bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurements of Hearing Acuity Among Submariners and Noise Levels in Working Compartments
Authors: Webster J. C. , Solomon L. N.
Published: September 2005

To study the prevalence of heating losses among submariners, and their possible causes and consequences, the NEL warble tone hearing test was administered to 1053 submariners. Heating losses of less than 7 db at 500 cps and 5 db at 1000 cps could not be measured due to ambient noises in the testing areas. At the other test frequencies (2000, 4000, and 7000), any positive value of hearing loss could be measured.

It was found that approximately 10 percent of all men tested had high frequency heating losses of 18 db or greater (at 4000 and 7000 cps). A comparison of the hearing losses of enginemen to those of all others as a function of time on boat, for each frequency, showed that in general the enginemen had greater losses at all frequencies although there were minor reversals. The amount of loss was slightly less than expected from previous findings on industrial workers.
Sound Level Discrimination and Variation of Reference Testing Conditions
Authors: Pollack Irwin
Published: September 2005

The accuracy of discrimination of small changes in sound level was examined as a function of the magnitude, temporal, and dimensional aspects of the variation between two reference testing conditions. Precision of sound level discrimination declined as: the magnitude of the sound level difference between the two reference conditions increased and as the frequency of occurrence of shifting between the two reference conditions increased. Of lesser importance was the temporal interval between successive discriminations, variation in the audio-frequency of the reference signals, and the predictability of the to-be-presented testing conditions. The results are considered in terms of a preliminary analysis of psychological dimensions in auditory discrimination.
Sonoluminescence: A Discussion
Authors: Jarman Peter
Published: September 2005

A brief summary of existing knowledge about sonoluminescence is given. Various theories of the origin of this luminescence are discussed. The author concludes that sonoluminescence is basically thermal in origin and that it might possibly arise from microshocks with the collapsing cavities.
Auditory Thresholds of the Cat
Authors: Neff William D. , Hind Joseph E.
Published: September 2005

The auditory thresholds of the cat have been obtained by the conditioned response method. Tests were made for frequencies from 62.5 to 60 000 cps. The upper limit of the cat's hearing is in the neighborhood of 60 000 cps. A comparison of threshold curves for cat and man suggests that the cat may be slightly less sensitive than man for frequencies of 500 cps and below. Sensitivity for the range 500 to 4000 cps is almost the same. For higher frequencies the hearing of the cat is distinctly superior to that of man.
Vibration Patterns of Loaded Barium Titanate and Quartz Disks
Authors: Shaw E. A. G. , Sujir R. J.
Published: September 2005

In previous work, the normal surface displacement patterns of thick barium titanate disks vibrating in various normal modes have been obtained using multiple-beam optical interference. This technique has now been used to determine the effect of loading a disk with a liquid in contact with one plane surface. It is found that the discrete modes observed with an unloaded disk begin to merge so that the vibration patterns show a continuous transition with changing frequency as one passes from one mode to the next in the “thickness resonance” region. The radiation damping of the individual modes is appreciably less than the theoretical value, but the bandwidth covered by the group is appreciably greater than is to be expected from the simple theory of thickness resonance. In the case of a quartz disk, two modes with a frequency separation of 0.5% merge fairly completely when the disk is loaded, and the vibration patterns indicate composite motion of a more uniform character than that of either mode alone.
Isomorphisms between Oriented Linear Graphs and Lumped Physical Systems
Authors: Trent Horace M.
Published: September 2005

A unifying principle is presented whereby all finite lumped systems can be analyzed by a single technique, no matter how complex the system may be. This central principle is the existence of a linear graph which is isomorphic to the dynamical properties of the elementary parts of the system and which shows how the parts are connected together.

An analysis of a lumped system begins with a conceptual decomposition of the system into a number of simple parts, each of which has known dynamical properties. It is shown that if two types of scalar variables can be found such that (1) they define, with the aid of system parameters, the dynamical properties of each part of the system, (2) the first type obeys the MESH LAW, (3) the second obeys the INCIDENCE LAW, and (4) physical dimensions of appropriate products of the two types are consistent, then there exists a linear graph isomorphic with the dynamical properties of the system as described by the variables so selected. Trivial additions to the isomorphic graph yield a schematic diagram for the system. It is then shown that the algebraic properties of the schematic diagram can be used to generate in a straightforward manner a set of equations, on either the nodal or mesh basis, describing the dynamics of the system as a whole. The isomorphic graph is also the key ingredient in establishing complete analogy. Formal procedures for establishing complete analogies are presented.
Dynamics of a Hollow, Elastic Cylinder Contained by an Infinitely Long Rigid Circular-Cylindrical Tank
Authors: Baltrukonis J. H. , Gottenberg W. G. , Schreiner R. N.
Published: September 2005

Dispersion equations are derived for the propagation of transverse waves within an infinitely long thick-walled hollow elastic cylinder which is perfectly bonded along its outer cylindrical surface to an infinitely long rigid circular cylindrical tank. In the case of infinite wavelength the dispersion equations reduce to two uncoupled frequency equations; one defining the natural frequencies of free vibrations of the hollow elastic core in the antisymmetric axial shear mode and the other defining the natural frequencies of plane strain vibrations. Some numerical results are presented for the dispersion equations and the two frequency equations and references are given to more detailed results.
Fluctuations in Surface-Reflected Pulsed cw Arrivals
Authors: Brown M. V. , Ricard James
Published: September 2005

A pulse of 168-cps sound was scattered from the ocean surface and analyzed for fluctuation as a function of the angle of incidence. A (cosφ)2.5 relation is found between the relative standard deviation of the energy and the incident angle, as measured from the normal.
Phase Velocity and Absorption Measurements in Water Containing Air Bubbles
Authors: Fox Francis E. , Curley Stanley R. , Larson Glenn S.
Published: September 2005

The phase velocity and absorption of a continuous train of sound waves in water containing air bubbles were measured as functions of frequency from 10 kc/sec to 1 mc/sec. The data are in fairly good agreement with theories by Meyer and Skudrzyk and Carstensen and Foldy. For the bubbles investigated which constituted 0.02 percent of the volume, phase velocity varied from 500 m/sec to 2500 m/sec and peak absorption was over 30 db/cm.
Determination of Sound Absorption Coefficients Using a Pulse Technique
Authors: Rogers Charles L. , Watson Robert B.
Published: September 2005

A pulse method of determination of sound absorption coefficients using a sound mirror to produce directed sound pulses allows determination of the coefficients by essentially a free field method but within the confines of an ordinary laboratory. Average pulse pressures for brief pulses are obtained over both space and time to allow evaluation of the absorption coefficient as a function of angle of incidence. When averaged over angle of incidence, this function leads to an average absorption coefficient. Average coefficients were obtained for samples of two different materials. These coefficients, for a pulse two cycles long at 2000 cps, are 0.56 and 0.182. Comparable values computed from impedance tube data are 0.57 and 0.186; and values obtained from reverberation chamber measurements are 0.57 and 0.130. In each case the three values for each material lie within the estimates of error assigned. It is concluded that while the pulse method is confined to short pulses having relatively wide frequency spectra, the method is useful both in producing values of sound absorption coefficients as a function of angle of incidence and of average values of these coefficients.
Attenuation of Ultrasound in Aqueous Suspensions
Authors: Stakutis V. J. , Morse R. W. , Dill M. , Beyer R. T.
Published: September 2005

Measurements of the attenuation of ultrasound in suspensions of lycopodium spores and of a quartz sand are reported. The measurements were made by means of a pulse technique in the frequency range 15–30 mc and temperatures between 20° and 60°C and at various suspensoid concentrations. The results compare favorably with the theoretical calculations of Epstein.
Psycho-Acoustics, Applied and Misapplied
Authors: Burris-Meyer Harold , Mallory Vincent
Published: September 2005

The paper is a historical survey of the attempted application of psycho-acoustic phenomena during and immediately after World War II.
Dispersion of Ultrasonic Pulse Velocity in Cylindrical Rods
Authors: Tu L. Y. , Brennan J. N. , Sauer J. A.
Published: September 2005

The velocities of pulsed longitudinal and shear waves in cylindrical rods of aluminum alloy, brass, copper, and steel were measured by using both the pulse echo and pulse transmission methods. It is found that for pulsed longitudinal waves the measured velocity not only depends upon the elastic constants of the medium but also on the ratio between the radius a of the rod and the wavelength λ. When this ratio a/λ is very small the measured velocity approximates the Young's modulus velocity (E/ρ)12. For large values of a/λ the measured velocity approaches the bulk velocity [(l+2μ/ρ]12 where l and μ are the Lamé elastic constants. Where a/λ is in the vicinity of unity, the velocity drops and seems to approach Rayleigh surface wave velocity. This velocity dispersion effect was not observable when pulsed shear wave was used instead of longitudinal waves. A qualitative explanation for the increase of the measured pulse velocity when a/λ is large based on the equations of motion was given.
An Air Damped Artificial Mastoid
Authors: Weiss Erwin
Published: September 2005

An air damped artificial mastoid has been constructed to simulate the mechanical impedance of the human mastoid. Viscoelastic substances extensively used in current mastoid designs are not employed. The instrument is virtually immune to aging effects and can be easily reproduced. The instrument is used as a laboratory standard to determine the force transmitted through the skull by bone vibrators used in clinical audiometers and bone conduction type hearing aids.
Post-Tetanic Potentiation in the Middle-Ear-Muscle Acoustic Reflex
Authors: Simmons F. Blair
Published: September 2005

Temporary improvement in the threshold of the middle-ear-muscle reflex in response to sound occurs following short exposures to moderately loud sound (80–90 db). Pre- and postexposure reflex thresholds for several frequencies were obtained from awake cats with permanently implanted electrodes in the tensor tympani and stapedius muscles, and on the round window. The increased threshold sensitivity observed (up to 40 db) is considered to be classifiable a phenomenon of post-tetanic potentiation, and as a demonstration of hyperexcitability in certain brain-stem auditory structures following sound stimulation.
On the Mathematical Theory of Woodwind Finger Holes
Authors: Benade A. H.
Published: September 2005

The acoustical effects of open and closed finger holes on woodwind bores in the lower two playing registers are investigated in a mathematical formulation which permits a coherent and comprehensive understanding of the interaction of holes with the bore of a woodwind. Results are expressed in a way which permits accurate engineering calculation of all effects which are discussed. It is shown that when the holes are closed at their outer ends, the system is simply and accurately representable by an adaptation of standard transmission line theory for a tube with side branches. Interestingly, this representation is only possible for musically usable hole sizes and spacings. A related formulation is also possible for a sequence of open finger holes: once again the accuracy of the formulation is greatest for musically usable holes. The part of a woodwind bore that is provided with closed side holes functions as a low-pass filter. Similarly the open holes lower down on the bore function as a high-pass filter. The positions of both cutoff frequencies depend end critically upon the hole sizes and spacings. Both fall at frequencies which allow them to play a role in the tune production. Methods are given for calculating “end corrections” for bores with some open and some closed holes as well as for bores with perturbations to the bore cross section. The effects of “misplaced” or “mis-sized” holes are investigated by these methods, and the position of the lowest open hole calculated. An estimate of the errors in these calculations shows them to be essentially exact for musical purposes. The radiation behavior of a row of open finger holes is analyzed. Frequencies below the “cutoff” of the open hole system are radiated essentially isotropically, while each of the higher components is emitted with its own pattern, all of which are roughly conical, in analogy with the shock wave produced by a supersonic projectile. The musical implications of this are discussed briefly. Light is shed on the function of the bell on woodwind instruments, and on the reason why a bell is not needed on certain of them. The dominant rule of the “closed hole” properties of a bore with finger holes is stressed throughout the paper.
Survey of Flux-Responsive Magnetic Reproducing Heads
Authors: Kornei Otto
Published: September 2005

A magnetic reproducing head which generates signal voltage substantially proportional to the magnitude of the intercepted magnetic flux is commonly referred to as a flux-responsive or magnetostatic head.

The fundamental mode of operation, the different approaches to practical solutions, and the characteristic features of this type of head are described. The explanations are illustrated by a number of cases which have been either proposed or practically executed by various organizations and investigators. References are given, including brief abstracts of pertinent patents and other publications.
Concerning the Noise of Turbulent Jets
Authors: Powell Alan
Published: September 2005

The suggestion that the noise generators of turbulent jets undergo convection effects which are limited in such a way as to follow a similarity behavior leads directly to a resolution of Lighthill's paradox, namely, the problem of accounting for the noise power depending upon the eighth power of the jet velocity simultaneously with the gross directional bias. This hypothesis shown to be at least plausible to a first approximation owing to the general velocity field of the jet having typical dimensions comparable to a fraction of a wavelength; an important corollary is the expectation of appreciable refraction effects. Aspects relevant to the directional peaks of the higher frequencies being less pronounced and located further from the jet axis, and of the slow frequency rise, are briefly discussed.
Speech Processing by the Selective Amplitude Sampling System
Authors: Spogen L. R. , Shaver H. N. , Baker D. E. , Blom B. V.
Published: September 2005

Selective amplitude sampling is a speech processing technique in which the input speech waveform is sampled at the times of its maxima and minima. The original wave is reconstructed from its samples by means of a box-car circuit followed by suitable filtering. The maxima and minima are determined from the zero crossings of the differentiated speech wave. Center clipping is employed to provide amplitude discrimination and a reduction in the average sampling rate. The intelligibility of speech processed by the system is compared with that for clipped differentiated speech and the original speech. “Quality” tests attempted to measure the ability of listeners to distinguish between words processed by the selective amplitude sampling system and a system in which the original words were filtered to a pass band of 300 to 3000 cps. Distributions were obtained of the sampling role averaged over 1- and 10-sec intervals. Word intelligibility and sampling rate are also related to the degree of center clipping in the sampler. The degree of center clipping is measured in terms of an rms voice to-threshold ratio. The word intelligibility scores on the selective amplitude sampling system had a mean of 93.8% and a standard deviation of 4.3%. In addition, 97% of all the test scores were equivalent to 100% sentence intelligibility. The results of the “quality” tests indicate that at least 36% of the time, the listeners were unable to distinguish between the selective amplitude sampling system and the filtered system. The average sampling rate necessary for 100% sentence intelligibility is approximately 1600 samples/sec. This rate corresponds to an rms voice-to-threshold ratio of 7 db.
Electronic Music Synthesizer
Authors: Olson Harry F. , Belar Herbert
Published: September 2005

The electronic music synthesizer is a machine that produces music from a coded record. The coded record, is produced by a musician, musical engineer, or composer with a fundamental understanding of the composition of sound. The electronic music synthesizer provides means for the production of a tone with any frequency, intensity, growth, duration, decay, portamento, timbre, vibrato, and variation. If these properties of a tone are specified, the tone can be completely described. The advantage of the electronic music synthesizer is that it can produce new and radical tone complexes for musical satisfaction and gratification. The new system does not displace the artist and musician of today. It does not take the place of talent combined with work. The electronic music synthesizer provides the musician, musical engineer, and composer with a new musical tool with no inherent physical limitations.
Application of Cell Models to the Determination of Relaxation Times in Kneser Liquids
Authors: Sittig Erhard
Published: September 2005

The vibrational relaxation times of several simple substances in the gaseous and liquid state are compared with values predicted by a simple cell theory of the liquid. Apart from some scatter of the experimental data, satisfactory agreement is found with the theoretical predictions.
Ultrasonic Attenuation in S.A.E. 3140 and 4150 Steel
Authors: Papadakis E. P.
Published: September 2005

The attenuation of longitudinal ultrasonic waves from 5 to 95 Mc is studied by the pulse technique in blocks of S.A.E. 3140 and 4150 steel to determine the loss mechanism and to find possible methods for precision testing the microstructure of materials. It is found that scattering by the grains in the polycrystalline steel is responsible for the attenuation in tempered structure. The critical quantities are the grain diameter and the average squared fractional variation in the elastic modulus of a single grain. It is found that the attenuation is given within experimental limits in the case of steel with martensitic structure by the expression for Rayleigh scattering derived by Mason and McSkimin for the case of the wavelength much smaller than the grain diameter and by the expression for stochastic phase scattering derived by Huntington for the case of the wavelength to grain diameter ratios between 13 and 3. The value of the average squared fractional variation in the elastic modulus (entering both expressions to the first power) was the one given by Mason and McSkimin for iron crystals. Bainite appears to have a higher value of this quantity. An alternative theory by Lifshits and Parkhomovskii may explain bainite. Tempering removed an elasticity from quenched structures. Suggestions for the exact solution for the attenuation at all frequencies are made, and methods of materials testing to investigate grain size and grain quality are outlines. Diffraction corrections and other items relevant to ultrasonic attenuation measurements are mentioned.
A Difference Limen for Vowel Formant Frequency
Authors: Flanagan James L.
Published: September 2005

Experiments have been conducted to determine difference limens (DL's) for vowel formant frequency. The DL's are obtained from quality judgments on synthetic vowel sounds. The results indicate the maximum accuracy necessary in analyzing the formant structure of spoken vowels and in synthesizing the sounds from the resulting formant data.
Outline of the History of Flexible or Elastic Bodies to 1788
Authors: Truesdell C.
Published: September 2005

While several writings purport to give the history of elasticity and vibration, they are so inaccurate or fragmentary as to imply a general picture of the beginnings of these subjects that is outright false. A new history to 1788, drawn from detailed study of all the available sources, is to be published [C. Truesdell, The Rational Mechanics of Flexible or Elastic Bodies, 1638–1788, Leonhardi Euleri Opera Omnia (Ser. II, Vol. 11, Part 2, to appear in 1960)]. The present article provides a list of some of the specific discoveries described therein. The following pages may not conform to the reader's preconception of the subject, or to his idea of what the history of science ought to be. By a one-sided selection of material, or by concentration on a particular problem such as that of the vibrating string, it would easily be possible to write a more inspiring tale of continued progress, or a case study in the development of science. Such a tale, such a study, even if correct in facts would serve only to reinforce all too widely received false pictures not only of how science developed but also of what science is. The problems whose history is outlined here were studied in interrelation to one another, not without steps sideways or even backward, and knowledge concerning them was not gotten in what now seems a logical order of development. This outline is intended for a reader already familiar with the modern theories of elasticity and vibration and already interested in their historical origin; its purpose is to answer for such a person questions of a kind most frequently directed to me, namely, “Who first discovered A?” and “What did B do for acoustics?” It is not, it cannot be a history of the subject. History cannot be understood from precis or digests, however accurate. The reader who desires consecutive explanations, equations, figures, and references may find them in my book. If I were to draw any summary moral from this development, it would be that mathematics was a more powerful tool than experiment in founding the classical theories of elasticity and vibration.
Motion of a Rigid Cylinder Due to a Plane Elastic Wave
Authors: Miles John W.
Published: September 2005

The motion of a rigid cylinder resulting from a normally incident, monochromatic, plane, elastic wave of either P (longitudinal) or S (transverse) type is calculated. Numerical results are presented in the form of curves.
Physico-Chemical Aspects of Chemically Active Ultrasonic Cavitation in Aqueous Solutions
Authors: Lindström Olle
Published: September 2005

Quantitative measurements have been performed on some fundamental phenomena caused by ultrasonic cavitation, i.e., the synthesis of hydrogen peroxide, the oxidation of potassium iodide, the decomposition of carbon tetrachloride, the degassing action, and the evolution of heat in connection with the cavitation process. The experiments were made under controlled and defined acoustic conditions (standing waves, progressive waves, and non-resonance) and the influences by various important factors (acoustic intensity, gas content) have been evaluated.

Tentative theories of the cavitation process and allied phenomena are evaluated on the basis of the experimental results. Cavitation chemistry is found to be similar to gamma radiation chemistry (pH-dependence of the yield of hydrogen peroxide, oxidation of solutes, necessity of oxygen). Cavitation is assumed to be preceded by a homogeneous nucleation process in which a germ or gas nucleus is being formed by rupture of the liquid around this germ. Ionization of some of the gas molecules entrained in the cavity will take place in order to establish the electric charge of the surface of the cavity. Two hydrogen peroxide molecules are formed for every ionized oxygen molecule. It is supposed that in the case of oxygen a cluster is formed by the combination of two water molecules and a positive oxygen ion. This cluster yields on decomposition at the neutralization two hydroxyl radicals and one excited hydrogen perioxide molecule.

The rate of cavitation seems to be independent of (1) the gas concentration (above the threshold concentration), (2) the pressure amplitude (above the threshold amplitude and within the region of cavitation), and (3) the nature of the dissolved gas (provided the gas may initiate homogeneous cavitation at all). These features indicate that properties of the liquid are rate determining when the various threshold requirements are fulfilled. A tentative picture of the nucleation process is presented, which seems to satisfy these conditions.

The degassing action in an ultrasonic field proceeds to half saturation practically independent of the intensity.

A method for cavitation dosimetry is described.
Transient Sound Propagation in a Layered Liquid Medium
Authors: Sherwood J. W. C.
Published: September 2005

A theoretical analysis is made of transient sound propagation between a source and receiver located at arbitrary points in a horizontally stratified liquid medium. Definite integral expressions are developed for an event which has been reflected from, and transmitted through, the interfaces in some designated manner. This event always contains a disturbance which has an onset corresponding to the arrival time predicted by simple acoustic wave theory; for a large horizontal offset of the receiver this arrival may be preceded by a refracted disturbance. The total pressure variation at the receiver, up to some time t, may be ascertained by evaluating all the reflected and refracted events that have onsets preceding t. The employment of a high-capacity digital computer should permit a detailed investigation of problems which involve a few strata only and a receiver offset which is not excessive. It is emphasized, however, that such investigations would involve considerable computing costs, and it is, therefore, economically desirable to incorporate certain approximations into the theoretical analysis.
Attenuation in Shallow-Water Propagation Due to an Absorbing Bottom
Authors: Kornhauser E. T. , Raney W. P.
Published: September 2005

The attenuation of normal modes in a two-layered fluid medium due to absorption in the lower semi-infinite layer is calculated under the assumption that this absorption is small. The result obtained gives the attenuation coefficient for each mode as the product of the absorption coefficient for plane waves in the absorbing layer and a dimensionless function of wavelength and layer depth. Curves of this dimensionless function are plotted for the first five modes in cases typical of propagation in shallow water over a sand and a mud bottom. The results indicate a very rapid decrease in attenuation as the frequency rises above the cut-off frequency, where it is just equal to the bottom absorption. At higher frequencies the attenuation varies as (n2λ3/H3)α, where n is the mode number, λ the wavelength, H the water depth, and α the absorption coefficient in the bottom (α may itself be a function of frequency). The latter result is also derived by a less rigorous method.
Method for Measuring Attenuation of Ultrasonic Longitudinal Waves in Plastics and Rocks
Authors: Auberger Michel , Rinehart John S.
Published: September 2005

An extension of Hughes pulse technique is described for measuring attenuation of ultrasonic longitudinal waves in plastics and range: 250 kc–1000 kc.
Nonspecular Reflection of Sound from a Sinusoidal Surface
Authors: Heaps H. S.
Published: September 2005

The acoustical radiation scattered from a sinusoidal surface of zero pressure insonified by an obliquely incident plane wave of sound is obtained as an infinite series of waves whose coefficients may be determined by means of a recurrence relation. The corresponding analysis is presented for the case of a spherical source of radiation. At points sufficiently remote from the surface only a finite number of terms need be included. Each coefficient in the series is itself an infinite series which converges most rapidly when the height of the surface corrugations is small compared to the wavelength of the incident sound. Application is made to determine the average intensity and fluctuation of the sound reflected from a travelling sinusoidal boundary. The degree of roughness required to destroy the effect of Lloyd mirror fringes is discussed in terms of the ratio of the surface height and wavelength to the wavelength of the incident sound.
Factors Affecting Compressional Wave Velocity in Unconsolidated Marine Sand Sediments
Authors: Brandt H.
Published: September 2005

The influence of porosity, gas content, pressure, and temperature on the compressional wave velocity in unconsolidated marine sand sediments is presented. Velocity behavior is explained from theory. The theoretical behavior is compared with velocity data obtained for sediments in situ and velocity data obtained in the laboratory.

The significant conclusions reached in this study are (1) sediment porosity is the most important factor affecting velocity in unconsolidated water-saturated sand sediments; (2) velocity in a shallow unconsolidated water-saturated sand sediment is nearly independent of the depth of the water above the sediment (within 1% down to a depth of 1000 ft); (3) velocity in an unconsolidated sand sediment is proportional to the velocity in the sea water saturating the sediment; (4) velocity in an unconsolidated water saturated sand sediment increases with an increase in temperature; and (5) velocity in an unconsolidated sand sediment saturated with a mixture of gas and water is considerably lower than the velocity in a sediment saturated with water.
Sound Absorption in the Halogen Gases
Authors: Shields F. Douglas
Published: September 2005

Apparatus has been constructed for measuring sound absorption by the tube method in corrosive gases at high temperatures. This apparatus has been used to measure sound absorption in chlorine, bromine, and iodine vapors at temperatures between 25 and 256°C. The measurements revealed vibrational relaxation absorption peaks in all the gases. In Cl2 the relaxation times varied from 4.90 μsec at 25°C to 1.55 μsec at 255°C. In Br2 the variation was from 0.854 μsec at 28°C to 0.460 μsec at 256°C. In I2 the relaxation time was almost independent of temperature, changing only from 0.106 to 0.102 μsec when the temperature changed from 112 to 253°C.

The heights of the absorption peaks were adequately predicted by assuming the relaxing vibrational specific heat to be Cp−72R. Neither the Schwartz-Herzfeld nor Cottrell-Ream theoretical equations for the relaxation time accurately predict the measured variation with temperature, molecular mass and vibrational frequency.
On Webster's Horn Equation
Authors: Weibel E. S.
Published: September 2005

A wave equation for the sound propagation through tubes is derived by means of Hamilton's variational principle. It is assumed that the wave fronts can be approximated by surfaces of constant stream potential; this is the only assumption made. The variational principle ensures that the best equation that is compatible with this assumption will be obtained. The equation has the form of Webster's horn equation, however its coefficients are defined differently.
Solid Cone in Longitudinal Half-Wave Resonance
Authors: Ensminger Dale
Published: September 2005

Formulas have been derived for determining particle velocity, particle velocity amplification, stresses, length, and mechanical impedance of sections of solid cones—lateral dimensions small compared with the wavelength—in longitudinal half-wave resonance. Unlike the velocity amplification factor of the exponentially tapered bar, that of the conical section does not approach infinity but approaches a limit as the ratio of end diameters approaches infinity. A sample calculation shows the maximum velocity amplification possible from a conical section of steel half-wave resonant at 20 kc to be approximately 4.61 as compared with Merkulov's calculated limit of approximately 4.6.
Independence of the Masking Audiogram from the Perstimulatory Fatigue of an Auditory Stimulus
Authors: Egan James P.
Published: September 2005

The loudness of a steady auditory stimulus declines during the first few minutes of the application of that stimulus. This decrease in loudness is so great that it is important to know whether or not the masked threshold also changes during the initial period of stimulation. In the present investigation the degree of perstimulatory fatigue and the amount of masking were both determined for the same stimulus. It is shown that the masked threshold is essentially independent of the duration of the masking stimulus.
Spread of Perstimulatory Fatigue of a Pure Tone to Neighboring Frequencies
Authors: Thwing Edward J.
Published: September 2005

When a fatiguing tone is presented to one ear of an observer, and, after a period of time, a comparison tone of the same frequency is also presented to the other ear, the intensity of an equally-loud comparison tone is considerably less than the intensity of the fatiguing tone. This phenomenon has been referred to as perstimulatory fatigue. The present investigation was designed to determine the extent to which the perstimulatory fatigue induced by a pure tone spreads to neighboring frequencies.

Perstimulatory fatigue was measured by means of a series of simultaneous dichotic loudness balances made prior to, during, and subsequent to stimulation by a fatiguing tone of 1000 cps at a SPL of 80 db. Test tones were the same in sound pressure as the fatiguing stimulus. When measuring fatigue at a frequency other than that of the fatiguing tone, the fatiguing stimulus was turned off for a 15-second interval. During this interval, a loudness balance was made at the frequency of the test tone.

The findings demonstrate that maximum fatigue is produced at the frequency of the fatiguing stimulus. Fatigue falls off rapidly on both sides of this frequency at a negatively accelerated rate until at 100 cps and at 2500 cps little or no effect is evident. The gradients of perstimulatory fatigue are nearly symmetrical when plotted on a log-frequency scale.
Theory of Oscillation of a Viscoelastic Fluid in a Circular Tube
Authors: Thurston George B.
Published: September 2005

The hydrodynamic theory for the axial sinusoidal oscillation of a viscoelastic fluid in a rigid tube of infinite length and circular cross section is given. The fluid is assumed to be incompressible. Its properties in sinusoidal shear are described by a complex coefficient of viscosity. An equation for the velocity profile is developed and typical profile curves are presented. Equations for the acoustic impedance per unit length of tube are also obtained. Functions from which the acoustic resistence and reactance are directly obtainable for a wide range of the physical parameters are determined and are presented in graphical form. Viscoelastic media which range from a perfect viscous fluid to a perfect elastic solid are treated.
Scattering of a Plane Longitudinal Wave by a Spherical Fluid Obstacle in an Elastic Medium
Authors: Einspruch Norman G. , Truell Rohn
Published: September 2005

The method of Ying and Truell for studying the scattering of longitudinal elastic waves by spherical obstacles is applied to the particular case of scattering by a fluid-filled cavity that is embedded in an isotropic elastic solid. Exact solutions for the expansion coefficients which describe the scattered elastic wave are obtained. The limiting case of ka≪1 (Rayleigh scattering) is considered in detail. A general expression for the scattering cross section is derived.
Acoustical Design and Performance of the Stratford (Ontario) Festival Theatre
Authors: Tanner Robert H.
Published: September 2005

The Stratford (Ontario) Shakespearean Festival has had a record of continuing success since it was started six years ago in a unique theater tent. Since then, the festival authorities have built a new permanent theater retaining the unusual stage and general seating arrangements which combined the Greek and Elizabethan architectural traditions. The shape of the theater and, in particular, the use of a semicircular rear wall centered in the middle of the acting area, presented certain obvious acoustical problems. This paper describes the means taken to overcome this difficulty together with the results obtained.
Duration and Intensity as Physical Correlates of Linguistic Stress
Authors: Fry D. B.
Published: September 2005

The experiments reported in this paper are an attempt to explore the influence of certain physical cues on the perception of linguistic stress patterns. The material chosen was a group of English words in which a change of function from noun to verb is commonly associated with a shift of stress from the first to the second syllable. Spectrograms were used to determine the vowel duration and intensity ratios which occur in these words and this information was applied in making up a test in which listeners' judgments of stress could be correlated with variations in the duration and intensity ratios. The results of the experiments show that duration and intensity ratios are both cues for judgments of stress and that, in the material studied, duration ratio is a more effective cue than intensity ratio.
Touch-Sensitive Organ Based on an Electrostatic Coupling Device
Authors: Le Caine Hugh
Published: September 2005

A device for coupling generators to sound systems in electric musical instruments is described, particularly in connection with its use in a touch-sensitive keyboard. The construction of such a keyboard is shown to be quite straightforward. Many well-known types of generators and any timbre control system may be used. The musical value of a touch-sensitive action is difficult to assess, but the writer is impressed favorably.
Improved Technique for Detailed Measurements of the Middle Ear Impedance
Authors: Møller Aage R.
Published: September 2005

An apparatus is described for measurement of the acoustic impedance of the middle ear at the tympanic membrane. The measuring technique offers a possibility of studying the fine structure of the middle ear impedance, which contains not a single but several resonance peaks. The method employed makes use of a constant current sound source mechanically fixed to a microphone probe indicator. Both the sound generator and the sound receiver microphone are coupled to a tube which is inserted into the ear. This unit can be fixed directly to the subject's head, thereby eliminating the effect of the subject's movements on the measurements.

The results of measurements on eight normal subjects are presented, in part as impedance, in part as admittance. The admittance is measured for 50 cps intervals in the frequency range from 200 to 2000 cps. The individual spread of data proved to be very great and appreciably greater than the difference between the two ears of a single individual.
Some Sonochemical Reaction Yields
Authors: Weissler Alfred
Published: September 2005

Measurements of the yields of some sonochemical reactions show that the number of molecules produced per unit of energy absorbed is several hundred times smaller than the corresponding radiation chemistry (gamma ray) yields. The ratio of the radical yield to the molecular yield in sonochemistry also is smaller than in a gamma-irradiation reactions, but is approximately the same as in alpha-particle irradiations.
Accurate Coupler Pressure Calibration of Condenser Microphones at Middle Frequencies
Authors: Embleton T. F. W. , Dagg I. R.
Published: September 2005

The technique whereby the reciprocity theorem is applied to the determination of the pressure sensitivities of microphones has been modified to improve the reliability and accuracy of the measurements. Sensitivities are measured in terms of the volume of a cavity, the capacity of a fixed condenser, and the variable setting of an accurate potentiometer. Six different pairs of measurements are made instead of three, which is the minimum possible number: this enables check to be made on the internal consistency of each calibration. The accuracy of the measured sensitivities is estimated to be ±0.05 db on an absolute scale and ±0.03 db relative to each other. This technique has been employed to measure the properties of several condenser microphones of each of three well known types over periods ranging from five months to two years. Results are given for their temperature and pressure coefficients, effective volumes due to nonrigidity of their diaphragms and drift with the passing of time.
Dependence of Acoustic Velocity in Some Aqueous Hydroxide Solutions on Temperature and Concentration
Authors: Marks Graham W.
Published: September 2005

The present work, which deals with acoustic velocity at 500 kc in aqueous solutions of LiOH, NaOH, KOH, and NH4OH and results derived therefrom, follows that which was recently reported concerning solutions of certain sulfates. It was found that the velocity vs temperature curves rise and are displaced toward lower temperatures with increase in concentration. The specific acoustic impedance varies linearly with concentration at 20°C. Adiabatic compressibilities are represented by the empirical 3/2-power law. Results for NH4OH are at variance with those for the other hydroxides. The relative association declines with increase in concentration in solutions of NH4OH whereas it increases for the other hydroxides. From the data the apparent molal compressibilities were computed for the temperature range 15° to 35°C. Based on values of the apparent molal compressibilities at infinite dilution the solvation appears to be about six water molecules per ion.
Effect of Sound Waves on Heat Transfer
Authors: Westervelt Peter J.
Published: September 2005

The suggestion is put forward that the effect of sound waves on heat transfer is dominantly result of the modification of the inner streaming boundary layer which is known to occur when the sound particle displacement amplitude s exceeds in magnitude the acoustic boundary layer thickness δac.
Localization of Sound from Single and Paired Sources
Authors: Sandel T. T. , Teas D. C. , Feddersen W. E. , Jeffress L. A.
Published: September 2005

Three experiments on the localization of air-borne sound are described. They were conducted in an anechoic room and employed an acoustical “pointer” as the subject's method of indicating the direction of the stimulus tone. The pointer was a small loudspeaker carried on a boom which rotated about a vertical axis through the subject's head. This speaker presented a wide-band noise which alternated with the tone to be localized. The switching was transientless and was performed by an electronic gate having a 100-millisecond rise and decay time.

Three small loudspeakers in enclosures, one mounted directly in front of the subject and one 40° to each side, presented the stimulus tones to be localized. In the first experiment the speakers were employed singly. In the other two experiments they were used in pairs. In the second experiment the pairs of speakers were in phase; in the third, they were in phase opposition.

The stimulus conditions of Experiment 2 generate a “phantom source” which appears to lie between the two speakers employed. The predicted location is compared with the subjects' responses.

The stimulus conditions of Experiment 3 generate a phantom source which according to prediction, should lie toward the side opposite to the asymmetrically placed speaker and should move in direction with frequency. This prediction is borne out by the subjects' responses for frequencies where interaural time is the dominant basis for localization.

The results of the three experiments support the conclusion that the localization of tones below about 1500 cps is determined largely by interaural time differences. For frequencies above 1500 cps differences of intensity at the two ears must be the dominant factor, but neither probe microphone measurements nor audiograms for the subjects provided information from which satisfactory predictions could be made.
Physical Equivalents of Spectral Notions
Authors: Trent Horace M.
Published: September 2005

The notion of a Fourier spectral equivalent of an arbitrary function has been known for a long time in its basic mathematical form. Calculations of these spectral quantities are conventionally based on the Fourier integral. It is not so well known that the Laplace transformation also yields a spectral notion of which the Fourier form is a special case. In addition, vibration engineers have made extensive use in recent years of the concept of a shock spectrum. Simple physical experiments are described which yield direct quantitative spectral values at specified frequencies for any of the three spectra mentioned in the foregoing. These equivalents are useful in assigning physical significance to the quantities under discussion.
Phonemic Confusion Vectors
Authors: Moser Henry M. , Dreher John J.
Published: September 2005

Test responses of listeners from 27 countries who were tested over a period of a year and a half on several versions of word spelling alphabets are examined to determine patterns of intraensemble confusion. On the word level, confusion seems to hinge on the accented vowel, and these confusions are stratified according to the articulatory position of the vowel. Greater discrimination for front vowels than for back is noted, as well as diminishing intraensemble confusion from high-to-low-articulatory position. A method for computing confusion vectors is presented along with a rationale for increasing the phonemic stability of any particular set of words.
Some Effects of Velocity Structure on Low-Frequency Propagation in Shallow Water
Authors: Williams A. O.
Published: September 2005

Refractive conditions—variations of the velocity of sound in the water—should alter the pattern of acoustic propagation in shallow water, with respect to the homogeneous case. For small values of H/λ (water depth to acoustic wavelength), wave analysis must replace the more familiar ray treatment. If the bottom material acts like a homogeneous fluid, such changes can be computed, for a certain range of H/λ, by perturbation theory starting from the idealized Pekeris solution. The changes depend on the fractional change of sound velocity (and its structure) and on (H/λ)2. Specific calculations are made for a linear gradient and a simple sound channel, and are, in part, corroborated by a variational calculation. Limitations of the method are stated. If it is further assumed that attenuation of such transmission is proportional to the acoustic intensity near the bottom, downward refraction should lead to attenuation greater than that for isovelocity water. A few comparisons with experiment are presented; agreement is fair.