bluuebunny/crossref_metadata_2025 huggingface dataset:
Cavitation dynamics: II. Free pulsations and models for cavitation bubbles
Authors: Flynn H. G.
Published: October 2005

A mathematical formalism developed for investigating the dynamics of cavitation bubbles has been used to obtain numerical solutions describing the behavior of bubbles of different initial radii that are damped by heat conduction, viscosity, and compressibility. Calculations have been made to determine two measures of damping, the maximum temperatures, the maximum pressures, and the resonance frequencies of bubbles set into pulsations by a pressure pulse. In general, these quantities are controlled by heat conduction and viscosity at small amplitudes and mainly by compressibility at large amplitudes of motion. One measure of damping—the energy dissipation modulus—has a peak at a well-defined maximum radius. This peak serves to define a transition radius; for pulsations with amplitudes greater than this transition radius, the fraction of available energy dissipated in a cycle decreases and hence very large internal energy densities may occur. A second transition occurs at a radius called the critical radius; for pulsations with amplitudes greater than this critical radius, inertial forces control the collapse of a bubble and very large kinetic energy densities may occur in the liquid at the interface. The transition radius and the critical radius, which are functions of the initial size of a cavity, have been used to define a dynamical threshold for cavitation. In a motion where the maximum radius exceeds this proposed threshold, the characteristic phenomena of cavitation may be expected to appear. The dynamical threshold has in turn been used as the basis for models of cavitation bubbles useful in interpreting such phenomena.

Subject Classification: 30.70, 30.60.
Parabolic approximations for underwater sound propagation
Authors: McDaniel Suzanne T.
Published: October 2005

Several alternative parabolic approximations to the reduced wave equation and their numerical solution are investigated for underwater acoustics applications. Parabolic approximations are derived by splitting the wave equation into transmitted and reflected components. An exact splitting operator is found, and further parabolic approximations for the transmitted fields are based on approximations to this operator. For the case of a range-independent environment, the resulting parabolic approximations are compared with normal-mode theory. The efficiency with which numerical results can be obtained is discussed, and an example of propagation from shallow to deep water is given.

Subject Classification: 30.20; 20.15, 20.40.
Elastodynamic stress intensity factors for a crack in a layered composite
Authors: Keer L. M. , Luong W. C. , Achenbach J. D.
Published: October 2005

Elastodynamic stress intensity factors are computed for diffraction of antiplane shear waves by a crack in a layered composite. The crack is parallel to the layering. The problem is formulated by means of integral transforms, and reduced to the solution of a singular integral equation. The special case when the direction of the wave motion is perpendicular to the layering is studied numerically, and stress intensity factors are obtained for several values of frequency, material constants, and geometrical parameters.

Subject Classification: 40.55; 20.30.
Comparisons of variability in aircraft flyover noise measurements
Authors: Bishop Dwight E.
Published: October 2005

Data from controlled flight testing conducted for 11 aircraft noise certification programs under FAA FAR 36 show typical standard deviations for sets of EPNL and PNL values ranging from 0.8 to 1.4 dB. Much greater variability was found in the noise levels measured near the approach path to runway 21R at Detroit Metropolitan Airport during two ten-day periods of routine operations. EPNL, SEL, and maximum A-level data, classified in jet aircraft groups by number of engines (regardless of type), showed typical standard deviations ranging from 3.8 to 4.9 dB at the different ground measuring points. Correlation of the Detroit noise data with slant distance gave moderately high correlation coefficients, with 95% prediction intervals about the regression lines varying from ±5.4 to ±9.5 dB. The regression lines show quite good agreement, particularly in slope, with generalized noise level versus distance curves often used for noise exposure calculations. Correlations between different noise measures were high, as expected. However, prediction intervals about the regression lines were sizable, indicating distinct possibilities for occasional sizable errors in estimating one noise measure from another when analyzing aircraft flyover noise signals.

Subject Classification: 50.50, 50.55.
Noise and sleep: A literature review and a proposed criterion for assessing effect
Authors: Lukas Jerome S.
Published: October 2005

A brief discussion of human sleep is followed by presentation of data describing the variables that appear to affect human responsiveness to noise during sleep. Results from several studies that were conducted in different laboratories and that used several types of noises, age groups, and sexes are then combined to show that when EPNdB units are used as the measure of noise intensity, the correlation coefficient between intensity and the probability of no disturbance of sleep is −0.86. It is suggested also that a coefficient of similar magnitude would be obtained if units of EdBA were used. Some implications of these data are then exemplified.

Subject Classification: 50.70, 50.75.
Clustering of volume reverberation spectra: An application of correspondence analysis
Authors: McElroy Paul T. , Smith Woollcott
Published: October 2005

Correspondence analysis has been applied to 34 spectral curves of volume reverberation to cluster the spectra into groups. The clustering is compared with an earlier grouping of the spectra based on the cross-standard-deviation matrix with essentially similar results. However, the correspondence analysis technique has a number of clear-cut advantages: (1) the clustering is quickly displayed in a two-dimensional plot; (2) eigenvectors computed in the analysis are spectral curves which are characteristic of extremum environments in the data set (we call them volume reverberation environments and discuss their possible indentification with preponderant fish species); (3) those frequencies which most directly serve as indicators of a particular cluster of spectra are identified; and (4) the examination of the relationship of environmental parameters and the factor scores computed in the analysis provide a basis for extrapolation of the spectra to their appearance in unmeasured conditions. The volume reverberation spectra (known as column strengths) are chosen as a particular example of the application of correspondence analysis; we believe it is broadly applicable to the problem of identifying and classifying spectra in many disciplines. As an aid to the reader in understanding the technique, we have summarized the governing equations of correspondence analysis and given a geometrical interpretation relating the original spectra, eigenvectors, and factor scores.

Subject Classification: 60.20; 30.40.
Time-frequency resolution experiment in speech analysis and synthesis
Authors: Patisaul C. R. , Hammett J. C.
Published: October 2005

This paper reports the results of a study of the perceptual consequences of the time and frequency resolution loss inherent in vocoded speech, and an evaluation of an adaptive resolution scheme. A cepstrum vocoder which adapted its time and frequency resolution according to the voiced–unvoiced nature of the input speech was computer simulated. Speech processed by the vocoder was subjectively evaluated and several tentative conclusions regarding time-frequency resolution and speech quality were drawn. The results of the study suggest that (1) 20-msec time resolution is adequate for vocoder applications, (2) adapting to better time resolution in unvoiced regions and regions of voiced–unvoiced and unvoiced–voiced transitions leads to improved speech quality in systems that do not normally maintain 20 msec or better time resolution, (3) frequency resolution may be reduced considerably in unvoiced and transition regions with no noticeable degradation in speech quality, and (4) time-frequency resolution trading may occur in the speech perception process.

Subject Classification: 70.40, 70.55, 70.50.
Comments on ’’Ambient noise level above plane with continuous distribution of random sources’’ [L. C. Sutherland, J. Acoust. Soc. Am. 57, 1540–1542 (1975)]
Authors: Garrelick Joel M. , Kleinschmidt Klaus
Published: October 2005

Data on the vertical gradient of noise levels outside high-rise buildings in urban areas are furnished and interpreted in terms of a hypothesis presented in Sutherland’s paper.

Subject Classification: 50.50; 28.45; 50.75.
Calculation of reverberation and average intensity of broad-band acoustic signals in the ocean by means of the RAIBAC computer model
Authors: Bachmann Wolfgang , de Raigniac Bernard
Published: October 2005

Based on the conventional ray-tracing principle, a fast numerical algorithm is developed that calculates averaged propagation loss and reverberation of underwater sound. The averaging is performed by summing incoherently the contributions of individual ray bundles to each of the rectangular cells into which the range/depth plane is divided. The resulting matrix description of the average intensity field is used to calculate reverberation. The propagation-loss algorithm is preliminarily tested against mathematical test functions and measured data.

Subject Classification: [43]30.20, [43]30.40; [43]85.84.
Expansion of a high-pressure gas sphere in a porous medium II: Fluid compressible
Authors: Epstein David
Published: October 2005

The work presented in an earlier paper [D. Epstein, J. Geophyos. Res. 72, 3701–3710 (1967)] on the expansion of a high-pressure gas bubble in a fluid-saturated porous medium, with the fluid treated as incompressible, is extended by treating the fluid as slightly compressible. Two limiting cases are considered: If the particulate matter is carried along with the fluid, the porous medium acts as a dense liquid, with parameters determined by simple functions of the density and compressibility of the fluid and solid particles, and the usual equations of motion apply. However, if the relative velocity of the fluid with respect to the solid is essentially equal to the fluid velocity, the motion is assumed to be governed by a compressible, generalized Darcy equation. From this equation a pair of integrodifferential equations for the bubble radius as a function of time are derived. The form of the radius-time curve depends on a nondimensional resistance factor m? = (1/2) β?/c, a combination of quantities characteristic of the fluid, the porous medium, and the gas bubble. The transition regime between ideal and Darcy flow is determined as a function of this parameter. For very small values, the bubble pulsates about the equilibrium raius ?. With increasing m?, the ratio of radiated acoustic energy to energy dissipated decreases, until the Darcy limit is reached, where bubble pulsation no longer occurs, and the expansion radius approaches ? monotonically.

Subject Classification: [43]30.60; [43]25.60.
Creeping waves and lateral waves in acoustic scattering by large elastic cylinders
Authors: Frisk G. V. , Überall H.
Published: October 2005

The connection between creeping wave and flat surface wave theory is established by investigating the limit of acoustic scattering from a solid elastic cylinder imbedded in a fluid, as its radius tends to infinity. After applying the Watson–Sommerfeld transformation to the scattering solution, it is shown analytically that the asymptotic expressions for the residue terms (creeping waves) in the Whispering Gallery mode series combine to form separately both the longitudinal and the transverse lateral waves on a flat surface. The cylindrical Rayleigh wave tends individually towards the flat Rayleigh wave, while the Franz and Stoneley waves disappear.

Subject Classification: [43]30.35; [43]35.54; [43]20.30.
Investigation of some low ultrasonic absorption liquids
Authors: Attal J. , Quate C. F.
Published: October 2005

We report in this paper some results on ultrasonic absorption and velocity of selected low loss liquids and mixtures which may improve the resolving power of the scanning acoustic microscope. We have investigated the effect of electrolytes as a solvent in water which serve to lower the value of α/f2 of water. We also report on our results with hydrogen peroxide and carbon disulfide for these two liquids should allow us to improve the resolution by more than a factor of 2.

Subject Classification: [43]35.24.
Multidimensional encoding within the temporal microstructure of auditory displays. III. Multistate displays
Authors: Pollack Irwin
Published: October 2005

Multistate information was encoded within the temporal microstructure of multivariate auditory displays. Excellent discrimination of a two-dimensional constraint between interpulse interval and pulse amplitude is achieved with 2 to 16 states per variable, but only if other display variables are fixed and the range of the controlled variables is relatively large. Under most of the conditions examined, discrimination of informational constraints within multivariate displays suffers as the number of encoded states is increased beyond two.

Subject Classification :[43]65.75, [43]65.52, [43]65.22.
Psychoacoustic equivalent of period histograms [in memoriam Dr. Russell Pfeiffer]
Authors: Zwicker E.
Published: October 2005

In masking period patterns, the SPL of a just-audible triggered sequence of short high-frequency test-tone pulses varies as a function of their temporal spacing throughout the period of a low-frequency masker. These patterns seem to be a psychocoustic equivalent of neurophysiologically measured period histograms. The duration of the test pulses resembles the bin-width of the histograms. Optimal conditions for the measurement of masking period patterns were ascertained. The influence of the test signal parameters (duration, repetition rate, and frequency) was determined. Masking-period patterns elicited by 50-, 100- and 200-Hz pure-tone maskers of different levels are described and compared with corresponding neurophysiological data. The masking-period patterns show similar periodic maxima and minima as physiological histograms, revealing the time structure of the stimulus. At high masker levels, the patterns seem to reflect nonlinear distortions. For masker frequencies higher than 100 Hz, the difference between maximum and minimum of the patterns decreases and drops to zero at about 500 Hz. This masker frequency corresponds to the psychoacoustically measured critical duration of about 2 msec, up to which the ear is able of resolving temporal fine structure. The correlation of masking-period patterns with physiological data is discussed.

Subject Classification: [43]65.58, [43]65.35, [43]65.75.
Speaker-identifying features based on formant tracks
Authors: Goldstein Ursula G.
Published: October 2005

The formant structure of three diphthongs, four tense vowels, and three retroflex sounds was examined in detail for possible speaker-identifying features. These sounds were spoken five times each in sentence context by ten speakers of General American on one day and by six of the speakers on a second day at least three weeks later. Formant tracks were computed for each sound under investigation using covariance-type pitch-asynchronous linear prediction together with a root-finding algorithm. The interspeaker variability of about 200 measurements made on these formant tracks was compared initially with intraspeaker variability through the calculation of F ratios. Those with average F ratios greater than 60 were evaluated further with a probability-of-error criterion. Features that are potentially most effective in identifying speakers are the minimum second-formant value in [-r], the maximum first-formant value in [-r], the maximum second-formant values of [o] and [-I], and the minimum third-formant value of [-]. The individual differences apparent in these sounds presumably depend more on speaker habits than on vocal-tract anatomy. The error bound predicted for a speaker identification procedure based on these five features is 0.24%. An identification experiment using only the best two features gave 12 errors out of 80 identifications.

Subject Classification: [43]70.65, [43]70.40.
Computer optimization of transducer-array patterns
Authors: Wilson G. L.
Published: October 2005

A linear approximation procedure has been applied to the derivation of shading coefficients for minor lobe control from symmetrical, but possibly irregularly shaped, transducer arrays, for which the relationship between the coefficients and output pressure is linear. Examples are included for the traditional problems of finding optimum coefficients for uniform and low minor lobe response from planar arrays, including one of a ’’honeycomb’’ array on a hexagonal grid, which could not be handled by analytical methods employed hitherto.

Subject Classification: [43]85.40; [43]30.85; [43]20.55; [43]85.84.
Adaptive null processing—a holographic approach and experimental results
Authors: Keating P. N. , Koppelmann R. F. , Mueller R. K. , Steinberg R. F. , Zilinskas G.
Published: October 2005

A software-oriented adaptive null-processing technique for underwater acoustic arrays has been developed and applied to experimental data obtained from a 20×20 square array. This method, which involves spatial homodyning, is holographic in nature, with important similarities to both DICANNE and a recent holographic enhancement technique. The approach is described and evaluated, compared with other methods, and results obtained from its application to experimental underwater data are presented. The technique removes the side lobes from a source image as well as the main lobe in the null direction; a striking example of this in an underwater experiment is given.

Subject Classification: [43]60.30; [43]35.65; [43]30.82.
Energy dissipation in human hand–arm exposed to random vibration
Authors: Cundiff J. S.
Published: October 2005

The problem of correlating the incidence of Raynaud’s phenomenon with exposure to a given vibration environment is well known. It is hypothesized that energy absorbed and dissipated in the hand is energy which can change hand tissue in some manner, and thus may cause injury. Absorbed power is therefore suggested as a parameter which has potential for evaluation of individual worker susceptibility to vibration injury. The arm is represented as a foundation with finite mechanical impedance for the hand model. The hand model parameters, obtainable from experimental impedance measurements on individual subjects, are assumed to be, in general, frequency dependent. The total impedance expression for the system is generalized for the case where the hand is gripping a vibrating handle covered with a layer of viscoelastic material. An expression for absorbed power in this composite system exposed to random vibration is presented.

Subject Classification: [43]40.45.
Instructional-laboratory experiment on temperature dependence of transducer impedance
Authors: Stumpf F. B. , Kosik D. W.
Published: October 2005

An experiment for an advanced undergraduate or graduate laboratory in acoustics is descrived. The temperature dependence of the driving-point impedance curve of a hairpin magnetostrictive-stack transducer was measured in the temperature range 25 °C down to liquid-nitrogen temperature.

Subject Classification: [43]85.20, [43]85.40; [43]10.85.
Trill threshold revisited
Authors: Shonle John I. , Horan Kathryn E.
Published: October 2005

Miller and Heise [J. Acoust. Soc. Am. 22, 637–638 (1950)] defined and measured the trill threshold. They found that a frequency difference of about 15% was needed for two alternating tones to be perceived as such. We made similar measurements between 250 and 4000 Hz and obtained quite different results at all but the 250-Hz frequency. Our results show a frequency dependence similar to that of critical bands, with the trill threshold about one-quarter the size of the appropriate critical bands. In addition we measured the trill threshold in the case of the 1000-Hz signal at modulation rates of 2 and 8 Hz, as well as the 5-Hz rate used by Miller and Heise. There is a significant drop in the trill threshold at the 2-Hz modulation rate.

Subject Classification: [43]65.75, [43]65.54; [43]75.10.
Reply to J. C. Stevens [ J. Acoust. Soc. Am. 59, 473–474 (1976)]
Authors: McFadden Dennis
Published: October 2005

Subject Classification: [43]65.50, [43]65.22.
Model for a ring transducer with inactive segments
Authors: Butler John L.
Published: October 2005

The equation of motion and the equivalent circuit for a segmented ring transducer which incorporates inactive segments is developed. Design considerations are discussed, and it is shown that, although the motion at resonance is dependent on the inactive segments, well below resonance the motion is independent of these segments.

Subject Classification: [43]85.52; [43]30.85.
Acoustic-emission transducer and its absolute calibration
Authors: Hatano Hajime , Mori Eiji
Published: October 2005

A new method is developed for absolute calibration of acoustic-emission transducers using a reciprocity technique in a Rayleigh-wave sound field. It is applied to practical transducers, and their sensitivity is obtained over a frequency range of 100 kHz to 1 MHz. The result is compared with frequency spectrum of an actual acoustic emission signal from a large structure detected by an identical transducer. It is shown that practical characteristics of transducers can be estimated with ease and repeatability in an acoustical environment similar to that of structures such as pressure vessel walls.

Subject Classification: [43]40.42; [43]85.40.
Transmissibility across simply supported thin plates. II. Rectangular plates with loading masses and straight ribs
Authors: Ochs J. B. , Snowdon J. C.
Published: October 2005

The transmissibility of thin, simply supported, rectangular aluminum plates of like dimensions has been determined experimentally in the frequency range 25–3025 Hz. Comparison has been made between the results of measurements on an unloaded plate, on plates loaded centrally by concentrated masses of small and large contact area, and on plates loaded by seven different straight-rib configurations, one of which utilized X-cut ribs that stretched diagonally between opposite plate corners. The additional mass was always equal to that of the plates so that the effectiveness of the mass in reducing transmissibility could be evaluated as a function of its geometry. The experimental transmissibilities of the unloaded and centrally mass-loaded plates were in excellent agreement with theoretical prediction. At frequencies above the fundamental resonance of the plates, the greatest overall reduction in transmissibility was provided by the X-cut ribs; whereas, at the fundamental resonance itself, the greatest reduction was provided by a single central rib placed parallel to the shorter plate sides.

Subject Classification: [43]40.24, [43]40.20.
Perception of noise transmitted through barriers
Authors: Aylor Donald E. , Marks Lawrence E.
Published: October 2005

Perceived loudness of noise transmitted through barriers was scaled by human observers outdoors. Using the method of magnitude estimation, subjects compared the relative loudness of a narrow band of noise transmitted through barriers of different solidity. When the subjects were blindfolded, and thus unable to see the barriers, loudness was judged the same under all conditions. When the barriers were visible, however, sizable differences in loudness emerged: When the barrier only partially obscured sight of the sound source, loudness was judged less than when there was no intervening barrier; but, when the barrier totally obscured sight of the source, loudness was judged greater than when the source could be seen, either in whole (no barrier) or in part. These results point out the complex nature of the psychological effect of barriers on perceived noise levels.

Subject Classification: [43]65.50, [43]65.22; [43]50.20; [43]55.75.
Effect of temperature on cochlear responses during and after exposure to noise
Authors: Drescher Dennis G.
Published: October 2005

Anesthetized chinchillas were maintained in the quiet for 24–48 h with virtually no loss of maximum voltage or sensitivity of cochlear microphonics (CM). Changes in body temperature and cochlear temperature from 29° to 39 °C had little effect on normal CM. With presentation of steady octave-band noise with center frequency of 1 kHz at 90 dB SPL overall, CM decreased and approached an asymptote at a rate dependent on the temperature of the preparation. The rate of reduction was less at low temperatures than at high temperatures. With termination of the noise, an initial rapid recovery of CM preceded a slow recovery toward normal CM values. The slow recovery was inhibited at low temperatures, and could be enhanced by raising the temperature. These studies indicate that noise-induced reduction of CM may be linked to processes of energy metabolism and/or may involve temperature-dependent structural changes that do not affect normal cochlear response.

Subject Classification: [43]65.66, [43]65.40, [43]65.35.
Numerical investigation of nonlinear oscillations of gas bubbles in liquids
Authors: Lauterborn Werner
Published: October 2005

Forced oscillations of a spherical gas bubble in an incompressible, viscous liquid (water) are calculated numerically. The information gathered is mainly displayed in the form of frequency response curves of the steady-state solutions showing the harmonics, subharmonics, and ultraharmonics. Bubbles oscillating ultraharmonically at frequencies below the main resonance may emit half the driving frequency. This fact gives rise to a new explanation for the occurrence of the first subharmonic in the spectrum of the cavitation noise in ultrasonic cavitation.

Subject Classification: [43]30.70, [43]30.75.
Noise of ears and microphones
Authors: Killion Mead C.
Published: October 2005

Although it is well known that the internal noise of the human ear is less than that of many microphones, little has been published since Baerwald (1940) directly comparing the noise level of ears and microphones. When a microphone is to be used in a hearing aid, it is of interest to know how soft a sound the wearer can hear if he turns the gain up far enough. If the noise spectrum of the microphone is known, the ’’aided pure-tone threshold’’ which can be achieved with that microphone can be calculated by utilizing the extensive literature on the masking of pure tones by noise. Following French and Steinberg [J. Acoust. Soc. Am. 19, 90–119 (1947)], one can turn the tables and calculate the apparent noise spectrum of the ear considered as a microphone. Such a calculation indicates that an acute young ear has an apparent noise level equivalent to that of a microphone with an A-weighted noise level of about 20 dB SPL. Experimental verification has been obtained on a new hearing aid microphone designed to be quieter than the human ear. A brief comment on the clinical implications of these results for hearing aid evaluation is included.

Subject Classification: [43]65.50, [43]65.80; [43]85.62.
Deep scattering layer spectra in the eastern North Pacific
Authors: Johnson Richard K.
Published: October 2005

Measurements by several investigators of the deep scattering layer are consistent with the hypothesis that the dominant scatterers are fishes with gas-filled swimbladders of 1.6- to 3.1-mm radius. The population density of these fish is estimated from the acoustic results to be between 0.5 and 15/1000 m3.

Subject Classification: [43]30.40.
Experiments on porous blades as a means of reducing fan noise
Authors: Chanaud R. C. , Kong Ning , Sitterding R. B.
Published: October 2005

In a study of ways to reduce the sound power produced by propeller fans, the performance of various porous blades was compared with that of solid blades. It was found that a porous-bladed fan could produce flow with characteristics similar to that produced with a solid-bladed fan, with a reduction of about 5 dB in the sound at the cost of a slight reduction in static efficiency.

Subject Classification: [43]50.30, [43]50.40, [43]50.45.
Influence of mean sound speed on acoustic transmission through an internal wave
Authors: Lieberman G. A. , Jacobson M. J. , Siegmann W. L.
Published: October 2005

A major purpose of this paper is to investigate the influence of mean sound-speed structures on sound transmission in the presence of a single-frequency internal wave. A cw signal is transmitted through a shallow ocean over a range that is small compared to the wavelength of the internal wave. A constant value of the Brunt–Vaisala frequency is assumed, and this value is taken as a parameter of the model. The total field associated with refracted/bottom-reflected rays is studied, and the effect of the internal wave on total-field phase and transmission loss is examined. Then, the maximum variation of the phase is investigated for different mean sound-speed structures and internal-wave amplitudes. This variation shows a general downward trend, as bottom sound speed increases, and an oscillatory behavior possibly due to rapid changes in the rate of change of phase with respect to mid-depth sound speed. A simple mathematical model is constructed to explain the dominant decreasing trend. Phase variation is shown to vary linearly with bottom sound speed and to be proportional to wave amplitude, range, and acoustic frequency. It is inversely proportional to ocean depth.

Subject Classification: [43]30.20, [43]30.25.
Effect of the parallel reflecting surfaces of a transducer on the resulting pulse shape
Authors: Altman Harry E. , Beyer Robert T.
Published: October 2005

Calculations are made of the pulse shapes for sound waves reflected from a plane transducer. These show the effect of reflections from the two parallel surfaces and their relation to pulse width and transducer thickness. Illustrations are given for several representative combinations of samples and backing media, together with photographs of pulse shapes obtained experimentally.

Subject Classification: [43]35.80; [43]85.40; [43]20.30.
Auditory filter shapes derived with noise stimuli
Authors: Patterson Roy D.
Published: October 2005

A wide-band noise having a deep notch with sharp edges was used to mask a tone. The notch was centered on the tone, and threshold was measured as the width of the notch was increased from 0.0 to 0.8 times the tone frequency (0.5, 1.0, or 2.0 kHz). The spectrum level of the noise was 40 dB SPL. If it is assumed that the auditory filter is reasonably symmetric at these intensities, then the shape of the filter centered on the tone can be estimated from the first derivative of the curve relating tone threshold to the width of the notch in the noise. The 3-dB bandwidths of the filters obtained were about 0.13 of their center frequency. In the region of the passband, the Gaussian curve provides a good approximation to the shape of the derived filters. The equivalent rectangular bandwidths of the Gaussian approximations are about 0.20 of their center frequency, which is comparable to the critical-band estimates of R. Zwicker, G. Flottorp, and S. S. Stevens [’’Critical bandwidth in loudness summation,’’ J. Acoust. Soc. Am. 29, 548–557 (1957)]. The Gaussian approximation cannot be used outside the passband, because the tails of the derived filters do not fall as fast as the Gaussian curve.

Subject Classification: [43]65.58, [43]65.35; [43]80.50.
Detectability of auditory signals presented without defined observation intervals
Authors: Watson Charles S. , Nichols Thomas L.
Published: October 2005

Ability to detect tones in noise was measured without defined observation intervals. Latency density functions were estimated for the first response following a signal and, separately, for the first response following randomly distributed instances of background noise. Detection performance was measured by the maximum separation between the cumulative latency density functions for signal-plus-noise and for noise alone. Values of d′, estimated by this procedure, were approximately those obtained with a 2-dB weaker signal and defined observation intervals. Simulation of defined- and nondefined-interval tasks with an energy detector showed that this device performs very similarly to the human listener in both cases.

Subject Classification: [43]65.58, [43]65.75, [43]65.50, [43]65.68.
Effect of temperature on harmonic content of microphonic response from the second cochlear turn of chinchilla
Authors: Drescher Dennis G. , Gibian Gary L.
Published: October 2005

Cochlear microphonic responses of chinchilla to tones from 20 to 110 dB SPL were examined with a fast-Fourier-transform algorithm. Distortion of microphonics recorded from the second cochlear turn (CM2) for acoustic input at 0.225 kHz was found to increase rapidly above 50 dB SPL. Like the input–output function for the complete CM2 response, the input–output functions for the harmonics saturated near 80 dB SPL. Changes in temperature of the preparation from 29° to 39 °C had minimal effect on the pattern of the harmonics examined. These results are consistent with the hypothesis that moderate changes in temperature act primarily on metabolism supporting CM generation and not on the transduction processes per se.

Subject Classification: [43]65.40, [43]65.66, [43]65.35.
Eye color and susceptibility to TTS
Authors: Hood J. D. , Poole J. P. , Freedman L.
Published: October 2005

Controversy has arisen over the claim that melanin content of the iris as determined by eye color bears a direct relationship to susceptibility to temporary threshold shift (TTS). Further observations have now been carried out aimed at extending the range of stimulus intensities hitherto employed together with an investigation into the possible significance of differences in the methodology. The evidence which the data brings to bear in support of the reported correlation is not particularly strong at stimulus intensities of 80 dB (HTL re ISO, 1964), but becomes more persuasive at higher intensities. At 120 dB the evidence seems conclusive, with blue-eyed subjects exhibiting significantly more TTS than brown-eyed subjects. Since this relationship is evident only when the threshold determinations are carried out using continuous tones and is absent with pulsed tones, it is concluded that the underlying mechanism is predominantly auditory adaptation and not fatigue.

Subject Classification: [43]65.66.
Comments on ’’Tissue concentrations of ethacrynic acid and inhibition of enzymes and electrophysiological responses in the cochlea’’ [ J. Acoust. Soc. Am. 58, S31 (A) (1975)]
Authors: Paloheimo S. , Thalmann R.
Published: October 2005

The purpose of this communication is to point out an error in our determination of the concentrations of 14C–ethacrynic acid in the stria vascularis.

Subject Classification: [43]65.28, [43]65.40.
Effect of silence between tones on auditory stream segregation
Authors: Dannenbring Gary L. , Bregman Albert S.
Published: October 2005

The present study investigates the effect on auditory stream segregation of the duration of silent gaps between items of a repeating sequence of sine tone stimuli. While previous investigators had shown that gaps reduced the tendency for items to segregate, the present experiment showed that this was not the case; rather, in adjusting tone durations for stream segregation thresholds, subjects simply compensated for increased gap duration, keeping the total time (tone duration plus gap duration) constant.

Subject Classification: [43]65.75, [43]65.54, [43]65.68.
Comments on ’’Temporal interactions within a phrase and sentence context’’
Authors: Ohala John J. , Lyberg Bertil
Published: October 2005

The interpretation given in the subject article to the incidence of negative correlations between the durations of adjacent speech segments, viz., that they show evidence of temporal compensation, is criticized. It is shown that the negative correlations are most likely due to measurement error and to the author’s normalization of the duration of his test utterances.

Subject Classification: [43]70.40, [43]70.70, [43]70.20.
Finite-amplitude losses in spherical sound waves
Authors: Merklinger Harold M. , Mellen Robert H. , Moffett Mark B.
Published: October 2005

An approach suggested by Westervelt [3rd Int. Congr. Acoust., Stuttgart, 1959] has previously been used to predict with remarkable accuracy the excess absorption due to nonlinear effects in a plane, traveling sound wave. The same approach is applied here to spherically diverging sound waves. A number of cases of practical importance in underwater acoustics are evaluated and compared with other theoretical results.

Subject Classification: [43]25.22; [43]30.75.
Infrasound from convective storms. III. Propagation to the ionosphere
Authors: Jones R. Michael , Georges T. M.
Published: October 2005

We model mathematically the spectral features of infrasound observed in the ionosphere and believed to be radiated by severe thunderstorms. We explain the dominant 2–5-min wave period as an effect of atmospheric filtering; shorter periods are excessively attenuated by absorption in transit to the ionosphere, and longer periods are attenuated in portions of the atmosphere where the waves are evanescent because their frequencies are below the acoustic cutoff. An observed spectral ’’fine structure’’ within the 2–5-min band is explained in terms of resonant interactions between the waves and the atmospheric temperature structure. Accurate quantitative modeling of all these details of the storm-to-ionosphere transmission coefficient requires numerical integration of the acoustic-gravity wave equation, including the effects of ground reflection, absorption, and partial reflections in the atmosphere.

Subject Classification: [43]28.30.
Relationship of Doppler ultrasonic scattered signal characteristics to flow and beam parameters
Authors: Albright Robert J.
Published: October 2005

The specific dependence of the properties of a cw Doppler ultrasonic scattered signal, and of its autocorrelation and spectral density functions, on various scatterer flow parameters and diagnostic signal beam parameters is shown. These factors include the scatterer average velocity profile and the extent of any turbulence together with the signal beam angle and beam width.

Subject Classification: [43]30.40; [43]35.65; [43]20.15, [43]20.30.
Mechanical impedance of human headbones (forehead and mastoid portion of the temporal bone) measured under ISO/IEC conditions
Authors: Flottorp Gordon , Solberg Sigurd
Published: October 2005

Mechanical impedances of the mastoid portion of the temporal bone and of the forehead are presented for 60 human subjects of both sexes and of ages between 9 and 71 years. Measurements were carried out using a plane circular surface of 1.75 cm2 and a static force of 5.4 N (ISO/IEC conditions). Impedance is found to vary with age and to a lesser extent with sex. Results are consistent with earlier measurements carried out under somewhat different conditions, but deviate rather substantially at most frequencies from the recommended ISO/IEC mechanical impedance for an artificial headbone. A study of the influence of variations in the mechanical headbone impedance upon bone vibrator performance by means of an analogous electrical network is reported.

Subject Classification: [43]65.64; [43]85.20.
Correlates of combination tones observed in the response of neurons in the anteroventral cochlear nucleus of the cat
Authors: Smoorenburg Guido F. , Gibson Mary Morton , Kitzes Leonard M. , Rose Jerzy E. , Hind Joseph E.
Published: October 2005

Neurons in the anteroventral cochlear nucleus of the cat respond to combination tones of the forms f2−f1 and f1−n (f2−f1), where n is a small positive integer 1, 2, 3,.... The most easily observed combination tones are f2−f1 and 2f1−f2. In general, a combination tone is effective if three conditions are fulfilled: (1) the combination-tone frequency must fall within the pure-tone response area of the neuron; (2) the intensity levels of the primaries must be appropriate; and (3) the separation of the primary frequencies cannot be unduly large. For any form of combination tone, a combination-tone response area could be plotted by fixing f1 at some level and varying f2 in small steps. The actual frequency of the combination tone could be determined from the timing of the discharges for all neurons whose discharges are phase locked. The combination-tone response areas indicate that the response to a given form of combination tone is optimal when the combination frequency is at or near the best frequency of the neuron. Moreover, the combination-tone response areas are similar in width to the pure-tone response area of the neuron. These findings suggest that the neuron responds to combination tones as if such tones were actually delivered to the ear. It was further found that the combination-tone frequencies that activate the neuron may be several octaves below the frequencies of the two primaries that produce the combination tone. Combination-tone threshold and suprathreshold studies show that the combination-tone level increases with decreasing separation of the two stimulus components. Levels of the combination tones expressed in equivalent decibels of SPL increase approximately proportionately with stimulus level (L1=L2) for both f2−f1 and 2f1−f2. Furthermore, for both these combination tones, the combination-tone level as a function of L2 (L1 fixed) shows a peaked curve with the maximum occurring when L2 is about equal to L1. The types of combination tones encountered and the effects of variations in stimulus frequency are in accord with psychophysical findings. The effect of stimulus level on combination tone level is in agreement with psychophysical observations for 2f1−f2 but seems to disagree with most psychophysical data for f2−f1 at higher stimulus frequencies. The results suggest that a marked nonlinearity is involved in cochlear processing, at least in the 40- to 90-dB-SPL range.

Subject Classification: [43]65.56, [43]65.42, [43]65.40.
The cochlear compromise
Authors: Zweig G. , Lipes R. , Pierce J. R.
Published: October 2005

It is conjectured that the design of the cochlea is influenced by two conflicting requirements: (1) the cochlea should act as a precise frequency analyzer and (2) waves propagating along the basilar membrane should be transmitted without reflections. Accurate frequency analysis is possible only if the mechanical properties of the cochlea change rapidly with distance along the basilar membrane. Reflections of waves traveling on the basilar membrane will be negligible, however, only if these same mechanical properties change slowly. A compromise between these two requirements is possible if a loss constant δ related to the sharpness of response of the basilar membrane to a pure tone is related to the number N of wavelengths of the wave on the basilar membrane [N/(δ)1/2?1]. Furthermore, if sizable changes in the displacement occur only over distances larger than the width of a hair cell, then δ must be larger than the ratio of the width w of a hair cell to the distance d along the basilar membrane over which the characteristic frequency changes by an octave [δ≳4N (2δ)1/2 w/d]. These remarks are made explicit in a transmission-line model of cochlear mechanics. A simple closed-form solution of the equations, which agrees with a numerical solution, is given. The solution is compared with Mössbauer measurements of basilar membrane motion. Agreement with experiment is good if N and δ are chosen appropriately. These values are consistent with both of the conjectured relations and indicate that δ is the same order of magnitude as its lowest possible value.

Subject Classification: [43]65.26, [43]65.35.
Poster sessions at the 89th Meeting of the Acoustical Society of America
Authors: Chial Michael R. , Hopper Robert , Whitehead Jack L. , Smith Alfred G.
Published: October 2005

Behavioral observations of communication interaction patterns were gathered for traditional and ’’poster paper’’ presentations at the 89th Meeting of the Society (7–11 April 1975, Austin, Texas). Affective reactions of poster paper authors and audience members were also surveyed. The overall response to poster sessions was very positive, suggesting continuation of the new mode of technical communication. Poster paper authors were somewhat more positive in their responses than other participants. Although poster sessions produced much more verbal interaction, patterns of interaction did not appear to differ from those observed in traditional presentations. Several problems particular to poster sessions were identified and suggestions for improvement are offered.

Subject Classification: [43]05.50; [43]10.85.
Hearing sensitivity of the mongolian gerbil, M
e
r
i
o
n
e
s u
n
g
u
i
c
u
l
a
t
i
s
Authors: Ryan Allen
Published: October 2005

Mongolian gerbils were trained to respond to pure tones in a shock-avoidance task. The animals proved to be readily trainable and behaviorally stable. Thresholds were obtained by a method of limits and, in the case of one animal, by generating psychrometric functions. The gerbil responds to frequencies between 0.1 and 60.0 kHz. For pure tones between 1.0 and 16.0 kHz, the threshold of hearing averages 4.6 dB SPL. Between 1.0 and 0.1 kHz, sensitivity declines at a rate of 12 dB/octave. Between 16.0 and 40.0 kHz, threshold increases at a rate of 13 dB/octave, and above 40.0 kHz at a rate of 66 dB/octave. Thresholds derived from psychometric functions were essentially identical to those obtained by the method of limits. Hearing in this species is consistent with its size and anatomical characteristics.

Subject Classification: [43]80.50; [43]65.50.
Theory of normal modes and ultrasonic spectral analysis of the scattering of waves in solids
Authors: Pao Yih-Hsing , Mow C. C.
Published: October 2005

A theory of the spectral analysis of the scattering of elastic waves is presented and illustrated with numerical results for the scattering by a circular cylindrical fluid inclusion in a solid. When the spectral frequencies are nearly equal to the real parts of the principal frequencies of the fluid inclusion in free vibration, the power spectrum of the scattered pulses undergoes a rapid rise and fall in magnitude because of the selective transmission of an incident wave. The conspicuous peaks and valleys of the backward and forward scattering spectra can be identified with the overtone frequencies of the two lowest normal modes of the cylinder, from which the characteristics of the fluid inclusion, the ratio of the wave speed to radius, can be determined.

Subject Classification: [43]20.15, [43]20.30.
Reflection of acoustical waves at porous boundaries
Authors: Roetman E. L. , Kochhar Ram P.
Published: October 2005

The reflection and transmission of plane harmonic waves impinging from air to the plane face of porous material occupying a semi-infinite space as well as with finite thickness is considered. The variation of these coefficients with the angle of incidence and various parameters (frequency, permeability, etc.) is illustrated for certain porous materials. The results obtained indicate that the transmission coefficient remains the same under the assumption of velocity potential (there is no velocity potential in general in the porous material) while the reflection coefficient changes significantly.

Subject Classification: [43]20.30, [43]20.35.