bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of number of repetitions and intensity level of stimuli varying in VOT on verbal transformations
Authors: Ohde Ralph N. , Sharf Donald J.
Published: October 2005

The purpose of this study was to investigate the perception of transformations by varying the voice onset time (VOT) of the repeating stimulus, its repetition number, and intensity level. Fifteen subjects rated the 5-, 25-, and 55-ms VOT stimuli during periods of repetitions so that transformations could be identified according to their place and voicing characteristics. The number of stimulus repetitions was 5, 32, or 95, and the sound-pressure level of the repeating stimulus was 50, 70, or 90 dB. The major findings were as follows: (1) The 90-dB level condition produced significantly more transformations than either the 50- or 70-dB conditions for the 55-ms stimulus only; (2) A significant difference in number of transformations was obtained for each paired comparison of the 55-ms stimulus, but only between the 5-and the 32- and 95- repetitions pairs for the 5 and 25 ms stimuli; and (3) Significant correlations were obtained between the voiceless and alveolar features of transformations for the 55-ms stimulus, and between the voiced and alveolar and velar features of transformations for the 5- and 25-ms stimuli. The findings support a transformation process sensitive to voicing and place cues and a peripheral component of transformations.
Long-wavelength propagation in composite elastic media II. Ellipsoidal inclusions
Authors: Berryman James G.
Published: October 2005

A self-consistent method of estimating effective macroscopic elastic constants for inhomogeneous materials with ellipsoidal inclusions is formulated using elastic-wave scattering theory. The method is a generalization of the method for spherical inclusions presented in the first part of this series. The results are compared to the Kuster–Toksöz estimates for the elastic moduli and to the rigorous Hashin–Shtrikman bounds and Miller bounds. For general ellipsoidal inclusions, our self-consistent estimates satisfy both the Hashin–Shtrikman bounds and the more stringent Miller bounds, whereas the Kuster–Toksöz estimates for nonspherical inclusions do not satisfy even the Hashin–Shtrikman bounds in general. Our self-consistency conditions for the cases of needle and disk inclusions differ from those of Wu, Walpole, and Boucher. Since our results are in better agreement with the rigorous bounds, it is concluded that our results are to be preferred. The method is also briefly compared to other self-consistent scattering theory approaches. The theory is used to calculate velocity and attenuation of elastic waves in fluid-saturated media with oblate and prolate spheroidal inclusions.
Scattering of an obliquely incident acoustic wave by an infinite cylinder
Authors: Flax Lawrence , Varadan V. K. , Varadan V. V.
Published: October 2005

Expressions are derived for the scattered farfield pressure which results from the illumination of an infinite aluminum cylinder by a plane acoustic wave, whose propagation direction makes an arbitrary angle, α, with the normal to the cylinder axis. Computations are made at angles between α=0 ° and the Rayleigh critical angle, α=31.3 °. Changes in the scattered field are related to shifts in the paths of geometric and elastic surface waves from circumferential at α=0 °, to helical, to axial Rayleigh surface waves generated at the Rayleigh critical angle.
Weighty voices and shaky evidence: A critique
Authors: Cohen J. R. , Crystal T. H. , House A. S. , Neuburg E. P.
Published: October 2005

In a series of recent papers, claims have been made that the human voice carries information that is available to a listener for the identification of certain physical characteristics of the talker. In this note these claims are challenged, both by a reanalysis of some previous data using more-standard statistical tests, and by an experiment in which equally significant results were obtained by guessing ’’talker’’ weights without listening to speech samples.
A note on possible culture-bound effects in frequency discrimination
Authors: Burns Edward M. , Sampat K. S.
Published: October 2005

Tanner and Rivette [J. Acoust. Soc. Am. 36, 1465–1467 (1964)] reported that three native speakers of Punjabi were unable to discriminate frequency differences an order of magnitude greater than the usual DL’s for frequency. This paper is often cited as evidence for culture-bound effects in frequency discrimination. We obtained frequency DL estimates from 34 observers comprising a number of linguistic groups, including Punjabi. No evidence of a disability in frequency discrimination was found in any of the groups.
Comment on ’’Is pitch a learned attribute of sounds? Two points in support of Terhardt’s pitch theory’’ [J. Acoust. Soc. Am. 66, 1210 (1979)]
Authors: Houtsma A.
Published: October 2005

The two points raised in Divenyi’s letter yield a highly unlikely result when jointly considered: That the people of Java may have difficulties understanding speech.
Analysis of the click-evoked brainstem potentials in humans using high-pass noise masking. II. Effect of click intensity
Authors: Eggermont J. J. , Don M.
Published: October 2005

Derived narrow-band brainstem responses were obtained for click levels of 10–60 dB SL in normal hearing subjects. The amplitudes and latencies of the wave I, wave III, and wave V components in the derived BSER were studied as a function of click intensity. Characteristic differences were found between the input–output behavior of waves I and III on one hand and wave V on the other hand, especially for the low-frequency narrow bands (center frequencies of 0.5 and 1.0 kHz). While the wave I and wave III (peak-to-succeeding trough) amplitude showed a small (20–30 dB) dynamic range with saturation effects, the wave V amplitude continued to increase across the intensity range studied. At the high-frequency end (narrow-band center frequencies of 4 and 8 kHz), wave V also showed saturation. It is suggested that this difference across center frequency (place of origin along the cochlear partition) is responsible for the dominance of wave V at low-frequency stimulation (e.g., with tonebursts). The latencies of the three waves studied maintained their constant interwave delays across the observed intensity range in each narrow band. Quite large (up to 3.5 ms) increases in the narrow-band latencies were found for decreasing click levels; this is comparable in value with those for the unmasked BSER although the mechanism seems to be different. The major contribution to the BSER which determines its latencies, originates at 60 dB SL from the 8-kHz region but at low SL (10 and 20 dB) from the 2-kHz region. At these low intensity levels, the contribution from the apical part of the cochlea, however, is still of the same size as that from the high-frequency end.
The effect of array errors on frequency-domain adaptive interference rejection
Authors: Keating P. N.
Published: October 2005

An existing adaptive beamforming technique, known as frequency-domain adaptive interference rejection (FAIR), is examined for robustness with respect to nonsystematic array errors. It is concluded that, for array position errors below ±10% of the mean spacing, the FAIR technique continues to be effective. However, for special situations where large errors are encountered or where the noise situation is so favorable that better interference rejection is worthwhile, error compensation might become necessary, and a self-calibration scheme is briefly described.
Ultrasonic imaging system using orthogonal function wavefronts
Authors: Sato Takuso , Ikeda Osamu , Azuma Tomoji
Published: October 2005

A new ultrasonic imaging system that employs the orthogonal function wavefronts derived from the a priori knowledge of the second-order moment function about a class of objects is presented. First, it is shown theoretically that this new method has the ability to reconstruct images of sample objects of a given class with a higher signal-to-noise ratio (SNR) in a shorter time than the conventional beamforming methods. The assumptions are confirmed by numerical analyses and experiments carried out by using a prototype of an orthogonal function applied array imaging system.
Axisymmetric free vibration of thick annular plates
Authors: Sundara K. T. , Iyengar Raja , Raman P. V.
Published: October 2005

Free vibration of annular plates has been studied using the method of initial functions. Numerical results of the natural frequencies are obtained for two typical support conditions. The present results depart from the classical plate theory for higher modes as well as for thicker plates, but is in good agreement with Mindlin’s improved plate theory.
Hearing in Glires: Domestic rabbit, cotton rat, feral house mouse, and kangaroo rat
Authors: Heffner Henry , Masterton Bruce
Published: October 2005

Behavioral audiograms were determined for four species of Glires: one lagomorph (domestic rabbit, Oryctolagus cuniculus) and three feral rodents (cotton rat, Sigmodon hispidus; house mouse, Mus musculus; and kangaroo rat, Dipodomys merriami). Considerable variation in hearing ability was found among the four species with low-frequency hearing limits ranging over 5-1/2 octaves from 50 (kangaroo rat) to 2300 Hz (feral mouse) and high-frequency hearing limits ranging from 49 (rabbit) to 90 kHz (feral mouse). Comparison of the characteristics of each audiogram with the audiograms of other animals of the same Order, Cohort, and Class provide further evidence for the validity of two relationships: (1) interaural distance is strongly and inversely correlated with high-frequency hearing ability, and (2) good high-frequency hearing is apparently incompatible with good low-frequency hearing in most, if not all, land mammals. Furthermore, it is shown that cotton rats and feral mice possess the ability to perform frequency discriminations even at very high frequencies, indicating that there is probably no difference about the way in which they perceive high and low-frequency sounds. Finally, it is shown that kangaroo rats are not unusual in their ability to localize brief sounds, indicating that these animals have not compromised this ability in their acquistion of their unusual low-frequency sensitivity.
Relation between psychophysical data and speech perception for hearing-impaired subjects. I
Authors: Dreschler Wouter A. , Plomp Reinier
Published: October 2005

In a heterogeneous group of ten hearing-impaired adolescents, relations are studied between several psychophysical test results and speech reception thresholds in quiet and noise. To examine the results, data-reduction techniques were used to extract the most relevant parameters. High correlations were found between the intelligibility of speech in noise on the one side, and vowel-perception parameters resulting from INDSCAL analysis (frequency resolution parameters, critical bandwidth and critical ratio) and audiogram parameters on the other.
Normal input admittance of a disk in a thin flat plate
Authors: Smith P. W.
Published: October 2005

The input admittance for a rigid, massless, circular disk undergoing uniform normal motion in a thin flat plate is found as a function of disk radius, within the limitations of the classical theory for thin-plate dynamics. A modal reciprocity theorem is derived which relates the real part of the input admittance, for any single mode of deformation of the source region, to the mean-square response velocity in that mode when it is excited by an isotropic, homogeneous, stochastic field of waves incident from the plate.
Scattering of elastic waves from planar cracks in isotropic media
Authors: Visscher William M.
Published: October 2005

Cracks, which constitute an important class of defects in materials are mathematically idealized by planar voids of zero thickness whose surfaces are traction free. A propagating wave will be scattering by such a flaw. Among the properties of the scattering cross section which we establish are: (i) For any wavelength, and the incident direction normal to the plane of the crack, the scattered intensity is symmetric under reflection through the plane of the crack. (ii) For long wavelength incident waves (Rayleigh regime) the cross section is determined by six real parameters for an arbitrarily shaped flat crack. (iii) If the crack is fluid-filled, then it is invisible to longitudinal waves of any wavelength incident either in the crack plane or normal to it. (iv) The cross section of a fluid-filled crack is symmetric under reflection through the crack plane for any incident angle or wavelength.
Nonlinear generation of harmonics in sound radiation from a vibrating planar boundary
Authors: Ginsberg Jerry H.
Published: October 2005

This is an analysis of the finite amplitude acoustic waves that are induced by harmonic vibration of a region in an infinite planar boundary. Only situations leading to two-dimensional waves in inviscid fluids are considered. A perturbation formulation is employed to obtain the first-order (linear) and second-order (first nonlinear correction) terms in the velocity potential. A Fourier transform leads to a description of the linear potential in terms of propagating and evanescent nonuniform planar waves occurring in a continuous spectrum of transverse wavenumbers. The linear solution is used to evaluate the source terms for the second-order potential. The portion of the latter which exhibits cumulative growth of higher harmonics is evaluated by a method based on the principle of stationary phase. The results indicate that harmonic generation at a specific transverse wavenumber is primarily independent of the response associated with other wavenumbers.
Propagation through a three-dimensional eddy including effects on an array
Authors: Baer Ralph N.
Published: October 2005

Propagation through a three-dimensional model of the sound–speed structure of an eddy is studied by means of a three-dimensional computer model based on the parabolic approximation to the reduced wave equation. Illustrations of the effect of the eddy on transmission loss in both vertical and horizontal planes are provided. Refractive variations cause a 20-km difference in the range of a given acoustic feature (such as a convergence zone) between the vertical plane through the eddy center and one exterior to the eddy. Eddy-induced variations on acoustic array performance are also considered. It is shown that an eddy can produce over one-half degree deviation in apparent source bearing angle. The influence on the acoustic 3-dB angular width and array signal gain are noted.
Short-range acoustical effects of vertical and horizontal source-motion variations in a deep ocean
Authors: Kays J. L. , Jacobson M. J. , Siegmann W. L. , Jacyna G. M.
Published: October 2005

Using ray theory the combined effects of time-dependent changes in source depth and receiver-source range are examined for a cw signal transmitted over relatively short ranges. Approximating deep-ocean sound speed with a bilinear profile, general results are obtained when the receiver is taken fixed on the surface, while the source moves on an arbitrary constant–velocity path above the SOFAR axis. Time-dependent expressions for the amplitude and phase of the received multipath signal are used to present numerical data for suitably restricted time intervals. Then, the effects of source path and speed are analyzed using convenient formulas which closely approximate numerical results. For strictly horizontal motion, total-field phase rate remains approximately proportional to time, source frequency, speed, and horizontal receiver-source range, but virtually independent of source depth. However, when source depth varies with time, overall linear phase patterns are interrupted by regularly spaced, brief changes in phase rate. The periodicity of these changes, and accompanying amplitude fades of up to 35 dB, are virtually proportional to vertical speed, source frequency, and range, but invariant with changes in horizontal speed, direction, and initial source depth.
Instantaneous power spectra
Authors: Grace O. D.
Published: October 2005

Conventional spectral analysis methods do not describe the distribution of signal power in both time and frequency simultaneously. Time dependent Fourier transforms are defined to extend the conventional theory to include instantaneous energy and power spectra for the past and future signal. These spectra are combined to define an instantaneous power spectrum (IPS) of the entire signal. The IPS is a noncausal mathematical property of the signal from which observable properties can be derived, e.g., the lagged window Fourier transform estimate of the time-frequency variations of the signal. The IPS for a nonstationary process is shown to be given by the Fourier transform of Loeve’s generalized power spectrum of the process and to be a generalization of the Wiener–Kintchine theorem. It is also shown to represent the special cases of the stationary process, the locally stationary process and the deterministic process.
Wallace C. Sabine, acoustical consultant
Authors: Beranek Leo L. , Kopec John W.
Published: October 2005

Twenty-two correspondence files of Wallace C. Sabine, discovered recently at the Riverbank Laboratory, contain a rich supply of solutions to acoustics and noise control problems. Differing from his published papers [Collected Papers on Acoustics, edited by T. Lyman (Dover, New York, 1964)] and notebooks [J. Acoust. Soc. Am. 61, 629–639 (1977)], they are records of Sabine’s extensive activities between 1909 and 1916 as an acoustical consultant. His projects covered auditorium acoustics, building noise transmission, the reduction of noise from industrial plants and from machines. Of interest also are Sabine’s findings on a constant-power sound source, his part in the invention of acoustic tile, and his policies and ethical standards as an acoustical consultant.
Predicting consonant confusions from acoustic analysis
Authors: Dubno Judy R. , Levitt Harry
Published: October 2005

Acoustic measurements of nonsense syllables in quiet and in noise were used to predict the pattern of consonant confusions made under those conditions. Eleven sets of nonsense syllables were presented to normal-hearing subjects in quiet and at a +5 dB speech-to-noise ratio, at five speech levels. A set of acoustic characteristics of the speech stimuli were chosen for analysis and measured using digital speech processing techniques. Results of the recognition task revealed significant effects of consonant voicing, position and vowel context on syllable recognition. The performance-intensity function for the quiet condition rises more steeply than the function obtained in noise. The effect of noise on consonant recognition is dependent upon the manner in which the consonant is produced, and the location of maximum constriction. Differences in the absolute values of the acoustic parameters of syllable pairs were used to predict their percentage of confusion. A set of acoustic variables was isolated which was found to be the best predictor of confusion percentages. Although the sets of acoustic variables were different for various syllable types and test conditions, three variables (consonant energy, consonant spectral peaks, consonant-to-noise ratio) were used in a majority of the predictions.
Stop identification from vocalic transition plus vowel segments of CV and VC syllables: A follow-up study
Authors: Ohde Ralph N. , Sharf Donald J.
Published: October 2005

In a recent article in the Journal [L. C. W. Pols and M. E. H. Schouten, J. Acoust. Soc. Am. 64, 1333–1337 (1978)], it was concluded that perception experiments which present CV syllables with the consonant bursts deleted invoke a ’’click sensation’’ and that this sensation has a deleterious affect on the perception of the consonants. In order to directly assess the ’’click sensation’’ hypothesis, a computer-based speech editing system was used which smooths onsets and offsets of stimuli and therefore eliminates the possibility of an acoustic click. Subjects identified voiced and voiceless stops from vocalic transition+vowel stimuli edited from CV and VC syllables. The findings were as follows: (1) Consonant identification from vocalic transition+vowel segments in VC syllables was significantly greater than that from vocalic transition+vowel segments in CV syllables; and (2) The superiority of the scores for VC vocalic transition+vowel segments was found for both voiced and voiceless stops, but it was not as great for voiced stops. Although there are differences in magnitude of findings between this study and those which employed other deletion techniques, the reliability and direction of the results were similar. The results do not support the ’’click sensation’’ hypothesis and suggest that other mechanisms must account for differences between CV and VC syllables in the perception of sound segments.
Implications of a critical level in the ear for assessment of noise hazard at high intensities
Authors: Price G. Richard
Published: October 2005

The argument is advanced that there is a critical level (CL) for the ear at high intensities where the loss mechanism undergoes a fundamental change. In physiological terms, CL probably represents the intensity at which a given level of mechanical stress is reached in the Organ of Corti. Electrophysiological, histological, and threshold shift data support this contention. Further, CL varies as a function of the spectrum of the sound. A preliminary estimate of the freefield SPL reaching CL in the human ear has been calculated as has been the distribution of CL. The implications for human exposure and damage-risk criteria are discussed.
Quantitative acoustical assessment of wound maturation with acoustic microscopy
Authors: O’Brien W. D. , Olerud J. , Shung K. K. , Reid J. M.
Published: October 2005

Preliminary results of the ultrasonic characterization of cutaneous wound tissue and surrounding margin, obtained with the scanning laser acoustic microscope, show an increase in the speed of sound and in the acoustic heterogeneity as a function of wound age. As the wound age increased, the following results were noted: (1) The wound area, initially quite homogeneous in acoustic appearance, became more heterogeneous; (2) the acoustic appearance of the wound tended to become similar to that of the adjacent tissue; and (3) the ultrasonic velocity of the wound area increased from a range of 1540–1575 m/s at 7 days to a range of 1700–2000 m/s at 35 days.
Underwater sound from surface waves according to the Lighthill-Ribner theory
Authors: Lloyd Stuart P.
Published: October 2005

The acoustic source density given by Ribner’s version of the Lighthill theory is calculated for a stochastic surface gravity wavefield. A Green function gives the acoustic farfield, as a volume integral. The method eliminates some of the complications involving the moving ocean surface. For a homogeneous ocean, the farfield acoustic spectrum agrees with the spectrum of Hughes [J. Acoust. Soc. Am. 60, 1032–1039 (1976)], and at low frequencies with the spectrum of Brekhovskikh [Izv. Atmos. Ocean Phys. 2, 582–587 (1966)], after certain corrections are applied to their results. At high frequencies, the Brekhovskikh spectrum is larger by a factor (5/4)2.
Resonance theory of bubbly liquids
Authors: Gaunaurd G. C. , Überall H.
Published: October 2005

Host materials containing a large number of small inhomogeneities (such as gas bubbles suspended in a liquid) may be characterized by a set of ’’effective’’ material parameters which differ from those of the host material, as well as from those of the inhomogeneity. A method proposed by Ament [U.S. Naval Research Lab. Tech. Rept. 5307 (1959)] is used here to obtain the effective densities and the (complex) effective propagation constant of sound for liquids containing spherical gas bubbles, by comparing low-frequency sound scattering from the bubbles with scattering from a sphere of bubbly liquid. In contrast to previous treatments, some higher-order terms in the low-frequency expansion are retained here in order to include effects of the monopole resonance. Numerical results are obtained for air bubbles in water and the effects of surface tension, shear viscosity of the liquid, and thermal conduction in the gas, as derived by Nishi [Acustica 33, 65–74 (1975)], are included in our theory and displayed in the graphs.
Effects of multiple scattering and acoustic interactions among two parallel hydrophones and a planar baffle
Authors: Gustafson Harry L. , Stepanishen Peter R.
Published: October 2005

When acoustic energy is incident on a collection of objects, multiple scattering and interaction occur. As a specific case of interest, the acoustic scattering of a plane wave by a system of two cylindrical hydrophones and a planar baffle is investigated. To form a mathematically tractable problem, the cylinders are considered to be infinite in length, and the baffle is considered to be infinite in extent. Three different approaches are presented to predict the scattered fields and hydrophone outputs which result from a harmonic plane-wave excitation. The approaches correspond to varying levels of analytical complexity which include multi-order scattering, zero-order scattering, and no scattering or interactions, respectively. Theoretical results based on the approaches are presented and discussed. The results of a limited experimental program are used to substantiate the validity of the analytical results.
Scattering theory approach to the identification of the Helmholtz equation: A nearfield solution
Authors: Weglein Arthur B. , Silvia Manuel T.
Published: October 2005

Expressing the Helmholtz equation as a Schrödinger-type equation with a frequency-dependent potential allows one to use the techniques of inverse scattering to determine the potential from farfield scattering information. These techniques were designed to accomodate farfield experimental data which was generated by a plane-wave probe. Here, we consider the problem of finding the potential when (1) the scattering information is restricted to the nearfield and (2) the incident probes are assumed to be arbitrary, unknown, and not necessarily reproducible from experiment to experiment. The basic idea is to derive the on-shell T-matrix elements (or scattering amplitudes), which are required by the farfield inverse scattering techniques, from nearfield scattering information. Once the T matrix is known, the potential follows from the techniques of inverse scattering. [See V. A. Marchenko, Math. Rev. 17, 740 (1956) or M. Razavy, J. Acoust. Soc. Am. 58, 956–963 (1975) for the one-dimensional case, and A. B. Weglein, W. E. Boyse, and J. E. Anderson, to be published in Geophysics (1981) or R. G. Newton, Phys. Rev. Lett. 43, 541 (1979) for the three-dimensional case.] Recently, M. T. Silvia and A. B. Weglein [J. Acoust. Soc. Am. 69, 478–482 (1981)], presented a nearfield inverse scattering solution to the acoustic wave equation for the case when the probes were arbitrary, unknown, and not necessarily reproducible. There, the scattering measurements had to include both the field and its normal derivative. In this paper, a more direct approach to the nearfield inverse scattering problem is presented. Furthermore, for this new technique, we demonstrate that when the incident probe is known, only the field on a closed surface is required for a nearfield solution.
Influence of preceding fricative on stop consonant perception
Authors: Mann Virginia A. , Repp Bruno H.
Published: October 2005

The effect of a preceding fricative on the perceived place of stop consonant articulation was investigated in a series of experiments. In experiment 1, we preceded synthetic syllables from two [tV]–[kV] continua with fricative noises appropriate to [ℱ] or [s] and showed that more velar stops are perceived in the context of [s]. Experiment 1 also demonstrated a decrease in the magnitude of this perceptual context effect with increased temporal separation of fricative noise and CV portion, and with introduction of a vowel before the noise, which permitted a subjective syllable boundary after the fricative. Experiment 2 showed that although the effect of the fricative on stop perception declines initially with temporal separation, it may persist in reduced form over intervals as long as 375 ms. Experiment 3 replicated the basic fricative context effect using improved stimuli, but failed to replicate the reduction with an intervening syllable boundary obtained in experiment 1, which presumably was due to the vowel preceding the fricative. Experiments 4 and 5 revealed that the fricative context effect depends both on the phonetic category assigned to the fricative and on the specific spectral properties of the fricative noise. Experiment 5 also revealed a reciprocal effect of the stop consonant on fricative identification. We hypothesize that these perceptual effects serve to compensate for coarticulatory dependencies between stop consonants and preceding fricatives.
Bubble formation in supersaturated gelatin: A further investigation of gas cavitation nuclei
Authors: Yount David E. , Yeung Chick M.
Published: October 2005

Recently, a new cavitation model has been proposed in which bubble formation in aqueous media is initiated by spherical gas nuclei stabilized by surface-active membranes of varying gas permeability. The data which originally motivated this development were obtained mainly by subjecting shallow gelatin samples to rectangular pressure schedules consisting of a rapid compression, equilibration of the sample at some constant increased pressure, and a rapid decompression. Since the initial pressure was ordinarily less than or equal to the final pressure, the magnitude of the initial compression was ordinarily greater than or equal to the magnitude of the final decompression. An equivalent statement for this type of schedule is that the initial overpressure was generally greater than or equal to the final supersaturation. The purpose of the experiment reported here is to test the surfactant cavitation model in the unexplored domain for which the reverse is true, i.e., for which the maximum overpressure is less than the final supersaturation. This domain can be reached by using slow compressions or stepped compressions which permit a significant rise in the dissolved gas tension while the ambient pressure is still increasing.
Acoustic fluctuations due to the temperature fine structure of the ocean
Authors: Unni Santha , Kaufman Charles
Published: October 2005

The effect of oceanic temperature fine structure on sound transmission is investigated. The model used assumes that the layered fine structure is advected horizontally and vertically by the internal waves. Taylor’s frozen turbulence hypothesis is then used to determine the space–time variations in sound speed. We compare our results to those of Ewart’s Cobb Seamount experiment [J. Acoust. Soc. Am. 60, 46 (1976)]. The agreement between the calculated spectrum of the log-intensity fluctuations and the experiment is excellent except at low frequencies (ω≲0.3 cph) and extends, at high frequencies, even beyond the internal wave frequency range. Previous calculations based on the internal wave model of turbulence have consistently underestimated these fluctuations in this frequency range. The agreement between the observed and the previously calculated phase fluctuations is not affected; that is, the fine structure adds little to the phase fluctuations.
Identification and discrimination of a synthesized voicing contrast by normal and sensorineural hearing-impaired children
Authors: Parady Susan , Dorman M. F. , Whaley Patricia , Raphael Lawrence J.
Published: October 2005

The identification and discrimination of a stop-consonant voicing contrast (/da/–/ta/) was assessed in children and adolescents who had moderate, severe, and profound sensorineural hearing losses. The location of the perceptual boundary between /da/ and /ta/ did not differ between normal listeners and listeners with moderate losses. Of the ten listeners with severe losses, five evidenced normal boundaries, three evidenced longer-than-normal boundaries, and two could not identify the stimuli at all. Of the three listeners with profound hearing losses, one could identify normally, and two could not identify at all. For the most part, discrimination data mirrored identification data. However, in some instances listeners were able to discriminate between stimuli they could not differentially identify. These subjects appeared to have the auditory capacity to resolve differences in voice-onset-time but could not use this capacity to make phonetic identification.
Scattering of transient acoustic waves by an inhomogeneous obstacle
Authors: Herman Gérard C.
Published: October 2005

A method is described to compute the scattering of transient, scalar, acoustic waves by arbitrarily shaped, three-dimensional, inhomogeneous, penetrable objects of bounded extent. The problem is formulated in terms of a volume-integral equation over the interior of the scatterer. This integral equation is solved numerically by the marching-on-in-time method. Comparison is made with analytical results for a spherical, homogeneous scatterer, while some numerical results for scatterers of different shapes are presented.
Experiments on single mode excitation in shallow water propagation
Authors: Gazanhes C. , Garnier J. L.
Published: October 2005

The normal mode theory for shallow water propagation is used to develop a method permitting the excitation of a single mode by means of a vertical array of sources. The experiments were carried out in a laboratory tank, in a thin layer of water lying on a thick sand bed. Single mode excitation was performed by a vertical array of 15 piezoelectric transducers, whose gain and polarity depend on the mode to be excited. Single mode propagation between a source array and a receiving array is also examined. The receiving array can simultaneously resolve five modes. In these conditions crosstalk between mode and mode conversion can be studied.
Multipath variability due to the Gulf Stream
Authors: Spindel R. C. , Spiesberger John L.
Published: October 2005

A phase-coded signal with 64-ms resolution was transmitted at 10-min intervals for a 19-day period over two ∠300-km ranges. The acoustic source was moored at 2000-m depth northwest of Bermuda. One receiver was moored at 2000-m depth to the northeast of the source and the other receiver was bottom mounted at ∠1000-m depth near Bermuda. The large (∠0.6 s) travel time change at the Bermuda receiver is probably due in large part to motion of the source mooring in the presence of currents. The multipath arrival pattern at the moored receiver undergoes significant modification due to the presence of a southern meander of the Gulf Stream which intersects this transmission path.
Moving load on a two-layered cylindrical shell with imperfect bonding
Authors: Chonan S.
Published: October 2005

This paper studies the response to a moving ring load of an infinitely long two-layered cylindrical shell with a flexible bond at the interface. Both the dissimilar shells are assumed to bend according to a thick-shell theory. Solutions are obtained by the Fourier transform method with respect to an axial space variable. Numerical results are given for a laminated shell composed of inner hard rubber and outer duralumin shells. The load speed which generates a resonance in the system is calculated. Further, the displacement and the moment in each shell are evaluated for a range of parameters. The results are also compared with those from the classical thin-shell theory.
A frequency-position map for the chinchilla cochlea
Authors: Eldredge Donald H. , Miller James D. , Bohne Barbara A.
Published: October 2005

Frequencies of tones are mapped on to distances along the organ of Corti by associating behaviorally measured threshold shifts with regions of hair-cell loss. The central tendency found for 95 frequency-position matches by four observers on 21 ears is approximated by a straight-line, log-linear relation between frequency and position. Only a small portion of the considerable variation of individual matches around this function could be explained by length of the organ of Corti. Other unidentified factors appear to be responsible for most of these variations.
Invariant characteristics of partial masking: Implications for mathematical models
Authors: Pavel M. , Iverson G. J.
Published: October 2005

The loudness of a tone in a noisy background increases very rapidly above its threshold with increasing intensity of the tone. The particular curve describing loudness growth as measured by a loudness matching paradigm depends on the level of the background noise. We introduce the hypothesis that an increment in masking noise induces a shift of the loudness matching curve in a diagonal direction (the matching curve being plotted in conventional log–log coordinates). This shift invariance is shown here to hold empirically for individual subjects within a monaural loudness matching task, based on a 2IFC paradigm using 1000-Hz tones and a wide band Gaussian noise. Shift invariance places considerable restrictions on models feasible for such data. In conjunction with a very general class of models involving the notion of gain control, the shift invariance property determines all parametric forms possible for the loudness matching functions. The fit of such parametric expressions to the data reported here yields very satisfying results. The resulting model is also found to be consistent with relevant results in the literature.
Calibration technique for acoustic scattering measurements
Authors: Dragonette Louis R. , Numrich S. K. , Frank Laurence J.
Published: October 2005

Tungsten carbide spheres are used as calibration targets in laboratory acoustic scattering measurements. Though the steady-state response of any metal sphere in water greatly differs from a rigid body return, over almost the entire frequency spectrum, the rigid body and elastic returns can be separated in a short pulse, broadband experiment. This rigid body echo can then be used as a reference to normalize the scattering returns from targets of interest.
Discrimination of the ’’tempo of frequency change’’ cue
Authors: Godfrey John J. , Millay Kathleen K.
Published: October 2005

The results of identification and two oddity discrimination tests with a stop versus glide continuum are presented. When the oddity method is combined with ’’facilitation,’’ i.e., by repeating one of the stimulus tokens ten times before each oddity triad, discrimination is considerably improved. The shape of the resulting discrimination function suggests a possible psychoacoustic basis in terms of relative duration differences.
On levels of description in speech research
Authors: Repp Bruno H.
Published: October 2005

Many researchers use linguistic category names (consonants, vowels, syllables) to refer to observations and measurements made in records of the acoustic speech signal. The present paper serves as a reminder that linguistic categories are abstract and have no physical properties, and that, therefore, their physical correlates in the speech wave are appropriately described in acoustic terms only.
Perceptual dimension of openness in vowels
Authors: Traunmüller Hartmut
Published: October 2005

The role of intrinsic factors determining perceived degree of vowel openness was examined. In order to determine the role of F1 and F0, one-formant vowels, covering a wide range of fundamental and formant frequencies, were identified by 23 subjects who were native speakers of a Bavarian dialect in which five degrees of openness occur distinctively. The significance of intrinsic factors other than F1 and F0 was also studied using synthetic versions of natural vowels with F1 and/or F0 systematically displaced in frequency. It was found that, generally, the tonality distance between F1 and F0 is decisive for openness, while the higher formants contribute marginally. It was further found that the distance between widely spaced formants, as between F2 and F1 in front vowels, is not crucial for vowel identification. The results are evaluated in terms of a psychoacoustic model of identification by pattern matching. The model incorporates two basic assumptions. First, a certain pattern of excitation along the basilar membrane is recognized as a given feature regardless of position along the membrane. Second, there is an integration band with a width of 3 Bark effective in spectrum envelope recognition.
Note on analysis of acoustic data from hexagonal monocrystals of unknown orientation
Authors: Gammon P. H. , Kiefte K. , Clouter M. J. , Denner W. W.
Published: October 2005

A method for determining the full set of five elastic moduli for a crystalline medium of hexagonal symmetry is described. The method utilizes acoustic velocity data obtained in monocrystals without knowledge of the orientation of the crystallographic axes. It is particularly applicable to the determination of elastic constants by Brillouin spectroscopy in polycrystalline samples.
Time domain integral equation solution for acoustic scattering from fluid targets
Authors: Bennett C. Leonard , Mieras Harry
Published: October 2005

The responses of fluid targets are computed using space–time integral equations formulated in the time domain. The incident pressure wave is a ’’smoothed-impulse’’ with a Gaussian shaped time dependence whose width is of the order of a target dimension. A space–time integral equation for the pressure field on the outside of the target surface and a space–time integral equation for the pressure field on the inside of the target surface are solved simultaneously for the pressure and the pressure gradient by stepping on in time and making use of the boundary conditions (continuity of pressure and displacement). The farfield is then computed from these source fields. The technique is applicable to targets of arbitrary contour and is demonstrated for a sphere and right circular cylinder at various angles of incidence. Fluid targets support interior compression waves; sound-hard and sound-soft targets are treated as limiting cases of this formulation. The technique has been verified for the case of a sphere by comparison with the response computed by classical expansions.
Energy transmission into shadow zone by rough surface boundary wave
Authors: Tolstoy I.
Published: October 2005

Given a rough surface characterized by roughness elements of size d and spacing h, then, for a source on or near this surface and kh<1, Biot-type boundary conditions predict the existence of a subsonic boundary wave which is first order in kd—a prediction which has been verified experimentally in detail for the case of a rough rigid wall and a homogeneous fluid. This paper examines the case of a stratified fluid in contact with a rough surface. It is shown that, for a sound velocity decreasing away from the surface—i.e., under shadow-zone conditions for a source on the surface—this boundary wave is attenuated; in the farfield it behaves like r−1/2exp(ikr)exp(−δBr). The attenuation is due to a tunneling effect. The standard acoustic (volume) wave diffracted field is, under the same conditions, represented by a sum of terms r−1/2exp(ikr)exp(−δmr). It is demonstrated that, for many cases of interest in ocean acoustics, δB<δ1 where δ1 corresponds to the least attenuated of the diffraction terms. The surface roughness boundary wave can then transmit substantially more energy into the shadow zone than is allowed for by ordinary diffraction effects. Under certain conditions its amplitude will even exceed that of a direct acoustic arrival in the absence of a sound velocity gradient—i.e., near a rough surface the shadow-zone effect can be more than offset by the roughness boundary mode.
Formulae for calculating the psychoacoustical excitation level of aural difference tones measured by the cancellation method
Authors: Zwicker E.
Published: October 2005

Data from the literature on the (f2-f1)- and (2f1-f2)- difference tones produced in the human ear and measured with the method of cancellation are averaged. They are used to formulate analytical equations with which the level of the two difference tones can be calculated and entered in models using masking or psychoacoustical excitation patterns.
Modeling the judgment of vowel quality differences
Authors: Bladon R. A. W. , Lindblom Björn
Published: October 2005

The hypothesis of this study is that the auditory cues relevant to listeners’ judgment of vowel quality are a spectral representation of loudness density versus pitch. A model is described that generates such patterns for steady-state vowels. In addition to the nonlinear transformations underlying the loudness density and pitch scales, it incorporates experimentally established characteristics associated with frequency resolution and masking, such as the critical band concept. This model is combined with a measure of auditory perceptual distance which, operating on pairs of vowels, treats each stimulus representation as a single spectral shape. In order to test the distance metric and the model, experimental data were gathered from listeners’ numerical estimates of quality differences between stimulus pairs which compared four-formant and two-formant vowels. The correlation between experimental and theoretical results was 0.89. We interpret this value to indicate that the present definition of auditory cue and auditory distance can be said to account for the experimental behavior of our listeners only in a rather gross fashion. On the other hand, the theory was developed on the basis of rather conservative assumptions about the nature of auditory cues. For instance, the model ignores the possibility of temporal coding and certain nonlinear effects, and it does not pay special attention to spectral peaks. Seen in that light, the agreement between observed and predicted auditory distance is remarkably good.
Jaw-muscle activity during speech with the mandible fixed
Authors: Folkins John W. , Zimmermann Gerald N.
Published: October 2005

Electromyographic recordings were made from the anterior temporalis, masseter, medial pterygoid, and lateral pterygoid muscles in four normal adult subjects. Discrete bursts of activity occurred in these muscles even during speech with the jaw prevented from moving by placement of a bite block between upper and lower molars. The bursts of muscle activity with the bite block were similar in frequency of occurence, time of peak activity, and magnitude to the activity observed with the jaw free to move. A motor control system that employs a central simulation process to coordinate the lips and tongue with the jaw is not necessarily consistent with this finding. An efficient central simulation process might be expected to eliminate the discrete jaw-muscle activity with the jaw fixed as well as producing correct responses in the lips and tongue. These data are more consistent with a motor control system employing lower-level neural mechanisms to coordinate articulatory movements.
Hybrid adaptive procedure for estimation of psychometric functions
Authors: Hall J. L.
Published: October 2005

Adaptive psychophysical procedures that have been described in the literature generally fall into one of two categories. (1) Simple procedures, such as UDTR and PEST, can be implemented without an on-line computer. The decision to change testing level is based on the outcome of the few most recent trials, and the final estimate of threshold is given by the final testing level or the average of a few testing levels. (2) ’’Maximum likelihood’’ methods require an on-line computer. A parametric form of the psychometric function is assumed, and after each trial a maximum-likelihood estimate of the parameters of the psychometric function is made on the basis of all preceding trials. This estimate is used to set the next testing level and to estimate threshold. We describe here a hybrid procedure, in which testing levels are determined by PEST and the final estimate of threshold is made by fitting an assumed psychometric function to all preceding trials. The PEST rules were tuned to yield results that were accurate and insensitive to errors in initial estimates of the psychometric function. These parameters differ from those that yield optimum results with classical PEST. Results of computer simulations and of experiments with human subjects are presented.