bluuebunny/crossref_metadata_2025 huggingface dataset:
Auditory memory in phonetic and nonphonetic judgments of vowels
Authors: Shigeno Sumi
Published: October 2005

The present study compares the magnitudes of context effects in the perception of phonetic and nonphonetic features of stationary vowels. The stimuli were synthetic vowels on the [u]-[a] continuum generated by varying stimultaneously F1 (442–586 Hz) and F0 (118–154 Hz). Thus vowel [a] had a higher pitch than [u]. Category boundaries were determined for the following three conditions: (1) isolated vowels presented in random sequence, (2) vowels with a preceding context stimulus [u], and (3) with white noise inserted between the context stimulus and the target stimulus. When the ISI between the context and the target was 2.0 s, the context effect was contrasted in the case of phonetic judgment, and its magnitude was reduced by the insertion of white noise. It was assimilated in the nonphonetic judgment, and its magnitude was increased by the insertion of noise. When the ISI was 0.5 s, the magnitude of the assimilation in the nonphonetic judgment was not increased by the insertion of noise. These results suggest that the reduction of contrast was not due to a decrement in auditory memory, which can be considered as a fast-decaying component.
Effects of syllable duration on the perception of Mandarin tones: A cross-language study
Authors: Blicher Deborah L. , Diehl Randy L. , Cohen Leslie B.
Published: October 2005

Mandarin syllables carrying a high-rising F0 contour (tone 2) tend to be produced shorter than those carrying a low-falling-rising contour (tone 3). It is suggested that, even for syllables with the same physical duration, the more complicated F0 structure of tone 3 makes it appear longer than tone 2. Talkers may therefore produce an actual length difference to enhance the apparent length difference. This hypothesis was tested by comparing perceptual judgments by native Mandarin and native English speakers on various series of Mandarin tones. A short-stimulus (350 ms) series and a long-stimulus (450 ms) series were synthesized for each of the syllables /bi/, /ba/, and /bu/. Each series was generated by incrementally interpolating the F0 contour between a tone 2 and a tone 3 exemplar, both of which were Mandarin morphemes or words. Subjects (both Mandarin- and English-speaking) were first trained with feedback to assign the short and long series-endpoint stimuli to two categories based on F0 contour alone. Next, subjects identified the entire stimulus series (both long and short) on the basis of the two training categories. For both Mandarin- and English-speaking subjects, a longer syllable duration shifted the labeling boundary reliably toward fewer tone 2 (i.e., more tone 3) responses. The parallel boundary shifts suggest that length variation enhances the perceptual distinction between tones 2 and 3, probably by reinforcing what is already a difference in apparent length. [Work supported by NINCDS.]
The neural coding of relational invariance in speech: Human language analogs to the barn owl
Authors: Sussman Harvey M.
Published: October 2005

This paper presents a brain-based perspective on the noninvariance problem in speech research, namely, that physically different auditory stimuli come to elicit an invariant perception of a phoneme category. Extrapolating from the sound localization system in the barn owl, two speculative human models are offered that account for the emergence of relational invariance for (1) bilabial and alveolar stop consonants across vowel contexts, and (2) vowel identity across speakers with different sized vocal tracts. The barn owl's extraction of interaural time differences (ITDs) to signal azimuth is based on disambiguating interaural phase information coded by frequency specific neurons. Only by spanning across a broad frequency spectrum can a neuronal functional array signal an unambiguous ITD to higher centers. A similar principle is invoked to model both stop consonant place invariance and vowel normalization in human speech processing. Formant manipulation metrics, capable of distinguishing contrastive phonemic categories, are described to illustrate the operational features of the modeling scheme.
Effect of vowel duration on the perception of syllable-initial /∫/ and /t∫/
Authors: Kluender Keith R. , Walsh Margaret A.
Published: October 2005

The duration of an adjacent vowel has been demonstrated to affect the judgment of consonant duration and, hence, phonetic identity. For example, syllable-initial stops can be distinguished from glides on the basis of transition duration and, when the following vowel is relatively long, longer transitions are required in order for a glide to be perceived. Apparently, the vowel provides a source of durational contrast, whereby a longer vowel makes the adjacent consonant seem shorter. This effect has been demonstrated for both speech and nonspeech signals [L. Diehl and M. A. Walsh, J. Acoust. Soc. Am. Suppl. 1 80, S125 (1986)], and is presumably grounded in a general auditory mechanism. In this study, the effect of vowel duration on perception of syllable-initial consonants is also demonstrated for fricatives and affricates. Frication duration is an important cue to this distinction, with longer durations yielding more /∫/ responses. Two series of edited natural tokens of /∫a/ and /t∫a/ were created in which frication duration varied from 100 to 210 ms. The duration of the following vowel was 204 ms for one series, and 358 ms for the other. With the longer vowel context, significantly longer frication was required to yield a /∫/ percept. Consistent with earlier findings for other consonantal distinctions, durational contrast occurred between the vowel and fricative. [Work supported by NINCDS.]
Perception of fluent and nonfluent speech in spontaneous utterances and spoken text
Authors: Homel Peter , Brighenti Laura
Published: October 2005

Modeled after Remez et al. [J. Acoust. Soc. Am. 77, 538 (1985)], this study measured the perceptual differences between spontaneous and read versions of sentences, where read versions were made to sound “spontaneous.” Subjects were required to distinguish between sentences selected from a recorded interview and versions of those sentences from a recording of the speaker reading a highly faithful transcript of the original interview (including emphasis, pauses, and dysfluencies). Sentences selected for the perception experiment were of two types: intact, well-formed fluent sentences and nonfluent sentences containing some minor dysfluency but which are otherwise well formed. Results showed that subjects performed at a level better than chance but lower than that found in Remez et al. Subjects also tended to show better performance for nonfluent sentences, in agreement with subjects' reports that timing and perceived anticipation of dysfluencies seemed to distinguish spontaneous and read versions. These results replicate and extend Remez et al., and point out the possible role that dysfluencies play in the perceived spontaneity of speech.
Effects of directed attention on the reliability of dichotic listening
Authors: Blood Ingrid M. , Blood Gordon W.
Published: October 2005

This investigation examined the performance of adult subjects on perception of dichotic CVs. Twenty subjects were tested over five separate sessions to determine the reliability of responses. Instructions utilized either free recall or directed listening to the right or left ear. The methods of analysis used were d′ (% RC − % LC), laterality equation (R − L/R + L × 100), percent of error (LE errors/total errors), and phi coefficient (R − LR + L[2T − (R + L)]). Results indicated that the right ear advantage remained consistent for the right, left, and no direct condition. Differences in dichotic performance were found over the fivesss trials.
Evaluating the intelligibility of different speech degradations using the ICAO spelling alphabet
Authors: Schmidt-Nielsen A.
Published: October 2005

A series of experiments was conducted using spelling alphabet words (ALFA, BRAVO, CHARLIE, etc.) to evaluate the intelligibility of several severely degraded voice communication conditions. Under severe speech degradation, standard consonant intelligibility tests such as the DRT and MRT are often not very helpful in predicting the actual usability of a particular voice system because consonant information is often so degraded that listeners must rely on other cues such as vowel identity, prosody, and context in order to understand the speech. The spelling alphabet is a small highly distinctive vocabulary that was designed to be robust in noise. Scores are compared with rhyme test (DRT) scores and with performance on a sentence verification task. The most frequently confused work pairs are compared across different types of degradation. For LPC with bit errors, confusions tend to be highly asymmetric (PAPA is frequently heard as ALFA, but the reverse confusion almost never occurs), whereas with noise degradation confusions are more likely to occur in both directions (e.g., ALFA-DELTA and DELTA-ALFA). Speech degraded with interrupted noise shows yet a different pattern of most frequent confusions and omissions.
On the modeling of self-oscillation in brass instruments
Authors: Yoshikawa Shigeru
Published: October 2005

It is recognized that the lips of brass players vibrate two-dimensionally, i.e., in parallel and perpendicularly to the direction of the air flow as the excitatory source. This two dimensionality gives two different models of lip motion in brass instruments: (1) the parallel model as a “reed striking outwards,” which is the reverse to the model of a woodwind reed as a “reed striking inwards” [N.H. Fletcher, Acustica 43, 63–72 (1979)], and (2) the perpendicular model as a “one-mass vocal cord striking laterally” [J. Saneyoshi, H. Teramura, and S. Yoshikawa, Acustica 62, 194–210 (1987)]. The phase difference between the lip displacement and the acoustic pressure acting on the lips, or the frequency difference between the antiresonance of the horn itself and the sound excited, can determine which model is actually dominant. This paper describes some attempts to find these quantities on a cylindrical pipe blown by lips without a mouthpiece. The discussion of the experimental results and the modeling of the lip vibration is presented after briefly explaining the differences between the regeneration theories based on the above models.
Computational study of brass instrument configurations
Authors: Dudley J. Duane , Strong William J.
Published: October 2005

Input impedance curves are computed for several bores related to brass wind instrument shapes, such as a cylinder, cone, French horn bell, “catenoidal bell,” some “bell + cylinder” combinations, and a complete French horn. The impulse response curve for each is obtained by performing a Fourier transform of the complex input impedance. These will be shown and discussed with respect to physical interpretations and interesting insights. A sinusoidal input volume velocity is then introduced, and the steady-state (sinusoidal) pressure response at the inlet is determined by convolving the velocity input with the impulse response. This is done for various frequencies, and the resulting pressure amplitudes are shown to be consistent with those of the impedance curve. An input volume velocity composed of several harmonically related sinusoidal components, approximating the output from a player's lips, is then introduced. The resulting pressure response is computed at the inlet of a French horn, whose resonant frequencies are quite harmonic. The same computations are then made for a relatively inharmonic system, and the results are compared to those for the French horn.
A flow-cytometric study on cultured cells after exposure to pulsed ultrasound
Authors: Maeda Kazuo , Kigawa Junzo
Published: October 2005

HeLa cells were cultured inside a flask that allowed ultrasonic penetration, and were exposed to 3, 5, or 10 μs wide experimental ultrasound, the intensity of which was measured by microbalance, though it will be further confirmed by the hydrophone technique. The exposure was made in a water bath for 15 min, and then the cells were analyzed with a Cytofluorograf 30H flow cytometer. The cell DNA distribution showed a change that was comparable to the effect of gamma-ray exposure, or a cytostatic agent after exposure to 5- or 10-μs SPTA 2.35 W/cm2 ultrasound, but no change was observed after the exposure to 3-μs pulsed ultrasound with the above-mentioned intensity, or after exposure to 10-μs 0.2 W/cm2 pulsed ultrasound. The results were similar to a study on the suppression of the cell growth curve after exposure to experimental ultrasound on JTC-3 cultured cells.
Acoustic streaming generated by surface oscillations
Authors: Thompson Charles , Mehta Vineet
Published: October 2005

An analysis of streaming in a oscillatory flow over a two-dimensional temporally and spatially varying boundary will be presented. This phenomenon plays an important role in transport of passive contaminants. Longuet-Higgins have shown the role played by Reynolds stress in producing drift in a viscous fluid. The modifications in streaming due to interplay between surface oscillations and the flow field affect the mass transport velocity. A primary objective in modeling the mammalian auditory system is an analysis of the fluid motion in the cochlea. The deflections of the basilar membrane, which produce the sensation of hearing, are coupled to the streaming flow. A theoretical model describing the fluid motion will be given. It will be shown that the dynamic behavior of the flow field is characterized by the parameters ε, a typical slope; R, the oscillatory Reynolds number; S, the Strouhal number; and α, the amplitude of the temporal variation. An analytic solution will be sought in terms of an expansion in ε. [Work supported by Analog Devices Professorship.]
Graduate acoustics at The University of Texas at Austin
Authors: Blackstock David T. , Busch-Vishniac Ilene J. , Hamilton Mark F. , Hixson Elmer L.
Published: October 2005

The study of acoustics at the University of Texas at Austin is quite broad. It includes physical acoustics, engineering acoustics, underwater acoustics, dectroacoustics, noise and vibration control, environmental acoustics, architectural acoustics, psychoacoustics, speech, audiology, linguistics, and musical acoustics. Not surprisingly, the program is spread over several departments. Engineering and physical acoustics is concentrated in the Mechanical Engineering and the Electrical and Computer Engineering Departments, with some activity also in the Physics Department, the Aerospace Engineering and Engineering Mechanics Department, and the Petroleum Engineering Department. Considerable research in hearing and speech is carried out in the Psychology, Linguistics, and Speech Communication Departments. Engineering and physical acoustics is stressed in this paper. Formal course work at the graduate level consists of 1 year of basic physical and engineering acoustics and several advanced one-semester courses, e.g., electromechanical sensors/actuators, nonlinear acoustics, underwater acoustics, ultrasonic engineering, noise control, and wave propagation in continuous media. Research is carried out in all these areas. In the last 8 years, 37 students in the various departments (in the College of Engineering and in Physics) have earned master's degrees with theses in acoustics, and 12 have earned Ph.D. degrees.
An automated vibration identification system for complex machinery installations
Authors: Esparcieux Ph.
Published: October 2005

Excessive vibrational levels on complex machinery installation, like a ship, may cause considerable annoyance in both the environment and the installation itself. Because noise and vibration specialists are not always available in all situations, an attempt has been made to proceed to a purely automated identification procedure. Attention has been focused on situations in which critical levels are established on crucial locations of the structure (the so-called “monitoring points”), rather than on the sources themselves. A vibration monitoring system that involves a careful transducer arrangement and an extensive data acquisition system is fitted on the installation. Prior knowledge of mounted equipment and dynamic characteristics of structural elements is necessary to constitute a description data base that is referred to by an expert system that supervises the entire procedure, including data acquisition and specific signal processing. Then, after a preselection of the suspected sources, the supervisor system controls a more detailed scrutinization that yields the final diagnosis of the fault of the installation. The paper presents a fully automated identification system that works on an installation fitted with 18 rotating machineries.
Biomuse: Musical performance generated by human bioelectric signals
Authors: Lusted Hugh S. , Knapp R. Benjamin
Published: October 2005

A new type of musical instrument is described which utilizes bioelectric signals to drive a keyboard synthesizer via standard musical instrument digital interface (MIDI) code. Electrical activity from muscle (EMG), brain (EEG), heart (EKG), and eye (EOG) is detected by small disk electrodes on the skin, analyzed by a digital signal processor, and used to control sound generation from the synthesizer. Signal processing algorithms are designed to extract useful control parameters from the given physiological signals. For instance, detection of amplitude changes in the EMG and spectral changes in the EEG can be used to generate MIDI commands. Applications for the device are discussed, such as dance generated music, musician self-mixed performances, and music production by the handicapped.
Least-squares and single-filter always-convergent iterative deconvolution of transient signals for correlation processing
Authors: Leclere James H. , Ioup George E. , Ioup Juliette W. , Field Robert L.
Published: October 2005

Correlation processing for distributed sensors is most accurate for short pulses and those whose autocorrelation is sharply spiked. For longer transient signals, multipath arrivals at each sensor have significant interference with each other, and it is difficult to identify individual arrival times. Deconvolution of the received signal to sharpen the transients is one method to decrease the overlap and increase the accuracy with which travel times can be identified. Deconvolution can also be applied after cross correlation to sharpen the autocorrelation of the transients. Least-squares deconvolution is the most commonly used approach for acoustic signals. It has the disadvantage of being computer intensive when filters for long transients are needed. An alternative approach, the single-filter application of the always-convergent iterative technique, is faster and provides variable control for noise. The two techniques are compared for actual underwater acoustic multipath transient signals. Single filter application of always-convergent iterative noise removal is compared to the use of a modified Blackman-Harris window for noise control.
Active noise control based on the inverse filtering of room acoustics
Authors: Miyoshi Masato , Kaneda Yutaka
Published: October 2005

A novel active noise control method based on an inverse filtering theorem MINT [M. Miyoshi and Y. Kaneda, IEEE Trans. Acoust. Speech Signal Process. ASSP-36(2), 145–152 (1988)] is described. According to this theorem, broadband random noise can be precisely controlled at N points (N = 1,2,…) in a room using N + 1 loudspeakers and FIR filters. Consequently, the proposed method creates a quiet zone around a given set of points. This method also has the unique property that, in a diffuse sound field, the power sum of the FIR filter coefficients is less than one. This property is employed in estimating the quiet zone attenuation. When broadband random noise is controlled at two points placed at an interval of λ/4 (where λ is the wavelength of the center frequency of the objective noise band), the estimated noise attenuation can be summarized as the following. (1) Noise attentuation of more than 14 dB is achieved at the middle of the points. (2) Over 6 dB of noise attenuation is achieved in a gourdlike quiet zone which is λ/2 long by λ/8 wide. (3) The sound-pressure level of broadband noise observed outside the quiet zone is, at most, 6 dB higher than the noise level when the noise is left uncontrolled. An experiment was conducted for controlling random noise in the range of 50–400 Hz at two points in a room in which the reverberation time was 0.5 s. The volume of the room was about 70 m3. The experimental results showed good agreement with estimations (1), (2), and (3).
An active noise control system by means of motional feedback without a microphone
Authors: Nishimura Yoshitaka , Usagawa Tsuyoshi , Ebata Masanao , Okda Josuke
Published: October 2005

A method for active noise control using a motional feedback system without any microphone is described. The impedance of an electroacoustic transducer can be controlled by motional feedback, and the noise in a duct can be reduced actively by adjusting the impedance of the transducer used for an additional sound source. The characteristics of the impedance of the transducer with the motional feedback and noise reducing effect of this system are analyzed, and they are measured using both analog filter implementation and a digital one. The results show that this system is effective in controlling the noise in a duct, but it is not applicable to a wide frequency range. The advantage of this system is that it does not need any microphone which has been a weak element in conventional active control systems under undesirable circumstances, such as high pressure, high temperature, dust, air flow, and so on.
Active noise absorption as an inverse source problem
Authors: Gan Woon S.
Published: October 2005

In an ordinary approach to three-dimensional active noise absorption (ANA) the degree of noise cancellation will increase with the increasing number of small secondary sources used. Here, a three-dimensional ANA is formulated as an inverse source problem and acoustical holography is used to realize the secondary (absorbing) sources. The advantage is that one does not have to approximate the number of secondary sources used to obtain identical field to the primary source which is a prerequisite for ANA. The use of generalized holography is proposed. Here, the generalized hologram is constructed by recording the field and its normal derivative over a closed surface surrounding the primary noise source. This gives the Huygens' sources. The required secondary sources are obtained by the reconstruction of the generalized hologram, by allowing the recorded field and normal derivative to backpropagate into the space region containing the primary source. To test the theory, computer simulation is proposed. The three-dimensional primary noise source chosen is a transformer noise source. The required simulation algorithm is derived in terms of a deconvolution process.
Acoustic scattering by a sound-hard rectangle
Authors: Boström Anders
Published: October 2005

The scattering of an incoming plane wave by a sound-hard infinitely thin rectangle is considered. An integral equation method which has previously been used for two-dimensional problems [A. Boström, J. Appl. Mech. 84, 503–508 (1987)] and three-dimensional axisymmetric problems [S. Krenk and H. Schmidt, Philos. Trans. R. Soc. London Ser. A 308, 167–198 (1982)] is employed. Starting from a double spatial Fourier field representation, a matching of the conditions in the plane of the rectangle leads to an integral equation for the potential jump across the rectangle. This jump is expanded in a double series of Chebyshev polynomials which fulfill the right edge conditions (but no special measures are taken for the corners where the right conditions are unknown anyway). The integral equation is thus discretized and the problem thereby solved. By a double stationary-phase analysis the farfield is determined and some numerical examples of this are given.
Compressional and shear wave fields in an elastic sphere
Authors: Buckingham Michael J.
Published: October 2005

An exact solution for the longitudinal and transverse wave fields generated by a point monopole source in a solid, elastic sphere in vacuo has been developed. The solution for the scalar and vector potentials is valid throughout the sphere, including the source point. The simple pattern of resonances that would occur in the compressional wave in the absence of shear, vanishes when elasticity is introduced. It is replaced by a much more complicated resonance structure. As a result of coupling at the spherical boundary, the new resonances appear at the same values of the Helmholtz number in the compressional and shear waves. Both fields show a highly structured spatial dependence, in which a predominant feature is radial banding: on tracking out from the center of the sphere to the periphery, the amplitude of the fields alternates in sign. The analytical technique developed for this problem has also been applied to the case of a fluid loaded sphere. This is relevant to sound generation by ice floes in the Arctic Ocean, and to controlled experimental studies of acoustic emission from spherical specimens.
An analysis of the off-axis scattering from solid prolate spheroids
Authors: Hackman Roger H. , Sammelmann Gary S.
Published: October 2005

The acoustic scattering from solid, elastic prolate spheroids is studied as a function of frequency, aspect angle, and aspect ratio. The emphasis of this study is on the prolate spheroid as a transition geometry. The interfocal distance is varied from zero (the spherical limit) to almost unity, as the semimajor axis is held fixed. In this way, the smooth transition from spherical phenomena to what is essentially an infinite cylindrical limit is studied, and the relation between the spherical and infinite cylindrical elastic waves is established. It is argued that the more robust features of the solution for a large aspect ratio spheroid are common to all slender, elongated, axisymmetric solid scatterers of the same aspect ratio, particularly at low frequencies (i.e., low kL/2). It is in this latter sense that the prolate spheroidal solid is expected to be a “generic” large aspect ratio, solid scatterer.
Resonant eigenfrequencies of elastic spheroids and the “level crossing” phenomenon
Authors: Werby M. F. , Castillo J. , Miller Russel , Dickey J. W. , Überall H.
Published: October 2005

The “level crossing” phenomenon, which has been pointed out earlier, is studied here for solid elastic spheroids of varying aspect ratios. Using the NORDA T-matrix code, the frequencies (both fundamentals and overtones) of the resonances are calculated as excited by an end-on incident plane wave. Aspect ratios of the tungsten carbide spheroids range from b/a = 1 (sphere) to 4 in steps of 0.25. The resonance frequencies are expressed in units kb (b = semimajor axis) and correspond to resonating surface waves as they form standing waves around the meridional circumference. While for the resonating Rayleigh waves, the resonance frequencies only rise gradually with increasing aspect ratio, those for the Whispering Gallery waves rise much more rapidly, and, hence, successively cross over the various overtones of the Rayleigh resonances. This phenomenon is explained on the basis of the different character of the dispersion curves (phase velocity versus frequency) for the Rayleigh and the Whispering Gallery waves, as calculated in an exact fashion for a WC sphere and used locally on the spheroids.
Inverse problem and scattering from elastic cylinders at high frequencies
Authors: Quentin G. , Luppé F. , Cand A.
Published: October 2005

For values of k1a larger than 200, it has been previously shown that the echoes backscattered from a cylinder can be explained using a geometrical theory [Quentin et al., J. Acoust. Soc. Am. 70, 870–878 (1981)]. Now the problem of the identification of an elastic cylindrical scatterer from the set of backscattered echoes is addressed. It is shown that from a systematic research, it is possible to deduce the ratio CL/CT of the longitudinal to the transverse velocity in the solid with a very good precision and with less precision for these velocities, the density of the material, and the radius of the cylinder. The advantages of applying to this problem methods deduced from artificial intelligence is also discussed.
A characterization of the power spectrum of scattered ultrasound using a fractal-based analysis
Authors: Kikuchi Tsuneo , Kiryu Shogo , Sato Sojun , Miura Hajime
Published: October 2005

A method for extracting the characteristics of the power spectrum of ultrasound scattered from multiple scatterers using a fractal-based analysis is presented. The shape of the power spectrum is usually very complicated. The shape contains structural information about the medium, because the shape depends on the internal structure of the medium. If the power spectrum of the scattered ultrasound has a fractal structure, characteristics such as self-similarity and fractal dimensions are useful to characterize the power spectrum. When the scatterers are regularly arrayed, a high self-similarity of the power spectrum will be expected. On the other hand, when the array is partially disordered, the sell-similarity of the power spectrum will be lower. Fractal dimensions will be expected to relate to the mean distance between the scatterers. By numerical simulations and basic experiments, the validity of these ideas has been confirmed.
Environmental symmetry breaking: An application of 3-D matched-field processing
Authors: Perkins John S. , Kuperman W. A. , Ingenito F.
Published: October 2005

Self-consistent simulations of matched-field processing in a noisy three-dimensional environment are produced by using the same numerical model for constructing the signal and correlated noise field. In principle, matched-field processing in an asymmetric three-dimensional (range- and azimuthal-dependent) ocean provides the possibility of horizontal beamforming with a purely vertical array since the environment itself breaks the azimuthal symmetry of the vertical array. This scheme is called environmental symmetry breaking (ESB). As a demonstration, an ocean environment is used that has a portion of the Gulf Stream running through the area of interest together with a storm that produces a correlated horizontally (as well as vertically) anisotropic noise field. Linear and nonlinear matched-field processing is considered for a vertical array. These simulations provide the first numerical evidence that ESB can be applied to the underwater detection problem.
A new efficient method of source localization in waveguides processing in mode space
Authors: Shang E. C.
Published: October 2005

Matched-field processing can either be performed in phone space (matching the total field received by each phone) or in mode space (matching the resolved modes). For a stratified waveguide, more efficiency can be obtained in mode space due to the fact that: (1) the source range information and depth information are separable in mode space and the number of replicas is tremendously reduced from (N*M) to (N + M), where N is the range gridding number and M is the depth gridding number, and (2) more confidence can be obtained by making a choice from the resolved modes. In this paper, the “modal feature matching” (MFM) technique has been proposed instead of the “modal beamforming” (MB) technique. One of the advantages of this method is that high performance can be achieved even if only a few modes are available, especially for depth estimation, when two modes are sufficient. Numerical examples are presented.
A joint Dutch research program for developing a high-quality text-to-speech synthesis system
Authors: Pols Louis C. W.
Published: October 2005

Since December 1985, a Dutch national research program has been in operation aimed at the realization of a laboratory prototype system for high-quality, unlimited-text-to-speech synthesis-by-rule for the Dutch language. Four phonetic laboratories (Amsterdam, Leiden, Nijmegen, and Utrecht), plus the Institute for Perception Research IPO in Eindhoven, and the PTT Research Laboratory in Leidschendam work together in this SPIN program. About 12 subtasks are defined ranging from defining the optimal structure of spoken text, grapheme-to-phoneme conversion, and morphological parsing, to studying speaker characteristics, intonation contours, and spectro-temporal speech parameters as a function of stress, speaking rate, and local context. Both allophones and diphones are used as basic units. Formal methods to evaluate the segmental and suprasegmental speech quality are developed and applied during the various phases of realization. In the final 2 years of the project, an optimal system architecture will be developed in order to integrate the single components and in order to achieve an operational implementation. [Work supported by SPIN, the Dutch National Program for the Advancement of Information Technology.]
Cooperative speech technology projects—The Swedish perspective
Authors: Granström Bjöm
Published: October 2005

Speech research has historically held a very strong place in Sweden, especially considering its small population of less than 9 million inhabitants. However, the industrial base for speech technology development is rather small. This is also true for many other countries in Europe. The multitude of small national languages asks for a wide spread of research activities on language specific topics. Cooperation both in research and speech technology product development has recently been started to overcome some of these problems. Sweden, which is still not part of the European Community, has until now been to some extent restricted in that work. The advent of ESCA, the European Speech Communication Association, and the new possibility for noncommunity countries to take part in, e.g., ESPRIT projects mean that Sweden now is taking full part in the growing European cooperation in this area. Some of that work will be described and some cooperative projects between the Nordic countries will be presented. A national Swedish program related to information technology development will also be discussed. This program is financed jointly by The Swedish Board for Technical Development and The Swedish Council for Research in the Humanities and Social Sciences. This acknowledgment of the nature of the subject area will stimulate new formations of cross-disciplinary cooperation.
Overview of speech research in Italy: National and European projects
Authors: Laface Pietro
Published: October 2005

A survey of speech research that is being conducted in Italy, both in academic and in industrial institutions, is presented. Several groups are currently working on speech technology and research in Italy, but no efforts to integrate their activities toward common goals have been so far pursued mostly because no nationwide project has been organized and financed to promote their cooperation. Few commendable exceptions can be listed for which the collaboration between national groups has produced satisfactory results. The support for large-scale man-machine vocal interfaces programs has been granted instead by a number of European projects. Italian groups are participating in these projects in close cooperation with industrial and academic partners of different countries. Among these programs, probably the best known is the ESPRIT project, which is now at the beginning of its second phase. All the aspects of speech and natural language processing have been addressed, from speech analysis and synthesis to speech recognition system assessment; some of the most relevant results will be presented along with some proposals for perspective research. Another European EUREKA project in which Italian groups are involved is PROMETHEUS, an acronym for PROgraM for a European Traffic with Highest Efficiency and Unprecedented Safety, where processing of noisy speech, speaker independence, and dialogue systems are the main topics in the man-machine communication area.
Dynamic characterization of materials: Error analysis of instrumentation and sample mounting configurations versus sample dynamic measurements as a function of material stiffness and form factor
Authors: Collier Robert D. , Laures Jean Philippe
Published: October 2005

The purpose of this investigation is to determine the relative effects of various sample mounting configurations on material measurements for characterization of dynamic modulus and loss factor. Measurements were performed on the Metravib viscoanalyzer over a frequency range up to 1 kHz. The results are compared for samples in both tension-compression and three-point bending configurations. For very soft rubbers, the relative stiffness characteristics of structural mounting and samples limit the range of measurements to below 500 Hz. Loss factors are consistent for both test configurations while dynamic modulus errors for three-point bending are dependent on mounting method and sample form. Optimum test configurations are defined. For various metals and composites, the limits of the two test configurations and optimum sample types and test configurations are determined.
Sensitivity analysis of Polymer Laboratories' dynamic mechanical thermal analyzer
Authors: Deigan R. J. , Dlubac J. J.
Published: October 2005

Polymer Laboratories' dynamic mechanical thermal analyzer (DTMA) measures the dynamic Young's or shear modulus and loss factor of viscoelastic materials. The DMTA infers the modulus and loss factor by measuring the response of a small sample to forced vibrations in a small material sample. An analysis of the parameters affecting the DMTA dynamic modulus and loss factor data is presented. Test results are affected by errors in the input parameters or by violating the assumptions leading to the solution. The extent to which either error affects the test results is quantified. As a result of this analysis, recommended DMTA test procedures are presented.
Geoacoustic scattering from the Pacific seafloor
Authors: Stephen Ralph A.
Published: October 2005

It is amazing how much has been learned about the sediments and igneous crust beneath the sea by invoking the assumption of lateral homogeneity because almost every record obtained of sound propagating through the seafloor contains evidence of lateral heterogeneity and scattering. Three scales of scattering are evident: (1) There is the focusing and scattering of energy due to lateral heterogeneity within the seafloor. This causes anomalously high- or low-amplitude arrivals but no new arrivals; (2) there are diffractions from isolated topographic irregularities such as hills and valleys. In some cases, the hyperbolic appearance of these arrivals is evident on refraction sections; and (3) fine scale heterogeneity in the seafloor causes incoherency and time spread of arrivals. These are ubiquitous effects in seafloor reflections and refractions. These three phenomena will be demonstrated in observed data from the Pacific and in synthetic seismograms.
Seismic profiling at the West Pacific Ocean by DDC1-1 geosonar
Authors: Shuying Zhang , Leifa Ren
Published: October 2005

Some valuable records of seismic profiling at the West Pacific Ocean have been obtained by using DDC1-1 geosonar. A significant discovery is that a layer of sediment, the thickness of which is more than 500 m, exists at the area of Ryn-Kyn Ocean Trench, where the water depth is over 6700 m. The DDC1-1 geosonar consists mainly of a 30 000-J sparker as a strong wideband sound source and a 50-m-long streamer, including 20 equally separated hydrophones and an echo-processing system. Several new techniques have been developed for the improvement of both penetration and resolution of seismic profiling, such as: (1) time-varying filtering—the frequency band of the sonar receiver can be varied in real time with the variation of the echo travel time according to an adjustable pattern depending on the acoustic attenuation of marine sediments; and (2) synthetic-aperture processing—an exponential accumulator is used for stacking a series of echoes from some certain subsurfaces of sediments in real time corresponding to successive shots of the sound source. The gain of echo to interference ratio by means of this technique is determined by G = 10 log [(2N − 1) 1 − (1 − 1/N)p1 + (1 − 1/N)p] dB, where p is the stacking time and N is an adjustable parameter that determines the maximal gain of the accumulation processing.
Project SWATHMAP: Military sonars in service to science
Authors: Humphrey Peter B.
Published: October 2005

Project SWATHMAP (one of four deep-water, long-range sidescan sonars in operation today) is the low-cost geologic application of a U. S. Navy antisubmarine warfare system utilized on routine ocean-wide deployments. While resolution is not sufficient to observe bathymetric structures in detail, the system is particularly adept at locating them, discerning scale and shape, and determining continuity. Routine observations include terraces, trench crossings, seamounts (many of them newly discovered) often topped by craters, fracture zones, and abyssal hills (both superb clues to plate tectonic motion). Discoveries on this scale are essential for ground truthing the next decade's satellite altimeters. Certainly there are sidescan systems that do a better job of seafloor mapping than American combat vessels, but their cost is extraordinary by comparison and well beyond the reach of most nations. By contrast, even the humblest antisubmarine warfare-equipped navy can use such a system to locate most substantial features within its exclusive economic zone. Possible system upgrades include (1) two-sided scanning for maximum coverage, (2) stereo image production from parallel passes or sequential imaging, (3) digital tape recording for subsequent image manipulation and enhancement, and (4) decipherment of parallax across the array to determine the acoustic arrival angles one utilizes to estimate bathymetry.
Simultaneous sensing of the acoustic wave and temperature using a polarization-maintaining fiber
Authors: Takahashi Sumio , Kikuchi Toshiaki , Yagi Ryohei , Hasegawa Akio
Published: October 2005

Many types of fiber-optic sensors have been proposed and developed. In general, efforts have been made to detect a specific parameter of interest separately from other parameters. In the homodyne interferometric type of sensors, the fading of output caused by temperature variation is a serious problem, and several types of compensation schemes have been developed. In contrast, this paper describes the simultaneous sensing of acoustic wave and temperature change using a polarization-maintaining fiber. The acoustic wave is detected by an optical heterodyne scheme and temperature change is detected by an optical homodyne scheme. The zeroth-order diffracted light from a Bragg cell is directed into both the X and Y polarization axes of a polarization-maintaining fiber. The homodyne interference of the X and Y components is utilized to detect the temperature variation. At the same time, the heterodyne interference of the X polarization component of the output light from the fiber and the first-order diffracted light propagated in air is used to detect the acoustic wave. Simultaneous sensing of the acoustic wave and temperature variation was successfully demonstrated by this method.
Elastic wave propagation in multilayered anisotropic media with applications to fibrous composites
Authors: Nayfeh Adnan H. , Chimenti Dale E.
Published: October 2005

Theoretical analysis supported by extensive experimental investigations for the propagation of elastic waves in multilayered anisotropic media is presented. Each component of the solid is allowed to possess up to monoclinic symmetry properties. Furthermore, the wave is allowed to propagate along any azimuthal direction. Both free and forced waves are considered. Waves incident from within a supporting fluid on the fluid-multilayered medium interface are given special attention. Here, the reflection and transmission coefficients are derived from which all propagation characteristics are identified and are readily available. The analytical results are exact and hence cover all frequency ranges. Experiments are conducted on a multilayered fibrous composite plate of graphite epoxy lamina. Results are presented in the forms of comparisons of theory and experiments for dispersion characteristics. Also, comparisons of reflected energy distribution as a function of frequency times thickness are included.
The collection efficiency of an electrostatic precipitator with ultrasonic application
Authors: Nakane Tomoo , Seya Koichiro
Published: October 2005

An electrostatic precipitator (ESP) has a lower collection efficiency for smaller particles. It is believed that increasing the submicron particles sufficiently for the operation of ESP would lead to a good collection efficiency. A high-intensity ultrasonic field was produced inside an ESP, and the collection efficiency was examined, and, as a result, a higher collection efficiency was obtained with the application of ultrasonic agglomeration. The collection efficiency obtained was higher than previous reports. The experimental ESP was of the pipe type and sample particles were made by diluted burning incense sticks in this experiment. Sound waves were produced by a stepped circular vibrating plate at a frequency of 20 kHz.
Visual observation of electrical discharges in a standing sound wave field
Authors: Hirata Takashi , Seya Koichiro
Published: October 2005

There are many papers reporting the effects of electrical discharge, such as in atmospheric pressure, gaseous mediums, and the shape and geometry of an electrode. However, in spite of the fact that an electrical discharge phenomenon accompanies sound waves, there are very few reports regarding the influence of sound waves on the discharge phenomenon. In this paper, it is visually confirmed that discharging phenomena are influenced by sound waves irradiating the electrical discharge. Discharging cells with both positive and negative needle electrodes were located at a sound-pressure node in a standing wave field. As a result, the luminous part of the electrical discharge changed to a leaflike shape, and the starting voltage of the discharge also changed.
Measurements of the acoustic characteristics of newly developed plastics
Authors: Gakumazawa Masahide , Kaneko Seiji , Ueha Sadayuki
Published: October 2005

Newly developed plastics, including FRP, which are called engineering plastics, have been widely used in place of metals and are often welded together or machined by means of ultrasonic vibrations. However, their acoustic characteristics have been hardly reported, except for their physical properties. The attenuation constants and velocities of such plastics have been measured by using a simple pulse-echo method. The frequencies used were 0.5, 1.0, 2.0, and 5.0 MHz. The frequency dependence of the attenuation was measured for several kinds of plastics. The attenuation of engineering plastics was shown to be larger than that of conventional plastics.
A method for ultrasonic manual testing and classification of test results for welds of ferritic steel with acoustic anisotropy
Authors: Yamaguchi Hisao
Published: October 2005

Angle-beam ultrasonic testing has been applied to flaw detection in steel welds according to specifications based on the isotropy of the steel. However, certain types of rolled steel plates show an anisotropy that arises during the rolling processes necessary to satisfy the required mechanical qualities. In the angle-beam ultrasonic testing of steel with some degree of anisotropy, a change in the refraction angle and a decrease in the echo amplitude are observed. Considering this fact, the Japanese Society for Nondestructive Inspection has made a new standard for the angle-beam ultrasonic testing of welds of steel plates with anisotropy over 1.02 in shear wave velocity ratio. The following items are specified in the standard, which is mainly applied to welds of ocean structures and ships: (1) It is recommended that probes of a 60- or 65-deg nominal refraction angle be used. (2) The estimation of the flaw location should be made by using the refraction angle measured in the test steel. (3) The sensitivity should be adjusted using reference blocks with side drilled holes.