bluuebunny/crossref_metadata_2025 huggingface dataset:
Sound wave propagation in a viscoelastic fluid with coupled chemical reactions
Authors: Margulies Timothy S. , Schwarz W. H.
Published: October 2005

The classical viscothermal problem of forced, infinitesimal, planar acoustic wave propagation in a single-component Newtonian fluid is extended to a viscoelastic fluid with coupled chemical reactions. The response of the fluid is represented by Noll's simple-fluid theory which incorporates the memory of the material. In addition, the treatment accounts for multiple-step independent chemical reactions. The attenuation and dispersion of the sound wave are determined by solving the linearized (first-order) equations of mass, linear momentum, energy, and chemical kinetics. General results for the complex propagation coefficient, χ = −(α + iω/c), were obtained in the form of a biquadratic characteristic equation. α is the attenuation coefficient, c is the phase speed of the progressive wave, and ω is the angular frequency. The theory has been applied to interpret measurements reported on cyclohexanol [D. A. Rasulmukhamedova, P. K. Khabibullaev, and M. G. Khaliulin, Sov. Phys. Acoust. 22, 422–426 (1976)] over a range of frequencies.
Acoustic wave propagation in anisotropic materials
Authors: Margulies Timothy S. , Schwarz W. H.
Published: October 2005

In modeling the behavior of a class of anisotropic materials each material point is viewed as having microstructure; in particular, a vector (sometimes referred to as a director) parallel with the average molecular alignment. Anisotropic constitutive relations were derived by Leslie and Ericksen from principles of continuum mechanics and used in the viscothermal acoustic analysis of forced plane sound wave propagation in nematic liquid crystals. The linearized equations for the balance of mass, linear momentum, and energy were solved exactly. General results are obtained for the absorption and dispersion of the progressive wave as a function of frequency, in terms of a biquadratic characteristic equation for χ, the complex propagation constant, which accounts for absorption and dispersion. High- and low-frequency expansions have been examined to interpret the contribution of various phenomena separately. For the cases of low frequency and no heat conduction, the absorption results (including angular dependence of the director relative to the wave vector) agree with those of S. E. Monroe, Jr., G. C. Wetsel, Jr., M. R. Woodard, and B. A. Lowry [J. Chem. Phys. 63, 5139–5144 (1975)].
Pseudo-extinction of light as a method for detecting acoustically induced shape oscillations of drops levitated in air
Authors: Marston Philip L. , Trinh Eugene H.
Published: October 2005

A novel technique was demonstrated for detecting small amplitude quadrupole shape oscillations of liquid drops acoustically levitated in air. The technique is somewhat insensitive to drop location and environmental factors and should be applicable to drops of melted alloys. The detection method is based on the extinction paradox which states that the power removed from a light beam of irradiance I, by a drop of cross-sectional area A, is ≃2AI. Power ≃AI is reflected, refracted, or absorbed by the drop while a power ≃AI goes into the near-forward optical diffraction lobes. The power in these lobes, together with the direct beam, were collected by a lens and photocell. Reflection, refraction, or absorption by the drop extinguish the collected power P by roughly AI. Shape oscillations cause A. and hence P. to oscillate. Shape oscillations were driven by modulating the ultrasonic radiation pressure [P. L. Marston, J. Acoust. Soc. Am. 67, 15–26 (1980)]. The response functions of mm diameter water drops were measured for a swept modulation frequency. The quadrupole-resonance maximum was observed. [P. Marston was supported in part by JPL and by an M. J. Murdock Charitable Trust Grant of Research Corporation.]
Ultrasonic studies of polyethylene oxide-water mixtures
Authors: Barrett-Gültepe M. A. , Gültepe M. E. , McCarthy J. L. , Yeager E. B.
Published: October 2005

Apparent specific compressibility βapp, apparent specific volume φv, and shear viscosity measurements on aqueous solutions of polyethylene glycol (PEG) of 600 average molecular weight have indicated that two water molecules are relatively strongly bound to each ether oxygen. The ultrasonic velocity (2 MHz) versus concentration plot passes through a maximum at a PEG/H2O mole ratio of 1:2. Other work provides evidence that this hydration causes the molecule to take on a helical conformation via a hydrogen bond. The strong decrease of βapp and φv of the PEG with the addition of H2O up to two hydration molecules shows that these water molecules are strongly bound. A further decrease of βapp occurs with the addition of more water, but shows a weaker interaction and no further decrease in φv. Similar experiments were made on aqueous A-B-A type block copolymer, the moiety A being polyethylene glycol, but of chain length too short to form the helical structure. There is still an indication of a feature at the 1:2 hydration point, but not so sharply defined as with the PEG. [Work supported by ONR.]
Spectral characteristics of turbulent pressure fields
Authors: Clark Joseph A. , Stefanowicz Robert
Published: October 2005

Wall pressure fluctuations associated with equilibrium turbulent boundary layer air flow have been measured in two anechoic flow facilities over a range of flow rates. The pressure field was probed with arrays of microphones. The multichannel signal data from the microphones was synchronously digitized and digitally processed to resolve the dependence of the turbulent pressure field on both (temporal) frequency and (spatial) wavenumber. Spectral estimates of the wall pressure field around the convective ridge and in the low-wavenumber region will be presented. Contributions of observed coherent pressure structures to the spectral estimates will be discussed. [Research sponsored by ONR.]
Auditory processes related to the perception of language
Authors: Pribram Karl H.
Published: October 2005

The issues I wish to address relate auditory processes such as the perception of natural languages and of music to what is known about the anatomy and physiology of central neural auditory systems. For example, what type of mechanisms would allow the encoding of the syllabic structure of sentences? In order to address these and similar issues I will discuss psychological data on speech and language perception and physiological data from the auditory, visual, and motor systems on the encoding of language and its components. Work performed in my laboratory on cortical auditory representations and on the use of noise as signal (as interpreted by Wiener analysis) will also be presented. Two-dimensional Fourier time series, and Cepstrum analytic procedures will be discussed in an effort to produce a neural model of sufficient richness to account for the complex auditory processing of biologically significant sounds.
Intensity patterns in a fluid loading a vibrating plate
Authors: Waterhouse Richard V. , Archibald Frank S.
Published: October 2005

At the last meeting [R. V. Waterhouse, J. Acoust. Soc. Am. Suppl. 1 76, S66 (1984)], charts were given of the pressure field in a fluid loading an elastic plate, in the vicinity of a fixed point on which rectilinear waves are incident. Here, charts are presented which show the intensity vectors at many points in the above field. Each vector shows the amplitude and direction of the local power flow at a point. For comparison, intensity charts are also given for the fields produced by rectilinear plate waves alone, and by point-driven plate waves alone. To obtain the intensity values, the velocity components at each field point have to be calculated. As the pressure field is known numerically, but not analytically, the velocity components are obtained by calculating the gradients of the pressure field in the directions of the coordinates.
Simple low-frequency model for response of compliant coatings
Authors: Kalnins Arturs , Evrensel Cahit A.
Published: October 2005

Given is a thin, compliant coating, perfectly bonded to a rigid base. It is desired to find the impedance of the coating at its free surface with respect to two-dimensional, harmonic waves. In practical applications, the coating can serve as a flexible boundary that supports some action in the adjoining medium, i.e., acoustic waves or waves in fluid flow. The exact continuum model of the coating is that of viscoelasticity [M. Pierucci, J. Acoust. Soc. Am. 61, 965–971 (1977); M. Gad-el-Hak et al., J. Fluid Mech. 140, 257–280 (1984)]. In many applications, the solution in the adjoining medium is very complicated, and the evaluation of the surface impedance must be carried out many times. Sometimes an oversimplified replacement of the coating is used, such as that of a membrane [T. B. Benjamin, J. Fluid Mech. 9, 513–532 (1960)], which has response characteristics completely different from those that are given by the surface impedance of the coating. The objective of this paper is to show that a simple one-degree-of-freedom model can be constructed, as simple as that of the membrane, which still retains the main response characteristics of a solid coating, or of a stack of composite coatings. This simple model is valid for cases in which the response is dominated by the lowest frequency mode of the coating. Detailed results are given for the determination of the parameters of the model. As an example, the fluid-solid interaction problem, considered by Gad-el-Hak et al., is solved and shown that the results of the simple model and those of viscoelasticity are almost the same. [This was supported by ONR Grant N00014-81-0398.]
The acoustic radiation from excited bilaminar composite plates
Authors: Joung Il-Bok , Hayek Sabih I.
Published: October 2005

By using a new approximate model of the dynamic response of a bilaminar composite plate, the reflection and transmission coefficients of acoustic plane waves have been obtained for single thickness plates and bilaminar composite plates. Also, the farfield acoustic pressure directivity functions were computed for a single thickness plate and bilaminar composite plates which are excited by either a normal line force or a shear line force. Peaks in the radiated acoustic pressure are shown to be due to the flexural and thickness shear modes of the Timoshenko-Mindlin thick plate theory, and two new coupled modes of vibration (symmetric extensional and symmetric thickness stretch modes) for the single plate and two additional modes of thickness stretch and shear modes for bilaminar composite plates. In the high frequency region, it was found that the radiated acoustic pressure excited by a normal line force is mainly controlled by the flexural and extension modes but controlled by the thickness shear mode for a shear line source, respectively. The influence of damping in one or both layers of a bilaminar composite plate was also investigated.
Acoustic radiation from doubly periodic, ring-supported, fluid-loaded, circular cylindrical shells for different types of mechanical drives
Authors: Hallander J. E. , Burroughs C. B.
Published: October 2005

The farfield acoustic radiation from a doubly periodic, ring-supported, fluid-loaded, circular cylindrical shell is computed for moment and longitudinal mechanical drives. The shell model used by C. B. Burroughs [J. Acoust. Soc. Am. 75, 715–722 (1984)] to compute the acoustic radiation for a radial point drive is employed in this effort. The rings interact with the shell only through normal forces. The model includes the effect of fluid loading and interaction between ring supports. For a large cylinder radius, predictions are compared to published results for a point-driven doubly periodic line supported plate and a moment-driven unsupported plate. Predictions of the farfield acoustic radiation from the ring-supported cylinder for moment and longitudinal drives are compared to predictions for the radial-driven cylinder. Characteristics of the acoustic radiation are examined by example and some physical interpretation of significant features are offered.
Consonant identification time depends on the length of the following vowel
Authors: Diehl Randy L. , Kluender Keith R. , Foss Donald J. , Gernsbacher Morton Ann , Parker Ellen M.
Published: October 2005

Listeners were presented a randomized list of /bVs/, /dVs/, and /gVs/ syllables produced by two male talkers and were instructed to press a response key immediately upon recognizing a particular initial stop consonant. Three groups of 12 subjects were monitored for /b/, /d/, and /g/, respectively. The test syllables contained 10 English monophthongs varying substantially in intrinsic duration. Reaction times to the initial consonants correlated positively with the duration of the following vowels. For both talkers' syllables, this correlation was higher for initial /d/ and /g/ (with r values ranging from 0.41–0.67) than for initial /b/ (with r values ranging from 0.28–0.39). These results support the view that consonant recognition is vowel dependent and, specifically, that a certain proportion of the vowel formant trajectory must be processed before consonants can be reliably decoded. [Work supported by NICHHD.]
Temporal acuity for speech and nonspeech sounds: The role of stimulus uncertainty
Authors: Watson C. S. , Kewley-Port D. , Foyle D. C.
Published: October 2005

Previous research has demonstrated that the discrimination of stop consonants differing in VOT is categorical (nonmonotonic) in high-uncertainty tasks such as the ABX paradigm, but may become less categorical as the level of task uncertainty is decreased. In particular, Sachs and Grant [J. Acoust. Soc. Am. Suppl. 1 60, S91 (1976)] reported that the perception of a /ga-ka/ continuum became monotonic after considerable training in a low-uncertainty, same-different task. Four subjects participated in a replication of the Sachs and Grant experiments with a /ba-pa/ continuum. Results were similar to Sachs and Grants's and indicated that in the lowest uncertainty task VOT discrimination followed Weber's Law. An analogous set of experiments were carried out for somewhat simpler stimuli, following Miller et al. [J. Acoust. Soc. Am. 60, 410–417 (1976)]. These stimuli were digitally generated as a bandpassed noise followed by a buzz. The duration of the noise preceding the buzz varied in the same manner as the VOT continuum. Results were essentially the same as those obtained for VOT, demonstrating that the locus of categorical boundaries on these continua cannot be determined by local maxima in auditory acuity, [Supported by NINCDS and AFOSR.]
Perception of word-final voicing in two sentence contexts
Authors: Luce Paul A. , Charles-Luce Jan
Published: October 2005

Stressed syllables produced before major syntactic boundaries typically exhibit a marked lengthening, suggesting that listeners may have expectations regarding the relative length of syllables occurring immediately before a major syntactic boundary. We investigated the possible consequences of such expectations for the perception of word-final stop voicing, which may be cued by vowel and/or closure duration. We examined labeling performance for two continua of synthetic stop-vowel-stop words varying in vowel and closure duration. These continua were embedded in synthetic, monotone sentences in which the target stimuli occurred either at the end of an initial subordinate clause or one word before a clause boundary. For half of stimuli, a pause occurred at the boundary; for the other half, no pause occurred. Expectation of phrase-final lengthening produced a large effect on labeling performance, but only when a pause occurred at the clause boundary. The implications of these findings for perception of voicing as a function of syntactic and phonetic context will be discussed. [Supported by NIH grant no. NS-12179 to Indiana University.]
Quantitative potential for suspended particulate measurement by acoustic backscattering
Authors: Anderson Aubrey L.
Published: October 2005

Since the beginning of their use for water depth measurement, profiling acoustic echo sounders have provided evidence of midwater scatterers. Over the last decade, acoustic backscattering measurements have received increased attention for their potential in qualitative indication of suspended particulate distribution and internal water motion. In this paper, results are presented for an examination of the potential of such measurements for quantitative assessment of suspended material. While it is possible to go beyond simple qualitative description, practical limitations to quantitative measurements exist for realistic ranges of values for particulate and acoustic system parameters.
Influence of bottom refractions on the propagation of underwater sound
Authors: Miller John , Nagl Anton , Überall H.
Published: October 2005

Experimental measurements [J. S. Hanna, J. Acoust. Soc. Am. 53, 1686–1690 (1973); R. E. Christensen, J. A. Frank, and W. H. Geddes, J. Acoust. Soc. Am. 57, 1421–1426 (1975)] of the transmission loss of underwater sound propagating over an ocean bottom containing unconsolidated sediments have presented evidence on the presence of bottom-reflected energy being returned into the water column. The bottom refractions manifest themselves either via their pulse arrival times, or via interference effects in the transmission loss. In a previous study [A. Nagl, H. Überall, A. J. Hang, and G. L. Zarur, J. Acoust. Soc. Am. 63, 739–749 (1978)], we have devised a normal-mode program of underwater sound propagation containing water layers of linear velocity gradients. This program has been extended to a bottom containing unconsolidated sediment layers of different densities and velocity gradients, and shown to reproduce bottom-refracted fields interfering with reflected sound. The interference minima can be used to determine the sound speeds and their gradients in the bottom layers. [Supported by the Office of Naval Research.]
How to use noise standards and what new standards are needed
Authors: Lang William W.
Published: October 2005

The ISO 3740 series of basic standards for the determination of the sound power levels of stationary noise sources was issued by the International Organization for Standardization during the 1970s. American National Standards based on the ISO 3740 series have now been completed. These measurement standards have been adopted by several industries, including the manufacturers of computers and business equipment whose test code is continuously updated to reflect improvements in instrumentation and measurement methodology. Two important problems currently being addressed are the quantitative assessment of prominent discrete tones and the characterization of impulsive noise. The new standards being developed by the computer and business equipment industry are discussed with reference to current national and international requirements.
Reciprocal acoustic transmissions for monitoring ocean currents: Beamforming and inversion
Authors: Howe Bruce M. , Worcester Peter F. , Spindel Robert C.
Published: October 2005

A reciprocal transmission experiment with a 300-km range was conducted in August 1983 to the west of Bermuda. Since sound traveling with a current travels faster than sound against a current, one can infer ocean velocities from differential travel times along the same path. Beamforming using data from sparse, four-hydrophone arrays (one on each mooring) has been done to raise the signal to noise ratio, therefore obtaining better travel time estimates, and to determine ray arrival angles. The practical aspects of doing this with real data are discussed. A linear inversion technique is used to obtain velocity information from the differential travel times. The unknown ocean current structure in the plane of the transceiver pair is modeled using a finite number of parameters u(x,z) = Σj=0nβj(x)Fju(z), where Fju(z) are the quasigeostrophic current modes in the vertical and the spatially varying coefficient is assumed to consist of a mean, a constant gradient, and a small number of sinusoidal components. The generalized inverse is constructed from the data using a singular-value decomposition of the matrix that relates the model parameters and the data. In all cases of interest the inverse problem is underdetermined, yielding nonunique solutions.
Long-range nonlinear propagation of explosive waveforms in the ocean
Authors: Morfey C. L. , Estes J. M.
Published: October 2005

The propagation of idealized model waveforms, representative of underwater explosions measured at moderate distances (particle Mach number ≃0.06), has been simulated numerically out to large distances in an idealized uniform ocean. Besides chemical relaxation, the calculation procedure includes nonlinear waveform distortion and thermoviscous dissipation at shocks; these nonlinear phenomena are described using the weak-shock approximation. Results from the uncorrected weak-shock model, which omits chemical relaxation effects, are known to deviate appreciably from long-range measurements [P. H. Rogers, J. Acoust. Soc. Am. 62, 1412–1419 (1977)]; the discrepancy is explained by showing, with the aid of the present model, that initial waveforms having different time scales exhibit markedly different long-range behaviors. Specific waveform properties examined include the peak pressure, decay time constant, positive-phase impulse, and shock rise time. Reasonable agreement is demonstrated between model predictions and long-range measurements in the ocean, as represented by empirical scaling laws. [Work supported in part by ONR.]
Time domain approach to the propagation of nonlinear acoustic pulses near caustics
Authors: Buckley Richard
Published: October 2005

Nonlinear acoustic ray tracing in the ocean fails whenever a wave front converges to a caustic of focus, and neighboring rays intersect. It is the purpose of this paper to construct a numerical algorithm for dealing with propagation of large amplitude pulses in the neighborhood of a caustic. A time-straining transformation of the nonlinear acoustic equation is introduced that enables a perturbation expansion of the pressure in powers of signal strength to be attempted. An essential ingredient of the procedure is the knowledge of the solution of the corresponding linearized problem. An efficient procedure for calculating this for incident pulses of N waveform of arbitrary two-dimensional wave front geometry is described. The corresponding calculation of the nonlinear time straining is also presented. The procedure could readily be adapted to pulses of more general shape. [Work done in collaboration with Applied Research Laboratories, University of Texas at Austin, and supported by ONR.]
Response measurements for two building structures excited by noise from a large horizontal axis wind turbine generator
Authors: Hubbard Harvey H. , Shepherd Kevin P.
Published: October 2005

Window and wall acceleration measurements and interior noise measurements were made for two different building structures during excitation by noise from the WTS-4 horizontal axis wind turbine generator operating in a normal power generation mode. Wind turbine noise input pulses resulted in acceleration pulses for the wall and window elements of the two test buildings. Response spectra suggest that natural vibration modes of the structures are excited. Responses of a house trailer were substantially greater than those for a building of sturdier construction. Peak acceleration values correlate well with similar data for houses excited by flyover noise from commercial and military airplanes and helicopters, and sonic booms from supersonic aircraft. Interior noise spectra have peaks at frequencies corresponding to structural vibration modes and roomstanding waves; the levels for particular frequencies and locations can be higher than the outside levels.
Acoustic chaos
Authors: Lauterborn Werner
Published: October 2005

Acoustic cavitation has been found to belong to the class of deterministically chaotic systems [W. Lauterborn and E. Cramer, Phys. Rev. Lett. 47, 1445 (1981); W. Lauterborn and E. Suchla, Phys. Rev. Lett. 53, 2304 (1984)]. Experiments are described in further support of this view by constructing phase spaces from measured data and by determining the fractal dimension of the strange attractors found. As a model of acoustic chaos, a driven spherical cavitation bubble is suggested. This model has been investigated earlier in a simple version [W. Lauterborn, J. Acoust. Soc. Am. 59, 283–293 (1976)]. New results will be given on period-doubling cascades to chaos and on the bifurcation superstructure resulting from the nonlinear resonances.
Cavitation from short acoustic pulses
Authors: Fowlkes S. B. , Crum Lawrence A.
Published: October 2005

It has recently been predicted [H. G. Flynn, J. Acoust. Soc. Am. 72, 1926–1932 (1982)] that short, microsecond bursts of ultrasound could produce transient cavitation. We wish to report an experimental verification of this prediction. Using chemiluminescence as a cavitation indicator, we have observed light emissions indicating cavitation at a threshold of approximately 2.0 MPa for a pulse width of 1.0 μs at a frequency of 1.0 MHz and a duty cycle of 1:10. A description of the apparatus and a report on our latest results will be given. [Supported in part by the NSF and the FDA.]
Demonstrations of nonlinear oscillators and solitons
Authors: Keolian Robert , Wu Junru , Rudnick Isadore
Published: October 2005

We will demonstrate the peculiar behavior of nonlinear oscillations with a collection of experiments: (1) A stretched rubber band, driven by a loudspeaker, exhibits hysteresis due to its bent resonance curve. (2) A doubly bent resonance curve and hysteresis are exhibited by a parametrically driven pendulum bouncing against stops. (3) Subharmonics can be heard when a loudspeaker, laid on its back, causes a pencil to bounce. (4) A hanging chain undergoes quasiperiodically modulated vibrations, where the modulations have a frequency independent of that of the drive. (5) A pendulum, free to rotate 360°, crosses the transition to deterministic chaos when driven with the proper oscillating torque. (6) Two metronomes on the same platform, initially ticking independently, pull each other into synchronism and phase lock, as seen by Christian Huygens in 1665. (7) A parametrically driven rigid pendulum will defy gravity by standing on end and oscillating upside down. (8) We will show the nonpropagating soliton, seen by the authors in a trough of water [Phys. Rev. Lett. 52, 1421 (1984)], and two of these solitons oscillating about each other. [Work supported by ONR.]
Pitch matching versus frequency discrimination for short tones of equal or unequal duration
Authors: Hartmann W. M. , Packard Thomas N. , Rakerd Brad
Published: October 2005

The standard deviation of the distribution of matching frequencies in a two-interval pitch matching experiment and the width of the psychometric function in a two-interval frequency discrimination experiment both measure uncertainties in the perception of pitch. We compared uncertainties as measured by these two methods for tones of short duration, using all nine pairings of 12, 25, and 50 ms, at nominal frequencies of 200, 342, 584, and 1000 Hz. We found that the two experiments gave qualitatively different results. In frequency discrimination, the uncertainty decreased as the duration of either the standard or the comparison tone increased, as expected from statistical decision theory in one dimension. In pitch matching, the uncertainty function had local minima whenever the standard and comparison tones had equal duration. To explain this dichotomy we suggest that a pitch matching experiment permits a multidimensional comparison of two tones, but that a frequency discrimination experiment forces a comparison along a single perceptual dimension. [Work supported by the NIH.]
On the effect of amplitude envelopes on the pitch of short sine wave tones
Authors: Rossing T. D. , Houtsma A. J. M.
Published: October 2005

It has been shown that the perceived pitch of a short exponentially decaying sine tone is judged higher than the pitch of a gated sine tone of the same frequency and energy [W. M. Hartmann, J. Acoust. Soc. Am. 63, 1105–1113 (1978)]. Hartmann's experiment was carried out over a 3-oct range, at one intensity (89 dB SPL for the gated tone) and one exponential decay rate (1 dB/ms). In the present study pitch matches were made between short sine tones of exponential and rectangular envelopes by four subjects, where frequency varied over four octaves, reference intensity between 70 and 100 dB SPL, and exponential decay rate between 0.5 and 8.0 dB/ms. The pitch shift effect reported by Hartmann was clearly reproduced, and our data at 90 dB SPL and 1-dB/ms decay rate agree well with his data. Our data show further that the frequency difference for equal pitch is adequately described by the relation Δf = K log f, and that Δf grows monotonically both with exponential decay rate and with intensity. The intensity dependence is quite robust and suggests that linear mechanisms such as time-variant spectral transformation or the Huggins phase principle proposed by Hartmann cannot account for the phenomenon. [Work supported by a grant from the Netherlands Organization for the Advancement of Pure Research (ZWO).]
Impaired pitch matching for different waveforms after right hemisphere damage
Authors: Sidtis John J.
Published: October 2005

Studies of dichotic pitch discrimination in normal and neurologically impaired subjects have suggested that the nondominant hemisphere plays a significant role in complex pitch perception. However, despite the fact that pitch deficits can typically be demonstrated in patients with right hemisphere damage, such patients rarely report gross difficulties with functions that use pitch information, suggesting that some capacity for this process is spared. To test this, a series of pitch matching tests were administered to a 61-year-old subject who suffered a right hemisphere stroke, and was found to have normal speech but impaired pitch discrimination on dichotic testing. The frequency of one function generator was controlled by the subject and the frequency of a second generator that produced the target was controlled by the experimenter. Tones were presented continuously at 60 dBA, and the subject was free to alternate between the target and matching tones. Four conditions were tested: sine waves were matched, square waves were matched, sine waves were matched to square waves, and square waves were matched to sine waves. Mean accuracies for sine and square wave matches were 0.01 and 0.34 semitones, respectively. In contrast, matches between wave types ranged from 6.43–17.33 semitones. These results suggest that different types of pitch processing may be dissociable after focal brain damage. [Work supported by NIH.]
Within-ear and across-ear identification of complex sounds
Authors: Pollack Irwin
Published: October 2005

The two ears of a listener are not perfectly matched. How does this influence the accuracy of identification of complex sounds? Random waveforms, with and without periodic replication, were presented to listeners over earphones. The listener's task was to select one of two matching signals which more nearly matched a target signal. When all signals shared the same periodicity, within-ear signal identification was substantially superior to across-ear signal identification. Robust interaural effects were observed over a wide range of signal durations and signal periodicities (including nonperiodic signals), under different conditions of signal uncertainty, under different sets of instructions, and with different sets of earphones. Monaural-binaural comparisons yield results intermediate with within-ear and across-ear comparisons. Weaker interaural effects are observed when the matching signals were of different periodicity. [Work supported by NSF.]
Age-related changes in auditory temporal processing
Authors: Robin Donald A. , Royer Fred L. , Gruhn Joseph J.
Published: October 2005

Age-related changes in auditory temporal processing were investigated using a two-tone flutter-fusion paradigm. Ten elderly and ten young subjects (mean age 71.3 and 22.2 years, respectively) listened to pure-tone pairs at six discrete interstimulus intervals (ISIs). The duration of the second tone (T2) was held constant at 100 ms. The duration of the first tone (T1) was variable. Subjects were instructed to adjust the duration of T1 at each ISI until they perceived flutter or fusion. In both groups, when critical T1 duration was plotted as a function of ISI, the curve was best described by a negative exponential equation. Elderly subjects demonstrated higher critical T1 durations and thus their curve was shifted to the right when compared to the young group. These results are similar to those found in flutter-fusion experiments in vision. We hypothesize that decrements in temporal processing in elderly individuals may not be a modality specific phenomenon. Our results suggest a common underlying mechanism for temporal processing in audition and vision.
Synthesizing Japanese intonation using a downstep model
Authors: Beckman Mary E. , Pierrehumbert Janet B.
Published: October 2005

Studies of Japanese intonation have unanimously shown that fundamental frequency (F0) tends to fall during the course of an utterance. Previous synthesis systems for Japanese have all modeled this F0 trend using the single mechanism of a declining overall tonal reference line that is reset at the beginning of each utterance or major phrase. Recent research by Poser, however, suggests that a more accurate model must account for most of the F0 decline by means of “downstep,” a sudden step-like reduction of the reference line that is triggered by the accentual pattern of the preceding minor phrase [W. J. Poser, “On the mechanism of F0 downdrift in Japanese,” J. Acoust Soc. Am. Suppl. 1 74, S89 (1983)]. This paper describes a synthesis program for Japanese intonation that incorporates downstep. The program is being used to investigate the phonetic correlates of intonational phrasing and the interactions between syntactic phrasing and intonation. A demonstration tape will be played to illustrate the synthesis program.
Vowel intrinsic pitch influences the perception of intonational prominence
Authors: Silverman Kim
Published: October 2005

The relative prominence of accented syllables in a sentence depends on the relative heights of the associated F0 peaks in the intonation contour. An experiment was conducted to investigate whether it also depends on the associated vowel quality. /i:/ and /a:/ vowels were spliced into frame sentences to yield pairs such as “We peeked before parking” / “We parked before peeking,” with intonational peaks in both accented syllables. Versions were resynthesized with the F0 height in the second accent varied from higher than to lower than that in the first. Listeners judged which of the two accented syllables sounded more prominent. Results suggest that F0 must be higher in /i:/ than in /a:/ for the two to sound equally prominent. By implication, a single F0 contour can convey different intonational structures if just the vowel quality varies. This implies that the mapping from F0 to linguistic prominence includes compensatory adjustment for vowel intrinsic pitch. Consequently, during speech synthesis, vowel intrinsic pitch should be included in the calculation of F0 contours to ensure accurate listener reconstruction of prosodic structure.
Fundamental frequency characteristics of black six-year-olds during conversational speech
Authors: Wheat Marcia , Hudson Amelia , Miller Creighton
Published: October 2005

The study explored the fundamental frequency characteristics of 50 male and 50 female black six-year-old children during a 2-min conversation with the investigator. The results indicated that there was no significant difference between sexes for either fundamental frequency mode or range, and that there were no significant relationships between the physical variables of height and weight and the fundamental frequency characteristics for either sex or for the group as a whole. The results of the present study will be compared to previous research that studied four- to six-year-old white children during conversational speech. In addition, clinical implications and future research needs will be discussed.
Emergency contours in Dutch intonation
Authors: Eefting Wieke
Published: October 2005

This research compared the intonation contours of speech in emergency situations to baseline data produced in a “normal” reading condition. Three other conditions were designed to elicit intonation that might occur in emergency situations. Subjects produced utterances at a fast speech rate. They also produced semantically anomalous sentences, which reduced the possibility of anticipating upcoming words, at normal and fast speech rates. The utterances were stylized into a limited number of recurrent, discrete pitch movements according to procedures used by 't Hart and Collier [J. Phonet. 3, 235–255 (1975)] to describe Dutch intonation. The intonation patterns used in emergency situations appear to represent a simpler intonation contour than that used under normal conditions. The emergency contour, which consists of a small number of variations of the most elementary “hat” patterns, is used in many different phrases and contexts. It may prove useful as the default intonation contour in speech synthesis by rule programs.
Boundaries and F0 movements in Spanish
Authors: Signorini Angela , de Manrique Ana María Borzone
Published: October 2005

The present paper aims to quantify the fall-rise movements in the F0 curves of a set of Argentine Spanish declarative sentences and the relationship between these movements and the syntactic structure of the sentences. The factors taken into account were: the steepness of the fall-rise movements, the location of the movements in relation to the accented syllables, and the location of the movements in relation to their occurrence in the utterance. Results show that there is a close relationship between the fall-rise movement, possibly signaling a boundary, and the F0 accent subcontours. It is also observed that the magnitude of the movement may be marking the presence of boundaries in degrees. In order to evaluate these results in a systematic way the top reference line was taken into consideration. This criterion proved to be effective for the present data.
Cues for lexical stress and recognition of polysyllabic words, synthesized from diphones and presented in isolation
Authors: Nooteboom Sieb G. , Doodeman Gert J.
Published: October 2005

Knowing the position of lexical stress in a polysyllabic word may considerably limit the number of lexically possible responses. Thus perceptual cues may contribute to a higher probability of correct recognition and faster recognition of words in the perception of speech of less than optimal quality. Probability correct was assessed for 30 three-syllable Dutch words, synthesized from diphones. All words were of CVCVCVC phonemic structure, containing no consonant clusters. Ten words each had initial, medial, or final lexical stress. Stress position was either not cued at all, cued by durational cues only, cued by a conspicious pitch movement, or cued by both durational and pitch cues. Each word in each condition was responded to by five listeners. Scores correct, averaged over stress position, were 66% with no stress cues, 74% with durational cues, 81% with pitch cues, and 81% with durational and pitch cues combined. The contribution of stress cues was strongest for words with initial stress (from 54%–76%), and minimal for words with final stress (from 80%–88%). To investigate the effect of stress cues on the rapidity with which listeners tune in on the correct response, a gating-paradigm-type of experiment was performed on the same material. However, in this task errors against stress position were much more frequent, and positive effects of stress position were small.
Effect of traffic noise on the cyclical nature of sleep
Authors: Thiessen G. J.
Published: October 2005

It is well known that normal sleep, as measured by the EEG is not a uniform state but varies from shallow to deep sleep in a cyclical manner. The duration of the cycle is roughly 1.5 h. It has been suggested that disruption of these cycles can have unfavorable effects on a subject's performance during the following day [M. Herbert and R. T. Wilkinson, Proc. Mt. Congress on Noise as a Public Health Problem (1973)]. Twelve subjects slept in 60 dB of free-flowing traffic noise on 12 alternate nights while the level during the other 12 nights was the ambient level of about 32 dB. If every waking or shift to a shallow sleep level is considered to be the beginning of a new cycle, then the average number of cycles per night during the noise night is about 6% greater than during the quiet nights. If only an extended period of shallow sleep is judged to be the beginning of a new cycle, then noise has no effect on the number of cycles per night.
An experimental investigation of acoustic propagation in saturated sand with variable fluid properties
Authors: Costley Dan , Bedford A.
Published: October 2005

The Biot-Stoll theory describes the propagation of acoustic waves in a saturated, unconsolidated porous medium. The expressions for the attenuation and phase velocity derived from this theory depend explicitly on the viscosity, density, and bulk modulus of the pore fluid. An experiment has been designed to determine the dependence of attenuation and phase velocity on these properties of the pore fluid. The phase velocity and attenuation of compressional waves were measured using a mixture of water and glycerine as the interstitial fluid. A review of the experimental procedure and the results will be presented, together with comparisons with the Biot-Stoll theory. [Work supported by the Office of Naval Research.]
Acoustic response of sedimentary particles in the nearfield of high-frequency transducers
Authors: Ma Y. , Varadan V. V. , Varadan V. K.
Published: October 2005

In this paper, a procedure is described for finding the backscattered response of an elastic, solid particle in the nearfield of a high-frequency ultrasonic transducer using a T matrix to characterize the response of the scatterer itself. Numerical results are presented for spherical particles for both shaded and unshaded transducers. The particular application of interest is the monitoring of the vertical profile of sedimentary suspensions up to a meter above the abyssal ocean floor. For a 5-MHz transducer, particles at distances of less than 50 cm from the transducer are in the complicated nearfield. The backscattered acoustic response of the sediment particles in a given volume as measured by an ultrasonic transducer is directly related to the concentration and size distribution of the particles.
The character of the turbulent wall pressure spectrum at low Mach numbers
Authors: Chase David M.
Published: October 2005

Characteristics of the wave-vector-frequency spectrum of turbulent wall pressure on a smooth rigid plane at low Mach number are reviewed with emphasis on recent indications of the behavior at subconvective, including acoustic, wavenumbers. This depends essentially on the rate of decrease of velocity-product (pressure-source) cross spectra with wall distance and on the identity of the wavenumber parameter that scales this profile. Since the source thickness need not be finite uniformly in wavenumber, even the Kraichnan-Phillips hypothesis rests on no discernible general principle. Plausible source models permit a range of possible dependences in the part of the subconvective domain where K ≳ (bδ)−1, where bδ is a source-layer thickness. Though diverse wall-pressure experiments do not fully agree, indications point to a pressure spectrum roughly wave-vector-white and scale independent in that domain. This possibility is supported by a source model suggested by an irrotational contribution to spectra of (linear) fluctuating velocity. When the low-wavenumber expansion of the pressure-source relation employed in such modeling is applied with slight compressibility permitted, for the idealized planar-homogeneous boundary layer an inverse first-power singularity of the pressure spectrum occurs at the acoustic wavenumber but is removed by finiteness of extent or, with regard to the total (cf. blocked) wall pressure, by a finite wall impedance.
Features of the turbulent boundary layer pressure field on an elastic surface
Authors: Crighton D. G.
Published: October 2005

In any approach to calculation of the wall pressure spectrum of a TBL based on an inhomogeneous (Lighthill) wave equation, singularities of the spectral density arise along various lines or surfaces in (k,ω) space. These lines of surfaces correspond to the acoustic or structural dispersion relations, and the singularities may be controlled by such mechanisms as surface finiteness, dissipation in the structure or fluid, and surface compliance. This paper will examine the way in which these various mechanisms control the singularities in different regimes of the spatial and dynamical parameters involved, and will give scaling laws for the pressure spectral densities at the critical conditions in (k,ω) space. [Work supported by ONR, Code 425.]
Calculations of turbulent boundary layer pressure fluctuations transmitted into a viscoelastic layer
Authors: Ko Sung H. , Schloemer Howard H.
Published: October 2005

The objective of this paper is to develop a model for calculating the turbulent boundary layer pressure fluctuation transmitted into a layer of viscoelastic material. The theoretical model used here is a plane elastomer layer backed by a rigid plane surface. The other side of the plane surface is exposed to a turbulent flow. The transmitted flow noise received by a rectangular hydrophone embedded in the elastomer layer was calculated for various turbulent boundary layer forcing functions developed by Corcos, and by Chase. The transmitted flow noise was characterized by the frequency spectral density expressed in decibels. Wave-vector spectral densities of various turbulent wall pressures were discussed. Effects of the elastomer layer thickness, material properties and flow conditions on the transmitted noise level are presented.
Wavenumber-frequency response of periodic ring-supported, circular cylindrical shells subjected to turbulent-boundary-layer excitation
Authors: Bostian David A. , Burroughs Courtney B.
Published: October 2005

The wavenumber-frequency structural response of a fluid-loaded, periodic ring-supported, circular cylindrical shell is modeled. In the model, the ring supports are assumed to interact with the shell only through normal forces. The TBL pressure fluctuation wavenumber-frequency spectra models of Corcos [J. Fluid Mech. 18, 353–378 (1964)] and Chase [J. Sound Vib. 70, 29–67 (1980)] are used in this effort. Sums are taken over wavenumbers to obtain predictions of the average shell response to TBL excitation as a function of frequency. Bands of wavenumbers that control the shell response are identified for different frequencies and shell configurations.
Modal analysis of classical and folk guitars
Authors: Popp John , Hansen Uwe , Rossing Thomas D. , Strong William Y.
Published: October 2005

The mechanical responses of three freely supported guitars have been studied both under impulsive excitation and under excitation with a sinusoidal force [J. Popp and T. D. Rossing, J. Acoust. Soc. Am. Suppl. 1 76, S26 (1984)]. The normal modes of vibration as determined by the two different methods have been compared, and the agreement is found to be quite good. A comparison is made with the modes of vibration recorded in one of the guitars with the ribs fixed using time-average holographic interferometry.