skudrzyk E. J.
Published: October 2005

The nearfield flow noise that is generated in the boundary layer of a vehicle in water turns out to be practically, independent of the kind of vehicle that generates the turbulence. Recorded levels depend on the size and shape of the recording hydrophone, even at very low frequencies when the linear dimensions of the hydrophone are small as compared to the convection wavelength of the turbulence. At high frequencies, because of their finite size, all hydrophones become nearfield insensitive and record the radiated noise. No significant difference was observed in the radiated-noise curve measured at a distance of about 100 ft from a rising buoyant unit, not even at frequencies as low as 150 Hz, whether the unit was of solid wood or had a thin metal shell. The radiation field depends on the second time derivative of the turbulent velocity fluctuations and, consequently, on the unsteadiness and intermittancy of the turbulence in the boundary layer. For a rotating cylinder, the measured radiation field levels approach those predicted by the recently improved Lighthill formula. For a ship, they are higher; for a buoyant unit, which is a small and a very unstable vehicle, the radiated noise becomes particularly great.
Sound Velocity and Absorption in Low-Pressure Gases Confined to Tubes of Circular Cross Section
Authors: Shields F. Douglas , Faughn Jerry
Published: October 2005

The propagation constant for sound waves propagated through gases confined to tubes is shown to be a function of the specific heat of the gas, a “Reynolds” number, a “Knudsen” number, and the momentum and energy accommodation coefficients of the surface. A numerical solution for the propagation constant agrees with room temperature velocity and absorption measurements in Ar and N2 assuming a momentum accommodation coefficient of 1 and an energy accommodation coefficient of 0.9. No effort was made to clean the tube-wall surface, and no difference could be detected in a stainless steel and a brass tube. The method offers considerable promise for measuring energy accommodation coefficients.
Dependence of the Cochlear Microphonics and the Summating Potential on the Endocochlear Potential
Authors: Honrubia Vicente , Ward Paul H.
Published: October 2005

The resting potential of the scala media (EP) in the first turn of the guinea pig's cochlea was altered by the application of currents. The EP as well as the cochlear microphonics (CM) and the summating potential (SP) were enhanced when the source electrode was in the scala media, whether the sink electrode was in the scala tympani or scala vestibuli. Using the scala media electrode as the sink for the current caused decreases in these potentials. When the EP change was sufficient to reverse the dc gradient across the reticular lamina, the CM reversed their polarity. A linear relationship exists between the changes in CM and EP. These results support the electromechanical theory of the production of microphonics.
Effect of Phase on the Timbre of Complex Tones
Authors: Plomp R. , Steeneken H. J. M.
Published: October 2005

Applying a digital computer both for signal generation and response processing, some experiments were carried out in which comparisons were made of the timbres of complex tones. The tones had equal loudness and pitch but different phase and amplitude patterns of the harmonics. The stimuli were presented successively in triads, and the subject's task was to select the most similar and most dissimilar pairs. The results were analyzed with Kruskal's multidimensional-scaling program. In general terms, the most important findings are: (1) the timbre difference between a tone consisting of only sine or cosine terms and a tone consisting of alternative sine and cosine terms represents the maximal possible effect of phase on timbre; (2) the maximal effect of phase on timbre is quantitatively smaller than the effect of changing the slope of the amplitude pattern by 2 dB/oct and is less for higher than for lower frequencies; (3) the effect of phase on timbre appears to be independent of the effect of amplitude pattern and of the loudness factor.
Perceptual and Physical Space of Vowel Sounds
Authors: Pols L. C. W. , van der Kamp L. J. Th. , Plomp R.
Published: October 2005

Experiments were carried out to investigate the correlation between the perceptual and physical space of 11 vowel sounds. The signals were single periods out of the constant vowel part of normally spoken words of the type h (vowel) t, generated continuously by computer. Pitch, loudness, onset, and duration were equalized. These signals were presented to 15 subjects in a triadic-comparison procedure, resulting in a cumulative similarity matrix. Multidimensional scaling (Kruskal) of this matrix resulted in a three-dimensional perceptual space with 1.6% stress. The signals were also analyzed physically with 13-oct band filters. Principal-components analysis of the decibel values per frequency band indicated that three dimensions accounted for 81.7% of the total variance. Matching the perceptual and the physical configurations to maximal congruence yielded an excellent result with correlation coefficients of 0.992, 0.971, and 0.742 along the corresponding dimensions. The formant frequencies and levels were correlated also with both configurations.
Spatial Averaging in a Diffuse Sound Field and the Equivalent Number of Independent Measurements
Authors: Schroeder M. R.
Published: October 2005

Consider two methods of spatial averaging of sound pressure squared in a diffuse sound field: (1) continuous averaging along a straight line of length N and (2) discrete averaging of Neq independent sampling points. Is there a unique equivalent number of independent sampling points Neq that gives the same reduction in variability as continuous averaging along a straight line of length X? The answer is that the equivalent number of independent sampling points depends upon whether sound power or sound level (in decibels or nepers) is used as a measure of variability. For sound power, the equivalent number of discrete independent sampling points equals approximately Neq (power) ≐ X/0.5λ, where X is the length of the (straight-line) averaging interval and λ is the wavelength. For sound level, the equivalent number of independent sampling points Neq (level) ≐ X/0.3λ. Thus, the concept of “equivalent number of independent sampling points” has to be applied with some caution.
Ultrasonic and Viscoelastic Relaxation in Bis[m-(m-phenoxy phenoxy) phenyl] Ether
Authors: Barlow A. J. , Lamb J. , Tasköprülü N. S.
Published: October 2005

The velocity of propagation and attenuation of longitudinal waves has been determined for a six-ring polyphenyl ether, bis[m-(m-phenoxy phenoxy) phenyl] ether. The viscosity, density, and shear relaxation properties of this liquid are known from previous measurements. It is found that the relaxing part K2 of the compressional modulus is equal to 43 times the limiting value of the shear modulus G∝, but the volume viscosity ηr is approximately 4 × 43 times the shear viscosity η. Within experimental error, the shape of the reduced relaxation curves for the components of the complex compressional modulus is the same as that found for the corresponding components of the complex shear modulus. This indicates that the shear and compressional relaxation processes have a common origin. These findings are compared with previously published results for associated liquids.
Decoupling of the Vector Wave Equation of Elasticity for Radially Heterogeneous Media
Authors: Singh Sarva Jit , Ben-Menahem Ari
Published: October 2005

The potential representation of the vector fields is employed to effect the decoupling of the vector wave equation of elasticity for radially heterogeneous isotropic media. Two types of decoupling are considered: decoupling for all values of the frequency and decoupling for high frequencies, which is useful in the ray-theory treatment. In the case of decoupling for all frequencies, the three constitutive parameters of the medium should satisfy a pair of nonlinear differential equations. For high-frequency decoupling, one of these equations becomes unnecessary. A few useful examples of the media that satisfy the conditions of decoupling are given.
Normal Compression and Radial Shear Waves Scattering at a Penny-Shaped Crack in an Elastic Solid
Authors: Sih G. C. , Loeber J. F.
Published: October 2005

The Hankel transform is used to obtain a complete solution for the dynamic stresses and displacements around a penny-shaped surface of discontinuity or crack embedded in an elastic solid, which is excited by normal compression and radial shear waves. By referring to a set of polar coordinates r1 and θ1 measured from the crack periphery, the dependence of the local stresses on r1 and θ1 is determined in closed elementary form, while the magnitude of these stresses, governed by the dynamic stress-intensity factors, is calculated numerically from a system of coupled Fredholm integral equations. As in the static case, the stresses possess the familiar inverse square-root singularity at the crack boundary. The stress-intensity factors, however, are found to depend on the incident wavelength and Poisson's ratio of the elastic solid. For certain values of the wavelengths, they are shown to be larger than those encountered in the theory of static elasticity.
Generation of Subharmonics of Order One-Half by Bubbles in a Sound Field
Authors: Eller Anthony , Flynn H. G.
Published: October 2005

Under proper conditions, bubbles driven by a sound field will pulsate periodically with a frequency equal to one-half the frequency of the sound field. This frequency component is the subharmonic of order one-half and is generated when the acoustic-pressure amplitude exceeds a threshold value. The threshold for subharmonic generation is calculated by means of a theory that relates the presence of the subharmonic to properties of Hill's equation. It is found that, for a given bubble, the threshold is a function of the driving frequency and is a minimum when the driving frequency is approximately twice the linear resonance frequency of the bubble. In addition, solutions of a set of nonlinear equations for the motion of the bubble wall, obtained on a computer, illustrate the growth of subharmonics and are used to determine the steady-state amplitude and phase of the subharmonic for a sequence of values of various parameters.