bluuebunny/crossref_metadata_2025_split huggingface dataset:
Binaural Summation of Loudness
Authors: Reynolds George S. , Stevens S. S. 
Published: September 2005

A stimulus of a given sound pressure sounds louder when it is heard with two ears than when it is heard with only one ear. This fact is demonstrated by a series of experiments designed to quantify the ratio of binaural to monaural loudness at various stimulus levels. The methods used included magnitude estimation, magnitude production, one-vs-two-ear ratio production, monaural-binaural loudness matching, and the cross-modality matching of loudness to the apparent intensity of a vibration.
The results indicate that (1) monaural loudness grows as a power function of sound pressure with an exponent of about 0.54, whereas binaural loudness grows with an exponent of 0.6, and (2) the ratio between binaural and monaural loudness increases as a power function of sound pressure with an exponent of about 0.066. This ratio is 2:1 at about 90 db SPL. At lower levels the ratio is smaller, and at higher levels it is larger.
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.
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.
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.
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.
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.
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.
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.
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.
Instrument to Study Relaxation Rates behind Shock Waves
Authors: Resler E. L. , Scheibe M. 
Published: September 2005

An instrument is described which combines the schlieren technique, a photomultiplier tube and an oscilloscope in a manner that enables one to measure the density distribution behind shock waves (in gases) produced in a shock tube. From these measured distributions one can determine the way in which the gas or gases relax to equilibrium and the time it takes to reach equilibrium after the gas's enthalpy is increased suddenly a calculable amount in passing through the shock wave.
The theory of the instrument is discussed and its predicted performance verified experimentally by measuring vibrational heat capacity relaxation times behind shock waves in CO2 containing water vapor. The instrument in the reported tests demonstrated a sensitivity sufficient to record a change in atmospheric density of 12% over 1-mm distance and a space resolution of the density in the shock tube of 1/10 mm corresponding to times of the order of 1/10 μsec.
Notes on the Exact Equations Governing the Propagation of Sound in Fluids
Authors: Hunt Frederick V. 
Published: September 2005

The assumptions underlying the exact equations of motion for a thermoviscous fluid are reviewed and the complete equations are given, for reference convenience, in both tensor and vector form. The first- and second-order acoustic equations are then exhibited and used to obtain the source terms that account for the generation of vorticity and streaming. In order to preserve a broad base from which to make the approximations appropriate under various circumstances, all terms are retained explicitly including those arising from any functional dependence of the viscosity and thermal coefficients on the state variables.
The distinction between spatial and material coordinate systems is carefully drawn and conversion transforms are derived rigorously and their use illustrated. The general properties of finite-amplitude waves are demonstrated by including the second-order terms in a plane-wave solution of the exact wave equation in material coordinates, with special concern for the effects of large amplitude on speed of propagation and on wave-form distortion.
Sound absorption and dispersion measures for a viscous conducting fluid are analyzed in terms of Truesdell's recent exact solution of the first-order secular equation. These differ characteristically from the corresponding measures predicted for pure relaxation in a two-fluid mixture. It is concluded that a complete and adequate theory of sound absorption and dispersion will need to take into account both relaxation and viscothermal phenomena as well as their interaction, and that until such a general theory is available, the exact theory of viscothermal effects—rather than the crude linear approximation commonly, but inappropriately, called “classical”—should be used in computing the “excess” absorption and dispersion to be accounted for by relaxation processes.
The exact solutions of the secular equation permit a new evaluation, in series form, of the characteristic acoustic impedance for a thermoviscous medium. The notes conclude with a revised account of the spectral character of thermal noise in the acoustic medium based on the quantum hypothesis and a merger of the concepts of architectural acoustics and specific-heat theory.
Heat Conduction Losses in the Acoustic Boundary Layer
Authors: Young James E. 
Published: September 2005

The attenuation resulting from heat conduction of the quasi-plane mode in a cylindrical conduit is discussed in the high-frequency (narrow boundary layer) limit. The heat conduction part of the Kirchhoff losses is derived by means of a volume integral whose physical interpretation can be given.
Preliminary to considering the Kirchhoff case, the heat conduction attenuation of a plane wave is computed to illustrate the use of the integral form.
Finite thermal conductivity of the walls, as it gives rise to attenuation in guided propagation, is also discussed.
Microphone Diaphragm Null Method for Sound Pressure Measurement
Authors: Koidan Walter 
Published: September 2005

A null technique is described for accurately measuring sound pressure with a condenser microphone while its diaphragm is held stationary. The method is particularly useful when it is desirable that the microphone present an infinite impedance to the medium and absorb no energy from the sound field. Sound pressure is determined by means of the electromechanical coupling constant, defined as φ = (p/e)u=0, where p is the sound pressure, e is the alternating voltage applied to the microphone terminals, and u is the volume velocity of the diaphragm. By using this definition, a concise derivation of an expression for φ in terms of measurable quantities is described. The value of φ for two Western Electric Company type 640AA condenser microphones was measured as constant with frequency to within ±0.25 db from 500 cps to 20 kc.
The effect of the finite acoustic impedance of a microphone on the magnitude of the incident sound pressure is calculated in terms of quantities obtained by driving the microphone electrically. The measurement of high sound pressure levels in resonant tubes is also discussed.
Method for Measuring Bulk Modulus of a Liquid Using a Helmholtz Resonator
Authors: Ehlers F. Edward 
Published: September 2005

An analysis is given for a method of measuring the bulk modulus of a liquid by means of a Helmholtz resonator driven by an oscillating diaphragm in the cavity wall. The influence of the pressure transducer on the resonant frequencies is considered. In addition to the bulk modulus, the viscosity can be estimated by measuring the “Q” of the cavity.
One resonator was built, tested, and calibrated. Some difficulty was encountered in measuring resonant frequencies of the fluid-filled cavity at atmospheric pressure because of the formation of vapor bubbles. The results obtained for five common liquids compared favorably with earlier measurements of bulk modulus found in the literature.
This method is especially suitable for measuring the bulk modulus of corrosive liquids since the liquid may be completely sealed in the cavity under pressure and no measuring probes are moved through the liquid.
Probe Microphone Analysis and Testing at High Temperatures and High Intensities
Authors: Goff Kenneth W. , Mercer Derwent M. A. 
Published: September 2005

A probe microphone has been developed suitable for measuring sound fields within such structures as altitude wind tunnels and jet engine test cells. This paper describes the methods of testing and analyzing the instrument. The microphone consists of a 38-in. inside diameter probe tube with a porous metal tip, a condenser microphone, and a spiral resistive termination. It operates at sound-pressure levels up to 170 db with 2% distortion, at ambient pressures down to 0.2 atmosphere, and with probe tip temperatures up to 900°F. The normal incidence response is flat within ±3 db from 10 to 10 000 cps.
An electrical analog of the acoustical system is given as a basis for explaining and predicting the performance of the microphone under varying ambient conditions. It appears that the microphone can be used satisfactorily as a cavity terminated probe microphone for frequencies below the frequency at which the spiral termination ceases to be “anechoic.” The required length of the spiral termination is then determined by the probe-tube length rather than the lowest frequency of interest.
Testing methods and apparatus are discussed, including a high-temperature flow resistance apparatus, a low-pressure test chamber, and a resonant tube device for developing sound pressures up to 175 db with low distortion.
Acoustic Electronic Pulse Equipment
Authors: Skudrzyk Eugen 
Published: September 2005

Detailed information is given for the construction of relatively simple, efficient pulse equipment. The repetition rate of the pulse generator varies between once in 10 sec and 25 000 times a sec with a pulse duration from 13 μsec to 100 msec. Pulses of sinsuoidal oscillations may be generated in the frequency range from 50 cps to 100 Mc. The circuits are free from ringing at frequencies below 5 Mc. The power output for pulses of less than 2-msec duration is between 50 to 250 w at frequencies below 10 Mc. A thyratron stage produces a triggering pulse to activate a monostable multivibrator. The adjustable-width multivibrator pulse passes through a cathode follower and furnishes the screen voltage for the output tube. If the frequency is below a few Mc, the output tube may be used to gate a sinusoidal voltage supplied by a standard signal generator. But for high power or at high frequencies, the output tube is preferably driven as a gated, self-excited oscillator.
The receiving amplifier may be connected in parallel with the output of the pulse generator so that the same transducer can be used as both sound projector and microphone. This amplifier limits the large voltage of the driving pulse and is capable of full sensitivity immediately after this pulse has decayed. Some valuable experiences with acoustic transducers are discussed.
Design and Testing of Earmuffs
Authors: Zwislocki J. 
Published: September 2005

Factors controlling the sound attenuation provided by earmuffs are analyzed and an upper limit is estimated of the attenuation that can be expected from simple earmuffs without sacrificing comfort. Further discussion concerns the best dimensions of the earmuff and what can be achieved by adding one or more Helmholtz resonators.
The sound attenuation provided by two different earmuffs was determined on eight subjects in three sessions with a Békésy audiometer. The experimental procedure is described in detail and the results are analyzed statistically. Special attention has been paid to the changes in the listener's threshold of audibility with increasing experience.