bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the Stability of Random Systems and the Stabilization of Deterministic Systems with Random Noise
Authors: Samuels J. Clifton 
Published: September 2005

A general theory of mean square stability of random linear systems is developed when several system parameters vary as white noise stochastic processes. It is found that stability in mean square is determined from the character of the roots of a determinantal equation involving the Fourier transforms of double products of the weighting functions of the “average” system and the spectral densities of the parameter processes.
The general theory is applied to the mean square stability of an RLC circuit in which the resistance and capacitance have purely random fluctuations.
In the course of the study, a new type of dynamic stability is predicted, namely, the possibility of stabilizing unstable deterministic systems with random noise. Preliminary experimental studies appear to confirm this theoretical prediction.
Transient Interaction of an Acoustic Wave with a Circular Cylindrical Elastic Shell
Authors: Payton R. G. 
Published: September 2005

An infinitely long, circular cylindrical elastic shell is surrounded by an acoustic fluid. A plane pressure pulse, whose front is parallel to the axis of the shell, moves through the fluid, strikes the shell, and subsequently engulfs the shell.
The circular shell is replaced by a fictitious Riemann surface which effectively allows the range of θ (the angular coordinate) to be extended from − ∞ to + ∞. Exact expressions are then found for the subsequent shell and fluid motion in the form of double integrals by the use of integral transform techniques. These integrals are evaluated asymptotically by the method of steepest descent to determine the early time motion of the shell and fluid. In particular, it is found that during this early motion the radial shell velocity and bending moment have a maximum, and the fluid pressure at the interface experiences a minimum.
Masking of Tonal Signals
Authors: Jeffress Lloyd A. , Blodgett Hugh C. , Sandel Thomas T. , Wood Charles L. 
Published: September 2005

Many of the phenomena of masking can be explained on the basis of two models, one for monaural listening, and the other for binaural. The monaural model is the familiar narrow band-pass filter followed by a detector responsive to changes in output level. The binaural model is a series of coincidence detectors associated with a delay-network capable of matching delay in the stimulus with a delay in the neural path.
The two models have proved helpful in understanding the phenomena of tonal masking, and have led to a number of predictions which have been subsequently verified by experiments reported here. Some of the new findings are related to monaural masking and some to binaural. Among the latter are the fact that masking-level differences can be observed in the masking of one pure tone by another when a short signal is employed, and that a binaural signal can be heard in the presence of uncorrelated noise at the two ears better than a monaural signal can be heard against noise presented monaurally, again provided that a short signal is employed.
Many studies of the masking of tones have appeared during the past few years. They have been characterized by close agreement in results wherever they have had common conditions, and they provide a large body of dependable quantitative information. With this body of fact there also grew, at least in the minds of present writers, a considerable state of bewilderment. Many of the facts appeared to contradict inferences drawn from others. The present paper discusses a number of these facts and attempts to encompass them under a few explanatory principles.
Sensitivity of the Water-Immersed Ear to High- and Low-Level Tones
Authors: Montague W. E. , Strickland J. F. 
Published: September 2005

Two experiments are reported regarding man's sensitivity to waterborne sound. The first study investigated the threshold sensitivity to tones of 250, 500, 1000, 1500, 2000, 3000, 4000, and 6000 cps and the attenuation due to the diver's hood. The second experiment obtained data on the “tolerance” to a high-intensity tone of 1500 cps.
The sound-pressure level needed to reach threshold in water is about 40–70 db higher than the MAP threshold in air. The greatest loss in sensitivity occurs in the regions of greatest air sensitivity. The diver's hood was found to provide about 20 db or more of attenuation of underwater sound at frequencies above 1000 cps.
The “tolerance” limits for hoodless divers is approximately 174 db re 0.0002 dyne/cm2. When wearing the hood divers were able to tolerate at least 180 db, the system's maximum output. Above 165 db all divers reported some distortion of the visual field.
Comments on a Recent Paper by Hueter et al. on Ultrasonic Lesions in the Central Nervous System
Authors: Fry William J. 
Published: September 2005

The recent paper by Hueter et al. on ultrasonic lesions in the central nervous system, which appeared in a recent issue of this Journal (March, 1956), presents a rather limited view of this field and may lead to some misunderstandings.
This note is a critical analysis of the Hueter paper. Some of the more important points discussed are: (1) The unique advantages of producing ultrasonic lesions in the brain by using dosages appropriate for selective action combined with focusing of the beam in contrast to the use of focusing alone. (2) The choice of an irradiation procedure in experiments designed for the elucidation of physical mechanisms of the action of ultrasound on tissue. (3) The specification of the acoustic variables required for a dosage description. (4) The inapplicability of Eyring's theory of viscosity, plasticity, and diffusion to the elucidation of observed dosage relations. (5) The clarification of the usage of the terminology, nontemperature effects. (6) The applicability of the reciprocity method for the calibration of thermo-couple probes.
Vortex-Ring Structure-Transition in a Jet Emitting Discrete Acoustic Frequencies
Authors: Anderson A. B. C. 
Published: September 2005

Visualization of the vortex flow pattern in typical jets emitting jet tones was made by means of shadowgraph techniques to show the nature of the ever present process of vortex coalescence in the jet and how this determines the values of the eigenton sound frequencies radiated by the jet. These frequencies are super-imposed on the noise background radiated by the jet. The dependence of (a) vortex shedding frequency from the orifice, (b) jet-tone frequencies, and (c) translational velocity of the vortices on Reynolds number (Re) is shown.
These studies were carried out with carbon dioxide jets discharging into the atmosphere. The flow channel geometry consisted of an orifice plate containing a sharp-edged, circular orifice, 0.250 in. in diameter and 0.093 in. thick attached to a large stilling tank partly filled with sound-absorbing material to eliminate any effects of cavity resonance on the jet. The studies were carried out over the range from Re zero to Re 7000, where Re = vρt/μ and v is mean velocity of discharge of jet; ρ, gas density; t, orifice plate thickness, and μ, gas viscosity.
Frequency of Edge Mode of Isotropic Thin Rectangular Plate, Circular Disk and Rod
Authors: Onoe Morio 
Published: September 2005

The frequency of the edge mode, which is closely associated with the complex branches of the dispersion equation, has been approximated by taking only the complex branches into account.
The frequencies for a thin rectangular plate, a circular disk and a rod have been evaluated as functions of Poisson's ratio and compared with the observed values by various investigators.
Resonant Displacement of Nickel and Permendur Magnetostrictors under Static Compressive Stress
Authors: Whymark Roy R. , Witting James M. 
Published: September 2005

Relative resonant displacement of bar magnetostrictors as a function of polarization at atmospheric stress and at a compressional, axial stress of 230 atm is measured. Laminated bars of nickel and 2V-permendur are driven at frequencies both at and well below the resonant frequency of the bars, about 23 kc. Measurements of the Q and the reversible permeability enable one to compare the magnetostrictive constants and the coupling at the two stress levels for both materials.
The resonant displacement was found to change only slightly upon application of the compressive stress, for polarizing fields up to 100 oe. The compressive stress increased the maximum coupling for permendur by about 10%, the stress decreased the maximum coupling for nickel by about 10%.
'Twixt Earth and Sky with Rod and Tube; the Mobility and Classical Impedance Analogies
Authors: Firestone Floyd A. 
Published: September 2005

The techniques which comprise the mobility analogy have been introduced into the classical impedance analogy. The mobility and impedance analogies are set forth in form for practical use. The completely dual character of these two analogies is rendered evident by placing the elements of the mobility analogy on a series of left-hand pages and the dual elements of the impedance analogy on the facing right-hand pages. In each analogy a set of mechanical and acoustical symbols is provided so that mechanical and acoustical schematic diagrams can be drawn without the necessity of drawing either of the analogous electrical schematic diagrams. These mechanical and acoustical symbols resemble somewhat their analogous electrical symbols so as to indicate to anyone familiar with circuit theory the algebraic operations which are to be performed in the analysis.
Whereas in an electrical schematic straight line represents an ideal wire, in a mobility schematic a straight line represents an ideal incompressible massless rod; in an impedance schematic a line represents a hydraulic tube filled with ideal massless incompressible liquid which can sustain either tension or compression.
Correct mobility schematics are obtained by inspection through considering each mass as having one terminal fixed in a frame of reference called the earth which has zero mobility and infinite mass and is analogous to electrical ground; correct impedance schematics are obtained by inspection through considering each spring as having one terminal fixed in a force of reference (P0, etc.) called the sky which has zero impedance and infinite compliance (in both cases the analogous electrical element is a conducting sphere in free space, not a condenser). Although it is recommended that analogous electrical circuits not be used in routine analysis, they can be copied directly from a mobility schematic by considering mechanical earth analogous to electrical ground, or copied directly from an impedance schematic by considering mechanical sky analogous to electrical ground.
Determination of the Elastic Constants of Optical Glasses by an Ultrasonic Method
Authors: Barnes James M. , Hiedemann E. A. 
Published: September 2005

The values of the elastic constants of twelve samples of optical glass commercially produced in the United States and a sample of fused silica were calculated from the results of measurements made on these samples. The method used was a combination of the ultrasonic method developed by Schaefer-Bergmann with that of Hiedemann.
The accuracies of the experimentally determined values of the longitudinal and shear wave velocities were 0.13% and 0.25%, respectively, while the accuracies in determining the elastic constants were 0.5% for the shear modulus, Lame's modulus, and the bulk modulus, 0.7% for Poisson's ratio, and 0.8% for Young's modulus. The values of the surface tensions of the samples were calculated using the results of the measurements and Auerbach's equation.
Effect of Visual Factors on the Intelligibility of Speech
Authors: Neely Keith K. 
Published: September 2005

Research has indicated the important role that vision plays in face-to-face voice communication. This study was an attempt to quantify further the visual contribution to speech intelligibility in a high intensity noise environment in terms of the angle and distance from the listener to the speaker.
Results indicated that (1) visual cues resulted in a significant increase in listener-intelligibility scores, (2) the angle at which the listeners observed the speaker influenced their listener-intelligibility scores, and (3) the distance of the listener from the speaker did not have a significant effect on listener-intelligibility scores within three to nine-foot limits.
The importance of speech-reading training and the use of visual cues is evident where face-to-face voice communication has to be conducted in high intensity noise environment.
On the Transmission of a Spherical Sound Wave through a Stretched Membrane
Authors: Lamb George L. 
Published: September 2005

The transmission of a spherical sound wave through a homogeneous stretched membrane of infinite extent is investigated theoretically. An integral representation of the transmitted sound field is initially derived. The path of integration is then transformed into the complex plane and the integration carried out in an approximate manner by the method of stationary phase.
The transmitted sound field is found to be composed of two parts, an outgoing spherical wave modified by an amplitude factor containing angular dependence and a surface wave. The surface wave, which results from the free flexural vibration of the membrane itself, exhibits an interesting “zone of silence” in the transmitted sound field.
Ultrasonic Pulse Technique for Measuring Acoustic Losses and Velocities of Propagation in Liquids as a Function of Temperature and Hydrostatic Pressure
Authors: McSkimin H. J. 
Published: September 2005

A fixed path ultrasonic unit operating in the frequency range of 20–200 mcps is described which can be used for measuring acoustic wave velocities and losses in liquids as a function of temperature and hydrostatic pressure. A simple phase balance technique insures a high order of accuracy for velocity determinations,
Illustrative data for carbon tetrachloride, Dow Corning DC-703 and DC-200 silicone fluids, and water are shown. Determination of freezing points of liquids using ultrasonic waves for indication is also discussed briefly.
Acoustical Field at Normal Modes in Rooms
Authors: Korn T. S. , Van de Plas R. 
Published: September 2005

The physical form of the acoustical field at normal complex modes in rooms can be represented as a set of elementary curvilinear ducts, each carrying a single stationary wave, satisfying individually the boundary conditions at the walls. In spite of the differences in their lengths, all the ducts resonate at the same nominal frequency, the differences in their flares adjusting the phase velocity along their axes.
This theory is confirmed by the analysis derived from the theory of horns. An experiment on the computed model of the duct yielded with good accuracy the calculated frequency of resonance.
Array Steering in a Layered Waveguide
Authors: Clay C. S. 
Published: September 2005

The usual way to determine the direction of a radiating source with an array is to steer the array for maximum output. The steering can be done by time delays or by mechanically turning the array. The output of the array can be expressed as the sum of the time average of the products of the pressure 〈PmPn〉, observed at detectors m and n. The value of 〈Pm(τm)Pn(τn)〉 can be maximized by a proper choice of time delays τm, τn. This procedure is straightforward in an infinite homogeneous medium. If the medium is a layered waveguide, there are many more possibilities for submaxima of the PmPn terms.
The normal mode solution of the radiation field of a band limited noise point source is used to calculate the acoustical pressures Pm and Pn. The value of 〈Pm(τm)Pn(τn)〉 as a function of time delay is compared with the value of PnPm obtained with mechanical steering. For these calculations, the noise source is assumed to have a bandwidth of one fifteenth of the center frequency, and the depth of the water is assumed to be about 2λ over a thick layer of unconsolidated sediment. The number of maxima of the 〈Pm(τm)Pn(τn)〉 is related to the number of modes propagating in the waveguide if the steering is done with time delays. Mechanical steering yields one maximum that corresponds to the source direction.
Plane Waves in a Thermoelastic Solid
Authors: Deresiewicz H. 
Published: September 2005

In an isotropic, thermoelastic solid shear waves are unaltered by thermal effects. However, two distinct dilatational waves exist, both of which are dispersed and attenuated by the medium. One of the waves (denoted the E wave) is close in character to the pure elastic wave, the other wave (denoted the T wave) is similar in nature to the pure thermal wave.
The properties of the two dilatational motions are studied and relations are given expressing the variation, in each, of phase velocity, amplitude attenuation, and specific loss with impressed frequency. For the E wave the result is verified that this disturbance propagates at the adiabatic velocity at low frequencies and at the isothermal velocity at very high frequencies. An explanation based on physical considerations is offered to account for this generally overlooked phenomenon. It is further found that the amplitude is attenuated exponentially as the square of the frequency at relatively low frequencies, but approaches finite value as the frequency increases without limit. The specific loss reaches maximum for the E wave, a minimum for the T wave, near the frequency whose period is equal to the relaxation time due to thermal currents.
Finally, the ratios are computed of the amplitude of the temperature to the amplitude of the displacement in each of the two modes of motion. Numerical work indicates that, for metals at room temperature, the effect of coupling between elastic and thermal motions is very small.
Detection of Auditory Sinusoids of Uncertain Frequency
Authors: Green David M. 
Published: September 2005

The decrease in the detectability of a gated sinusoidal signal in noise caused by deliberately introducing uncertainty about the signal's frequency is no greater than 3 db, even in an extreme condition of uncertainty. In this extreme condition the signal duration is 0.1 sec, and the signal frequency is varied between 500 and 4000 cps. This effect is not critically dependent on signal duration. Moreover, the observers not only detect the signal but display at least gross information about the frequency of the signal in the uncertain frequency conditions.
Several models, suggested in previous studies, are considered. The magnitude of the decrease observed in the data falls far short of the predictions of these models. An interpretation suggested by the data is that the observers in a detection task, even when a signal of fixed frequency is used, are highly uncertain as to the exact physical parameters of the signal. Another way of stating this assumption is to say that the observer never tests for the presence or absence of a signal on the basis of one simple hypothesis. From this assumption we should expect little decrease in detectability from deliberately introducing frequency uncertainty. This interpretation would suggest the same result would be obtained if time were the major experimental variable.
Modes of Vibration of the Indian Drum Dugga or Left-Hand Thabala
Authors: Ramakrishna B. S. 
Published: September 2005

The dugga or the left-hand thabala is a companion drum to the right-hand thabala and the two together are widely used in India. The vibration characteristics of the latter which has a symmetrically loaded membrane were discussed previously where it was shown how this drum produces harmonic overtones.
The left-hand thabala also has a loaded drumhead, but the loading is here eccentric. The boundary value problem of this drumhead is not separable, and hence there is no readily available method for computing its characteristic frequencies. An approximate theory for computing the frequencies of the lower modes is here developed under the assumption that for these modes the effect of the (unloaded) annular region on the loaded region may be replaced by a suitably determined elastic support around its boundary. This leads to the boundary value problem of a membrane with an elastic boundary support whose stiffness constant per unit length is a function of the polar angle. The problem is still unseparable, but the eigenvalues can be now computed by a boundary perturbation technique from those of a membrane with a boundary support of constant stiffness. Computed and measured frequency ratios agree within seven percent or better.
Improved Quasi-Stereophony and “Colorless” Artificial Reverberation
Authors: Schroeder M. R. 
Published: September 2005

“Quasi stereophony” is defined as the reproduction over two or more loudspeakers (or binaural earphones) of different sound signals derived from a single audio signal. The purpose of quasi-stereophony is to create (from a single audio signal) an illusion of spatially distributed sound sources. Quasi-stereophonic reproduction does not permit correct localization but does share with true stereophony the properties of “depth” and “ambience” which are important attributes of stereophony (for the casual listener perhaps even more important than correct localization).
This paper describes a new filtering method for producing quasi-stereophony. In contrast to earlier proposals, the new filtering method leaves the amplitude spectrum of the sound intact. The same kind of filter has also been used for generating “colorless” artificial reverberation. Experimental results indicate that both quasi-stereophony and artificial reverberation can be achieved without spectral distortion.
Radiation Force on Bodies in a Sound Field
Authors: Olsen Haakon , Romberg Werner , Wergeland Harald 
Published: September 2005

A simple derivation of the force which acts on a body placed in sound field is given. The tensor properties of the force are exhibited, but it is also shown that for a rigid body the force may be derived from the scalar pressure alone. It is shown how the time average force is determined by the momentum lost by the sound wave during the collision with the body. Using this result, the force is related to the scattering amplitude, and a simple expression in terms of the phase shifts is given.
The connection between the force and the scattering cross section is examined. A force factor κ = K̄z/(12ρ0k2σsc) is defined. It is shown that κ = 1 for plane scatterers perpendicular incidence. A simple general formula for the force in the limit of short wavelengths is derived. It is shown that neither for very long wavelengths nor for very short ones is κ in general equal to 1.
The case of a rigid sphere is treated in detail. Curves are shown for the force and for the force factor κ.
Localization of Aural Harmonics along the Basilar Membrane of Guinea Pigs
Authors: Tonndorf Juergen 
Published: September 2005

Harmonic distortion has been shown to originate hydrodynamically in cochlear models; its essential manifestation being Békésy's “eddies” and their sequelae. One of the major postulates derived from this study was that the distortion be resolved along the cochlear partition in accordance with the place principle of frequency localization.
Experiments on guinea pigs were conducted in an effort to support this latter postulate. A method of recording cochlear microphonics by means of differential electrodes was chosen. This method had been previously used by Tasaki, Davis, and Legouix for mapping amplitude and phase alteration along the basilar membrane.
The results of the present study indicate (1) that distortion within the cochlea occurs at a lower intensity level than it does in the middle ear (confirming results of earlier investigators), and (2) that each newly created harmonic forms a traveling-wave pattern of its own along the basilar membrane in accordance with the place principle. These results support the hydrodynamic hypothesis of the origin of intracochlear distortion.