bluuebunny/crossref_metadata_2025 huggingface dataset:
Acoustic measurement of erythrocyte compressibility
Authors: Shung K. K. , Krisko B. A. , Ballard J. O.
Published: October 2005

Adiabatic compressibility of red blood cells obtained from humans using a modified ultrasound velocity technique has been determined and correlated to the mean cellular hemoglobin concentration of the red blood cells. The ultrasound technique has an accuracy of better than 0.1%. The results show a mean adiabatic compressibility of 34.814×10−12±0.861 cm2/dyn for an average mean cellular hemoglobin concentration of 32.12±1.51 g%. The relationship between the MCHC and compressibility was investigated by suspending erythrocytes in saline of different NaCl concentrations. A correlation coefficient of 0.932 was obtained based on linear regression analysis.
Effects of masker duration in pure-tone forward masking
Authors: Kidd G. , Feth L. L.
Published: October 2005

The masking of one tone by a preceding tone (forward masking) was studied as a function of the duration of the masker. In general it was found that forward masking increased with increasing masker duration for the range of durations used (35 to 500 msec). The functions relating masked probe threshold in decibels to the logarithm of masker duration were well described by straight lines. The rate of growth of forward masking as a function of masker duration was greatest for relatively high masker levels and frequencies.
Gap detection in hearing-impaired chinchillas
Authors: Giraudi-Perry D. M. , Salvi R. J. , Henderson D.
Published: October 2005

Auditory temporal resolution is known to deteriorate with sensorineural hearing loss; however, there is considerable intersubject variability in human studies. The purpose of the present study was to obtain measures of temporal resolution in the chinchilla as the degree of noise-induced hearing loss was systematically varied. Gap-detection thresholds, a measure of temporal resolution, were evaluated at four levels of noise-induced asymptotic threshold shift (ATS). Gap thresholds were normal when the pure-tone thresholds were elevated approximately 15 dB. With a hearing loss of approximately 30 dB, the gap thresholds were longer than normal if compared at the same sound pressure level, but within normal limits if compared at the same sensation level. When the hearing loss exceeded 40 dB, gap thresholds were longer than normal both in terms of sound pressure level and sensation level. These results show that there is an orderly breakdown in temporal resolution as the degree of noise-induced ATS increases. The results are related to neural data and models of temporal resolution.
Prediction of vibrotactile masking functions
Authors: Gescheider George A. , Verrillo Ronald T. , Van Doren Clayton L.
Published: October 2005

Threshold shifts for the detection of vibrotactile test stimuli were determined as a function of the intensity of a masker. The masking stimulus, narrow-band noise centered at 275 Hz, and the test stimulus, a 15-, 50-, 80-, or 300-Hz sinusoidal burst, were applied to the same site on the thenar eminence of the hand. The intensity of the masker was varied over a range of 0 to 52 dB SL. The results support the hypothesis that the detection of vibrotactile stimuli is mediated by at least two receptor systems which do not mask each other.
Correlation of phase and amplitude fluctuations at hydrophones spaced one-half to two wavelengths apart
Authors: Mangano D. T. , Broek H. W.
Published: October 2005

An experiment was performed at sea to study the temporal properties of amplitude and phase coherence of cw signals received on a linear array of four deep bottomed hydrophones with consecutive spacings of 287, 22, and 890 ft. The source was suspended at each of several depths from a drifting ship in the second convergence zone, and activated at frequencies of 115, 200, and 400 Hz for an hour at a time each. The average received signal amplitude and the average cosine of the phase difference between hydrophones 22 ft apart for 8.73-min samples were found to be related. When average amplitude was large, the average cosine was 1.0; when amplitude was small (e.g., 20 dB less), the cosine was near zero. Within the 8.73-min period also, large rapid phase variations often occurred accompanied by large variations in signal amplitude. The signal gain of the array of four receivers was found to be similarly related to the average hydrophone power. These results support previous theoretical predictions. Phase and amplitude oscillations which occurred at frequencies around 0.1 Hz are attributed to interaction of the signal with the sea surface.
Generation of transient cavities in liquids by microsecond pulses of ultrasound
Authors: Flynn H. G.
Published: October 2005

Calculations reported here show that small gas nuclei in a liquid acted on by microsecond ultrasonic pulses may grow into transient cavities that collapse violently. The maximum pressures and temperatures generated by such collapsing cavities are found in these calculations to be of the order of 1000 to 70 000 bars and 1000 ° to 20 000 °K.
Spectra of transient waves in elastic plates
Authors: Weaver Richard L. , Pao Yih-Hsing
Published: October 2005

Frequency spectra of transient Rayleigh–Lamb waves in a plate are evaluated by two methods, a direct numerical integration (FFT), and an asymptotic calculation of the theoretical responses. A simple formula is developed for the interference pattern of the spectra of two or more modes of progressing waves, which is then applied to interpret the complex frequency spectra of the waves in a plate over a wide range of frequency. These interpretive techniques may be applicable to source characterization of acoustic emission.
Integral representations for edge diffraction
Authors: Gautesen A. K.
Published: October 2005

For the problem of diffraction by a plane obstacle of a point source, a line integral representation for derivatives of the field is derived. From this representation a line integral of the field is obtained which is asymptotically equivalent to Keller’s theory of geometrical edge diffraction.
A least-square iterative technique for solving time-domain scattering problems
Authors: Herman Gérard C. , van den Berg Peter M.
Published: October 2005

An alternative method for the numerical solution of time-domain integral equations pertaining to three-dimensional, transient scattering problems is developed and applied to two representative acoustic scattering configurations. It is based on the iterative minimization of an integrated square error. For the cases considered, the method gives more accurate results than the frequently used ‘‘marching-on-in-time’’ method (within comparable computation times).
Normal mode theory: The role of the branch-line integral in Pedersen–Gordon type models
Authors: Hall Marshall
Published: October 2005

The acoustic field at the cutoff frequency of a shallow water channel described by Stickler [J. Acoust. Soc. Am. 57, 856–861 (1975)] is calculated using the Pedersen–Gordon normal mode model. As the (negative) sound-speed gradient in the terminal layer approaches zero, the values of the acoustic field at various positions are found to approach well defined limits. These limits are in excellent agreement with the corresponding values obtained by Stickler for the same profile terminated by an iso-speed layer. Stickler’s calculation included a significant Branch Line Integral (BLI) contribution, whereas the present calculation does not, although it does include the first mode of the first family, and many modes of the second family, of ‘‘Freehafer’’ modes. This agreement demonstrates that, as argued by Freehafer, there is no BLI in the solution of the wave equation for a stratified half-space that has a free surface, a piecewise analytic sound-speed profile, and a sound speed that approaches zero at infinite distance from the surface.
Pressure transfer function of a JT15D nozzle due to acoustic and convected entropy fluctuations
Authors: Miles J. H. , Krejsa E. A.
Published: October 2005

An acoustic transmission matrix analysis of sound propagation in a variable area duct with and without flow is extended to include convected entropy fluctuations. The boundary conditions used in the analysis are a transfer function relating entropy and pressure at the nozzle inlet and the nozzle exit impedance. The nozzle pressure transfer function calculated with this analysis is compared with JT15D turbofan engine nozzle data. The one-dimensional theory for sound propagation in a variable area nozzle with flow but without convected entropy is good at the low engine speeds where the nozzle exit Mach number is low (M=0.2) and the duct exit impedance model is good. The effect of convected entropy appears to be so negligible that it is obscured by the inaccuracy of the nozzle exit impedance model, the lack of information on the magnitude of the convected entropy and its phase relationship with the pressure, and the scatter in the data. It appears an improved duct exit impedance model is required at the higher engine speeds where the nozzle exit Mach number is high (M=0.56) and at low frequencies (below 120 Hz). Nevertheless, the results show the one-dimensional sound propagation model does apply to the JT15D turbofan engine nozzle data.
Numerical evaluation of the Rayleigh integral for planar radiators using the FFT
Authors: Williams Earl G. , Maynard J. D.
Published: October 2005

Rayleigh’s integral formula is evaluated numerically for planar radiators of any shape, with any specified velocity in the source plane using the fast Fourier transform algorithm. The major advantage of this technique is its speed of computation—over 400 times faster than a straightforward two-dimensional numerical integration. The technique is developed for computation of the radiated pressure in the nearfield of the source and can be easily extended to provide, with little computation time, the vector intensity in the nearfield. Computations with the FFT of the nearfield pressure of baffled rectangular plates with clamped and free boundaries are compared with the ‘‘exact’’ solution to illuminate any errors. The bias errors, introduced by the FFT, are investigated and a technique is developed to significantly reduce them.
Frequency of occurrence of two- and three-word sequences in English
Authors: Umeda Noriko , Kahn Daniel
Published: October 2005

We analyzed a large corpus of written English to determine the most common two-word and three-word sequences and their frequencies. We disallowed sequences with internal punctuation in an attempt to limit the search to sequences likely to be pronounced as a unit. There are obvious applications of the results to word-based speech synthesis; we feel our frequency tables will be useful to linguists, psychologists, and workers in automatic speech recognition as well.
The probability of exciting an elastic structure with a given resonant amplification factor
Authors: Garrelick Joel M.
Published: October 2005

Given a random excitation frequency, a crude approximation for the probability (PX ) of exciting an arbitrary elastic structure with a resonant amplification factor (X) is given as PX =(2/π)/X.
Input and transfer response of brass wind instruments
Authors: Elliott Stephen , Bowsher John , Watkinson Peter
Published: October 2005

Relationships among the various acoustical parameters which may be associated with musical wind instruments are explored. By defining appropriate input and output planes and assuming a linear, time-invariant system, many of the concepts of transmission line theory are applicable. The real and imaginary parts of the propagation constant may be deduced from measurements of the input impedance and transfer function and used to study the effects of wall condition, for example. The influence of the mouthpiece is very different for the trumpet and trombone, and the concept of a unique impedance ‘‘seen’’ by the player is shown to be misleading. The power efficiency of the instruments between input and output planes may be calculated from measured data but more information is needed on the radiation impedance at the bell before detailed estimates of the components due to the regeneration process may be separated from internal losses in the instrument. Finally, it is shown that use of the time domain is very helpful when the influence of particular parts of the instrument is being studied.
Perception of short-term spectral cues for stop consonant place by normal and hearing-impaired subjects
Authors: Van Tasell Dianne J. , Hagen Lawrence T. , Koblas Linda L. , Penner Sharon G.
Published: October 2005

The purpose of the experiments described in this paper was to investigate the use by normal and hearing-impaired subjects of the acoustic information at syllable onset for identification of the place feature of synthetic voiced stop consonants. Two synthetic speech continua served as stimuli. The full-length continuum comprised 14 syllables that varied from /ba/ to /da/ to /ga/. The 14 stimuli of the short-stimulus continuum were truncated versions of the full-length syllables; each contained a burst portion plus two glottal pulses. All normal subjects categorized the full-length stimuli accurately and consistently, but only two of seven normals performed equally well with the short-stimulus continuum. The short-stimulus performance of the remaining five normals improved after training, but remained significantly poorer than their performance with the full-length stimuli, indicating that the information at stimulus onset did not provide all the necessary place information for those subjects. Hearing-impaired subjects’ identification of the full-length stimuli was only slightly less consistent than the normals’, and was highly correlated with their identification of stop consonant place in natural syllables. Their post-training performance with the short stimuli did not differ from that of the trained normal group. These results indicate that various forms of signal distortion imposed by sensorineural hearing loss may, under certain conditions, have negligible effects on subjects’ use of acoustic place cues when those cues are at suprathreshold levels.
Magnitude estimation of degraded speech quality by normal- and impaired-hearing listeners
Authors: Lawson Gary D. , Chial Michael R.
Published: October 2005

Speech quality magnitude estimates (SQME’s) were obtained from 12 normal-hearing and 12 sensorineurally impaired-hearing listeners on connected speech samples degraded by changing low-pass filter cutoff frequency, high-pass filter cutoff frequency, or percent total harmonic distortion (THD) by linear rectification. Log SQME’s varied linearly with log bandwidth for filtered signals and with log percent undegraded (100−% THD) for linearly rectified signals. Significant variations were found among the slopes of the log–log functions for degradation modes and group-by-degradation mode interactions. Slope differences appeared to represent differential sensitivity of the listeners to changes in mode and degree of degradation. The findings are sufficiently encouraging to suggest that direct scaling procedures be employed in future studies of the evaluation of communication systems and the perception of complex signals.
The deterioration of hearing with age: Frequency selectivity, the critical ratio, the audiogram, and speech threshold
Authors: Patterson Roy D. , Nimmo-Smith Ian , Weber Daniel L. , Milroy Robert
Published: October 2005

The frequency selectivity of the auditory system was measured by masking a sinusoidal signal (0.5, 2.0, or 4.0 kHz) or a filtered-speech signal with a wideband noise having a notch, or stopband, centered on the signal. As the notch was widened performance improved for both types of signal but the rate of improvement decreased as the age of the 16 listeners increased from 23 to 75 years, indicating a loss in frequency selectivity with age. Auditory filter shapes derived from the tone-in-noise data show (a) that the passband of the filter broadens progressively with age, and (b) that the dynamic range of the filter ages like the audiogram. That is, the range changes little with age before 55, but beyond this point there is an accelerating rate of loss. The speech experiment shows comparable but smaller effects. The filter-width measurements show that the critical ratio is a poor estimator of frequency selectivity because it confounds the tuning of the system with the efficiency of the signal-detection and speech-processing mechanisms that follow the filter. An alternative, one-point measure of frequency selectivity, which is both sensitive and reliable, is developed via the filter-shape model of masking.
Vertical and horizontal sound localization in primates
Authors: Brown Charles H. , Schessler Teryl , Moody David , Stebbins William
Published: October 2005

Minimum audible angles for localization in the vertical and horizontal planes were psychophysically determined in Old World monkeys (Macaca). In the vertical condition the test stimuli consisted of primate vocalizations and bands of noise. Minimum audible angles ranged from 3° to greater than 20° for signals of various bandwidths. The acuity of vertical localization was dependent upon the high-frequency content of the signal. Two of the three monkeys were unable to vertically localize sounds if the high-frequency limit of the signal was below 2000 Hz. The acuity of horizontal localization was tested for pure tones 500, 2000, and 8000 Hz in frequency, positioned at several referent locations in the right frontal quadrant. The acuity of horizontal localization decreased as the test azimuth was displaced from the midline. Minimum audible angles ranged from approximately 4° to greater than 20° and varied as a function of test azimuth.
Gain and efficiency of a traveling wave heat engine
Authors: Ceperley Peter H.
Published: October 2005

Gain and efficiency equations are derived for a traveling wave heat engine, a device in which acoustic traveling waves force gas within a differentially heated regenerator to undergo a Stirling thermodynamic cycle and transform energy between thermal and acoustic forms. This derivation assumes nonturbulent flow conditions, a linear drag coefficient, a constant heat exchange coefficient, and neglects regenerator end effects. The complex characteristic impedance, gain, and efficiency are calculated for a thin slice of the regenerator in terms of dimensionless variables. With a Prandlt number of 0.7, the equations predict an efficiency of 70% that of an ideal Carnot cycle, and gain of 85% of that of theoretical maximum gain when fN ≡ωτ=0.003 and T′N≡ (dT/dx)T−1CIτ=0.4, where ω is the acoustic angular frequency, τ is the thermal time constant for the heat exchange process, dT/dx is the regenerator temperature gradient, and CI is the isothermal velocity of sound. In general, the equations predict that efficient high gain regenerators are quite short, have a large temperature gradient, and operate at low acoustic frequencies. Traveling wave heat pumps are also discussed and are very similar.
Choice of target and accuracy of measurement in suspended sphere ultrasonic radiometry
Authors: Chivers R. C. , Anson L. W.
Published: October 2005

The results of calculations are presented indicating the ways in which the form of the frequency dependence of the radiation force function Yp for spherical targets is affected by variations in the material parameters of the sphere, in temperature, and of the fluid surrounding the sphere. It is shown that the group II materials have less than 1% variation in Yp over significant frequency ranges for variations of ±5% in the wave velocities in the sphere. The relation of these calculations to experimental arrangements is discussed, with the conclusion that suspended sphere radiometry should be capable of much higher accuracy than has hitherto been achieved.
Physical and acoustical properties of zooplankton
Authors: Greenlaw Charles F. , Johnson Richard K.
Published: October 2005

The target strengths of marine zooplankton are often predicted from fluid sphere scattering models. These models require estimation of certain physical properties of the individual zooplankters: radius of the equivalent sphere, mass density, and either sound speed or compressibility. This report summarizes previously published measurements of these parameters and recent, unpublished data.
Quantitative analysis of Weddell seal (L
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i) underwater vocalizations at McMurdo Sound, Antarctica
Authors: Thomas Jeanette A. , Kuechle Valerian B.
Published: October 2005

The Weddell seal (Leptonychotes weddelli) has a large repertoire of underwater vocalizations. Twelve underwater calls subdivided into 34 call types were classified based on differences in frequency range, duration, repetition rate, number per series, presence or absence of harmonics, auxiliary sound usage, and contour. The repertoire also contains nine dependent auxiliary sounds. In summary, this study standardizes the description and terminology for underwater vocalizations, reports source sound-pressure levels, and reviews usage differences by male and female seals.
Thickness shear, thickness twist, and flexural vibrations of rectangular AT-cut quartz plates with patch electrodes
Authors: Lee P. C. Y. , Zee C. , Brebbia C. A.
Published: October 2005

The influence of the size and the mass of patch (rectangular electrodes on the vibrations and energy trapping in a plate rectangular crystal plate is studied. Mindlin’s two-dimensional approximate equations of vibrations of crystal plates are employed for which the coupled modes of thickness shear, thickness twist, and flexure are retained. Numerical solutions that satisfy the free-edge conditions of the plate and the continuity conditions of stresses and displacements at the interface of the plated and unplated regions of plate are obtained by the finite element method using displacement formulation. Numerical computations are made for rectangular AT-cut quartz plates with symmetrically placd, patch electrodes. Resonance frequencies and their corresponding two-dimensional modes of vibrations are obtained for various dimensions of plate and electrodes, and for different masses of electrodes. Calculated results are compared with existing analytical results by Mindlin and Lee [Int. J. Solids Structures, 2, 125 (1966)], Lee and Spencer [J. Acoust. Soc. Am. 45, 637 (1969)], and Tiersten [J. Acoust. Soc. Am. 59, 879 (1976)], and experimental data by Curran and Koneval [J. Acoust. Soc. Am. 34, 981 (1967)]. A two-dimensional Bechmann’s number is obtrained which depends essentially on three parameters; the electrode length-to-plate thickness ratio, the electrode wide-to-plate thickness ratio, and the ratio of the mass of electrodes to the mass of the plate per unit area.
Sampling statistics for vibrating rectangular plates
Authors: Waterhouse Richard V. , Kilcullen Arthur F. , Brooks James E.
Published: October 2005

A thin, uniform, rectangular, elastic plate is freely supported in air, and driven so that it vibrates flexurally at a resonance frequency. The modal function, which describes the vibrational displacement over the surface of the plate, is approximated as the product of two sine functions. From this modal function the probability density function (pdf), P(s), for random sampling over the plate surface of the rms acceleration, is calculated to be 4π−2 K(1−s2), where K is a complete elliptic integral. Using this expression and experimental values sampled randomly over the plate surface, estimates of known precision can be made of the mean vibrational level of the plate. Experimental results are given for a steel plate measuring 4 ft×3 ft×1/4 in., resonating at a single frequency; they agree quite well with the theoretical cumulative function derived from the pdf given above. Also considered are cases where two overlapping modes are excited at a given frequency. The corresponding pdfs are found, by Monte Carlo calculations, for five different values of phase difference between two modes excited with equal amplitudes. As the pdfs are known for the case where a pure tone excites many overlapping modes (exponential for the mean-square acceleration, Rayleigh for the rms value), an outline of the sampling statistics is now available for all modal densities.
Surface acoustic wave propagation in a biasing electric field
Authors: Joshi S. G.
Published: October 2005

The influence of a biasing electric field on the propagation of surface acoustic waves in LiNbO3, LiTaO3, and PbTiO3 ceramic substrates is experimentally investigated. The 128° rotated Y-cut, X-propagating orientation of LiNbO3 shows a linear and fairly large variation of time delay with the biasing field. Fractional time delay changes greater than 0.12% have been obtained, and values up to 0.16% appear possible in SAW devices fabricated on this material. These changes in time delay are adequate to make the technique useful for several applications. Possible applications of this effect for beam steering in phased array antennas, measurement of high voltages, temperature compensation in SAW devices, and improving the efficiency of SAW convolvers are discussed.
Solving cochlear mechanics problems with higher-order differential equations
Authors: de Boer E. , van Bienema E.
Published: October 2005

Since most ‘‘exact’’ solution methods for cochlear models are rather unwieldy, they do not lend themselves to easy and multi-purpose application. In this paper a new solution method is described that is more flexible in this respect. A three-dimensional cochlear model is considered. It can be described by an integral equation in terms of the wavenumber k. The kernel Q(k) of that equation is approximated by a rational function of k and this makes it possible to reformulate the problem as a differential equation. The latter can be solved by a straightforward and well-known method. Results of computations with this technique are presented in two forms: an overview of the entire cochlear wave pattern and a detailed representation of the response peak. The method is also used to determine whether a discernible reflected wave is produced in the cochlea or not. For this purpose the wavenumber spectrum of the cochlear wave is studied: It is found to be a one-sided function of k. With surprisingly simple means it is thus shown that no appreciable reflection occurs from the inhomogeneity that is characteristic in cochlear wave propagation. This holds true for values of damping constant (δ) as low as 0.01, a factor of 5 smaller than is commonly used in cochlear modeling.
Multiple reservoir model of neurotransmitter release by a cochlear inner hair cell
Authors: Schwid Howard A. , Geisler C. Daniel
Published: October 2005

A probabilistic model is described for transmitter release from hair cells, auditory neuron EPSP’s, and discharge patterns. The present model assumes that several reservoirs of neurotransmitter exist, having individual probability-of-release functions centered at successively higher intensities. The model accurately mimics the adaptation of successive EPSP amplitudes of the afferent neuron of the goldfish sacculus and, for mammalian auditory-nerve fibers, the adaptation of neural discharge rate, the saturation of onset and steady-state neural rate versus intensity, and the change in neural rate in response to incremental stimuli. The model also produces realistic interval and period histograms. The data shown support the hypothesis that multiple populations of neurotransmitter are involved in the afferent hair-cell synapses.
Inherent relation between the real part and the imaginary part of a complex holographic function in acoustic holographic imaging—Digital reconstruction method without conjugate image by using only the real part (or imaginary part) of a complex holographic function
Authors: Zhang Pao-cheng
Published: October 2005

A method of deriving the imaginary part of a complex holographic function from its real part on the discrete acoustic holographic imaging is given in this paper, and by using the complex holographic function, combining this obtained imaginary part with the original real part, it is possible to reconstruct the image of the object without the conjugate image. The condition of the method is that the size of the object to be imaged must be less than or equal to λz/2d, where λ is the wavelength, d is the interval between sampling points, and z is the distance between the object and receiving plane. By utilizing a computer, simulation is completed, which proves the above method valid.
Intensity perception. XII. Effect of presentation probability on absolute identification
Authors: Chase S. , Bugnacki P. , Braida L. D. , Durlach N. I.
Published: October 2005

Identification experiments using 13 tone-pulse stimuli (1000 Hz, 500 ms) spaced by equal decibel increments from 42 to 90 dB SPL were conducted under three conditions: all intensities equally likely (denoted Q), the middle intensity presented on roughly 1/3 of the trials (M), and each of the extreme intensities presented on roughly 1/5 of the trials (E). Experiments were performed both with and without feedback, and results were analyzed in terms of sensitivity and bias. Similar results were obtained with and without feedback: listeners generally shifted biases in the M and E conditions relative to the Q condition to increase percent-correct scores, but there were only minor changes in sensitivity from condition to condition. However, sensitivities were generally higher and biases more optimal when feedback was available. The results on sensitivity are consistent with those associated with payoff variation [Lippmann et al., J. Acoust. Soc. Am. 59, 129–134 (1976)], but are inconsistent with those reported for presentation probability variation in tone frequency identification [Cuddy et al., J. Exp. Psychol. 100, 218–220 (1973)]. In an auxilliary experiment concerned with tone frequency identification, results consistent with those obtained for intensity, but inconsistent with those reported by Cuddy et al., were obtained.
Visualization of acoustic scattering by elastic cylinders at low k
a
Authors: Maze G. , Ripoche J.
Published: October 2005

Theoretical studies have shown the great importance of circumferential waves in acoustic scattering by infinite elastic cylinders immersed in a fluid. The ‘‘Resonance Isolation and Identification Method’’ (RIIM) has allowed us to separate the resonances produced by circumferential standing waves by recording the free vibrations which are still present for some frequencies after the forced excitation has stopped. In this paper, the problem of acoustic scattering is studied by a stroboscopic Schlieren visualization method at low frequencies (0<ka<30). We attempt to establish that the acoustic beams generated in specific directions, when the cylinder is no longer excited, are actually issuing from the standing wave antinodes.
Multiple scattering of sound by correlated monolayers
Authors: Twersky Victor
Published: October 2005

Earlier results for scattering by random uncorrelated planar distributions, and by doubly periodic planar configurations of relatively arbitrary obstacles, are generalized to pair-correlated nonsymmetrical monolayers. The existing development for parallel cylinders in terms of the Zernike–Prins one-dimensional pair function p(x), is extended to analogous two-dimensional distributions specified by p(R) for aligned impenetrable disks. We obtain the average multiple scattered transmitted and reflected waves, and an energy conserving approximation of the differential scattering cross section per unit area. Simplified forms are developed to facilitate determing p by inverting measured data. Closed form low-frequency results are derived for identical ellipsoids aligned nonsymmetrically to the plane of centers, and the array multipole-coupling processes are discussed in terms of functions of p and their approximations.
Sound pressure distribution about the human head and torso
Authors: Kuhn George F. , Guernsey Richard M.
Published: October 2005

Published and unpublished data on sound pressure distributions about the human head and torso were collected and analyzed. The results of the analysis are presented graphically. The data include measurements on both humans and manikins in both progressive wave and diffuse fields. The results can be used to aid selection of locations for the microphones of noise dosimeters and hearing aids and design of spectrum shaping circuits for these microphones. An appendix discusses procedures for determining whether it is appropriate to assume a progressive wave or diffuse field when these data are applied to actual situations in the field.
A psychophysical evaluation of the dependence of hearing protector attenuation on noise level
Authors: Humes Larry E.
Published: October 2005

The attenuation characteristics of ten commercially available hearing protectors (five muffs and five plugs) were examined for 1/3-octave bands of noise centered at 1000, 2000, 3150, 4000, and 6300 Hz in ten normal-hearing young adults utilizing four psychophysical procedures. One of these procedures, the real-ear attenuation at threshold procedure described in the American standard for the evaluation of hearing protectors, is designed for use at 1/3-octave band noise levels below approximately 50 dB SPL. Three real-ear psychophysical procedures were also developed and evaluated. These procedures were: (1) a reaction-time paradigm; (2) a loudness magnitude-estimation procedure; and (3) a masked bone-conduction threshold technique. Each procedure was designed to evaluate protectors for 1/3-octave bands of noise having levels ranging from approximately 50 to 90 dB SPL. Mean data indicated that: (1) attenuation was linear over the range investigated, although some exceptions to this generalization were apparent; (2) attenuation estimates derived with the reaction-time and magnitude-estimation paradigms were typically less than those obtained with the other two methods; and (3) all attenuation estimates, regardless of procedure, were less than manufacturer’s specifications for the majority of the protectors. Implications for existing standards are discussed.
A free-field equalizer for TDH 39 earphones
Authors: Fastl Hugo , Zwicker Eberhard
Published: October 2005

The free-field response of TDH 39 earphones, mounted in MX 41/AR cushions, is determined by loudness comparisons in an anechoic chamber. Based on these data, a passive equalizing network with two resonances at 720 and 6000 Hz is developed and realized. When used with this free-field equalizer, the earphone TDH 39 produces a free-field equivalent level independent of frequency within ±2.5 dB in the frequency range 100 Hz to 10 kHz. Because of the small differences between TDH 39 and TDH 49 earphones it is expected that the equalizer can also be successfully applied with the TDH 49.
Human laryngeal responses to auditory stimulation
Authors: Sapir Shimon , McClean Michael D. , Larson Charles R.
Published: October 2005

In spite of various claims for the presence and functional significance of brainstem reflexes in phonatory control, very little is known about these reflexes in humans. The present study was aimed at studying auditory-laryngeal reflexes in human subjects during sustained phonation. Fourteen subjects sustained phonation at constant voice pitch and voice intensity while receiving auditory stimulation with clicks of different intensity levels. Electromyographic (EMG) recordings from the cricothyroid muscle were obtained in two of the subjects. The voice signal was transduced with a throat microphone and bandpass filtered to isolate the fundamental frequency (F0). The filtered signal was fed to a frequency meter, which yielded a voltage proportional to F0. This F0 voltage and the rectified EMG were signal averaged relative to the click. Short-latency changes in F0 (50 ms) and in cricothyroid EMG (11 ms) were observed in response to auditory stimulation. The magnitude of the EMG and F0 responses were well correlated with each other and with the intensity of the stimulus. The EMG response did not habituate with repeated stimulation. The neuromuscular origins of the auditory-laryngeal reflexes and their significance to phonatory control are discussed.
Nonlinear vibrations in plates and gongs
Authors: Rossing Thomas D. , Fletcher N. H.
Published: October 2005

The sounds from certain types of gongs show a frequency shift, up or down, as the vibration decays. In order to understand this nonlinear behavior, we have studied the vibrations of a variety of flat and curved plates under varying amounts of radial tension or compression. Flat plates show a nonlinearity of a hardening type (falling frequency), whereas most curved plates show softening behavior (rising frequency). The degree of the nonlinearity appears to be sufficient to explain the observed frequency shift in the gongs studied.
Velocity of ultrasound in binary solutions of polyacrylamide with water
Authors: Haque M. F. , Stumpf F. B.
Published: October 2005

The velocity of ultrasound at a frequency of 25.1 MHz was measured as a function of concentration, temperature, and time in binary solutions of polyacrylamide with water.
Attenuation measurement with sonobuoys
Authors: Stoll Robert D. , Houtz Robert E.
Published: October 2005

Sonobuoy data in a number of shelf areas have yielded travel time curves which are relatively smooth and which result in velocity–depth profiles that are nearly straight lines to depths of several kilometers. Moreover, many of the records contain several multiples of the first refracted arrival which are well separated from the first arrival and free of excessive noise. Such data are ideal for comparing the amplitude of the first arrival and the amplitude at the corresponding point on the multiple at double distance and double time. By taking the ratio of these amplitudes, the effects of geometrical spreading and the angular dependence of the source are removed so that estimates of total attenuation as a function of depth and frequency are much more easily studied. In this paper we present an example of such a study using sonobuoy data from the Sarawak basin which is located in the South China Sea (4 °N–110 °E). Measurements made in the frequency range of 10 to 60 Hz suggest that the logarithmic decrement δ or the quality factor Q are not constants but depend rather strongly on frequency in the diving waves that were studied.
Wind-generated noise modeling
Authors: Wilson James H.
Published: October 2005

The Wilson wind-generated source level densities and the ASTRAL propagation loss model are combined to form a wind-generated noise model. The model treats storms as a geographically distributed source and is capable of modeling both distant and local storm noise. Model estimates are compared with omnidirectional measurements from the northeastern Pacific Ocean at five frequencies and three receiver depths. The results are very good and indicate the necessity of modeling both shipping and wind-generated noise in comparisons with measured data.
The polytropic exponent of gas contained within air bubbles pulsating in a liquid
Authors: Crum Lawrence A.
Published: October 2005

Gas bubbles that are driven into oscillation within a liquid pulsate with amplitudes that are determined largely by the thermodynamic behavior of the gas contained within the bubble. Theoretical approaches to the solution of the motion of the radius of the bubble normally involve the polytropic exponent of the gas. Measurements are presented of this exponent for three different gases and for a wide range of values of the exponent. Comparison with available theories indicates good agreeement between measurements and predictions provided the gas bubble is not driven near one of its harmonic resonances.
Nonlinear oscillations of gas bubbles in liquids: An interpretation of some experimental results
Authors: Crum Lawrence A. , Prosperetti Andrea
Published: October 2005

Measurements are presented in this paper of the pulsation amplitude of an individual air bubble that is levitated in a glycerine–water mixture by a stationary acoustic wave operating at a frequency of 22.2 kHz. Observations of the bubble pulsation for a wide range of bubble sizes demonstrate the existence of the n=2 harmonic resonance (ω≊ω0/2). The available theoretical information on linear and nonlinear bubble oscillations is adapted to apply to the specific experimental conditions. Comparisons made with the theory show excellent agreement between measurements and predictions.
A propagator matrix method for periodically stratified media
Authors: Gilbert Kenneth E.
Published: October 2005

The propagator matrix formalism of F. Gilbert and G. E. Backus is a convenient general method for treating stratified media. In this paper, the Gilbert–Backus formalism is used in conjunction with Sylvester’s matrix theorem to obtain an exact solution for wave propagation in a periodically stratified medium of arbitrary thickness. Explicit expressions are derived for the simple case of a periodically layered fluid. These expressions are used to investigate several interesting limiting cases. Application of the method to the more complicated case of a periodically layered solid is briefly discussed.
Ultrasonic detection of vibrational relaxation of ClCN and BrCN
Authors: Sayer Clifton , Hess Peter
Published: October 2005

A modified Sell-type ultrasonic transducer, utilizing Teflon materials and the hard-anodization process for the aluminum back plates, shows significant improvement in operating characteristics over earlier models. The vibrational self-relaxation times of ClCN ( pτ=29 ns bar) and BrCN ( pτ=15 ns bar) are measured for the first time. The results are discussed in relation to the empirical Lambert–Salter plot for V–R,T energy transfer.
Measurement of the eardrum impedance of human ears
Authors: Hudde Herbert
Published: October 2005

The determination of an acoustical impedance requires measurements of pressure and volume velocity. As no direct method is available for measuring velocity in an ear canal, a technique was developed which is based on pure pressure measurements. The ear canal is used as a measuring tube, the area function of which is also deduced from the pressure measurements. High-frequency measurements in living subjects involve many sources of errors. A criterion for deciding if a good measurement has been made is given. The technique of measurements is described, regarding both the use of probe tube microphones and the computer aided data recording. Finally, the results are presented, and some comments are given. A reliable interpretation of the results seems to be impossible because of lack of our knowledge of the middle ear function at high frequencies.
The acoustic reflex threshold in aging ears
Authors: Silverman Carol Ann , Silman Shlomo , Miller Maurice H.
Published: October 2005

This study investigates the controversy regarding the influence of age on the acoustic reflex threshold for broadband noise, 500-, 1000-, 2000-, and 4000-Hz activators between Jerger et al. [Mono. Contemp. Audiol. 1 (1978)] and Jerger [J. Acoust. Soc. Am. 66 (1979)] on the one hand and Silman [J. Acoust. Soc. Am. 66 (1979)] and others on the other. The acoustic reflex thresholds for broadband noise, 500-, 1000-, 2000-, and 4000-Hz activators were evaluated under two measurement conditions. Seventy-two normal-hearing ears were drawn from 72 subjects ranging in age from 20–69 years. The results revealed that age was correlated with the acoustic reflex threshold for BBN activator but not for any of the tonal activators; the correlation was stronger under the 1-dB than under the 5-dB measurement condition. Also, the mean acoustic reflex thresholds for broadband noise activator were essentially similar to those reported by Jerger et al. (1978) but differed from those obtained in this study under the 1-dB measurement condition.
Additivity of simultaneous masking
Authors: Lutfi Robert A.
Published: October 2005

Simultaneous masking functions (signal level at threshold versus masker level) were obtained for equally intense maskers presented individually and in pairs. The signal was a 2.0-kHz sinusoid. The pairs of maskers were (1) two sinusoids with frequencies 1.9 and 2.1 kHz, (2) two narrow bands of noise (50 Hz wide) centered at 1.9 and 2.1 kHz, (3) two narrow bands of noise (50 Hz wide) centered at 1.8 and 1.9 kHz, and (4) the 1.9-kHz sinusoid combined with the narrow band of noise centered at 2.1 kHz. The pairs of maskers produced anywhere from 10 to 17 dB of masking beyond that predicted from the simple sum of the masking produced by the individual maskers. The amount of this ‘‘additional masking’’ was independent of masker level. Adding a continuous low level background noise reduced the amount of additional masking only slightly (approximately 5 dB). The data are consistent with a model in which the effects of the maskers are summed after undergoing independent compressive transformations.
An analysis of psychophysical tuning curves in normal and pathological ears
Authors: Carney Arlene Earley , Nelson David A.
Published: October 2005

Simultaneous psychophysical tuning curves were obtained from normal-hearing and hearing-impaired listeners, using probe tones that were either at similar sound pressure levels or at similar sensation levels for the two types of listeners. Tuning curves from the hearing-impaired listeners were flat, erratic, broad, and/or inverted, depending upon the frequency region of the probe tone and the frequency characteristics of the hearing loss. Tuning curves from the normal-hearing listeners at low-SPL’s were sharp as expected; tuning curves at high-SPL’s were discontinuous. An analysis of high-SPL tuning curves suggests that tuning curves from normal-hearing listeners reflect low-pass filter characteristics instead of the sharp bandpass filter characteristics seen with low-SPL probe tones. Tuning curves from hearing-impaired listeners at high-SPL probe levels appear to reflect similar low-pass filter characteristics, but with much more gradual high-frequency slopes than in the normal ear. This appeared as abnormal downward spread of masking. Relatively good temporal resolution and broader tuning mechanisms were proposed to explain inverted tuning curves in the hearing-impaired listeners.
Acoustically derived auditory nerve action potential evoked by electrical stimulation: An estimation of the waveform of single unit contribution
Authors: Charlet de Sauvage Renaud , Cazals Yves , Erre Jean-Paul , Aran Jean-Marie
Published: October 2005

An experimental study of the electrical stimulation of the guinea pig cochlea is made using an electrode on the round window for both stimulation and recording. The neural response is separated from the electrical artifact with a masking procedure combined with a low amplification, ‘‘statistical’’ averaging method [Charlet de Sauvage et al., Hear. Res. 2, 343–346 (1980)]. The high electrical impedance required for recording physiological responses implies the use of a current pulse generator. Monitoring of evoked potentials from the auditory cortex provides evidence that the effects of electrical stimulation (and of masking noise) are of auditory origin. The electrically evoked round window response is of very short latency (less than 0.2 ms). There is a response threshold for both electrical stimulus and masking noise. The response amplitude varies monotonically as a function of masking noise or electrical stimulus intensity. Experiments with high-pass noise masking suggest that the electrical stimulus is mainly acting on basal fibers. The response latency and waveform are independent of electrical stimulus intensity, repetition rate, masker level, or spectrum. Little intersubject variation is noted. Our experiments (reciprocal forward masking by electrical and acoustic stimuli) suggest that a direct, instantaneous electrical stimulation of the fibers occurs. We believe that this response to electrical stimulation represents the mean unit response of the auditory nerve fibers. This approach may be useful in the separate study of cochlear and VIIIth nerve functions and in the analysis (deconvolution) of the acoustically evoked compound AP.