bluuebunny/crossref_metadata_2025_split huggingface dataset:
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.
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.
Formulation of Wave Propagation in Infinite Media by Normal Coordinates with an Application to Diffraction
Authors: Biot M. A. , Tolstoy I. 
Published: September 2005

In the theories of acoustical and electromagnetic vibrations of enclosures, as well as in field theory and electrodynamics, one quite commonly uses normal modes as generalized coordinates in Hilbert space. Here the method is extended to unlimited or partially limited mechanical media, essentially by first solving the problem for an enclosure and going to a limit while expanding all or some of the boundaries to infinity. This leads to a very useful technique, of somewhat more generality than analogous procedures used in field theory. Thus it is applicable to all non-dissipative mechanical continua, for any boundary conditions, irrespective of the order or number of differential operators describing the continua and regardless of whether the coordinate systems are separable or not.
A general orthonormality condition valid in all such cases together with the necessary rules for dealing with divergent normalizing coefficients are easily obtained by limiting procedures. An equally general formulation for arbitrary sources is obtained from the principle of virtual work. The method is illustrated by simple examples, for the case of a point source representing the instantaneous injection of a unit volume, i.e., an idealized, infinitely rapid, explosion. It is shown that in the problem of diffraction by a rigid wedge or corner one is led very quickly to an explicit solution in closed form, involving elementary functions only. Some physical implications of this solution are mentioned briefly. The advantages of the normal coordinates method are discussed when thus used in propagation or diffraction problems in unlimited or partially limited mechanical continua. Obvious advantages are its generality, its flexibility in dealing with arbitrary sources, and the fact that it leads directly to the progressive transient solution.
Dynamic Magnetostrictive Properties of Ni-Fe Alloys
Authors: Davis C. M. , Helms H. H. , Ferebee S. F. 
Published: September 2005

The dynamic magnetostrictive properties of Ni-Fe alloys containing from 35% to 67.5% nickel were investigated to determine their suitability for use in electromechanical transducers. The material, in the form of toroids made from ring laminations, was evaluated by the motional impedance method. Annealing temperatures were varied from 600°C to 1220°C, and the effect of various annealing techniques was investigated. Measured values of the electromechanical coupling coefficient, the reversible permeability, the dynamic magnetostrictive constant, and other parameters are given.
The electromechanical coupling coefficient for alloys containing from 40% to 52.5% nickel was greater than 0.31. A maximum value of 0.37 was found for the 40% nickel alloy. The product of the magnetostrictive constant and the reversible permeability for the above range of alloys was greater than 95×104 (dynes/oersted-cm2) and reached a maximum value of approximately 130×104 for the alloy containing approximately 40% nickel.
On the Realization of a Linear Graph Given Its Algebraic Specification
Authors: Auslander L. , Trent H. M. 
Published: September 2005

The following problem is discussed in this paper. Given an algebraic specification of an oriented linear graph in the form of a branch-mesh or branch-node matrix on any arbitrary basis, how does one proceed systematically to construct the graph? This rather basic problem has been considered by other authors and a few procedures have been described in the literature. On closer examination the problem is not simply one of finding any old procedure that will work but rather a question of finding an efficient procedure in terms of the time required by an analyst to carry through the computation. A new procedure is described which is believed to be quite efficient. This procedure is simple since matrix manipulations are limited primarily to the deletion of rows and columns and the other main manipulation is that of freehand drawing.
The procedure is based upon the Decomposition Theorem published earlier and involves the notion of dividing a large graph into a sequence of small ones. A reassembly process then yields the desired result.
Simultaneous Two-Tone Pitch Discrimination
Authors: Thurlow W. R. , Bernstein S. 
Published: September 2005

The frequency separation between two simultaneously sounding tones necessary to give perception of two pitches has been investigated. Frequency levels of 200, 1000, 4000, 6000, and 10 000 cps were used. For the two-ear condition (where one tone was led to one ear, the other tone to the other ear), no striking differences were found between results at sensation levels of 10, 30, and 50 db. When both tones were led to the same ear, results tended to approach the two-ear situation when masking and interaction effects were minimized.
The relation of the two-ear results to localization is discussed. Finally special phenomena are described which arise when two low frequencies, related by simple multiples, are used in the two-ear situation.
Microbubble Persistence in Fresh Water
Authors: Turner W. R. 
Published: September 2005

Preliminary research confirms that microbubbles become stabilized in a body of water and persist for long periods of time in contradiction of classical theory. The evidence was obtained by generating bubbles at the bottom of a water tank and then measuring the decay of ultrasonic attenuation as bubbles of various sizes rose to the surface. Comparison of experimental and classical decay curves disclosed persistence that appeared to be a function of the solid particle content of the water and indicated that bubbles may stabilize at sizes as large as 30 μ radius in water of high particulate content. In waters of low particulate content the decay of attenuation lasted over 100 hr.
Substantial persistent abnormal attenuation was detected in all fresh tap water measured, amounting to a minimum 44% over that of distilled water (at 5.125 Mc) and is believed to be caused by stabilized bubble nuclei somewhat less than 0.8 μ in size. An interesting discovery was that attenuation rose in an uncovered test basin but fell in a covered basin, indicating that microbubbles may enter water on dust particles.
A hypothesis presented to explain the persistence effect suggests that solid particles collect on the bubble surface, forming a compressed wall capable of supporting the excess pressure necessary to halt gas diffusion. Other hypotheses explore the mechanism by which dust particles may carry air globules below the water surface, and the dynamics of microbubble populations.
Research on the Acoustic Air-Jet Generator: A New Development
Authors: Brun E. , Boucher R. M. G. 
Published: September 2005

The structure and operation of the Hartmann air-jet ultrasonic generator has been reviewed critically, and modifications are described which substantially increase the efficiency and available power output of the original device. Experimental results are presented in confirmation of the theoretical analysis.
An important part of the development has been the employment of a secondary resonator and projecting exponential horn. A novel design using a large number of whistles in a single horn (Multiwhistle R.B.) is described. This unit has a wide frequency and power range, and has been employed in France for agglomeration of aerosols, ultrasonic drying, fog dispersal, and other interesting applications.
Ultrasonic Atomization of Liquids
Authors: Lang Robert J. 
Published: September 2005

An experimental study was made of the mechanism by which the ultrasonic vibration of liquid surfaces causes atomization.
At exciting frequencies in the range of 10 to 800 kc, uniform patterns of crossed capillary waves were found on the liquid surface when atomization occurred. The number-median diameter of the particles produced was found to be a constant fraction, 0.34, of the capillary wavelength; the capillary wavelength is calculable by Kelvin's equation using the exciting frequency and properties of the fluid being atomized.
The evidence is strong that the mechanism of ultrasonic atomization involves the rupture of capillary surface waves and the subsequent ejection of the wave peaks from the surface as particles.
Influence of Shock-Machine Loading on Shock Spectra
Authors: Luhrs H. N. , Spence H. R. 
Published: September 2005

The influence of loading of a test item on a rigid shock-Machine platform was investigated to determine whether any peaks or notches are introduced into the acceleration shock spectrum which would cause excessive over or under testing at various frequencies. The results showed that the shock spectrum for a terminal peak saw tooth pulse is quite insensitive to shock-machine loading. The very low frequency end (below 100 cps for a 6-msec pulse) is most influenced, whereas the higher frequencies are virtually not influenced at all. The results also showed that even for a very high loading condition the primary spectrum is in all cases less severe than the residual spectrum.
Curves have been generated to depict both the primary and the residual spectrum for various resonators to shock platform mass ratios, for the case of a terminal peak saw-tooth pulse. This particular shock pulse is of interest since the resulting shock spectrum satisfies the requirements of a number of U.S. Air Force missile electronic equipment specifications.
Attenuation of Ear Protectors by Loudness Balance and Threshold Methods
Authors: Hershkowitz Joseph , Levine Leo M. 
Published: September 2005

The attenuations of two earmuffs and two earphone sockets were measured by three methods. Two of these methods used a loudness-balance procedure in which the subject, upon removal of the ear protectors, adjusted the ambient sound level to match the loudness to that which existed previously. This procedure was used with half-octave bands of thermal noise in a diffuse sound field and also with pure tones in free-field. The third method was the absolute-threshold-shift method using pure tones in free field and a clinical audiometric procedure.
At the low and high frequencies, results of the threshold method indicated an average of six decibels greater attenuation than was measured by the loudness-balance thermal noise diffuse field method. Since the latter method simulates actual usage more closely than the former, it is recommended that a safety factor be applied to threshold results in estimating the protection afforded in high noise ambients by earmuffs and receiver sockets.
Sound Velocity and Attenuation in Bubbly Mixtures Measured in Standing Wave Tubes
Authors: Silberman Edward 
Published: September 2005

Experimental measurements of sound velocity and attenuation constant in a mixture of air bubbles in fresh water, using a standing wave tube, are described. Bubble sizes in the mixtures were controlled between about 0.08- and 0.26-in. diameter, concentrations ranged from 0.03 to 1%, and applied frequencies from 60 to 20 000 cps. Bubbles in each mixture were of a single uniform size except for one series of experiments in which mixtures of bubbles of two discrete sizes were used. Attenuation constants were obtained for each mixture through a range of frequencies, including natural frequencies of the bubbles in the mixture. Velocity measurements were not obtained near the natural frequencies of the bubbles because high attenuation prevented the establishment of standing waves.
Data obtained in the tubes were reduced to mean, infinite conditions and compared with available theory. The measurements show that theory gives at least a good estimate of both velocity and attenuation constant in the region investigated.
Condenser Earphones with Multiple Layers of Solid Dielectric
Authors: Sessler G. M. , West J. E. 
Published: September 2005

A condenser earphone with multiple layers of thin solid dielectric material between a metal backplate and a metallized foil is described. The multilayer system has the advantage of providing a more uniform air-cushion between the electrodes, thus increasing efficiency and decreasing distortion.
The frequency response of this earphone has been measured on a standard 6-cm3 coupler. The response is flat within ±1.5 dB between 25 and 14 000 cps and within ±3 dB between 20 and 16 500 cps. In this frequency range the harmonic distortion is less than 1% and the intermodulation distortion is less than 3% at 100 dB SPL. Because of the phase linearity, the pulse response of the earphone is an almost true image of the applied voltage for pulses not containing frequencies above 15 000 cps.
The frequency response of the earphone has also been measured at seven human ears by the outer-ear canal method. The individual frequency response is flat within ±7 dB from 70 to 14 000 cps. For any one frequency, the sound-pressure deviation between individual ears is within ±6 dB.
The high quality of this earphone makes it useful for many purposes where preservation of signal wave-form is important, particularly in psycho-acoustic experiments.
Perception of Steady and Intermittent Sounds with Alternating Noise-Burst Stimuli
Authors: Thurlow Willard R. , Marten Anita E. 
Published: September 2005

Bursts of high-pass filtered thermal noise coming from two different sources in space were alternated in time (with no time gap between bursts). Separation angles between sources from 5 to 50 deg were used, and alternation rates from 2 to 14 per sec. Duration of bursts was also varied. Subjects indicated for each sound perceived whether it was steady or intermittent, and where it was located.
When the angle between sources is small, some subjects may hear only one continuous sound, provided that the repetition rate is relatively high. More commonly, however, our subjects tend to hear one steady sound and one intermittent sound when the separation angle between sources is small; they tend to hear this pattern at wider separation angles when the duration of one of the stimuli is short. When one of the bursts has short duration, and sources are separated by 30 to 50 deg, it appears to many subjects that the short burst is markedly displaced in location. For wider angles of separation between sources, and various conditions of duration, many subjects can also hear a third steady sound between the other two. Occurrence of this latter sound has especially interesting implications for a theory of sound-localization mechanisms.
Thermal Relaxation in Oxygen with H2O, HDO, and D2O Vapors as Impurities
Authors: Henderson Malcolm C. , Clark Anna Vincent , Lintz Paul R. 
Published: September 2005

Using the 100% relative-humidity technique for controlling the mole function of water vapor, the Napier (relaxation) frequency of oxygen has been measured as a function of the mole fraction of various water vapors, consisting of pure H2O, pure D2O, and three mixtures thereof. Pure H2O gives, as is well known, a quadratic in H, the mole fraction; pure D2O gives a linear relation down to 0.7×10−3. The mixtures show a linear relation above 1.5×10−3 and a curvilinear approach to zero below that. Calculation indicates that the heterogeneous molecule HDO is far more effective as a thermal equilibrator for oxygen than either of its homogeneous parents. Quantitatively, with (f/p)m in cps per atm and h in mole fraction ×103, the results are:
100% H2O: (f/p)m = 7+183h+132h2;
50% D2O: (f/p)m = −664+1100h;
80% D2O: (f/p)m = −490+908h;
92% D2O: (f/p)m = −250+585h(above h = 1.3);
92% D2O: (f/p)m = 7+275h+100h2(below h = 1.3);
99.8% D2O: (f/p)m = −85+385h.
Some Characteristics of the Flexural Vibrations of Orthogonally Stiffened Cylindrical Shells
Authors: Hoppmann W. H. 
Published: September 2005

The paper presents a résumé of a theoretical study of the problem of flexural vibrations of the wails of orthogonally stiffened cylindrical shells. Frequency equations are given for the stiffened shells. In addition an experimental method of verifying the theory is described. Experimentally determined frequencies for an isotropic as well as two different designs of orthogonally stiffened shells are given in tables. The experimental and corresponding theoretical results are discussed.
A peculiar dip in the frequency spectrum which was discovered by Arnold and Warburton for uniform isotropic shells is shown to exist theoretically and is verified experimentally for stiffened shells. In addition, there is shown to be a bias in the excitability of the modes of vibration as determined experimentally. The reason for this phenomenon is discussed.
The principal axes of stiffness are in the longitudinal and transverse directions for the shells under study. In one case the axis of maximum stiffness is in the longitudinal direction and in the other case it is in the transverse direction. As the stiffness tensor is the same for the two cases, except for orientation, an opportunity is provided for examining the effect of rotating the stiffness axes through 90°.
Difference Limen for Tone Diminution
Authors: Kirk Roger E. 
Published: September 2005

The difference limen for tone diminution was investigated with diminution rate, fundamental frequency, and tonal complexity as parameters. Electronic means provided two tones whose diminution rates were independently adjustable. The tones were alternately presented to subjects over PDR-8 earphones. The method of constant stimuli was used in determining the difference limen.
The relative difference limen for tone diminution is of the order of 412 to 512% over the range of diminution rates investigated. The difference limen is relatively independent of fundamental frequency and tonal complexity. The relationship between the difference limen and diminution rate is described by an equation of the form Y = 0.048X where Y and X are measured in db/sec.
Dependence of Temporary Threshold Shift at 4 kc on Intensity and Time
Authors: Ward W. D. , Glorig A. , Sklar D. L. 
Published: September 2005

The results of a series of studies, using normal ears, on the effects of broad-band noise (a noise having equal energy in all octave bands from 75 to 10 000 cps), can be summarized in two equations. The growth of temporary threshold shift (TTS) at 4 kc is given by TTS2 = 1.06R(S − 85)[log10(T/1.7)], where TTS2 is the TTS in db 2 min after cessation of a T-minute exposure to a noise having a sound pressure level (SPL) of S db; R is the fraction of the time that the noise is on. This equation holds for T&gt;5 min, 85&lt;S&lt;110 db (perhaps higher), and all values of R provided that the noise bursts are 250 msec to 1 min long. The recovery from 2-hour exposures is described by TTSt = TTS2[1−0.37 log10(t/2)], where TTSt is the TTS remaining after t minutes of recovery. This equation holds when t is 2 min or more, and when TTS2 does not exceed 50 db.
Thus the relation between intensity and duration for constant TTS at 4 kc is much more complicated than predicted by the equation IT = K of classical psychophysics, or the I12T = k recently suggested, although both are approximately true in particular regions. Furthermore, it is evident that a noise on only part of the time is much less dangerous than one on continuously.
Study of Some Cues in the Perception of the Voiced Stop Consonants
Authors: Hoffman Howard S. 
Published: September 2005

Previous research involving synthetic speech reveals that both the second- and the third-formant transitions play a role in the perception of the voiced stops, |b|, |d|, and |g|. The present experiment examined an additional cue (burst frequency), repeated a portion of the previous research, and collected more information about how the cues act in various combinations.
Synthetic speech sounds containing one cue, all possible combinations of two cues, and all possible combinations of three cues were tested on a large group of listeners.
Burst frequency was found to act as a cue for the perception of the voiced stops in much the same manner as this variable affects the perception of the unvoiced stops. To the extent that the present experiment overlapped previous research, the two sets of findings were in very close agreement. When cues were combined, they shared in the control of perception in such a way that the contribution of any one cue was largely independent of the nature and the number of the other cues present in the sound. The individual cues seemed to have directional properties somewhat like vectors. The addition of cues produced effects somewhat like the addition of vectors.