bluuebunny/crossref_metadata_2025 huggingface dataset:
Model Experiments on Sound Propagation in Shallow Seas
Authors: Wood A. B.
Published: September 2005

The experiments described deal mainly with the propagation of continuous waves of a particular frequency, and with the variation of signal strength with the depth of the receiver and the water using “point,” almost nondirectional, transducers. A simple method has been found for lining experimental model scale tanks to make them anechoic at the frequencies considered. It has been demonstrated that temperature changes and surface waves produce marked changes in sound propagation. More important influences, however, appear to be due to the nature of the bottom and the depth of the water.

Point-by-point observations, described in Sec. II of the paper, indicate that multiple reflections between the water surface and a hard reflecting bottom, like steel or concrete, result in the propagation of many of the higher modes or orders of reflection and the records of sound intensity variation from surface to bottom is covered with rubber (equivalent to mud and sand), however, the higher modes are suppressed and the records of surface to bottom intensifies are much simpler, containing relatively few maxima and minima. All these observations are in reasonable accord with either the mode theory or the ray theory.

It has been demonstrated also that the received signal (in all-round transmission and reception) is extremely sensitive to the depth of water. A change of depth of say 5 ft in water of depth 200 ft (full scale) may result in a change of the order of 30 db in received signal.

The distribution of the sound field on the bottom and surface of a water layer has been demonstrated by using sounds of relatively high intensity (Sec. III). Interference patterns form not only on the bottom but also on the surface of the water. A simple “abrasive” method has been devised which provides a permanent record of the sound pattern on the bottom.

A new scanning technique has been developed which gives a complete picture of a sound field of relatively low intensity, in a vertical plane either longitudinal or transverse in the water (Sec. IV) . In this method “point” transducers are used, one of which scans a vertical line several times a second whilst the other travels along or across the tank at a predetermined depth. The received signal modulates the cathode-ray oscilloscope spot which moves up and down in synchronism with the scanning transducer. The scan patterns reveal a striking difference between the two cases of a hard steel (rock) bottom and a rubber covered (mud and sand) bottom. The pattern for a steel bottom is very complex and contains many maxima and minima in each vertical scan. The rubber bottom, on the other hand, provides only a few maxima and minima at each scan. The patterns hitherto obtained are, however, not amenable to mathematical treatment. They confirm and amplify the results obtained by point-to-point methods described in Sec. II.

This method of scanning should prove a useful tool for further studies of low-intensity sound fields in water.
Binaural Listening and Interaural Noise Cross Correlation
Authors: Pollack Irwin , Trittipoe W. J.
Published: September 2005

The identification of different interaural correlations was examined over a range of reference correlations. Interaural correlations were produced by the method of Licklider and Dzendolet in which three independent noise sources were combined into two outputs. The change in interaural correlation (squared) required for 75% correct identification varied from about 0.4 for a reference correlation of 0.0 to about 0.04 for a reference correlation of 1.0.
Acoustic Intensity Fluctuations and Temperature Microstructure in the Sea
Authors: Sagar F. H.
Published: September 2005

The range dependence of variation coefficients has been investigated for each of eight selected experiments performed in New Zealand waters during midsummer for a variety of meteorological conditions. These experiments have employed 1.3-msec pulses of 14.5 kc sound from a projector of variable depth (40 to 100 ft). The pulses have been simultaneously received by a vertical string of six equidistant hydrophones (extreme depths 40 and 165 ft) and the square of the average variation coefficient V for the six hydrophones has been plotted against the range R to test for the eight individual experiments the applicability of the Mintzer fluctuation formula. This predicts for a medium exhibiting temperature microstructure that V2 ∝ R ⋅ f2α2a, where f is the frequency and α and a are, respectively, the rms values of the refractive index and the correlation length of fluctuation in the refractive index. An area was selected where the sea is fed by no rivers of any size, the depth varying with experiment from 40 to 200 fathoms. Drought conditions prevailed over the whole period of the work, and, as far as is known, no confluence of local ocean currents here produces microstructure. The latter if present should presumably be confined to surface layers and be due to diurnal insolation. One has hence selected for analysis those experiments performed during small swell and sea state in. (a) the early morning, (b) hot sunshine during the mid and late afternoons, (c) the mid afternoon during cool days with a completely covered sky, and (d) early evening after hot cloudless days. Close correlation exists between insolation and intensity fluctuations which follow the Mintzer dependence on range and the values of α2a obtained [(5.0–11.0)×10−7] are near the mean value reported by Sheehy (5.0×10−7.

The fact that the Mintzer formula is obeyed by case (b) only and the small values of V and independence of V upon R for the aforementioned conditions (a), (c) and (d) are interpreted to mean a diurnal cycle of growth and decay of insolation-produced microstructure in the surface layers of the sea in summer.
The Decilit: A New Name for the Logarithmic Unit of Relative Magnitudes
Authors: Rao V. V. L. , Lakshminarayanan S.
Published: September 2005

The standard magnitude ratio of 100.1 is accepted as a useful device for the specification of relative magnitudes. The significance of such a standard-magnitude ratio when considered as the basis of a unit is discussed. The name decilit is suggested.
Latent and Residual Effects in Temporary Threshold Shift
Authors: Ward W. Dixon
Published: September 2005

Three experiments designed to examine latent effects of low noise-level stimulation gave completely negative results. It is concluded that noises that do not themselves produce TTS (temporary threshold shift) have no effect on the growth or decay of TTS produced by higher level exposures.
Experimental and Theoretical Investigation of the Magnetic Properties of Iron Oxide Recording Tape
Authors: Daniel Eric D. , Levine Irving
Published: September 2005

Part A gives the results of remanent ,magnetization tests made under ordinary and anhysteretic conditions, and shows that the major anhysteretic properties of a recording tape can be expressed in terms of three easily measured constants. The design of the test equipment is discussed and test results are listed for thirteen representative types of tape. Part B reviews some of the theories of fine particle magnets that can be applied to recording tape, and gives an extensive treatment of remanent magnetization based upon the Preisach diagram. Some aspects of the Preisach diagram treatment may be of interest to workers outside the magnetic recording field. The anhysteretic properties are important in hf biased recording and a second paper describes how these properties can be used to predict certain recording performance characteristics.
Confidence Ratings, Second-Choice Responses, and Confusion Matrices in Intelligibility Tests
Authors: Clarke Frank R.
Published: September 2005

The studies reported in this paper have dealt with the responses of human observers to speech stimuli transmitted in a background of white Gaussian noise. In all cases the listeners attempted to identify the transmitted items and then made a second response in an attempt to convey additional information. It was found that when the listeners were allowed a second-choice identification response, very little information was contained in these responses which was not already contained in the listeners' first identification response. When the second response was a confidence rating, significant amount of information was added to that which was carried by the identification response.

The rating which followed each identification response was assigned by the observers in an attempt to estimate the probability that their identification response was, in fact, correct. For message sets of four items and for sets of sixteen items, it was found that the observers were quite capable of making such estimates over a wide range of speech-to-noise ratios. Their estimates did appear to be affected to some extent by the size of the message set and by the speech-to noise ratio, but this interaction was slight.

The observers' rating responses were used to generate ROC curves. These curves were adequately fit by straight lines when the data were plotted on normal-normal probability paper. Regardless of the size of the message set, all curves, for all speech-to-noise ratios, were fit by a single slope. However, the point at which these curves intersected the abscissa was a function of both variables.

Data from one set of observers in the rating experiments were used in an attempt to predict the performance of a different group of observers whose task was to monitor subsets of messages. While predictions were fairly good, discrepancies were noted. An internal check in the monitoring experiment strongly suggests that these discrepancies arose because of differences between the two groups of observers.
Determination of Piezoelectric Properties as a Function of Pressure and Temperature
Authors: McKinney J. E. , Bowyer C. S.
Published: September 2005

Piezoelectric data on a mixed titanate system (82.0% BaTiO3, 9.1% CaTiO3, 3.6% PbTiO3, and 4.4% TiO2 were obtained with an apparatus intended to measure the dynamic compressibility of materials. The calibration constant, determined from measurements on specimens of known compressibility, involves the piezoelectric and dielectric constants of the ceramics used as transducers. The method is discussed and an operating equation for the apparatus derived. Piezoelectric and dielectric constants have been measured as a function of temperature and pressure over the ranges: −25 to 37.5°C and 0 to 1000 kg/cm2. An apparant phase transition was observed near 5°C. A qualitative discussion of the results is given.
Transient Diffraction of Scalar Waves by a Fixed Sphere
Authors: Barakat Richard G.
Published: September 2005

Diffraction from a fixed sphere is treated as an initial value problem rather than as a boundary value problem. By requiring only boundedness of the diffracted wave potential rather than the stronger Sommerfeld radiation condition, it is shown via use of the Laplace transform and complete inversion integral that the diffracted wave potential consists of the usual steady-state term plus transient terms. The magnitude of the transient terms are governed by β = ka where a is the radius of the sphere and k is the wave number; however, the rate of decay is governed by the dimensionless decay parameter ωt. Both Dirichlet and Neumann boundary conditions are discussed in detail. Finally, the transient force on the sphere is computed in the Neumann case and the behavior examined for the long-wave (β≪1) and short-wave (β≫1) approximations.
High-Frequency Strain Gauge and Accelerometer Calibration
Authors: Nisbet J. S. , Brennan J. N. , Tarpley H. I.
Published: September 2005

A method and apparatus are described for calibrating bonded wire resistance strain gauges in the frequency range from 2 to 20 kc. The gauges are mounted on an electromagnetically excited longitudinally resonant bar whose amplitude of vibration is measured by an interferometer. Results are given for one type of bonded wire strain gauges. Factors affecting the frequency sensitivity relationship of bonded wire strain gauges are discussed. Application for calibration of accelerometers is discussed.
Guided Waves in a Fluid with Continuously Variable Velocity Overlying an Elastic Solid: Theory and Experiment
Authors: Tolstoy Ivan
Published: September 2005

Satisfactory agreement between theory and experiment has been secured for the propagation of very low frequency sound (10 and 20 cps) emitted by a point source in a thick sedimentary layer (607 m) overlying a solid elastic basement. In the theory the sediment is treated as a fluid of sound velocity varying with the depth z like (pz+a)−12, and the basement is represented by a solid elastic half space of Poisson's ratio 14. The wave equation has been integrated numerically on an electronic computer. The physical theory, and, in particular, the interesting coupling effects between sound waves and Stoneley or interface waves are discussed. The experimental procedure was the same as the one used in a previously published account of experiments in a different frequency range. Theoretical predictions of the behavior of the sound field in the range of 1 to 5 km are in substantial agreement with the measurements.
Measurement of the Velocity of Sound in Liquid Argon and Liquid Nitrogen at High Pressures
Authors: Dobbs E. Roland , Finegold Leonard
Published: September 2005

An ultrasonic interferometer, consisting of a barium titanate ceramic cylinder suspended in a high-pressure vessel, has been used to measure the velocity of sound in liquid argon and liquid nitrogen at temperatures near their boiling points and at pressures up to 135 atm. The apparatus is suitable for measurements at much higher pressures, since it is rugged, compact, and has no moving parts. An analysis of the resonances obtained over a frequency range 0.2f0 to 1.7f0 (where f0 is the thickness resonant frequency of the ceramic cylinder) has shown that a simple relation exists between the velocity in the liquid and the zeros of the Bessel functions J0 and J1 for frequencies near 0.5f0 and 1.5f0. The velocity data obtained agree with previous measurements on liquid argon and liquid nitrogen at atmospheric pressure, but show that the velocity of sound in these liquids is not a linear function of pressure, as had been supposed by Itterbeek. Using known density data, the adiabatic compressibility and ratio of the specific heats γ have been found for liquid argon and liquid nitrogen at 90°K. For argon, γ falls slightly from 1.97 to 1.89 as the pressure rises to 135 atm, but for nitrogen γ rises from 1.50 to 1.79 with the applied pressure, suggesting the hindering of intramolecular motions at the higher pressures.
Family of Bars of Revolution in Longitudinal Half-Wave Resonance
Authors: Young Frederick J.
Published: September 2005

Expressions for the velocity potential, velocity transformation ratio, node location, resonant length, stresses, and mechanical impedances are derived for a family of tapered bars of revolution in longitudinal half-wave resonance.
Forced Oscillation of a Spring-Mass System having Combined Coulomb and Viscous Damping
Authors: Levitan Edwin S.
Published: September 2005

The solution for the response of a mass-excited dynamic system influenced by both coulomb and viscous damping has been previously presented. Although a direct mathematical analogy exists between the mass-excited and support-excited systems, there appears to be available no practical compilation of results for the support-excited system, interest which has been heightened by the demands of military installations of delicate electronic equipment. In the present paper, an analytic solution for the response of the support-excited system is presented. The solution to the equation of motion is developed through the application of a Fourier Series to represent the frictional force opposing the relative motion between mass and supporting structure. It is assumed that no stops occur during any portion of the steady-state oscillation. The results are presented in a form convenient for observing the influence of system parameters.
Mechanical Resonance Dispersion and Plastic Flow in Crystalline Solids
Authors: Fitzgerald Edwin R.
Published: September 2005

An explanation is given for the mechanical resonance dispersions observed at audio-frequencies in many crystalline solids. The resonances are considered to result from alternating simultaneous slip occurring on transient slip planes with mean lifetimes of 10−2 to 10−4 sec. The slip along such planes is opposed by displacement-dependent, velocity dependent, and acceleration-dependent stresses. These last two stresses are found to be of magnitudes which can result from the interchange of atoms across a slip plane with a consequent decrease of momentum of the fast moving (slipped) part of the sample undergoing deformation. If the rate of transfer is independent of the slip process, a velocity-dependent (viscous) stress results, but if some of the atoms are induced to transfer as a direct result of the slip itself, then an acceleration-dependent stress is present. These slip planes, because of their sudden formation, short lifetimes, and inertial coefficients, do not contribute to the static or ultrasonic compliance, but do affect the dynamic compliance at audio frequencies. The transient slip planes are supposed to be generated by the movement of dislocations across the sample. Thus, a concept of combined consecutive and simultaneous slip is suggested in which dislocations remain an essential part of the mechanism but are not the sole source of deformation. An interesting consequence of the theory is that a critical stress for plastic flow or, alternatively, for brittle fracture can be predicted from values of the dynamic compliance (or modulus). Predicted values of critical stress (for both single crystals and polycrystalline metals) made from the dynamic modulus at 100 cps are much closer to the observed values than those made on the basis of either the static or ultrasonic moduli. In particular, it is found that the predicted values for brittle fracture stress agree almost exactly with observed breaking stresses for single crystals of sodium chloride, germanium, glycine sulfate, and, at two temperatures and orientations, for natural quartz crystals. The occurrence of negative absorption or induced emission is discussed, and a means of generating sustained, self-excited, audio-frequency oscillations in a crystalline solid is outlined. The possibility of mechanical failure at an intrinsic material resonance is considered briefly and some other aspects of the mechanical behavior of crystalline solids are also examined.
Effect of Rain upon Underwater Noise Levels
Authors: Heindsmann T. E. , Smith R. H. , Arneson A. D.
Published: September 2005

Measurements during two heavy rainstorms through an off-shore calibrated hydrophone system showed an increase of up to 25 db in the 20 to 20 000 cps band pressure level as compared to the ambient level before and after. During the period of heaviest rainfall the pressure spectrum level was approximately constant at −23db//1 dyne/cm2 from below 1 kc to above 10 kc, and apparently extends to beyond 40 kc. The pressure spectrum level of the ambient noise can be calculated from the wind force and from a reasonable estimate of the intensity of rainfall.
Mechanical Impedances for Thin Plates
Authors: Thomas Dan A.
Published: September 2005

Boundary conditions are applied to the solution of the thin-plate wave equation using Mindlin's consideration of the effects of rotary inertia and transverse shear flexibility to obtain an improved expression for outgoing flexure waves in an infinite, thin plate. This solution is used to obtain improved expressions for the distributed mechanical impedances and the driving point impedance of the plate. For very thin plates these expressions reduce to those previously published.
On the Pitch of Periodic Pulses
Authors: Flanagan James L. , Guttman Newman
Published: September 2005

Subjects adjusted the frequency of one periodic pulse train to match the pitch of another train fixed in frequency. Two modes of pitch perception are found. In the first mode, for pulse rates less than 100 pps, the pulse trains are ascribed a pitch equal to the number of pulses per second, regardless of the polarity pattern of the pulses. In the second mode, for fundamental frequencies in excess of 200 cps, the sounds are assigned a pitch equal to the fundamental frequency. Between these frequency regions a mode transition occurs in which the pitch judgments generally fall between the pulse-rate and fundamental-frequency values. Amplitude and phase spectra are computed for the stimuli. The stimuli are studied on an electrical analog of the basilar membrane. Waveforms of membrane displacement and first spatial derivative of displacement are obtained from the analog. An effort is made to correlate the psychophysical results with the displacement and derivative patterns observed on the analog membrane. The two pitch modes are found to be manifested in the mechanical operation of the cochlea.
“Long-Time” Differential Intensity Sensitivity
Authors: Pollack Irwin
Published: September 2005

This note considers the differential intensity threshold made over “long” (12, 1, 3 day. and longer periods) time intervals. Its purpose is to point out experimentally what is obvious from personal experience. When a given sound is repeatedly experienced with no variation, small changes in that sound can be detected even over long time intervals.
On the Stability of a Plane Flame Front in Oscillating Flow
Authors: Markstein G. H. , Squire W.
Published: September 2005

Recent experimental studies revealed a close connection between spontaneous excitation of organ-pipe oscillations by flames propagating in tubes and flame front instability characterized by cellular structure. On the basis of these observations a dominant mechanism of vibratory flame movement is proposed, consisting of the following two steps:

1. As a consequence of acceleration instability, the oscillation of the gas column alternatingly distorts and flattens the flame front, thus creating the observed vibration-induced cell structure.

2. The distortions of the flame front cause in turn periodic changes of flame surface area and therefore of burning rate. Spontaneous oscillations are excited if the phase relation between burning rate variation and pressure oscillation is favorable.

In this paper only the first step is analyzed. The linearized treatment yields stability limits in terms of dimensionless parameters representing amplitude and frequency of gas column oscillation and wavelength of flame front distortion. The properties of the flame front entering into the analysis are the ratio of densities of unburned and burned gases, the burning velocity of the plane flame front, and a characteristic length that determines its stability in the absence of oscillations. Results in qualitative agreement with experimental observations are derived.
Vibrations of Thick-Walled Hollow Cylinders: Approximate Theory
Authors: Bird J. F.
Published: September 2005

This paper presents an approximate theory (with sample calculations) for the thickness eigenmodes of an infinitely long hollow cylinder of arbitrary wall thickness, and subject to a variety of boundary conditions. Beginning with the earlier observation that the coupling between shear and compression waves in the solid wall is weak, a perturbation theory is deduced by which approximate eigenfrequencies can easily be computed by hand, with accuracy better than several percent provided the number of radial nodes is more than a few. The perturbation method can also be used to compute the attenuation of sound in the cylinder wall.
On the Production of Sound by Jets
Authors: Thomas Nigel
Published: September 2005

An analysis of sound production by vortices in air jets is given. Specifically, the flow of air through sharp-edged orifices is considered, and it is shown how the results of Anderson on the excitation of jet-tones under these conditions may be explained. The analysis also covers excitation of resonant cavities by the jet, a phenomenon giving rise to pipe-tones.
Measurement of Difference in Loudness Between Typing Noises
Authors: Abruzzo Joseph
Published: September 2005

It is difficult to ascertain the absolute loudness of typing noise by objective measurement. However, it may be practical to use such measurement to determine the loudness level difference in a comparison of the sounds from two typewriters. The requirements that must be met by an accurate measurement technique depend on the degree of accuracy required. Information pertaining to the accuracy necessary has been obtained by employment of two loudness matching procedures over a period of several months. The purpose of the tests was to determine the difference in sound-pressure level of typing noise necessary to enable a person to identify reliably the louder of two typewriters operated simultaneously in a quiet background. It was found that under the conditions adopted for the investigation, differences in sound-pressure level had to be nearly one decibel before they could be recognized 50 percent of the time.

Characteristics of typing noise other than pressure level are discussed. The opinion is expressed that these will, in many cases, not cause significant measurement error, and that difference in loudness between typing noises can often be measured with practical accuracy by means of a sound-level meter.
The Fusion of Intermittent White Noise
Authors: Symmes David , Chapman Loring F. , Halstead Ward C.
Published: September 2005

Stimulus variables influencing the fusion of interrupted white noise have been re-examined in a single trained observer using repetition rate as the independent variable. Critical auditory decay times have been calculated for all observed fusion thresholds under the assumption that the cue for the perception of minimal flutter is a decay of one detectable step in the loudness of the interrupted signal during the off interval. These critical decay times are satisfactorily described by the value 120 milliseconds (independent of intensity) when the burst duration in the interrupted signal is longer than a critical value (5 milliseconds for this listener), but for shorter burst durations the decay times are much lower and exhibit a relationship to burst duration and intensity. A shift in the population of neural units activated under the latter conditions is postulated as an explanation.

The range of individual differences in flutter fusion thresholds under standard conditions has been examined by the use of a tape recorded test requiring repeated discriminations of interrupted from continuous noise. From a sample of 46 normal individuals a population of threshold scores may be postulated having a mean critical fusion frequency of 82.1 interruptions per second with a standard deviation of 19.4 when the interrupted noise has a sound-time fraction of 0.90 and an intensity of 70 db re 0.0002 dyne/cm2.
Thermal Relaxation Absorption in Ethylene
Authors: Gravitt James C.
Published: September 2005

The thermal relaxation absorption in ethylene at temperatures between 0° and 60°C has been obtained by the Tube method for frequencies between 150 kc and 4 Mc per atm. The relaxation time, the transition probability, and the collision efficiency were determined as a function of temperature. The collision efficiency as a function of temperature seems to follow the simple exponential law : P10α exp(−c/T1/3).
Development of a Quantitative Description of Vowel Articulation
Authors: Stevens Kenneth N. , House Arthur S.
Published: September 2005

A set of parameters that yield a simple yet reasonably accurate description of the articulation of vowel sounds is developed. The articulatory description is potentially useful in a speech band-width compression system based on the coding of articulatory data. The parameters give information on the position of the tongue constriction, the size of the constriction formed by the tongue, and the dimensions in the vicinity of the mouth opening. An electrical analog of the vocal tract is utilized to obtain experimental relations between the articulatory parameters and the formant frequencies. Contours of vowel articulation are derived from these data. The relation of the contours to classical phonetics is discussed.
The Reception of Repeated and Overlapping Speech Patterns
Authors: Black John W.
Published: September 2005

Recorded nonsense syllables (CVC) were fed to the headsets of listeners via two channels simultaneously, a direct line and a line that introduced controlled amounts of delay from 0.130 to 0.33 second. The amount of delay was varied in 0.03-second increments and the effect of this variable upon the reception of the syllables was measured. Although the intervals of delay affected the reception scores differentially, no time of delay in the double presentations yielded intelligibility scores that were higher than the scores obtained through a single, direct playback of the stimuli.
Fluctuations of Sound Reflected from the Sea Surface
Authors: Clay C. S.
Published: September 2005

Experimental data on the reflection of sound from the sea surface suggest that the fluctuations of the received signals are due to the scattering of sound from the irregular sea surface. These data are compared with calculations based on the theory of Eckart. A Gaussian correlation function for the sea surface was assumed for the calculations. The scattered sound depends upon the sea surface parameters, source position, receiver position, and acoustic wavelength. The numerical calculations of scattered sound had the same dependence on the source-receiver separation as the experimental data. By using this, the correlation distance and rms wave height are estimated for the sea surface.
Scaling of Pitch Intervals
Authors: Harris J. Donald
Published: September 2005

A literature review showed that in bisecting a musical interval Ss tend to yield the arithmetic mean if the interval is large, but the geometric mean if the interval is small. Since fractionation judgments (“half-pitch”) front which pitch scales may be derived would typically utilize quite hide intervals, and thereby tend to yield the arithmetic mean, a major discrepancy has arisen between such pitch scales and the pitch scale of our musical heritage, which is based upon the principle of the geometric mean. A number of experiments were performed using half-pitch and bisection judgments, and several variants of the method of equal appearing intervals. From these it was concluded that when equal appearing interval judgments are used with a standard interval no larger than about a musical third, a reliable psychological pitch scale emerges which agrees well with the common pitch scale of the piano keyboard. However, if the standard interval is as large as a musical fifth, the pitch scale begins to tend toward that derived from fractionation.
Design of Large Variable Resonant Frequency Transducers
Authors: Fry Francis J. , Dunn Floyd , Fry William J.
Published: September 2005

The transducer design described in this paper employs a mercury column of variable length intimately coupled to an electrically driven piezoelectric element so that a composite vibrating system is formed whose resonant frequency is capable of continuous variation. A large radiating area is realized by combining a number of such composite elements in the form of a matrix. This matrix arrangement is attached to a container which supports the mercury column. One dimension of this column is varied by means of a mechanically driven piston. The entire assembly is enclosed in a steel tank with a sound rubber window to permit its use as an underwater sound transducer.
Note on the Papers: I. “Combined Translational and Relaxational Dispersion of Sound in Gases,” by M. Greenspan; II. “The Effects of Viscosity and Heat Conduction on the Transmission of Plane Sound Pulses,” by J. R. Knudsen
Authors: Jarvis Stephen
Published: September 2005

For the “Becker” gas, the heat conductivity K and viscosities (μ,λ) satisfy K = (2μ+λ)Cp; transient three-dimensional acoustic pressure disturbances are propagated according to a third-order equation derivable from the Navier-Stokes equations.
Electromagnetic Reflection from Sound Waves
Authors: Schmitt Hans J. , Wu Tai Tsun
Published: September 2005

The reflection of electromagnetic waves normally incident on the wavefronts of a semi-infinite standing sound wave in a liquid is discussed theoretically. Since the reflecting planes of maximum sound pressure disappear periodically, the reflected electromagnetic signal is modulated with the acoustic frequency. The modulated reflected electromagnetic wave arises (1) from the microscopic movement of the liquid surface, and (2) from the direct analog of Bragg reflection in optics. The second effect is most pronounced when the wavelength of the electromagnetic radiation in the liquid is twice the acoustic wavelength.
Scattering of Sound by Isotropic Turbulence of Large Reynolds Number
Authors: Ford G. W. , Meecham W. C.
Published: September 2005

Lighthill has given an expression for the intensity of acoustic radiation scattered from turbulent fluids. He finds that such scattered energy is proportional to the square of the Mach number of the turbulence and is also proportional to the value of the turbulence spectrum function at wave number equal to the magnitude of the change in the wave vector during the scattering. If it is supposed that the turbulent region has a Reynolds number sufficiently large to give rise to an inertial subrange, one can use similarity principles to obtain information concerning the spectrum of the scattered radiation. This is accomplished by the use of a Lagrangian-type of space-time velocity correlation in order to treat properly convective effects of the macro-eddies. The result is that the position of the maximum of the scattered power spectrum is shifted from the incident frequency by an amount determined by the Doppler shift due to the mean flow. The half width of the spectrum is proportional to the turbulence Mach number. The maximum of the spectrum is also proportional to the turbulence Mach number and to (ω0)−23, where ω0 is the angular frequency of the incident wave.
Interference Patterns in the Near Field of a Circular Piston
Authors: Dehn J. T.
Published: September 2005

A number of ultrasonic ring patterns, recorded photographically in the near field of a circular piston, are presented as the principal feature of this paper. In appearance they resemble the diffraction patterns of light in front of a circular aperture which appear in most textbooks on physical optics. First, the method of recording is commented upon. Then the positions of the central maxima and minima are shown to agree with the predictions of wave theory. And finally, a simple ray theory, based on a method first proposed by Schoch and capable of giving a qualitative picture of the field in front of the piston, is discussed.
Tank Wall Lining for Underwater Sound Use
Authors: Tamarkin Paul , Eby R. K.
Published: September 2005

An anechoic lining for underwater sound use can be made from waterproofed, rubberized, horsehair batting. It decreases the reflectivity 20 db below that obtained from a steel wall over a frequency range from 100 kc to 400 kc and for a wide range of angles of incidence. It is inexpensive, easily installed, and can be used for several 8-hour periods before additional waterproofing is necessary.
Corrected Values of the Elastic Moduli of Sapphire
Authors: Mayer Walter G. , Hiedemann E. A.
Published: September 2005

Corrected values of the elastic moduli of sapphire are given based on earlier work of the authors but using more accurate crystal orientations.
Effects of Dynamical Nonlinearity on Extremal Statistics
Authors: Smith D. A. , Lambert R. F.
Published: September 2005

Experimental studies of the probability distribution of strain extrema resulting from nonlinear random vibrations of an elastic bar are here reported. The distribution of extrema are found to deviate from a Rayleigh distribution which holds experimentally for linear motion. Of particular interest are large strain levels where the distribution of maxima fall above a Rayleigh distribution while the minima lie below.
Wave Propagation in Elastic Tubes Filled with Streaming Liquid
Authors: Morgan G. W. , Ferrante W. R.
Published: September 2005

A theoretical analysis of the propagation of pressure waves through elastic tubes filled with streaming incompressible viscous liquid is presented. The limiting results for the case of vanishing viscosity are compared with those for an inviscid liquid. The influence of the steady stream upon which waves are superposed, of wall inertia, and of Poisson's ratio are discussed. The analysis is restricted to tubes with thin walls, to waves whose amplitude is small and whose wavelength is large compared to the radius of the tube, and to liquids with sufficiently small viscosity.
Some Developments in Vibration Measurement
Authors: Edelman Seymour , Jones Earle , Smith Ernest R.
Published: September 2005

This paper describes cemented barium titanate accelerometers of two simple types, an electromagnetic shaker with a symmetrically mounted shake table, a set of barium titanate shakers, and two optical methods of accelerometer calibration, one using a microscope with a stroboscope of wide frequency range and one using a Fizeau type interferometer. Calibration results from 50 to 11 000 cps are given.
Simple Triggering and Marking System for Measuring Shock-Wave Velocities in Tubes
Authors: Thurston Edward G.
Published: September 2005

A system consisting of specially designed pressure switches and a simple associated circuit is described for measuring the velocity of propagation of shock waves in tubes.
Sound Field of a Rectangular Piston
Authors: Freedman A.
Published: September 2005

The amplitude and phase of the pressure in the field of a rectangular piston, assumed vibrating within an infinite, rigid baffle, are examined theoretically for ranges down to the order of the piston length. Various laws of behavior of this field, both on and away from the acoustic axis, are deduced. An indication is given of the errors introduced by the approximations used. Such experimental evidence as is available supports the theory.

Simple means are provided for constructing curves of axial pressure amplitude and phase for any ratio of length to breadth of the radiating surface, and a method is suggested for predicting the long-range axial pressure of a rectangular piston from measurements taken well within the latter's Fresnel region.

The near fields of a rectangular and a circular piston are compared. That of the rectangular piston produces the more useful approximation to a plane wave.
Theory for Pitches 19, 15, and 11 Plus a Rumbling Resulting from “sin 19x+sin 15x”
Authors: Meyer Max F.
Published: September 2005

An old and revived graphical method is applied to the hydraulic theory of cochlear mechanics.
Some Parameters Influencing the Pitch of Amplitude Modulated Signals
Authors: Small Arnold M.
Published: September 2005

The rise-fall time, duty cycle, and carrier frequency of a pulsed tone were systematically varied. Listeners matched the pitch of this signal to that of a sinusoidal comparison tone. Low SPL was used throughout. Two pitches were identified, one corresponding to the repetition rate (periodicity pitch), and the other to the carrier frequency (carrier pitch). The periodicity pitch decreased in audibility with the increase of any of the experimental variables. These variables had the opposite effect on the perception of the carrier pitch, which in general was audible only at the longer duty cycles. Individual listeners varied considerably in their ability to match the pitch of the pulsed tones. Comparison of the results obtained with pulsed sinusoids to those of pulsed noise suggest that the perception of a periodicity pitch depends upon the band width and spectral location of the pulsed signal's frequency components as well as envelope wave form fluctuation.
Acoustic Loci and Transitional Cues for Consonants
Authors: Delattre Pierre C. , Liberman Alvin M. , Cooper Franklin S.
Published: September 2005

Previous studies with synthetic speech have shown that second-formant transitions are cues for the perception of the stop and nasal consonants. The results of those experiments can be simplified if it is assumed that each consonant has a characteristic and fixed frequency position, or locus, for the second formant, corresponding to the relatively fixed place of production of the consonant. On that basis, the transitions may be regarded as “movements” from the locus to the steady state of the vowel.

The experiments reported in this paper provide additional evidence concerning the existence and positions of these second-formant loci for the voiced stops, b, d, and g. There appears to be a locus for d at 1800 cps and for b at 720 cps. A locus for g can be demonstrated only when the adjoining vowel has its second formant above about 1200 cps; below that level no g locus was found.

The results of these experiments indicate that, for the voiced stops, the transition cannot begin at the locus and go from there to the steady-state level of the vowel. Rather, if we are to hear the appropriate consonant, the first part of the transition must be silent. The voiced stops are best synthesized by making the duration of the silent interval equal to the duration of the transition itself.

An experiment on the first formant revealed that its locus is the same for b, d, and g.
Comparison of Objective and Subjective Observations on Music Rooms
Authors: Blankenship Joseph , Fitzgerald R. Bernard , Lane R. N.
Published: September 2005

This paper presents a comparison of the physical and acoustic measurements in several music rooms at The University of Texas with the subjective reactions of the musicians working in these spaces. Emphasis is placed on the musicians' viewpoint in regard to desirable room characteristics.
Variation in Ear Protector Attenuation as Measured by Different Methods
Authors: Weinreb L. , Touger M. L.
Published: September 2005

The ASA standard “Method for the measurement of the real-ear attenuation of ear protectors at threshold”—Z24.22/406, specifies the use of threshold shift techniques. It has been observed in our laboratory during extensive evaluation of developmental ear protective devices over the past ten years that large differences in attenuation are obtained when using different attenuation measuring techniques. In addition, these differences vary for the different types of protectors being studied. In the study reported herein, four grossly different types of protectors were measured. These protectors differ in the volume under the protector and in the principal sound transmission path at low frequencies. The test subjects and room environment were the same for all the measurements. The results indicate that threshold shift measurements yield higher values of attenuation than either loudness balance or the microphone method. However, the results vary widely for different types of protectors as a function of frequency. Differences of 3 db or greater between protector types as measured by any of the three measuring techniques were found to be significant at the 95% confidence level using four subjects and three replications.
Determination of the Recording Performance of a Tape from Its Magnetic Properties
Authors: Daniel Eric D. , Levine Irving
Published: September 2005

This is the second of two papers. The first (I) [J. Acoust. Soc. 32, 1 (1960)] dealt with the general magnetic properties of recording tape. The present paper gives an analysis of hf biased recording based upon the anhysteretic properties of the tape as specified in I. Calculations of performance are compared with the results of absolute measurements carried out on a conventional recording machine and on large scale models. Satisfactory agreement is obtained when the theory is corrected to take into account a loss attributed largely to a dynamic form of demagnetization which takes place during recording. The corrected theory can be used to compare tape performance under a variety of operating conditions without reference to a particular test recorder. Attention is confined to recorded wavelengths which are large compared with coating thickness.
Sound Energy Integrator with an Electrostatic Squaring Device
Authors: Lochner J. P. A. , Meffert P.
Published: September 2005

Investigations of the contribution of short-time delayed echoes to the intelligibility of speech have brought out the fact that reflections arriving within 95 msec after the direct sound in an auditorium have a positive contribution, and, reflections after this period, a negative contribution to the intelligibility of speech.

The instrument described, developed for the analysis of reflection patterns in auditoria, incorporates an electrostatic squaring device and an electronic counter as registration unit. Sound energy can be integrated by means of this instrument over pre determined short periods at any given interval after the direct sound.
Acoustical Propagation of Higher Order Modes in the Region of Cutoff
Authors: Lambert Robert F.
Published: September 2005

Experimental data on the amplitude of transverse particle velocity associated with the (1,0) mode of rectangular tube for frequencies in the region of cutoff are presented. The distance decay from the source is exponential for frequencies investigated in the range f/fc⩽0.998 where f is the frequency of excitation and fc is the mode cutoff frequency. At cutoff, the amplitude drops to the fraction 1/e of its value at the source over a distance interval equal to about 8 times the tube width. For frequencies above f/fc = 1.01 the progressive wave pattern appears fully developed. Comparison data between theoretical and measured values of attenuation for frequencies below cutoff are also presented.
On the Class of “Reciprocity Methods”
Authors: Madella G. B.
Published: September 2005

In addition to the so-called “Reciprocity Methods” for calibrating electroacoustic transducers, other methods are also based upon the reciprocity principle. It is therefore suggested that, at least in theoretical treatments, the modern methods be quoted as a particular form of the more general class of reciprocity techniques.
Ultrasonic Matterscope
Authors: Voutsas Alexander M.
Published: September 2005

This is a review of the work conducted by the author since 1944 on the development of an instrument which, by means of ultrasonics, identifies a material, examines its microstructure and its homogeneity, detects impurities, and predicts its life before destruction. (“Matterscope” is a new word, coined by the author, to describe this instrument; hence the method “matteroscopy.”)
Determination of Finite Amplitude Distortion by Light Diffraction
Authors: Cook Bill D.
Published: September 2005

The theory of a new optical method of determining the harmonic structure of progressive ultrasonic waves undergoing finite amplitude distortion is developed using Fourier transforms. The waveform is determined by measurement of the light intensity of all the orders in the diffraction pattern.
Axisymmetric Vibrations of Shallow Elastic Spherical Shells
Authors: Kalnins A. , Naghdi P. M.
Published: September 2005

This paper contains an exact solution within the scope of the bending theory of shells for axisymmetric vibrations of thin shallow elastic spherical shells. Specifically, the solution is applied to an investigation of the natural frequencies of the free axisymmetric vibrations of spherical shell segments with various edge conditions. Comparison drawn with previously known results for transverse vibrations of shallow spherical shells, where the effect of longitudinal inertia is neglected.
Vowel Synthesis by Means of Resonant Circuits
Authors: Weibel E. S.
Published: September 2005

Various ways of creating artificial vowels are discussed and compared from the viewpoint of coding efficiency. A method which requires seven parameters to specify any vowel is then introduced and described in detail. It is based on the realization of the transfer impedance of a nonuniform transmission line by lumped elements.