bluuebunny/crossref_metadata_2025 huggingface dataset:
Two determinants of localization acuity in the horizontal plane
Authors: Shelton B. R. , Searle C. L.
Published: October 2005

An attempt was made to extend the auditory localization model of Searle, Braida, Davis, and Colburn [J. Acoust. Soc. Am. 60, 1164–1175 (1976)] to regions beyond the frontal horizontal plane. On the basis of two experiments, it appears that the assumption of acuity independent of angle is not valid for these more extensive regions, although the distribution of error magnitude can be accounted for by a span-specific unitary acuity. However, the assertion by the same authors that acuity is partially determined by the angular size of the speaker span was substantiated by direct experimental test. The results confirm the initial suggestion of Searle et al. that a complete account of the sound localization process must include both span and angular dependencies of acuity, and indicate average error to be a promising measurement technique in resolving this particular problem.
Ultrasound velocity in major bovine blood vessel walls
Authors: Shung K. K. , Reid J. M.
Published: October 2005

Data on ultrasound velocity, compressibility, and specific acoustic impedance in bovine aorta, pulmonary artery, vena cava, and myocardium are reported and analyzed based on amounts of structural proteins present in these tissues.
Low-frequency neural and cochlear-microphonic tuning curves in the gerbil
Authors: Schmiedt R. A. , Zwislicki J. J.
Published: October 2005

Average tuning curves of single auditory-nerve fibers are compared with average cochlear-microphonic (CM) tuning curves corrected for electrical filtering of the cochlea. Both the neural and CM data were obtained from Mongolian gerbils (Meriones unguiculatus) with the same acoustic system and similar corrections for middle-ear effects. Under these conditions the CM tuning in the second and third cochlear turns in similar to the tuning of fibers whose characteristic frequencies (CFs) correspond to the CM best frequencies (2.5 and 0.5 kHz). Thus, little sharpening seems to take place for low CF fibers. CM tuning at the most apical electrode position is sharper than expected for frequencies below the best frequency—a result that may be due to the shunting effect of the helicotrema at low frequencies. Previous modeling results have confirmed that apical basilar-membrane tuning may be appreciably affected by the mechanical impedance of the helicotrema. This helicotrema effect may account for the nearly symmetrical shapes of neural tuning curves of low-CF fibers.
Acoustical properties of the National Bureau of Standards anechoic chamber
Authors: Koidan Walter , Hruska Gale R.
Published: October 2005

The acoustical properties of the large anechoic chamber at the National Bureau of Standards were investigated by two methods over the frequency range 40–63 000 Hz. In the first method described, deviations of mean-square sound pressure from an assumed inverse square law were measured as a sound source and microphone were moved apart. Over most of the frequency range, the deviations were found from a least-squares curve-fitting procedure by means of digital-computer processing of the data. The effective acoustic centers of the sources were obtained as a by-product of the procedure. In the second method, the source and microphone were kept at a fixed separation as they were moved together across the chamber, and deviations from the mean value of the sound pressure level were estimated from recordings. The significances of the two methods are discussed with a view towards their application.
Ultrasonic Grüneisen parameter for nonconducting cubic crystals
Authors: Nava R. , Romero J.
Published: October 2005

The effective ultrasonic Grüneisen parameter obtained from room temperature measurements of the attenuation in 12 cubic crystals is compared with calculations for the anisotropic elastic continuum model in terms of second- and third-order elastic constants. The agreement between the calculated values and those derived from the ultrasonic attenuation is in most cases within a factor of 2 provided local equilibrium effects are included in the expression for the attenuation coefficient. The model accounts in general for the anisotropy and polarization dependence of the attenuation and can be used to estimate the magnitude of the sound absorption by acoustic thermal phonons from known elastic and thermal properties. Ultrasonic Grüneisen parameters are smallest for shear waves polarized along <001≳. Crystals with the NaCl structure show a larger and more anisotropic mean anharmonicity than covalent crystals and alkaline earth fluorides.
Influence of Stoneley waves on plane-wave reflection coefficients: Characteristics of bottom reflection loss
Authors: Hawker Kenneth E.
Published: October 2005

This paper considers characteristics of plane-wave reflection loss for a model of the ocean’s sub-bottom consisting of a single inhomogeneous fluid layer (sediment) overlying a semi-infinite solid (basement). It is found by direct computation that, under certain conditions of sediment sound speed gradient, density, and compressional-wave speed ratios and attenuations, a large peak in bottom loss can occur over a narrow range of grazing angles. These angles occur below the shear and compressional wave critical angles; hence, they are not directly related to transport of energy by these wave fields. It is found, however, that the presence of shear waves in the substrate is necessary for such a peak to occur; that is, if the shear-wave speed is set to zero in the substrate, the anomalous loss peak vanishes. Furthermore, these loss peaks are due to absorption rather than the transport of energy to infinity as evidence by the fact that, when all absorptions vanish, so do the anomalous peaks in bottom loss. The decay of pressure amplitude away from the sediment–substrate interface in both directions (for grazing angles in the neighborhood of the loss peak angles) suggests the presence of a surface or interface wave.
Experimental measurements of acoustic scattering by rows of cylindrical obstacles
Authors: Liao Samson , Sachse Wolfgang
Published: October 2005

Experiments were performed in a shallow two-dimensional water tank to determine the effects of diameter, spacing, and material properties on acoustic scattering by rows of cylindrical obstacles. Cylinder diameters ranged from 0.17 to 0.39 times the wavelength, and center-to-center spacings up to 1.2 wavelengths were investigated. In the limit of small spacings, multiple scattering was found to be characteristically similar to sound wave transmission through walls. Analysis of the experimental data indicated that the acoustic properties and microstructure of the scatterers could be distinguished by the transmissivity response of the arrays.
Synthesis of social surveys on noise annoyance
Authors: Schultz Theodore J.
Published: October 2005

Since noise was first recognized as a serious environmental pollutant, a number of social surveys have been conducted in order to assess the magnitude of the problem and to develop suitable noise ratings, such that, from a measurement of certain physical characteristics of community noise, one could reliably predict the community’s subjective response to the noise. Recently, the author has reviewed the data from social surveys concerning the noise of aircraft, street traffic, expressway traffic, and railroads. Going back to the original published data, the various survey noise ratings were translated to day–night average sound level, and an independent judgment was made, where choice was possible, as to which respondents should be counted as ’’highly annoyed.’’ The results of 11 of these surveys show a remarkable consistency. It is proposed that the average of these curves is the best currently available relationship for predicting community annoyance due to transportation noise of all kinds.
Coal slurry diagnostics by ultrasound transmission
Authors: Davis M. C.
Published: October 2005

Several applications of ultrasonic detectors are suggested for monitoring coal water slurries in coal conversion processes. These include mass flow, particle size, and temperature. Modeling of transmission losses include viscous and thermal transport processes as well as multiscattering effects. Simple monitoring of sound attenuation versus frequency yields a unique dependence from which the value of characteristic parameters may be deduced, all from a single transmitter–receiver pair.
Comprehensive compilation of empirical ultrasonic properties of mammalian tissues
Authors: Goss S. A. , Johnston R. L. , Dunn F.
Published: October 2005

A detailed review of the literature on ultrasonic propagation properties of mammalian tissues and organs has revealed 144 papers containing compilable data. Over 1300 lines of parametric data are listed, including the tissue, species, age, specimen preparation, anatomical structure, pathology, temperature, measurement method, frequency, velocity, attenuation, acoustic impedance, and density.
Model study of Zwicker’s ’’masking period patterns’’
Authors: Hall J. L.
Published: October 2005

Zwicker has demonstrated that the threshold for a high-frequency test-tone burst in the presence of a continuous low-frequency masking tone is a complicated function of the frequency and intensity of the masker and the phase of the masker at which the test tone is presented. ’’Masking period patterns’’ measured for these stimuli show nonlinear effects in that at high masker levels the threshold of test-tone bursts reaches local maxima at two different phases of the masker. We have investigated the implications of these psychophysical data on a computational model for motion of the basilar membrane. The model consists of a nonlinear mechanical system followed by an additional stage of frequency selectivity (’’second filter’’). The output of the model is applied as input to a threshold-level detector. With this model it is possible to reproduce the effects Zwicker observed. Masking period patterns are interpreted as a mnifestation of two-tone suppression. On the basis of our computer simulation of Zwicker’s psychophysical data, we make the following specific predictions concerning the nature of mechanical to neural transduction at the auditory periphery: (1) Membrane motion in one direction produces a nonlinear increase in the loss term, while membrane motion in the other direction does not. (2) The direction of membrane motion that produces increased loss is also the direction of motion that produces neural excitation. (3) There is a stage of sharpening, a ’’second filter,’’ between membrane motion and the neural excitatory signal.
Model for the frequency spread of backscattered underwater sound based on the facet model of the rough sea surface
Authors: Schwarze Herward
Published: October 2005

A theoretical model for the Doppler spread of backscattered acoustic waves from the rough sea surface is described on the basis of the decomposition of the continuous sea-surface spectrum that leads to the concept of facets. The facet statistics are derived for a Gaussian sea surface. The results are evaluated for a Pierson–Moskowitz spectrum. A procedure for choosing the facet length is developed. Approximate, simple formulas for the Pierson–Moskowitz case are given. The general result for the Doppler spread of the backscattered acoustic wave is evaluated for sea-surface spectrum due to Scott, and examples for Doppler spectra are given for different windspeeds, wind directions, grazing angles, and acoustic frequencies.
Scattering function for multiple-bounce underwater acoustic channels
Authors: Tuteur Franz B. , McDonald John F.
Published: October 2005

The second statistical moment of a scattering channel involving several statistically independent bounces is computed, using the Fresnel-corrected Helmholtz integral formulation. The surface at all bounces is assumed to have a Gaussian probability density, and the surface correlation function is taken to be a cosine with a Gaussian envelope. The resulting second-moment function depends primarily on two reverberation time constants. One of these is shown to be simply the sum of reverberation time constants obtained for single bounces. The scattering function is also computed, and it is shown that the multiple bounces can destroy the narrow horseshoe shape of the scattering function found in earlier work on a single-bounce scatter channels.
Long-distance focusing of Concorde sonic boom
Authors: Liszka Ludwik
Published: October 2005

Infra-acoustic signals from supersonic flights of Concorde are regularly recorded in northern Sweden at distances up to 5000 km from the aircraft. Relatively high signal amplitudes (up to 0.1 N/m2) are explained by a kind of long-distance focusing effect. Principle and consequences of the focusing effect are discussed.
Acoustic wave mixing in piezoelectric crystals
Authors: Nelson D. F.
Published: October 2005

A compact expression describing the mixing of two input acoustic waves to produce a sum frequency (including second harmonic) or difference frequency output is derived. It applies to crystals of any symmetry (dielectrics, piezoelectrics, and pyroelectrics) and to acoustic waves of any types (pure or hybrid modes) propagating collinearly or noncollinearly in any directions (consistent with being close to or at phase matching). The material interaction coefficient that governs the mixing process is obtained in general form; it differs from previously published forms.
Vibration of the uniform spinning cable with tip mass
Authors: Vance O. L. , Katholi C. R.
Published: October 2005

This paper presents analyses of both in-plane and out-of-plane free vibrations of a uniform cable with tip mass attached to a disk turning at constant rate about a fixed axis. Included in the analyses is the development of small-argument asymptotic approximations for the Legendre functions of the first and second kinds.
Measurement of ultrasonic dispersion by phase comparison of continuous harmonic waves
Authors: Ting C. S. , Sachse Wolfgang
Published: October 2005

The method of phase comparison of continuous waves is applied to determine the dispersion relation, phase, and group velocities as a function of frequency of dispersive materials. A combination of the variable frequency method and the variable path-length method is found necessary to eliminate any uncertainty in the dispersion relation determination. Experiments are performed on specimens of various thickness. A constraint equation can be derived since the dispersion relation is unique and independent of the specimen thickness. This equation provides a procedure for determining the absolute number of wavelengths in the specimen. Measurements in unidirectional, fiber-reinforced boron–epoxy specimens show good agreement with results reported previously.
Properties of a movable-gate–field-effect structure as an electromechanical sensor
Authors: Yoshikawa Akira , Suzuki Toshimasa
Published: October 2005

In order to examine the applicability to electromechanical transducers, fundamental characteristics of an MOS field-effect structure with a movable gate electrode, or a ’’movable-gate–air-gap–oxide–semiconductor’’ system, are investigated. In this system, a channel current suffers field-effect modulations by a mechanical displacement of a gate electrode. As a movable-gate electrode, a metal plate, and a foil electret are used. Equations derived from an approximate treatment of MOS–FET equations are found to explain the experimental results. Based on these equations and experimental facts, design considerations for electromechanical transducers using this structure are made. As an example of applications, microphones utilizing foil electrets are constructed and their performances are discussed.
Acoustic impedance variations at burn–nonburn interfaces in porcine skin
Authors: Cantrell John H. , Goans Ronald E. , Roswell Roberta L.
Published: October 2005

The success of the ultrasonic pulse-echo technique for measurement of the depth of burn necrosis in porcine skin [Med. Phys. 4, 259–263 (1977)] has led to the present investigation of the specific acoustic impedance difference between the necrotic (burn) tissue and the underlying viable (nonburn) tissue. Experimental results show that the ultrasonic group velocities and mass densities are approximately the same in these tissues yielding average values of (1.72±0.12) ×105 cm/s for group velocity and (1.093×0.009) g/cm3 for the density. The characteristic impedance (density times velocity) differs by at most 3% between necrotic and viable tissues. Measurements of acoustic attenuation show a difference of approximately 70% between these tissues. porcine skin is due primarily to the difference in acoustic attenuation.
Temporal summation of constant and gliding tones at masked auditory threshold
Authors: Náb?lek Igor V.
Published: October 2005

Masked thresholds for constant and gliding tones were determined by the method of adjustment for durations between 0.5 and 5000 ms in three overlapping frequency regions between 0.25 and 3.3 kHz. The masker was a continuous white noise at 70-dB SPL. Listening was monaural; subjects had normal hearing. Below 10 ms the thresholds for upward glides were lower and those for downward glides higher than the thresholds for constant tones. In the 10–300-ms duration range, which encompasses formant transitions of speech, the highest thresholds are for downward glides and the lowest ones for constant tones. These differences could result from different time courses of neural decay and inhibition for constant tones, upward and downward glides. The differences between upward and downward glides indicate that the phase spectra influence sound detectability. The thresholds for constant tones reach minimum around 1 s. The thresholds for glides continue to decrease at least up to 5 s. The ’’critical’’ duration for constant tone integration can result from the overriding of integration effects by adaptation effects, the latter ones being eliminated by changing frequency. The curves for constant-tone threshold between 10- and 1000-ms duration were fitted by a product of exponential and hyperbolic functions.
On the role of spatial and temporal cues in the perception of the pitch of complex tones
Authors: Ohgushi Kengo
Published: October 2005

This paper describes a new approach to pitch perception. It focuses attention on the slight difference between the pitch of complex tone and the pitch of a pure tone with the same (fundamental) frequency. This approach is based on the assumption that pitch perception is based on both spatial and temporal cue analysis. In this study, the values provided by the temporal cue are calculated from physiological data from the auditory nerve fibers. The possible ratios of the pitch of complex tones relative to the pitch of pure tones at various frequencies are predicted. Psychophysical experimental results strongly support this prediction. In addition, another experiment suggests that the above psychophysical effect is not based upon a mutual masking effect in the spatial domain.
Adaptation of the acoustic reflex
Authors: Wilson Richard H. , Steckler Jane F. , Jones Howard C. , Margolis Robert H.
Published: October 2005

The characteristics of acoustic reflex adaptation were studied in human subjects. Contralateral stapedial reflex measurements were made by monitoring changes in acoustic conductance and susceptance with a 220-Hz probe. The reflex activators included four tonal stimuli (500, 1000, 2000, and 4000 Hz) and broadband noise presented for 180 s at 96, 104, and 112 dB SPL. The data are presented as change in acoustic admittance and in percent of maximum admittance change. The static admittance of the ear was found to drift systematically toward lower admittance values in the absence of contralateral stimulation. All stimulus conditions demonstrated some reflex adaptation. The half-life and time of onset of adaptation were found to vary directly with intensity and inversely with frequency. The effects of stimulus parameters on the rates of reflex adaptation are discussed. A previously described exponential model of reflex adaptation provided a reasonable first approximation to the data.
The consistency of the pressure-flow technique for assessing oral port size
Authors: Smith H. Zack , Allen George , Warren Donald W. , Hall David J.
Published: October 2005

The consistency of the technique for estimating oral constriction size was studied under a variety of conditions including varying the subjects’ preparation for a task, varying the testing procedure, and changing phonetic context. Results indicate that both the mean and variance of oral port openings for the phonemes /s/, /f/, /v/, and /z/ differ among subjects but are fairly consistent within individuals. The consonants differed in terms of mean oral port size according to phonetic type, with /s/≳/f/≳/z/≳/v/: voiceless sounds demonstrated larger openings than voiced sounds, and alveolars larger than labiodentals. Oral port openings were also smaller in continuous speech than in isolated sounds. Changing the subjects’ preparation for the task of varying the procedures affected neither the average size of the opening nor its variability.
Vibrational relaxation effects on the atmospheric attenuation and rise times of explosion waves
Authors: Bass H. E. , Raspet Richard
Published: October 2005

The effect of vibrational relaxation processes on the rise times and overpressure decay of weak shock waves from explosions is investigated. Calculations have been performed which incorporate finite amplitude wave effects, spherical spreading, classical acoustic attenuation, and attenuation due to vibrational relaxation of oxygen and nitrogen. These calculations are compared to data and to the results of an empirically based calculation.
Acoustic impedance measurement using sine sweep excitation and known volume velocity technique
Authors: Singh Rajendra , Schary Michael
Published: October 2005

The direct determination of acoustic impedance requires the measurements of both pressure and volume velocity, but the latter in general cannot be measured directly. Thus, other means must be adopted to bypass this measurement problem. This paper presents two methods which utilize excitation of a system with known volume velocity. This, along with measured pressure response, provides both magnitude and phase of impedance as continuous functions of frequency. The first method uses a convertible acoustic horn driver for excitation. Its volume velocity is determined by measuring calibrated pressure in a fixed cavity at the back of the driver. The second method uses for excitation an electrodynamic shaker driven piston which carriers an accelerometer. This signal is integrated to yield input acoustic velocity information. The two-channel analog signal processing setup includes the following instruments: sine sweep oscillator, tracking filters, log converters, phase meter, etc. In order to establish the validity of the proposed experimental techniques, several example cases have been evaluated. Excellent agreement between theory and measurements are obtained for driving point and transfer impedances over the plane wave frequency regime. The advantages of the methods proposed here over some other established techniques are as follows: (1) our methods are easier to use, (2) continuous impedance spectra are obtained quickly, (3) excellent dynamic range is achieved, and (4) complications of digital systems are not involved.
Loudness of complex sounds as a function of the standard stimulus and the number of components
Authors: Florentine Mary , Buus So/ren , Bonding Per
Published: October 2005

The purpose of this study was twofold: to determine if the measured loudness level of a signal depends on the standard stimulus used and to measure loudness as a function of the number of components in a wide-band signal. The stimuli were a pure tone, tone complexes with frequency separations of 231 and 1592 Hz, and noise bands with widths of 220 and 1592 Hz. The center frequency was 1 kHz and the loudness level was approximately 65 phons. Loudness matches between all combinations of stimuli showed that the measured loudness of the sounds did not depend on the standard stimulus used and the measured loudness level of a wide-band sound increased as a function of the number of components. Individual observers were consistent in their loudness estimations; the greatest source of variability was among subjects. Additional measurements indicated that the rate at which loudness increased beyond the critical band appeared to be greater for noise bands than for two-tone complexes.
Application of the Fourier series method to the detecton and localization of signals embedded in a noise background
Authors: Wilson J. H.
Published: October 2005

A Fourier series technique to enhance signal-to-noise ratio and to estimate the azimuth of signals embedded in a noise background is developed in this paper. The method uses beam measurements made by horizontal line array as inputs. Currently, the average value of incoming energy across a given beam is utilized directly or empirically to estimate the arrival intensity and azimuth. Dividing the beam energy by the beamwidth produces an estimate that is the average of signal times array beam pattern function. The average value of energy from a single source is considerably lower than the corresponding peak value. Also, the azimuth of an incoming signal of interest must be estimated empirically from average intensity levels at adjacent beam centers. The primary objective of this analysis is to provide an estimate of peak values (rather than average values) of the acoustic energy at all azimuths by applying the Fourier series method to utilize the full beam pattern of the array. In the method described in this paper, the acoustic field is expanded in a Fourier series and Fourier coefficients are determined from beam intensity measurements. The method provides a best estimation of the signal plus noise field from beam measurements of a line array system, since the Fourier series is a trigonometric polynomial with the smallest mean square difference from the actual horizontal noise field. The major conclusion of this analysis is that signal-to-noise ratio and estimation of the azimuth of distant signals measured by line array systems are enhanced when the Fourier series method is applied to beam measurements. Enhancement results in the improved prediction of (1) signal arrival azimuth and (2) peak signal level. These conclusions are based on application of the Fourier series method to a limited number of mathematical models of acoustic fields; further evaluation of the Fourier series method for a greater variety of mathematical model acoustic fields is necessary to further quantify the results.
Effect of intermittent truck noise on percentage of deep sleep
Authors: Thiessen G. J. , Lapointe A. C.
Published: October 2005

Sleep was divided into only two categories, ’’deep’’ and ’’shallow,’’ the latter including waking, stage 1, and dreaming. For the sake of objectivity and precision the criterion was the level of alpha frequency and/or the audibility of spindles (from a speeded up tape recording of the EEG signals from frontal electrodes), which were timed by stopwatch. Twenty truck noises, presented every other night at peak levels of 65 dB (A-weighted), reduced deep sleep of 12, mainly young subjects by an average of 3%. Adaptation of the waking response occurs despite the separation of the noise nights by at least one quiet night. Adaptation to sleeping in the laboratory appears to continue for more than the one or two nights usually assumed.
Fourier transform recording and playback system
Authors: Hannum L. A.
Published: October 2005

The sequence of finite-range Fourier integrals of an audio program (the series coefficients) represents a nonanalog recording of the program, and the summation of these in the Fourier series represents a continuously repeating playback of the recording. An electronic system for implementing the process is now within reach as a result of microelectronic advances. The nonanalog character of the recording leads to some surprising results in circuit operation, the most interesting being the absence of moving parts in any form during recording or playback. The most difficult design problems would appear to be component generator phase control and integrator output stabilizing.
On scattering from a moving rough surface without a Kirchhoff or a farfield approximation
Authors: Kuperman W. A.
Published: October 2005

Previous surface scattering results are modified to include surface motion. The spectral distribution of the scattered field is derived and the generation of Doppler-shifted surface waves is shown to be related to the form of the specular-reflection coefficient. Modification to previous results for the normal mode attenuation coefficients of a rough waveguide are also presented.
Propagation and decay of waves in porous media
Authors: Mengi Yalcin , McNiven Hugh D.
Published: October 2005

A study is made of the propagation of wave fronts in two types of fluid-filled porous media, anisotropic and isotropic. The characteristic equation governing wave propagation velocities in anisotropic media is obtained by using the notion of surfaces of discontinuity. It is found that the wave velocities in such media vary with the direction of propagation and that for a specified direction there are four different wave velocities with which the disturbances can propagate. When the material is isotropic, its frequency equation shows the existence of three distinct waves, two longitudinal waves and one shear wave with velocities independent of the direction of propagation. The decay equations derived for these waves indicate that there are two factors which influence the decay of waves in isotropic porous media. The first is the geometry of the wave front, and the second is the friction between the solid and fluid phases.
Acoustical reflections from aluminum cylindrical shells immersed in water
Authors: Ryan William Wade
Published: October 2005

The purpose of this study was to examine and compare theoretical and experimental steady-state response functions for two thin aluminum cylindrical shells immersed in a water medium. Theoretical steady-state response functions are presented for air-filled and water-filled cylinders of infinite extent for the nondimensional frequency (ka) ranges from near 0 to 52. Experimental measurements are shown for the air-filled cylinders of finite length. Two sets of circumferential waves which are analytically derived from the steady-state response functions are also described and compared with photographs of the corresponding experimental echoes. Good agreement between calculated and measured values is demonstrated.
Measurements of the frequency dependence of normal modes
Authors: Tindle C. T. , Guthrie K. M. , Bold G. E. J. , Johns M. D. , Jones D. , Dixon K. O. , Birdsall T. G.
Published: October 2005

An experiment using a vertical array to detect acoustic normal modes in shallow water is described. A high signal-to-noise ratio was achieved by the use of pseudorandom pulse sequences to modulate the projector. Wide bandwidth signals and a tunable acoustic source enabled the frequency dependence of normal modes to be measured and results are in good agreement with the theory. An improved method of extracting the signal present in a single mode is described and used to examine pulse shapes and frequency spectra of individual modes.
Numerical investigation of nonlinear mode coupling of elastic waves
Authors: Sugimoto Nobumasa
Published: October 2005

Initial value problems are solved numerically for the equations proposed in a previous paper for describing the nonlinear mode coupling of elastic waves. It is conjectured that the mode coupling observed would arise as a result of nonlinear interactions between the main pulse and disturbance. To confirm this conjecture, we choose such typical and simple initial conditions that the main pulse is given by a Gaussian distribution function, while the disturbance is by a small monochromatic wave. It is shown that the results of numerical analysis correspond qualitatively to the main experimental features, i.e., reduction of the peak amplitude of the main pulse and formation of the beat patterns. Thus it is verified that these coupling equations can give, at least qualitatively, an appropriate description for the mode coupling. Some analytical properties of the coupling equations are also discussed. They always have monochromatic wave solutions with constant amplitudes. For a special case, the coupling equations are shown to be reduced to solvable equations subject to arbitrary initial conditions. It is further demonstrated numerically that the mode conversion predicted in the previous paper is possible.
Psychophysical pitch biases related to vowel quality, intensity difference, and sequential order
Authors: Chuang Chiu-Kuang , Wang William S-Y.
Published: October 2005

This study investigates two types of psychophysical pitch bias, one related to vowel acoustical characteristics and the other to sequential order. Based on the analysis of the variation of the subjective equality of pitch in subjects’ responses, a multivariate interaction model is used to explain the experimental results and also to demonstrate the existence of the two types of psychophysical pitch bias. The first pitch bias related to a vowel acoustical characteristic is due to the vowel quality difference as a pitch difference at equal fundamental frequency. By using / / as a common reference, this bias for three test vowels /e, i, u/ is found to be lower than / / by values of 0.54 1.25, and 2.80 Hz, respectively. The other pitch bias related to acoustical characteristic is due to the vowel intensity difference. With intensity difference ranges from 0 to 30 dB, the pitch shift (bias) does not exceed 0.2 Hz at a test F0 of 100 Hz. Apparently, an intensity difference produces insignificant pitch shift in vowel sounds. The pitch bias related to the sequential order of stimuli presentation is a −0.33-Hz bias, i.e., a trend of overestimating the pitch of the second sound in temporal pitch comparison. The pitch discriminability, i.e., the just noticeable difference (JND) at 75% threshold, in an environment with three acoustical parameters varing simultaneously is found to be 1.5%, about three times greater than the previously reported 0.5% DL when F0 varies alone. Finally, the psychophysical bias of vowel is also found to depend upon the power spectrum and negatively correlated to the magnitude of the F0 production discrepancies of the average vowel sounds.
Bottom reverberation measurements at low grazing angles in the NE Atlantic and Mediterranean Sea
Authors: Smailes I. C.
Published: October 2005

Measurements of the levels of bottom scattering strength have been made at a frequency of 2 kHz for grazing angles between 5° and 40° in the NE Atlantic and Mediterranean and lie in the range from −16 to −35 dB. The scattering strength was observed to rise with grazing angle from 5° to 30° and fall again from 30° to 40°. A simple model was fitted to the data which explained the peak at 30° in terms of the Rayleigh reflection coefficient and also enabled an estimate of the rms bottom slope to be obtained. High levels of backscatter were found in Abyssal Plains together with low rms bottom slopes, whereas rougher areas exhibited lower scattering strengths, higher rms bottom slopes and less variation of scattering strength with grazing angle. The absorption of energy into the sea bed has been put forward as a possible explanation for this relationship.
Physical model studies of forward surface scatter frequency spreading
Authors: Zornig John G.
Published: October 2005

An experimental study of frequency spreading in acoustic signals forward scattered from model-tank wind-driven water surfaces has been performed. The study employed wide band probing signals to doubly sample the surface-scatter process. A high degree of precision and demonstrated repeatability was produced. Parameters varied in the study included grazing angle, surface roughness, wind direction, and acoustic wavelength. Rayleigh roughness parameters varying from 0.7 to 12 were studied. The results of the study consist of a large number of measured frequency spreading functions and an analysis of the frequency shift of the mean scattered power and rms spread as a function of wavelength for each condition of wind and grazing angle. This analysis indicates qualitative agreement with current theory in the general form of the spread spectrum at high and low roughness, and in the linear dependence of the mean shift on frequency. However, the data showed a marked sideband asymmetry in symmetric geometric configurations, which is not consistent with any published analytical model. In addition, at short wavelengths, frequency spread seemed not always to increase linearly with carrier frequency.
Extensions of some identities in elastodynamics with rigid inclusions
Authors: Mei Chiang C.
Published: October 2005

For a rigid body of arbitrary shape in elastic waves, symmetry of the restoring forces and the positiveness of the damping matrix are shown. Identities relating to elastodynamic states are derived for infinite and half-plane problems. In addition to the customary combinations of two diffraction states, mixed combinations of diffraction and radiation states are also considered.
Temporal integration of two-component tone glides
Authors: Cullen John K. , Collins M. Jane
Published: October 2005

Temporal integration of complex signals composed of two linearly combined tone glides was studied in a 60-dB SPL noise background. When both glide tones increased or decreased in frequency, integration functions differed for durations shorter than 50 ms in a manner similar to results obtained for single-component tone glides. That is, rising two-component glides were detected at lower thresholds than were falling two-component glides. However, when one component increased in frequency and the other decreased, thresholds were the same, regardless of which component increased and which decreased.
Identification of the minimum level of noise capable of producing an asymptotic temporary threshold shift
Authors: Stephenson M. R. , Nixon C. W. , Johnson D. L.
Published: October 2005

JASMA,63,S65,1978
Point source transmission through a sinusoidal ocean surface
Authors: Meecham William C.
Published: October 2005

The problem of point source transmission through a sinusoidal ocean surface is considered. There are three basic approximations used. (1) The sound wavelength in air should be much less than the radius of curvature of the sinusoidal surface. (2) The maximum surface slope of the sinusoidal surface should be small. (3) The source and receiver distances should be very much greater than k1ζ02 where k1 is the wave numer in air and ζ0 is the amplitude of the ocean surface. This last restriction leads to the useful result that the phase dependence of the field upon ζ is linear. The result of the theory presented here is that in most cases there is relatively little change in the intensity of the field for the sinusoidal surface from that experienced for a flat surface. However, there are changes of several decibels which can be experienced primarily as a result of coherence between the various diffracted components being transmitted into the water region. A novel aspect is that there can be sound transmission for the sinusoidal surface from regions where the flat surface sould totally reflect.
Identification of deleted consonants
Authors: Pols L. C. W. , Schouten M. E. H.
Published: October 2005

VC transitions have often been found to be better cues for the identification of deleted consonants than CV transitions. The lower score for CV transitions could very well be due to an interfering ’’click sensation’’ caused by the abrupt begining of these transitions. In the present investigation the abrubt onset was eliminated by replacing the deleted portions of the consonants with noise bursts; this also caused the incomplete syllables to sound more natural. The results show that the identification of deleted initial voiceless plosives is greatly improved by the addition of noise. The original difference between initial and final plosive transitions disappears almost completely.
Selective anchoring and adaptation of phonetic and nonphonetic continua
Authors: Simon Helen J. , Studdert-Kennedy Michael
Published: October 2005

A series of four experiments compared the effects of unequal probability anchoring and selective adaptation on phonetic and nonphonetic judgments. The basic stimulus series was a synthetic stop consonant continuum ranging from /b/ to /d/. On this continuum were superimposed covariations in fundamental frequency, intensity or vowel. In each experiment subjects listened to identical test tapes under two judgment conditions: place of articulation, and pitch or loudness or vowel judgments. The two types of judgment were significantly dissociated under both anchoring and adaptation paradigms, thus demonstrating that the former may be no less selective than the latter. From this and other evidence, it was concluded that the two paradigms are, in principle, equivalent, and that the main factors in speech adaptation effects are peripheral fatigue and central auditory contrast. If the selective processes of fatigue and contrast are taken to reflect functional channels of analysis rather than the operation of feature detectors, the same broad processes can be seen at work in both speech and nonspeech adaptation.
Invariant cues for place of articulation in stop consonants
Authors: Stevens K. N. , Blumstein S. E.
Published: October 2005

In a series of experiments, identification responses for place of articulation were obtained for synthetic stop consonants in consonant–vowel syllables with different vowels. The acoustic attributes of the consonants were systematically manipulated, the selection of stimulus characteristics being guided in part by theoretical considerations concerning the expected properties of the sound generated in the vocal tract as place of articulation is varied. Several stimulus series were generated with and without noise bursts at the onset, and with and without formant transitions following consonantal release. Stimuli with transitions only, and with bursts plus transitions, were consistently classified according to place of articulation, whereas stimuli with bursts only and no transitions were not consistently identified. The acoustic attributes of the stimuli were examined to determine whether invariant properties characterized each place of atriculation independent of vowel context. It was determined that the gross shape of the spectrum sampled at the consonantal release showed a distinctive shape for each place of articulation: a prominent midfrequency spectral peak for velars, a diffuse-rising spectrum for alveolars, and a diffuse-falling spectrum for labials. These attributes are evident for stimuli containing transitions only, but are enhanced by the presence of noise bursts at the onset.
Effect of sensorineural hearing loss on acoustic stapedius reflex growth functions
Authors: Silman Shlomo , Popelka Gerald R. , Gelfand Stanley A.
Published: October 2005

The growth function of the acoustic stapedius reflex was measured in subjects with normal hearing and sensorineural hearing loss of cochlear origin. The effects of age and magnitude of hearing loss were controlled. Activating stimuli were 500, 1000, and 2000 Hz tones and broadband noise. Stapedius muscle activity was inferred from acoustic impedance measures in the contralateral ear. The mean growth functions for tones were essentially linear in log–log plots with the rate of growth equal for the two groups. The mean growth function for the noise signal was curvilinear for the normal hearing group and linear for the hearing loss group. Comparison of slope functions derived from the fitted data indicated that the rate of reflex growth for the noise signal, over a limited range above reflex threshold, is greater in ears with cochlear lesions than normal ears. For higher level noise signals, however, the rate of reflex growth is similar for normal and pathological ears. The effect of a cochlear lesion on the input–output function of the cochlea for both tonal and noise stimuli is to maintain the rate of reflex growth but shift the function along the intensity axis of a tonal signal and the response axis for a noise signal.
Array shading for a broadband constant directivity transducer
Authors: Jarzynski J. , Trott W. James
Published: October 2005

The theory of a broadband constant directivity transducer is developed. The transducer is an array of isophase, omnidirectional elements on an acoustically transparent spherical surface. It is shown that, with appropriate amplitude shading of the array elements, the beam pattern has no side lobes and the directivity is constant at all frequencies above a cutoff frequency (determined by the beam width and the radius of the sphere.) A shading function is derived, which consists of a simple linear combination of powers of cos ϑ, and several beam patterns are calculated.
Theoretical response of condenser microphones
Authors: Zuckerwar Allan J.
Published: October 2005

Modifications to prior theory yield expressions for the frequency response and equivalent lumped elements of a condenser microphone in terms of its fundamental geometrical and material properties. Results of the analysis show excellent agreement with experimental data taken on B&K pressure microphone types 4134 and 4146.
Rapid withdrawal from a sound source by open-ocean sharks
Authors: Myrberg Arthur A. , Gordon Charles R. , Klimley A. Peter
Published: October 2005

Studies undertaken in the Straits of Florida and the Tongue of the Ocean (TOTO), Bahamas, have established that silky sharks, Carcharhinus falciformis, while approaching a source of underwater sound, will withdraw rapidly from its vicinity if specified changes occur in the nature of the transmitted sound. These changes include: 1) an increase in level of the sound being transmitted (approximately 20 dB) and 2) an abruptness by which that level is achieved. Augmenting factors may include sudden changes in the spectral or temporal qualities of the transmitted sound. Although a biological sound (killer whale scream) could elicit clear withdrawal, it possessed no unique quality; rather, more simply constructed sounds, possessing only a restricted band of frequencies and lacking frequency-modulation, were equally effective. Habituation of the response was apparent during successive tests. All results closely followed those obtained on lemon sharks, Negaprion brevirostris, during a concurrent study (to be reported elsewhere). In the presence of added stimulants (chopped, fresh fish) withdrawal could be elicited in small silky sharks for only a short time. Limited testing of oceanic whitetip sharks,Carcharhinus longimanus, showed that extremely limited withdrawal could also be elicited in that species.
Longitudinal pulse propagation characteristics in striated muscle
Authors: Truong Xuan T. , Jarrett Steven R. , Rippel Diana V.
Published: October 2005

The real part of the complex Young’s modulus of whole frog sartorius muscle in the resting state was derived from step pulse propagation data in the frequency range of 1.0–10 000 Hz. The derivation was based on Fourier integral analysis of the shapes of the propagated pulses to obtain velocities and attenuation coefficients for various harmonic frequencies. The results were consistent with previous sinusoidal wave propagation studies in the higher-frequency range. The general frequency response of the muscle was analogous to the ’’standard linear solid’’ model. The relaxation time spectrum derived from the modulus–frequency function showed similar spectral contents to spectra obtained with other methods. The advantages and limitations of the pulse method are discussed.