bluuebunny/crossref_metadata_2025 huggingface dataset:
Forward Scattering of Sound in the Sea and Its Correlation with the Temperature Microstructure
Authors: Whitmarsh D. C. , Skudrzyk E. , Urick R. J.
Published: September 2005

Scattering measurements are compared with the predictions of the existing theories. The agreement is satisfactory. Measurements of the temperature microstructure, however, lead to unexpected results, showing that the patch sizes or scales of patch sizes are continuously distributed and that the temperature fluctuation increases continuously with range. There seems to be almost perfect agreement with the results of the theory of homogeneous turbulence and the temperature fluctuations in water. This would appear to invalidate the present theories, since a correlation function as defined in the usual sense does not exist. If, however, the correlation function is replaced by a new function in connection with a suitably defined temperature distribution, practically all the results of the current theory can be shown to remain valid, and it becomes possible to explain other items as, for instance, the independence of acoustical scattering with depth, and acoustical predominance of certain patch sizes, which hitherto had not been understood. The acoustically effective patches turn out to be a function of the frequency and range rather than of the particular conditions of the sea.
Moiré Fringe Analogs in Underwater Acoustics
Authors: Weston D. E.
Published: September 2005

Recently, the writer described a moiré fringe analog for underwater sound modes. Now, attention is given to the work of Pohl and Shubnikov with moiré patterns from circular grids which are of possible use in underwater array design and underwater sound propagation investigations.
Maximum Power Criterion for the Vibrating Free Edge Disk
Authors: House Raymond N.
Published: September 2005

A criterion for the maximum radiated power delivered by a high-efficiency piezoelectrically driven free disk, vibrating in the first symmetrical mode, has been developed. The maximum power emitted from such a transducer is necessarily limited by maximum stresses and strains to which the disk is subjected when undergoing transverse vibrations. A complete solution of the stress and strain distribution is given for this mode of vibration. Maximum values for these stresses and strains occur at the center of the vibrating plate. Assignment of a safe stress level, dependent on material, which the center of the vibrating plate must not exceed, then yields a unique value of maximum center velocity at which disk fracture occurs. The maximum power criterion is then established by the maximum safe center velocity, which is shown to be independent of plate geometry, and the radiation resistance of the disk in its operating medium. Experiment shows, as anticipated, that fracture occurs at the geometric center of the vibrating plate, with power values consistent with the theory.
Acoustic Radiation Pressure Bearing
Authors: Seegall Manfred I.
Published: September 2005

This paper gives a brief investigation of the concept of the acoustic bearing, the force of which is based on radiation pressure of a resonating sound wave. Of the principal configurations possible, a cylindrical geometry with plates on the ends of the cylinder was considered to be the most suitable. Output ratios of the order of 2640 d/w are shown to be obtainable. Experimentation reached a resonant amplification of 80; ways are shown by which amplifications of around 100 can be achieved. Beyond that internal absorption losses and cavitation present formidable obstacles which, at this point, cannot be overcome.
Analyses of Soprano Voices
Authors: Bjørklund Alf
Published: September 2005

An analysis of the voices of sopranos, ranging from singers without any education to artists of world fame, shows a distinct correlation between level of training and vibrato of the voice. Furthermore, analysis of the voices of singers performing in rooms with short reverberation time shows that education is important for the ability to sing correct pitch in words of more than one syllable when the syllables have different pitches. In the analysis of 66 sustained notes, some irregularities were observed in the frequency variations of the overtones. A series of recordings was carried out to detect a plausible reason for these irregularities. The results of various methods of analysis confirm the author's assertion that the sustained note from a highly trained soprano may have parts where the complex wave representing the note is not composed of harmonics.
Comparison of the Take-Off Noise Characteristics of the Caravelle Jet Airliner and of Conventional Propeller-Driven Airliners
Authors: Miller Laymon N. , Beranek Leo L.
Published: September 2005

Based upon earlier published information concerning the factors that influence neighborhood response to noise exposure, it is assumed that there are three principal characteristics of noise which must be considered in comparing community response to jet take-offs with that due to propeller aircraft take-offs. These three noise factors are: (1) relative noise levels; (2) duration of noise; and (3) frequency distribution of noise. This paper is devoted to a comparison of the noise produced by the French jet aircraft, the Caravelle, with that produced by conventional propeller-driven airliners in terms of these three factors. Noise level measurements were made under the take-off path at various distances from the beginning of the take-off run-way. The conclusion is drawn that the comparative noise levels of the Caravelle, when considered in terms of probable response of listeners to the spectrum distribution of the noise, are approximately equal to those of large propeller aircraft for similar climb rates when heard out-of-doors. Second, the Caravelle noise levels, based on relative listener response, are somewhat lower than those of propeller aircraft when heard in-doors or when the Caravelle is permitted to take off under steep climb conditions. Third, the Caravelle noise persists for longer time intervals than does propeller aircraft noise by a factor of between 1.5 and 3.5, depending upon the distance from the runway.
On the Properties of Voiceless Fricative Consonants
Authors: Heinz John M. , Stevens Kenneth N.
Published: September 2005

According to an acoustical theory of speech production, the spectra of voiceless fricatives can be characterized by poles and zeros whose frequency locations are dependent on the vocal-tract configuration and on the location of the source of excitation within the vocal tract. The locations of the important poles and zeros in the spectra of fricatives can be determined by a matching process whereby comparison spectra synthesized by electric circuits are matched against the spectra under analysis. This method has been used to determine the frequencies and bandwidths of the important poles and zeros for several versions of /f/, /s/, and /∫/. Based on these findings, a simplified electrical model is developed for the synthesis of voiceless fricatives. The model consists of a noise-excited electric circuit characterized by a pole and a zero whose frequency locations can be varied. Stimuli generated by this model, both in isolation and in syllables, are presented to listeners for identification. The results of the listening tests are consistent with the data from the acoustic analyses and with the findings of other investigators.
Perturbations in Vocal Pitch
Authors: Lieberman Philip
Published: September 2005

An acoustic analysis of the rapid fluctuations that occur in the fundamental excitation rate, or “pitch,” of normal speech was conducted with a sample of six male speakers of American English, who each read a neutral test sentence in certain “emotional” modes. i.e., as a question, an objective statement, a fearful utterance, a happy utterance, etc. A statistical analysis of the durations of approximately 7000 pitch periods was performed with an IBM 709 computer. This analysis revealed that for all possible samples consisting of three consecutive periods, the duration did not remain constant, within ±0.1 msec, in 86% of the cases. The data also showed that the magnitude of the difference between the durations of adjacent periods was greater than 0.6 msec 20% of the time and greater than 1.0 msec 15% of the time. The magnitude of this difference increased with the duration of the periods until their duration reached 6 msec. The difference was independent of the period duration for periods longer than 6 msec. Somewhat greater differences between the durations of successive periods occurred in those samples associated with the onset and end of voicing and sudden spectral shifts. Smaller differences occurred with certain of the emotional modes that seemed to require greater conscious vocal control in their production.

The output of the glottis often seemed to be like that of an oscillator with considerable overshoot. In 38% of the cases it produced a sequence of alternately short and long duration periods. The durations of adjacent periods were not correlated. The durations of alternate long and alternate short periods, however, were highly correlated, suggesting a hysteresis effect in which the duration of each period is determined with respect to the preceding period in a quasi random manner within a 2-msec range.
Oppositely Directed Plane Finite Waves
Authors: Fay R. D.
Published: September 2005

The analysis is carried out in terms of particle velocities expressed as Mach numbers. In general, the pertinent quantities are expressed in relation to the infinitesimal values by a power series of these Mach numbers ha which two powers are retained. To this order of approximation, the particle velocity is the vector sum of the particle velocities of the isolated component waves and the speed of propagation in each direction has an increment proportional to the vector difference of these particle velocities. The general behavior of the sound field may be predicted from these two relations.
Exact Transient Solution of Some Elementary Problems of Elastic Wave Propagation
Authors: Flinn Edward A.
Published: September 2005

Two elementary problems of guided elastic wave propagation—a point source of SH waves in a free solid plate, and an arbitrary distribution of torsional stress across a normal section of a solid free cylinder—are considered, and exact transient solutions derived.
Variational Treatment of Arbitrary Mass-Loaded Membranes
Authors: Kornhauser E. T. , Van Hulsteyn D. B.
Published: September 2005

A variational principle applicable to mass-loaded membranes of arbitrary shape is used to demonstrate the validity of several conclusions inferred in a previous paper from the rigorous results for the center-loaded circular membrane.
Input Impedance of a Beam Coupled to a Plate
Authors: Lamb George L.
Published: September 2005

The flexural vibration of an infinite elastic beam which is excited by a localized harmonic driving force and attached over its entire length to a thin elastic plate of infinite extent is investigated theoretically. The results are expressed in terms of two parameters, kbL and r. The parameter kbL describes the frequency dependence and degree of beam-plate coupling; and the parameter r is the ratio of flexural wave velocity on the plate to that on the beam. For r<1, strong radiation into the plate is possible, while for r>1, plate excitation is localized near the beam. In geometries of practical interest, the strong radiation case prevails. Small deviations in the input admittance of the beam from that of a free beam are initially obtained by employing a perturbation procedure which is valid in the limit kbL≫1, the relevant range for geometries of practical concern. In addition, a variational principle for the admittance is constructed and shown to yield the results of the first-order perturbation solution when the displacement of a similarly excited free beam is used as a trial function. At very high frequencies the input admittance is found to approach that of a free beam, while at lower frequencies it is found that the plate adds an additional stiffness susceptance to the input admittance. For a typical beam-plate geometry it is found that the beam is affected by the plate for all forcing frequencies below about 5000 cps and may be estimated by the results of the present calculation down to a few hundred cps.
Transmission of Plate Flexural Waves through Reinforcing Beams; Dynamic Stress Concentrations
Authors: Ungar Eric E.
Published: September 2005

An infinite plate to which a narrow infinitely long beam is attached rigidly and continuously may be considered as an idealization of some typical flight vehicle structures. Reflection, transmission, and near-field effects, associated with a straight-crested flexural wave impinging on one side of the beam, are presented as functions of the properties of the plate and beam and interpreted in terms of trace matching of the flexural waves in the plate with flexural and torsional waves in the beam. The concepts of dynamic stress and strain concentration factors are discussed, and upper bounds on these factors are given. Some implications pertaining to the design of beam reinforced panel structures with favorable fatigue properties are pointed out.
Peak Criterion in Random vs Sine Vibration Testing
Authors: Spence H. R. , Luhrs H. N.
Published: September 2005

Sinusoidal vibration has practical value as a substitute for random vibration in equipment qualification testing. How and when to employ a sinusoidal substitution is discussed in this paper. In particular, a damage criterion is discussed, which relates the number of sinusoidal peaks occurring while passing through a resonance to the number of random peaks exceeding a specified amplitude value.

Formulas are given for the sine-random response relationship, with formulas and a diagram for the random test duration to be used with the amplitude relationship.
Response of Two-Degree-of-Freedom Systems to White Noise Base Excitation
Authors: Curtis Allen J. , Boykin Thomas R.
Published: September 2005

The response of a coupled two-degree-of-freedom system to white noise excitation is obtained analytically for a wide variation of the dimensionless parameters of the system. The interrelations of these parameters on the response are illustrated and shown to be very significant when the uncoupled natural frequencies of the system are of the same order. The limitations of approximation methods based on single-degree-of-freedom system or uncoupled two-degree-of-freedom system models are indicated. The applicability of the study to dynamic vibration absorber principles is evident. The responses are compared to previously published results.
Experimental Study of the Scattering of Acoustic Energy from Solid Metal Spheres in Water
Authors: Hampton L. D. , McKinney C. M.
Published: September 2005

An experimental study of the scattering of acoustic energy from solid metal spheres in water has been carried out in the frequency range 50–150 kc and with a range of sphere sizes from 1 to 7 in. in diam, giving values of ka (acoustic radius) from 4.1 to 57. Data are presented which show the scattered pulse formation for pulses which are short compared to the sphere and for pulses which are long compared to the sphere as a function of frequency, of scattering angle, and of sphere composition. The study shows that the spheres cannot be treated as rigid bodies since an appreciable amount of energy penetrates the surface and results in a complicated echo structure for the scattered signal. The back-scattered target strength of spheres for short pulses (and considering only the surface-reflected pulse) is essentially constant with frequency for large ka, and is slightly less than the theoretical value for rigid spheres. For pulses which are long compared to the transit time across the sphere, the target strength fluctuates as much as 30 db for small changes in frequency. For short pulses the angular distribution of the scattered energy is fairly uniform over the back 180°, but this is not true for long pulses.
Effect of an Internal Wave on Sound in the Ocean
Authors: Lee Owen S.
Published: September 2005

A sound intensity field that is influenced by refraction of high frequency sound in a high-frequency internal wave is compared with the intensity field in the same medium with no internal wave on the thermocline. Ideal ocean mediums composed of three distinct layers are assumed for both cases. The surface layers have no sound velocity gradient, and the other two layers in both mediums are characterized by linear sound velocity gradients. Properties of the internal waves are similar to those observed off the coast at San Diego, California, in the summer months. The results show that narrow zones of high intensity and broad zones of low intensity alternately occur over a range as predicted by an earlier theory. In the first case (no internal wave in the medium 1, contrasts in the intensity of about 5 db occur over distances of one internal wavelength or less. In the second case (an internal wave in the medium), intensity contrasts of as much as 22 db occur over the same distance.
Some Factors Affecting the Estimation of Loudness
Authors: Hellman R. P. , Zwislocki J.
Published: September 2005

In order to obtain a reasonably unbiased loudness function near the threshold of audibility by the method of magnitude estimation, several possible causes of bias were investigated. The investigation included a comparison between sound pressure level and sensation level as independent variables and a parametric variation of the reference SL and of the reference number. It is established that for certain pairs of reference SL's and reference numbers a reasonably unbiased loudness function can be determined down to a SL of 4 db.
Acoustic Irritation Threshold of Ringbilled Gulls
Authors: Thiessen G. J. , Shaw E. A. G.
Published: September 2005

When exposed to high-intensity sound, ringbilled gulls do not, to any extent, show the head-shaking reaction that was previously observed for ducks. They do, however, show a great tendency to cringe or crouch and are also subject to a temporary change in the rate of heart beat. These reactions are used to define and measure an acoustic “irritation threshold” at different frequencies between 100 and 3000 cps. The threshold determined with reference to the cringing reaction is remarkably reproducible over a period of weeks (having an average minimum value of about 85 db at 400 to 500 cps) but rises considerably during the first eleven months of the bird's life.
Descent of the Median: Reply to Gerstman and Bricker
Authors: Rubenstein Herbert , Pollack Irwin
Published: September 2005

In the presentation of an unknown message set in noise, the the median word frequency of the incorrect responses is shown to inversely related to the speech-to-noise ratio. The hypothesis that this relationship is an epiphenomenon of increasing knowledge of the message set is rejected.
On the Fermi Surface Shapes of the Noble Metals by Ultrasonic
Authors: Morse R. W. , Myers A. , Walker C. T.
Published: September 2005

Some revised conclusions are given concerning the Fermi surface shades of the noble metals as determined ultrasonically. The main new conclusions are: (a) The relative amount of zone boundary touching in copper and gold is nearly the same. (b) There is evidence that the main bodies of the surfaces are considerably more distorted than previously believed, being bulged outward along [100] and possibly being concave in the [110] direction.
Speech Communications at High Noise Levels: The Roles of a Noise-Operated Automatic Gain Control System and Hearing Protection
Authors: Pollack Irwin
Published: September 2005

Two aids for hearing conservation, a noise-operated automatic gain control system and an insert ear protection, were evaluated in terms of their effect upon speech intelligibility. At high noise levels, these aids not only do not interfere with the speech intelligibility, they may substantially improve speech intelligibility while affording hearing protection.
Effect of Noise and Filtering on Speech Intelligibility at High Levels
Authors: Pollack Irwin , Pickett J. M.
Published: September 2005

The effects of high sound levels on wide-band speech in noise roughly parallel the effects of high levels on filtered speech. The Articulation Index (AI) concept encompasses both findings if it is assumed that the effect of high sound levels is to produce an effective change in AI.
Optical Calibration of Vibration Pickups at Small Amplitudes
Authors: Schmidt V. A. , Edelman S. , Smith E. R. , Jones E.
Published: September 2005

A photometric device for accurately measuring the amplitudes of sinusoidal vibrations is described. The device is designed for calibrating vibration pickups. The apparatus employs a Fizeau-type interferometer with a photomultiplier observing the fringe pattern. The method is applied to the measurement of vibrations throughout the audio and near ultrasonic frequency range with amplitudes ranging from 72 to 4400 A. Extension to amplitudes as low as 5 A can be made with some modification to the apparatus.
Background Information on the Activities of Committee Z24-W-18, Sound Level Meters
Authors: Hardy Howard C.
Published: September 2005

This symposium on sound level meters is essentially a report of Committee Z24-W-18 of the American Standards Association, which for three years has been evolving a new standard for sound level meters. This new standard is more than a revision of the current one (Z24.3-1944), since early in the deliberations of the committee it was decided that the standard warranted a completely new draft.

All persons participating in the symposium are either members of Committee Z24-W-18 or have been closely associated with the committee activity. In addition to the participants, other committee members have done yeoman work in the preparation of the draft through its numerous revisions. These other members are Mr. George Bonvallet, Dr. Arnold Peterson, Dr. Paul Veneklasen, Dr. Richard Wells, and the late Dr. Paul Geiger.
Acoustic Treatment of the Cleveland Public Auditorium
Authors: Hunter Joseph L. , Mull Harold R.
Published: September 2005

The main arena of the Cleveland Public Auditorium is one of the largest listening chambers in the world. Built in the early 1920's, it has, since its opening, been the scene of important public functions, including presidential conventions. Criticism of its acoustic qualities had existed from its opening, but had increased rapidly since 1950, and in 1955 the city administration called for a thorough study of its acoustic qualities and recommendations for improvement. This paper consists of a description of the initial acoustic study, including articulation testing and reverberation time measurements, the problems involved in the acoustic treatment, the actual application of the treatment, and opinions of users since completion.
Memory for Waveform and Time Uncertainty in Auditory Detection
Authors: Egan James P. , Schulman Arthur I. , Greenberg Gordon Z.
Published: September 2005

An experiment was conducted to determine how well listeners could judge whether or not a signal was presented in a noisy observation interval which had already occurred. The cardinal feature of the experiment is that the observation interval is not marked off for the listeners until some fixed time after its occurrence. The listening situation is described as follows. With a probability of 0.5, the signal (1000 cps, 0.25 sec) is presented at a randomly selected instant. A fixed time thereafter, the listener is informed (by a flash of light) of the real time at which the sinusoid may have occurred, and he responds with a rating of confidence. As compared with the typical fixed-interval experiment in auditory detection, two sources of uncertainty are emphasized in this situation: (1) The listener has a faulty memory of his transformation of the input waveform, and (2) he has a faulty estimation of the time of onset of the signal. From the results of previous experiments on the role of time uncertainty in detection, it appears that a fair portion of the decrement in performance results from poor memory for the input waveform.
Exploratory Studies on Temporary Threshold Shift from Impulses
Authors: Ward W. Dixon , Selters Weldon , Glorig Aram
Published: September 2005

Some exploratory studies of temporary threshold shifts (TTS) induced by acoustic pulses are described. Attempts to determine the effect of pulse rate on TTS were only partially successful because at rates of 1 click/sec or more, residual activity of the protective reflex produced by one click reduced the effective intensity of the next click. The protection induced by this reflex was next examined by using, TTS from clicks as the dependent variable; a tone of 1000 cps at 103 db SPL, presented to the contralateral ear 105 msec before the click, reduced its effective intensity by about 10 db. The TTS at 4 kc was shown to increase linearly with exposure time; that is, the TTS from pulses is proportional to the number of pulses presented. The average TTS produced by pulses has a broad maximum at 4 kc, but this maximum may vary from 2 to 10 kc for different observers. Striking individual differences were observed throughout the experiments. Certain aspects of the distinction of pitch that is often correlated with large values of TTS are described.
Analysis of a Multiple Receiver Correlation System
Authors: Jacobson Melvin J.
Published: September 2005

A theoretical study is made of an acoustic receiving system which contains a single correlator whose inputs are obtained from arrays of omni-directional receivers. Mathematical expressions are developed for the mean system output when the input arises from a distant localized signal source. In addition, two major advantages of multiple receiver correlation as compared to two receiver correlation are discussed in detail. These are improved directional patterns on narrow band signals and increased output signal-noise ratio resulting from the use of more than two receivers.
Active, Adjustable Audio Band-Pass Filter
Authors: Macdonald J. Ross
Published: September 2005

An active, adjustable band-pass filter having seventh-order Butterworth attenuation characteristics (42 db/octave slopes) is described. It has 34 separate high-pass cutoff frequencies between 16.2 cps mad 16 200 cps and 34 low-pass cutoffs between 20 cps and 20 000 cps. The filter weighs six pounds exclusive of power supply mad uses six miniature double triodes and no inductors. Its insertion gain is 4.5 db, its dynamic range exceeds 110 db, and it will supply more than 50 v rms output with low distortion. Second-order harmonic distortion is much reduced by running tube heaters at about 3.7 v, leading to greatly increased tube life. Intermodulation distortion at 10 v rms output is only 0.065%.
Effect of Membrane Strain on Fatigue Damage Rate. Asymptotic Calculation
Authors: Lyon Richard H.
Published: September 2005

The effect of membrane strain on thee fatigue damage rate of a bar with simply supported ends is calculated based on asymptotic expressions for the extremal moments of a hard-spring oscillator. The calculations are appropriate for a high degree of nonlinearity. Comparisons with numerical calculations are satisfactory.
Elastic Wave Dispersion in a Cylindrical Rod by a Wide-Band Short-Duration Pulse Technique
Authors: Oliver Jack
Published: September 2005

Dispersion of elastic waves in a cylindrical rod, determined experimentally by means of a wide-band short-duration pulse technique, compares well with theoretical curves of the classical theory. This method, compared to previous methods, extends to smaller values the range of the wavelength to diameter ratios which may be studied conveniently.

One antisymmetric and two symmetric modes were studied. In addition, waves of a resonant nature associated with the ends of the rod were identified.
Scattering of Sound by Sound
Authors: Westervelt Peter J.
Published: September 2005

Owing to the inherent nonlinearity of the equations of motion for a perfect fluid, two or more sound waves passing through a common region will, in general, interact with one another and give rise to scattered waves. In this paper, a source function is obtained for the lowest order scattering process which is quadratic in the primary field variables. This function is rewritten in a form that demonstrates that no scattered waves exist outside the region of interaction of two sound beams intersecting each other at right angles. Furthermore, it is demonstrated that no such scattered waves exist when the two beams intersect at the angle θ = −cos−1[12ρ0c0−2(d2pdρ2)ρ = ρ0], where ρ, c, and p stand for the density, sound velocity and pressure, respectively, and the subscript 0 means ambient values of these quantities. The interfering effect of pseudo-sound, induced by radiation pressure, is suggested as an explanation for the results of Ingard and Pridmore-Brown, who have reported recently what they believe to be scattered waves from the interaction region of two sound beams intersecting each other at right angles.
Sound Radiation from Prolate Spheroids
Authors: Chertock George
Published: September 2005

Spheroidal coordinates and wave functions are used to analyze the sound radiation from a prolate spheroid whose surface vibrates in an arbitrary pattern. Expressions are derived for the pressure distribution, velocity amplitude, radiation impedance, and directivity factor in each spheroidal radiation mode. Numerical results are derived for two special examples: (1) a rigid-body vibration of a thin spheroid, and (2) an “accordion-like” vibration of a thin spheroid.
On the Reflection of Sound at an Interface of Relative Motion
Authors: Miles John W.
Published: September 2005

The reflection of a plane wave of sound at an interface between two perfect fluids is considered. Previous analyses of Rudnick, Keller, and Franken and Ingard are found in error as a result of improper boundary conditions. It is found that, in addition to the possibility of total reflection in some range of angles of incidence at all finite, relative speeds, there exists the possibility of a reflection coefficient exceeding unity for sufficiently high, supersonic speeds; in particular, resonance may occur at one or more angles of incidence. The question of stability of the vortex sheet separating the two fluids also is discussed.
Concerning the Fundamental Component of Periodic Pulse Patterns and Modulated Vibrations Observed on the Cochlear Model with Nerve Supply
Authors: v. Békésy G.
Published: September 2005

Seebeck demonstrated that there are series of clicks for which Fourier analysis shows a very small fundamental component or none at all, in spite of the fact that a distinct tone complex close to the fundamental component can be heard. Similarly, in a modulated tone, the modulation frequency as such may be heard without being present in the Fourier analysis.

This paper shows that on the model of the cochlea the artificial basilar membrane vibrates at the place corresponding to the absent fundamental or the modulation frequency. The vibration seems to be a consequence of the complicated traveling-wave patterns and their interferences. This may be of interest for some hearing theories.
On the Vibration of a Circular Membrane with Added Mass
Authors: Cohen Hirsh , Handelman George
Published: September 2005

The characteristic frequencies of a circular membrane carrying a rigidly attached concentric circular mass of finite area and vibrating symmetrically are studied. The main problem is that of determining the ranges of the parameters for which the frequencies will always be above or always be below those of the unloaded case. One of the chief tools is the minimum principle appropriate to the problem. The first term in the asymptotic expansion of the higher frequencies is obtained.
Seismometer Sounds
Authors: Speeth Sheridan Dauster
Published: September 2005

By time-compressing the output of a seismometer, it is possible to present seismographic data in an auditory display. Preliminary data suggest that the seismic sounds due to natural earthquakes may be distinguishable from those due to underground explosions. Some functions are presented to indicate how probability of detection varies with amount of initial training and distance of the seismometer from the explosion source. Other applications of auditory displays in the analysis of seismological data are suggested.
Double Relaxation Effects
Authors: Beyer Robert T.
Published: September 2005

Detailed consideration is given to several situations in which two relaxation processes contribute to the absorption of ultrasound. A general but rather involved expression is given for αλ. From the particular cases examined, it appears that when the relaxation frequencies of the two processes are close together, a single experimental relaxational frequency will be observed, with (αλ)max somewhat higher than the value obtained by combining the two separate peaks. The observed relaxation frequency will be approximately equal to the lower of the two individual relaxation frequencies.
Time vs Intensity in the Localization of Tones
Authors: Whitworth Randolph H. , Jeffress Lloyd A.
Published: September 2005

Subjects were asked to match the lateral position of one tone, the “signal,” by means of another, the “pointer.” The two tones were presented alternately. The experimenter selected a combination of interaural time and intensity differences for the signal, and the subject adjusted the interaural time difference for the pointer until it seemed to him to be in the same lateral position as the signal. Subjects having normal hearing perceived the signal in two places, one strongly affected by the difference of level at the two ears, the other almost wholly dependent upon the difference of time.
Overstimulation, Fatigue, and Onset of Overload in the Normal Human Ear
Authors: Lawrence Merle , Yantis Phillip A.
Published: September 2005

Studies on the effect of overstimulation upon the ear have been handicapped by lack of an audiometric procedure known to detect subtle changes in the organ of Corti. Fatigue has often been suggested and used but studies of the cochlear potentials associated with low-intensity vibration of the organ of Corti have never revealed such fatigue, which must arise from more central structures. Fatigue following high levels of sound intensity is probably a sum of “neural” fatigue and an injury to the organ of Corti. On the other hand, such studies have shown aural overload to result from an overdriving of the organ of Corti beginning at an intensity of sound considerably below that which is injurious.

The experiments reported here compare the shift in audibility threshold and in onset of overload following one-minute stimulations with a 1000-cps tone at sensation levels of 20, 60, 80, 90, 100, and 110 db. The amount of post-stimulus fatigue measured 6 seconds after cessation of the fatiguing tone showed little variation with intensity of fatiguing tone whereas the onset of overload, when compensation was made for fatigue of the harmonic frequency, showed a progressive lowering with increase of intensity of fatigue tone.

It is concluded that within the limitations of these experimental conditions the fatigue measured is not a property of the sensory cells whose sensitivity does not change until an injurious level of tone is reached, but that overloading is a property of these cells and the lowering of its onset level reflects an increasing decrement in performance following increasing intensities of stimulation.
Electrophysiological Evidence for Auditory Sensitization
Authors: Hughes John R. , Rosenblith Walter A.
Published: September 2005

This study was designed to investigate the properties of the first neural response (N1) to tone pips; the responses were recorded from the round window of the cat. Amplitude, latency, and adaptation (equilibration) curves were studied. The major part of the investigation was concerned with the effect of low-tone exposure on the amplitude of the N1 response to tone pips. After a relatively intense exposure, the amplitude of the N1 response, compared with the pre-exposure level, shows an initial subnormality (decreased response), a sensitization (increased response), and then a second subnormality. Sensitization was found when the exposure tone was the same, higher and lower in frequency than the basic frequency of the test tone pip. Exposure to low-frequency noise gives rise to a monotonic recovery process; i.e., a subnormality without subsequent sensitization. Contralateral effects were not detected. This sensitization of the N1 response is compared with related psychophysical data and may be regarded as an example of post-tetanic potentiation.

Psychophysical experiments [J. R. Hughes, Ph.D. thesis, Harvard University (1954) and reference 19] have demonstrated the existence of “auditory sensitization” (a lowering of the absolute threshold for pure tones after low-tone exposure). After a relatively intense exposure, there is a brief rise in threshold, then a sensitization which lasts for approximately 2 min, followed by a long-lasting second rise in threshold. This psychophysical study also demonstrated that a relatively wide range of exposure frequencies can sensitize the auditory system to a given test tone pip.

In order to obtain comparable evidence for sensitization in the electrical activity of the auditory nervous system, electrophysiological experiments were conducted on cats. The present study was designed to investigate the effect of a pure-tone stimulus on the properties of the first neural response (N1) recorded from the vicinity of the round window of the cat's cochlea. The major part of the investigation was concerned with whether, after low-tone exposure, the N1 response exceeds in amplitude the pre-exposure value: this phenomenon, when it occurs, will be labeled “sensitization of N1.”

These electrophysiological studies on sensitization may be related to post-tetanic potentiation (PTP) (see references 11 and 21); this possible relationship will be discussed later. PTP refers to the increased responsiveness of the nervous system after application of a tetanizing stimulus.
Influence of Noise upon the Equivalence of Intensity Differences and Small Time Delays in Two-Loudspeaker Systems
Authors: Leakey D. M. , Cherry E. Colin
Published: September 2005

The equivalence of intensity difference and time delay in two-loudspeaker systems is greatly affected by the presence of extraneous noise. An experiment is described in which this effect is measured with speech and wide-band noise. It is found that as the noise level is increased the equivalent intensity difference, for a given time delay, decreases, tending to zero for noise levels approaching the masking level.
Diffraction of Light by Ultrasonic Waves of Various Standing Wave Ratios
Authors: Cook B. D. , Hiedemann E. A.
Published: September 2005

The theory for the diffraction of light by plane ultrasonic waves of various standing wave ratios is derived. The liquid medium disturbed by the ultrasound is considered to act as an optical phase grating. By evaluating the diffraction integral for the light amplitude, expressions for the Doppler shift, the time dependent, and the time average light intensities are found for the diffraction spectrum. Experimental measurements using two adjacent ultrasonic waves progressing in opposite directions to simulate the desired optical phase grating indicate that the theory is valid.
Elastic Wave Mode Conversion at a Solid-Solid Boundary with Transverse Slip
Authors: Kühn G. J. , Lutsch A.
Published: September 2005

If two solids are coupled to each other through a liquid layer, transverse slip can occur at the boundary surface when an elastic wave is incident on the boundary. Algebraic expressions for the amplitudes of the various wave modes are derived on the assumption of transverse slip at the boundary, and these are compared with wave mode amplitudes for a solid-air boundary. Experimental measurements in connection with the design of an indicator for the degree of coupling between an angle probe and a test object are explained on this assumption. Curves are given showing wave-mode amplitude for: (i) Plexiglas-air boundary; (ii) Plexiglas steel boundary assuming transverse slip; (iii) Plexiglas steel boundary assuming rigid contact.
Solution of an Integral Equation Occurring the Study of Certain Wave-Propagation Problems in Layered Media
Authors: Longman Ivor M.
Published: September 2005

This paper describes a method of inversion of an integral equation arising the solution of the problem of reflection or refraction of a spherical sound-wave pulse at a plane interface a layered elastic medium. The solution of this integral equation is equivalent to obtaining the inverse Laplace transform of the operational solution of the problem.
Rayleigh Waves in a Porous, Elastic, Saturated Solid
Authors: Jones John P.
Published: September 2005

The equation for the velocity of propagation of Rayleigh-type surface waves in a porous, elastic, saturated solid is derived and discussed. The inertia coupling between fluid and solid is neglected, and Darcy's coefficient is taken to be independent of frequency.
Absorption of Sound by Patches of Absorbent Materials
Authors: Cook Richard K.
Published: September 2005

Circular patches, or long strips, of sound absorbent material are on the surface of an infinite perfectly reflecting plane. Exact solutions are found for the absorption of perpendicularly incident plane waves, and of randomly incident waves, on a circular piston-like absorber. An exact solution is found for the absorption of perpendicularly incident plane waves on an infinitely long strip-piston absorber. The basis of the technique is representation of the total wave field by superposition of an incident plane wave, a specularly reflected plane wave, and a scattered wave. The last-named is in turn represented by a superposition of plane waves for the strip piston, and by a superposition of cylindrical waves for the circular piston absorber. The superposed wave fields are adjusted to meet the boundary conditions.
Effect of Matching Time on Perstimulatory Adaptation
Authors: Small Arnold M. , Minifie Fred D.
Published: September 2005

Widely divergent amounts of perstimulatory adaptation have been reported previously, possibly due to differences in technique of measurement. One method often used determines perstimulatory adaptation from a series of simultaneous binaural loudness balances between a continuous stimulus in the adapting ear and a stimulus intermittently presented to the test ear. The present study attempts to evaluate the effect of the characteristics of intermittency of the test stimulus upon the measured adaptation in the adapting ear. With a 4000-cps adapting tone presented at 75-db sensation level, 16 combinations of on- and off-duration of the test tone were investigated using 11 listeners. For all experimental conditions the adapting curves showed the same general shape, with a rapid initial decline, followed by a more gradual decline reaching asymptote after 5 to 6 min. As the on-time of the test stimulus increased, less adaptation was seen, except for off-times of 30 sec or greater where on-time no longer influenced adaptation. This is interpreted as indicating that greater amounts of adaptation took place in the test ear as on-time was lengthened; but for the stimuli used, 30 sec was sufficient for recovery to occur. In general, however, variation in on-time produced greater changes in measured adaptation than did similar changes in off-time of the test stimulus.
Studies on the Aural Reflex. I. Contralateral Remote Masking as an Indicator of Reflex Activity
Authors: Ward W. Dixon
Published: September 2005

The phenomenon of “contralateral remote masking” is described: the elevation of threshold sensitivity to a low-frequency tone in one ear produced by a high-frequency band of noise in the other. Evidence is presented indicating that this effect is mainly attenuation induced by reflex activation of the stapedius muscle, although probably some central masking is also involved. The strength of the activation (1) increases linearly with sound pressure level of the arousal noise beginning at about 85 db SPL, (2) decreases linearly with frequency level of the noise, and (3) gradually decreases with time (i.e., adapts), reaching an asymptote after about 3 min. Individual differences in reflex activity could not be explained in terms of differences in resting thresholds. The relation of this phenomenon to ipsilateral remote masking and loudness adaptation is studied, and its effect on temporary threshold shift and on loudness judgements at high intensities is discussed.
Sequential Effects in the Signal-Detection Situation
Authors: Speeth S. D. , Mathews M. V.
Published: September 2005

This paper examines some sequential effects found in the behavior of observers in the signal-detection situation. The Tanner-Swets-Green model treats the subject as a stable decision maker operating on information from a noisy but unbiased transducer. It is suggested that this model may be profitably replaced by one in which a bias is introduced by a simple finite-state machine which makes the subjects' behavior a function not only of the present stimuli but also of past stimuli and responses.
Auditory Adaptation
Authors: Jerger James F.
Published: September 2005

The apparent decline in the ear's response under sustained stimulation, phenomenon which has been variously labeled “auditory fatigue,” “perstimulatory fatigue,” and “auditory adaptation,” was measured for pure tones over a wide range of frequencies and intensities by the median-plane-localization method.

For a given intensity, increasing the frequency from 125 to 1000 cps increased both the initial rate and maximum amount of adaptation. Above 1000 cps further increases frequency did not appreciably change the adaptation curves.

For a given frequency, increasing the intensity of the sustained stimulus also increased both initial rate and maximum amount of adaptation. The function relating adaptation, in db; to stimulus intensity was, in general, negatively accelerated.

The duration of sustained stimulation at which adaptation reached maximum value was related to both frequency and intensity.
Confirmation of the Normal Threshold for Speech on C.I.D. Auditory Test W-2
Authors: Corso John F.
Published: September 2005

The present study was undertaken to determine the threshold for speech intelligibility for normal ears on the Central Institute for the Deaf (C.I.D.) Auditory Test W-2. Data were collected on both right and left ears of 139 subjects, ages 18 to 24 years inclusive, showing negative otological findings, a maximal pure tone hearing loss of 5 db at 500, 1000, or 2000 cps, and a history of minimal noise exposure. The obtained mean threshold for speech, for all ears combined (N = 278), was 18.55 db re 0.0002 dyne/cm2, with a standard deviation of 4.46 db. These results confirm the normal value for the threshold of intelligibility for the spondaic words of C.I.D. Auditory Test W-2.
Transverse Oscillations of a Liquid Jet. II
Authors: Brackenridge J. Bruce , Nyborg Wesley L.
Published: September 2005

A thin rectangular liquid jet impinges on the apex of a rigid wedge and, under suitable circumstances, sets itself into any of a number of modes or “stages” of steady-state transverse oscillation; any mode has associated with it a pattern of vortex production. Excerpts from motion pictures show sequences of jet configurations corresponding to the different modes of oscillation. In a photographic history depicting the buildings of oscillations in an initially quiescent jet, particular interest is attached to the fact that oscillations appear before vortices have developed. Observations from these photographs and results from an earlier paper are compared with predictions of recent theories of edge tone production.