bluuebunny/crossref_metadata_2025_split huggingface dataset:
Two-tone unmasking and suppression in a forward-masking situation
Authors: Shannon Robert V. 
Published: October 2005

A forward-masking situation was investigated where more energy added to the masker decreased the threshold of the signal. The signal was a single sinusoid. The masker contained two frequency components: one at the same frequency as the signal, and one at a variable frequency. For certain frequencies and intensities of this variable masker component the threshold of the signal was lower than if that component were not present.This decrease in threshold is unmasking. Unmasking is interpreted as being caused by the suppression of the fixed masker component by the variable masker component, thus producing less masking at the signal frequency. The basic pattern of masking and ummasking was qualitatively similar to the pattern of pulsation thresholds observed by Houtgast [Acustica 29, 168-179 (1973). Unmasking was not observed at absolute threshold or in a simultaneous masking situation. Unmasking was observed at all signal frequencies tested (0.5–6.0 kHz) and was not dependent on the phase of the masker components or the phase between the masker and the signal. When the frequency of the variable masker component was less than the signal frequency, unmasking was dependent on only the intensity of the variable component. However, when the variable frequency was greater than the signal frequency, unmasking was dependent on the difference in intensity between the two masker components. The existence of unmasking in a forward-masking situation does not depend on whether or not the masker and signal are turned on and off abruptly or smoothly. These characteristics of unmasking are not in conflict with the assumption that this effect is caused by the variable masker component suppressing the other masker component.
Subject Classification: [43]65.58, [43]65.68, [43]65.50.
Ultrasonic bounded beam reflection and transmission effects at a liquid/ solid-plate/liquid interface
Authors: Plona Thomas J. , Pitts Leslie E. , Mayer Walter G. 
Published: October 2005

Schlieren techniques are used to show that bounded beam reflection effects occur at liquid/solid-plate/liquid (L/SP/L) interfaces which are analogous to the bounded beam reflection effects reported previously at liquid/solid (L/S) interfaces. At L/SP/L interfaces, nongeometric effects are shown to be present in both the reflected and transmitted beams when the incident angle of an ultrasonic beam corresponds to the Lamb angle. In addition, similarities between wave phenomena at L/SP/L interfaces and L/S interfaces are presented which suggest that the description of bounded beam reflection derived by Bertoni and Tamir for a L/S interface can be qualitatively applied to the L/SP/L interface case. This theory is shown to account for the lateral extent to which a leaky Lamb surface wave, excited by mode conversion, propagates.
Subject Classification: [43]35.54; [43]20.40, [43]20.30.
Direct image reconstruction of anomalies in a plane via physical optics farfield inverse scattering
Authors: Bleistein Norman 
Published: October 2005

This paper shows how to process backscattered acoustic data to directly generate the image of an anomaly in a plane such as an anticline, syncline, or fault. The result is based on a physical optics farfield inverse scattering (POFFIS) identity. This identity states that a phase- and range-normalized scattering amplitude is proportional to a function which is unity in the region of the anomaly and zero outside that region.
Subject Classification: [43]20.30, [43]20.15; [43]40.50.
Temporal auditory summation for pure tones and white noise in the house mouse (M
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Authors: Ehret Günter 
Published: October 2005

The dependence of the absolute auditory threshold on signal duration was measured by means of behavioral methods in the house mouse (Mus musculus). Twelve frequencies between 1 kHz and 120 kHz and white broad-band noise were tested while seven pulse durations between 1 and 3000 msec were used. In any case temporal summation follows the function I⋅tb=const until, at a critical duration tc, a constant value is reached where thresholds become independent from signal duration. The critical durations are frequency-dependent following the general function: tc=p⋅fq (with q&lt;0). This frequency-dependent nonlinearity could alos be extracted from available data on human hearing. The present results and respective data of the human ear are discussed with reference to a critical-band-related summation theory assuming fixed critical bands even for very short signal durations.
Subject Classification: [43]65.68, [43]65.75, [43]65.35; [43]80.50.
Temporal masking-level differences: The effect of mask duration
Authors: Lakey J. Radford 
Published: October 2005

Psychometric functions were obatained for the interaural conditions NoSo and NoSπ in both forward and backward masking using masks of different durations. In addition, data were collected for the Sm, Sπ and So conditions without an external mask. The slope parameter k and the signal level required for 76% correct detection were computed with a least-squares technique. The results were that both temporal masking and temporal masking-level differences (MLDs) increased monotonically with longer mask durations. This mask-duration effect was more pronounced for forward masking than for backward masking. Without an external mask, the signal was about 3 dB more detectable in the So configuration than in the Sπ configuration, and it was about 4 dB more detectabe in the Sπ configuration than in the Sm configuration. The psychometric functions were generally steeper for the NoSπ condition than for the NoSo condition in forward masking, but not in backward masking. They were also steeper for the Sπ condition than for either the Sm or So conditions without an external mask. The temporal properties of a typical detection model consisting of a filter centered at the stimulus frequency followed by a rectifier and a final ’’leaky’’ integrator were found to explain much of existent temporal masking data. Signal:500Hz, 8 msec; interstimulus interval: 5–10 msec; mask: wide-band noise; method: two-interval forced choice.
Subject Classification: [43]65.62, [43]65.58, [43]65.68.
Acoustic fluctuations in the open ocean—A measurement using a fixed refracted path
Authors: Ewart Terry E. 
Published: October 2005

Amplitude and phase (transit time) fluctuations in pulses sent between a fixed transmitter and a fixed receiver over a wholly refracted 17.2-km path were recorded for 144.5 h. The sites were the southwest flank of Cobb Seamount and a lesser peak 17.2 km away, both at 1000 m depth. Eight-cycle pulses at 4166 Hz and 16-cycle pulses at 8333 Hz were sent alternately every 15.7 sec and received at three receivers located at 0, 5, and 15 m along a horizontal arm located perpendicular to the transmission path. Power spectra have been computed from the time series of phase and amplitude at a single receiver and the phase difference between two receivers. Extreme care was used in the analysis of the data to ensure that the time series obtained represented a single path. The power spectra of the phase data exhibit dominant tidal peaks at 24, 12.4, and 6.2 h; the power spectra of the amplitudes show less evidence of the tides. Between the inertial frequency and the Väisälä frequency, the power spectra of the phase, amplitude and phase difference fall off at approximately ω−3, ω−1, and ω−1/2, respectively. The power spectra of the phase differences for the 15-, 10-, and 5-m spacings scale according to a plane wave arrival. The phase-difference variance is below theoretical predictions, and the amplitude variance is above theoretical predictions. The high-amplitude variance is tentatively identified as ’’micro’’ multipath interference. Evidence is presented to show that the oceanographic regime of the Cobb Seamount area is typical of the open ocean environment.
Subject Classification: [43]30.20, [43]30.25.
Temporal masking of a click by noise in diotic and dichotic listening conditions
Authors: Berg Kathleen , Yost William A. 
Published: October 2005

Forward, backward, and combined forward–backward masking of a 1-msec click by noise bursts were examined for diotic and dichotic stimulus configurations. The silent interval between the noise masker and the click ranged from 0 to 40 msec for forward and backward masking conditions. For combined forward–backward masking the silent interval between the two noise maskers ranged from 1 to 60 msec, and the click was positioned at 10-msec intervals within this gap. Masking level differences (MLD’s) were obtained for all temporal conditions studied, but were largest for backward masking when the interval between the masker and click was 0 msec. For the combined forward–backward masking procedure, the effects of forward and backward maskers were roughly equivalent in the homophasic condition, but for the antiphasic condition the backward masker was considerably less effective than the forward masker. For homophasic stimuli, the magnitude of additional masking was dependent upon masker intensity. There was little or no evidence of additional masking for antiphasic stimuli.
Subject Classification: [43]65.58, [43]65.62, [43]65.68.
Consonant environment specifies vowel identity
Authors: Strange Winifred , Verbrugge Robert R. , Shankweiler Donald P. , Edman Thomas R. 
Published: October 2005

Past studies have shown that, while vowels can be produced with static vocal tract configurations, the resulting steady-state tokens are misidentified frequently by naive listeners. The first experiment compared the perception of isolated vowels with vowels spoken in a fixed consonantal frame by the same set of 15 talkers. Vowels in /p–p/ syllables were identified with far greater accuracy than were comparable isolated vowels in both single and multiple-talker conditions. Acoustical analyses of the test tokens showed that the poor intelligibility of isolated vowels could not be attributed to talkers’ failure to produce these vowels correctly. In a second experiment, vowels in syllables in which the initial and final stop consonant varied unpredictably from item to item were still identified with greater accuracy than were isolated vowels. These results offer strong evidence that dynamic acoustic information distributed over the temporal course of the syllable is utilized regularly by the listener to identify vowels.
Subject Classifications: [43]70.30, [43]70.40, [43]70.70.
Toward a more general integral formulation of the pressure field of an echosonde aperture antenna
Authors: Adekola S. A. 
Published: October 2005

The basis for improvements in acoustic echo-sounding (echosonde) antenna characteristics is analyzed. The results are based on a more general radiation integral formulated from the time-independent wave equation for an acoustic wave, using a cylindrical antenna as a model. Employing common forms of aperture field distributions across the upper transmitting aperture of the antenna, a Fresnel-region field quantity, which is expressed in a closed form using Lommel’s series, is obtained. An echosonde antenna design meeting the requirements of previous specifications is made from the numerical results of the farfield patterns in order to show the validity of the results. The design permits the operation of the antenna in urban environments since irritating noise levels are kept low. The height of the antenna shielding cuffs reduces the 90° side-lobe level (ground level) by 3.85 dB at the height of 1 ft through 40 dB at 13 ft. A 90° side-lobe reduction of 38.6 dB, which agrees with predictions, is obtained for the more appropriate height of 12 ft; diameters of 4 and 12 ft for the lower illuminating—and upper transmitting—apertures, respectively. The results, reported for acoustic carrier frequencies of 2 and 5 kHz, indicate that small values of the antenna height are untenable in echo-sounding operation.
Subject Classification: [43]85.40; [43]20.15, [43]20.30, [43]20.55.
Harmonic vibrations of isotropic, elastic, and elastic/viscoelastic three-layered plates
Authors: Durocher L. L. , Solecki R. 
Published: October 2005

A fourth-order equation has been derived that is suitable for analyzing symmetrically constructed, isotropic three-layer plates. The formulation includes the effects of shear deformation in each layer, as well as the rotatory inertia of the composite while enforcing continuity of displacements and shear stresses at layer interfaces. From virtual work considerations, the natural boundary conditions are also derived in an invariant form. Since the equations of motion and boundary conditions are tensor equations, an arbitrarily shaped plate can be analyzed using the most convenient coordinate system. Natural frequency comparisons have shown that the current theory is in excellent agreement with an exact elasticity solution, at least in the range where such data exists. By using the complex modulus concept or the correspondence principle, the governing equation can be used in analyzing composite plates that consist of (a) a viscoelastic core sandwiched between similar elastic faces and (b) an elastic plate with two symmetric viscoelastic coatings. Several examples have been analyzed to illustrate the damping that can be obtained by the use of a viscoelastic inner layer.
Subject Classification: [43]40.20, [43]40.24.
Deep-ocean dynamics for environmental acoustics models
Authors: Watson J. G. , Siegmann W. L. , Jacobson M. J. 
Published: October 2005

A hydrodynamic model for flows in the deep ocean is developed in order to determine the velocity field and sound-speed distribution for use in acoustic transmission problems. A scaling of the governing equations is constructed that explicitly includes sound speed. A subsequent perturbation expansion yields a set of approximate equations for motions nearly in geostrophic and hydrostatic balance, such as large-scale, quasisteady currents and Rossby waves. The quasigeostrophic potential vorticity equation or a simpler limiting case of this equation arises from the perturbation scheme to govern higher-order dynamics of the stream function for these flows. The results of the analysis are used to obtain a significant simplification of the ray equations of geometrical acoustics for moving media. For the particular class of flows considered here, the model equations are applicable if the ocean depth is about 1 km or greater and if the spatial and temporal scales of variation of the motions are of the order of 100 km and 10 days, respectively. A solution for a flow such as the Antilles current is derived. Isospeed curves for this solution are shown in a plane perpendicular to the current, and specific features of the curves are discussed and interpreted.
Subject Classification: [43]30.25, [43]30.20; [43]28.60.
Experiments with two types of electromagnetic ultrasonic transducers
Authors: Kawashima Katsuhiro 
Published: October 2005

Two types of electromagnetic ultrasonic transducers were made and tested on mild steel, stainless steel, and aluminum. One of the transducers generates and detects a relatively large amount of longitudinal wave and simultaneously a small amount of radially polarized transverse wave in nonmagnetic metal. The other is for a large amount of radially polarized transverse wave and a small amount of longitudinal wave, also in nonmagnetic metal. Both transducers showed different characteristics for ferromagnetic metal, giving greater efficiency to the radially polarized transverse wave. It was also shown experimentally with an electromagnetic transducer that the mode conversion between longitudinal waves and radially polarized transverse waves occurs fairly efficiently at a vertical reflection.
Subject Classification: [43]35.60, [43]35.80; [43]85.40, [43]85.48.
Experiments involving sonification of liquid helium at 4.2 K in the cathode–anode interspace of a photodiode tube
Authors: Smith C. W. , Burke G. F. , Rooney J. A. 
Published: October 2005

An experimental study of the photo-injection of electrons into liquid helium at 4.2 K during sonification shows a dramatic increase in the observed photocurrent. The increase in photocurrent results from a sonically induced increase of the electron bubble mobility and a reduction in mean thermalization time due to an increase in local density fluctuations in the vicinity of the photocathode. The increase in mobility of the electron bubbles in the sound field has the same functional dependence as static pressurization, suggesting an effective rectification mechanism. Studies in which the sound field is abruptly turned off show that the half-life of potential cavitation nuclei within the microbubble field is 7.6 sec. These sonically induced changes in the electron microbubble photocurrent provide a unique method for the study of the formation and population dynamics of cavitation nuclei.
Subject Classification: [43]35.47, [43]35.32.
Susceptibility to auditory fatigue: Comparison of changes in cochlear nerve potentials in the guinea pig and chinchilla
Authors: Mitchell Curt 
Published: October 2005

The susceptibilities of the guinea pig and chinchilla to acoustic fatigue are compared. For this comparison they were exposed to a 6-kHz tone. The exposures were within the range of 60–110 dB SPL. The N1 potential of the cochlear nerve and the cochlear potential were recorded before and after exposure. Both species suffered greatest N1 changes a 1/2 octave above the exposure tone. No appreciable changes in cochlear potential were observed. In agreement with previous studies for equal SPL’s, the chinchilla was found to be more susceptible to fatigue than the guinea pig. However, when the exposures are based on maximum cochlear-potential output, these animals suffer similar losses in N1. This suggests that impedance differences in their ears accounts for the susceptibility difference. Nerve fatigue is described and found related to hair cell distortion.
Subject Classification: [43]65.66, [43]65.40, [43]65.42.
Spatial coherence in multipath or multimodal channels
Authors: Smith P. W. 
Published: October 2005

An integral expression for the spatial coherence function of pure-tone sound fields is formulated under hypotheses that the component fields of individual paths or modes are locally plane waves and mutually incoherent in the average. The total field is not assumed to be a Gaussian random variable. The resulting coherence is quasi or locally homogeneous, varying slowly with average position as the strength of the component fields change. Statistical estimates for the contributions of these components are taken from existing literature on average transmission loss. The expression for coherence has an explicit dependence on the environmental parameters, the range, and the depths of source and receivers. Numerical results and approximate expressions are developed for channels characteristic of shallow and deep water.
Subject Classification: [43]20.15; [43]60.20.
Attenuation of shear waves in marine sediments
Authors: Hamilton Edwin L. 
Published: October 2005

The objectives of this report are to review selected published measurements of the attenuation, or energy damping, of low-strain shear waves in surficial water-saturated sands and silt clays (mud) which might occur as marine sediments. In various computations, a linear viscoelastic model is favored in which velocity dispersion is negligible, the linear attenuation is proportional to the first power of frequency, and the specific dissipation function, 1/Q, and the logarithmic decrement are independent of frequency. The logarithmic decrement is favored as a measure of energy damping because of research in soil mechanics. The very sparse data indicate that in water-saturated sands and silt clays, the logarithmic decrements are mostly between 0.1 and 0.6. If approximate values of shear wave energy losses are required for generalized computations, it is suggested that a value for the logarithmic decrement of 0.30±0.15 be assumed for sands, and 0.2±0.1 for silt clays. Measured logarithmic decrements of compressional waves in sands average about 0.10±0.03; in silt clays about 0.02±0.01. The average values of the ratio of compressional-to-shear-wave logarithmic decrements, using the above average values, would be 0.3 for sands and 0.1 for silt clays.
Subject Classification: [43]30.20; [43]40.50, [43]30.30.
High-frequency model for sound transmission from an airborne source into the ocean
Authors: Meecham William C. 
Published: October 2005

The problem of the transmission of sound from an airborne source into the ocean, through the rough ocean surface, is considered. A high-frequency approximation is adopted, requiring for its validity that the sound wavelength in air be (much) less than typical radii of curvature and than typical displacements of the ocean surface. This condition is approximately met in many applications. Attention is focused on observation directions with small grazing angles. The result is approximately unaffected by surface roughness when the grazing angle is greater than the rms surface slope, and approaches a limit (proportional to the variance of the surface slope) when the grazing angle is less than the slope. The result is independent of the source height, under the stated approximations, as is also the case for the transmission through a plane surface. The enhancement due to surface roughness, even at moderate wind speed, ranges up to 10 dB.
Subject Classification: [43]30.25.
Comments on ’’Sabine’s reverberation time and ergodic auditoriums’’ [J. Acoust. Soc. Amer. 58, 643–655 (1975)]
Authors: Gomperts M. C. 
Published: October 2005

Joyce’s paper is, in fact, a confirmation of the author’s standpoint that, generally, Sabine’s formula does not hold. A reverberation formula from recent literature, referred to by Joyce, is shown to be false. Instead, a more correct formula is given here.
Subject Classification: [43]55.20, [43]55.30, [43]55.55.
Vibrations of an infinite plate with a frequency independent Q
Authors: Caputo Michele 
Published: October 2005

The dissipation in an elastic medium is represented by a dissipation mechanism which is similar to one used in an earlier paper [M. Caputo, Geophys. J. R. Astron. Soc. 13, 529–539 (1967)], but is simpler and has a frequency-independent Q−1. The vibrations of a plate are studied by obtaining the eigenfrequencies, the amplitude of the displacement, the dispersion relation, the Q−1, the hysteresis cycle, and the yield stress.
Subject Classification: [43]40.24.
Comfortable effort level: An experimental variable
Authors: Brown W. S. , Murry Thomas , Hughes David 
Published: October 2005

It is not uncommon to read in speech studies that subjects were instructed to produce speech samples at a ’’comfortable effort level.’’ In many cases the experiments have made the assumption that this level of effort is more or less constant over repeated occurrences. The purpose of this study was to test the constancy of comfortable effort level in speakers’ utterances across experimental sessions. Sixteen speakers were recorded on each of five successive days while producing a series of vowels and phrases. The only instruction to the speakers was to repeat the utterances at a comfortable effort level. Measures of speaking fundamental frequency (SFF) and vocal intensity (SPL) were obtained from the recordings. Results indicate that variability in both SFF and SPL occurred in the utterances; in many cases (especially for SPL) this variability was considerable. These results suggest that experiments desiring constant vocal productions must be more specific in providing instructions to subjects since comfortable effort level can not be assumed to be constant from one experimental session to the next (especially from day to day).
Subject Classification: [43]70.40, [43]70.20.