bluuebunny/crossref_metadata_2025 huggingface dataset:
Acoustic wave scattering from infinite cylindrical clad rods
Authors: Honarvar Farhang , Sinclair Anthony N.
Published: October 2005

This paper considers the scattering of an infinite plane acoustic wave obliquely incident on an infinite clad rod. Comparing the form functions of the scattered pressure for the clad rod and a simple rod made of the cladding material, it is observed that the presence of the core will affect the lower mode resonances while the higher modes are not affected. The ratio a/b, where a and b are the radii of the core and the clad rod, respectively, is an indication of the boundary between the lower and higher modes. Additional resonances for this case are due to the surface waves propagating on the core/cladding interface. These resonances are highly dependent on the quality of the bond between the core and the cladding. Hence they could be used as key parameters in evaluation of the interfacial bond quality. A finite value of bond rigidity is used in order to model the core/cladding boundary. Using this approach the quality of the interfacial bond in the model can range for perfect bonding to complete debond depending on the values of the boundary stiffness constants.
Low-frequency volume scattering measurements from the central Mediterranean
Authors: Vaccaro Mark J.
Published: October 2005

Broadband (200–1500 Hz) measurements of direct path volume scattering were made in May of 1991 in the central Mediterranean’s Ionian Sea and adjacent Medina Bank. Acoustic sources used in these measurements were explosive charges detonated several hundred meters below a vertical line array (VLA) receiver. Reverberation was processed from the upward looking end-fire beam of the VLA yielding highly resolved scattering strengths in depth and frequency for the upper 400 m of the water column. Analysis of the spectral characteristics of the volume scatter data reveals that the dominant scattering emanates from diffuse, broadband strata which are confined to the thermocline region of the water column. The applicability of classic swimbladder scattering models to describe these layers is presented in addition to the spatial variability observed in volume scatter from deep (Ionian Sea) to shallow (Median Bank) ocean areas.
Extraction of target characteristics from the response of a ribbed cylindrical shell in a shallow water environment
Authors: Sarkissian Angie , Hughes David H. , Dragonette Louis R.
Published: October 2005

Bistatic and monostatic target strength values of a ribbed cylindrical shell contain various scattering phenomena such as Bloch waves, rib resonances, specular reflections and other effects due to waves traveling on the surface of the shell. When the target is placed in a shallow water environment, the response is further cluttered by the presence of the various multipaths that a signal travels in a bounded medium. By using a vertical line array of sources and receivers, the target response may be extracted. A vertical array of sources is used to suppress certain shallow water modes in the incident field. A receiver array is used to remove certain shallow water modes from the scattered field. Time-frequency analysis is a final filter for selecting the modes of interest for which the target response is extracted. The extracted target response is correlated against the free field target characteristics previously determined by time-frequency synthesis techniques.
Acoustic multipole logging in transversely isotropic two-phase medium
Authors: Zhang Bixing , Wang Kexie , Dong Qingde
Published: October 2005

An anisotropic reservoir is simulated by a transversely isotropic two-phase medium, and the acoustic field excited by a multipole source in a fluid-filled borehole is investigated. The medium outside the borehole is modeled following Biot’s and homogenization theories. Similar work has only be seen in Schmitt’s [J. Acoust. Soc. Am. 86, 2397–2421 (1989)] study, but he focused his attention on the behavior of the mode waves. In this article, not only are the dispersion and excitation of the mode waves analyzed thoroughly, but the propagation mechanism of the critical refracted P and S waves corresponding to the multipole source branch cut integrations is also investigated for the first time. The effect of the vertical and horizontal permeabilities, porosity, radius, stiffnesses, and other factors on the acoustic field is analyzed.
Connection between the dynamic bulk modulus of air in a porous medium and the specific surface
Authors: Lemarinier Pavel , Henry Michel , Allard Jean-F. , Bonardet Jean L. , Gedeon Antoine
Published: October 2005

A model for the prediction of the frequency dependence of the dynamic bulk modulus of air in a porous medium with one parameter, the thermal characteristic dimension Λ′, was proposed previously by one of the authors. This parameter depends only on the porosity and the area of the surface of porous frame in contact with the air in the material. This area can be evaluated with the standard Brunauer, Emmett, and Teller (BET) method, from krypton adsorption by the frame at liquid–nitrogen temperature. Comparisons between acoustically measured bulk moduli and predictions obtained with values of Λ′ evaluated with the BET method are presented. The BET results provide reasonable agreement with acoustic measurements of thermal dimensions and dynamic bulk moduli.
Propagation in fluids inside thick viscoelastic cylinders
Authors: Greenspon J. E. , Singer E. G.
Published: October 2005

This paper presents a study of wave propagation in a fluid contained inside a thick viscoelastic cylinder, which is used as a liner inside a rigid pipe to attenuate acoustic waves inside the fluid. Both the axially symmetric (axisymmetric) and nonaxially symmetric (asymmetric) waves are treated. A representative group of pipe sizes was chosen to illustrate the general behavior, and a viscoelastic material was chosen for which the viscoelastic constants have been measured. Velocity and attenuation plots are presented for pipes of various sizes with liners of different thicknesses.
Application of a κ-ε turbulence model to the prediction of noise for simple and coaxial free jets
Authors: Béchara W. , Lafon P. , Bailly C. , Candel S. M.
Published: October 2005

A numerical solution of a κ-ε turbulence model is used to provide local and statistical properties throughout simple and coaxial round jets. These are inserted into predictive formulas for jet noise based on Lighthill’s theory: Ribner’s formalism postulates locally isotropic turbulence superposed on mean flow; Goldstein and Rosenbaum’s formalism generalizes this to accommodate the more realistic assumption of axisymmetry. Numerical jet noise predictions via the Ribner/κ-ε model (designated Ra) and the Goldstein/κ-ε model (designated Ga), and some variants, are compared with experiment. Only a single empirical factor is used. The Ga model, with its threefold longer axial scale, shows closer agreement with experiment than the Ra model. The predictive capacity of the Ga model is demonstrated by further calculations for coaxial jets. The results confirm the experimental observation of a minimum of acoustic radiation when the outer flow has 0.4 the velocity of the inner flow. An advantage of the κ-ε method is that it yields information on the spatial and spectral distribution of the acoustic sources.
Deterministic reverberation from ocean ridges
Authors: Makris Nicholas C. , Avelino Lilimar Z. , Menis Richard
Published: October 2005

The deterministic relationship between low-frequency reverberation and detailed geomorphology is documented for wide-area insonifications of the western Mid-Atlantic Ridge. Charted reverberation registers precisely with extended ridges and has a high correlation with negative transmission loss, confirming previous analysis with lower resolution data [J. Acoust. Soc. Am. 95, 1865–1881 (1993)]. For a given ridge, prominent returns come from steep escarpments and cliffs that face the bistatic source and receiving arrays. This was hypothesized in the above reference, but could not be proven without the higher resolution waveforms and more sophisticated charting procedures of the present analysis. Monostatic and bistatic returns from the same lineated ridge at 1/2, 11/2, and 21/2 convergence-zone ranges are used to thoroughly document the registration with steep scarps. A decrease in resolution of the scattering site is also documented for increasing measurement range. Ambiguity from the horizontal receiving array is resolved by two independent methods that show close agreement for prominent returns. The first is an environmental symmetry breaking (ESB) technique that requires detailed knowledge of bathymetry to be incorporated into a range-dependent propagation model. The second is a global inversion of reverberation charts obtained from differing receiving-array locations and orientations. The global inversion requires no a priori environmental information and has not been previously applied to field data.
Arrival-time perturbations of broadband tomographic signals due to sound-speed disturbances. A wave-theoretic approach
Authors: Athanassoulis G. A. , Skarsoulis E. K.
Published: October 2005

The problem of arrival-time perturbations due to perturbations of the sound-speed profile is studied on the basis of full-wave equation modeling of the direct problem. Arrival times are analytically modeled as the time instants corresponding to the significant maxima (peaks) of the arrival pattern, in full agreement with measurement practice. In this framework the identification of actual (measured) arrivals as ray or modal ones is not required. An elegant perturbation formula is derived for the arrival times, containing the background arrival times, time derivatives of quantities associated with the background field, and also the functional derivative of the background field with respect to the sound-speed profile. This formula is of a system-theoretic nature and can be applied to any kind of environment, either range-dependent or range-independent. The restriction to the range-independent environment permits further elaboration of the perturbation formula since, in this case, the functional derivative of the acoustic-channel transfer function can be analytically expressed, e.g., in terms of normal modes. The performance of the proposed approach is demonstrated by studying two test cases: the linear- and the canonical-profile waveguide. The agreement between actual arrival times, obtained by numerically solving the direct propagation problem, and the arrival times predicted by means of the perturbation formula is very satisfactory. Since the proposed scheme can predict arrival-time perturbations even in cases that the arrival times cannot be identified as ray or modal ones, it is expected to be helpful in extending the applicability of ocean acoustic tomography.
Inversion for geometric and geoacoustic parameters in shallow water: Experimental results
Authors: Gingras Donald F. , Gerstoft Peter
Published: October 2005

Experimental results on the estimation of both geometric and geoacoustic parameters in shallow water are presented. Genetic algorithms are used for estimation of the forward model parameters; the estimated parameters are then used by a standard Bartlett processor for source localization. A stationary source at a range of 5.6 km and a moving source at ranges from 5.8–7.7 km were successfully localized in range and depth using a single frequency Bartlett processor. The results indicate that global estimation of the forward model parameters significantly improves source localization performance.
Coupled vibration in hollow cylinders of longitudinally polarized piezoelectric ceramics
Authors: Shuyu Lin
Published: October 2005

Longitudinally polarized piezoelectric ceramic disks with central holes have been the most commonly used elements in underwater acoustics and ultrasonics. However, their vibrational characteristics and frequency spectra have not been thoroughly studied. In this paper, when the mechanical coupling coefficient is introduced and the shearing strain is ignored, an analytic method is presented. The coupled vibration of the longitudinally polarized piezoelectric ceramic disks with central holes is studied and the resonance frequency equations are derived. Based on the frequency equations, the longitudinal and radial resonance frequencies can be obtained when the dimensions and the material parameters are given. Compared with one-dimensional theory, the computed resonance frequencies in this paper are in good agreement with the measured results. Compared with the numerical methods, the analytic method presented in this paper is simple in computing the longitudinal and radial resonance frequencies and in analyzing the coupled vibrational modes of the piezoelectric ceramic disks with central holes.
Timing effects of postvocalic voicing and distinctive vowel length
Authors: Behne Dawn M. , Moxness Bente , Czigler Peter E.
Published: October 2005

Syllable-internal timing can be affected by a variety of factors, including postvocalic voicing and distinctive vowel length. Both factors have been found to inversely affect vowel duration and the duration of a postvocalic consonant, resulting in similar rhyme-internal timing patterns. Is there any indication that syllable-internal timing uniquely characterizes distinctive vowel length and postvocalic voicing? Three experiments have been carried out investigating combinations of postvocalic voicing and distinctive vowel length in English, Norwegian, and Swedish. For each language a controlled set of CVCs was selected in which the final consonants were either voiced or voiceless. In addition, Norwegian and Swedish CVCs were selected which had distinctively short or long vowels, and for English, words were chosen which contained inherently short and long vowels. The target items were recorded in carrier sentences and durations of the initial consonant, the vowel, and final consonants were measured. Results demonstrated the expected inverse timing relations within the rhyme associated with postvocalic voicing and distinctive vowel length. In addition, prevocalic consonant duration was consistently distinct for conditions of postvocalic voicing compared to distinctive vowel length. Findings for English, Norwegian, and Swedish will be discussed in terms of syllable-internal timing.
Laxness of voice quality integrates with F1 (usually, but not always, negatively)
Authors: Walsh Laura , Bartels Christine , Kingston John , Macmillan Neil A.
Published: October 2005

Both lax voice and advanced tongue root typically concentrate energy at low frequencies: Laxing the voice increases the relative prominence of the first harmonic, and advancing the tongue root lowers F1. A previous study [Thorburn etal., 2871 (A) (1994)] using the Garner paradigm found that these acoustically similar effects integrated perceptually for vowels in CVC context. In this study, the range of voice quality was extended to include tensor values. Across the entire set of voice qualities sampled in the two experiments, laxness integrated negatively with F1 at the lax and tense ends of the continuum but positively at intermediate values. This pattern of meanintegrality is distinct from the additional finding of varianceintegrality, that is, greater uncertainty in judging voice quality when F1 varied than when it did not (and similarly for judgments of F1). According to a model of Durlach etal. [Percept. Psychophys. 46, 293–296 (1989)], the variance-integrality effects can be attributed to a sensory rather than a context-coding source. [Work supported by NSF and NIH.]
An articulatory and perceptual study of Tamil liquids
Authors: McDonough Joyce , Johnson Keith
Published: October 2005

In Tamil there are 5 liquid consonants. They are the lateral approximation [l], the retroflex lateral approximant [hooked el], the alveolar tap [inverted sm cap jay], the retroflex tap [hooked are], and an obscure segment that has been variously described. This paper presents electropalatography data from one speaker and perceptual data from five listeners exploring the articulatory and acoustic dimensions of the phonetic space for liquids in Tamil. The dimensions which are explored include duration (distinguishing flaps and approximants), dynamic tongue movement (distinguishing retroflex and nonretro- flex), and constriction location/spectral shape (distinguishing [l] and the obscure liquid). Preliminary analyses suggest that the obscure liquid of Tamil is an apicopalatal central approximant. However, unlike other segments in Tamil which require tongue tip backing (the retroflexes) there is no evidence of dynamic tongue movement during the closure and some suggestion of acoustic zeros, perhaps from a lateral opening. Additional perception data designed to clarify this picture will be presented.
Articulatory modeling of so-called advanced tongue root vowels
Authors: Fulop Sean , Kari Ethelbert , Ladefoged Peter
Published: October 2005

Many West African languages have two sets of vowels that are said to differ by one having an advanced tongue root [+ATR], and the other a retracted tongue root [−ATR]. The [+ATR] set may also have an enlarged pharynx and a lowered larynx. Words (roots) in these languages must contain vowels that are all of one set or the other. To test whether there is a constant articulatory difference between the two sets of vowels in Degema, a Delta Edoid language spoken in Nigeria, DAT recordings were made of 8 speakers. For 2 of the speakers, frontal and lateral videos were made of the lip aperture. The frequencies, amplitudes and bandwidths of the first 3 formants of the 5 pairs of vowels were determined from LPC analysis. These data were modeled using an articulatory synthesizer. After an appropriate set of vocal tract shapes had been determined for the [−ATR] set of 5 vowels, articulatory perturbations such as tongue root advancement, pharynx enlargement, and larynx lowering, were applied to the modeled [−ATR] vocal tract shapes to generate the [+ATR] set. A variety of articulatory gestures seem to be needed to convert vowels from one set into the other.
The relation between dialect attribution and vowel judgments
Authors: Faber Alice , Brancazio Lawrence , Best Catherine T.
Published: October 2005

A spoken word’s phonetic form provides information not only about the speaker’s intended message but also about the speaker’s language and/or dialect background. The form [dak] may reflect southern U.S. dike, Boston dark, or Chicago dock. Someone who makes an incorrect dialect attribution may misinterpret statements about the [dak]. Anecdotal reports of such misunderstandings abound (e.g., Labov, 1994). In an experimental investigation, it was assessed whether listeners’ labeling of isolated words is systematically influenced by correct versus incorrect attribution of speaker dialect. Words that are incorrectly assigned to their own dialect should be mislabeled, in ways predictable from the relative positions of vowel nuclei in the vowel spaces of the two dialects. Stimuli were tokens of heed, hayed, head, hood, hoed, HUD, produced by Utah and Connecticut women. Discriminant analyses trained on the Connecticut productions correctly classified Utah heed, hayed, and head; Utah hoed was often classified as Connecticut hood, and Utah hood and HUD were classified as Connecticut head. Connection listeners answered two questions about each token: i. What word is the speaker saying? and, ii. Does she speak the same dialect you do? Their judgments were generally consistent with the discriminant analysis classifications.
Perceptual assimilation of North German vowels to American English categories
Authors: Trent Sonja A. , Fitzgerald Brett H. , Crouse Susan M. , Strange Winifred
Published: October 2005

Perceptual assimilation of NG vowels to AE categories was assessed with stimuli in which the vowels occurred in /hVp/ syllables spoken in citation form and in the sentence, ‘‘Ich habe /hVp/ gesacht.’’ Subjects were presented multiple tokens of 14 NG vowels produced by 4 male talkers. They selected the AE vowel category to which the NG vowel was most similar and rated its goodness-of-fit on a 7-point scale from ‘‘English’’ (7) to ‘‘foreign-sounding’’ (1). ‘‘Identical’’ vowels (transcribed as the same across languages) did not necessarily assimilate to the predicted category. ‘‘New’’ front rounded vowels /y, Y, o/,œ/ assimilated to back rounded AE vowels. Perceptual goodness-of-fit was not always predicted from the phonetic description or acoustic similarity in F1/F2 space [B. H. Fitzgerald etal., J. Acoust. Soc. Am., this session]. Differences in modal identification response and goodness-of-fit were noted across citation versus sentence context and across individual speakers. Assimilation on the basis of intrinsic duration information was more consistent for syllables presented in sentences. These results have implications for studies of cross-language similarity which use citation-form stimuli. [Work supported by NIDCD.]
Acoustic specification of North German vowels produced in citation and sentence contexts
Authors: Fitzgerald Brett H. , Trent Sonja A. , Stack Janet W. , Ling Xiange , Strange Winifred
Published: October 2005

As part of a larger study of the effects of speech style and consonantal context on the acoustic specification and cross-language perceptual similarity of vowels, this study examined differences in acoustic parameters of North German (NG) vowels in hVp syllables produced in citation-form (as lists) and in the carrier sentence ‘‘Ich habe—gesacht.’’ Two instances of each of 14 vowels produced by 4 male speakers (Kiel dialect) spoken in each context were analyzed. Vowel formant frequencies (measured at syllable midpoint) showed some undershoot of F1 in sentence context relative to citation context; F2 undershoot was minimal. Duration differences between spectrally similar tense-lax pairs varied as a function of vowel height in both citation and sentence contexts. Overall, tense-lax duration differences were reduced in sentence context relative to citation form. Individual differences across speakers in both F1/F2 targets and intrinsic durations were noted. Distances in F1/F2 space could not account for perceptual assimilation patterns of AE listeners [see S. Trent etal., J. Acoust. Soc. Am., this session]. These results have implications for conceptions of phonetic prototypes used to account for cross-language similarity. [Research supported by NIDCD.]
Acoustic correlates of Deg Xinag/Ingalik Athabaskan vowels
Authors: Taff Alice
Published: October 2005

There has been controversy [A. Jerue etal., Deg Xinag Dindlidik. ANLC: Fairbanks (1993)] over the classification of the vowel in the second person plural morpheme (2p) in Deg Xinag/Ingalik as either /o/ or /inverted closed omega/. Acoustic measurements were undertaken towards resolving the issue. F1, F2, F3, and duration were measured for each of the five vowels in the system, /a,e,o,inverted closed omega,schwa/. Contexts were limited to coronal and uvular. F1 and F2 means for data from two speakers indicate that 2p is more like /inverted closed omega/ than /o/. Vowel length data supports this claim.
About the fourth angle of the ‘‘vowel triangle.’’
Authors: Carré René
Published: October 2005

The vowel triangle can be derived from the acoustic theory [R. Carré etal., 2924 (A) (1994)]. The area function was deformed in order to increase or decrease F1 or F2. In this new study, the acoustic criterion is to increase (or decrease) both F1 and F2 or to increase F1 (or F2) and decrease F2 (or F1). At the end of the deformation process, the area functions produce the most ‘‘compact’’ (F1 and F2 close as in /a/) or ‘‘diffuse’’ (F1 far from F2 as in /i/) or ‘‘grave’’ (F1 and F2 both low as in /u/) sounds. But what about an ‘‘acute’’ vowel (F1 and F2 both high) which could correspond to the fourth angle? It can be automatically converged to a pattern where F1 is around at 1000 Hz and F2 at 2000 Hz. But in this case the ratio between the maximum value of the cross-sectional area divided by the minimum value becomes around 80. This ratio is only 20 (between 0.5 and 10 cm2) for the ‘‘compact’’ versus ‘‘diffuse’’ axis (from /a/ to /i/). Thus reaching this fourth angle is too much costly in deformation amplitude and thus poorly efficient.
Production of highly similar vowels by language-impaired children
Authors: Stealy June , Stark Rachel E. , Heinz John M.
Published: October 2005

It has been shown that language impaired (LI) children have greater difficulty than language normal (LN) children in identifying the synthesized vowels /ε/ vs /œ/, but not /open aye/ vs /i/, when the members of test pairs are of equal duration (240 to 40 ms) [R. E. Stark and J. M. Heinz, 2360 (A) (1992)]. It was concluded that, when deprived of the durational cues present in natural speech, LI children were less well able than LN to rely upon subtle spectral cues. In the present study, children in both groups (11 LI, 9 LN) were asked to imitate the synthesized vowels /ε/ and /œ/. Their responses were recorded, transcribed, and submitted to spectral analysis. Responses of individual children that were given to either /ε/ or /œ/ were scored as correct, those that were given to both vowels indiscriminately were not. The scores of the two groups were not significantly different. However, the LI children’s responses were transcribed as more variable, and occupied a greater range within F1−F2 plots, than those of the LN children. The results support the hypothesis that LI children have ‘‘fuzzy’’ phonological categories. [Work supported by NIH.]
Coupling between flexural and membrane wave types due to multi-degrees of freedom and rotational fuzzy attachments
Authors: Russell Daniel A. , Sparrow Victor W.
Published: October 2005

In current fuzzy structure theory, the fuzzy substructure is generally modeled as a system of independent 1-DOF oscillators attached to the master structure. Several assumptions are usually made. Firstly, while the attachments are applied to one side only of the master structure (plate or shell), the effects of asymmetric loading are ignored. In this paper, it is shown that the asymmetric loading may provide a coupling mechanism between flexural waves and membrane waves in plates and shells, thus altering the predicted added damping effect of the fuzzy substructure. Secondly, until now the motion of the attachments is usually restricted to only one translational direction. This paper considers the possibility of coupling between wave types in plates and shells when the fuzzy attachments are allowed to move in three translational directions, as well as rotational motion about their attachment points. Furthermore, the effects of these new attachment motions are analyzed using a wave impedance/dispersion relation approach. [Work supported by ONR.]
Interactions between acoustic dimensions contributing to the perception of voicing
Authors: Hall Michael D. , Davis Katharine , Kuhl Patricia K.
Published: October 2005

It is well known that several dimensions contribute to the classification of stop consonants as voiced or voiceless. Three Garner speeded classification experiments evaluated the nature of perceptual interactions between such dimensions. Specifically, the experiments examined the potential integrality between pairs of three critical dimensions—voice onset time (VOT), aspiration amplitude, and fundamental frequency (F0) at the onset of voicing. Only within-category (/ka/) syllable stimuli were used to eliminate phonetic classification as a basis for subjects’ responses. Evidence was found for the asymmetric separability of VOT and F0; while variability along F0 significantly influenced VOT classification speed, variability along VOT did not similarly influence F0 classification. A similar pattern of asymmetric separability for F0 and aspiration amplitude was demonstrated, where aspiration variability did not interfere with F0 classification. In contrast, VOT and aspiration amplitude were completely integral, with variability along either dimension influencing classification speed along the other dimension. Furthermore, performance accuracy reflected a time-intensity trade-off between perception of VOT and aspiration. The results indicate that F0 and VOT/aspiration amplitude may contribute to two distinct sets of perceptual analyzers. Implications for phoneme perception will be discussed. [Work supported by NIH.]
Transient grating studies of nonlinear photoacoustic effects in particulate solutions
Authors: Diebol G. J. , Chen H. X. , Cao Y. N. , Zimmt M. B.
Published: October 2005

Experiments where transient grating signals are recorded from irradiation or particulate matter are reported. A relatively low power, picosecond laser produces transient grating signals in reverse micellar solutions that have a unique time dependence, and which can be explained by heat diffusion from the interior of the micelle to a surrounding organic solvent. A 16-ns-long, high-power pulse from a Q-switched ND:YAG laser irradiating a gold sol produces a diffracted light signal that is explainable in terms of a thermally generated photoacoustic effect. Particulate carbon, on the other hand, gives transient grating signals that appear to possess an overtone of the usual thermally generated fundamental frequency. The effect is nonlinear in its dependence on the laser intensity, and is dependent on the time of irradiation of the solution. A second characteristic of the effect is that a pronounced noise is generated by the solution on firing the laser. It is believed that the effects can be attributed to endothermic chemical reactions at the surface of the carbon that act to unbalance the thermal and acoustic modes producing an acoustic density that oscillates about the ambient. Since the diffracted light signal is proportional to the square of the acoustic density, what appears to the eye as an overtone is seen in the recorded signal.
Forward and backward projection of transient acoustic field functions obtained from schlieren and fiber-optic measurements
Authors: Sun Jie , Stepanishen Peter R. , Clement Gregory , Liu Ruiming , Letcher Stephen V.
Published: October 2005

A combination of a schlieren system and a polarimetric fiber-optic detection system is used to obtain line integrals of transient acoustic fields a distance z in front of a planar source. The x,y dependence is obtained from a tomographic reconstruction algorithm. The signal is then forward projected away from the source or back-projected toward the source using wave vector/time domain and frequency methods. Numerical results will be presented to illustrate the projection methods for a number of different transient signals from planar sources with separable and nonseparable space/time velocity distributions. Experimental results for selected source distributions from pulsed ultrasonic transducers will then be presented and discussed.
Numerical study of a simplified model of nonlinear processes in thermoacoustic engines
Authors: Prosperetti A. , Watanabe M.
Published: October 2005

A simplified one-dimensional model of thermoacoustic devices, obtained by integrating the governing equations over the tube cross section, was described earlier. Here the results of a numerical exploration of the model as applied to a prime mover are described. The effects of temperature distribution, wall drag, heat transfer, and cross-sectional area variations are explored and compared with available experimental results. Some initial results for the heat pump configuration will also be presented. [Work supported by the Office of Naval Research.]
The effect of phase of the acoustic wave on the efficiency of thermoacoustic refrigerators
Authors: Brewster James , Raspet Richard
Published: October 2005

An analytic approach to the study of thermoacoustics and application of this technique to the optimization of a refrigerator driven by an arbitrary acoustic wave will be presented. It will be shown that although a standing wave driven cooler has close to optimum efficiency, the efficiency can be improved by the addition of a traveling component to the wave field flowing in the direction of negative temperature gradient. The value of the acoustic impedance in the gas bordering the cold end of the stack is fixed to an arbitrary value. Application of the continuity of pressure and velocity is combined with the wave equation to yield the value of the pressure wave function and its first two derivatives at the cold end of the stack. Knowledge of these allows the direct calculation of the efficiency of refrigeration and the second derivative of the temperature distribution. [Work supported in part by Office of Naval Research.]
The index of interaural envelope correlation: Normalized cross-covariance or normalized cross correlation?
Authors: Bernstein Leslie R. , Trahiotis Constantine
Published: October 2005

This study principally evaluated whether the normalized cross covariance (Pearson product-moment correlation) or the normalized cross correlation describes discriminability of changes in interaural disparities conveyed by the stimulus enveloped. In a four-interval, two alternative task, listeners detected which interval contained a 4-kHz tone added antiphasically to diotic, 200-Hz-wide, noise (NoSπ). The ‘‘nonsignal’’ intervals contained the tone added homophasically (NoSo). Discriminability (d’) was measured as a function of S/N for values between −30 and +30 dB (really!). For all S/N’s, overall level was 70 dB SPL. Listeners’ performance was very well accounted for by the normalized cross correlation but not the normalized cross covariance. Additionally, listeners were tested in a ‘‘direct’’ discrimination task where changes in envelope correlations (Δρ) were produced by ‘‘mixing’’ two independent Gaussian noises. Although Δρ’s at threshold (d’=1.0) obtained from the two tasks were similar, the psychometric functions obtained with the direct discrimination task were more steep. Discussion will include how the normalized cross correlation of the envelope accounts for classic data concerning discriminability of interaural time differences at high frequencies as a function of depth of modulation. [Work supported by NIH DC02103.]
Precedence and plausibility
Authors: Yost William A. , Guzman Sandra J.
Published: October 2005

The ‘‘Clifton effect’’ [R. K. Clifton, 1834–1835 (1987)] was studied in a sound-deadened room with seven loudspeakers. One loud speaker produced a source click while other loudspeakers produced delayed copies simulating echoes (delays: 2–30 ms). Each combination of source and echoes is one click event and was presented as a train of click events (1–20 click events). A train was presented to listeners who made two judgments for the LAST click event presented: (1) The number of loudspeakers which produced sounds for the last click event, and (2) the loudspeaker location for each perceived source. ‘‘Catch trials’’ were introduced to make sure listeners used all possible responses and were able to locate the loudspeaker sources. When more than 10 click events were presented, a switch in conditions was introduced between the 10th and 11th click event. If the switch was plausible for a natural source and its echoes, responses indicated that listeners processed delayed clicks as echoes. If the change was implausible, then responses after the switch changed indicating listeners processed all clicks as if they were sources rather than echoes. [Work supported by NIH and AFOSR.]
Cochlear acoustic reflectance and traveling wave delay
Authors: Kimberley Barry P. , Shaw Greg , Shera Christopher , Allen Jont B.
Published: October 2005

Inner ear acoustic impedance and reflectance, SFOAEs, DPEs, and PTTs were measured with a calibrated probe situated in the ear canal of normal-hearing subjects. The use of a calibrated probe allowed for the conversion of the SFOAE recordings into reflectance. In a number of subjects, low stimulus levels results in rippling of the reflectance. The phase slope of the acoustic reflectance was found to be a linear over a narrow range of frequencies. This slope is taken as equivalent to the traveling wave delay to the corresponding frequency(ies). Traveling wave delay estimates (reflectance phase slope) however did not change as stimulus level ranged from 50 to 10 dB SPL. This is in contrast to previous traveling wave delay estimates using DPEs where delay increased with a decrease in stimulus level [Kimberley etal., 1343–1350 (1993)]. The discrepancy between DPE-based and SFOAE-based estimates of traveling wave delay is discussed.
Orofacial and finger force control in normal subjects
Authors: Gentil Michèle , Rezali Abdelkader , Tournier Claire Lise , Pollak Pierre , Benabid Alim L.
Published: October 2005

The relationship among several parameters of the ramp-and-hold force contraction and target force level was quantified for the upper lip, lower lip, and tongue on the one hand, and right and left index on the other hand, in 12 normal subjects (6 males and 6 females). Using visual feedback, subjects produced ramp-and-hold compression lip, tongue, and index forces as rapidly and accurately as possible to end-point target levels ranging from 0.25 to 2 newtons, these fine force occurring within physiologic levels presumably involved in speech production. Given the special anatomic and physiologic characteristics of the orofacial system, the purpose of this study was to compare lip, tongue, and finger force control in order to determine whether the motor control is uniform in both systems, that of the speech production and that of the limb, and within subsystems of speech production. Consequently, can be pathophysiology of a movement disorder in its stereotypic form be considered across limb and speech systems? It seems likely that measures of orofacial force control provide useful insights into the fundamental motor control problem of any individual with dysarthria.
Shallow water propagation in the presence of a rough sea surface and the associated bubble clouds
Authors: Norton Guy V. , Novarini Jorge C. , Keiffer Richard S.
Published: October 2005

Propagation models in underwater acoustics usually incorporate the sea-surface roughness as a perturbation, (i.e., a loss mechanism through an additional attenuation factor) based on coherent loss in the specular direction. In addition, scattering kernels are generally derived assuming a homogenous medium underlying the sea surface, an assumption incompatible with a realistic environment. Using a numerical model [Norton etal., 3018(A) (1994)] that combines a high-fidelity parabolic equation propagation model with the conformal mapping technique to handle surface roughness in a marching algorithm developed by Dozier [L. B. Dozier, 1415–1432 (1984)], forward propagation under a rough surface can be modeled in a mathematically consistent way. The technique is applied to the problem of shallow water propagation in the presence of an inhomogeneous bubble distribution. The ocean environment consists of bubble plumes in different stages of development. The effect of the bubbles are introduced through the complex index of refraction. The model is exercised for frequencies between 20 and 40 kHz. The combined effect that the rough surface and the inhomogeneous environment has on amplitude and phase fluctuations and on transmission loss is examined. [Work supported by ONR.]
Deriving scattering strengths from nonstationary time-series data: A comparison of low-frequency surface-backscattering strengths using both impulsive and coherent sources
Authors: Gauss Roger C. , Ogden Peter M. , Chester John B. , Fialkowsi Joseph M.
Published: October 2005

The derivation of scattering strengths from acoustic field data involves applying the active sonar equation to the measured reverberation response. However, due to the typical nonstationarity observed in the direct-path reverberation time series (e.g., 10 dB/s), the choice of appropriate corresponding grazing angles becomes more problematical as the duration of the transmitted signal increases. Direct-path measurements of low-frequency (200–1000 Hz) acoustic surface scattering were made in the Gulf of Alaska in the February of 1992 using interleaved SUS and pulsed waveforms (cw, FM). Backscattering strengths were derived for pulse lengths varying between 50 ms and 2.4 s. A comparison of results revealed that scattering strengths have a nontrivial dependence on signal type and pulse length, and on the signal-processing methodology used in their derivation. General implications for deriving scattering strengths from nonstationary time-series data will be discussed. [Work supported by ONR (NRL).]
Effect of surface height distributions on underwater acoustic backscattering statistics
Authors: Becker Kyle M.
Published: October 2005

A problem of interest to ocean environmental acousticians is understanding the relationship between ocean surface characteristics and acoustic backscattering statistics. Recent experimental work has focused on determining surface properties which cause backscattering strength statistics to deviate from exponential. Using the nomenclature of Ogilvy (TheoryofWaveScatteringfromRandomRoughSurfaces, 1991) several scattering surfaces have been fabricated. Surfaces were modeled using a moving average technique with prescribed distribution functions and correlation functions C(R). Representing surface elevation, h, as a continuous random process, the moving average process of order N is given as hn=∑Nl=0wlun−1. Statistical properties of h are determined by the random uncorrelated variables, un, and the choice of weights, wl. Weights are determined by the choice of C(R) and corresponding correlation length, λ0, or distance over which C(R) decays by 1/e. Isotropic and anisotropic surfaces have been constructed for both Gaussian and non-Gaussian surface height distributions. Acoustic backscattering results are presented for three cases: case I—log-normal height distribution in x and y, equal correlation lengths; case II—Gaussian height distribution, correlation length in y equal to ten times that of x; case III—Gaussian height distribution in x, log-normal distribution in y, equal correlation lengths.
Ultrasonic studies of phase transitions in lipid membranes and protein molecules
Authors: Kharakoz Dmitri P.
Published: October 2005

This paper reviews phase transitions in the lipid membranes and protein molecules studied by means of ultrasonic (sound velocity and absorption) and related methods (calorimetric, volumetric, and others). Peculiarities of phase transitions in small-dimension systems in an aqueous environment (a finite width of the transition zone, probability of critical nuclei formation, hysteresis, hydration changes, etc.) are discussed. A comparison of ultrasonic and calorimetric methods showing their complementarity in the studies of kinetics of phase transitions is presented. Ultrasonic data on the melting of lipid vesicles in aqueous dispersions are reviewed. Recent achievements in the ultrasonic study of the kinetic mechanism of creation and growth of gel nuclei within the parent liquid-crystalline phase are reported. Ultrasonic studies of the protein/lipid interactions are reviewed and perspectives are outlined. Native to molten globule state transition in globular proteins is considered (volume and compressibility changes, acoustic relaxation, protein interior hydration). The differences in the behavior of the phase transitions in membranes and in protein molecules are discussed. New questions for further ultrasonic studies of the phase transitions are formulated.
Molecular acoustics in thermodynamic characterization of proteins
Authors: Chalikian Tigran V.
Published: October 2005

Processes such as conformational phase transitions, ligand binding events, and enzymatic catalysis alter the structure of proteins as well as the nature of their solvent accessible surface. Consequently, these processes result in corresponding changes in the sound velocity of the protein solution. As is shown by the example of two typical globular proteins, cytochrome c and α-chymotrypsinogen A, the transition from the native state to the molten globule state is accompanied by an increase in sound velocity, while the native state–unfolded state transition is accompanied by a decrease in sound velocity. The interpretation of the macroscopic sound velocity data for the different phase states of proteins in terms of microscopic structural and hydrational differences is a very sophisticated problem. One of the ways of attempting to solve the problem of distinguishing between the contributions of protein structure and hydration to the sound velocity is to search for correlations between the structural crystallographic data of a large number of globular proteins and their ultrasonic velocimetric characteristics.
Intestinal hemorrhage produced by pulsed ultrasound or lithotripter fields
Authors: Dalecki Diane , Child Sally Z. , Raeman Carol H. , Carstensen Edwin L.
Published: October 2005

The threshold for intestinal hemorrhage in mice was determined using a piezoelectric lithotripter. Mice were exposed to 200 lithotripter pulses with a PRF of ∼1 Hz. The amplitude of exposure was determined by either varying the position of the animal relative to the focus or by varying the voltage used to charge the lithotripter. Threshold for intestinal hemorrhage occurred at a peak acoustic pressure of 1–2 MPa. At threshold, the lithotripter waveform was nearly sinusoidal. Thresholds for intestinal hemorrhage were also determined for exposure to pulsed ultrasound at frequencies of 0.7, 1.1, 2.4, and 3.6 MHz. Intestines were exposed at 3–4 sites for 5 min per site using focused sources operating with a 10-μs pulse length and 100 Hz PRF. The threshold at 1.1 MHz was ∼1.5 MPa and thresholds increased with increasing frequency. Temperature rises of 1 –2 °C were measured in the intestine during exposure at the highest exposure conditions. Both the frequency dependence of intestinal hemorrhage and the limited heating are consistent with a cavitation mechanism of action.
Community noise: The mainstream approach
Authors: Plotkin Kenneth J.
Published: October 2005

Community noise analysis and control has been a concern for centuries. The introduction of jet commercial aircraft in the 1950s escalated it to a widespread practice with widely accepted quantitative rules. The rules have their technical basis in scientific studies ranging from laboratory psychoacoustic experiments through social attitudinal surveys. Implementation is in the form of land use planning and noise control regulations. A review is presented of the current practice, its successes, and its limitations.
A new analytical approach for radiation problem from finite cylindrical piezoceramic shell
Authors: Grinchenko Victor T.
Published: October 2005

The objective of this paper is to present a complete analytical solution for a finite piezoelectric cylinder radiation problem. Three aspects of the problem are discussed. (1) Development of a theory of thin piezoceramic shells with hypotheses for electric field components that are equivalent to the classical Love’s mechanical ones. (2) Explanation of a new analytical approach to solve a coupled elastic–electric–fluid interaction problem. The exact solution for the acoustic potential function is given in terms of an infinite series of partial solutions of the Helmholtz equation in cylindrical and spherical coordinate systems. The associated coefficients are the solution of an infinite linear system. A new approach to truncation of this system which takes into account the sharp edge effects, is developed. An estimation of the calculation accuracy of the method is presented. (3) Numerical implementation of the analytical solution for different values of key parameters gives a ground to elucidate a complex exchange of energy between electric generator, elastic structure, and surrounding fluid. Modification of eigenforms of the shell due to radiation in water is described.