bluuebunny/crossref_metadata_2025 huggingface dataset:
Detection and lateralization thresholds for repeated random waveforms in noise
Authors: Pollack Irwin
Published: October 2005

Interaural phase effects are reported for the lateralization and for the detection of repeated random waveforms in white noise. For lateralization, the primary component of interaural phase effects is the interaural phase of time-delayed signal and is relatively independent of the interaural phase of a nondelayed noise. In-phase signals yield substantially lower lateralization thresholds, at least for interaural delays up to 0.5–1.0 ms. This result is obtained with the following interaural noise relations: in phase, out of phase, random phase, and monaural noise. The importance of signal phase may relate to the search for moment-by-moment correlation by a binaural system with differential processing of waveform condensations and rarefactions. For detection, the primary component of interaural phase effects is related to the homophasic-antiphasic combination of signal and noise. The magnitude of the interaural phase effects is substantially smaller for wideband repeated random waveforms than reported for pure tones. The smaller interaural phase effects may relate to the difficulty of establishing lateralization cues for wideband signals in the absence of a time delay.
A theoretical model for an array of flextensional transducers
Authors: Brind Richard J.
Published: October 2005

Acoustic interaction effects can seriously degrade the performance of arrays of sonar transducers if the efficiency of the elements is high and the interelement spacing is small. An experimental array of four 300-Hz flextensional transducers was deployed in Loch Goil in Scotland to investigate these effects. Here, an equivalent circuit model for the transducers is developed and a theory for the interaction effects presented. The model is validated against the array measurements taken in Loch Goil. The theory was used to predict admittance loops and farfield beam patterns for unsteered and steered arrays with half-wavelength and quarter-wavelength element spacings. An interactive program has been written to perform these calculations on an HP45 computer. Farfield beam patterns were obtained directly with a hydrophone lowered from the surface, and were calculated from nearfield measurements. The agreement between the predictions and the measurements was very good. The interaction effects in an array with half-wavelength spacing were small. With quarter-wavelength spacing, interaction effects were severe, giving rise to a 2.5-dB reduction in transmitting voltage response and narrow frequency bands where the conductance of one of the elements was dangerously low.
Improvement of a magnetostrictive length-expander transducer by use of a grain-oriented material
Authors: Claeyssen F. , Boucher D. , Faure S.
Published: October 2005

In order to prove the ability of new magnetostrictive rare-earth-iron alloys for high-power low-frequency transmitting transducers, a first prototype of a length-expander projector had been realized in 1987. Although the active material was a random-oriented alloy (R), high-power measurement results were quite satisfactory [F. Claeyssen, J. Acoust. Soc. Am. Suppl. 1 81, S89 (1987)]. On the other hand, an active material characterization work [F. Claeyssen, J. Acoust. Soc. Am. Suppl. 1 83, S20 (1918)] has led to theoretical predictions showing the advantages of grain-oriented alloys (G.O.) compared to the random-oriented alloy. In addition to the increase of acoustical power, a lower resonance frequency and a better effective coupling factor are expected. In this paper, the theoretical improvement of a transducer due to the use of G.O. alloy is checked with the in-air and in-water measurements of the prototype transducer mounted with a G.O. material.
Finite element modeling of piezoelectric transducers including internal losses
Authors: Dubus B. , Debus J. C. , Decarpigny J. N. , Boucher D.
Published: October 2005

An actual radiating sonar transducer is always generating heat, due to internal losses and to the friction between the different parts of the structure. Thus its efficiency is lower than 1 and a temperature rise can occur. To describe these phenomena, the finite element code ATILA [Decarpigny et al., J. Acoust. Soc. Am. 78, 1499 (1985)] has been improved by including the effects of internal losses, using a complex Young's modulus for isotropic materials and complex tensors for piezoelectric ceramics. Then, electrical and thermal measurements have been performed on various sandwich transducers, at different drive levels, to determine the ceramics loss angles. Finally, the electrical impedance, transmitting voltage response, and mechanical displacement field have been computed for a multifrequency Tonpilz transducer [Boucher et al., J. Acoust. Soc. Am. Suppl. 1 80, S27 (1986)] and a ring transducer [Bossut et al., J. Acoust. Soc. Am. Suppl. 1 74, S23 (1983)] radiating in water, and the theoretical results have been compared to experimental values, showing a reasonable agreement which will be carefully discussed.
A Poisson-coupled plastic projector
Authors: McMahon G. W. , Franklin J. B.
Published: October 2005

An underwater electroacoustic projector is described in which a hollow tube of plastic is driven axially in order to excite its radial resonance by Poisson coupling. The driver is a piezoceramic stack that connects to the plastic tube via stiff metal end plates. The projector was desgined using the finite-element program MAVART to predict performance and enable a suitable selection of dimensions for an experimental model. The projector is 18 cm long, 11.4 cm in diameter, and weighs 0.7 kg. Although no well-defined resonance is exhibited, efficient operation is predicted from 2200 to 3300 Hz, with a source level up to 191 dB re: 1 μPa @ 1 m. The measured performance of the experimental unit is compared with MAVART predictions.
Finite element modeling and array interaction modeling of the ARE low-frequency flextensional transducer
Authors: Brind Richard J.
Published: October 2005

A requirement for underwater acoustic sources with higher source level and wider bandwidth at lower frequencies has, in the past 5 years, lead to interest in flextensional transducers. A low-frequency prototype has been developed, manufactured, and tested at ARE(Portland); the technology is the subject of a license agreement with industry. In this paper, finite element (FE) analyses performed in support of the prototype development using PAFEC software are described. PAFEC is a commercially available FE package with the facility to model piezoelectric materials, and exterior fluid loading by the doubly asymptotic approximation. In-air and in-water resonant frequencies are well predicted, as is the effect of hydrostatic pressure on stack prestress. The transducer is subjected to large stresses during assembly, and predictions for these have also been obtained. Problems remaining in the FE modeling, and improvements in the capabilities of PAFEC under development to overcome them, are discussed. An equivalent circuit model for an array of these flextensional transducers is described, and a comparison of admittances and farfield predictions with measurements presented.
Minimax shading of arbitrary arrays
Authors: Bordley Thomas E.
Published: October 2005

An iterative algorithm for minimizing the maximum sidelobe level of an arbitrarily shaped array over bands of frequencies and directions is presented. The approach is novel both in providing an optimal Tchebyshev solution for nonuniformly spaced, multidimensional arrays and in providing a solution over frequency bands. At each iteration, the algorithm generates a descent direction minimizing the response at the highest sidelobes. The method is applicable both to plane-wave beamforming and to matched field processing. In this presentation, the trade-offs between beamwidth, bandwidth, and sidelobe level are considered for the conventional beamformer for a variety of nonuniformly spaced arrays.
Large area sensors for active acoustic control systems
Authors: Howarth Thomas R. , Bao Xiaoqi Q. , Vatadan Vijay K. , Varadan Vasundara V.
Published: October 2005

The design and development of a composite piezoelectric polymer (PVDF) sensor for use in an active acoustic control system is presented. Large area PVDF plates are encapsulated in a polymer matrix to detect both the incident and reflected signals in an underwater pulse tube at low frequencies. These signals are amplified, phase shifted, and then used to drive an absorbing transducer to negate reflections. The results of this system are compared with earlier data [X.-Q. Bao et al., J. Acoust. Soc. Am. Suppl. 1 84, S49 (1988)] that utilized piezoceramic spherical hydrophones.
A theoretical basis for acoustic sensitivity and optimization analyses of three-dimensional radiators
Authors: Cunefare Kenneth A. , Koopmann Gary
Published: October 2005

Numerical techniques have been developed that enable acoustic sensitivity and optimization analyses to be performed on three-dimensional radiators. Sensitivity analysis of a body vibrating at a single frequency with a known normal velocity distribution indicates those areas of the surface that have the greatest influence upon the radiated power at that frequency. Regions of high sensitivity would be likely candidates for the application of damping materials or as locations for active control sources. Optimization analysis provides the optimum magnitude and phase at which to drive active cancellation sources in order to minimize the radiated power. Both techniques are based upon a discretized expression for radiated power, where surface pressure has been replaced by an expression that relates pressure to surface velocity through a transfer matrix. The transfer matrix is derived from a numerical discretization of the Helmholtz integral equation.
A new type of Gaussian ultrasonic transducer
Authors: Du Gonghuan , Ding Desheng , Gan Changming
Published: October 2005

A Gaussian ultrasonic field is known to have some advantages [G. Du and M. A. Breazeale, J. Acoust. Soc. Am. 78, 2083–2086 (1985)]. In this article, a new type of Gaussian ultrasonic transducer is presented with a curved back electrode instead of a usual plane electrode. The mathematics of design is based on an inverse approach. The theoretical result shows that the shape of the curved back electrode is dependent on the thickness of the transducer and on the Gaussian coefficient of vibration displacement on the surface of the transducer as well as on the ratio of dielectric constants of the transducer to the material of the back electrode. The inspection of displacement distribution is carried out on the surface of the transducer by using a laser interference technique. The measured results indicate good agreement with the prediction of the theory.
Characteristics of variable-reluctance transducers as underwater acoustic projectors
Authors: McLaughlin Elizabeth A. , Moffett Mark B.
Published: October 2005

Variable-reluctance projectors, because they can deliver higher forces than moving-coil projectors, have long been proposed for underwater use. Single elements are nonlinear, however, and push-pull configurations of element pairs [W. T. Harris, U. S. Pat No. 2,713,127; J. Chervenak, U. S. Pat. No. 3,725,856; G. Pida, U. S. Pat. No. 3,691,515; F. Massa, Jr., U. S. Pat. No. 3,319,220] have been used to eliminate second-order nonlinearities. Such push-pull arrangements are usually dipole radiators in nature and need to be baffled for monopole radiation. The displacement is normally limited by the gap thickness, but transverse variable reluctance devices [F. R. Abbott, U. S. Pat. Nos. 3,126,520, 3,353,040, and 3,605,080; J. Chervenak, U. S. Pat. No. 3,517,279] are not subject to this limitation and hence can produce greater displacements, albeit smaller forces, than can direct variable-reluctance transducers. The characteristics of these transverse variable-reluctance devices turn out to be similar to moving-coil projectors in many respects.
Reflection of focused sound from curved, rigid surfaces
Authors: Averkiou Michalakis A. , Hamilton Mark F.
Published: October 2005

Target geometry and orientation significantly affect the current accuracy of ultrasonic sensors used for gauging and proximity sensing [R. Hickling and S. P. Marin, J. Acoust. Soc. Am. 79, 1151 (1986)]. The reflection of focused sound from curved, rigid surfaces using Gaussian beam solutions obtained from the parabolic approximation of the wave equation has been investigated. Both the focusing of the source and the curvature of the target are modeled by quadratic phase factors. A simple closed-form solution is thus derived for the sound reflected from concave and convex targets in either axisymmetric or nonaxisymmetric configurations. The validity of the solution is restricted to cases in which the focusing gain of the source, and the curvature of nonperpendicularity of the target, are not too large. Propagation curves, beam patterns, and scattering trajectories are used to illustrate the combined effects of diffraction and target curvature on the reflected sound field. Transfer functions are obtained by comparing the received to the transmitted acoustic power for the case of a monostatic acoustic sensor. [Work supported by GM and NSF.]
Echo identification using phase information
Authors: Erdol Nurgun , Roemer Louis , Ida Nathan , Huo Ke-Sheng
Published: October 2005

The signal waveforms chosen for reflectometry often result in overlapping echo waveforms. The waveforms chosen are constrained by transducer limitations, attenuation, and resolution properties of the test medium. The extraction of echo location information can be achieved using phase information, via the maximum entropy method. The phase estimate is constructed from the power spectrum of the even components (See) of the signal and the power spectrum of the odd components (Soo) of the signal. The cosine of the phase is cos[2θ] = See(e∫ω) − Soo(e∫ω)See(e∫ω) + Soo(e∫ω). By computing the spectrum of the above relation, the echo delay td can be computed using cos[2θ(ω)[ = cos[2ω(td)] in the frequency domain. The method of analysis is presented, along with experimental verification that overlapped echoes are easily identified for a simple reflecting structure using ultrasound.
Reflection and transmission of elastic waves from a fluid/porous solid interface
Authors: Wu Kunyu , Xue Qiang , Adler Laszlo
Published: October 2005

In this paper, Biot's theory of wave propagation in a porous solid has been applied to a theoretical study of energy reflection and transmission of elastic waves at oblique incidence on an interface between fluid and fluid-saturated porous solid. For this purpose, the necessary formalism of energy equation, Poynting energy flux vector, and sound intensity of elastic wave in fluid-saturated porous solid are presented. Two general cases of mode conversion have been investigated: (i) The initial wave is incident from the fluid to the interface and generates three transmitted bulk waves in the fluid-saturated porous solid, and (ii) the initial wave is incident from the fluid-saturated porous solid to the interface and generates three reflected bulk waves in the same media. The calculated results are in agreement with the law of conservation of energy. Furthermore, the transmission of sound through a fluid-saturated porous solid plate immersed in fluid is calculated to specify the optional condition supporting a strong slow compressional wave and to interpret Plona's experimental results. [This work was supported by the U. S. Department of Energy, Basic Energy Science Grant ED-FG02-84ER45057.A0005.]
Dispersive guided waves in interface layers
Authors: Nagy Peter D. , Adler Laszlo
Published: October 2005

It was recently suggested by the authors [J. Acoust. Soc. Am. Suppl. 1 83, S78 (1988)] that guided waves in an interface layer can be used to characterize bond quality in adhesive joints. Experimental results clearly indicate that leaky guided modes of the interface layer itself are much more sensitive to most types of bond defects than the corresponding Lamb modes of the multilayered joint as a whole. Quantitative evaluation of the experimental results requires the development of an analytical technique to calculate the dispersion curves of guided waves in a solid (adhesive) layer between two solid (adherent) half-spaces. Special emphasis was placed on complex modes that are substantially attenuated by leaking into the substrates because of the relative easiness of generating and detecting them by simple experimental techniques. Differences between free and forced vibrations of the interface layer are considered, too. Experimental results are shown to be in good agreement with the calculated theoretical dispersion curves.
Acoustic scattering from an air-filled prolate cylinder
Authors: Maze G. , Lecroq F. , Izbicki J. L. , Ripoche J. , Numrich S.
Published: October 2005

The ultrasonic scattering from circular cylinders is described in numerous papers. If the insonification is perpendicular to the cylinder axis, the scattering is strongly influenced by the propagation of circumferential waves. These circumferential waves propagate either in the elastic shell, where they are the Whispering Gallery waves, or at the interface water/elastic shell, where they are the Scholte-Stoneley waves. These waves, for some frequencies called resonances, form standing waves around the cylinder. Previously, it has been shown that the resonance frequencies are functions of the cylinder diameter, the shell thickness, and the target composition. In this presentation, the influence of the curvature radius on the position and the amplitude of resonances is studied. The method of isolation and identification of resonances (MIIR) is used to plot resonance spectra of air-filled prolate cylinders. The incident ultrasonic beam perpendicular to the cylinder axis insonifies the cross section at different positions. The resonance spectra of an air-filled prolate cylinder are compared to those obtained with a circular cylinder that has the same thickness and the same circumference.
Scattering from elastic shells in time domain at coincident frequencies
Authors: Werby M. F. , Ali H.
Published: October 2005

Scattering from the submerged elastic spherical shells at the frequency at which the phase velocity of the flexural (A0) mode is approximately equal to the speed of sound in the ambient fluid is considered. This is referred to as the coincident frequency for plates, and it produces strong flexural vibrations in both plates and spherical shells. The resonances that arise for bounded objects are observed to have a fairly constant group velocity and resonance width over a broad ka region. It is shown that this is sufficient to produce a large backscattered return of a characteristic shape in the time domain. This is demonstrated for several examples.
The Rayleigh and flexural resonances for elastic solids and shells
Authors: Werby M. F. , Gaunaurd G. C.
Published: October 2005

In a comparative study, the Rayleigh (leaky Rayleigh-type) resonance and the flexural resonances for the solid and shells of thicknesses of 1% to 95% of the outer radii are calculated. It is shown that, as the shell thickness increases, the flexural resonance goes into the Rayleigh resonance at about a thickness of 60%. Further, these resonances are observed out to a ka of 500. It is also shown that thin shell theories predict the resonance shapes or the flexural modes for the thin cases, including the well-known effect of an upturn at the lower end of the frequency range.
A suitable background for elastic shells
Authors: Werby M. F.
Published: October 2005

It has been known for some time that a useful background in the description of scattering from elastic solids is the rigid scatterer. When resonances are not too strongly overlapping, then, by subtracting a rigid background, it is possible to isolate the resonance response from the elastic solid. Previously, it was reported that, for very thin shells at low frequency, a soft background was suitable and that, at very high frequencies for thicker shells, a rigid background was suitable. A suitable background for the elastic shell for all frequencies and for shells to moderate thickness is derived, and its utility is demonstrated with several examples.
The acoustic scattering by a submerged, elastic spherical shell: High-frequency limit
Authors: Hackman Roger H. , Sammelmann Gary S.
Published: October 2005

This presentation represents the third in a series devoted to the analysis of the analytic structure of the acoustic scattering amplitude of an elastic spherical shell. In previous meetings [J. Acoust. Soc. Am. Suppl. 1 83, S94 (1988); 84, S185 (1988)], a fundamentally oriented analysis of the pole structure of the scattering amplitude in the low- to mid-frequency region was presented. The most surprising result of this investigation was the demonstration that the fluid-loaded antisymmetric Lamb wave bifurcated near the frequency that the vacuum dispersion curve transitioned from a subsonic to a supersonic phase velocity. In this presentation, the previous analysis of both the behavior of the acoustic scattering amplitude of a thin spherical shell and the pole structure of the S matrix is extended to the high-frequency region (100 < ka < 1000). The appearance of behavior that has a strong analogy with that of the higher-order flat plate Lamb waves is demonstrated. In particular, the appearance of strong thickness resonances, regions of anomalous dispersion, and regions of negative group velocity analogous to those observed by Tolstoy and Usdin [J. Acoust. Soc. Am. 29, 37–42 (1957)] in their study of the dispersion properties of higher modes on a plate is discussed.
An analysis of the modes of an elastic prolate spheroid: From a spherical to cylindrical geometry
Authors: Sammelmann Gary S. , Hackman Roger H.
Published: October 2005

The acoustic scattering from a solid prolate spheroid is studied as a function of frequency and aspect ratio. The emphasis of this study is on the nature and the coupling of the elastic excitations of a solid prolate spheroid in the transition from a spherical to what is essentially a cylindrical geometry. The aspect ratio of the spheroid from the spherical limit to the almost cylindrical limit is varied. In this manner, it is possible to classify the elastic excitations of low-aspect ratio prolate spheroids in terms of the elastic modes of vibration of a sphere and to study how these modes undergo transformation to the modes of a cylinder with respect to increasing aspect ratio. A qualitative comparison of the behavior of these low-frequency elastic excitations of a prolate spheroid and their quasicylindrical mode interpretation is made.
An application of the forward-scattering theorem to elastic wave attenuation in inhomogeneous materials
Authors: Scharnhorst Kurt P. , Hackman Roger H. , Lim Raymond
Published: October 2005

The forward-scattering amplitude of two adjacent scatterers f(2) may be used to construct an effective medium theory of inhomogeneous media containing random distributions of scatterers. The amplitude f(2) may be thought of as the lowest-order approximation of the amplitude f(n), of an interacting cluster of n scatterers contributing to the formation of the coherent elastic wave. Since the elastic wave encounters all orientations of pairs, the averaged nearest-neighbor forward-scattering amplitude is studied. Specific orientations that are dictated by the dynamics of the scattering processes are also considered. The average forward-scattering amplitude is analyzed in terms of the direct σpp mode conversion, σpp, and absorption cross sections for random distributions of viscoelastic spherical scatterers in elastic matrix materials. Estimates of longitudinal wave attenuation due to these three mechanisms in specific materials are presented.
Articulatory correlates of stress clash rhythms
Authors: Beckman Mary E.
Published: October 2005

Linguistic characterizations of English stress patterns typically claim that when one stressed syllable is followed immediately by another and the rhythmic clash is not corrected by retracting the first stress to an earlier position, then the first vowel will be protracted, increasing the phonetic separation between the adjacent beats and thereby regularizing the rhythm. Acoustic studies, however, consistently show that the mean duration for the first vowel in such a stress clash is not substantially longer than that of its counterpart in an alternating stress pattern. Examination of articulatory correlates suggests an explanation for this discrepancy: Syllables in a stress clash may undergo a rhythmic reorganization of segmental gestures that can distance the first syllable's prosodic peak from the following stress without lengthening the vowel's measured duration. Displacements, durations, and peak velocities of jaw opening and closing gestures were measured for four speakers' productions of stress clash sequences Pop posed and alternating stress sequences Pop opposed. In general, the jaw opening gesture was relatively shorter and the closing gesture relatively longer in the stress clash context. If the degree of jaw opening is taken as an approximation to the sonority contour within the syllable, this result means that the prosodic peak occurred relatively earlier within the initial [pap] in Pop posed. [Work supported by the National Science Foundation under grants IRI-8617852 to Mary Beckman and IRI-8617873 to Jan Edwards.]
Effects of the mora and segmental features on word duration in Japanese
Authors: Port Robert , Hardy Jane
Published: October 2005

Word duration in Japanese is determined by number of moras when words are pronounced at a normal speaking tempo in focus position in carrier sentences [Port et al., J. Acoust. Soc. Am. 81, 1547–1585 (1987)]. Still, variation in segmental makeup has some effect on work duration. It was expected that, when out of focus position or when spoken at faster tempo, durations for words with a given number of moras would show more variation. A set of Japanese words of two, three, and four moras having various syllabic templates (e.g., tokki, tooki, etc.) was chosen. They were produced in both focus position and nonfocus position (by changing a nontarget word from sentence to sentence) at two tempos. Words with same mora length exhibited less word-to-word variation at slow tempo than fast, and less variation in the focus position than when nonfocused. To factor out segmental effects, subjects were asked to produce each sentence reiterantly by replacing each mora of the target word with ta. As expected, reiterant results showed almost no variation due to original segments and much less effect of sentence position and tempo. The results suggest that competing constraints affect Japanese timing: a mora constraint (“make all moras equal”) plus intrinsic segmental constraints (different for each segment type). Mora timing dominates at slower tempos and in focus position, but can be overpowered by constraints of intrinsic segmental duration elsewhere. [Work supported by NSF, DCR-85-18725.]
A cross linguistic contrast in the temporal compensation effect
Authors: Otake Takashi
Published: October 2005

The purpose of this investigation is to evaluate whether the temporal compensation effect in Japanese can be attributable to mora timing. It has been asserted that the temporal compensation effect has an important role in regulating a CV syllable duration in Japanese [Port et al., Phonetica 37, 235–252 (1980)]. In an earlier study [T. Otake, J. Acoust. Soc. Am. Suppl. 1 84, S97 (1988)], Arabic and Japanese were investigated under the same conditions with respect to the compensation effect, and it was found that both languages showed the same compensation effect, which may suggest that it is a universal phenomenon [Beckman, Phonetica 39, 113–135 (1982)], The experiment reported here used the method of Port et al. (1980) to test the hypothesis further by investigating other languages that belong to stress timing (English and German) and syllable timing (Spanish and French). In addition, Chinese, which does not belong to any of these timings, was investigated. Pilot results show that the temporal compensation effect reported by Port et al. (1980) can be equally observable in the above languages.
On the temporal alignment of F0 with segmental structure
Authors: Silverman Kim E. A.
Published: October 2005

Timing and F0 tend to be correlated in speech. For example, a syllable near the end of a phrase will be lengthened, and if it bears a local F0 maximum (a high pitch accent), then the peak will occur earlier in that syllable. The more the lengthening, the earlier the accent peak. However, the current experiment shows a case where F0 peaks are aligned earlier in their syllables without the expected concomitant lengthening. Two speakers recorded My _____ lives in Memphis, where the second word was Ma, Mom, Mama, Pa, Pop, or Papa, both with and without a low F0 target (corresponding to an utterance-internal prosodic boundary) after the second word. Acoustic measurements, combined with perceptual judgments, show that the low tone pushes the preceding pitch accent about 50% earlier in its syllable, with little or no lengthening of that syllable. Thus peak alignment depends on upcoming tonal events, as well as those utterance features that determine durational structure.
Evidence for levels of prosodic hierarchies in Swedish
Authors: Rauschenberg J. M.
Published: October 2005

Pierrehumbert and her colleagues have proposed a model of prosodic organization that utilizes not only types of constituents and their marker(s), but also well-defined edges. Beckman and Pierrehumbert (1986) have suggested that, in English, the phrase tone following the nuclear accent marks the right edge of an intermediate phrase (ip), giving evidence of phrasing internal to the intonational phrase (IP). Beckman and Edwards (1987) account for a final lengthening effect in English as one marker of the edge of the IP. Swedish differs from English in that sentence accent does not occur at a phrase edge. Thus, if there is a level at which there is one and only one sentence accent, utterances with single terminal junctures and multiple phrase tones must be analyzed as having one IP with multiple ip's. But there is no tonal marker for the edges of the ip's. An experiment has been constructed (in progress) to test the hypothesis that lengthening will occur at the end of the IP and, to a lesser extent, the ip, and that this might allow a determination of edges of Swedish phrasal units. Thus words at the ends of phrases should be longer than in medial position. The corpus consists of sentences, each having five accent 2 words, in six different constructions. The predictions are, specifically, (1) that the test word will be longer in sentence final position, and (2) that in tokens that show internal phrasing (as indicated by multiple phrase/sentence tones), the word will be longer where it occurs at the edge of an internal constituent than where medial to a single phrase constituent.
Relation between the features “givenness” and “accentedness” and the duration of Dutch words
Authors: Eefting Wieke
Published: October 2005

The aim of this study is to investigate whether the duration of a word in speech production is related with the information value (carrying “new” or “old” information) and with the accentedness (+ or − accent) of the word. Fowler and Housum [C. A. Fowler and J. Housum, J. Mem. Lang. 26, 489–504 (1987)] found that speakers tend to shorten words conveying old information. It has also been found, by others, that accented words have a longer duration than words that do not carry accent. Because the features new/accented and old/unaccented appear to be closely related, it is unclear which of the two features causes the differences in duration as found by Fowler and Housum. In the present study, it is attempted to sort out the effects of accentedness and information value. Data will be presented showing how both factors separately and combined affect word durations.
Lexical neighborhoods in speech production: A first report
Authors: Goldinger Stephen D. , Van Summers W.
Published: October 2005

Investigations of speech production have shown that talkers will systematically alter the acoustic-phonetic properties of their utterances in response to changes in the context in which the words are spoken. Well-known examples of such contexts are the presence of a loud background noise [e.g., Lombard (1911)], or the linguistic context surrounding the target word in a sentence [e.g., Lieberman, Lang. Speech 6, 172–188 (1963)]. Recent work by Balota and Shields [Psychonomic Soc. Conf. (1988)] suggests that factors intrinsic to words, such as their frequencies, may also affect the durations of spoken words. The present paper reports the results of a preliminary investigation of the effects of similarity neighborhood structure on speech production. Global, as well as segmental, comparisons of subjects' productions of words from dense and sparse lexical neighborhoods will be presented. [Research supported by NIH research grant NS-12179-11.]
The accentual pattern and prosody of the Chonnam dialect of Korean
Authors: Jun Sun-Ah
Published: October 2005

This paper examines the pitch accent and intonation patterns of the Chonnam dialect of Korean, spoken in the South Cholla province. The F0 contours show that the Chonnam dialect has two kinds of accentual patterns, low-high-low and high-high-low, the choice of which is determined by the first segment of a phrase. If the segment has a laryngeal feature of either [+ spread] or [+ constricted], a phrase beginning with the segment gets a h-h-l pattern. Otherwise, it gets a l-h-l pattern. Cross linguistically, it is well known that aspirated or glottalized segments cause higher F0 at the onset of the following vowel. However, these phonetic facts do not mean that the h-h-l pattern is a low-level product of the physiological effect. Rather, the occurrence of this accent pattern defines a phonological phrase. The F0 contours also suggest that the Chonnam dialect has two more units of prosodic structure above the phonological phrase within an utterance, namely the intermediate phrase and the intonational phrase. An intermediate phrase in Chonnam is characterized as the domain of downstep between phonological phrases. An intonational phrase is characterized by a high or high-low boundary tone. The data used in this paper are from the dialect spoken in Kwangju, the main city in the Chonnam province.
Intonational domains of the Seoul dialect of Korean
Authors: Lee Sookhyang
Published: October 2005

Pitch tracks were analyzed to determine the prosodic domains needed to described intonation patterns in the Seoul dialect of Korean. Three different domains are observed: the intonation phrase, the accentual phrase, and the phonological word. The intonation phrase consists of one or more accentual phrases, and is cued by the occurrence of a final falling or rising boundary tone configuration. The accentual phrase consists of one or more phonological words and is cued by an F0 peak at the beginning and a low-high accent on the last syllable. Since the initial peak is not associated with every word-initial syllable, it belongs to the accentual phrase and is not a correlate of word-initial lexical stress. Undershoot of the initial peak occurs when the accentual phrase is very short. There is also downstep between each accentual phrase within the intonational phrase; the pitch range is reset at the beginning of a new intonation phrase.
The role of phonological permissibility in the phonetic coding of speech
Authors: Wannemacher Carol A. , Sawusch James R.
Published: October 2005

Previous research has shown that phonological permissibility of a consonant sequence can affect the identification of an ambiguous phoneme [Massaro and Cohen (1983)]. The present experiment used both reaction time and identification measures to further explore this finding. With natural speech, little or no effect of phonological permissibility of a fricative-liquid sequence was found upon speed to classify the liquid. In the second experiment, a synthetic liquid series was constructed with endpoints varying in permissibility (depending on the fricative precursor). A speeded classification task was run and data were partitioned according to speed of response (cf. Fox, 1984). The results of this experiment, combined with the earlier findings, illustrate the relative roles of both acoustic-phonetic and phonological information in phonetic coding. The data will be discussed in terms of the data- and knowledge-driven influences upon phonetic coding. [Work supported by NINCDS.]
Attention to phonetic context across word boundaries
Authors: DeGroot Jenny , Nusbaum Howard C.
Published: October 2005

Variability in phonetic context affects phoneme perception. For example, subjects are slower to identify a target consonant when an adjacent context phoneme varies independently, compared to when context phonemes are constant across trials [C. C. Wood and R. S. Day, Percept. Psychophys. 17, 346–350 (1975)]. Further, this is true whether of not a syllable boundary intervenes between the target and the varying context, suggesting that subjects attend to phonetic context regardless of syllable structure [J. DeGroot and H. C. Nusbaum, J. Acoust. Soc. Am. Suppl. 1 85, S123 (1989)]. Do listeners similarly attend to phonetic context across a word boundary when recognizing a phoneme? In the present experiments, subjects identified a target phoneme, while an adjacent context phoneme either varied orthogonally or was held constant. In one stimulus set, the varying context occurred in the same word as the target; in the other stimulus set, the vrying context occurred in an adjacent word. Response times were measured to investigate whether the varying context slows target recognition across a word boundary as it does within a word. The results provide information about how listeners distribute their attention across the speech signal, and about the perceptual function of different linguistic units. [Research supported by NIH.]
The effects of attention on the phonetic integration of acoustic information
Authors: Eberhardt Jennifer L. , Gordon Peter C.
Published: October 2005

The present study investigated the effects of attention on phonetic processing. Thirty-five synthetic steady-state vowels varying from /i/ to /I/ were used. The first three formants of each vowel varied in seven equal logarithmic steps from /i/ to /I/ as the duration varied from short to long in five steps (50, 80, 120, 190, and 300 ms). All of the vowel stimuli were presented to subjects under high- and low-attention conditions. Attention was manipulated by requiring that subjects perform a nonspeech distractor task while simultaneously performing a speech identification task, or by requiring that subjects perform a speech identification task only. Phonetic identification of the vowel stimuli was found to vary with the attention condition. When subjects performed the distractor task and the speech task simultaneously, duration became a more important cue to phonetic identity, whereas the effect of formant frequency was reduced. A quantitative model was developed to characterize how the integration of information from the two kinds of cues, formant structure and duration, changed with attention level.
The intelligibility of LPC-vocoded words and sentences presented to native and non-native speakers of English
Authors: Mack Molly
Published: October 2005

The present study is an extension of previous work [M. Mack, J. Neurologist. 3, 293–316 (1988);M. Mack., J. Acoust. Soc. Am. Suppl. 181, S4 (1987)] designed to assess the intelligibility of natural and computer-generated speech presented to native and non-native speakers of English. In this study, subjects were presented with three tests—the Diagnostic Rhyme Test (DRT), a meaningful sentences test, and a semantically anomalous sentences test. Stimuli were presented in two conditions—natural and LPC (2.4 kbps) vocoded. Subjects were 20 native speakers of English and 20 native speakers of German, fluent in English. Results revealed that the non-natives performed significantly worse than the natives on all but the natural-speech DRT; word frequency affected accuracy more for the non-natives appeared to exhibit fatigue effects, unlike the natives, who exhibited perceptual learning. Moreover, the effects of test type and condition upon non-native response accuracy were nonadditive. Implications for models of non-native speech processing and the use of coded speech systems by non-native listeners are considered.
Perceptual categorization of synthesized /R-W/ continua in normal preschool children
Authors: Fitzgerald Laurie , Slawinski Elzbieta B.
Published: October 2005

The purpose of the present study was to examine the development of categorical perception of phoneme boundaries. A seven-step adult /R-W/ continua was synthesized via the Klatt cascade/parallel software program. The acoustic tokens varied according to the second (F2)- and third (F3)-formant onset frequencies and second (F2)- and third (F3)-formant transition rates. Percentage of correct responses on an identification task was computed to yield a measure of phonemic boundary location for adults and children of 3, 4, and 5 years of age. The phonemic boundaries fell between stimuli 3 and 4, at stimulus 4 and 5 for 3-, 4-, and 5-year-old children and adults, respectively. The finding that there was a shifting and increasing steepness in the phonemic boundaries as a function of age is supportive of previous research and moreover, of the theory that a child's phonological system is not inherently different than that of an adult but rather is just a simpler or less precise version of the mature system.
The role of auditory object formation in sentence perception
Authors: Carrell Thomas D.
Published: October 2005

Previous work has demonstrated that amplitude-modulated time-varying sinusoidal (AM-TVS) replicas of natural sentences were more intelligible than simple time-varying sinusoidal (TVS) sentences [T. D. Carrell, J. Acoust. Soc. Am. Suppl. 1 84, S158 (1988)]. The goal of the experiments reported here was to determine the cause of this increased intelligibility. One potential explanation was based on the fact that AMTVS sentences were rated more natural (i.e., more humanlike) than TVS sentences. This increased naturalness might have increased the probability that speech-specific analysis was brought to bear in decoding the incoming message. The second potential explanation was based on the idea that the comodulation of the three component tones of a TVS sentence might cause them to be grouped together as an auditory object for further processing. It has been suggested that “…amplitude modulation helps form auditory objects from complex sound fields” [W. A. Yost and S. Sheft, J. Acoust. Soc. Am. 85, 848–857 (1989)]. Evidence will be presented in favor of the second explanation. Specifically, the increase in intelligibility will be shown to be related to the comodulation of the three component tones and possibly to the mechanism underlying comodulation masking release (CMR). These findings suggest that the comodulation of the three tones comprising a TVS sentence create an auditory object and that auditory object formation is important in fluent speech understanding.
Acoustic scattering by laboratory scale modeled sea ice
Authors: Diachok Orest I. , Kille Robert M.
Published: October 2005

Laboratory scale-modeled experiments were designed to provide highly controlled data for evaluation of existing and guidance for new theories of acoustic scattering from Arctic sea ice. Results from previously reported measurements of scattering loss from parallel and randomly oriented sea ice ridges situated on a plate between air and water (McClanahan and Diachok) will be reviewed and new results of scattering (particularly backscattering) versus angle at both high and low frequencies will be presented. Implications for acoustic remote sensing of geometrical properties of sea ice at great ranges in the Arctic will be discussed.
Low-frequency scatter from a thin rough elastic plate: Theory and experiment
Authors: Tolstoy Ivan
Published: October 2005

The generalized smoothed boundary condition theory, based upon an original idea of Biot's [M. A. Biot, J. Acoust. Soc. Am. 44, 1616–1622 (1968)], and developed after 1979 by Tolstoy, offers a flexible and straightforward technique for obtaining simple, formal solutions for low-frequency sound scatter from distributions of scatterers of arbitrary shapes and properties of any type at liquid/liquid or liquid/solid interface. In special cases such as a perfectly hard wall with perfectly hard bosses or cylindrical corrugations, the boundary condition enables one to recover well-known solutions. After a brief review of prior successful applications to the interpretation of rough boundary model experiments, it is shown how the method can be applied to the reflectivity and phase problems for a plane wave incident upon a thin rough plate satisfying the Germain equation on the surface of a liquid. The predictions of the theory are found to agree well with recently reported model work [T. P. McClanahan and O. I. Diachok, J. Acoust. Soc. Am. Suppl. 1 84, S218 (1988)]. [Work supported by NRL and ONR.]
Measurements of under ice broadband coherence
Authors: Meredith Roger W.
Published: October 2005

The Arctic is a unique region acoustically, dominated by the under ice canopy. The ice varies seasonally in coverage, thickness, and roughness causing varying degrees of acoustic spatial and temporal variability. Horizontal coherence from explosive acoustic sources at a depth of 300 m under a relatively smooth Arctic ice pack is examined in the frequency range 100–1500 Hz over source-receiver ranges from 3–50 km. Coherence estimation is a difficult problem and is not defined theoretically for transient broadband signals. Mean-square-coherence is computed using frequency band averaging and is computed separately for the direct and ice-reflected propagation paths. Coherence is found to fluctuate significantly with source-receiver range, and acoustic frequency for both acoustic propagation paths. The highest values of coherence do not always occur at the lowest frequency bands. Inside the acoustic half-channel, above 300 m, coherence is less for the ice-reflected arrival. Changes in coherence due to under ice reflection are smallest for the 100- to 200-Hz octave band, indicating less coherence loss due to under ice scattering, but the change is sometimes as high as 50%. [Work supported by the Office of Naval Technology.]
Results of matched-field processing of low-frequency Arctic under-ice data
Authors: Livingston E. , Diachok O.
Published: October 2005

Matched-field processing of low-frequency (11 to 23 Hz) high signal-to-noise ratio cw signals in an Arctic (under-ice) environment has produced high signal gain (within 1 dB of theoretical) with good range and depth localization for frequencies of 17 and 23 Hz, at a range of 260 km on a 1-km-long vertical array. Range and depth errors were less than 1% and 1 wavelength, respectively [E. Livingston and O. Diachok, J. Acoust. Soc. Am. 86 (1989)]. At the lowest frequency, 11 Hz, the range estimates and gain were within 1% and 1 dB, respectively, but the error in the depth estimate was large, greater than three wavelengths. Replica fields were computed based on a measured but range-independent sound-speed profile and a constant bottom depth, whereas there was a major bathymetric feature along the propagation path. Possible causes for error in depth localization due to environmental mismatch in the computed replica fields at 11 Hz will be discussed.