bluuebunny/crossref_metadata_2025 huggingface dataset:
Underwater Explosion Shock Wave Parameters at Large Distances from the Charge
Authors: Arons A. B.
Published: September 2005

Experimental observations of peak pressure, decay constant, and energy flux for TNT and pentolite are presented to ranges (in feet) defined by R≅2000W12, where W is charge weight in pounds. Previously published results extended only to R≅30W12.
Ultrasonic Spectrum of Cavitation Noise in Water
Authors: Mellen Robert H.
Published: September 2005

The acoustic noise spectrum associated with the collapse of transient cavities produced by a stirring rod in water was measured in the frequency range 1–3500 kc. While the spectrum, in general, goes as f−2 above 1 kc, flat regions are found between 20 kc and 100 kc, and again above 500 kc to at least 3500 kc. If the flat regions are due to discrete random impulses, two time constants, τ1≃10−6 second and τ2<10−8 second, may be obtained by using the criterion 2πfτ≃1, where f is the −3 db point beyond the flat region.

With intense cavitation, the acoustic level fails off and becomes erratic in the 600-kc region. Transmission measurements made through the cavitating volume show strong sound absorption, which appears to be caused by a cloud of small, stable bubbles.
An Artificial Voice and Miniature Anechoic Chamber for Hearing Aid Measurements
Authors: Carlisle Richard W.
Published: September 2005

There is described an enclosure for a standard loudspeaker mechanism which provides a compact sound source or artificial voice. With a size slightly larger than a human head, the frequency range is 100 to 7000 cps. A simple and reproducible arrangement of damping felt gives unusual flatness.

This artificial voice can either be used in free space or with a small chamber arranged as an acoustic labyrinth, for testing microphones and hearing aids. In the chamber, calibrating microphone is mounted opposite the test microphone for continuous monitoring. Simple rc compensating networks are utilized to equalize the sound source for either free-space or labyrinth measurements.
Responding to One of Two Simultaneous Messages
Authors: Spieth Walter , Curtis James F. , Webster John C.
Published: September 2005

Twenty operators were given a task which required answering one of two simultaneous voice messages. The task was performed under a variety of conditions produced by combinations of four experimental “aid” variables: horizontal spatial separation of the sound sources, aural shaping filters which made the tone quality different in each channel, visual cues which indicated the channel about to call the operator, and facilities to “pull down” a desired message from the initial source into a headphone or a loudspeaker near the operator's ear. It was found that the use of horizontal separation and/or the filtered messages greatly improved the operator's performance. Visual cues had no apparent effect on ability to answer the message except when used with pull down facilities. The pull down facilities aided the operator to some extent. Some speculations are advanced about the nature of recognizing and attending to a message in the presence of another message.
Design of Visible Speech Devices
Authors: Peterson Gordon E.
Published: September 2005

The conventional sound spectrograph affords the analysis of short signal samples and considerable flexibility in the construction of amplitude sections. Other major interests in sound spectrography are in the instantaneous portrayal of signals, and in the permanent record display of continuous linear and logarithmic analyses. This paper suggests instrument methodology for carrying out these operations. Values which are considered practical are suggested for the parameters of certain of the systems which are discussed.
The Electro-Acoustic Sensitivity of Cylindrical Ceramic Tubes
Authors: Langevin R. A.
Published: September 2005

Increasing use is being made of cylindrical barium titanate tubes as underwater acoustic transducers. An exact derivation is given for the low-frequency acoustic sensitivity of such tubes for a variety of boundary and polarization conditions.
An Acoustic Method for the Measurement of Vibration Amplitudes
Authors: Koidan Walter
Published: September 2005

By means of a modification of the pistonphone, a technique has been developed to obtain the response of a capacitance type vibration pickup probe using the reciprocity calibration of a condenser microphone as a reference. The raised, center portion of a circular piston, driven by a barium titanate cylinder, projects into one end of a cavity, the shelf of the piston being located outside of the enclosure. A calibrated condenser microphone coupled to the other end of the cavity responds to the sound pressure developed by the piston. The output of an annular capacitance type vibration pickup, which detects the motion of the piston shelf, is compared with the generated microphone voltage. With the microphone removed from the cavity, the output of a capacitance probe located adjacent to the top surface of the piston is compared with that of the annular pickup. The probe response is computed from these measurements and the microphone response.

From considerations of checks by independent methods, an accuracy of about 0.5 db is indicated from 100 to 10 000 cps. Using a sensitive probe, vibration amplitudes as small as 10−9 cm have been measured with a comparable degree of accuracy.
Logarithmic Measure and the Decibel
Authors: Hall William M.
Published: September 2005

A simple method of expressing the logarithmic measure of physical quantities is proposed, which is generally applicable to all quantities and avoids the use and misuse of the term decibel.

Editor's note.—It is believed that discussion and critical thought on this subject should be encouraged. and it is to this end that this Letter is published. The Editors do not necessarily concur with the views expressed.

The definition of the decibel and related units will be studied during the forthcoming revision of American Standard Acoustical Terminology Z24.1-1951 by Sectional Committee Z24. Suggestions (especially in the form of preferred wordings of definitions) are welcomed; address proposals to Chairman of Writing Group Z24.W-5, Robert W. Young. U.S. Navy Electronics Laboratory, San Diego 52, California.
Magnetic Dispersion and Attenuation of Sound in Conducting Fluids and Solids
Authors: Alpher Ralph A. , Rubin Robert J.
Published: September 2005

It is shown that the general treatment by van de Hulst of the dispersion and absorption of sound arising from mechanical-electromagnetic coupling in conducting fluids immersed in magnetic fields applies directly to conducting elastic solids.
The Acoustic Resistance of a Pipe Orifice to Steady-State Fluid Flow
Authors: Wood John K.
Published: September 2005

Steady-state flow data for a viscous, incompressible fluid are plotted as acoustic resistance against volume velocity extended to a volume velocity corresponding to a Reynolds number of one. The acoustic impedance at zero frequency is then equal to the resistance predicted from Poiseuille's equation for laminar flow. The value of the Poiseuille resistance depends on the effective length of the pipe which in turn requires a reliable value of the end correction. By using end corrections that have proven adequate for periodic flow, the computed resistance agrees with the experimentally measured resistance in the region where resistance is independent of volume velocity or flow for orifice diameters from 0.106 cm to 1.28 cm. The resistance vs flow curve has a bend point at a Reynolds number of about ten for all orifice diameters measured. The resistance depends on the flow beyond a Reynolds number equal to ten, increasing with constant slope.
Elastic and Anelastic Behavior of Some Metals at very Low Temperatures
Authors: Bordoni Piero Giorgio
Published: September 2005

Vibration frequency and damping have been measured as a function of temperature in the range 4.5°K–300°K, for lead, copper, aluminum, and silver rods. Damping has been found to reach a maximum near 13 of Debye temperature, owing to a new relaxation effect. Near the absolute zero both damping and frequency changes vanish as a high power of temperature.
Acoustic Impedance of a Right Circular Cylindrical Enclosure
Authors: Biagi Fernando , Cook Richard K.
Published: September 2005

At low frequencies, the acoustic impedance of a right circular cylindrical enclosure (containing air, or other gases) is affected by the cooling effects of the walls. Analytical expressions for the temperature distribution have been obtained, and computations of the effect on the impedance are given in the form of plotted correction factors. These corrections are used in making absolute pressure calibrations of condenser microphones at low frequencies.

The solution presented for the average temperature distribution applies also to the heat-conductivity problem of a uniform volume distribution of sinusoidal heat sources, which are considered to be in phase, inside a cylindrical enclosure having isothermal walls.
Transverse Vibrations of a Symmetric Tapered Reed
Authors: Leitner A. , Hiedemann E. A.
Published: September 2005

The tapered reed, used in ultrasonic whistles, is a symmetric and homogeneous bar of rectangular cross section, uniform in the center and uniformly tapered to a sharp edge at each end. It is vibrating transversely under free-free conditions in the plane of the taper, and in its lowest symmetric mode; i.e., it must be mounted at the nodes. We have calculated the frequencies and positions of the nodes for such bars, combining the exact methods of Rayleigh and Kirchhoff for bars of uniform and tapered cross sections, respectively. The main problem is that of joining the two different solutions at the junction of the two regions. Results were obtained for a representative range of values of the ratio of length of tapered portion to total length. The effect of the surrounding medium has not been considered.
Intelligibility of Different Speech Materials
Authors: Hirsh I. J. , Reynolds Elizabeth G. , Joseph Maurice
Published: September 2005

Articulation scores for nonsense syllables and for monosyllabic, disyllabic, and polysyllabic words were obtained as a function of the cut-off frequency of low-pass and high-pass filters and also as a function of signal-to-noise ratio at different noise levels. Results indicate that eliminating all frequencies above or below 1600 cps does not impair the intelligibility of words seriously. The intelligibility of a word is a direct function of the number of syllables in the word and monosyllabic words are more intelligible than nonsense syllables. The relation between the intelligibilities of each word type and nonsense syllables is not the same when the system is impaired by filtering as it is when the system is impaired by noise. The implications of the lack of consistency from one experiment to the other for the generality of the concept of articulation index is discussed.
Short-Term Autocorrelation Analysis and Correlatograms of Spoken Digits
Authors: Biddulph R.
Published: September 2005

Autocorrelation techniques provide a method of displaying speech sounds in a form which differs significantly from conventional sound spectrograms. The autocorrelation function ψ11(τ), of a signal I(t) is defined by ψ11(τ) = LimitT→∞1T ∫ 0T I(t)I(t-τ)dt. Delay τ introduced in the speech signal appears as ordinate in these displays, time t as abscissa, and magnitude of the resulting correlation function ψ11(τ) is shown by the density of the pattern. Characteristic features of the displays are discussed and evaluated in terms of the mechanism of the correlation process. Data considered are limited to the ten spoken digits one, two, ⋯ nine, “oh.”
Some Further Experiments upon the Recognition of Speech, with One and with Two Ears
Authors: Cherry E. Colin , Taylor W. K.
Published: September 2005

The experiments described here continue a series reported in this Journal earlier. A number of objective tests are described, directed towards the general problem concerning the faculty we possess of perceiving only one acoustic world under normal conditions (in spite of having two ears) and yet, if our ears be stimulated by different signals, artificially, we can attend to one or the other of them. The tests have been made with continuous speech (readings from light fiction) and the results assessed statistically. The first tests aim at measuring the reaction time r required to “switch the attention” from one ear to the other, as assessed by perception of the words of the message. A second set of tests show that we perceive only one speaker, as a “gestalt,” when the ears are stimulated by similar messages but with a delay between them exceeding 20 times that ever experienced in real life by virtue of binaural directivity.
Absorption and Dispersion of Ultrasonic Waves in Liquids
Authors: Parthasarathy S.
Published: September 2005

Mr. Chairman and Friends: It gives me great pleasure to be amongst you on this great occasion when you are celebrating the Silver Jubilee Anniversary of the Acoustical Society of America. This has been made possible by the invitation extended to me by the Society and by the Government of India's deputing me to attend the function. It is indeed a pleasant duty to thank both the Acoustical Society of America and the Government of India for their generous gestures. And hereby I convey the greetings of India!

The subject I have chosen for a talk on this occasion is “The Absorption and Dispersion of Ultrasonic Waves in Liquids,” a subject in which I have been greatly interested in the past few years.
Loudspeaker Accessory for the Production of Reverberant Sound
Authors: Martin Daniel W. , Knoblaugh Armand F.
Published: September 2005

Organ music produced in small rooms having little natural reverberation can be enhanced by the addition of artificial reverberation. A direct method of adding the aftersound at the electroacoustic transducer itself is described. This is in contrast to the more conventional reverberation systems employing driving transducers, time-delay means, pickup transducers, and mixing and amplifying circuits. Multiply resonant helical mechanical delay lines store the energy and radiate it at a later time. In one model the coupling to the transducer is mechanical, and in the other model acoustical coupling provides a number of practical and acoustical advantages.
The Response of Earphones in Ears and Couplers
Authors: Burkhard Mahlon D. , Corliss Edith L. R.
Published: September 2005

Applied voltage responses of seven earphones both ears of fourteen people were obtained with the aid of a probe tube microphone inserted into the volume enclosed by the earphone. Treatment of the response data by the method of analysis of variance allowed separation of variance effects due to error in repeated measurement, dissimilarity between a given person's ears, and differences among individuals. The latter are found to be the most important effects to contend with in audiometric practice. Effects of application force on sound pressure output of an earphone are examined. Comparisons between the average response ears and on three superficially different couplers are presented. Responses ears were substantially different from responses couplers over parts of the frequency range. Recommendations are given for improving the reliability of audiometric measurements by instrumental refinements.
An Experimental Study of Polarization Effects in Barium Titanate Ceramics
Authors: Hueter T. F. , Neuhaus D. P. , Kolb J.
Published: September 2005

The electromechanical coupling in barium titanate ceramics is studied as a function of external bias for thickness resonances in the ultrasonic frequency range. The losses associated with the heating of resonant transducers are shown to be primarily of mechanical rather than dielectric origin. The response near coercive field strengths indicates that the rearrangements of domain patterns take place in at least two separate forms. The relationships of the subsidiary responses, which are observed in ceramics under suitable driving conditions, to the state of internal polarization are discussed. Domain processes of the kind assumed in this study furnish an explanation for the observed constriction of dielectric hysteresis loops.
An Exact Method for Determining the Directivity Index of a General Three-Dimensional Array
Authors: Rhian Elliot
Published: September 2005

An exact method for determining the directivity index of a general three-dimensional array with phased elements is described. The expression for the reciprocal of the directivity factor is shown to be a sum of terms which are simple functions of the sensitivity, phasing, and location of the elements of the array. As an example, the method is applied to a sixteen-element plane array.
The Propagation of Elastic Waves in Thin-Walled Cylindrical Shells
Authors: Junger Miguel C. , Rosato Frank J.
Published: September 2005

This paper presents a study of the propagation of elastic waves in the walls of cylindrical shells. Two modes of propagation in the axial direction are found to exist; at high frequencies, the one corresponds to flexural waves, the other to longitudinal waves. The dispersion curves are in good agreement with published experimental data. Hitherto available analyses are based on the membrane theory of shells, which disregards bending stresses; these analyses lead to partly different conclusions in that they predict a “dead” frequency region where no propagation occurs, and in that they do not account for the high-frequency flexural mode. The discrepancy carries over into the evaluation of the natural frequencies of the tube, and of the dispersion of pressure waves propagating in liquid-filled tubes. Published experimental data on the latter process at ultrasonic frequencies also support the present analysis.

Results of this analysis have been applied to the investigation of the dynamics of barium titanate transducers in the form of cylincrical shells. Some important concepts of sound insulation by lightweight partitions, such as the “coincidence dip,” depend essentially on the ratio of the sound velocity in air to the phase velocity of elastic waves in the partition; the present analysis might therefore also find a practical application in the adaptation of these concepts to cylindrical surfaces, such as the skin of aircraft fuselages or architectural shells.
Unison Tuning of Musical Instruments
Authors: Corso John F.
Published: September 2005

This study deals with two factors related to the unison tuning of musical instruments: (1) the harmonic structure of the reference tone, and (2) the method of presentation of the reference tone during the tuning process. Data are presented on the accuracy of tuning four different instruments in unison with five reference-tone waveforms under simultaneous and successive tuning conditions. The results indicate that neither harmonic structure nor method of presentation of the reference tone has a significant effect upon tuning accuracy. The hypothesis is offered that unison tuning of musical instruments is dependent upon pitch-matching judgments rather than the discrimination of beats, as classically stated.
Pitch Shifts Accompanying Certain Auditory Threshold Shifts
Authors: Webster J. C. , Schubert E. D.
Published: September 2005

A method was developed for getting a continuous and running record of pitch matches between the two ears, using (1) the sychronized frequency- and paper-drive features of a “Bekesy” type audiometer and (2) the subject's adjustment of the frequency knob of a second oscillator to drive the recording pen. A one-second tone from the motor-driven (standard) oscillator (controlling the paper drive) is presented to one ear and a two-second tone from the subject's (variable) oscillator (controlling the pen writing mechanism) is presented alternately to the other ear. The subject, who controls the frequency of the variable tone, is instructed to keep the two alternating tones matched in pitch.

Ten music students made these pitch matches (90 matches per octave) from 150 to 9600 cps. In the ear in which the standard tone was heard various types and amounts of hearing loss were simulated by masking noises. The pitch tended to shift away from a region of hearing loss to a region of no, or less hearing loss. Downward shifts were observed but were never as marked as the upward shifts.
Tartini Versus Helmholtz Judged by Modern Sensory Observation
Authors: Meyer Max F.
Published: September 2005

Concerning the frequency location and the origin of the Tartini pitches the dogmatic assertions found in the textbooks of psychophysiological acoustics are the unhappy evolution of the hopeful guess ventured by Helmholtz that these secondary pitches and the physical combination tones produced by an air pressure tank could be regarded as analogous. In fact, they are incompatible.
Exploration of Cochlear Potentials in Guinea Pig with a Microelectrode
Authors: Tasaki I. , Davis H. , Eldredge D. H.
Published: September 2005

The ac (“microphonic”) cochlear potential and the positive dc “endolymphatic” potential have been recorded simultaneously as the exploring electrode was introduced into scala media or as other parameters were varied. Negative intracellular de potentials were demonstrated in the cells of the organ of Corti. The zone of positive endolymphatic potential is bounded by the reticular lamina, not by the basilar membrane. The cochlear microphonic reverses phase as the exploring electrode penetrates the reticular lamina. A dc polarizing current with the positive pole in scala media (and negative in scala tympani) increases the cochlear microphonic just as it does when the positive pole is located in the scala vestibuli. These facts indicate that the source of the ac (microphonic) potential seems clearly to be at the hair-bearing end of the hair cells and that the source of the dc endolymphatic potential is probably here also, while Reissner's membrane is not the source of either the ac or the dc potential. No steady dc current flow outside scala media was found such as would be expected if stria vascularis were the dc source and if the hair cells modulated a dc current flow through them. The dc endolymphatic potential may be increased by as much as 10 percent if and while the basilar membrane is displaced toward scala vestibuli and may be decreased to 50 percent or less when and while it is displaced toward scala tympani. Isotonic solutions rich in potassium depressed the ac potential and nerve responses when introduced into scala tympani but not when in scala vestibuli only. The. dc potential, however, was not altered by high potassium concentration in scala tympani.
On Sound Absorption by Cylindrical Diffusers
Authors: Parolini Gino
Published: September 2005

Measurements were made on the acoustic absorption of plywood cylindrical diffusers coated with porous materials, such as glass wool. High absorption was obtained even in the low frequency range, owing to the resonance of the cylindrical plywood frame, and to sound scattering. The experimental values have been found in good agreement with those computed according to Cook and Chrzanowsky's theory.
Propagation of Sound over Single Absorptive Strips in Ducts
Authors: Young James E.
Published: September 2005

The behavior of single absorptive strips imbedded in one wall of a hard duct is discussed by several approximate methods. The approximations are introduced in the order of increasing complexity. As a result an orderly scheme is obtained by means of which one can predict relevant physical quantities, such as attenuation, reflection coefficient, etc., with an accuracy suitable for practical utilization.

It is assumed throughout that the strips, extending over the width of one wall but of specified length, can be described by their normal impedance ratios. The excitation of the strip-duct structure is that due to a plane wave.

Measurements taken for a range of strip-wavelength ratios such that 0.56⩽kl⩽22.4 indicate that the lumped-parameter approximation is generally inadequate.

A variational principle is derived which together with suitable trial functions yields attenuations agreeing with measurements to within a few percent over the entire range of kl values.

Some attention is given to those limiting strip configurations for which other authors have obtained exact solutions. Comparisons are made between these and the present results.
Metallurgical Effects of Ultrasonic Waves
Authors: Hiedemann Egon A.
Published: September 2005

This survey on the metallurgical effects of ultrasonic waves, including scientific and technological literature, deals with the following: A. The techniques for the treatment of melts by mechanical vibrations. 1. Mechanical vibrators. 2. Electromechanical transducers. 3. Ponderomotive effects of induced electrical currents. B. Metallurgical effects observed after ultrasonic treatment. 1. Reduction in grain size. 2. Degassing of melts. 3. Dispersion of other substances in melts. 4. Acceleration of rate processes. 5. Other metallurgical and related effects.
Ultrasonic Cavitation Thresholds in Water
Authors: Connolly W. , Fox F. E.
Published: September 2005

The temperature dependence of the minimum sound pressure needed to produce cavitation in gassy water has been measured over a range of 0 to 30°C. Both plane progressive and focused waves of frequency one megacycle per second were used. The cavitation pressure threshold Pc is not a linear function of temperature, and increases by a factor of 2.5 between 30 and 0°C. About 50 percent higher sound-pressure amplitude is needed to initiate cavitation than to maintain it. The relation of Pc to the reciprocal temperature, to viscosity, and to the degree of undersaturation is discussed.
Measurement of Dispersion of Velocity of Sound in Liquids
Authors: Carstensen Edwin L.
Published: September 2005

A technique for the direct measurement of the difference between the velocity of sound in two liquids is described. By choosing for a reference a dispersionless liquid, such as water, the technique becomes a sensitive method for measurement of the change of velocity with frequency in the test liquid. In practice the method is sufficiently sensitive so that changes in the velocity smaller than one part in 104 can be detected. Illustrative measurements are presented for an NaCl solution, sperm oil, and evaporated milk.
Acoustical Streaming in the Vicinity of a Cylinder
Authors: Raney W. P. , Corelli J. C. , Westervelt P. J.
Published: September 2005

Apparently contradictory reports in the literature concerning the acoustic streaming around a right-circular cylinder immersed in a viscous, incompressible fluid can be reconciled by reference to a universal curve giving (δDC/a) as a function of (a/δAC), where δDC is the DC boundary-layer thickness, δAC is the AC boundary-layer thickness, and a is the radius of the cylinder. The existence of such a curve has been verified experimentally for the case of a right-circular cylinder vibrating to and fro in solutions of water and glycerin with kinematic viscosities ranging up to 50 times that of water, over an octave of frequencies. This experimental work also confirms theoretical predictions that for small oscillation amplitudes the streaming patterns will be the same whether the cylinder oscillates in a quiescent fluid or is fixed in an oscillating fluid. An approximate equation for the form of the universal curve has been obtained theoretically for the case of a thin AC boundary layer, when the oscillation amplitude is small enough to insure the validity of a first-order perturbation solution. Preliminary results of experimental work at higher amplitudes are reported, and the effect of the compressibility of the fluid on the streaming is discussed.
Acoustical Studies of the Tractrix Horn. II
Authors: Jensen A. O. , Lambert R. F.
Published: September 2005

Experimental investigations have been carried out on the tractrix horn structure to determine its “free-field” radiation characteristics. Axial, off-axis, and polar response characteristics, as well as throat impedance data on a single cell horn, are presented for both small and large baffle mounting. Pertinent data on a two cell structure are also presented. These data show the tractrix performance to be comparable with that of the well-known exponential horn. A multicellular structure, while showing definite improvement in uniformity of angular distribution at high frequencies, exhibits undesirable band rejection characteristics within the useful frequency range of the horn.
Maximum Directivity Index of a Linear Point Array
Authors: Pritchard R. L.
Published: September 2005

The maximum directivity index of a symmetrical, linear point array has been calculated as a function of the number and spacing of the elements in the array. The excitation required to produce a maximum directivity index is not uniform, except for integral-half-wavelength element spacings, and in general the minor lobes of the directional response patterns produced are not of equal, nor of small, amplitude. For element spacings exceeding a half-wavelength, a conventional type of pattern and of excitation is found to produce the maximum directivity index. On the other hand, as the element spacing is reduced below a half-wavelength, the directivity patterns corresponding to the maximum directivity index become super-directive, and the directivity index may be improved relative to the value obtainable with uniform excitation. However, this improvement is obtained only at the expense of requiring large, reversed-phase excitation. Numerical results are presented for 3-, 5-, and 7-element arrays.
Experimental Investigation of Wedge Horns Used with Line Hydrophones
Authors: McKinney C. M. , Anderson C. D.
Published: September 2005

A study has been made of wedge-shaped horns used in conjunction with line sources. The horns are constructed from aluminum plates covered with cellular rubber. Measurements were made over the frequency range of 60 kc to 150 kc using horn lengths from 3 inches to 15 inches and horn angles up to 90 degrees. Results are given graphically in the form of directivity patterns as well as relative gain in sensitivity and beam widths as a function of the several parameters. At 80 kc beam widths as low as 10 degrees are obtained with at least 40 db suppression of the secondary lobes. The horns are easily fabricated and the beam width and sensitivity of the transducers are easily controlled by varying the horn angle.
Cumulative Effects of Repeated Bursts of White Noise on Threshold for 4000-cps Tone Pips
Authors: Lightfoot Charles , Jerger James F.
Published: September 2005

Cumulative effects of a two-second burst of thermal noise on the threshold shift for 35-millisecond tone pips were examined by tracing the threshold shift over the course of 100 successive noise bursts. When bursts were presented at a rate of 6 per minute, a systematic increase in the threshold shift for the 35-millisecond tone pip was observed over the 100 burst series. Changing the burst-pip interval from 90 to 445 to 1000 milliseconds had little effect on the degree of this accumulation, but changing the SPL of the burst had a marked effect. At a burst level of 110 db (SPL re 0.0002 microbar) the mean threshold shift increased by about 6 db between the 15th and the 100th burst. Decreasing the burst level to 100 db reduced the mean accumulation to about 4 db, and at a burst level of 90 db to about 1 db. Changing the burst presentation rate from 6 per minute to 3 per minute reduced, but did not eliminate, the cumulative effect. The degree of this cumulative phenomenon showed wide individual differences among subjects.

It is concluded that, unless proper allowances are made, the repetitive stimulation required by burst-pip audiometry may be a source of serious error. On the other hand, the reaction of an ear to repeated stimuli may prove to be a useful index of the ear's susceptibility to irreversible acoustic trauma.
Masking of Speech by Repeated Bursts of Noise
Authors: Pollack Irwin
Published: September 2005

The masking of speech by a periodically interrupted white noise was examined over a wide range of noise levels, rates of interruption, and noise-time fractions. To a first approximation, the masking produced by an interrupted noise is a constant fraction of that produced by a continuous uninterrupted noise. The masking produced by an interrupted noise is primarily a function of the interval between successive noise bursts and is relatively independent of the noise-time fraction and the rate of interruption of the noise, except insofar as these determine the interval between noise bursts. The effect of interrupted noise on the loudness of speech was also examined.
Pitch Discrimination, Mels, and Kock's Contentio
Authors: Stevens S. S.
Published: September 2005

Recent data on pitch discrimination are shown to agree reasonably well with the values that would be predicted on the assumption that jnd's for pitch are subjectively equal when measured in mels. The facts relating to diplacusis and the estimation of musical intervals suggest that the difference limen may be expected to vary irregularly with frequency. A further argument is made that Kock's theoretical explanation of pitch discrimination is invalid.
Ultrasonic Absorption in Acetate Solutions
Authors: Barrett R. E. , Beyer R. T. , McNamara F. L.
Published: September 2005

The amplitude absorption coefficient α for continuous ultrasonic waves in aqueous solutions of copper acetate, sodium acetate, and potassium acetate has been measured over a range of frequency from 7 to 45 mc, at temperatures between 5° and 50°C, and at concentrations up to 0.5 M. The experimental values for copper acetate solutions confirm the existence of a relaxation frequency at about 18 mc (at the higher concentrations). The results for sodium and potassium acetate solutions show an absorption coefficient below that of pure water at the higher frequencies. They also indicate the existence of relaxation frequencies below 10 mc.
Theoretical Investigation on the Diffraction of Light by Superposed Ultrasonic Waves
Authors: Satyanarayana Murty J.
Published: September 2005

An analytical treatment for the calculation of intensities of diffraction orders in a general case of superposed sound waves of frequencies in the ratio 1 :n and having any phase difference Δ is given proceeding from Raman and Nath's simplified theory for normal incidence. Because of the integral harmonic relationship between the frequencies of the sound waves superposed, a particular order may contain a number of combination lines in addition to the orders due to the individual sound waves. As such, Fues theory, which gives a single expression for the intensity of a combination line, cannot be applied to this case.

Expressions are obtained for the intensities of the diffraction orders in the two specific cases of even and odd values of n. In the case diffraction by two sound waves of frequencies in the ratio 1:2k+1 expressions for the intensities of the orders suggest symmetry in diffraction for all values of Δ. But, when the superposed frequencies are in the ratio 1:2k, the expressions suggest asymmetry in diffraction for all values of λΔ, except π/2. When Δ = π/2, the diffraction is, however, symmetric.

Using the expressions, the intensities of the diffraction orders obtained by two sound waves of frequencies in the ratio 1:3 superposed in three different phases 0, π/2, and π are calculated for the values of v1 = 1 and v3 = 1, 2, and 3.
Frequency Dependence of Ultrasonic Cavitation
Authors: Gaertner Wolfgang
Published: September 2005

On the basis of a simplified model an explanation for the high-frequency limit of ultrasonic cavitation is suggested and compared with published experimental data.
Gas Bubbles with Organic Skin as Cavitation Nuclei
Authors: Fox Francis E. , Herzfeld Karl F.
Published: September 2005

The hypothesis discussed that the cavitation nuclei consist in gas bubbles. Due to surface tension, small bubbles would dissolve in a very short time. If the bubbles are larger than 5×10−3 cm, or if the liquid is supersaturated, they may last longer or even be stable, but then no cavitation threshold exists.

The hypothesis expressed that the nuclei are very small bubbles, stabilized by an organic skin, which mechanically prevents loss of gas by diffusion. The cavitation occurs when the skin breaks and the threshold is determined by the breaking strength of the film and the size of the bubble.
Paradoxical Direction of Wave Travel along the Cochlear Partition
Authors: v. Békésy G.
Published: September 2005

The cochlear partition of the ear exhibits a strange phenomenon: waves produced by continuous sinusoidal stimulation may travel toward the vibrating source. A mechanical model was constructed which showed the same vibration pattern as the cochlear partition of the ear and the same paradoxical traveling direction. By stimulating various sections of the model it was possible to show how the traveling waves are formed and why their direction of travel is independent of the location of the driving source. This independence makes it clear why an over-all vibration of the bony walls of the capsule during hearing by bone conduction produces the same sensation as the transmission of the vibrations through the stapes.
Factors Determining the Sound Attenuation Produced by Earphone Sockets
Authors: Zwislocki Jozef
Published: September 2005

The factors that determine the sound attenuation provided by earphone sockets are analyzed on the basis of experimental evidence, and an attempt is made to determine the practical limit of sound attenuation attained by earphone sockets, when comfort and sound transmission from the earphone to the ear are taken into consideration. For frequencies below 700 cps the attenuation is limited by the mass of the system and the impedance of the flesh under the earphone cushion. For frequencies above 700 cps bone conduction is the determining factor.
Development of a Semiplastic Earphone Socket
Authors: Zwislocki I.
Published: September 2005

The semiplastic earphone socket is characterized by high internal viscosity and low elasticity. It can be deformed easily, but in the absence of external forces comes back to its original shape. The high viscosity has a strong sound attenuating effect. The paper describes the developmental steps leading to the design of a circumaural semiplastic socket and the performance of the socket. Its most outstanding features are high noise attenuation and comfort.
Transmission of the Vocal Cavities
Authors: van den Berg Jw.
Published: September 2005

The transmission of the vocal cavities has been determined for eleven cardinal vowels of the I.P.A., using a hemilaryngectomized subject. A special throat loudspeaker with pick-up was constructed and was fitted in the throat of the subject, leaving a gap beneath it for normal breathing.
Imitation of Dutch Vowels and Words by a Hemilaryngectomized Subject Using a Throat Loudspeaker as a Pseudolarynx
Authors: van den Berg Jw.
Published: September 2005

Using a specially constructed throat loudspeaker, Dutch vowels and words were imitated by a hemilaryngectomized subject. A known mixture of harmonics was delivered to the larynx, and the subject shaped his mouth in agreement with the desired sound. Conclusions are drawn about the most effective harmonic spectrum at the larynx, and about the so-called vowel pattern in the larynx.
Some Effects of the Distribution of Added Mass to Vibrating Beams
Authors: Cohen Hirsh , Handelman George
Published: September 2005

The effect produced on the eigenfrequencies of vibrating beams the addition of mass in such a manner that a portion of the beam is rigidified is investigated.
Graphical Representation of the Spherical Propagation of Explosive Pulses in Elastic Media
Authors: Goldsmith Werner , Allen William A.
Published: September 2005

The problem of spherically symmetric wave propagation in homogeneous, isotropic elastic media of infinite extent has been examined frequently in recent years, and a number of analytical solutions have been reported in the literature for various initial conditions. Some interest has also been exhibited in the application of these relations to the transient phenomena occurring in metals when subjected to contact explosions. Under these conditions, an actual wave system can be approximated by postulating the existence of a spherical cavity in the interior of the medium and applying as the initial condition a pulse of exponentially decaying character. While no difficulty is encountered here in an analytic expression of the displacements, velocities and stresses occurring at each point of the medium as a function of location and time, it has been found highly desirable to represent these terms in pictorial form to permit a rapid evaluation of the nature of the disturbances in the region of interest. Consequently, numerical calculations have been performed on an IBM machine and the resultant data have been employed in a space-time representation of these parameters.
Steady State Response of the Sperry Rate Gyrotron or Vibratory Gyroscope
Authors: Morrow Charles T.
Published: September 2005

A vibratory gyroscope or Gyrotron has been under development at the Sperry Gyroscope Company for the Bureau of Aeronautics as an instrument for measuring rate of turn. The instrument utilizes a tuning fork which undergoes a torsional vibration due to Coriolis forces when a rate of turn is applied. Thus, a familiar acoustical device is applied to the problem of control of aircraft. The absence of bearings gives it virtues of low electrical noise level, ruggedness, and long life. This paper presents a simplified analysis of the response of the instrument to steady rates of turn, with special emphasis on linearity considerations.
Measurements of the Absorption of Ultrasonic Waves in Liquids by the Method of Isochromates
Authors: Kannuna M. M.
Published: September 2005

The method of isochromates was used to measure the absorption of ultrasonic waves in m-xylene, toluene, carbon tetrachloride, and benzene. The results are summarized in a table.
Response of the Sperry Rate Gyrotron to Varying Rates of Turn
Authors: Morrow Charles T.
Published: September 2005

The response of a tuning fork rate Gyrotron or vibratory gyroscope to steady rates of turn was discussed in a previous paper [J. Acoust. Soc. Am. 26, 56(1955)]. The treatment is now extended to yield the amplitude and phase response of the instrument to impressed oscillation about the sensitive axis. The results can be used in calculating the stability of a servo loop incorporating Gyrotron as an element.
Noise of Centrifugal Fans
Authors: Beranek Leo L. , Kamperman George W. , Allen Clayton H.
Published: September 2005

Extensions of earlier studies [J. Acoust. Soc. Am. 26, No. 2(1953)] on ventilation system noise are reported. It is shown here that in properly engineered ventilation systems the over-all sound power level in decibels re 1013a watt is related to the horsepower rating of the fan motor by the formula: PWL = 100+10 1og10hp. The octave frequency band spectrum slopes off with increasing frequency at the rate of 5 decibels per octave. The level in the first band is one decibel below the over-all level. Measured data on fourteen fans in actual installations yield a spread of about ±4 db around these relations.
An Analog Electronic Correlator for Acoustic Measurements
Authors: Goff Kenneth W.
Published: September 2005

A study has been made of the applicability of correlation techniques to the field of acoustic measurements. The development of an analog electronic correlator for this study is reported here while the application of the correlation technique to some acoustic measurements is reported in a companion paper.

The analog correlator is divided into the following four main components and each one is discussed in detail: (1) variable time delay; (2) quarter-squaring multiplier; (3) continuous and stepping integrators; (4) system for scanning and plotting the crosscorrelation function on both linear and logarithmic scales.

The correlator operates over an input frequency range of 100 cps to 10 kcps, a range of relative time delay τ from −15 to 190 milliseconds and RC integration times of 0.5 to 16 seconds. A dynamic range in the crosscorrelation function of approximately 50 db is achieved with ±1 db accuracy.

Special attention has been given to the errors in the crosscorrelation function resulting from finite integration time and scanning of the correlation function. A significant increase in permissible scanning speed for a given signal-to-noise ratio has been shown to result from “matching” the equivalent integrator pass band to that of the spectrum common to the two signals applied to the correlator. Relations have been derived between scanning speed, signal-to-noise ratio, and input signal band width for integration performed by either a low-pass filter or a "matched" filter.
Fundamental Frequencies of Clamped Triangular Plates
Authors: Cox Hugh L. , Klein Bertram
Published: September 2005

Approximate solutions are given for the fundamental frequencies of flexural vibration of flat triangular plates with all edges clamped. The plate equation is written in skew coordinates and the method of collocation is used to obtain the approximate solutions. Results are presented in simple graphical form so that one may determine rapidly a desired fundamental frequency.
Studies on Acoustic Radiation Pressure. II. (Radiation Pressure on a Circular Disk)
Authors: Awatani Jobu
Published: September 2005

A general formula for the radiation pressure acting on a thin rigid circular disk is derived from the theory of the previous paper. Motion of the disk under action of the wave and diffraction of the wave due to the disk are taken into account. Constants which may be calculated by the use of the oblate spheroidal functions necessary in obtaining the radiation pressure are given in the table. Numerical calculation for disks of various weight with the ratio of the circumference of the disk to the wavelength of sound up to 3.5 is carried out.
Ultrasonic Dispersion in 1,1- and 1,2-Dichloroethane Vapors
Authors: Rao T. Seshagiri , Hubbard J. C.
Published: September 2005

The ultrasonic resonator interferometer has been used to measure the ultrasonic velocity at 30°C in 1,1-dichloroethane (ethylidene chloride, CH3CHCl2) and 1,2-dichloroethane (ethylene chloride,CH2Cl-CH2Cl) vapors as a function of frequency over pressure. The ranges f/p employed are 0.8 to 100 Mc sec−1 atmos−1 in the case of ethylidene chloride and 1.0 to 100 Mc sec−1 atmos−1 in the case of ethylene chloride. The velocities have been corrected for nonideality of the two vapors. Dispersion of ultrasonic velocity occurs in both the cases and this is ascribed to the slow rate of energy exchange between translational and vibrational states. There is evidence of double relaxation in the two cases, the principal f/p ratios at 30°C being 76.5 Mc sec−1 atmos−1 for the former and 102 Mc sec−1 atmos−1 for the latter.
The Apparent Reduction of Loudness: A Repeat Experiment
Authors: Stevens S. S. , Rogers M. S. , Herrnstein R. J.
Published: September 2005

The experiment of Laird, Taylor, and Wille (1932) showed that the reduction in the intensity of a sound required to produce half-loudness is of the order of 20 db. Since this result is out of line with most other studies in this field, an attempt was made to repeat the experiment with a similar piece of apparatus (2-A audiometer). The first attempt to copy the procedure of Laird, Taylor, and Wille gave results more like those usually obtained, namely, a required reduction for half-loudness of the order of 10 db. A second experiment, involving the use of comparison tones placed as much as 40 db below the standard, gave results more like those of Laird, Taylor, and Wille. The method they used appears to be overly sensitive to the range and order of presentation of the comparison stimuli.