bluuebunny/crossref_metadata_2025 huggingface dataset:
Research Potentials in Auditory Characteristics of Violin Tone
Authors: Boomsliter Paul C. , Creel Warren
Published: October 2005

Sensations of tone, including violin tone, come partly from evoked matrices generated within the brain. Cited evidence from electrodes permanently implanted in the brains of conditioned cats shows that an incoming signal evokes generation of temporally patterned recurrences. The cat acts appropriately for the signal when coincidence exists between the input and the internally generated pattern. An adequately functioning nervous system experiences tone from input of regularly repeating waves, such as are compatible with neural temporal recurrence, but human patients with some neural handicaps, including vertebral artery insufficiency, commonly experience noise instead of tone from smooth sine wave input, presumably because of inadequate internal generation or coincidence detection. The normal human nervous system, with many neurons responding only to change, is not a steady-state apparatus, yet it uses temporal recurrence with an appetite for regularity. Human preference for regularity and change can be observed when a master plays a violin which is thus physiologically controlled.
Theory of Acoustical Wave Propagation in Porous Media
Authors: Smith Peter G. , Greenkorn Robert A.
Published: October 2005

A theory is developed to describe the propagation of sound waves in a rigid isotropic and homogeneous porous medium filled with a compressible fluid, including both the effect of viscous dissipation and the effect of thermal conduction. An expression for the conductance as a function of the frequency is derived by assuming a capillaric model. A comparison is made with independent experimental results, and close agreement with the theoretical results is obtained. A discussion of the structural parameters, including a description of a method for determining their values at a given frequency, is also made.
Laser Visualization of Ultrasonic Phase Gratings
Authors: Porreca Flavio
Published: October 2005

We report a very simple device for directly visualizing ultrasonic phase gratings, which can be used for very accurate measurements of ultrasonic velocity in liquids. The results are very good and useful for teaching purposes and scientific researches.
Dynamic Responses of Elastic Cylindrical Shells to a Concentrated Radial Load
Authors: Lu Y. P. , Wang Y. F.
Published: October 2005

An analysis is presented for obtaining the steady-state response of infinitely long elastic cylindrical shells subjected to a concentrated radial load. The effects of a small amount of internal material damping are included. The Fourier integral transform and series solution technique are employed for determining the solutions of the governing equations. Numerical results of a steel long shell to a concentrated radial load are presented.
Transmissibility of Repeated Impact
Authors: Thomson William T.
Published: October 2005

The problem examined is the steady-state response of a single-degree-of-freedom system subjected to repeated impact at equal intervals of time. Transmissibility curves for various damping, plotted as a function of the frequency ratio, are presented.
Maximum Available Sound-Pressure Levels from Stereo Components
Authors: Wood William S. , Lipscomb David M.
Published: October 2005

A commercially available tape recording of “rock” music was played through ten popular stereo receivers to drive, in turn, four stereo earphone sets. The sound generated by each system combination was analyzed into ten 5-dB bands. Results of the acoustic analysis indicated that all combinations of receiver earphones set for maximum output consistently exceeded established damage-risk criteria. It was concluded that popular stereo components can be potentially dangerous to the hearing mechanism if operated at or near maximum power output.
Reverberation Time Formulae Reconsidered
Authors: Yen Timothy Y.
Published: October 2005

The widely used reverberation time formula due to Eyring was derived on the assumption of step-wise drops in the energy level of a diffuse sound field. The argument, besides being difficult to follow, was not justified from the statistical notion of a diffuse field. It is found that Eyring's formula can be extracted from a difference equation based on an energy principle which preserves the continuous nature of the decay process. Interpretations of the average absorption coefficient are also given.
Discrimination of Temporal Gaps
Authors: Abel Sharon M.
Published: October 2005

This research investigates the human observer's ability to judge differences in duration without the benefit of such cues as differences in energy and energy spectrum. Three observers compared two silent durations, T and T+ΔT, in a two-alternative forced-choice procedure. The value of T ranged from 0.63 to 640 msec. For each T, seven values of ΔT were chosen to cover the range of the psychometric function. The duration and amplitude of noise markers bounding the temporal gaps were varied across three experimental conditions. For silent durations less than 160 msec, the results showed that discrimination depended on the parameters of the marker. For each marker condition, the function relating the Weber fraction and T was non-monotonic, reaching a local minimum at about 2.5 msec and a local maximum at 10 msec. These results were used to evaluate current theories about the central processing of duration.
Fractional Distortion Pairs in the Cochlea
Authors: Boston J. R. , Robbins Ruth G. , Dallos Peter
Published: October 2005

Experiments that were designed to investigate the properties of a peculiar type of distortion that has been observed in the cochlea at high excitation intensities are described. The pairs consist of two components with frequencies that are equally spaced about one-half the excitation frequency and that sum to the excitation frequency. Pairs centered on odd-harmonics of one-half the excitation frequency were also observed. The pairs exhibit a threshold of appearance, their frequencies can drift with time, and at excitation intensities well above threshold the pairs develop into noisy bands instead of remaining as discrete frequency components. Distortion pairs with similar properties were observed in five different species of the order Rodentia. An analogy between the behavior of the pairs with increasing excitation intensity and the development of turbulence in the boundary layer over a flat plate is discussed. The turbulence arises from an instability in the flow, and it is suggested that the cochlear distortion pairs develop from a similar instability in the cochlear flow.
Detectability of Interaural Time Differences and Interaural Level Differences as a Function of Signal Duration
Authors: McFadden Dennis , Sharpley Alan D.
Published: October 2005

Detectability was measured as a function of signal duration for a dichotic condition in which there was only an interaural difference in level and for one in which there was only an interaural difference in time. For four subjects, performance improved as duration increased, and it did so in essentially the same way for the two dichotic conditions; however, one other subject was unusual in that he showed little improvement in performance as duration was increased when the sole interaural cue was a time difference. Masker and signal: the same band of noise, 50 Hz wide centered at 500 Hz. Method: single-interval forced choice.
Recommended High-Frequency Audiometric Threshold Levels (8000–18 000 Hz)
Authors: Northern Jerry L. , Downs Marion P. , Rudmose Wayne , Glorig Aram , Fletcher John L.
Published: October 2005

The normal range of auditory sensitivity for pure-tone signals (8000 to 18 000 Hz) has been well bracketed in laboratory studies, generally with experienced listeners. This study reports results obtained during a field survey of high-frequency hearing conducted with 237 subjects at the 1968 Denver ASHA Convention. These results agree quite closely with data from the laboratory studies. The purposes of this study are threefold: (1) to report high-frequency field survey audiometric thresholds as a function of age and sex; (2) to review and compare results of all previous reports of high-frequency hearing threshold studies, with particular attention to differences in calibration techniques; and (3) to recommend the Zislis and Fletcher [J. Aud. Res. 6, 189–198 (1966)] threshold results obtained from sixth through 12th grade girls, with smoothing and minor modifications at 16 and 18 kHz, as the best representation of the “most sensitive hearing” for frequencies from 8000 to 18 000 Hz. It is recommended that these values be used as an interim standard until such time as official standard values are promulgated.
Audibility Region of Combination Tones
Authors: Smoorenburg Guido F.
Published: October 2005

This paper describes research on combination tones of the type f1 − k (f2 − f1. Such tones are audible during stimulation by the two frequency components f1 and f2, with f1 < f2. The results of the experiments suggest that these combination tones are audible only in a restricted frequency region below f1. The lower limit of this “audibility region,” for the combination tone 2f1 − f2 (k = 1), was determined primarily by the level of the lower stimulus component L1 and additionally by L2. The width of the audibility region appeared to be highly subject dependent. The lowest stimulus level for which 2f1 − f2 was audible was 15–20 dB SL if both stimulus components had equal levels. If the lower component was set at 40 dB, then the higher one could be reduced to 4 dB before 2f1 − f2 reached threshold. Higher-order combination tones could be perceived up to k = 5 or 6. At 40 dB SL, the lower limit of the audibility region was approximately the same regardless of the order (i.e., independent of k). The width of the audibility region could not be explained completely by the amount of interaction of the mechanical stimulation patterns corresponding to f1 and f2. In addition, it is demonstrated that these combination tones may play a misleading part in masking experiments. The detection threshold of a simple tone masked by another simple tone may be determined by the detection of a combination tone of the type f1 − k (f2 − f1), even at a low level of the masker.
Perception of Amplitude-Modulated Auditory Signals by the Goldfish
Authors: Fay Richard R.
Published: October 2005

The behavioral responses of goldfish to a variety of amplitude-modulated (AM) acoustic signals were studied using a stimulus generalization paradigm in combination with a classical conditioning method. Measurements were thus allowed of the equivalence among various complex and simple signals in controlling the conditioned respiration response. The goldfish's conditioned response to AM signals were found to be controlled by carrier frequency, modulation depth, and to a lesser extent, by modulation frequency in the 40-Hz range. On the other hand, pure-tone frequency exerted minimal behavioral control for subjects conditioned to AM signals. Subjects conditioned to a 40-Hz pure tone tended to generalize maximally to an AM signal having a 40-Hz modulation rate. The results indicate the degree to which the goldfish can use much of the information present in complex periodic acoustic signals and suggest the existence of periodicity pitch in fish.
Magnetically Coupled Stimulation of the Ossicular Chain: Measures in Kangaroo Rat and Man
Authors: Glorig Aram , Moushegian George , Bringewald Peter R. , Rupert Allen L. , Gerken George M.
Published: October 2005

A ferrite core coil is used to drive a small magnet fastened to the ossicular chain in kangaroo rat and man. The cochlear potentials recorded in kangaroo rat to such a drive are the same as when acoustic stimuli are used. When magnetic coupling is used to drive the human ossicular chain, the subject hears sounds that are indistinguishable from sounds generated through earphones.
Effects of High-Intensity Sound on Muffler Element Performance
Authors: Sacks M. P. , Allen D. L.
Published: October 2005

This paper presents the result of an experimental investigation designed to study the effect of high-intensity sound on muffler element performance. Five prototype mufflers were built and tested over a wide range of frequency and intensity. The mufflers were chosen as being representative of basic single-element and combination reactive mufflers. The apparatus consisted of an acoustic transmission line driven by an electromagnetic sound source and terminated anechiocally. Attenuation data are presented superimposed on curves derived from linear-acoustic theory. Conclusions are stated for expansion chamber mufflers at higher sound pressure levels (SPLs) than could be produced by the test equipment by using constriction tube data and acoustic similarity between these elements. It is shown that the expansion chamber muffler will operate as a linear element when subject to incident SPLs of 165–180 dB depending on muffler attenuation. Mufflers containing resonator elements show no deviation from a linear theory when subject to SPLs of the order of 160 dB except at points near a resonant frequency
Two-Dimensional Probability Structure of Wind-Driven Waves
Authors: Spindel R. C. , Schultheiss P. M.
Published: October 2005

Measurements of the two-dimensional waveheight probability distribution of wind-driven waves in a model tank suggest that the use of bivariate Gaussian statistics in acoustic scattering computational approximations may be much less realistic than assuming Gaussian behavior in only one dimension.
Atmospheric Absorption of Sound: Analytical Expressions
Authors: Bass H. E. , Bauer H.-J. , Evans L. B.
Published: October 2005

A set of analytical expressions has been developed which will predict the absorption of sound in air at 20°C. The results agree within 3% of previous work in the frequency range of 100 Hz 1 MHz for all humidities. Below 100 Hz accuracy cannot be judged because of lack of knowledge about the vibration-vibration energy transfer between CO2 and O2.
Scattering of Acoustical Waves by a Prolate Spheroidal Obstacle
Authors: Sidman Robert D.
Published: October 2005

A rigid prolate spheroidal obstacle that is part of a mass-spring-dashpot system in an acoustical medium is struck by a plane pressure wave and also by a spherical pressure wave. ZP* (k) and ZS* (k) are the Fourier transforms of the motion of the spheroid in the plane-wave case and spherical-wave case, respectively, and f* (k) and g* (k) are the respective transforms of the incident pressures in these cases. The equation relating ZP* (k) and f* (k) and the equation relating ZS* (k) and g* (k) are derived. The asymptotic forms for the acoustical admittances ZP* (k)/f* (k) and ZS* (k)/g* (k) are computed for k small and from these results the condition that f and g must satisfy in order that ZP (t)∼ZS (t) for t large is derived. Finally the distance c between the foci of the spheroid is allowed to approach 0, yielding the preceding results in the case of a spherical obstacle.
Influence of a Surface Mass Distribution on the Motion of Bars
Authors: Torvik Peter J. , Wade James E.
Published: October 2005

A method is developed for determining the modes of propagation for progressive harmonic waves in infinite rectangular elastic bars. The faces of the bar are covered with a distributed mass of negligible stiffness, as found with a layer of insulation or a damping treatment. An approximate solution is obtained by expanding the displacements as a power series in the thickness coordinates and retaining only terms through first order. The D'Alembert force due to the acceleration of the mass produces surface tractions which influence the motion and introduce coupling between the longitudinal, torsional, and flexural motions. If equal mass distributions are applied over opposite faces, the motions are qualitatively similar to the motions of a free bar. If unequal masses are added to opposite faces, the motions are more coupled than those of a free bar. The addition of mass to two adjacent faces leads to a yet higher degree of coupling.
Expansion and Contraction of Planar, Cylindrical, and Spherical Underwater Gas Bubbles
Authors: Epstein David , Keller Joseph B.
Published: October 2005

The one-dimensional motion of a planar gas bubble, the axially symmetric motion of a cylindrical bubble, and the spherically symmetric motion of a spherical bubble in a liquid are considered. Following J. B. Keller and I. I. Kolodner [J. Appl. Phys. 27, 1152–1161 (1956)], the velocity potential in the liquid is assumed to satisfy the wave equation, while the pressure is assumed to be uniform throughout the bubble. In each case there is an equilibrium bubble radius ā. First the small-amplitude motions about equilibrium are found. In the planar case the bubble radius a (t) tends monotonically to ā; in the cylindrical case a (t) performs a finite number of damped oscillations and then tends monotonically to ā; and in the spherical case a (t) tends in an oscillatory way to ā. Next, large-amplitude motions are treated. In the planar case they are determined analytically and it is found that a (t) still tends monotonically to ā. In the spherical case an ordinary differential equation is derived for a (t) which has been solved numerically by Keller and Kolodner (op. cit.), and which yields damped oscillations. In the cylindrical case a pair of nonlinear integrodifferential equations is derived for a (t) and for the velocity potential. These equations are solved numerically and yield a finite number of oscillations followed by a monotonic approach to equilibrium, in agreement with the small-amplitude theory.
Infrasound in the Ionosphere Generated by Severe Thunderstorms
Authors: Davies K. , Jones J. E.
Published: October 2005

Radio observations of ionospheric perturbations have revealed an association between severe thunderstorms and infrasonic pressure waves that propagate through the F region at heights of 200 to 400 km. These waves are characterized by periods of 3.5 and 4.5 min. An acoustic ray-tracing method is described, which is used to locate the sources of the infrasonic waves.
Bandpass Noise Stimulation of the Simulated Basilar Membrane
Authors: Glaser Edmund M. , Haven Miles
Published: October 2005

The envelope of the rms deflection of the basilar membrane has been studied by means of a digital computer model simulation. The deflection envelope was observed for equal-intensity bandlimited noise stimuli centered at a frequency of 300 Hz. Two kinds of noise-band symmetry were used: arithmetic and geometric. Bandwidth was varied in steps from pure tone to 4 oct. It was found that as the bandwidth of the noise increased, the length of the membrane that exceeded an arbitrary threshold increased quite slowly until a bandwidth of about 100 Hz was reached. The threshold used was 0.5 of the maximum deflection to pure tone. At higher bandwidths, suprathreshold membrane length increased more markedly. When a higher threshold near that of the pure-tone maximum deflection was employed, the suprathreshold membrane length decreased then increased with bandwidth. Comparison of these results with psychoacoustic studies on loudness and the critical band reveal similarities. They suggest that loudness phenomena may originate peripherally and be associated closely with the extent of the basilar membrane simulated.
Masking by Combination Bands: Estimation of the Levels of the Combination Bands (n + 1)fl − nfh
Authors: Greenwood Donald D.
Published: October 2005

In a previous paper (Greenwood, 1972a), the measurement of masking by bands of noise of external origin led to determinations of signal/masker ratio that are applied in the present paper to the task of estimating combination band levels. Estimates of the levels of combination bands, given by the expression (n + 1)fl − nfh, were made by using the maximum masked threshold, read from a masking pattern produced by a given band, to calculate the denominator of the previously obtained signal-to-masker ratio. The shapes of the masking patterns and the estimates of level lead to the following conclusions: (a) Comparison of the masking effects of combination bands and bands of external origin further demonstrates that to assume that combination components, once generated, are not equivalent to external stimuli in ultimate loci and subsequent effects in the cochlea would require complex ad hoc explanations to account for the indistinguishable masking effects produced by the two kinds of bands. (b) Combination bands generated by mixtures of line and continuous spectra vary in level as functions of stimulus parameters in ways very similar to the variation in the level of combination tones produced by tonal primaries, as measured by cancellation techniques (Zwicker, 1955, 1968; Goldstein, 1967). (c) The present data extend the previously reported empirical functional relations, in that the level of the band 2fl>−fh is (i) a less sensitive function of primary frequency separation at higher primary levels and (ii) a more nearly constant percentage of primary level at wider primary separations. (d) The generation of combination components in essentially the same way, whether they are produced by line, continuous, or mixed spectra, should advance the task of calculating empirically the amplitude characteristics of the combination spectra produced by complex primary spectra.
Differences of Interaural Phase and Level in Detection and Lateralization: 1000 and 2000 Hz
Authors: McFadden Dennis , Jeffress Lloyd A. , Lakey John R.
Published: October 2005

Detection and lateralization performance were measured using as a signal the same narrow band of noise that served as the masker. The center frequency of the noise band was either 1000 or 2000 Hz, in different experiments. Both diotic (N0-S0) and dichotic (N0-Sπ) data were taken at both frequencies. By varying the signal-to-masker ratio and the angle α at which the signal is added to the masker in the N0-Sπ condition, it is possible to control the magnitudes of the two binaural cues—interaural time difference and interaural level difference. The outcomes at 1000 Hz support our previous findings—subjects differ in their sensitivities to the two cues, and the cues do not cancel perfectly when the task is detection. At 2000 Hz, even relatively large interaural time differences were of little or no benefit either for detection or lateralization, and interaural level difference was the primary binaural cue. At 1000 Hz, sizeable masking-level differences (MLDs) were observed for all subjects at all values of α. At 2000 Hz, the MLDs were large at α = 0°; however, detectability was essentially the same in the conditions N0-Sπ, α = 90°, and N0-S0, α = 90° implying that in both of these conditions performance was based on the increment in level that occurred with signal onset.
Physiological Noise as a Masker of Low Frequencies: The Cardiac Cycle
Authors: Soderquist David R. , Lindsey John W.
Published: October 2005

This study quantified the effects of a physiological masker, the heartbeat, on the detectability of a low-frequency tone (100 Hz, 100-msec duration). Using a YES-NO signal detection paradigm, binaural sensitivity (d′) was examined as a function of the temporal location of the signal onset within the cardiac cycle. The independent variable was the temporal delay in signal onset following the subject's own EKG R wave. Signal delays were selected (0.0 to 0.8 sec in 0.1-sec steps) and presented to four subjects. Results reveal depressed sensitivity with signal delays of 0.0, 0.3, and 0.7 sec following the EKG R wave. In contrast, maximum sensitivity occurred near 0.5 sec following the R wave. The results were discussed in terms of physiological masking produced by valve closures within the heart.
Emotions and Speech: Some Acoustical Correlates
Authors: Williams Carl E. , Stevens Kenneth N.
Published: October 2005

This paper describes some further attempts to identify and measure those parameters in the speech signal that reflect the emotional state of a speaker. High-quality recordings were obtained of professional “method” actors reading the dialogue of a short scenario specifically written to contain various emotional situations. Excerpted portions of the recordings were subjected to both quantitative and qualitative analyses. A comparison was also made of recordings from a real-life situation, in which the emotions of a speaker were clearly defined, with recordings from an actor who simulated the same situation. Anger, fear, and sorrow situations tended to produce characteristic differences in contour of fundamental frequency, average speech spectrum, temporal characteristics, precision of articulation, and waveform regularity of successive glottal pulses. Attributes for a given emotional situation were not always consistent from one speaker to another.
Propagation of Elastic Waves in a Cylindrical Bar Subject to a Moving Load on Its Lateral Surface
Authors: Baum Dennis W. , Smith Wesley R.
Published: October 2005

The results of a theoretical and experimental study of the elastic strain produced in a cylindrical bar by a moving step function load on the lateral surface are presented. A double transform technique is used to solve the problem of determining the elastic strain produced by both normal stress loading and shear stress loading on the lateral surface of the bar. The exact solution is given as a sum of Fourier integrals, all but one of which are identified as Pochhammer-Chree waves. The additional Fourier integral represents a mode of elastic wave propagation which is nondispersive and has a phase velocity equal to the lateral surface loading velocity. Asymptotic solutions to the Fourier integrals are obtained and compared with experimental strain-time records. When corrections are included for electrical circuit response and viscoelastic effects, the predicted strain-time curves fall within the experimental error associated with the records. Strains were measured using thin film strain gauges embedded in a plexiglas bar. The bar was loaded by a plane air shock.
Experimental Measurements of the Scattering of Acoustic Waves by Rough Surfaces
Authors: Welton P. J. , Frey H. G. , Moore P.
Published: October 2005

Measured scattering coefficients are presented for four randomly rough, pressure-release surfaces which are statistically related. The scattering data were collected at frequencies of 100, 200, and 500 kHz for forward, specular, and backscattering geometries. The ratios of acoustic wavelength to surface rms height (λ/h) range from 0.33 to 6.5. The most obvious features of the data are the increasing diffuseness of the scattered energy with increasing roughness, and the substantially frequency independent behavior of the scattering coefficients.
Sonic Booms in the Sea: A Recent Observation
Authors: Urick R. J. , Tulko T. J.
Published: October 2005

Sonic booms from a low-altitude supersonic aricraft in level flight over a calm sea have been recorded. At a depth of 100 ft, the underwater boom has been found to be a weak irregular blob comparable in level with the jet noise of the aircraft, without the doublet character of the sonic boom in air.
Polarization of Electret Microphones with Energetic Electrons
Authors: Brown R. , Rester D. H.
Published: October 2005

The polarization of assembled electret microphones with energetic electrons from a Cockcroft-Walton accelerator is discussed. Electron transmission curves of metallic foils and of the dielectric films Mylar and FEP Teflon are given based on experimental measurements. Results of charging experiments on Mylar and FEP are presented which show how the optimum electron bombarding energy and beam intensity were chosen for polarization of a given microphone. The method devised to monitor microphone performance in vacuum while polarization is carried out is described. The polarization of a specific microphone is discussed to illustrate the use of the electron transmission data and the method of monitoring the microphone performance.
New Boundary Conditions and Results for the Peterson-Bogert Model of the Cochlea
Authors: Geisler C. Daniel , Hubbard Allyn E.
Published: October 2005

The Peterson-Bogert model of the cochlea [J. Acoust. Soc. Amer. 22, 369–381 (1950)] specifies, as one of its boundary conditions, zero pressure at the round window. This specification is equivalent to eliminating the round-window membrane. We have substituted a new boundary condition, representing the round-window membrane with an acoustic stiffness. With the new boundary condition, the equation for p+(x) requires a new solution, and a new value of p− (x) at x = 0 is needed. The solution for p+ (x) and the necessary value of p− (0) are given as a function of frequency for sinusoidal stimulation. The latter value is used as the input to the Peterson-Bogert type of model of the basilar membrane. The model's input impedance as well as the relative displacement between the oval and round windows are also given. These relationships are compared with experimental findings.
Modeling and Simulation of the Cochlear Potentials of the Guinea Pig
Authors: Laszlo C. A. , Milsum J. H. , Gannon R. P.
Published: October 2005

A combination of mathematical modeling techniques and computer simulation methods has been used for the interpretation of the behavior of the experimentally observed cochlear potentials. In particular, the models of the mechano-acoustical system and of the electrical potential generating mechanism of the transducer cells have been derived in terms of state variables and of equivalent functional relationships, respectively. These formulations allow economical numerical solution of the complex equations which describe cochlear functions. Using these techniques we have been able to confirm that nonlinearity of the individual haircell output is compatible with the observed apparent linearity of the experimentally observed macroscopic CM (cochlear microphonic) potential and that effective low-pass filtering reduces distortion in the measured potential waveform due to the interaction of the electrical outputs of the haircells along the basilar membrane. This filtering is not influenced to a great extent by the attenuation along the cochlea. Further filtering may also be contributed by the RC networks formed by the various membrane capacitances and resistances. Comparison of the experimental and simulated CM vs SPL functions (frequency as parameter) shows that a simple phase cancellation process is not sufficient, but that an additional mechanism must be postulated to account for the decrease of the CM at very high sound intensities; the IHC (internal haircell) output is assumed to be 20 dB less sensitive than the OHC (outer haircell) output and of opposite sign. A similar comparison for the CM amplitude, CM phase, and SP− amplitude as functions of frequency (SPL as parameter) also provides good agreement. Our results demonstrate that the particular behavior of the basilar membrane and the interference effect between haircell outputs account for the majority of electrical phenomena observed by the classical differential electrode method.
The Critical Masking Interval
Authors: Penner M. J. , Robinson Charles E. , Green David M.
Published: October 2005

We investigated the concept of a critical masking interval, the time period during which noise is effective in masking a brief signal. The signal was a 100-μsec click temporally placed in the center of a gated-noise masker. Both the click and the noise were low-pass filtered so that the power spectra of signal and noise have similar shape. The duration of the noise masker was varied from 100 μsec to 300 msec and two noise levels were employed. Like the estimate of the critical bandwidth, the estimate of the critical masking interval can be made in two independent ways. First, for long durations of the noise masker, the ratio of click energy to overall noise power indicates that the critical masking interval is about 14 msec. Second, progressively shortening the duration of the noise masker did not improve detectability until the duration was less than approximately 10 msec. The near agreement of these two independent estimates supports our interpretation of the data in terms of the concept of a critical masking interval.
Shear as a Mechanism for Sonically Induced Biological Effects
Authors: Rooney James A.
Published: October 2005

By controlled irradiation of erythrocyte suspensions at 20 kHz it is demonstrated that shear associated with acoustic microstreaming can be an important mechanism for biological effects of sound. Two effective sources of acoustic microstreaming are stable oscillating gas bubbles and transversely oscillating wires. The threshold displacement amplitude for achieving critical shear can be reduced by increasing the solvent viscosity and reducing the radius of the source of acoustic streaming. The threshold stress was found to decrease by 55% or more when the sample was heated to 45°C or higher for 10 min. This suggests that synergism exists between mechanical and thermal mechanisms for sonic effects. Mass transfer associated with small-scale acoustic streaming controls the rate of cell disruption.
Numerical approach to the determination of the performance of acoustic lenses
Authors: Jones H. W.
Published: October 2005

An attempt has been made to evaluate the performance of the simplest type of liquid-solid lens, i.e., a hemispherical surface between the liquid and solid. The nature of the image allowing for the effects of refraction, absorption, and mode conversion has been determined for an equally spaced object and image. It appears that the diffraction effects are the only important ones and that geometric aberration is unimportant.
Perception of dichotically presented vowels
Authors: Weiss Michael S. , House Arthur S.
Published: October 2005

Listeners heard vowels in syllabic contexts, presented dichotically at S/N (signal-to-noise) ratios of 0 and −10 dB, and their responses were analyzed in terms of individual ears. In the most-adverse listening condition the level of correct response in the right ear was 6% higher, on the average, than that obtained in the left ear; there was no difference between ears in the more-favorable listening condition.
Effect of diffusion on the growth and decay of acceleration waves in gases
Authors: Bowen Ray M. , Doria Michael L.
Published: October 2005

As is well known, a small compressive disturbance in an elastic gas grows into a shock wave in finite time. If the gas is viscoelastic or has internal degrees of freedom, this result is no longer true unless the initial amplitude of the disturbance is larger than a critical amplitude. This article investigates the effect of diffusion on the growth and decay properties of small disturbances in a mixture of elastic gases. It is shown that a critical amplitude exists for the mixture. Thus, diffusion can be thought of as having a stabilizing effect in that not all compressive disturbances will grow into shock waves.
Perceptual confusions between four-dimensional sounds
Authors: Webster John C. , Woodhead Muriel M. , Carpenter Alan
Published: October 2005

The aim of this study was to determine the relative importance of source parameters (fundamental frequency and waveform) versus formant parameters (resonant frequency and number) in identifying meaningless complex sounds. Sixteen sounds were generated differing on four dimensions, each having two values. These were the source waveform, containing either all harmonics or odd harmonics only; the fundamental frequency, either 90 or 142 Hz, ratio=1.6; the number of formants, one or two; and the frequency of the formant(s) either low (600 Hz, or 600 and 1550 Hz) or high (940 Hz, or 940 and 2440 Hz) high/low ratio = 1.6. Twenty-four listeners were trained to identify these sounds. The results show that fewer confusions were made between pairs of sounds (1) as the number of dimensions on which they differed increased, and (2) as the dimension (single or in combination) changed, from formant number to formant frequency region, to fundamental frequency, to source waveform. Listeners appear to make a generalized classification along a single dimension which seems to vary systematically with waveform complexity and periodicity.
The wolf in the cello
Authors: Firth Ian M. , Buchanan J. Michael
Published: October 2005

The occurrence of the wolfnote in the cello is shown by direct tonal analysis to be caused by the beating of two equally forced oscillations. The fundamental sinusoidal component of vibration of the string is shown to split at the wolfnote into a pair of oscillations separated by a frequency interval equal to that of the stuttering frequency of the wolfnote. In one of the two cellos investigated, higher partials up to the third are also split into pairs, their separation being the multiple of the harmonic number and the separation of the fundamental pair. Further evidence is obtained to support the interpretation of the wolf as beating between two equal forced vibrations from a frequency analysis of the bowed-string vibration for different stopped string lengths. The frequencies of vibration of the string bear a close resemblance to those obtained in coupled electrical resonant circuits.
Optical probing of ultrasonic diffraction in single crystal sodium chloride
Authors: Liu John Moyu , Green Robert E.
Published: October 2005

Results are presented of an experimental study of ultrasonic wave diffraction for the acoustical modes propagating along the [1̄1̄2], [11̄0], and [111] directions in single crystal sodium chloride. Laser beam optical probing in the Raman-Nath regime was used to map the sound intensity distribution in the farfield of circular transducers. Calculations of the diffraction spread based on representation of the acoustic field by an angular spectrum of plane waves are in agreement with the experimental measurements. A simple method for estimating the diffraction spread based on the geometry of the inverse speed (slowness) surfaces is presented.
Integral equation formulation of dynamic acoustic fluid-elastic solid interaction problems
Authors: Shaw R. P.
Published: October 2005

The interaction of waves traveling in an acoustic medium with an elastic obstacle (or vice versa) is studied by a formulation which has been useful in previous acoustic and elastic wave scattering problems. This formulation is based on an integral equation representation of wave problems and has the advantage of involving only boundary (i.e., interface) values of the unknowns, thus reducing the dimensionality of the problem. A simple example of plane wave scattering is included as an illustration for both time harmonic and transient cases as well as a spherical radiation problem to indicate the use of the procedure in a curvilinear geometry. Emphasis is on the method of approach and no new results are obtained.
Geometrical theory for flexure waves in shells
Authors: Germogenova O. A.
Published: October 2005

The paper presents a formulation of geometrical theory for transverse flexure waves propagating in thin shells. The dynamic equations correspond to the states of vibration with large values of the index of variation (Bolotin). The basic equations of geometrical optics (the eikonal equation, the Fresnel equation, and the energy conservation law) are obtained for shells with arbitrary (smooth) metrics. Their applications are illustrated with the examples of sphere and ellipsoid of rotation.
Noise radiated from a turbulent boundary layer
Authors: Vecchio E. A. , Wiley C. A.
Published: October 2005

The theory for the fluid-dynamic generation of sound, recently developed by Lotsch for boundary-layer turbulence, is extended by making use of correlations. Its application to the experimental configurations used by Haddle and Skudrzyk showed good agreement between theory and experiment for the radiation-field pressures produced by an aluminum and a wooden buoyant vehicle.
Computer simulation of the nearfield for elastic wave in a solid half-space
Authors: Harumi Kasaburo , Suzuki Fukuzo , Satô Yasuo
Published: October 2005

The equations for elastic waves are solved by the finite-difference approximation and the distributions of displacement and stress at the nearfield in an elastic half-space are calculated for a simple harmonic strip source with a finite width on the surface of the medium. The stress distribution at the nearfield in a solid, calculated here, will give useful data for ultrasonic testing, showing different features of the field from those in a liquid. The particle orbits near the source are also obtained, and they show irregularities caused by the coupling of body and surface waves. In this way the computer simulation reveals the wave property in a solid, for example, the existence of the surface wave region, and also the existence of the shear region in which the displacements show the periodicity of the wavelength of shear wave.
Nonlinear transverse vibrations of beams with properties that vary along the length
Authors: Nayfeh Ali Hasan
Published: October 2005

The method of multiple scales is used to analyze the nonlinear transverse vibrations of inhomogeneous beams including the effects of transverse shear and rotary inertia. First-order uniform perturbation expansions are derived for the displacements, shear force, and frequency in terms of the ratios of maximum transverse displacement to cross-sectional radius of gyration and cross-sectional radius of gyration to wave length.
Ultrasonic attenuation by spectrum analysis of pulses in buffer rods: Method and diffraction corrections
Authors: Papadakis E. P. , Fowler K. A. , Lynnworth L. C.
Published: October 2005

A method is presented for measuring ultrasonic attenuation as a function of frequency by spectrum analysis of broad-band echoes in a buffer/specimen system. Also presented is a new technique for diffraction corrections in this configuration. The buffer rod/spectrum analysis method with diffraction corrections is applied to three experiments to demonstrate its accuracy and versatility in measuring attenuation and defining transducer radiation/reception efficiency.
Ultrasonic attenuation as function of temperature in a 1% carbon steel
Authors: Tripathi R. C. , Verma G. S.
Published: October 2005

The “Shouldered-specimen pulse echo technique” has been used to study the temperature dependence of ultrasonic attenuation α at 5 MHz, in a 1% carbon steel. The attenuation-versus-temperature curve shows abrupt changes in its slope at 750 ° and 900 °C, respectively, after which the attenuation rises rapidly for temperatures up to 985 °C. A qualitative explanation of the experimental curve is sought on the basis of Bhatia's theory of scattering by the grains. The present work is first of its kind to provide evidence for the growth of the austenitic grains with increasing values of temperature in the austenitic range.
Analysis and measurement of ultrasound backscattering from an ensemble of scatterers excited by sine-wave bursts
Authors: Sigelmann Rubens A. , Reid John M.
Published: October 2005

This paper develops a practical approximation for the backscattering of periodic bursts of sine waves by a volume of randomly distributed scatterers. The approximation is applied to the measurement of a “volumetric backscattering cross section,” using a substitution method in which the rms value of the gated backscattered signal is compared with the rms value of a wave reflected from a target of known coefficient of reflection. It is shown that the signal backscattered from the ensemble depends on the attenuation of the wave in the volume and upon the burst and gate lengths. An equation to obtain the volumetric backscattering cross section from experimental data is derived.
Flexural vibrations of clamped orthotropic plates
Authors: Bauer Louis , Reiss Edward L.
Published: October 2005

Perturbation and numerical methods are used to obtain approximations of the natural frequencies and modes. The results suggest that the perturbation method gives an accurate estimate of the principal frequency even for “strongly orthotropic” plates. The solution of the clamped isotropic plate problem for the same shape plate is the leading term in the perturbation expansion.
Comparison of experimental and theoretical responses in hollow rods to a transient input
Authors: Pernica G. , McNiven H. D.
Published: October 2005

Transient wave propagation in an isotropically elastic, hollow rod is studied experimentally to help appraise existing and new rod analyses. The study involves a comparison between the actual dynamic response of a hollow rod determined from experiments and the response of the same rod as predicted using the method of characteristics and an approximate theory. Not only is the method itself appraised but insight (though limited by experimental data) is gained into what order approximate theory is appropriate for a rod of a particular cross-sectional geometry. Two approximate theories are presented: a membrane theory which is already in existence and a two-mode theory which is new. The governing equations of motion for this latter theory are derived and the frequency equation is established. The experimental results are due to Heimann and Kolsky and are in the form of responses, at two stations, to an impact on the end of the rod. Comparison with theory is obtained by treating the response at the first arrival station as an input. By this device, an input is formulated in which the actual, complicated dependency on time is known at the expense of the radial dependency. The trade is based on the belief that for hollow rods, except perhaps when the walls are thick, an assumed distribution of strains through the thickness that is consistent with the boundary conditions and the kinematics of the approximate theory will differ little from the actual strains. The responses from experiment and theory at the second station are remarkably close to one another, which would seem to establish the value of the method of characteristics for the type of problem considered here.
Tables of the speed of sound in open ocean water (with Mediterranean Sea and Red Sea applicability)
Authors: Del Grosso V. A.
Published: October 2005

Simple tables requiring at most a linear interpolation and addition are presented for the speed of sound in the open ocean. These tables cover the range 30–42 0/00 S, −2°–32° C, and 0–1100 kg/cm2 gauge, so they have some applicability also to the Mediterranean and Red Sea. The tables were produced from an equation having a standard deviation of 0.05 m/sec which fit at NUC to the latest NRL measurements.
Localization of high- and low-frequency transients
Authors: Banks Martin S. , Green David M.
Published: October 2005

Subject's ability to localize transient signals presented in a free field depends primarily on low-frequency energy. The minimum audible angle is about 3/4° for all transients containing energy below 2000 Hz.
Perstimulatory loudness adaptation
Authors: Bray David A. , Dirks Donald D. , Morgan Donald E.
Published: October 2005

An experiment is described in which perstimulatory loudness adaptation was measured under heterophonic conditions using simultaneous dichotic loudness balance procedures on normal listeners. The adapting signals were 500 and 3000 Hz presented at 70 dB SPL for 12 min, the last 5 min of which involved perstimulatory loudness balances. A tracking technique and the method of constant stimuli were employed. The results indicated that continuous stimulation did not significantly decrease the loudness of the adapting signal. Thus, under test conditions that reduce or eliminate binaural interaction, suprathreshold loudness adaptation is essentially absent for pure-tone signals of 500 and 3000 Hz at 70 dB SPL.