bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrical Excitation of Nerves in the Skin at Audiofrequencies
Authors: Anderson Attell B. , Munson W. A. 
Published: September 2005

This is a report of results obtained in preliminary tests of perception of signals applied directly to the skin in the form of electrical potentials. The lowest signal level that could be felt and the highest level that could be applied without extreme discomfort to the observers were determined for sine wave potentials ranging from 100 to 10,000 cps. The difference between the lowest and highest levels was about 25 db over this frequency range.
Difference limen measurements for intensity and frequency showed that intensity discrimination is not greatly different from what it is for hearing, but the ear is vastly superior in the matter of frequency discrimination.
Some Recent Work on Auditory Adaptation and its Relationship to the Loudness Recruitment Phenomenon
Authors: Hallpike C. S. , Hood J. D. 
Published: September 2005

In the course of previous investigations, Dix, Hallpike, and Hood have concluded that the phenomenon of loudness recruitment is attributable to disordered function resulting from injury or disease of the hair cells of Corti's organ.
In the present paper, an account is given of an experimental study of certain loudness changes caused by adaptation of the hair cell responses to pure tone stimulation.
Two outstanding characteristics of the adapted state are defined: “on-effect normality” and “relapse.” Both resemble very closely those described by Matthews in the case of adaptation occurring the muscle stretch receptors of the frog.
Further studies in a number of human subjects show that both of these characteristics are exhibited regularly by the unadapted hair cell responses of individuals suffering from degenerative changes of the hair cells.
These studies appear to establish a very close similarity between “on-effect normality” occurring in the case of the adapted normal sense organ and the phenomenon of loudness recruitment, as demonstrated by the alternate binaural loudness balance procedure of Fowler in the case of the unadapted but diseased sense organ.
The experimental findings are considered to favor the view that loudness recruitment is one element of a complex disturbance of cochlear function due to disease or injury of specific elements of the cochlear sensory apparatus, namely the hair cells of Corti's organ.
Some Remarks on the Modern Status of Auditory Theory
Authors: Wever Ernest Glen 
Published: September 2005

A discussion is made of two lines of evidence that bear upon the problem of the relative importance of place and frequency principles in auditory theory. The first line of evidence has to do with the relation between pitch discrimination and the degree of specificity of action in the cochlea and brings us to an evaluation of the principle of maximum stimulation. A consideration of loudness discrimination data discloses a serious limitation on our ability to appreciate the point of maximum in the cochlear activity and, in general, to make use of a spatial pattern. We must conclude that for the low tones whose patterns are broad the place principle contributes little or nothing to pitch discrimination, and the frequency principle has to serve this function alone.
A study of the evolution of the ear brings out still more clearly the relative roles of place and frequency principles. Hearing in some degree is present throughout the vertebrate series, and even the lowest forms have frequency ranges of several octaves and exhibit a fair degree of tonal discrimination. Yet, these lower forms possess an ear of exceeding simplicity, an otic sac in which there is little evidence of mechanical differentiation. It follows that these primitive ears must operate as frequency receptors, with ranges and discriminative abilities that depend simply upon the patterns of impulses conveyed by the auditory nerve. It appears, therefore, that in the history of the ear the frequency principle came first as the basis of tonal reception, and only sometime later in the course of evolutionary development was it joined by the place principle.
Scattering and Absorption by an Acoustic Strip
Authors: Levitas Alfred , Lax Melvin 
Published: September 2005

A method for treating the scattering and absorption of sound in the presence of non-uniform boundary conditions is applied to the case of an infinite strip of material (of given width) placed on an infinite, otherwise hard, wall. The strip is assumed to be characterized by a normal acoustic impedance that may possess a resistive component.
The wave equation is reformulated as an integral equation over the strip. A variational expression is found for the amplitude of sound scattered by the strip in any direction. The total cross section for scattering plus absorption is determined from the amplitude of specular reflection according to a well-known cross-section theorem. Comparison with Pellam's results for absorption by such a strip shows that the methods used have an accuracy better than 2 percent over the entire frequency range.
Transmission of Sound through Steel Plates Immersed in Water
Authors: Fay R. D. , Fortier O. V. 
Published: September 2005

The measured transmittivity of a steel plate in water is presented as a function of the angle of incidence and the product of frequency and plate thickness over wide ranges.
The normal velocity of the plate surface can attain an amplitude necessary for good transmission only by constructive interference among internal reflections. It is shown that the ideal conditions can be met in a plate of finite width in only a few cases. In general, the conditions for a transmission maximum are the conditions for the existence of appropriate types of stable traveling waves in a plate of infinite extent; these conditions, however, are modified by edge effects. An apparent effect of this modification is to produce changes in the divergence of the transmitted beam and hence in the observed transmittivity.
Physical Factors Involved in Ultrasonically Induced Changes in Living Systems: II. Amplitude Duration Relations and the Effect of Hydrostatic Pressure for Nerve Tissue
Authors: Fry W. J. , Tucker D. , Fry F. J. , Wulff V. J. 
Published: September 2005

The results of experiments with frogs under a hydrostatic pressure demonstrate that cavitation is not an important factor in the mechanism of production of paralysis of the hind legs of frog by ultrasonic (frequency one megacycle) irradiation over the lumbar enlargement region of the spinal cord. Experimental results indicate that a linear relation exists between the reciprocal of the minimum exposure time for paralysis and the acoustic amplitude. This result is readily described in terms of a one factor rate process. On the basis of this experimentally determined relation, it is shown that time rate of change of temperature cannot be correlated with the observations. It is concluded on the basis of a theoretical calculation that absorption of ultrasound at interfaces in the spinal cord does not result in minute hot regions.
Further work on summation of subparalytic doses, spaced apart at various time intervals, indicates that the recovery process following exposure to a subparalytic dose of ultrasonic radiation may not be a monotonic function of time.
The Discontinuous Growth and Decay of Sound in a One-Dimensional Room
Authors: Miller Harry B. 
Published: September 2005

The growth and decay of sound in a one-dimensional room was investigated by using a very special room, namely, a helical spring. Compressional waves in the audiofrequency range were sent down the spring by an electromechanical driver and received at the far end by an electromechanical pickup. Reflection occurred at each terminal, allowing standing waves to be built up. The length of the spring was 30 in. and the transit time was 53.6 milliseconds, giving a propagation velocity of about 4612 ft/sec. The 30-in. spring is thus equivalent to a room about 58 ft long.
Oscillograms were obtained for frequencies below 100 cps, showing the discontinuous nature of the reverberation produced in the one-dimensional room.
During the analysis of the oscillograms, Eyring's mechanism of image sources was found to fail to explain some of the oscillograms. A new mechanism was therefore created, called the Two-Pipe Mechanism, which seems to explain all the oscillograms.
The Two-Pipe Mechanism clarifies: (1) the behavior of a normal mode when decay is started before steady state has been reached; (2) the growth and decay of standing waves on a violin string, by demonstrating the quantized envelope-levels which control this growth and decay; (3) the growth and decay of non-normal modes, by showing how decay can consist of the steady-state frequency alone, even though this is a “not-allowed” frequency.
Ultra Speed Recording for Acoustical Measurement
Authors: LeBel C. J. , Dunbar James Y. 
Published: September 2005

The technique and tests herein described were devised to study possible improvement in rating the acoustical excellence of rooms, by using higher pen speeds than had hitherto been available. Recordings of reverberation decay characteristics, made with the new ultra speed technique, are compared with results from older methods of recording reverberation; and it is found that the new method provides a much more adequate diagnosis of recognized acoustical faults.
The new technique makes possible ink recording of acoustical levels on a db basis at pen speeds of 5000 to 10,000 db per second, or ten to twenty times that afforded by the high speed level recorder. It uses a new stabilized logarithmic Varistor system for instantaneous conversion to a db basis, followed by a direct writing oscillograph. Hitherto unrecognized requirements for the electronic system are indicated as necessary if adequate stability, linearity, and scale range are to be achieved.
On the Dynamics of the Cochlea
Authors: Fletcher Harvey 
Published: September 2005

This paper is concerned with the dynamical behavior of the cochlea. It is assumed that a length of the basilar membrane which is equal to its width at each position vibrates as a unit, and that the forces exerted upon it by adjacent units are negligible compared to that exerted by the difference in pressure in the scala vestibuli and scala tympani. The boundary conditions at the stapes end is simply that the pressure difference in the two canals is equal to P0 any desired pressure difference. However, at the helicotrema the pressure difference must be equal to that between the two ends of the capillary opening at the helicotrema.
Then from the fundamental hydrodynamical equations and the experimental constants obtained by Békésy it is shown that the speed of sound through the liquid of the inner ear may be considered infinite compared to the speed of the wave along the basilar membrane. In other words, the liquid may be considered incompressible so that the rate of liquid displacement at the oval window is equal to that at the round window, and is also equal to that produced by flexure of the basilar for frequencies above 200 cps. Below this frequency some of the liquid goes back and forth through the helicotrema.
With these assumptions, the following quantities were calculated from the fundamental dynamical equations and found to be in good agreement with the experimental results of Békésy; (a) displacement amplitudes and phases of the basilar membrane at different distances from the stapes and for different frequencies, (b) time for wave to travel from stapes to various distances from stapes, and (c) volume displacement, at various frequencies, per dyne difference of pressure at oval window and that at round window.
Frequency Detection and Speech Formants
Authors: Peterson E. 
Published: September 2005

This study is aimed primarily at evaluating the utility of axis-crossing detectors in tracking speech formants. Detectors of the usual type are found subject to an error, fundamental in nature. To remove this source of error speech is modulated up in frequency as a single sideband before limiting and detecting processes are applied. Experimental results with this carrier type of detector on a small number of speech samples are presented, and compared with spectrograms.
Conclusions are that the average axis-crossing rates cannot be trusted in general to follow specific formants, whether the speech is normal or differentiated. But when the formants are sufficiently localized by frequency selectivity, prospects of tracking the lower formants look promising.
Field and Impedance of an Oscillating Sphere in a Viscoelastic Medium with an Application to Biophysics
Authors: Oestreicher Hans L. 
Published: September 2005

With an application to human tissue in view, a theoretical analysis of the behavior of mechanical vibrations in a medium with elastic, viscous, and relaxational properties is made. For this purpose, the equations of wave motion in a viscoelastic medium are discussed in general and solved for two problems, which are significant for the propagation and the transfer of vibrational energy: (1) energy propagation and absorption in plane waves, (2) field and impedance of an oscillating sphere.
The results show that the energy is propagated in two kinds of waves, the relative intensities of which change strongly with frequency: transverse waves, owing to the shear elasticity and viscosity, and compression (acoustical) waves, owing to the volume compressibility of the medium. A more detailed treatment is then accomplished for human muscle tissue by inserting the approximate values of its elastic constants into the general formulas, thus explaining the behavior in a frequency range from 0 up to several hundred kc.
Frequency-Band Multiplication or Division and Time-Expansion or Compression by Means of a String Filter
Authors: Vilbig Friedrich 
Published: September 2005

A frequency band multiplication or division has been performed by string filters. An exact relationship between the input and output frequencies has been shown. Two different methods have been used.
The first multiplies frequencies by rectification with the aid of a push-pull electrostatic pick-up. Alternating plus-minus polarizing techniques are employed to suppress the undesirable sum frequencies. The resolution of such a doubling system, which will not pass the sum frequencies, is approximately 1.5 times the band width of the single filters. However, the band width is limited by the transit time of speech.
The second method multiplies and divides by exciting the harmonics or subharmonics of the single strings. This is done by employing light, stiff “fingers” to disturb the free oscillations of the damped strings. The excitation and the resulting frequency band division and multiplication are investigated.
It is shown that in order to get time compression or expansion, it is only necessary to record the multiplied or divided frequency bands and play them back with the corresponding diminished or increased speeds.
The results given have a general application to similar type filters such as reed, crystal or magnetostrictive.
The Design of Optimum Directional Acoustic Arrays
Authors: Davids N. , Thurston E. G. , Mueser R. E. 
Published: September 2005

A transducer array has been designed according to underlying theory originally applied to broadside electromagnetic antenna arrays by Dolph. The properties of Tschebyscheff polynomials have been employed to obtain an optimized relationship between minor-lobe level and main beam width.
The shading design of a 130 element circular array is carried out utilizing a distance between stack centers of 5λ/8. Experimental measurements of the resulting transducer give a peak sensitivity of −70 db below 1 volt for a field of 1 dyne per cm2, 11 degrees main beam width at the 3-db down points, and suppression of side lobes to more than 32 db below peak sensitivity.
The Masking and Pitch Shifts of Pure Tones near Abrupt Changes in a Thermal Noise Spectrum
Authors: Webster J. C. , Miller P. H. , Thompson P. O. , Davenport E. W. 
Published: September 2005

When a pure tone is mixed with a noise of uniform spectrum, its threshold is raised. At levels above threshold, its loudness and pitch are changed by the presence of the noise. Introducing abrupt changes in the slope of the noise spectrum by filtering out (rejecting) one octave changes these effects in the vicinity of this gap.
The masked threshold for a pure tone varies from the value for unfiltered noise at the edges of the gap to a value approximately 25 db lower at the middle. This indicates that gapped-noise may be used to mask out sounds outside of the gap without unduly raising the threshold of sounds in the gap.
Presence of white noise.generally raises the pitch of a pure tone whose frequency is between 500 and 4000 cps. Presence of noise with the gap does not raise the pitch of a pure tone located in the upper half of the gap. For a tone located in the lower half of the gap, the pitch is raised more than it would be in the presence of unfiltered noise.
The changes in the judged loudness of pure tones partially masked by a gapped-noise reaffirm the importance of the tails of the excitation pattern in their effect on loudness.
Measurement of Dynamic Shear Viscosity and Stiffness of Viscous Liquids by Means of Traveling Torsional Waves
Authors: McSkimin H. J. 
Published: September 2005

A short periodically repeated train of torsional waves is transmitted along a glass or metal cylindrical rod. After reflection from the free end, these waves are sent back to the quartz crystal which serves as both transmitter and receiver. The phase shift and added attenuation caused by immersing the rod in the test liquid are measured by means of a special balancing arrangement, and yield a calculation of the impedance presented to the rod surface.
From an analysis of wave propagation both in the rod and in the liquid, one can calculate the characteristic shear impedance of the liquid, and the dynamic viscosity and stiffness.
Data for polyisobutylene liquids with static viscosities up to 2000 poises are given for the frequency range 25–150 kc. High frequency data (5–25 mc) for the same liquids obtained by a method previously reported on (see reference 10(b)) are correlated to the present work. Some results for polypropylene, polyisoprene, polybutadiene, and polypropylene sebacate are also given.
Tentative Estimate of a Hearing Damage Risk Criterion for Steady-State Noise
Authors: Hardy Howard C. 
Published: September 2005

The probable shape of a limiting spectrum for noise in a working environment where there is long daily exposure is determined by reasoning from previously determined data of the hearing mechanism. It is assumed that hearing loss is due to a progressive fatigue phenomenon, the fatigue being a direct function of the energy stimulus in the inner ear. From the characteristics of this stimulus as a function of frequency, it is shown that the most sensitive region for loss is around 3000 cps, the low frequencies being as much as 20 db less sensitive than this region. The 4000 cps “notch” in audiograms of industrial workers is thereby explained. The limiting spectra are essentially equal-loudness contours for broad-band noise when the noise spectrum is plotted in octave bands.
Two limiting loudness curves and their corresponding spectra are tentatively suggested as damage risk criteria. If the noise exceeds 100 sones in any octave band, it appears very probable that long time daily exposure will result in hearing damage and in a frequency region slightly above the frequencies of maximum stimulus. If the sound does not exceed 50 sones in any octave band, it appears to be unlikely that damage will occur even with long exposure. These criteria are confirmed by the few literature references which have enough data to be used. The need for more research to test these conclusions is emphasized.
Unsolved Problems Relating to Hearing Loss in Industry
Authors: Hoople Gordon D. 
Published: September 2005

Two generally accepted facts are: 1. Noise can cause hearing loss. 2. The noise which will cause a hearing loss in one individual may not be the cause of a hearing loss in another.
These immediately suggest two unsolved problems. 1. Why does a noise cause hearing loss in one person and none in another? 2. How much noise will cause a hearing loss?
The only logical answer to the first question must be that there is a variation in the sensitivity of ears to noise. Discovery of reliable tests which will predict which ear will be sensitive to noise and which will not, is an important unsolved problem, but if solved would do much to clear many disputed questions.
The answer to the second question, “How much noise?,” involves the following: the intensity of the noise, the kind of noise, the duration of the exposure to noise, the amount and character of the hearing loss which noise creates.
Noise in intensities of 120 to 150 decibels are conceded to be injurious to hearing. Noise less than 80 decibels is not a problem. Where between these two limits does noise become injurious to some ears? Noise with predominance of higher frequencies apparently is more injurious to hearing than one with predominance of low frequencies.
The length of exposure to noise depends upon so many factors that it is certainly an unsolved problem. The character of the loss is an injury to the nerve of hearing and presents no problem except the differentiation between loss due to fatigue and permanent hearing loss.
The paper ends with a plea for all who are interested to join in solving these questions so that noise can be less injurious to hearing.
The Physical Interpretation of the Expression for an Outgoing Wave in Cylindrical Coordinates
Authors: Junger Miguel C. 
Published: September 2005

The sound field generated by a vibrating cylinder of infinite length, whose dynamic configuration is periodic in φ and z, is expressed in terms of acoustic impedance ratios. It is noted that symmetrical modes of vibration are suppressed at certain frequencies because the corresponding reactive impedance is infinite, and that all z dependent modes become nonradiating below certain “cut-off” frequencies, the corresponding impedance being purely reactive. Graphs are presented for the impedance ratios corresponding to certain modes.
For modes independent of z, the sound field is in the form of concentric cylindrical waves. For z dependent modes, as the plane wave wavelength increases from zero to a certain critical cut-off value, the sound field changes from a set of concentric cylindrical waves to two sets of conical waves of decreasing vertex angle; at and beyond the cut-off point, the conical waves have degenerated into a set of plane standing waves normal to the z axis. Simultaneously, the sound field has ceased being periodic in the radial direction, and the phase velocity in that direction has become infinite.
Practical applications of these phenomena are suggested.
The Theory of Noise in Continuous Media
Authors: Eckart Carl 
Published: September 2005

It is shown that the mathematical solution of problems involving the propagation of noise is materially aided by the introduction of the space correlation function ψ(x1, x2, τ), defined as the average, over t, of p(x1t)p(x2t−τ), p being the acoustic pressure in the noise field. The differential equations satisfied by ψ are derived. Its relation to Ψ(α, β, γ) is discussed, α, β, γ being the propagation vector of a sinusoidal wave, and Ψ/2ρc2 being the density of potential energy in the α, β, γ space.
The theory of uniform noise fields, both isotropic and anisotropic, is developed in detail. The anisotropy caused by a reflecting plane is discussed. The radiation of noise by a vibrating plane is discussed, neglecting the reaction of the radiation on the motion of the surface. In particular, it is shown that to this approximation the sea surface cannot radiate subsonic energy into the high atmosphere because the velocity of the surface gravity waves is less than the velocity of sound in air.
The theory of noise, as here developed, is analogous to the theory of turbulence, and the relation between noise and turbulence is briefly discussed.