bluuebunny/crossref_metadata_2025 huggingface dataset:
Standard Calibration Hydrophone
Authors: Sims Claude C.
Published: September 2005

A new calibration standard hydrophone for use in the frequency range 5 cps to 150 kc is described. The active element is a lithium sulfate crystal on a tungsten backing plate. The free-field voltage sensitivity (end-of-cable) is −90±3 db re 1 v per μbar throughout most of the frequency range. The sensitivity is little affected by temperature changes in the range 1° to 25°C, and is not affected by hydrostatic pressure changes in the range 0 to 1000 psig. Directivity patterns are very nearly those to be expected from a 1-in. piston.
Rotational Relaxation in Nitrogen, Oxygen, and Air
Authors: Greenspan Martin
Published: September 2005

The speed and attenuation of sound at 11 Mc were measured in N2, O2, and dry air at various pressures between atmospheric and a few mm Hg. The rotational collision numbers were found to be: for N2, 5.26±0.05; for O2, 4.09±0.08; for air, 4.82±0.18.
Acoustic Field of a Circular Piston in the Near Zone
Authors: Quint Robert H.
Published: September 2005

By a power series expansion method an expression for the radiation potential of a circular piston mounted in an infinite baffle is derived. All points of the piston vibrate in phase and with equal amplitude in an infinite medium characterized by wavelength λ. The series expression is shown to be convergent at the surface of the piston (Z=0) when ka⩾20, and r100. For Z≫a, the Schoch expression is obtained.
Vowel Amplitude and Phonemic Stress in American English
Authors: Lehiste Ilse , Peterson Gordon E.
Published: September 2005

Many different instrumental techniques for deriving an energy property of the speech wave have been employed in communication studies. There is as yet, however, no satisfactory method of calculating the loudness of the various types of complex quasi-periodic sounds that appear as time functions in speech. This paper does not present a method of making such loudness calculations, but suggests that any such method would be inadequate for deriving physical correlates of accent or stress judgments about speech. The study reports volume indicator and instantaneous amplitude observations on sustained vowels produced under various conditions of speech effort, and on vowels produced in CNC syllables in a carrier phrase with stress held constant. The untested theory is proposed that the perception of linguistic stress is based upon judgments of the physiological effort involved in producing vowels. The relative amplitude and spectrum of the vowel provide the chief basis for judgment of the physiological effort.
Study of Temperature Variation of Ultrasonic Velocities in Some Organic Liquids by Modified Fixed-Path Interferometer Method
Authors: Rao K. Subba , Rao B. Ramachandra
Published: September 2005

A simple, rapid, and accurate method of determining temperature coefficient of ultrasonic velocity in liquids is presented. The method is based on a modification of the fixed-path double-crystal interferometer. Temperature variation of ultrasonic velocity in a few organic liquids have been studied by employing this method.
Finite-Amplitude Propagation Effect on Shock-Wave Travel Times from Explosions at High Altitudes
Authors: Otterman Joseph
Published: September 2005

In this paper a method is described for calculating the effect of the finite-amplitude propagation on the travel times of pressure waves from explosions at high altitudes to the ground. Numerical results are presented for explosions of 2-lb and 4-lb H. E. charges at altitudes ranging from 15 to 95 km. Vertical propagation is assumed in the calculations. This work has been carried out in order to improve the systematic accuracy of the rocket grenade experiment for upper atmosphere temperature and winds. The significance of the finite-amplitude propagation in this experiment is discussed.
Latency of Action Potentials in the Cochlea of the Guinea Pig
Authors: Deatherage Bruce H. , Eldredge Donald H. , Davis Hallowell
Published: September 2005

The latency of the well-synchronized whole-nerve action potential (AP) in the cochlea of the guinea pig includes both neural and traveling-wave delays. The latency varies with the intensity and with the frequency of the acoustic stimulus. Selective local interference with the response was produced by (1) selective masking, (2) local fatigue of sensory elements, and (3) local injection of drugs. Such interference the basal turn prolonged the latency of the AP response. Low-frequency tones can reduce the N1 response to click stimuli without changing the modal latency. Apparently nearly all of the well-synchronized AP is due to neurons that arise in the first turn of the cochlea, regardless of the frequency of stimulation. The traveling-wave delay appears as a significant component of latency only in the smaller AP responses that remain after the impulses arising in the first turn are suppressed. Information about the time of onset of an acoustic signal can be delivered to the central nervous system primarily by the best-synchronized or modal portion of the AP response.
Search for Physical Correlates to Psychological Dimensions of Sounds
Authors: Solomon Lawrence N.
Published: September 2005

Twenty passive sonar recordings were ranked by 50 subjects in terms of their aurally perceived (psychological) characteristics on seven different dimensions. Correlations were run between octave band sound pressure level measurements of the sounds and their rank orders on the seven psychological dimensions. Meaningful relationships were found between ranks on certain psychological dimensions and energy concentration within certain octave bands.

Also, an analysis was made of the manner in which the twenty sounds clustered within the space defined by the seven psychological dimensions. Analyses of these sound clusters revealed that the rhythmic beat pattern of the stimulus is a principal attribute upon which sonar men base their judgments of “similarity.”
Age and Sex Differences in Pure-Tone Thresholds
Authors: Corso John F.
Published: September 2005

In recent years there has been an increased emphasis on medicolegal problems involving the assessment of hearing loss due to noise exposure. One of the attendant difficulties, however, has been the problem of separating the factors of noise exposure and of age as contributors to hearing disabilities. The present study was performed to determine the normal thresholds of hearing for pure tones for an age-stratified sample of subjects drawn from a population exposed to minimal levels of industrial noise. Audiometric measurements from 250 to 8000 cps were made on a total of 500 subjects divided into four age groups: 18 to 24, 26 to 32, 34 to 40, and 43 to 49 years, inclusive. The results of this study indicate that, in general, only minor differences (less than 5 db) exist between the average thresholds of right and left ears, but that women have more sensitive hearing than men and show less intersubject variability. This sex difference is independent of age and is more marked at the higher frequencies. For both men and women, there is a decrease in hearing sensitivity with increasing age and a progressive spreading of the loss from the higher to the lower frequencies. Men are more affected than women, with the hearing loss occurring at an earlier age and producing a greater degree of auditory impairment. The threshold curves of the present study are considered to yield a more valid estimate of the “pure” effects of age on hearing than previously available. It is recommended that future audiometric standards be specified independently for men and for women according to particular age levels.
Method of Obtaining Amplitude and Phase Spectra of a Transient Function Using Graphical Input Data
Authors: Remillard Wilfred J.
Published: September 2005

Both amplitude and phase spectra are needed to characterize transient functions completely. Analysis shows how these spectra can be obtained from the envelopes of the line spectra of the even and odd parts of a transient function made to recur in time. Instrumentation is described for the convenient determination of these line spectra.
Absorption of Sound by a Strip of Absorptive Material in a Diffuse Sound Field
Authors: Northwood T. D. , Grisaru M. T. , Medcof M. A.
Published: September 2005

The random incidence sound absorption coefficient is calculated for a narrow strip of absorbing material set in an otherwise reflecting plane. The assumptions made are that the material is of the locally reacting type, with a real normal admittance. The effect of an imaginary component of admittance is discussed qualitatively.

The results show the increase in absorption coefficient that occurs at small widths due to diffraction. Consideration is also given to the absorption of rectangular patches having both dimensions in the diffraction range. The standard reverberation room measurement of sound absorption is examined.
Propagation of Traveling Waves in a Circular Cylinder Having Hexagonal Elastic Symmetry
Authors: Einspruch Norman G. , Truell Rohn
Published: September 2005

The problem of propagation of traveling waves in a right circular cylinder having hexagonal elastic symmetry is considered here. Exact expressions for the displacements produced by both the compressional and torsional modes are obtained. A conclusion of importance in ultrasonic methods is the result that the compressional and torsional modes propagate independently without coupling either through the equations of motion or the boundary conditions. A condition relating the frequency and wave number of the torsional wave is derived.
Intracardiac Acoustics
Authors: Wallace John D. , Brown James R. , Lewis David H. , Deitz George W. , Ertugrul Ali
Published: September 2005

The operation of the human heart together with the sounds resulting from normal operation are discussed. Examples of the diagnostic, intracardiac sounds due to several of the common congenital lesions are cited and analyzed. Transmission and magnitude of heart sounds within the heart have been measured and are reported.
Experimental Study of the Propagation of Sound over Ground
Authors: Wiener Francis M. , Keast David N.
Published: September 2005

The attenuation of sound propagated out-of-doors is conveniently separated into attenuation due to spherical divergence and excess attenuation due to atmospheric and terrain effects. This excess attenuation is principally caused by sound absorption in the air, the refractive effects of temperature and wind gradients, by turbulence and the effects of terrain and ground cover. To investigate these effects the propagation of sound over open, level ground, through dense evergreen forests, and between hilltops was studied experimentally in the frequency range between about 300 cps and 5000 cps. Extensive micrometeorological instrumentation was utilized to measure and record the relevant micrometeorological parameters simultaneously with the acoustic data for a wide variety of weather conditions. Data on the attenuation of the mean received sound pressure level as well as on the fluctuations about the mean were obtained and correlated with the state of the atmosphere.

Over open level terrain, the excess attenuation upwind was found to exceed that for downwind propagation by as much as 25–30 db for source and receiver heights of 12 and 5 ft, respectively. Temperature and wind gradients near the ground-air interface largely account for this difference. In hilltop-to-hilltop propagation, wind direction is of secondary importance, and in dense woods absorption and scattering control. Empirical functions were derived for the purpose of estimating the mean excess attenuation as a function of frequency and distance, for a given set of micrometeorological conditions. These charts have been found useful in many practical problems involving the propagation of sound over open level ground.
Thickness-Shear Vibrations of Circular Bars
Authors: Baltrukonis J. H. , Gottenberg W. G.
Published: September 2005

Exact general solutions of the three-dimensional elasticity equations of motion in polar cylindrical coordinates are obtained for axisymmetric and antisymmetric thickness-shear vibrations. These solutions are applied in solving five solid and hollow circular bar problems. Natural frequencies are tabulated.
Relation between Hearing Threshold and Duration for Tone Pulses
Authors: Plomp R. , Bouman M. A.
Published: September 2005

This paper deals with some measurements concerning the threshold versus duration for tone pulses. A new hypothesis introduced: Switching on a tone pulse of intensity I results in an effect s somewhere in the hearing pathway, that approaches its final value asymptotically according to an exponential function; this final value is proportional to I; perception occurs when s exceeds a critical value s0. The experiments show that this hypothesis gives a better description than the hypotheses thus far used. The time constant varies from ca 375 msec at 250 cps to ca 150 msec at 8000 cps. For short pulse durations the data deviate from the hypothesis. This deviation can be explained by the assumption that energy integration around each frequency is restricted to a fixed band width. A formula is derived which gives a correction to the mentioned relationship for short durations. In this way the band width at the different test frequencies could be determined. The general course of this band width as a function of frequency agrees with the “Kopplungsbreite” after Gässler.
Operating Characteristics Determined by Binary Decisions and by Ratings
Authors: Egan James , Schulman Arthur I. , Greenberg Gordon Z.
Published: September 2005

With the theory of signal detectability as a framework, two psychophysical experiments were conducted in which each observation interval was well defined for the listener. Each interval contained noise, and it either did or did not (p=0.5) contain a signal (1000 cps, 0.5 sec in duration). In separate sessions of the first experiment, either the listener gave a yes-no decision or he responded with a rating (1–4) after each observation interval. Operating characteristics were obtained with E/N0 equal to 15.8. It is clear from the data that the trained listener can perform as well when he adopts the multiple criteria necessary for the rating method as when he adopts the single criterion required by the binary-decision procedure. In the second experiment, only the rating method was used to determine the relation between d′ and E/N0. The resulting function, for d′ ⩽ 3.0, approximates straight line which passes through the origin and which has nearly the same slope as that obtained in other laboratories.
Influence of Fluid Motion Past a Plane Boundary on Sound Reflection, Absorption, and Transmission
Authors: Ingard Uno
Published: September 2005

It is shown that the effect of fluid motion past a plane boundary on the reflection and absorption of sound is equivalent to an increase of the normal acoustic impedance of the boundary by a factor (1 + M sinφ), where φ is the angle of incidence of the sound wave, and M is the Mach number of the flow velocity component in the incidence reflection plane of the wave. Similarly, the acoustic energy flux perpendicular to the boundary and the flow is shown to be increased by the same factor. Reflection and transmission coefficients of a thin solid interface between a fluid in motion and one at rest are given. Furthermore, some comments on the problem of transmission in duets are given. For propagation between two plane parallel boundaries with the same acoustic admittance, we find, for sufficiently small values of the admittance, that the sound pressure attenuation constant of the fundamental mode is modified approximately by the factors (1 + M)−2 and (1 − M)−2 for downstream and upstream propagation, where M is the flow Mach number.
Response of Plates to a Decaying and Convecting Random Pressure Field
Authors: Dyer Ira
Published: September 2005

Following the methods of Lyon, an analysis of the vibratory response of a plate to a random pressure field is given. The pressure correlation of the random field is assumed to have a scale small compared to the plate size, to decay exponentially, and to convect with constant speed over the plate. Two eases are considered, one in which the convection speed is much less than the speed of free flexural waves in the plate, the other in which the convection speed is the same order as the flexural wave speed. The mean square plate displacement is shown to be relatively independent of convection for speeds much less than the flexural wave speed, and to increase significantly for speeds in the order of the flexural wave speed. It is shown that damping is usually, but not always, an effective means of vibration reduction. In the case of convection speeds much smaller than the flexural speed, the use of hysteretic damping for reduction of the displacement response is shown to be limited by the decay of the assumed random pressure field.
Mutual Radiation Impedance of Sources on a Sphere
Authors: Sherman Charles H.
Published: September 2005

Expressions for the mutual radiation impedance coefficient are derived in the cases of uniformly vibrating circular and rectangular acoustic sources on a rigid spherical baffle. Numerical results for circular sources on a sphere are given as a function of the source separation for several values of ka (a is the radius of the sphere and k is the wave number). The interaction between circular sources on a large sphere and on a plane is compared numerically.
Damping of Flexural Waves by a Constrained Viscoelastic Layer
Authors: Kerwin Edward M.
Published: September 2005

For a number of years it has been known that flexural vibrations in a plate can be damped by the application of a layer of damping (viscoelastic) material that is in turn constrained by a backing layer or foil. A common example is the damping tape currently used in aircraft.

This paper presents a quantitative analysis of the damping effectiveness of such a constrained layer. As in the work of H. Oberst the damping is characterized by the loss factor η, which is the normalized imaginary part of the complex bending stiffness of the damped plate.

The calculated damping factor depends on the wavelength of bending waves in the damped plate, and on the thicknesses and elastic moduli of the plate, the damping layer, and the constraining layer. A complex shear modulus is assigned to the damping layer, where all of the energy dissipation is assumed to take place.

Damping factors have been determined experimentally on laboratory test bars for a number of constrained-damping-layer applications for frequencies from about 100 to 4000 cps over a range of temperatures. Gratifying agreement with calculated damping has been found for variations in frequency, temperature, and damped-bar geometry.
Resonance Absorption and Molecular Crystals. II. Benzene
Authors: Liebermann Leonard
Published: September 2005

Thermal oscillations in molecular solids are of two distinct classes: lattice vibrations and atomic vibrations within each molecule. These two vibrational modes can overlap in frequency and “resonate.” This resonance leads to lengthy relaxation times manifested as unusually high acoustic absorption, a phenomenon termed resonance absorption. In order to study resonance absorption in solid benzene a method was developed for growing single benzene crystals of average linear dimension, 10 cm. At the acoustical frequency 10 mc, absorption in single benzene crystals is found to be 0.24 cm−1; at 6.4 mc the value is 0.09 cm−1. This excessively high absorption (104 higher than in crystalline quartz) was quantitatively predicted from available molecular constants by a theory given previously. A partial list of compounds is given in which resonance absorption is predicted to be the dominant absorption mechanism.
Splashes as Sources of Sound in Liquids
Authors: Franz G. J.
Published: September 2005

The mechanisms of sound production by the splashes made by the gas-to-liquid entry of objects are discussed. The sound from the splash is considered to be associated with acoustic multipoles of all orders, the main ones being simple sources, dipoles, and quadrupoles. The orders of the multipoles that predominate during the various phases of the splash are estimated from the flow and boundary conditions. The sounds radiated into the water by the low-velocity vertical entry of single water droplets, sprays of water droplets, and various other objects, such as spheres, cones, and wedges, have been measured and found to have the characteristics of acoustic dipoles. The extensive experimental data on the spectrum of the underwater sound from the splashes of droplets and sprays and the scaling laws for dipoles are used to estimate the spectrum levels of the underwater sound from the splashing of rain on the surface of a sea in terms of the rate of rainfall.
Additivity of Different Types of Masking
Authors: Bilger Robert C.
Published: September 2005

Two experiments were carried out to determine how masking for frequencies either above or below one band of noise combine with the critical-band type masking produced by a second band of noise. The results of both experiments indicate that at moderately high levels the combination of critical-band masking with another type of masking results in a 6-db increase in masking. The implications of this result are discussed.
Identification of Elementary Auditory Displays and the Method of Recognition Memory
Authors: Pollack Irwin
Published: September 2005

The “method of recognition memory” is considered as a procedure which permits the examination of the identification of elementary auditory displays without requiring the assignment of arbitrary designations to the displays. The procedure is described and illustrative results are presented.
Scattering of High Frequency Sound Waves in Polycrystalline Materials. II
Authors: Bhatia A. B. , Moore R. A.
Published: September 2005

The calculations of a previous paper, which were based on a simplification in that the effective elastic properties of each grain were described by just Lamé's two elastic constants, are generalized to take into account the fact that an elastically anisotropic medium has actually several independent elastic constants. The final expressions for the attenuation coefficient of shear and dilatational waves exhibit qualitatively similar features as the corresponding expressions of the previous paper but differ quantitatively from them.
On the Diffusion of Sound Waves in a Turbulent Atmosphere
Authors: Lyon Richard H.
Published: September 2005

The directional and frequency diffusion of a plane monochromatic sound wave in statistically homogeneous, isotropic, and stationary turbulence is analyzed theoretically. The treatment is based on the diffusion equation for the energy density of sound waves, using the scattering cross section derived by Kraichnan for the type of turbulence assumed here.

A form for the frequency wave number spectrum of the turbulence is adopted which contains some pertinent parameters of the flow and is adapted to ease of calculation. It is expected that the assumed spectrum is unrealistic at larger wave numbers. A new approach to the evaluation of the characteristic period of the flow is suggested. This spectrum is then related to the scattering cross section.

Finally, a diffusion equation is derived as a small-angle scattering approximation to the rigorous transport equation. The rate of spread of the incident wave in frequency and direction is calculated as well as the power spectrum and autocorrelation functions for the wave.
Bending Wave Propagation in Multilayer Plates
Authors: Kurtze Günther
Published: September 2005

Flexural wave propagation and damping in multilayer plates is treated theoretically with use of impedance techniques. These techniques yield equivalent electrical circuits whose behavior is determined either by standard circuit analyses or by analog electrical measurements. The properties of two types of multilayer damping treatments are investigated detail. The first type is a two-plate system enclosing a viscous liquid. The viscous liquid may also contain pressure-release partitions. The second type investigated consists of a layer of an air-filled porous material placed between a plate to be damped and an array of masses. Flexural wave measurements carried out on these multiple plates are shown to be in good agreement with calculations. It is shown that the viscous liquid layer and the porous layer may have high loss tangents in particular frequency ranges. With the use of the impedance techniques, a comparison made between the damping treatments studied and two other damping treatments that have Been investigated earlier by Oberst and Kerwin.
Formulas for the Computation of Sound Speed in Sea Water
Authors: Mackenzie K. V.
Published: September 2005

Equations are presented for the computation of sound speed that are designed to agree with Kuwahara's tables. These are in general use for the mass reduction of oceanographic data. The equations give the temperature, salinity, depth, and latitude dependence and the interaction effects due to the simultaneous variation of temperature, salinity, and depth. Some in situ measurements utilizing the bathyscaph are presented.
Noise Surveys of Cocktail Parties
Authors: Legget R. F. , Northwood T. D.
Published: September 2005

This paper discusses and enlarges on a recent theoretical paper by W.R. MacLean on the acoustics of cocktail parties. The discussion is supported by experimental evidence accumulated during the past two years. MacLean's analysis suggests that there is a critical density of participants above which a “quiet” cocktail party becomes abruptly “noisy.” It would appear that one might actually plan a quiet or noisy party as required (assuming control over the number of participants). Unfortunately the cases studied experimentally do not show this quiet-noisy transition, and it is believed that factors not considered in the theory result in a blurring of the distinction. Indications are that there is a gradual increase in sound level to a saturation value that is independent of the properties of the room, the beverages served, and the number of participants. There is, however, dependence on the sex of the participants.
Study of Acoustic Propagation in a Two-Layered Model
Authors: Eby R. K. , Williams A. O. , Ryan R. P. , Tamarkin Paul
Published: September 2005

To study acoustic propagation in shallow water without the idealization of conventional theory or the many unknowns in field trials, a model with known realistic parameters is used. A water layer 0.5 to 2 cm deep overlies a 2-in. slab of Hycar rubber with greater density and sound speed. With frequencies from 55 to 600 kc, a small probe in the water allows measurements of phase and group velocities, vertical pressure distributions, mode interferences, and attenuation coefficients. Theoretical predictions about the effects of compressional absorption and shear waves in the bottom, and of sloping bottoms, are supported. An analysis of the additional attenuation caused by rough surfaces is made by spreading small metal spheres on the bottom. This attenuation is proportional to area density of the spheres, the free-field scattering cross section of a sphere, and the acoustic intensity at the depth of the spheres. An additional factor is the fraction g of scattered power actually lost; g correlates empirically with the ratios water depth to sphere radius and sphere radius to acoustic wavelength. A phenomenological theory ties these results together.
Psychoacoustics and Detection Theory
Authors: Green David M.
Published: September 2005

This paper presents a fairly complete review of detection theory as it is applied to certain psychoacoustic data. Detection theory is treated as a combination of two theoretical structures: decision theory and the concept of ideal observer. The paper discusses how statistical decision theory has been used to analyze the auditory threshold process. By treating the threshold process as an instance of hypothesis testing, two determinants of the process are recognized: (1) the detectability of the signal and (2) the criterion level of the observer. The theory provides a technic of analysis which allows one to obtain a quantitative estimate of both factors. The measure of signal detectability appears to be independent of the psychophysical procedure when the physical parameters of signal and noise are held constant. The concept of ideal observer is reviewed with special emphasis on the assumptions of the derivation. The usefulness of this concept is illustrated by considering the shape of the psychophysical function—the function relating the detectability of the signal to its intensity. A rather general model based on the concept of signal uncertainty is presented which attempts to explain this relationship.
Equation for the Speed of Sound in Sea Water
Authors: Wilson Wayne D.
Published: September 2005

An equation is given for the speed of sound in sea water. The experimental data used to determine this equation were obtained in the temperature, pressure, and salinity ranges −4°C <T <30°C, 1 kg/cm2 <P <1000 kg/cm2, and 0‰ <S <3‰. The standard deviation of the experimental data was found to be 0.30 m/sec.
Empirical Study of the Effect of Diffraction on Velocity of Propagation of High-Frequency Ultrasonic Waves
Authors: McSkimin H. J.
Published: September 2005

The effect of diffraction in increasing the velocity of propagation over the plane wave value is determined experimentally by phase comparison of reflected longitudinal waves in fused silica blocks. It is shown that the parameters of transducer diameter, path length traveled, and frequency can usually be adjusted to keep the fractional excess velocity under 0.02% for measurements in the 20–100-Mc range. This consideration is of particular importance in connection with precision measurement of elastic moduli.
Subharmonics and Plate Tap Tones in Violin Acoustics
Authors: Hutchins Carleen M. , Hopping Alvin S. , Saunders Frederick A.
Published: September 2005

From the study of subharmonic series found in the violin and related instruments, it is evident that the quality and loudness of the instruments depend on the pitch and variety of the subharmonic series, and on the characteristics of the wood and the fashioning of the top and back plates. Details are given on the nature of subharmonic series and their presence as observed in several methods of testing. The single air tone, heretofore reported, is shown by more detailed tests to consist frequently of two or more closely related peaks. Observations made in a series of experiments carried on during the construction of 35 violins, violas, and cellos indicate a method of controlling tone quality and volume of the completed instrument by means of the tap tones and the acoustic properties of the free plates. Experimental equipment which makes these findings possible is described in detail. With this concept of subharmonic series and the techniques described, a large field for experimental evaluation of string instruments may well be opened up.
Frequency Response of a Nonlinear Stretched String
Authors: Oplinger Donald W.
Published: September 2005

The problem of the forced vibration of an elastic string with variable tension is considered. All equation of motion is given for the case of low amplitude motion, but for strings of high modulus for which it is shown that tension variations are an important source of nonlinearity. An exact solution is obtained by assuming as a driving function a Jacobean elliptic function of the cosine type. Tension variations and amplitude are calculated as functions of frequency. Experimental results are presented and compared with the theory.
Electromagnetic Analogy to Sound Propagation in Moving Media
Authors: Kraichnan Robert H.
Published: September 2005

An analogy is developed between the paths of sound rays in fluids undergoing shear flow and electron trajectories in magnetic fields. If the Mach number of the flow is small, and the characteristic eddy size large compared to the sound wavelength, the ray paths coincide with electron trajectories in a magnetic field everywhere parallel and proportional to the vorticity vector. The ratio of the magnitude of the magnetic field to the electron momentum is determined by eH/Pc0 = ψ/c where H = magnetic field, P = electron momentum, e = electron charge, c0, c = velocities of light and sound, ψ = vorticity. Mathematically the analogy is implied by the similarity between the eikonal equation for the sound rays and the Hamilton-Jacobi equation for the electrons. Simple illustrations of the correspondence are given.
Pressure Dependence of Sound Propagation in the Primary Alcohols
Authors: Carnevale E. H. , Litovitz T. A.
Published: September 2005

Measurements of sound absorption and velocity were made on the ethyl, methyl, n-propyl, and n-butyl alcohols up to a pressure of 2000 kg/cm2. The results showed that both the shear and compressional viscosities of these liquids increased as the pressure increased, the pressure dependence of the compressional viscosity being the smaller of the two. Measurements of the temperature dependence of the absorption in n-butyl alcohol at 2000 kg/cm2 showed that no detectable difference in the activation energies for the two viscous processes was caused by the high pressure.

It was found that the two-state structural relaxation theory proposed by Hall to explain sound absorption in water is inadequate to explain the pressure dependence of sound absorption of the alcohols.
Calibration of Test Records by Interference Patterns
Authors: Bauer B. B.
Published: September 2005

This investigation stemmed from an attempt to explain the nature of the dispersion which occurs when a beam of light is reflected from a test record. Examination through color filters revealed the existence of two distinct patterns of lines which the author has termed the A- and B-lines. A-lines are identified with the frequency and B-lines with the amplitude of the recorded sound. B-line patterns can readily be related to the modulation velocity of the record and they lead to a determination of the recorded velocity characteristic of a test record. Characteristics by conventional light patterns are found to be in error owing to the diffraction of light at the edges of the pattern. This error is ascertained by subtracting the modulation velocity by B-line patterns from that determined by conventional light-pattern techniques, and it is found to be of the order of magnitude of the calculated diffraction error from assumed triangular wavelets. Calibrations of representative test records by B-line patterns are in much better agreement than those obtained by conventional light patterns with the calibrations by the variable turntable technique, especially when the latter are corrected for the elastic deformation of the grooves owing to the pickup load.
Relaxations in the Attenuation of Single Crystal Lead at Low Temperatures and Their Relation to Dislocation Theory
Authors: Mason W. P.
Published: September 2005

Measurements of the attenuations of face-centered metals by Bordoni have shown attenuation peaks at low temperatures. By using the measurements of Bömmel on single crystal lead it can be verified that this is a relaxation and values can be obtained for activation energies and frequency terms. It is shown that the measured results correlate well with a relaxation due to the displacement of a dislocation from one atomic line to an adjacent one against the limiting shearing stress of the crystal. The limiting shearing stress measured for four face-centered metals is in good agreement with theoretical calculations of Cottrell.

A higher temperature loss is also measured which increases exponentially with the temperature. It is shown that this term is due to breakaway of the dislocation from its impurity pinning points due to thermal agitation. This breakaway abstracts energy from the vibration and produces a loss independent of the frequency but increasing with temperature since more breakaways occur at higher temperatures. The activation energy of breakaways correlates well with the binding energy of impurity atoms.
Microacoustic Interferometer Using 30-Mc Pulses
Authors: McConnell R. A. , Mruk W. F.
Published: September 2005

In the described instrument ten-microsecond, 30-Mc carrier pulses reflected from a resonant layer allow a theoretical precision of 0.1 percent in making velocity determinations while using less than 0.1 cc of test liquid. By the same technique, ultrasonic absorption can be measured in highly dissipative liquids using layers about 0.1 mm thick. Water velocities observed at 30 Mc are presented along with values by others in the range of 0° to 93°C. V = 1554−0.0305(68.4−T)2 is proposed as the best empirical parabola to accommodate the available data, and an additional cubic correction formula is suggested.
On the Diffraction of Multipole Fields by a Semi-Infinite Rigid Wedge
Authors: Yildiz M. , Mawardi O. K.
Published: September 2005

A general expression has been derived for the evaluation of the pressure distribution, on the surface of a semi-infinite rigid wedge, due to a multipole point source. The derivation makes use of a Green's function constructed by means of spectral representations. The special cases of dipole and quadripole fields are worked out in detail.
Ultrasonic Velocities in Polarized Barium Titanate Ceramics
Authors: Huntington H. B. , Southwick R. D.
Published: September 2005

Measurements have been made of the ultrasonic velocities in polarized barium titanate ceramic blocks for both compressional and transverse waves, parallel and perpendicular to the axis of polarization. Some variation in compressional velocity with the degree of binding was evident. The largest variation between the velocities for transverse waves causing shear amounted to nearly 12 percent and proved to be accounted for by electromechanical coupling. The compressional velocity parallel to the axis of polarization ran some four percent higher than that at right angles. Here again it appeared that the effect was caused principally by differences in electrical boundary conditions and that the constant field elastic constants varied only slightly with polarization.
Improvements in the Sing-Around Technique for Ultrasonic Velocity Measurements
Authors: Forgacs R. L.
Published: September 2005

A highly sensitive sing-around system was developed for ultrasonic velocity measurements in solids. In the developed system, a selected cycle of a selected echo is gated out, to retrigger the transmitter. Highly stable circuitry is employed. The timing system incorporates two modified commercial electronic counters and associated circuitry to maximize stability and detection sensitivity. Environmentally induced sample velocity changes of the order one part in 107 may be detected, provided that the accompanying attenuation change is negligible, or that steps taken to compensate for ultrasonic attenuation changes by adjusting electronic attenuation, produce phase shifts which are known to sufficient accuracy.
Ultrasonic Attenuation Unit and Its Use in Measuring Attenuation in Alkali Halides
Authors: Chick Bruce , Anderson George , Truell Rohn
Published: September 2005

An instrument for measurement of ultrasonic attenuation and velocity in the frequency range from 5–200 mc/sec is described. The unit incorporates pulsed rf oscillator, superheterodyne receiver, exponential wave-form generator, precision time delay generator (useful in velocity measurements), CRT display circuits, and appropriate synchronization circuits. Ultrasonic attenuation measurements made in single crystals of NaCl and KCl during deformation and recovery at several temperatures are reported here.
Reflection of Sound from Coastal Bottoms
Authors: Mackenzie K. V.
Published: September 2005

The theory is discussed for the reflection of sound from flat and uniform fluid bottoms. Experimental 1-kc data obtained over three typical bottoms are presented for a range of grazing angles of incidence from 12° to 90° Experimental data are presented for normal incidence over several bottoms at frequencies of 4, 7.5, and 16 kc. The experimental data are compared with the available theories and the conclusion is reached that the Rayleigh theory modified by assuming complex velocity for the bottom gives the best agreement and that the agreement is best when the bottom attenuation is assumed to vary as the first or higher power of the frequency.
Temporary Threshold Shift in a Changing Noise Level
Authors: Ward W. Dixon , Glorig Aram , Selters Weldon
Published: September 2005

When an individual is exposed first to a high-level noise H for a time T and then to one of lower level L for time t, his temporary threshold shift (TTS) is equal to the numerical sum of (1) the TTS in db that would be produced by level L acting over a period of time T+t, and (2) the TTS in db that would remain after t min of recovery in quiet from TTSD, where TTSD is the difference between (a) the TTS at the end of the T-min exposure to H and (b) the TTS that would have been produced by T min of exposure to L. It appears that this result rules out any simple explanation of TTS.
Sinusoidal Pressure Generator with Wide Amplitude and Frequency Ranges
Authors: Perls T. A. , Miles D. O. , Wilner L. B.
Published: September 2005

Design considerations are given for a sinusoidal pressure generator (SPG capable of providing sinusoidal pressures up to 26 atmos peak to peak, proportional to input voltage to within 5% over the frequency range from 0 to 10 000 cps. The pressure is generated in a fluid contained in a relatively rigid metal enclosure, by means of a stack of 24 disks of a piezoelectric ceramic, connected electrically in parallel, and arranged so that their displacements add. Several applications of the SPG are discussed including several types of evaluation tests for pressure gauges, evaluation of electromechanical drivers, tests of piezoelectric materials near zero frequency, and study of frequency-dependent effects in liquids. Preliminary relaxation data are shown for two associated liquids, diphenyl metachloride (Aroclor No. 1260) and glycerol.
Vibration of a Square Plate Point Supported at Midpoints of Sides
Authors: Cox Hugh L.
Published: September 2005

An approximate solution is presented for the fundamental frequency of flexural vibration of a uniform elastic square plate that is point supported at the midpoints of the sides; otherwise, the boundaries of the plate are free. The solutions are valid for plates which have a value of Poisson's ratio of 0.3.
The Measurement of Loudness
Authors: Stevens S. S.
Published: September 2005

This paper reviews the available evidence (published and unpublished) on the relation between loudness and stimulus intensity. The evidence suggests that for the typical listener the loudness L of a 1000-cycle tone can be approximated by a power function of intensity I, of which the exponent is log102. The equation is: L = kI0.3. Intensity here is assumed to be proportional to the square of the sound pressure.

In terms of sones, where 1 sone is the loudness produced by a tone at 40 db above the standard reference level, the equation for loudness L as a function of the number of decibels N becomes: logL=0.03N−1.2.

Otherwise said, a loudness ratio of 2:1 is produced by a pair of stimuli that differ by 10 db, and this relation appears to hold over the entire range of audible intensities.

At low levels of intensity, the loudness of white noise grows more rapidly than the loudness of a 1000-cycle tone, but above the level of approximately 50 db the two loudnesses remain more nearly proportional. The suggestion is made that for all levels greater than 50 db the loudness of continuous noises may be calculated from the equation: logL=0.03N+S, where S is a spectrum parameter to be determined empirically.
Human Skin Perception of Traveling Waves Similar to Those on the Cochlea
Authors: v. Békésy G.
Published: September 2005

The membrane of a dimensional model of the mechanical parts of the human cochlea (30 cm in over-all length) showed under stroboscopic illumination traveling waves similar to those on the cochlea and a flat maximum of vibration which shifted from one end of the model to the other when the frequency was increased from 40 cps to 160 cps. When the skin of the arm is placed in close contact with the membrane, the vibrations are localized in a quite narrow section of the membrane, so that any change in frequency can be detected by a change in the locus of stimulation. The localization is as sharply defined for pure tone pulses of the length of two sine waves as for continuous tones. The localization of pure tones along the membrane is practically instantaneous.

The sharp localization in spite of the flat distribution of vibrations along the membrane is produced by the inhibitory effects of the skin. Their influence and magnitude are demonstrated by various experiments.

Some basic relations between nerve density on the cortex, threshold, and loudness increase on the skin are pointed out in the hope that they will later enable us to determine the differences between the organ of Corti and the simple skin membrane. This would be helpful to our understanding of the nature and function of the complicated structure of the organ of Corti. On the whole, in the observation of pitch of pure tones, the simple skin-model is as useful as the organ of Corti itself. The differences become apparent only in the observation of more complex sounds.

Two models were used to investigate the possibility of obtaining effects similar to the stereophonic effects in hearing.
Comparison of Hyponasality, Hypernasality, and Normal Voice Quality on the Intelligibility of Two-Digit Numbers
Authors: Moser Henry M. , Dreher John J. , Adler Sol
Published: September 2005

Six Eastern and General American speakers, using hyponasal, hypernasal, and normal voice qualities recorded random lists of two-digit numbers for presentation in noise to 11 trained listeners, all of whom had 32 hours practice in listening and testing in noise. Results indicate that, while voice qualities acted in a relatively similar manner at both signal-to-noise ratios tested, hypernasality was destructive to intelligibility under both conditions, hyponasality was destructive at the milder noise level, and normal delivery was best throughout.
Experimental Studies on Acoustic Radiation Pressure
Authors: Herrey Erna M. J.
Published: September 2005

An apparatus is described which allows one to measure the normal and shearing component of the force of radiation pressure exerted by an ultrasonic beam through water on an intercepting disk. Results of measurements on an absorbing and on a reflecting disk are seen to confirm the theory of Brillouin that radiation pressure is due to a state of unidirectional stress in the region of a plane progressive wave and that it is properly represented by an anisotropic stress tensor. It also appears that the apparatus with the absorbing disk provides a very simple, and at the same time, accurate device for the absolute measurement of the power output of an acoustic transducer. Furthermore, it is shown how the measurement of radiation force components with this apparatus can be used for the determination of the average reflection-, transmission-, and absorption-coefficients of any sample material as functions of angle of incidence. Results of measurements on cork, aluminium, and steel plates are presented.