bluuebunny/crossref_metadata_2025 huggingface dataset:
Multi-frequency scintillation method for ocean flow measurement
Authors: Fuks Joseph , Naugolnykh Konstantin
Published: July 2002

A multi-frequency scintillation method for ocean flow measurement is presented. The transverse flow of inhomogeneous fluid produces fluctuation of the acoustic signal passing through it. These fluctuations vary with the cw signal frequency change due to variation of the Fresnel zone size and diffraction angles. Respectively, the fluctuations of signals at two different frequencies are coherent at low frequency and noncoherent in the high-frequency band. The frequency cutoff of the correlation function of signals fluctuation depends upon the flow velocity at given fine structure of the flow. The measurement of the cutoff frequency allows one therefore to determine the flow velocity of the fluid [J. Fuks, Radiotekhn. Elektron. (in Russian), 3, 515–524 (1975)]. This method can be considered as the ‘‘frequency-domain’’ version of the conventional scintillation approach to the current velocity registration based on measurement of correlation of the signals transmitted from the source to two separated in space receivers and can be, respectively, considered as space-domain scintillation method [S. Clifford and D. Farmer, J. Acoust. Soc. Am. 74, 1826–1832 (1983)]. The features of the multi-frequency method of the ocean current measurement including the optimal frequency dependence upon the distance and the ocean environment are considered in the paper.
The stress dependence of the piezoelectric d coefficient of piezoelectric and electrostrictive ceramic materials
Authors: Yang Guomao , Mukherjee Binu K.
Published: July 2002

An experiment has been developed to measure the piezoelectric d coefficient as a function of uniaxial stress on a piezoelectric or electrostrictive ceramic material. Measurements on piezoelectric ceramic specimens show that there is a very significant enhancement in the value of the piezoelectric coefficient as a function of applied stress with the value of the coefficient going up by a factor of about 2.5 over a 100-MPa range of applied stress. The increase in the piezoelectric coefficient continues until the stress is large enough for the ceramic to start depoling. Electrostrictive ceramics also show a similar trend, although their lack of mechanical strength prevents measurements over a large range of stress. Our results suggest that the performance of transducers can be enhanced by ensuring that the active piezoelectric material is under stress. [Funding support from the U.S. Office of Naval Research is gratefully acknowledged.]
Conditions for ocean acoustic matched field inversions to be unbiased and attain the Cramer–Rao bound
Authors: Makris Nicholas C. , Naftali Eran
Published: July 2002

In recent years, a wide variety of acoustic techniques have been developed to probe the marine environment. These techniques typically require the nonlinear inversion of acoustic field data measured on a hydrophone array. The data, however, are often randomized by the addition of naturally occurring ambient noise or by fluctuations in the waveguide’s refractive index and boundaries. The nonlinear inversion of random data often leads to estimates with biases and variances that are difficult to quantify analytically. It has become popular in recent years to compute limiting bounds on the variance of these nonlinear estimators, since these bounds are usually much easier to obtain. A major problem, however, is that the bounds are only guaranteed to converge to the true variance of the estimator under sufficiently high signal-to-noise ratio (SNR). By applying higher order asymptotics, general expressions are obtained for the first-order bias and second-order variance of a general maximum-likelihood estimate. These expressions are applied in the matched field localization of a source in a shallow-water waveguide. The results quantitatively show that the Cramer–Rao bound provides an unrealistically optimistic estimate of the true variance in many practical scenarios, and the bias can be significant as the SNR passes below 0 dB.
Broadband adaptive matched field processing with modal filtering
Authors: Zurk Lisa M. , Lee Nigel , Ward James
Published: July 2002

This paper will demonstrate 3D localization of a moving, broadband source in a shallow water channel using adaptive matched field processing (AMFP) with modal filtering. The adaptation is desirable to mitigate the high sidelobes of the conventional processor, but it also introduces the requirement for long observation times, which can be difficult to satisfy for moving sources. Rank reduction can be achieved through modal preprocessing by exploiting the sparsity of propagating modes. In addition, the modal decomposition provides a mechanism for filtering the signatures of surface interferers from those of a submerged source. Results will be presented that demonstrate rejection of surface interference as well as quantifying the relationship between localization accuracy and the size of the modal subspace. The acoustic data was obtained during the Santa Barbara Channel Experiment (SBCX) which employed a 150-hydrophone volumetric array consisting of five vertical line arrays (VLAs) instrumented for element localization. The VLAs fully spanned the 209-m water column and allowed accurate modal decomposition. The MFP results will be presented for exercises involving a research vessel, the Acoustic Explorer (AX), towing an acoustic source. The results of broadband AMFP show accurate localization of both the towed source and towship.
An evening with the art and science of music: The families of musical instruments: Physics and performance
Authors: Hansen Uwe J. , Pyne James M.
Published: July 2002

During this tutorial we hope to communicate some of the enjoyment associated with musical acoustics by presenting musical examples along with scientific concepts. During each segment of the presentation, the relevant musical instrument will be introduced, and at the conclusion of each section, the piece of music performed will feature the appropriate instrument family. Physics principles related to tone generation, instrumental timbre, pitch change, and amplification will be discussed. Musical examples will be performed by The Ohio State University String Quintet, Paul Robinson, Coordinator; Michael Davis, violin; Laurel Butler, violin; Edward Adelson, viola; William Conable, cello; and Paul Robinson, bass; by The Ohio State University Woodwind Quintet, Katherine Borst Jones, coordinator; Katherine Borst Jones, flute; Robert Sorton, oboe; Robert Jones, clarinet; Christopher Weait, bassoon; Heidi Wick, horn; by The Ohio State University Brass Ensemble, James Akins, coordinator; William Campbell, trumpet; Peter Gibbons, trumpet; Joseph Duchi, trombone; James Akins, tuba; by Steven Glaser, piano; and by Michael Bump, percussion. For the gala conclusion, The Ohio State University Chamber Orchestra will bring all instrument families together.
The dispersion and attenuation of body waves in a transversely isotropic porous medium including the effect of pore shape
Authors: Liu Yinbin
Published: July 2002

Based on Biot’s theory of a general anisotropic porous medium [J. Appl. Phys. 33, 1482–1498 (1962)] and the dynamic permeability formula given by Johnson et al. for an isotropic medium [J. Fluid Mech. 176, 379–402 (1987)], we derived analytic expressions for the velocities and attenuations as functions of frequency for the quasi-P1 wave, quasi-P2 wave, quasi-SV wave, and SH wave in a transversely isotropic porous medium. Numerical results are given for one set of material parameters and compared with Schmitt’s results [J. Acoust. Soc. Am. 86, 2397–2421 (1989)] based on an alternative theoretical approach. The calculated results show that the phase velocities for quasi-P1 wave, quasi-SV wave, and SH wave are not sensitive to the pore shape, and the attenuations for four kinds of waves and the phase velocity for quasi-P2 wave are sensitive to the pore shape in the region of near and above threshold frequency.
Estimation of bottom parameters in shallow water using interference pattern in frequency domain
Authors: Katsnelson Boris , Grigoryev Valery , Petnikov Valery
Published: July 2002

A method of data inversion for geoacoustic parameters of bottom using FM acoustic signals is presented. The experiment was conducted at the stationary track between two ships. The source radiated linearly modulated signals within the band 25–95 Hz. Frequency spectra of received signals are taken as input data for application of the Matched Field Tomography (MFT) method. For estimation of bottom parameters we compare the experimental and model interference patterns in frequency domain. A new element in our approach (for MFT-method) is modeling of the bottom using a two-components model: water plus mineral particles. The main parameter (used as one of the matching parameters), i.e., the characterizing sediment is porosity, sound speed and density of bottom can be expressed through porosity. Two mechanisms of bottom losses are considered: literally absorption-transformation of sound energy into heat (linearly depending on frequency), and volume scattering within bottom (depending on frequency as power function with the degree determined by dominating types of scatterers). As a result of MFT bottom parameters are estimated. It is shown that on the low-frequency (less than 40 Hz) bottom absorption dominates on the other side, for more the high-frequency loss in sediment is conditioned by volume scattering. [Work supported by RFBR, Grant 97-05-64878.]
On the phase speed and attenuation of an interface wave in an unconsolidated marine sediment
Authors: Buckingham Michael J.
Published: July 2002

The phase speed and attenuation of the interface wave at the seawater–sediment boundary are obtained by solving the characteristic equation for one of its complex roots. The characteristic equation itself is derived on the basis of a recently developed theory of wave propagation in porous media. Central to the theory is the stress relaxation that occurs when mineral grains slide against one another during the passage of a seismic wave. This type of stress relaxation is characterized by material response functions for compressional and shear waves of the form h(t)∝t−n, where t is time since the sliding began and n is a small positive number. The phase speed of the interface wave relative to that of the shear wave depends weakly on the grain size, increasing from about 85% for fine-grained silts and clays to 90% for coarse sands. The loss tangent of the interface wave, βi, is found to be independent of the mechanical properties (grain size, porosity, and density) of the sediment, and is the same as that for the shear wave: βi≈0.04. Since the loss tangent and phase speed are, in effect, independent of frequency, the attenuation coefficient of the interface wave scales as the first power of frequency. It turns out that the characteristic equation for the interface wave, as derived from the intergranular stress-relaxation mechanism, is exactly the same as if the sediment had been treated as an elastic solid. However, the elastic description fails to account for the grain-size dependencies exhibited by the compressional and shear waves. These dependencies emerge naturally from the stress-relaxation model.
Effects of age and L1 use on native Italian speakers’ perception of English vowels
Authors: Flege James E. , McKay Ian R. A.
Published: July 2002

This study examined the categorial discrimination of pairs of Canadian English vowels (/i/–/ɪ/, /ɪ/–/ɛ/, /eɪ/–/ɛ/, /ɛ/–/æ/, /eɪ/–/ɪ/, /ɒ/—/ʌ/, /æ/–/ʌ/, /ɚ/–/ʌ/, /eɪ/–/i/) by groups of native Italian speakers who arrived in Canada at average ages of 7.6 and 19.5 years. Half of the 36 early and the 36 late bilinguals reported using Italian relatively seldom (mean=8%) or often (mean=48%). The subjects clicked ‘‘1,’’ ‘‘2,’’ or ‘‘3’’ to indicate the serial position of an odd item out, or ‘‘no’’ to indicate hearing three physically different instances of a single category. The discrimination (A′) scores were significantly higher for early rather than late bilinguals, and for bilinguals who used Italian seldom rather than often. The lack of a two-way interaction indicated that the L1 use effect was comparable for the early and late bilinguals. The ‘‘Early-High Use’’ group obtained lower scores than the native English comparison group for one constant (/ɒ/–/ʌ/) but the ‘‘Early-Low Use’’ group did not differ from the native English group for any contrast. The results suggest that both the state of development of the L1 phonetic system at the time L2 learning commences and language use influence the accuracy with which L2 vowels are perceived.
The effect of speaking rate on vowel production in Parkinson’s disease
Authors: Tjaden Kris
Published: July 2002

Kinematic and acoustic descriptions of articulatory characteristics in Parkinson’s disease (PD) generally are consistent with reports of hypokinesia and bradykinesia in the limbs. That is, articulatory movements tend to be underscaled and produced at slower than normal rates in comparison to healthy speakers, although movement duration may be preserved. Slowed speaking rate is one therapy technique used for improving the adequacy of speech production in PD. The assumption is that the slowed rate allows for more extensive articulatory displacements, thereby increasing the acoustic-perceptual distinctiveness of phonetic events. Few studies have quantified articulatory changes associated with speaking rate variation in PD, however. The present study examined the effect of speaking rate on vowel production for individuals with PD and healthy controls. Participants read a passage at habitual, slow, and fast rates. Segment durations, F1, and F2 midpoint frequencies for the vowels /i/, /ɑ/, /u/, and /ae/ were measured. Vowel space area was calculated for each speaker’s habitual, fast, and slow reading rate. The change in vowel space area was related to the magnitude of speaking rate change across rate conditions for both groups. Vowel space areas for PD and healthy speakers also were compared for each rate condition. [Work supported by NIH.]
Effects of masker harmonicity on masked threshold
Authors: Treurniet William C. , Boucher Darcy R.
Published: July 2002

The role of masker harmonicity in auditory masking is not yet fully understood. This paper compares the effect of harmonic and inharmonic maskers on the simultaneous masked thresholds of narrow bandwidth noise probes using a three-alternative, forced-choice method. The harmonic masker had an 88-Hz fundamental and 45 consecutive partials (random starting phases). The inharmonic masker differed in that the partial frequencies were adjusted to nearby prime numbers. Maskers were presented at several levels, and the probe at several frequencies. Thresholds were consistently lower for the harmonic masker (4–8 dB). The masking release persisted when masker and probe bandwidths were equal, so it is not due to comodulated auditory filter outputs. The difference between maskers disappeared when the harmonic partials were separated by more than 176 Hz, suggesting that the effect may be related to critical bandwidth. Further, the threshold of noise probes located between two partials was always lower for the harmonic masker. However, the threshold for a tonal probe at the frequency of an omitted partial was higher with the harmonic masker than with the inharmonic masker. The results are consistent with a harmonic template model that proposes inhibition at the template frequencies and disinhibition between those frequencies.
Noncontact ultrasonics for materials nondestructive evaluation
Authors: Lanza di Scalea Francesco , Green Robert E.
Published: July 2002

Recent advances in ultrasonic techniques for remote and noncontact nondestructive evaluation of structural materials will be presented. The principles and techniques of the laser generation and detection of ultrasonic waves in opaque solids will be reviewed. A laser-based beam-steering C-scan system will be described, along with a novel stabilization procedure for ultrasound detection by a confocal Fabry–Perot interferometer which appears to be more effective than previous approaches for high-sensitivity measurements in beam-steering scan applications. A hybrid system which is based on laser generation of narrow-band acoustic surface waves and their detection by gas (air) -coupled transduction will also be presented. This system uses fiberoptic light delivery which enhances its flexibility and remoteness from the test piece. The main issues governing the efficient coupling of high-power laser light into optical fibers will be discussed. An improved theory for the laser generation of narrow-band surface acoustic waves by the spatial modulation technique will be outlined and the effect of the number of illumination sources on the bandwidth of the generated wave will be assessed experimentally and theoretically. Finally, the suitability of the hybrid system for the intelligent control of the tow-placement process of advanced thermoplastic composites will be demonstrated.
Robustness of a ray travel-time inversion approach
Authors: Lu I-Tai
Published: July 2002

The robustness of a ray travel-time approach is studied using simulated data in both shallow waters and Arctic oceans. Effects of travel-time measurement error, sound speed profile mismatch, and source/array parameters mismatch on the solution accuracy are quantified. The approach is then employed to analyze the data generated by the first two SUS shots in the ICESHELF-89 experiment. Source location, array depth, array tilting angle, sound speed profile, and bathymetry are characterized.
Sound field modeling in streets with a diffusion equation
Authors: Picaut J. , Simon L. , Hardy J.
Published: July 2002

By assuming that the surface irregularities of the building facades are adequate to produce diffusion in streets, a diffuse sound field model using the mathematical theory of diffusion is used to predict the sound propagation and its reverberation in rectangular streets. This model, developed to predict the sound field in rooms with diffusely reflecting boundaries, is applied in this paper to urban acoustics. A 3D diffusion equation is derived for the sound energy density and solved for time-varying sources and in steady state. A diffusion parameter is introduced to characterize the amount of diffusion in the street. An exchange coefficient depending on the absorption coefficient is also used to take into account the wall absorption. When the diffusion coefficient is rightly chosen, the predicted reverberation times and sound attenuations are in accordance with measurements in a scale model of a street.
Integrality of nasalization and F1. II. Basic sensitivity and phonetic labeling measure distinct sensory and decision–rule interactions
Authors: Macmillan Neil A. , Kingston John , Thorburn Rachel , Walsh Dickey Laura , Bartels Christine
Published: July 2002

In vowel perception, nasalization and height (the inverse of the first formant, F1) interact. This paper asks whether the interaction results from a sensory process, decision mechanism, or both. Two experiments used vowels varying in height, degree of nasalization, and three other stimulus parameters: the frequency region of F1, the location of the nasal pole/zero complex relative to F1, and whether a consonant following the vowel was oral or nasal. A fixed-classification experiment, designed to estimate basic sensitivity between stimuli, measured accuracy for discriminating stimuli differing in F1, in nasalization, and on both dimensions. A configuration derived by a multidimensional scaling analysis revealed a perceptual interaction that was stronger for stimuli in which the nasal pole/zero complex was below rather than above the oral pole, and that was present before both nasal and oral consonants. Phonetic identification experiments, designed to measure trading relations between the two dimensions, required listeners to identify height and nasalization in vowels varying in both. Judgments of nasalization depended on F1 as well as on nasalization, whereas judgments of height depended primarily on F1, and on nasalization more when the nasal complex was below than above the oral pole. This pattern was interpreted as a decision–rule interaction that is distinct from the interaction in basic sensitivity. Final consonant nasality had little effect in the classification experiment; in the identification experiment, nasal judgments were more likely when the following consonant was nasal.
Ultrasonic absorption in critical binary mixture of perfluoromethylcyclohexane and carbon tetrachloride
Authors: Abdelraziq Issam R.
Published: July 2002

The results of ultrasonic absorption and velocity measurements for the system perfluoromethylcyclohexane-carbon tetrachloride are presented. In addition, viscosity measurements were made. Ultrasonic absorption at 5, 7, 10, 15, 21, and 25 MHz, above critical temperature Tc, is analyzed using the dynamic scaling theory of Ferrell and Bhattacharjee. The values of α/f2 vs f−1.06 show a good agreement with the theory. The experimental values of α/αc for the binary mixture are compared to the scaling function F(ω*).
The reconstruction of a spatially incoherent two-dimensional source in an acoustically rigid rectangular cavity
Authors: Wendoloski J. C.
Published: July 2002

This paper applies Green’s function modal expansion techniques to inverse source problems within an acoustically rigid rectangular cavity. In particular, solutions are developed for the reconstruction of a random spatially incoherent distributed source and a deterministic point source by using pressure-field measurements on adjacent walls. Such problems have seemingly not been addressed previously. Several example problems are studied in this paper. As is characteristic of inverse problems in general, numerical instabilities are encountered in the example problems addressed in this paper. These are linked to the notion of compactness in the forward operator, and dealt with using magnitude regularization and projections onto convex sets. The behavior of the example problems studied in this paper greatly deteriorates at frequencies near cavity resonances, particularly low frequency resonances (i.e., with ka≲2π, where a is the smallest cavity dimension). Other results concerning the example problems are also given. A proof of compactness of an infinite rank version of the type of operator used in this paper is given in the Appendix. This proof implies that the convergence of the Green’s function modal expansion in the kernel of the forward problem is related to the instability of the inverse problem. This implies that, if it suffices to know an integral of the source profile rather than the actual profile, the problem becomes more stable.
An energy-conserving spectral solution
Authors: Collins Michael D. , Schmidt Henrik , Siegmann William L.
Published: July 2002

An energy-conserving spectral solution is derived and tested. A range-dependent medium is approximated by a sequence of range-independent regions. In each region, the acoustic field is represented in terms of the horizontal wave-number spectrum. A condition corresponding to energy conservation is derived for the vertical interfaces between regions. The accuracy of the approach is demonstrated for problems involving sloping ocean bottoms. The energy-conserving spectral solution is less efficient than the energy-conserving parabolic equation solution, but might be suitable for generalization to problems involving elastic bottoms.
The quasistatic approximation for a cracked interface between a layer and a substrate
Authors: Pecorari Claudio , Kelly Piaras A.
Published: July 2002

Heuristic in nature, the quasistatic approximation (QSA) describes the interaction of ultrasonic waves with imperfect interfaces by modeling the interfacial imperfection as distributions of springs and masses. The QSA does not provide any relationship between the interfacial stiffness constants and the micromechanics of the defects. The aims of this paper are threefold. First, a derivation from first principles of the QSA boundary conditions on a cracked interface is presented. Relationships linking the interfacial constants to the mechanical and geometrical properties of the distributed cracks are also obtained. Second, the stiffness dependence of a cracked interface between a layer and a substrate on the layer thickness is investigated. It is shown that the interfacial stiffnesses cannot be regarded as intrinsic properties of the interface, but they may also depend on the structural properties of the hosting system. Finally, the effect of the thickness dependence of the interfacial stiffnesses on the phase velocity of the lowest mode supported by the layered structure is investigated.
Acoustic characterization for quality or damage evaluation in concrete structures
Authors: Tavossi Hasson M.
Published: July 2002

Concrete structures such as building columns, parking platforms, concrete highways, and bridges are under continuous action of two major types of cyclic stresses. First, thermal stress cycles due to seasonal temperature variations, resulting in cyclic thermal expansion and contraction. Second, mechanical stress cycles due to cyclic load variations; for example, resulting from the passage of a vehicle on a concrete platform. The cyclic stress, after a certain number of cycles, causes damage in concrete by fatigue. In this study, fatigue damage in concrete is evaluated by acoustic techniques, using wave speed and attenuation. Acoustic sensors of 50-kHz center frequency are coupled to the concrete, as transmitter and receiver, to evaluate concrete quality after concrete samples are subjected to thermal stress cycles. Results obtained in the laboratory will be presented, showing a significant weakening of the concrete strength after only a few stress cycles. The cyclic stress causes a significant drop in acoustic wave speed of the concrete, represented by a low value of its Youngs modulus. A quantitative relationship between fatigue damage and acoustic characteristics of concrete can be established, to evaluate the quality of the concrete structures.
Improvement of one- and two-layer liner design with bias flow
Authors: Follet Jesse Ian
Published: July 2002

The coupling of the resistance and reactance in acoustic liners has in the past limited aircraft engine liner design performance. This is due to the parametric dependence of the impedance on the perforated sheet geometry and cavity depths both having a significant effect on both parts of the impedance. For normal incidence liner impedance, designing a liner with its reactance approaching zero and resistance approaching unity is essential to the goal of producing maximum broadband absorption. Introducing a mean flow through the liner has shown that the liner resistance can be changed with minimal effect on the reactance. Liner geometry can be designed to achieve a broadband reactance that is as close to zero as possible. The resistance can then be increased to near unity by allowing a mean bias flow through the liner to produce the maximum broadband absorption. With sufficient modeling of liner impedance, an optimization routine can be used to find the liner characteristics that produce maximum absorption over a broad range of frequencies and sound-pressure levels. It will be shown that using bias flow can improve normal incidence liner absorption by 17% for single layer liners and 7% for double layer liners.
Partitioning, substructuring, and imposition of impedance: Are they the same?
Authors: McCoy John J.
Published: July 2002

Formulation partitioning, substructuring, and the imposition of an impedance operator, or DtN map, all refer to solution methods with the same purpose. This is to distinguish those coordinates necessary for describing the response of a structure, which are not directly forced by an external agent, and to eliminate these as primary variables in a reduced formulation. It is increasingly common to encounter use of the three terms interchangeably. This raises the question. Are the solution methods identical? Fundamental differences are identified and the significance of these differences is discussed.
The vowel spaces of normal-hearing listeners and patients with cochlear implants
Authors: Harnsberger James D. , Pisoni David B. , Svirsky Mario A. , Kaiser Adam R. , Wright Richard
Published: July 2002

Cochlear implant (CI) users show substantial individual differences in their ability to understand speech in general, and vowels in particular. These differences may result from widely different abilities in identifying formant frequencies or in adapting to the more basal than normal spectral information presented by the implant. In this study, we administered a vowel perception test, using a method-of-adjustment (MOA) paradigm, to 8 CI users and 43 normal-hearing listeners. The MOA vowel test consisted of 330 steady-state synthetic vowel stimuli, varying in F1 and F2, arranged in a visual two-dimensional grid. Subjects were asked to label and rate on a 7-point scale those stimuli that matched the vowels contained in ten visually-presented words, ‘‘heed,’’ ‘‘hid,’’ ‘‘aid,’’ ‘‘head,’’ ‘‘had,’’ ‘‘hut,’’ ‘‘odd,’’ ‘‘whod,’’ ‘‘hood,’’ ‘‘owed,’’ and ‘‘odd.’’ Plots of subjects’ responses for all ten words constituted the vowel spaces of the subjects. With one exception, no systematic shift was observed across all vowel categories of CI users, suggesting that these subjects were able to adapt completely to the spectral shift introduced by the implant. However, the CI users’ spaces differed substantially from normal vowel spaces in terms of the relative size of the vowel categories and their location in perceptual space.
Confidence ratings in auditory–visual speech perception
Authors: Clement Bart R. , Erickson Sarah K. , Jin Su-Hyun , Carney Arlene E.
Published: July 2002

In an earlier report, Carney et al. [J. Acoust. Soc. Am. 106, 2270 (1999)] showed that the perception of the McGurk effect, the result of a visual syllable biasing the perception of a simultaneously presented auditory syllable, was affected by the use of multiple talkers. In addition, individual listeners could be strongly auditory in their perception, even when a visually biasing stimulus was present. During the original experiment, listeners were asked to rate each of their perceptions in the auditory-only (AO), visual-only (VO), and auditory–visual (AV) modes for syllabic stimuli. Listeners were very confident of their perceptions for bilabial stimuli in the VO mode but not for alveolar or velar stimuli. Confidence ratings were also high for all AO stimuli and for AV stimuli for matching visual–auditory tokens. However, confidence ratings varied for tokens with mismatched A and V stimuli. Some individual listeners were always confident in their perception regardless of speaker or condition. Other listeners varied in confidence with speaker and condition. Across listeners, certain talkers evoked different ratings of confidence as well. Results support the notion of a graded perception of bimodal stimuli. [Work supported by NIDCD.]
Subjective relevance of objective measures for spatial impression
Authors: Wang Lily M. , Gade Anders C.
Published: July 2002

Several objective measures have been proposed to describe the feeling of spatial impression in concert halls, including Lateral Energy Fraction (LF) and Interaural Cross-Correlation Coefficient (IACC). However, previous studies have shown that LF and IACC values did not highly correlate with each other at individual seat positions in real halls [J. S. Bradley, J. Acoust. Soc. Am. 96, 3525–3535 (1994)]. To investigate the listener envelopment aspect of spatial impression further, subjective paired-comparison tests have been run using signals which have various values for LF, early IACC (from 5–80 ms), late IACC (from 80 ms–1 s), and late lateral relative sound level (GLL). Another proposed measure, called Interaural Level Fluctuations (IALF), has also been included, which is based on the rate of change over time of the level difference between the ears. The binaural test signals were generated by the room acoustics simulation program ODEON, using four different musical motifs, and were presented to test subjects via headphones. Results from the experiments are presented. [Work supported by ASA Hunt Postdoctoral Research Fellowship.]
Some acoustic considerations in the use of Kerto-wood in the construction of Sibelius Hall
Authors: Storch Christopher A.
Published: July 2002

Sibelius Hall is a 1300-seat concert hall and congress center which was built by the City of Lahti, Finland, with the sponsorship of the Finnish wood industry. The wood industry’s support in this construction project was conditional based on using wood in new and experimental ways, not only as a finish material, but as a structural material. A proprietary product called Kerto-wood was used in a wide variety of structural and finish applications. Sand-filled Kerto-wood panels 300 mm thick were used in the slanted exterior walls. Details of the sand-filled panels’ construction, the joining details, and the transmission loss testing of the assembly will be discussed. Prefabricated Kerto-wood elements were also used to construct the ceiling, balconies, and reverberation chamber doors. Discussion of the reflective properties will also be presented.
Adjustment of reverberation in the rehabilitation of theaters. Its application to the architectural patrimony of theaters in Andalusia, Spain
Authors: Leon Angel Luis , Navarro Jaime , Sendra Juan Jose
Published: July 2002

One hundred years after its formulation by W. C. Sabine, the reverberation time continues to be, we feel, the one most useful indicator for architects when undertaking the rehabilitation of theaters in which the main objective is to obtain good acoustic conditions. The reverberation time is easily quantifiable during the planning phase, thus proving to be of great interest in the process of theater design. The adjustment of reverberation times in a theater to the different frequencies at intervals regarded optimum is considered to be an indispensable determinant, though not in itself sufficient, to obtain a good acoustics. This adjustment is intimately related to the decisions proper to the work of the architect in interior design, such as the election of surface materials or the volume of the locale. The authors of this study, who have participated in the rehabilitation of 35 theaters in Andalusia as acoustic consultants, propose to relate the results of their work with the different proposals of the principal researchers in room acoustics, about optimum values of reverberation, with the aim of obtaining a series of conclusions to offer to professionals of rehabilitation.
Acoustics of rototoms
Authors: Rossing Thomas D. , Kwon Juyong
Published: July 2002

Rototoms are single-membrane drums that can be quickly tuned by rotating the drum. The sound spectra and modal shapes recorded holographically show membrane modes quite similar to those observed in other drums, such as tom-toms, snare drums, and timpani. The sound is dominated by the fundamental radiated bathe (0,1) mode of vibration. The frequency ratio of the various partials changes with tension over the playing range of each drum, resulting in a changing timbre.
The acoustics of a symmetric free reed coupled to a pipe resonator
Authors: Cottingham James P.
Published: July 2002

The Asian free-reed mouth organs employ symmetric free reeds mounted in resonating pipes, with the reed vibration strongly coupled to the pipe resonance. The sheng, the sho, and the khaen use a single pipe for each reed, constructed so that the pipe resonance frequency is fairly close to the natural frequency of the reed. The playing frequency is typically slightly above the resonant frequencies of both the reed and the pipe. The free-reed pipe with finger holes (known in China as the bawu) employs a pipe resonator of variable effective length in which both the pipe resonance and sounding frequency are normally well above the natural reed frequency, resulting in a striking change in tone quality. The operation of these instruments has been studied both experimentally and theoretically, with particular attention to the coupling of the reed vibration with the pipe resonator. Experimental measurements include both studies of reed vibration and impedance measurements of the pipes. In general, the experimental results can be shown to agree with the predictions of simple theoretical models.
The influence of upstream geometry on the activation pressure of free and restricted reed configurations
Authors: Vermeulen Marius O. , Wessels Jabus A. , von Backstrm Theodore W.
Published: July 2002

This paper describes a computationally efficient algorithm for the automatic calculation of reed activation pressure. The method was evaluated using both free and restricted reed configurations which were not connected to any external air column. It is shown how the reed activation is influenced by intrinsic factors such as rounded and minute burrs on the edge of the reed as well as extrinsic factors such as upstream geometry of the experimental apparatus. The introduction of constrictions in the flow path upstream from the reed resulted in marked changes in the activation pressure which was highly dependent on the length of the constriction. Expansions of the same magnitude, however, had less influence on the reed activation pressure.
Systematic investigation on acoustic-to-seismic responses of landmines buried in soil
Authors: Sabatier James M. , Xiang Ning
Published: July 2002

Recently, acoustic-to-seismic coupling has been successfully applied to landmine detection [Sabatier and Xiang, J. Acoust. Soc. Am. 105, 1383 (1999); 106, 2143 (1999)]. When airborne sound penetrates the surface of ground it is refracted towards the normal. If a landmine is buried below the surface of an insonified patch, the transmitted waves will be scattered or reflected, resulting in increased ground surface vibrational amplitudes. These distinct acoustic-to-seismic coupled vibrational changes are sensed using a scanning laser Doppler-vibrometer (LDV) device. To better understand this mine detection phenomenon, the present work is a systematic investigation of the acoustic-to-seismic response to different types of mines in different soil types and at different burial depth has been conducted. [This work is supported by U.S. Army Communications-Electronics Command.]
Modeling across-channel processing of amplitude modulation
Authors: Ewert Stephan , Verhey Jesko , Kollmeier Birger , Dau Torsten
Published: July 2002

In typical modulation detection experiments, a sinusoidal signal modulation is applied to broadband noise as the carrier. In such conditions, the carrier envelope at the output of different peripheral auditory channels might be considered as nearly uncorrelated while the signal modulation is coherent across channels. Models of auditory processing often combine signal information optimally in terms of signal detection theory, assuming independent ‘‘observations in different auditory channels.’’ On the other hand, various experiments demonstrated that modulations applied to spectrally separated carriers can interfere, indicating that (prior to the decision stage) amplitude modulation is not processed independently across carrier frequency in these conditions. In the present study, modulation detection and modulation masking conditions were examined where the signal and the masker modulation were applied either to the same carrier or to spectrally separated carriers. Simulations are presented based on an envelope power spectrum model [Ewert and Dau, J. Acoust. Soc. Am. (submitted)], which calculates the envelope power in the transfer range of a modulation filter tuned to the signal-modulation frequency. Within the model, different strategies of combining across-channel envelope information, as well as the influence of peripheral filtering and compression, are considered. [Work supported by the Deutsche Forschungsgemeinschaft.]
Acute effects of nicotine on physiological responses of the auditory systems of nonsmokers
Authors: Harkrider Ashley W. , Champlin Craig A.
Published: July 2002

The role of cholinergic mechanisms in the auditory system was investigated by assessing the acute effects of nicotine, a cholinergic drug, on aggregate responses within the auditory pathway. In a single-blind procedure, evoked potentials (auditory brainstem, middle-latency, long-latency, steady-state responses) and electroencephalograms were measured from 20 normal-hearing, nonsmokers (10 male) under two conditions (nicotine, placebo). After the drug session, plasma tests indicated a subject’s nicotine concentration. Results indicated that transdermal administration of nicotine to nonsmokers does appear to acutely affect the transmission of acoustic information. The measures most affected by nicotine administration likely originate from the midbrain and cortex and are believed to involve processing of auditory information related to vigilance and the screening of sensory input. The effects of nicotine on evoked potentials or the electroencephalogram do not appear to be dependent on the sex of the subject or the hemisphere from which the responses are measured. [Work supported by AAA and NIDCD.]
Planning and forming articulatory movements from phoneme-specific representatives
Authors: Okadome Takesi , Honda Masaaki
Published: July 2002

A computational model of sensorimotor planning of speech production is described. The model uses phoneme-specific representatives to predict the trajectories of articulatory movements for continuous speech. As phoneme- specific representatives, the model uses acoustics for the vowels and articulatory features for the consonants. The acoustics are represented by LPC cepstral segments. The articulatory features of the consonants are those of the kinematics of the articulators; that is, the position and velocity of the articulator. The model first recovers the kinematic features from the acoustic segment for the vowels using the acoustic-to-articulatory inverse mapping method [S. Suzuki et al., Proc. ICSLP 6, 2251–2254 (1998)]. Using the kinematic features of the vowels together with those for the consonants, the model determines the minimum-acceleration trajectory that coincides with the extremum of the time integral of the square of the magnitude of acceleration of the articulator [T. Okadome et al., Proc. IEEE SMC 2, 469–474 (1999)]. The model predicts both the qualitative features and quantitative details experimentally observed.
The application of segment-based orthogonal transform in signal bias removal
Authors: Wang Wern-Jun , Huang Eng-Fong , Chen Sin-Horng
Published: July 2002

The iterative technique for signal bias removal (SBR) to minimize the effects of corrupted speech with unknown noisy sources was proposed for robust speech recognition. The SBR method was applied by considering a multiplicative spectral bias or equivalently, an additive cepstral bias. Two problems of this approach can be found. One is that it needs sufficient iterations to attain better results and the other difficulty is the lower accuracy of bias estimation. To overcome these drawbacks, a novel approach of SBR incorporated with orthogonal transform is adopted in this study. Instead of the conventional frame-based process, this method is a segment-by-segment approach. The basic idea of this approach is that the segment constituted by any feature element will be modeled using orthogonal transform coefficients. Owing to the characteristics of orthogonal transform, the high-order coefficients are bias-free and only the zeroth order coefficient is bias-corrupted. The high-order coefficients can therefore be used for bias estimation and the real bias will be deduced from the zeroth-order coefficient. Effectiveness of the method was confirmed by an experiment of multispeaker noisy continuous Mandarin speech recognition. The significant improvement on computation and recognition rate can be achieved by this method.
Exploiting target motion for active matched-field depth estimation
Authors: Hickman Granger , Krolik Jeffrey
Published: July 2002

This paper concerns the use of complex multipath propagation for discriminating the depth of a moving target with a low-frequency active sonar. Although matched-field processing techniques, which exploit full-wave modeling of multipath propagation, have been previously demonstrated in passive sonar applications, their use in active sonar has been precluded by uncertainty in the complex backscattering characteristics of the target. In this paper, a matched-field technique is proposed which exploits changes in the complex moving target return seen between consecutive sonar pings at a horizontal receive array. Because the method exploits only changes in the coherent combination of multipath arrivals, it does not require a priori knowledge of the target backscattering characteristics assuming its aspect is only slowly changing from ping to ping. In this paper, simulation results are presented which are modeled after a realistic Mediterranean scenario taken from the Shallow-Water Active Classification Experiment performed in November 1995. Matched-field depth estimation simulation results indicate that target depth accuracies of better than 20% of the channel depth can be achieved at ranges of 10 to 15 km. [Work supported by ONR.]
Multibeam bathymetry and Deep Tow sidescan sonar surveys SW of San Clemente Island, CA
Authors: de Moustier Christian
Published: July 2002

In March 1999, about 170 square nm of bathymetry were mapped from the 40- to 700-m contour lines using a 50-kHz Elac BottomChart multibeam echo-sounder temporarily installed aboard Scripps’ R/V NEW HORIZON. This survey provided the base map for a near-bottom 110-kHz sidescan sonar and 4-kHz subbottom profiler survey with the Marine Physical Lab. Deep Tow package. Notable seafloor geological features include a broad terrace, left over from the last glacial low sea level stand and sloping gently from the island’s shore to the 120-m depth contour, canyons and sediment aprons below, steep rocky extensions of China Point (island’s southern-most point), and the sheer wall of the San Clemente Escarpment to the east. The sidescan sonar map has poor contrast over the sandy bottom along the island’s western shore, whereas the rock spurs off China Point and a number of erosional channels carving the slopes between 200- and 800-m depth correspond to areas of high acoustic backscatter. Deep Tow subbottom profiles along the southern slope provide evidence of erosional channels cutting through sediment bedforms that are presumably compressional side effects of the strike-slip faulting along the San Clemente Escarpment.
Object matching across vision and echolocation by dolphins and humans
Authors: Harley Heidi
Published: July 2002

Bottlenose dolphins can recognize objects across modalities, i.e., given a sample object visually or echoically, a dolphin can identify that object from among a group of alternatives in the second modality (echoic or visual, respectively). Dolphins may be able to perform this task, because (1) they can learn to associate their visual and echoic experiences of an object; (2) they can recognize an equivalence between their visual and echoic experiences through the detection of object features that are available to both modalities; (3) they can create a spatial-analog representation (an ‘‘echo-image’’) of an object based on its echoes. Data from a dolphin performing a three-alternative cross-modal matching task in which identical (object A to object A) or conditional (object B to object C) matches were reinforced suggest that the dolphin can perform this task based on a recognition of equivalence between his visual and echoic experiences; the dolphin consistently matched based on object identity regardless of reinforcement for conditional matches. Data from a cross-modal matching task with humans listening to slowed-down dolphin echoes and choosing from among photographs of objects suggest that it is possible to perform this task without echo imaging.