bluuebunny/crossref_metadata_2025 huggingface dataset:
Volume Viscosity of the Molten Chlorides
Authors: Marchessault J. G. , Litovitz T. A.
Published: September 2005

Measurements of ultrasonic attenuation were made in a series of molten chlorides. The data indicate the existence of a structural volume viscosity whose activation energy differed from that for shear flow by from 1 to 6 kcal/mol. The ratio of volume to shear viscosity is the highest found so far (for an isothermal process) in any liquid, lying in the range 17 to 27. It appears that this ratio rises with the strength of intermolecular bonding in the liquid. The logarithm of this ratio of volume to shear viscosity was found to be linearly related to the entropy of fusion. Application of the Eyring-Hirai “hole” theory of structural relaxation yielded reasonably good agreement with the measured values.
Response and Radiation of Structural Modes Excited by Sound
Authors: Smith P. W.
Published: September 2005

The response to sound and consequent sound radiation (“radiation scattering”) for one linear resonant mode of a part of a larger structure are analyzed for a general structure. A modal reciprocity relation is established between modal radiation resistance and the transfer function which relates incident sound pressure to modal (“generalized”) force in the absence of motion. Response and resonant scattering are also analyzed for excitation by noise. When all angles of incidence are equally probable, the means-quare response velocity is inversely proportional to modal stiffness and proportional to the fraction of total damping attributable to radiation; it is independent of all other characteristics of the structure.
On the Perception of the Frequency Ratio 55:32
Authors: Ward W. Dixon
Published: September 2005

The fact that untrained listeners categorize the musical interval between two tones having a frequency ratio of 55:32 as being a major sixth is shown to be a most reasonable outcome on the basis of present knowledge.
Quality of Piano Tones
Authors: Fletcher Harvey , Blackham E. Donnell , Stratton Richard
Published: September 2005

A synthesizer was constructed to produce simultaneously 100 pure tones with means for controlling the intensity and frequency of each one of them. The piano tones were analyzed by conventional apparatus and methods and the analysis set into the synthesizer. The analysis was considered correct only when a jury of eight listeners could not tell which were real and which were synthetic tones. Various kinds of synthetic tones were presented to the jury for comparison with real tones. A number of these were judged to have better quality than the real tones. According to these tests synthesized piano like tones were produced when the attack time was less than 0.01 sec. The decay can be as long as 20 sec for the lower notes and be less than 1 sec for the very high ones. The best quality is produced when the partials decrease in level at the rate of 2 db per 100 cps increase in the frequency of the partial. The partials below middle C must be inharmonic in frequency to be piano like.
Generation and Detection of Ultra-High-Frequency Sound in Liquids
Authors: Dunn Floyd , Breyer John E.
Published: September 2005

Two schemes using piezoelectric plates to produce acoustic waves in liquid; in the kilomegacycle frequency region are described. The use of the thermoelectric method of detecting the acoustic energy in liquids is discussed briefly. Data obtained by these techniques are presented.
Two Verifications of the Karal-Keller Theory of Wave Propagation
Authors: Lang H. A.
Published: September 2005

The Karal-Keller theory is applied to an explosive source in a spherical cavity where it becomes exact because the displacement series terminates after two terms. This solves the source problem as a necessary preliminary to considering both free surface reflection in a homogeneous media and propagation in inhomogeneous media. The dual problem of the purely rotational source is also solved. Collectively, the two problems illustrate how the asymptotic theory may, by terminating, yield an exact solution for an arbitrary waveform.
Earphone Response and Onset Time
Authors: Tobias Jerry V. , Jeffress Lloyd A.
Published: September 2005

Measurements were made of the transient response of PDR 8 earphones. These data indicate that the original estimate of the onset duration of auditory stimuli can be revised downward to 0.8 msec. Implicit in the results is a caveat on the faith one should have in the output of commonly used earphones for short signals.
Some Applications of an Ultrasonic Light Modulator
Authors: Liben William
Published: September 2005

Some new applications of the ultrasonic light modulator are described. It has been used as an electrical signal frequency analyzer, noise analyzer, and for the production of a set of uniformly spaced optical markers. Included are design formula for the optical system and ultrasonic resolution.
Computer Program for Pitch Extraction
Authors: Gold Bernard
Published: September 2005

It is assumed that pitch extraction obtained by visual inspection of a speech wave is the best pitch extraction obtainable. A computer program has been written which aims to detect pitch as well as this ideal. The program features three separate tests and a method of combining them which gives a composite result which is better than any of the individual tests. For most of the sentences tried, the computer results were as good as the “ideal.” Informal listening indicates that a pitch detector which performed as well as the program would appreciably enhance Vocoder quality.
Some Aspects of Fundamental Frequency and Envelope Amplitude as Related to the Emotional Content of Speech
Authors: Lieberman Philip , Michaels Sheldon B.
Published: September 2005

Pitch pulses were electronically derived from the utterances of three male native speakers of American English who each read eight neutral test sentences in certain “emotional” modes, i.e., as a question, an objective statement, a fearful utterance, a happy utterance, etc. A fixed-vowel POVO-type synthesizer was excited by these pitch pulses. The pitch perturbations, or rapid variations in the fundamental excitation rate, could be smoothed out and the POVO could be amplitude-modulated with a signal derived from the original speech envelope amplitude.

Tapes were recorded and presented to separate groups of naive listeners who categorized the emotional modes in forced judgment tests. Results of the tests show that with unprocessed speech, the listeners were able to correctly identify the emotional content 85% of the time. When only pitch information was presented, correct identification was made 44% of the time. When amplitude information was added to the pitch information, the identification rose to 47%. Smoothing the pitch information with a 40-msec time constant reduced the identifications to 38%, while 100-msec smoothing reduced the identifications to 25%. A 120-cps monotone with amplitude information derived from the original speech envelope amplitude resulted in 14% identifications.
Loss Factors of Viscoelastic Systems in Terms of Energy Concepts
Authors: Ungar Eric E. , Kerwin Edward M.
Published: September 2005

The definition of loss factor in terms of energy quantities is reexamined, particularly as it applies to composite viscoelastic systems. A restatement of this definition in terms of a corresponding viscoelastic spring is used to show that this definition is extremely useful for massless (ideal viscoelastic spring) systems, but may be applied unambiguously to spring systems with a single attached mass only at resonance. Simple relations are derived which express the loss factors of series-parallel arrays of massless viscoelastic springs in terms of properties of the individual components; application of these relations to damping analyses of composite structures should result in considerable economy of effort.
Solution of the Wave Equation in a Medium with a Particular Velocity Variation
Authors: Potter D. S. , Murphy S. R.
Published: September 2005

The formal solution of the scalar wave equation is presented for a point source in a medium which is inhomogeneous one dimension with a particular sound-velocity dependence. This solution is another of the class of integrable solutions, based upon Bessel's equation, which can be expressed in closed form, allowing the use of available tables for numerical work. The particular sound velocity chosen, c = c0z(z2 − a2)−12, is interesting in that it corresponds in part to actual underwater measurements and that it yields a shadow zone.

In addition, an integral involving products of Bessel functions is reduced to a simple form, not found in the literature on Bessel functions.
Reciprocity Parameters Derived from Radiated Power
Authors: Trott W. James
Published: September 2005

The radiated sound power in the near and far fields of transducers are equated to obtain the plane-wave and cylindrical-wave reciprocity parameters from the spherical-wave reciprocity parameter.
Experimental Investigation of an End-Fire Array
Authors: Bellin J. L. S. , Beyer R. T.
Published: September 2005

Experiments are reported on the measurement of the scattered pressure from two finite-amplitude, collinear sound beams. The measurements were carried out at a carrier frequency of 13.5 Mc in water and of 350 kc in air. The slope of the half-pressure angle vs difference frequency curve agrees well with that predicted by Westervelt, although the radiation pattern measured experimentally was in each case more directive than predicted by the theory.
Moments of the Output of Linear Random Systems
Authors: Bogdanoff J. L. , Kozin F.
Published: September 2005

A method is presented for determining the differential equations of the output moments of a linear random system in which the coefficients are components of vector Markov processes. The method is based upon well-known results in applied stochastics. It appears considerably simpler than methods recently suggested for studying the behavior of linear random systems.

A stability criterion previously published is obtained with little effort. Reasons are presented for disagreeing with published results that mean motion of linear random systems with Gaussian parameter variations is not influenced by these variations.
Masking and Interaural Phase. II. 167 Cycles
Authors: Jeffress Lloyd A. , Blodgett Hugh C. , Deatherage Bruce H.
Published: September 2005

Masking level differences obtained for 167 cps are presented. Some involved shifting the phase of the signal through various angles, and others, shifting the noise in interaural time. Where the experimental conditions are comparable to Hirsh's at 200 cps, the data agree very closely with his. The data obtained with various interaural time differences in the noise are shown to differ sharply from comparable data taken at 500 cps.
Measurements of the Near Field of an Approximately Plane Radiator
Authors: Carrell R. M. , Backus R. A.
Published: September 2005

A rectangular array, two feet square, of 67 small loudspeakers is used to generate an approximately plane wave field. The results of measurements of pressure and phase distribution made near the surface of the composite radiator are presented. The application of such an array to the testing of noise canceling microphones is discussed.
Some Factors of Vowel Duration and Their Cross-Linguistic Validity
Authors: Delattre Pierre
Published: September 2005

As a complement to the discussion started by Arthur House, new facts and new arguments are furnished which reinforce the theory according to which: (a) many variations in vowel duration are physiologically conditioned, (b) and those variations that are conditioned, and not phonemically learned, are due to factors that are cross-linguistically valid.
Acoustical Interferometer Employed as an Instrument for Measuring Low Absolute Temperatures
Authors: Cataland G. , Plumb H. H.
Published: September 2005

Values of absolute temperatures at 2° and 20°K have been determined from experimental measurements of the speed of sound as a function of pressure in helium gas. The acoustical interferometer was the instrument employed in the measurements, and the accuracy achieved in the experiment indicates that sonic thermometry at low temperatures may be competitive with other conventional thermometry techniques.
Effects of Wire Resonance on Aeolian Tones
Authors: Powell Alan , Shulman A.
Published: September 2005

It has been found that the oscillatory flow which generates aeolian tones when a wire is exposed to a steady wind may adjust itself to the resonant frequency of the wire, if it is flexible, over a speed range up to 10% or so in the experiments reported. The tone is then very steady and relatively strong. On each side of this range are regions where the frequency is unsteady, lying between the resonant one and the fixed-wire aeolian tone.
Some Results of the Analysis of Singing Voice
Authors: Rshevkin S. N.
Published: September 2005

Oscillographic records of some masculine voices were made by means of high quality electroacoustic devices. Vowels u(oo), o, a (ah), e, i (ee) of various pitch from 94 cps to 490 cps were recorded. The records lasting 0.1 sec were made at the moment of the stationary, prolonged sounding of the vowel. The harmonic analysis of different periods of the voice of an artistic singer showed a sharply defined increase of harmonic components in two narrow bands of the spectrum: about 400–600 cps and about 2200–2800 cps. Doubtless in well-trained, good voices there are characteristic “singing formants,” practically the same for all vowels. For the vowels “u” (oo) and “i” (ee), the lower formant sometimes gets as low as 250–300 cps. The higher formant is characteristic for a “metallic” timbre of voice. In the voice of an inexperienced singer (baritone) with a strong but sharp timbre of voice and noticeable fall of loudness higher than mi♭ (325 cps), these sharply defined singing formants are not observed; the whole region of harmonies higher than 1500 cps shows a general increase. It is suggested that the singer arranges formant regions characteristic of a vowel and necessary for good articulation only in the beginning of a vowel (in the period of attach) after which he quickly rearranges the vocal apparatus to the singing position, which is almost the same for all the vowels. The quick and distinct rearrangement to the singing position is a necessary quality of a trained voice. The above-mentioned results agree with our former investigations of 1927 and with the investigations of Bartholomew who found a high singing formant in the region about 2800–3200 cps.
Some Under-Ice Acoustic Ambient Noise Measurements
Authors: Macpherson J. D.
Published: September 2005

Ambient-sea-noise measurements have been made under complete and partial ice cover in the Gulf of St. Lawrence. Noise levels as much as 25 dB below Knudsen's sea state zero bare Been measured under solid ice.
Audibility of Nonlinear Distortion in Sound Transmission Systems
Authors: Rimsky-Korsakov A. V.
Published: September 2005

The nonlinearity to be allowed in sound transmission systems is usually found experimentally. For this purpose a group of persons is proposed to find (by listening to a program) the grade of nonlinearity at which distortion is noticeable. The resulting data may depend on the hearing sharpness of these people, on the sequence of the experiments, on the form of nonlinearity, frequency band, and transmitted program. Therefore the value of such data is limited. Distortion hearing thresholds for various programs and forms of nonlinearity were measured. In a single experiment for a group of people they are distributed in a good agreement with the Gaussian law. A method of computing the nonlinear distortion audibility was developed. The transmitted signal is considered to be a stationary oscillating process with normal distribution law. The probability for the nonlinear products to exceed the hearing threshold which is influenced by the main transmitted signal (masked) was computed. Calculation for a constant amplitude spectrum signal and transmission system with a frequency band 100–5000 cps. and various distortion factors was done. The probability of noticing second-order nonlinear products for a distortion factor = 3% was found to be 0.035; as for a distortion factor = 5% nearly 1/7 to 1/5 of the whole program may be spoiled by nonlinear effects.
Diagnosis and Cure of Erratic Velocity Distributions in Sonar Projector Arrays
Authors: Carson David L.
Published: September 2005

Often, well-designed arrays of electroacoustic transducer elements radiating into water exhibit erratic behavior in the transmission-frequency band such that the distribution of magnitude and phase of element velocities across the array appears to be independent of the distribution of electrical driving voltages or currents. Even at low drive levels, directivity patterns and source levels deteriorate, and some elements may even experience structural failure because of excessive motion of the radiating face. The cause of this unsatisfactory behavior is diagnosed and relatively simple curative measures are presented. In particular, the cure requires a separate tuning reactor for each element. The reactors are identical, but must be selected by a new criterion. If modular drive is used, the drivers must have a very low or a very high internal impedance, depending on circumstances.
Comparison of Experimental and Theoretical Image Interference in Deep-Water Acoustics
Authors: Pedersen Melvin A.
Published: September 2005

Experimental and theoretical interference patterns, resulting from the interaction between signals arriving by a direct and by a surface-reflected path, are compared for three receiver depths at frequencies of 530 and 1030 cps. Propagation losses are computed on the basis of ray theory for a velocity-depth profile consisting of three linear segments. Agreement between ray theory and experiment is excellent at ranges less than that of the first shadow zone or the first caustic. Theoretical losses based on the assumption of isovelocity water also agree well with experiment at the shorter ranges, but can depart markedly at longer ranges in the interference pattern because of the effect of refraction on both travel time differences and component amplitudes.
An Apparatus for Alteration of the Playback Time of a Sound Record
Authors: Springer Anton M.
Published: September 2005

As a rule, the frequency is changed by altering the reproduction speed of the magnetic tape of a sound record. There are two quite different ways to alter the playback time without thus changing the frequency of the recorded material. While by electronic means a time expansion in the proportion of 1:2 or even 1:4 is possible, by mechanical means only a continual change of the reproduction speed can be made with a time expansion or a time compression without any loss of the sound record's quality or character of sound. With our system, there is also no need to rerecord onto another magnetic tape. The apparatus works so perfectly that on a scale which has been gauged in percent of the recorder speed, the reproduction time can be altered from 50 to 200% without changing the frequency compared with the record. A sound record with music or speech can be reproduced as well with a time expansion of 200% as with a time compression of 50% by which the rhythms or the time are altered. Two essential elements have led to this result: the special playback head and the electromechanical differential. The acoustical time regulator has been constructed as an additional apparatus for ordinary magnetic tape recorders. It can be connected, with a few manipulations, thus leaving out the standard playback head.
Existence Region of the Tonal Residue. I
Authors: Ritsma R. J.
Published: September 2005

The residue phenomenon makes it necessary to assume that many areas of the basilar membrane may give rise to sensations of widely different pitch, depending upon the pattern of stimulation. In the case of steady-state signals, the place of maximal stimulation will be a measure of timbre whereas the pitch will depend on the quasi-periodicity of the signal. A closer study of the residue phenomena is of interest, since the residue implies situations where average frequency and periodicity are separate parameters and, to a certain extent, may be varied independently. The literature shows that attempts to establish the residue have not always been successful, mostly due to the specific frequency combinations chosen. In this paper, measurements are described on an harmonic complex consisting of three components, with variable modulation depth and frequency. This harmonic complex is found to have a decidedly tonal character within a limited frequency region. The boundaries for a complex with a modulation depth of 100% are roughly given by values of the center frequency f<5000 cps, and values of the spacing frequency g⩾0.05f. A theoretical model of a pitch-extractor is presented which accounts for the observed frequency region of the tonal residue.
Displacement Pickup for Measuring the Motion of a Loudspeaker Cone at Many Points
Authors: McLachlan K. R.
Published: September 2005

In the experimental investigation of the response of a loudspeaker a knowledge of the motion of the cone at many points is required. Such measurements present special difficulties, which arise from the shape of the loudspeaker and from the fact that the mechanical and acoustical loading of the cone, due to the measuring device, must be negligible. A method of measurement has been developed in which a beam of light is modulated by the motion of the cone and the result displayed on a cathode-ray tube. The sensing unit is automatically scanned over a radius of the cone and some 30 points on any radius may be sampled. The results are recorded and either the steady state or transient response at the selected points can be obtained. The equipment is calibrated statically and tests have shown that this calibration is valid up to at least 20 kc/sec. Vibration amplitudes from ±0.001 in. to ±0.125 in. can be measured with a linearity of better than 5%. In addition to the measurement of the response of loudspeakers, the equipment is useful in many vibration problems where the mechanical impedance of the vibrating system precludes the use of conventional vibration pickups.
Effect of Temporal Spacing on Temporary Threshold Shift from Impulses
Authors: Ward W. Dixon
Published: September 2005

Thirteen normal-hearing observers were exposed to 60 high-intensity pulses presented at 4 different interpulse intervals: 1, 3, 9, and 30 sec. Temporary threshold shifts (TTS) were measured at frequencies from 500 to 13 000 cps. Results indicate that the TTS produced by 1-, 3-, and 9-sec interpulse intervals are essentially equivalent. Considerably less TTS was produced by the 30-sec interval during the first minute or two of recovery, but by 5 min after cessation of the pulses, this difference had nearly disappeared. This supports the hypothesis of Hirsh and Bilger that two separate fatigue or recovery processes are involved in TTS. It is concluded that total number of impulses is more important than exposure time per se in predicting TTS (and so, presumably, permanent loss) from impulse noise.
Theory of Ultrasonic Delay Lines for Direct-Current Pulse Transmission
Authors: Onoe Morio
Published: September 2005

A unified analysis of ultrasonic delay lines is presented with particular attention paid to the characteristics of direct-current pulse transmission. The analysis can be applied to any delay line, whether piezoelectric or magnetostrictive, regardless of whether the mode of transmission is longitudinal, shear, or torsional, as long as the motion is adequately described by the one-dimensional theory on which the equivalent circuits are based.

Characteristics in the time domain are obtained in terms of the time-shift operators of Laplace transform calculus. This makes it possible to easily obtain the output waveform for any arbitrary input. Three transducer configurations are discussed; namely, a line with transducers in the middle of the delay medium (Case A), a line with one of the transducers at the free end of the delay medium (Case B) and a line with transducers at both free ends of the delay medium (Case C).

The latter two configurations are especially useful for a delay line made of a ferrite or piezoelectric ceramic, both of which are available in limited length only due to manufacturing difficulties. Cascading of several pieces of material in order to obtain a longer delay than that which is available using a single piece is discussed. The effects of acoustic mismatching at bonding points on the signal-to-noise ratio and on the ringing in the output are presented.
Propagation of Elastic Waves in Plates and Bars of Solid Material with Low Shear Modulus
Authors: Tamm Konrad
Published: September 2005

Sound propagation in solid media of finite cross section is very complicated in the general case, due to the fact that the boundary conditions can be fulfilled only by superposition of both longitudinal and transverse waves. It can be shown that this picture will be much clearer for rubber-like materials (with low shear modulus, the Poisson constant being nearly 0.5), because the velocity of the transverse waves is much smaller than that of the longitudinal waves. As long as all dimensions normal to the axis are small compared with half the wavelength of the longitudinal wave, the dispersion of the phase velocity is given by the shear modulus as in an incompressible medium with finite shear modulus. Above this frequency limit the influence of the bulk modulus overcomes that of the shear modulus; and if energy losses exist, it will alone determine the behavior. The phase velocity then will nearly be equal to that of the different modes of the longitudinal wave in a liquid column. Measurements of phase velocity and attenuation confirm that below this limiting frequency the damping is determined by the loss factor of the shear modulus, while above the limit a much lower damping exists, a result of the smaller influence of the shear modulus.
Measurement of the 25°C Zero-Field Elastic Moduli of Quartz by High-Frequency Plane-Wave Propagation
Authors: McSkimin H. J.
Published: September 2005

An analysis made of plane wave propagation in different directions of quartz with possible piezoelectric effects considered. A method of determining the zero-field elastic moduli is described which should be suitable for measurements versus temperature and hydrostatic pressure. Values for elastic moduli obtained at 25°C are compared with the literature.
Low- and High-Mode Dispersion in Elastic Plates
Authors: Tolstoy Ivan , Usdin Eugene
Published: September 2005

This is an analysis of dispersive properties of elastic plates in vacuo. For low modes there exists conclusive experimental verification of these properties. Model studies show prominent arrivals having the proper spectra and velocities for group velocity maxima and minima corresponding to several symmetric and antisymmetric modes. In addition, detailed calculations based upon exact formulas predict some new and, as yet, unconfirmed properties of plates; e.g., negative phase velocities. These appear in the theory as negative group velocities, but the space form of the wave equation being symmetrical with respect to direction of propagation, this implies phase fronts moving towards the source. New results concerning high modes of propagation are also displayed. These modes are of considerable theoretical interest since they belong to the transition region between the domains of validity of the wave and ray theories. The structure of the symmetric and antisymmetric fiftieth mode dispersion curves illustrates that for a given angle of incidence the propagating energy will be either chiefly shear or chiefly compressional, passage from one to the other corresponding to energy transfer between symmetrical and antisymmetrical modes of propagation. A comparison with multilayered liquid wave guides is given.
Successful Method of Attack on Plane Progressive Finite Waves
Authors: Fay Richard D.
Published: September 2005

The characteristic feature of the method is that at any point in the sound field the conservation criteria are expressed in terms of the speed of propagation and the instantaneous values of the particle velocity, the excess pressure, and the excess density. These criteria, together with the adiabatic assumption, determine explicit relations between any two of these quantities. Excess pressure and excess density are here defined as departures from the equilibrium values that exist at the instant when the particle velocity is zero. For waves of finite amplitude, these equilibrium values, as well as the speed of propagation, are found to depend on the intensity. The increment in the speed of propagation does not agree with that obtained by classical methods of analysis. The discrepancy is found to be due to the omission in the classical forms of the continuity criterion of a term that specifies the effect of the rate of change in the speed of propagation. [Supported in part by Office of Naval Research Contract N 5ori-07861.]
Attenuation of High-Amplitude Sound Waves in Exponential Horns
Authors: Rudnick Isadore
Published: September 2005

A large amplitude progressive sound wave will undergo distortion as it travels and eventually develop into a saw-tooth wave with shock fronts a wavelength apart. Such a wave will lose energy at a rate which is an increasing function of the amplitude. Exponential horns are often used as matching sections to sound sources. The problem of the distortion and consequent shock-wave propagation in such an infinite exponential horn has been investigated, and in particular the energy loss has been calculated. As is to be expected, the rate of energy loss is a monotonically increasing function of (1) the Mach number of the wave at the throat, and (2) the ratio of the frequency of the wave to the cut-off frequency of the horn. This can cause a serious limitation in the high-frequency power available in a wide-band system.
Flux of Angular Momentum and the Rayleigh Disk Problem
Authors: Westervelt Peter J.
Published: September 2005

A substantial simplification in the calculation of forces due to radiation pressure results from the application of the concepts of wave momentum [P. J. Westervelt, J. Acoust. Soc. Am. 23, 312 (1951); J. S. Pyett, ibid. 28, 156 (1956)]. It will be shown that a similar simplification occurs in calculating the torque on an object in a sound field in terms of the flux of angular momentum crossing a closed surface far removed from the scattering object. [This work has been supported by the U. S. Air Force, Wright Air Development Center.]
Measurement of Radiation Forces in a Cylindrical Sound Field
Authors: Embleton T. F. W. , Pyett J. S.
Published: September 2005

A long line source has been simulated by placing a horn terminating in a slot 8×14in.. between two large, rigid plane surfaces 8 inches apart. The resulting cylindrical sound field has been used for measurements of acoustic radiation forces. The force exerted on rigid spherical obstacles of up to 3 cm radius has been measured at distances within 10 cm of the source of the field. Forces of attraction have been found; their magnitude as a function of frequency, size of spherical obstacle and distance from the source is in agreement with theory [T. F. W. Embleton, J. Acoust. Soc. Am. 28, 155(A) (1956) and Can. J. Phys. 34, 276 (1956)]. This apparatus overcomes the difficulty of eliminating spherical waves from the sound field encountered in previous experiments with a short line source.
Acoustic Streaming Resulting from Localized Vibratory Excitation of a Membrane
Authors: Jackson Francis J. , Nyborg Wesley L.
Published: September 2005

It was reported previously [Elder, Kolb, and Nyborg, J. Acoust. Soc. Am. 26, 933(A) (1954)] that if a membrane bounding a liquid is caused to vibrate in a localized region the fluid adjacent to it will be set into steady vortex motion. One simple way to realize this situation is to bring a vibrating metal tip of circular cross section into contact from below with a membrane which supports a small body of liquid. A characteristic (axially symmetric) vortex motion then takes place near the tip in the liquid above, as may be seen by observation with a microscope and by use of indicating particles. Particularly high accelerations and velocities exist in a ring near the tip periphery. Streaming phenomena of this kind have now been observed under a variety of situations, at frequencies varying from 100 to 40 000 cps. Because of the associated convection and viscous stress such streaming is an important secondary cause of sonic irradiation effects. Sketches and photographs of streaming patterns will be shown, and theory for the motion discussed. [Supported in part by grant RG-4431 from the National Institutes of Health.]
Structure and Functions of the Sensory Hairs of the Inner Ear
Authors: Engström Hans , Ades Harlow W. , Hawkins Joseph E.
Published: September 2005

The structure and relationships of the hairs of the cochlear and vestibular sensory cells have been investigated in fixed and fresh tissue by light, phase contrast, and electron microscopy. The cochlear hairs closely resemble the stereocilia of the vestibular cells, but there are differences in size, number, and arrangement between those of the inner and outer hair cells. In the cuticlefree region of the cell surface, a basal body is found, corresponding to the single kinocilium on each vestibular cell. The stiff cochlear stereocilia are regarded simply as levers, transmitting mechanical energy from the overlying tectorial membrane by way of the cuticular plate to the basal body. It seems unlikely that their bending as such has the importance generally ascribed to it. In view of the great functional significance of modified kinocilia in other sense organs, the basal body, like the vestibular kinocilium with its associated mitochondria, membranes, granules, appears to be the essential excitable structure of the hair cells.
Advances in the Neurophysiology and Neuroanatomy of the Cochlea
Authors: Davis Hallowell
Published: September 2005

This review deals with a few selected areas in which significant advances have recently been made or are being made. The topics relate to the origin and significance of the dc polarization of scala media of the cochlea, to the variety and distribution of nerve endings, to the possible peripheral effects of the efferent nerve fibers, and to the pattern of activity of individual fibers of the auditory nerve.
Effect of Vibration on Convective Heat Transfer
Authors: Lemlich Robert
Published: September 2005

In order to study the effects of vibration on convective heat transfer, investigations were carried out in several systems. The major study [Ind. Eng. Chem. 47, 1175 (1955)] involved natural convection from horizontal electrically heated wires of three different diameters subjected to transverse vibration in air at frequencies ranging from 39 to 122 cps. Considerable improvement in the coefficient of heat transfer was obtained, even to the extent of quadrupling the film coefficient. The coefficient was observed to increase with both amplitude and frequency. The direction of vibration was without significant effect. To account for this latter observation, the concept of a “stretched film” surrounding the entire path of vibration is suggested. In addition, a pair of dimensionless correlations involving a vibrational Reynolds number are presented for vibration in air or other diatomic gases. An approximate extension to other fluid is also proposed. Additional studies into the effects obtainable with other types of vibration were also conducted. Vibration and pulsation were induced in turn in two double-pipe steam-to-air heat exchangers. Either by the use of musical reeds in the air stream or by periodically interrupting the air stream with a shutter, significant improvements in coefficient were obtained.
Lateralization of Acoustic Transients
Authors: Teas Donald C.
Published: September 2005

A series of experiments is reported in which the lateral position of the intracranial image resulting from acoustic transients presented via earphones is shown to vary with frequency content and sensation level (SL) as well as with interaural time differences. The experimental procedures followed, together with new physiological data from the inner ear and certain theoretical assumptions, permit an estimate of the effective neurophysiological waveforms for one of the acoustic signals. The data suggest that an anatomical substrate for a “timing signal,” if present at all in the auditory system, does not have its origin in the inner ear. The theoretical treatment suggests that the synchrony of the neural input may be a significant factor in localization.
Investigation of Acoustic Properties of Organic Substances in the Critical Region
Authors: Nozdrev V. F.
Published: September 2005

Results are given of an experimental and theoretical investigation of the velocity and absorption of ultrasonic waves in the critical region of the liquid-vapor system in 15 organic liquids. From extensive data obtained by optical and impulse methods a number of empirical rules may be established. A simple correlation is possible of sound velocity to other thermodynamic parameters of the liquid and saturated vapor phase in the critical region. From measurements of both ultrasonic absorption and velocity in the critical region for xylol, toluene, and ethyl acetate, their volumetric viscosity and specific heat may be calculated. Data on ultrasonic velocity and absorption in the supercritical region are also reported. The relevance of the results of this study for heat engineering is discussed.
Precision Measurements of Axial and Radial Resonances of Gas-Filled Cylindrical Resonators
Authors: Fritsche L. , Kneser H. O.
Published: September 2005

Resonator curves of axial and radial resonators (1–5 kc) have been analyzed at gas pressures between 5 and 750 mm of mercury. The effects of wall friction, as well as of classical and molecular gas absorption, are each discussed separately.
Middle-Ear Mechanics and Surgery for Deafness
Authors: Lawrence Merle
Published: September 2005

Békésy's contributions to our understanding of the mechanics of the middle ear are reviewed as they apply to present-day middle-ear surgery. In addition to discussing the transformer action of the middle ear, the paper describes several characteristics of stapes action and of the tympanic membrane with its associated ossicles. These latter points have generally been ignored by middle-ear surgeons. It is shown that the plungerlike action of the stapes and the mass of the head of the malleus and incus are extremely important in the proper operation of the normal ear.
Radial Modes of Oscillation in an Axially Symmetric Combustion Chamber
Authors: Clough Gail M. , Putnam Abbott A.
Published: September 2005

A fundamental study of flame-driven transverse oscillations in an experimental burner is being made. These oscillations are similar to those occurring in the combustion chambers of rockets, ramjets, and afterburners. The first radial mode and six combined first radial and axial modes were obtained in an experimental combustion system. Data are given on the effect of velocity, composition, mixing-chamber length, and location of the burner head with respect to the combustion chamber. Sound-pressure-level surveys for a few modes also are presented. [The work described in this paper was conducted under the sponsorship of the Aeronautical Research Laboratory of the Wright Air Development Center, Contract No. AF 33(038)-12656.]
Analysis of the Middle-Ear Function. Part I: Input Impedance
Authors: Zwislocki J.
Published: September 2005

A quantitative theory of the middle-ear acoustics is developed and expressed in terms of an electric analog. The analog network is based on the functional anatomy of the middle ear. The numerical values of its elements are derived from impedance measurements on normal and pathological ears and from anatomical data. It is shown that the input impedance of the analog agrees within the experimental error with the acoustic impedance at the eardrum, and that changes in analog parameters corresponding to known anatomical changes produce the same effect on its impedance characteristics as measured at the eardrum.
On Wave Impedance and Specific Impedance of Materials in Acoustics
Authors: Vogel Théodore , Laville Gaston
Published: September 2005

If impedance is defined as an operator that permits one to go from an “effect” back to a “cause” (in hydrodynamics, from velocity to pressure), it is seen that the impedance field of a wave is constant in the case of a plane wave, but only in this case. This absolute character of the impedance of a plane wave makes it possible to construct a standard of which a cylindrical example is described and discussed. The situation changes completely once a second dimension is introduced (a plane wave striking an oblique obstacle or a more complicated case); the specific character of the impedance of an obstacle is generally assumed but must be determined by experiment. A discussion of the possible conditions shows that one can choose between two assumptions, one of a specific normal impedance which compares the obstacle to a perfect fluid, and the other, of an oblique impedance which generalizes the preceding and makes it possible to consider the equivalent fluid as viscous or even to treat the obstacle as an isotropic solid. It is shown how one can verify experimentally which of the two hypotheses is applicable, and results of such a verification are presented.
Acoustical Techniques for Producing Cavitation
Authors: Rosenberg Murray D.
Published: September 2005

Acoustic waves of high-pressure amplitudes will produce cavitation in many liquids and semisolids. The forms of cavitation produced, vaporous or gaseous, are described. Specific applications help determine both the form of cavitation desired and the mechanism to be used for its generation. Consideration is briefly given to applications such as industrial processing, the growth and collapse of gaseous-type and vaporous-type bubbles, cavitation damage, noise, luminescence, etc. Comparisons are presented between the qualitites of progressive-wave and standing-wave systems, low and high Q systems, focused and plane waves, and volume and interface effects. The types of focusing systems are outlined. The design of lenses and paraboloidal focusing units, and the use of shading techniques for the control of diffraction patterns are carefully discussed. Some problems involved in the construction of these systems are presented.
Onset of Ultrasonic Cavitation in Tap Water
Authors: Strasberg Murray
Published: September 2005

The conditions influencing the onset of acoustically-induced cavitation in tap water have been investigated, with special attention to the role of air-filled nuclei. Cavitation was induced by exciting the water, contained in a spherical flask, at the resonant frequency of a radial mode near 25 kc/sec. Air-filled nuclei were detected by observing the reverberation decay of sound in the sphere at frequencies from 150 to 700 kc/sec, the presence of undissolved air cavities causing an increase in the decay rate. The results indicate that tap water standing undisturbed for several hours contains no air nuclei with radii larger than 5 × 10−4 cm, even when the water is supersaturated with dissolved air. The smaller nuclei (not detectable by reverberation decay) seem to become progressively smaller, for the measured threshold sound pressure at the onset of cavitation increases several-fold as the water stands undisturbed for several days. The observed influence of the air content on the threshold peak sound pressure Pt is given by Pt≃A1 − A2Pe where Ps, is the equilibrium pressure of the dissolved air, and the constants have the values A1=612 atmos, A2=4, at 22°C and one atmosphere static pressure. The variation of the threshold pressure with varying static pressure P0 depends on the direction of the pressure change; in the increasing direction, dPt/dP0 is larger than it is in the decreasing direction.
Performance and Applications of Hydrodynamic Oscillators
Authors: Bouyoucos John V.
Published: September 2005

A class of hydrodynamic oscillators is being developed which shows considerable promise for sonic and ultrasonic applications involving large acoustic power requirements. These devices convert liquid flow energy into acoustic energy with conversion efficiencies that can exceed 50% in favorable circumstances. The performance characteristics of a low-frequency (1000 cps) and a high-frequency (20 kcps) oscillator will be described. Problems associated with the delivery of the generated acoustic energy to the site of its application will be discussed. [This work was supported by the Office of Naval Research.]
Mechanism of Destruction of Solid Surface Films by Acoustically Induced Cavitation
Authors: Rosenberg L. D. , Bebtchouk A. S. , Makarov L. O.
Published: September 2005

The cavitational destruction of a thin layer of varnish put on a glass plate was studied by means of high speed photography at the rate of 2000 frames per second. Experiments were carried on in an inactive liquid (water) at the frequency 8000 cps. It was found that the destruction of the film is caused at least by two different factors. Primarily, it is observed as the result of big cavitation bubble collapes in the immediate vicinity of the surface. The obseravation of such bubbles indicates large amplitudes and complex forms of vibration. It is important to note that the process itself of bubble formation and its oscillations at the very surface of the film are without influence on the film; but the bubble collapse leads in the first 1/2000 sec to destruction of the film extending on a circle with the center coinciding with the position of the bubble at the moment of collapse. Another type of destruction is caused by small bubbles with smooth surfaces which quickly penetrate between the film and the glass at a destroyed spot, causing small irregular bits of film to detach from the surface.
Pneumatic Generators of Intense Ultrasound
Authors: Gavreau Vladimir
Published: September 2005

Toroidal whistles derived from the police whistle are described. Their operation at low pressure—oscillation of the air jet produced by the emitted sound, conditions to obtain high efficiency (30%), and pure sinusoidal tone without harmonics is discussed. Their operation at high pressure—oscillations produced by the air jet returning to strike at its base, edge sonnd superposed to the other components of the emitted complex sound, high-frequency ultrasonic components, but lower efficiency—is described. The equation of whistles and calculation of their theoretical efficiency are given. Formulas of the toroidal whistles are presented. The role of the horn: transformation of an interrupted air jet into sonic and ultrasonic waves. Auxiliary resonant cavity allowing the adaptation of horns to whistles. Contradictions between the theory of horns and the experimental results: no cut-off frequency; wide open horns are not suitable for ultrasounds. Practical calculation of annular exponential horns for emission of plane waves. Batteries of whistles (“whistle-panels”). Necessity of synchronization. Direct coupling; coupling by resonant tubes. Synchronization by means of an auxiliary nozzle (“the acoustical triode”). Levavasseur's whistle with auxiliary nozzle for ultrasonic whistle-panels. Synchronization by means of whistles, of sirens, of loudspeakers. Advantages and disadvantages of whistles and of ultrasonic sirens. Applications are described.
Jet Engine Noise Reduction Research at NACA
Authors: Sanders Newell D. , Callaghan Edmund E.
Published: September 2005

Results of experiments with various noise reduction devices are described. Experiments were conducted with a full-scale turbojet engine on an outdoor thrust stand which permitted essentially free-field measurements. The results confirm the findings of other investigators showing that some reduction in noise can be achieved although outstanding improvements have not been achieved. The work is still in progress.