bluuebunny/crossref_metadata_2025 huggingface dataset:
Detection of strain-induced wavelength shifts in an optical fiber Bragg grating using an over-coupled coupler
Authors: Zhang Q. , Brown D. A. , Kung H. , Townsend J. , Reinhart L. , Morse T. F.
Published: October 2005

A highly over-coupled fused biconical tapered fiber coupler has been used to interrogate the strain-induced wavelength shifts from an optical fiber Bragg grating. Both the 95% reflective fiber gratings and the over-coupled couplers were fabricated in our laboratory. The coupler has a spectral period of approximately 4 nm at the optical interrogation wavelength of 1550 nm. The outputs are processed using a software-based demodulator programmed in Labview. Results of static and dynamic induced strains and sensor prototypes will be presented. [Work supported in part by NPS and NSF.]
The cocktail party effect in infants
Authors: Jusczyk Peter W. , Newman Rochelle
Published: October 2005

Most research on speech recognition by infants occurs in quiet laboratory rooms with no outside distractions. But the real world may not resemble the laboratory: Much speech directed to infants occurs with competing acoustic signals. To learn language, infants need to follow their care-givers’ speech even under less than ideal listening conditions. Infants’ abilities to follow a female speaker’s voice when a male voice was talking simultaneously were examined. In pilot studies, infants presented with two competing streams of fluent speech showed no evidence of recognizing words spoken by the target voice. In the present study, infants heard a target voice repeating isolated words, while the second voice spoke fluently at either of three different loudness levels. Subsequently, infants heard passages produced by the target voice using either the familiar words, or novel words. Infants listened longer to the familiar words when the target voice was 10 or 5 dB louder, but not when the distractor was equally loud. This suggests that infants could separate the two voices, provided the target voice was at least 5 dB louder. Hence, infants have some capacity to extract information from speech even in the face of competing acoustic signals. [Work supported by NICHD to PWJ and an NSF Graduate Fellowship to RN.]
Ray identification theory in ocean acoustic tomography
Authors: Mauuary D.
Published: October 2005

The identification problem in multipath ocean acoustic tomography is not only one of the more crucial but also one of the more difficult signal processing problems to solve for further inverse studies. It is only recently that a tool, based on the Bayesian decision theory and close to the data association problem in RADAR, has been proposed by Mauuary and Moura. It fundamentally uses prior information ocean variability which transits through the ray acoustic model. It also statistically solves the ray identification problem with a Bayesian strategy. Despite the inherent complexity of resulting algorithms, a first successful attempt has been made on a French tomographic set of data (GASTOM). Some simplifications and further experimental use are now being investigated on the Mediteranean set of data (THETIS). With another approach given by Send, those are the only practical tools, but, they are sufficiently general to solve the identification problem in the most difficult conditions given by unresolved and unstable data. Both solutions are very close to the generalized Kalman filter theory and joint use of these algorithms in data assimilation models can be expected.
Estimation of the elastic stiffness coefficient c13 of fixed tendon and fixed myocardium
Authors: Hoffmeister Brent K. , Handley Scott M. , Verdonk Edward D. , Wickline Samuel A. , Miller James G.
Published: October 2005

Recent studies from our laboratory have detailed the anisotropy of velocity of quasilongitudinal-mode ultrasonic waves through formalin fixed samples of normal human myocardium and bovine Achilles tendon. Results of these studies were used to determine the elastic stiffness coefficients c33, corresponding to the propagation of longitudinal-mode waves parallel to the fiber axis of the tissue, and c11, corresponding to the propagation of longitudinal-mode waves perpendicular to the fiber axis. For a tissue possessing a unidirectional arrangement of fibers with a random transverse distribution, three additional coefficients, c13, c44, and c12, are needed to describe its linear mechanical properties completely. Direct ultrasonic measurements of these coefficients in solids typically require the propagation of transverse-mode waves through the sample. Such measurements are difficult to perform in soft tissues because transverse-mode ultrasonic waves are very highly attenuated by the tissue. This study therefore employs a technique to estimate c13 based on measurements of the velocity of quasilongitudinal-mode ultrasonic waves for numerous angles of propagation relative to the fiber axis of the tissue. Analysis of data obtained from formalin fixed bovine Achilles tendon and human myocardium yield estimated values for c13 of 3.17 and 2.46 GPa, respectively.
The inverse problem for scattering by an ellipsoidal boss
Authors: Lucas R. J.
Published: October 2005

The inverse problem of determining the semiaxes and orientation of an ellipsoidal boss on a base plane is considered. For low-frequency plane-wave excitation of a rigid surface, it is shown that four measurements of the leading order coefficient of the imaginary part of the scattering amplitude are sufficient to specify the boss. At high frequencies, a measurement of the time of flight of the backscattered wave together with geometrical considerations is used to construct a supporting plane at the point of specular reflection on the boss. Knowledge of four such planes corresponding to four directions of incidence is then used to solve the inverse problem. The method applies for both rigid and acoustically soft surfaces. For either excitation, a priori knowledge of the boss, e.g., its orientation, reduces the number of required measurements.
Formant frequency values of vowels produced by preadolescent boys and girls
Authors: Busby P. A. , Plant G. L.
Published: October 2005

The fundamental frequency (F0) and the first three formant frequency (F1, F2, and F3) values of vowels produced by 40 preadolescents were measured. There were five boys and five girls in each of four age groups: 5, 7, 9, and 11 years old. The 11 nondiphthong vowels of Australian English which can be produced in a stressed syllable were used. The F0 values decreased with increases in age, but there was no difference between boys and girls. In general, the F1, F2, and F3 values decreased with increases in age, and the values for girls were higher than those for boys.
On the viscoelasticity of the polyurethane foam
Authors: Sfaoui A.
Published: October 2005

In this paper a method is presented that allows the characterization of Young’s modulus behavior of the polyurethane foam frame. This parameter has been evaluated according to a technique based on the measurement of the dynamic mass of a cylindrical sample in a rough vacuum. In the approximate temperature range 20 to −15 °C the Young’s modulus has been measured over the approximate frequency range of 102 Hz–2 kHz. The effect of the temperature on the dynamic mass components, principally on its imaginary part has led to the use of the Williams-Landel-Ferry (WLF) theory to describe the Young’s modulus behavior over a wide range of frequencies.
Atmospheric absorption of sound: Further developments
Authors: Bass H. E. , Sutherland L. C. , Zuckerwar A. J. , Blackstock D. T. , Hester D. M.
Published: October 2005

This Letter is an extension of an earlier Letter by Bass et al., ‘‘Atmospheric absorption of sound: Update’’ [J. Acoust. Soc. Am. 88, 2019–2021 (1990)]. Errors in a formula for saturation vapor pressure are corrected, and an alternative, much simpler formula is given. The role of atmospheric pressure is emphasized by giving formulas in which the absorption, frequency, and relative humidity are all scaled with respect to atmospheric pressure. Also presented are new, more readable and useful figures showing atmospheric absorption as a function of frequency, relative humidity, and atmospheric pressure. The new figures make it possible to estimate accurately the absorption at any value of atmospheric pressure.
The impact of the background bubble layer on reverberation-derived scattering strengths in the low to moderate frequency range
Authors: Keiffer Richard S. , Novarini Jorge C. , Norton Guy V.
Published: October 2005

The impact that a near-surface, range-independent background or persistent bubble layer may have on the derivation of sea surface backscattering strengths from reverberation measurements is examined. A simple ray model is proposed to account for the refractive and attenuating effects of the bubble layer and is used to calculate the modified insonification of the air–sea interface. This simple approach is validated against a highly accurate numerical solution. Scattering at the interface is handled via first order small perturbation theory. The combined propagation/scattering model is exercised in the low- to moderate-frequency range in order to examine bubble-induced modifications to sea surface backscatter calculations. Results indicate that the refractive effects due to the background bubble layer significantly enhance scattering levels as a function of wind speed. Furthermore, reasonable variations in the background bubble spectrum are shown to yield scattering levels that compare quite well with explosive source data from the 7th Critical Sea Test (CST-7) and the Chapman–Harris experiment. The model also predicts a weaker grazing angle and frequency dependence than evidenced in either data set.
Supersonic acoustic intensity
Authors: Williams Earl G.
Published: October 2005

A new acoustic quantity called the supersonic acoustic intensity vector is defined in this paper for application to measurements on plate and cylinderlike structures. As the name implies, the supersonic intensity is composed only of wave components which radiate to the far field (supersonic), with the nonradiating (subsonic) components eliminated. The normal component of this vector, measured in the extreme near field or on the surface of the structure, provides an accurate tool for locating regions (‘‘hot spots’’) on the structure which radiate to the farfield. Furthermore, the supersonic intensity provides an accurate quantification of these source regions, providing a ranking of the strength of the identified source regions as a function of frequency. This identification and ranking provides a powerful new tool in the understanding and control of radiated noise.
Is intra-articulator speech coarticulation planned?
Authors: Ostry David J. , Gracco Vincent L.
Published: October 2005

Does the nervous system take account of upcoming phonetic context when planning successive movements of a speech articulator? The kinematics of intra-articulator coarticulation are readily measurable in empirical studies and may appear to be centrally controlled on the basis of kinematic changes which arise in response to upcoming phonetic segments. However, without explicit models of speech articulators, measured kinematic effects correctly attributable to central planning cannot be distinguished from the kinematic patterns which are due to dynamics and are not represented in the underlying control. In the present paper, this question is addressed by comparing the results of empirical and modeling studies of jaw motion. The simulated kinematics of sagittal plane jaw rotation and horizontal jaw translation are compared to empirical studies in which subjects produce CVC sequences at a normal rate and volume. The jaw motion simulations show that even when control signals underlying the initial CV transition are fixed, ‘‘anticipatory’’ kinematic patterns vary in amplitude and duration as a function of upcoming context. This suggests that unplanned effects due to articulator dynamics must be accounted for before drawing conclusions about the role of central control in intra-articulator coarticulation. [Work supported by NIH Grant CD-00594.]
Environmental vibrations associated with high-speed trains
Authors: Krylov Victor V.
Published: October 2005

The dramatic revival of railways in Europe to become one of the most advanced and fast developing branches of transportation technology may be compared with the space technology breakthrough of the 1960s. The reason is high speeds achievable by the most advanced modern railway trains, e.g., French TGV trains for which a maximum speed of more than 515 km/h was recorded in May 1990. Unfortunately, the increased speed of railway communications is likely to raise levels of associated environmental noise and vibration far beyond those significant even for conventional railways. A review is given of recent progress in the theoretical investigation of ground vibrations generated by high-speed railway traffic, with emphasis on problems associated with superfast trains, i.e., trains traveling at speeds close to or greater than 300 km/h. Significant increase in ground vibration levels (more than 70 dB) is predicted for superfast trains if they travel at speeds higher than Rayleigh wave velocity in the ground [V. V. Krylov, J. Phys. IV, C5 4, 769–772 (1994)]. Attention is paid to establishing relations between parameters of the problem, e.g., geometrical dimensions of track and train, layered structure of the ground, train speed, etc., that could result in direct reduction in ground vibration generation efficiency.
Cortical codes for sound location
Authors: Middlebrooks John C. , Clock Eddins Ann , Xu Li , Green David M.
Published: October 2005

The responses of auditory cortical neurons carry information both in the number of spikes within a burst and in the timing of those spikes. The capacity of single neurons to encode sound locations was studied in areas A1 and AES of α-chloralose-anesthetized cats. The spike counts of about half of studied neurons were modulated by more than 50% as a noise source was varied in azimuth. Nevertheless, the ‘‘best areas’’ of most units, using a 50%-of-maximum-response criterion, were larger than 180°. Temporal spike patterns of single neurons could be classified according to sound source azimuth, using an artificial neuron network. The classification of temporal patterns consistently surpassed a maximum-likelihood classification of spike counts. The spike patterns of single neurons could successfully encode locations throughout 360° of azimuth. The localization performance of any single neuron was substantially worse than that of an awake, behaving cat. When responses were averaged across multiple trials, however, performance improved monotonically with increases in the number of trials, suggesting that the information carried out by the temporal spike patterns of multiple neurons could account for a cat’s localization behavior.
Importance of tonal envelope cues in Chinese speech recognition
Authors: Fu Qian-Jie , Zeng Fan-Gang , Shannon Robert V. , Soli Sigfrid D.
Published: October 2005

Temporal waveform envelope cues provide significant information for English speech recognition, and, when combined with lip reading, could produce near-perfect consonant identification performance [Van Tasell etal., 1152–1161 (1987)]. Tonal patterns are important for Chinese speech recognition and can be effectively conveyed by temporal envelope cues [D. H. Whalen and Y. Xu, Phonetics 49, 25–47 (1992)]. This study investigates whether tones can help Chinese-speaking listeners use envelope cues more effectively than English listeners. The speech envelope was extracted from broad frequency bands and used to modulate a noise of the same bandwidth. Mandarin vowels, consonants, tones, and sentences were identified by ten native Chinese-speaking listeners with 1, 2, 3, and 4 noise bands (or channels). The results showed that recognition of vowels, consonants and sentences increases dramatically with the number of channels, a pattern similar to that observed in English speech recognition. However, tones were consistently recognized at about 80% correct level independent of the number of channels. This high level of tone recognition produced a significant difference in open-set sentence recognition between Chinese (11%) and English (1%, p<0.01) for the one channel condition where no spectral information is available.
Nonlinear waves through multicomponent fluid media with chemical reactions
Authors: Margulies Timothy S.
Published: October 2005

Finite-amplitude wave propagation has been investigated using balance and constitutive equations derived via continuum mixture theory for a multicomponent system such that simultaneous chemical reactions can occur. A multiple-time scale perturbation approach [T. Tanuiti and C.-C. Wei, J. Phys. Soc. Jpn. 24 (4), 941 (1968)] was used to develop a differential-integral equation for nonlinear wave propagation when diffusive motions can be neglected. The processes of dissipation (e.g., viscous and thermal), chemical relaxation, and nonlinear equation of state response influence the wave profile. Approximations, such as low-frequency and high-frequency expansions [J. Engelbrecht, Wave Motion 1, 65 (1979)] are examined. The low-frequency results in the classical Burgers’ equation. Applications with calculations use information available in the literature for ocean and electrolytic solution environments. The case of slightly inhomogeneous media will also be discussed.
Vibration and sound radiation of Mindlin plates including in-plane motion, stiffened by thin walled beams
Authors: Locqueteau C. , Berry A.
Published: October 2005

Stiffened panels such as those encountered in marine structures may exhibit in-plane motion in the panel due to the coupling with the deformation of the stiffeners. Most of the published papers on Mindlin stiffened plates do not take into account the in-plane motion of the panel. This paper presents a vibroacoustic model of finite, stiffened panel including flexion, shear, and in-plane motion of the panel, and flexion, torsion, and warping of the thin-walled beam stiffeners. The vibration problem is solved through a Rayleigh–Ritz approach, both for the fluid-coupled and the uncoupled cases. The numerical results are compared to recently published data. The effects of shear deformation and in-plane deformation of the panel are systematically investigated in terms of the panel response and sound radiation, and the results are compared to a simpler model retaining only pure flexural deformation of the panel and stiffeners. [Work supported by Defense Research Establishment Atlantic, Contract OSC92-01908.]
Investigation of accuracy of sound-speed measurements in solids: A novel method
Authors: Proctor Thomas M.
Published: October 2005

Speed of sound in solids has been measured by a number of different techniques over the past 5 decades. Unfortunately, consistent repeatability and accuracy have been a rare occurrence. Many error-producing problems of a fundamental nature have kept this experimental finding suspect at best. In liquids, the definition, dl/dt, for speed of sound can be used to check the accuracy of the method but, for solids, such incremental changes in path length are not possible. In the case of a plate, a combination of modifications to the procedure for the normal on-axis-plane wave experiment are possible. Over the past 15 years, a number of improvements and innovations have enhanced the field of acoustic emission. The development of a point contact receiving transducer and a repetitive impulsive point source in conjunction with developed Green’s function theory for the plate geometry have allowed for a new way of doing the ultrasonic velocity measurement. This new approach will be discussed and error problems inherent in this technique will be examined. Results of change in length versus change in time of flight will be analyzed. [Work performed by contract to NIST.]
Interrelationships between ethanol intoxication and speech
Authors: Hollien Harry , Martin Camilo A.
Published: October 2005

The focus of this paper is on (1) establishing well-controlled procedures which will permit reasonably precise study of the effects of intoxication on speech and (2) assessing correlations between physiological and behavioral measures of intoxication. In the first instance, selection and exclusionary criteria will be discussed and their impact on the resulting experiments noted. Included will be (1) subject selection (familial history, background, health, gender, drug/medication status, drinking patterns), (2) dosage protocols (control over and monitoring of intoxication, modifications), and (3) procedural constraints (speech tasks, experimental controls). Some of the criteria and procedures employed proved satisfactory, others did not and had to be modified. Second, two aural-perceptual experiments (eight talkers, 106 auditors) will be reported; a scaling model was used in the first, three variations of a blind sort procedure in the second. Two patterns of subject behavior were found; one correlated well with the physiological measures of intoxication but the other did not. Moreover, the differences in the speech shifts did not appear directly related to subjects’ drinking patterns. [Research supported by NIH.]
Probability theory and speech perception
Authors: Boothroyd Arthur
Published: October 2005

Fletcher recognized the value of probability theory in developing a quantitative approach to speech perception—hence the articulation index (AI). He also recognized the need to allow for violations of the independence assumptions that underly basic probability theory. For example, in nonsense syllables, the probability (pw) of recognizing a word equals pnp, where pp is the probability of recognizing the constituent phonemes and n is the number of phonemes per word. In real words, however, pw=pjp, where n≥j≥1. Similarly, extending the methods of AI, the probability of recognition of words in sentences (spw) can be shown to be related to the probability of recognition in isolation (ipw) by the equation spw=1−(1−ipw)k, where k is an exponent reflecting the contribution of the sentence context. From these two basic equations one can derive relationships among many measures of speech perception, ranging from the phonetic level to the sentence level. The empirical values of the exponents j and k can be used both to quantify the effects of various structural and contextual constraints and to assess an individual’s use of those constraints. [Work supported by NIDCD Grant No. 10078.]
Seismoacoustic observations as related to thermally induced stresses and fracturing in pack ice
Authors: Lewis James K.
Published: October 2005

On-ice geophone data and under-ice noise data contain a significant amount of information about the stress state of pack ice and how ice fractures in response to the stress. This information can be used to study the rheology of sea ice and the related mechanics of fracturing. A review is presented of the current understanding of ice mechanics related to thermal fracturing based on seismoacoustic observations. A rheology is presented and discussed based on a thermodynamic model and an associated stress/strain relationship. The rheology has an enhancement which prescribes how the extent of existing cracks in the ice affect (1) the stress state of the ice, (2) the number of fractures when the ice exceeds its yield strength, and (3) the stress relief after fracturing occurs. This allows us to simulate first-year and multiyear ice using the same model by differentiating the two ice types based on the extent of existing cracks. Examples are shown of how under-ice acoustic data can be used to estimate the vertical distribution of the fractional area of existing cracks in multiyear ice.
Determination of categories of acoustical quality in concert halls using the questionnaire and interview method
Authors: Beranek Leo L.
Published: October 2005

There are three common alternative techniques for judging subjective acoustical quality in concert halls and opera houses: (1) the binaural comparison method; (2) the expert-group round-robin listening method; and (3) the questionnaire and interview method. The questionnaire and interview method was utilized by me in rank-ordering 55 concert halls in 22 countries. Conductors, musicians, and music critics were interviewed and each was asked to rank-order the halls he/she knew well. In addition, to cover all halls, opinions were solicited from those who listen often to symphonic music in many halls, which included acoustical consultants and selected listeners who travel extensively and attend symphonic concerts. I have attended symphonic concerts in all but six. The halls were then separated into six categories from A+(super), A(excellent), B+(good to excellent), B(good), C+(fair to good), and C(fair). No rank-orderings were attempted within each category. It is probable that some halls might be ranked one category higher or one category lower than its present assignment if a different group if interviewees were selected. A shift of two categories is highly unlikely. The results for the 55 concert halls are presented and discussed.
Evaluating acoustical qualities of four rooms using questionnaires
Authors: Siebein Gary W. , Gold Martin A. , Spolan Mitchell , Herr Christopher
Published: October 2005

A large group of students listened to anechoic recordings of music and speech samples at several locations in four different performance rooms: a large 2000-seat multipurpose performing arts center; a black box theater; a 250-seat lecture hall; and an open field. A brief piece by Mozart played by a string quartet, a portion of a symphony by Bruckner, a soliloquy from Hamlet, and standard speech intelligibility word lists were played through a single loudspeaker located at the center front of the performing area of the room. Students evaluated qualities of sound including clarity, intimacy, envelopment, balance, reverberance, loudness, and overall impression on a bi-polar semantic rating scale. They also took speech intelligibility tests. The overall impression of the pieces of music in the black box theater and the lecture hall were scored higher than the other two rooms. There were significant differences in the ratings of the different musical pieces in all rooms. The ratings in the outdoor tests were consistently less than those in all of the indoor locations by over two scale points illustrating the importance of room effects. The ratings in the performing arts center for the recorded music were significantly lower than ratings obtained at the same locations by a group of students evaluating live orchestral performances in the room. [Work supported by NSF.]
Wavelet applications to bottom sediment classification
Authors: Priebe Russell , Chotiros Nicholas P. , Walter Donald J. , Lambert Douglas N.
Published: October 2005

Wavelet signal decomposition techniques applied to fathometer echoes were used for seafloor classification. Fathometer echoes were deconvolved with their source signals to yield transfer functions representative of the seafloor. These transfer functions were then expanded onto damped complex exponential wavelet bases. In this case a discrete implementation of the continuous wavelet transform was used. This technique allowed the signals be decomposed into distinct modes by localizing signal component energies in time and frequency. Modal features were then analyzed for clues to the physical makeup of the seafloor. Techniques were developed for extracting modal features from the wavelet signal expansions. These modal features include modal densities, center frequencies, bandwidths, duration, and most importantly, decay rates. The modal features were analyzed for clues to the physical makeup of the sea bottom. Available information was exploited to invert for internal sediment structure, particularly sediment density and the presence of trapped bubbles. Feature-based bottom maps were generated allowing classification of the seafloor. [Work supported by NRL/SSC under the MTEDS program.]
Combined volume and surface scattering in a channel using a modal formulation
Authors: Frankenthal Shimshon , Beran M. J.
Published: October 2005

In previous work, a modal approach was used to study random volume scattering in a shallow channel [M. J. Beran and S. Frankenthal, 3203–3211 (1992)]. Here, the way to include the effects of a rough channel surface in the formulation is shown. To include the effects of a rough surface, the modes are taken to be dependent on the range and transverse coordinates in addition to the depth coordinate. The propagation is studied in terms of the ensemble-averaged two-point coherence function and the equation governing the coherence function is derived. In order to insure energy conservation when the generalized modal field equations are simplified, the parabolic approximation is replaced by a method which includes both forward and backward propagating fields. The two-point coherence function is expressed as the sum over both self-modal and cross-modal coherence functions. The difference between the equations governing the self-modal coherence functions and the cross-modal coherence functions is considered. A numerical example which uses typical shallow water parameters is presented. Figures portray how the mode energies are transferred between the modes as the acoustical field propagates. [This work was partially supported by ONR.]
Adaptive wavelet collocation methods and wave propagation
Authors: Cai Wei
Published: October 2005

An adaptive wavelet collocation method for the initial value boundary problem of nonlinear PDE’s is studied. The collocation method is based on a cubic spline wavelet decomposition for the Sobolev space H20(I), where I is a bounded interval. Based on a special ‘‘point-wise orthogonality’’ of the wavelet basis functions, a fast discrete wavelet transform (DWT) is constructed. This DWT transform will map discrete samples of a function to its wavelet expansion coefficients in O(N log N) operations. The issue of efficient data structure for the wavelet collocation methods will also be discussed. Numerical results for various PDE’s including wave propagation will be presented.
Near-field acoustic solution of a rotating point source in frequency domain
Authors: Ju Hongbin , Sheng Menyu , Zhong Fangyuan
Published: October 2005

To do research on the aeroacoustic mechanism of turbomachinery or any other rotating machines, it is important to study the acoustic characteristics of the rotating sources. Based on the frequency domain solution of moving sound sources, an approximate acoustic solution of a rotating point source in the near field, which is the superposition of a far-field solution and three near-field modification items, is given if the rotating radius is acoustical compact when compared with the field sound wavelength. Accordingly, the near-field Green’s function in free space is obtained. Then, the directionality characteristics of the sound field induced by rotation is discussed, and the influence of source position, source frequency, and rotating frequency is studied in detail. The results reveal that the distribution of near-field modifications is discrete around the viewing angle, and the influence on near-field modification by the rotating radius happens mostly around the rotating plane, while the influence of the axial position of the source happens mostly near the rotating axis.
Tomographic inversion of fish parameters in shallow water
Authors: Diachok Orest
Published: October 2005

Simulations of Weston’s measurements of the temporal variability of anomalously large attenuation due to fish, suggest the possibility of tomographic inversion of pelagic fish parameters over large spatial dimensions (nominally 50 km radius) in shallow water. These measurements reveal resonances which are a function of fish bladder size and depth. Computations suggest that the latter may be inferred from modal attenuation measurements [Diachok, European Conference on Underwater Acoustics (1994)], hypothetically permitting unambiguous estimation of bladder size. In the horizontal dimension pelagic fish concentrate into ‘‘clusters’’ of schools at scales, which are driven by the ‘‘patchiness’’ of plankton, which in turn is hypothetically controlled by atmospheric and bottom conditions, and by oceanic mesoscale phenomena such as eddies, fronts, and upwelling events. A fixed, large-scale tomographic array consisting of several widely spaced transmitters and receivers, designed to invert ocean parameters at low frequencies and fish parameters over a broad range of higher frequencies, together with quasisynoptic measurements of plankton parameters (probably from ships), would permit investigation of fish adaptation(s) to the temporally evolving mesoscale environment. Criteria for the design of such a bioacoustic observatory, and its advantages and disadvantages compared to shipborne methods and fixed long-range active monitoring, will be discussed.
Measurement of the distortion level of a loudspeaker using an adaptive filter algorithm in a reverberation and noisy environment
Authors: Kim Chun-Duck , Jee Suk-Kun , Masato Abe
Published: October 2005

This paper describes a method to measure the distortion level of a loudspeaker and an amplifier using a LMS (least-mean square) adaptive filter. The acoustic apparatus checks the distortion level and the residual noise using a bandpass filter having a sharp cut-off frequency characteristic and a sinusoidal oscillator. The above bandpass filter, however, is expensive and has a long response characteristic. It is impossible to check each harmonic distortion. Also, to check the harmonic distortion of a loudspeaker in a room with ambient noise, the experiment room needs to be an anechoic chamber. On the other hand, the proposed method offers an easy way to measure the specified harmonic distortion level with a small amount of hardware. Moreover, this method is not affected by ambient noise which has no correlation with the test signal. The measurement can be carried out in a noisy environment. The system consists of a 32-bit DSP96002, 2ch of 16-bit analog to digital converter, and a 5th Chebyshev filter with a 50 kHz sampling frequency. The effective of the proposed method confirmed by experiments using a loudspeaker carried out in a room with ambient noise.
Effects of syllable duration on syllable-final stop-glide perception by humans and monkeys
Authors: Sinnott Joan M. , Borneman Melissa A. , Dagenais Paul A.
Published: October 2005

Humans and monkeys were compared in their perception of phoneme boundary shifts along two synthetic syllable–final stop–glide /bopen ayeb/–bopen ayeU/ continua differing in overall syllable duration (150 vs 320 ms). Humans were first tested with a written identification procedure and showed a boundary shift to longer transition durations with increased syllable duration, as previously reported in the literature for syllable–initial stop–glide /bopen aye–wopen aye/ data. Humans and monkeys were then tested with a low-uncertainty discrimination procedure but showed little evidence of a sensory-level discontinuity underlying the identified boundaries: Instead sensitivity appeared to follow Weber’s law. Finally, both human and monkeys were tested with a go/no-go identification procedure specifically designed for monkeys. Both species clearly showed the shift effect, but quantitative differences emerged between the species that were generally consistent with comparative psychoacoustic measures of temporal discrimination. [Work supported by NIDCD.]
Acoustic thermometry of ocean climate (ATOC)
Authors: Munk Walter H.
Published: October 2005

The rocky road followed in the 1990s leading to the present status of acoustic thermometry of ocean climate (ATOC) will be reviewed.
Internal wave effects on long-range ocean acoustic tomography
Authors: Wolfson M. A. , Spiesberger J. L. , Tappert F. D.
Published: October 2005

Full-wave numerical simulations of internal wave scattering of low-frequency sound in the deep ocean are performed with an efficient broadband PE model based on a new parabolic approximation that is second-order accurate, and an internal wave model based on a new representation of the GM spectrum that allows efficient generation of internal wave fields that evolve in geophysical time. Results are displayed as plots of acoustic travel time versus geotime for various source–receiver separations (up to 8 Mm), and various center frequencies and bandwidths. Quantitative examination (coherent and incoherent geotime averages) yields information about the temporal coherence and stability of each multipath. It is found that the later near-axial arrivals are unstable and unresolvable, and therefore not useful for tomography, at ranges and frequencies that are consistent with the predictions of Dozier and Tappert [ 533–547 (1978)] who used a coupled mode model. [Work supported by ONR and ARPA.]
Factors affecting strength of perceived foreign accent in a second language
Authors: Flege James Emil , Munro Murray J. , MacKay Ian R. A.
Published: October 2005

This study assessed the relation between non-native subjects’ age of learning (AOL) English and the overall degree of perceived foreign accent in their production of English sentences. The 240 native Italian (NI) subjects examined had begun learning English in Canada between the ages of 2 and 23 yr, and had lived in Canada for an average of 32 yr. Native English-speaking listeners used a continuous scale to rate sentences spoken by the NI subjects and by subjects in a native English comparison group. Estimates of the AOL of onset of foreign accents varied across the ten listeners who rated the sentences, ranging from 3.1 to 11.6 yr (M=7.4). Foreign accents were evident in sentences spoken by many NI subjects who had begun learning English long before what is traditionally considered to be the end of a critical period. Very few NI subjects who began learning English after the age of 15 yr received ratings that fell within the native English range. Principal components analyses of the NI subjects’ responses to a language background questionnaire were followed by multiple-regression analyses. AOL accounted for an average of 59% of variance in the foreign accent ratings. Language use factors accounted for an additional 15% of variance. Gender was also found to influence degree of foreign accent.
Beach acoustics
Authors: Collins Michael D. , Coury Robert A. , Siegmann William L.
Published: October 2005

The parabolic equation method is modified to handle problems involving waveguides with sloping boundaries and applied to solve ocean acoustics problems in beach environments. Energy from a source in the ocean may propagate beyond the beach and be detectable several kilometers inland. Energy from a source buried several kilometers inland may couple into the ocean waveguide and be detectable many kilometers out to sea.
The effect of gas density on glottal vibration and exit jet particle velocity
Authors: Bielamowicz Steven , McGowan Richard S. , Berke Gerald S. , Kreiman Jody , Gerratt Bruce R. , Green David C.
Published: October 2005

Although theoretical studies include a term for gas density in their mathematical descriptions of glottal aerodynamics, the effect of gas density on glottal vibration has not been examined empirically. In this study, an in vivo canine model was used to evaluate the effect of gas density on glottal vibration by comparing phonation with air and helium. With gas flow and nerve stimulation held constant, phonation with helium resulted in an increased exit jet particle velocity for helium (45 m/s) compared to air (34 m/s). However, the measured increase in helium velocity was less than predicted by a proportional relationship between transglottal pressure and dynamic pressure. This difference could be due to a change in the constant of proportionality or in the dynamic pressure loss coefficient associated with the use of helium.
Guided plate waves in piezoelectrics immersed in a dielectric fluid. I. Analysis
Authors: Yang C.-H. , Chimenti D. E.
Published: October 2005

Calculation of the reflection coefficient of a piezoelectric plate immersed in a dielectric fluid is reported, extending previous work with an exact partial-wave analysis. It is demonstrated that the dielectric fluid case is a linear combination of the open-circuit and short-circuit conditions, with the fluid dielectric constant εf as a multiplier. As the dielectric constant goes to zero, the open-circuit case is recovered. For εf≫ε0, the behavior tends to the short-circuit case. Differences in mode coupling and behavior are illustrated in several calculated examples using LiNbO3.
Timbral aspects of reproduced sound in small rooms. I
Authors: Bech So/ren
Published: October 2005

This paper reports some of the influences of individual reflections on the timbre of reproduced sound. A single loudspeaker with frequency-independent directivity characteristics, positioned in a listening room of normal size with frequency-independent absorption coefficients of the room surfaces, has been simulated using an electroacoustic setup. The model included the direct sound, 17 individual reflections, and the reverberant field. The threshold of detection and just-noticeable differences for an increase in level were measured for individual reflections using eight subjects for noise and speech. The results have shown that the first-order floor and ceiling reflections are likely to individually contribute to the timbre of reproduced speech. For a noise signal, additional reflections from the left sidewall will contribute individually. The level of the reverberant field has been found to have an effect on the contribution of the individual reflections. An increase in the level of individual reflections are most likely to be audible for the first-order floor and ceiling reflections, and certain reflections from the sidewalls.
Three-dimensional effects in global acoustics
Authors: Collins Michael D. , McDonald B. Edward , Heaney Kevin D. , Kuperman W. A.
Published: October 2005

Low-frequency ocean acoustics problems are solved in three dimensions over the entire globe. Adiabatic mode solutions are obtained at 1 Hz using the parabolic equation method by marching through both the oceans and the continents from the location of the source to the antipode. The examples indicate that azimuthal coupling can be important for global-scale problems. One of the examples illustrates the broadening of a shadow behind the Hawaiian Islands by horizontal refraction. The other examples involve sources at the locations of the sources used in the Perth–Bermuda and Heard Island experiments.
Use of pitch-azimuth plots in determining the direction of a noise source in water with a vector sound-intensity probe
Authors: Hickling Robert , Wei Wei
Published: October 2005

A vector sound-intensity probe is used to determine the direction of a sound source in water. The probe consists of four pressure sensors in the tetrahedral arrangement, with each component of sound intensity measured simultaneously using the cross-spectral method. The probe dimensions are at least ten times less than the measured wavelengths. The probe has omnidirectional sensitivity with no 180 deg ambiguity. For plane waves, it is shown that direction finding with the vector probe is based on phase differences. Tests were conducted in a water tank to test the accuracy of direction finding of a sound source, with different types of noise interference. Results are expressed in the form of pitch-azimuth plots where the data points correspond to different frequencies in the frequency range of the measurements. These plots provide an all around three-dimensional view of the ambient sound field. Without interference the accuracy of direction finding is within ±2 deg. It is shown that, for an equivalent direction-finding capability, a vector intensity probe is two orders of magnitude smaller than a beamforming line array. It is suggested that vector sound intensity can be used to model directional hearing in animals.
Signal detection modeling of Japanese listeners’ /r/–/l/ labeling behavior in a one-interval identification task
Authors: Takagi Naoyuki
Published: October 2005

This study tested the validity of applying a signal detection model to Japanese listeners’ /r/–/l/ labeling behavior in a one-interval identification task, and the hypothesis that Japanese listeners estimate each token’s goodness of fit to Japanese /r/ in labeling it as /r/ or /l/. The identification data obtained by manipulating subjects’ response criteria fit the signal detection model. The performance in the identification task was highly predictable based on the goodness of fit judgment, indicating that category goodness information contained in /r/ and /l/ is utilized in deriving underlying sensory decision variables. The data, however, also suggested that these variables are not a direct consequence of the goodness of fit judgment. Various implications of the signal detection model in the investigation of Japanese perception of /r/ and /l/ are discussed.
Rise-time difference thresholds in the monkey
Authors: Prosen Cynthia A. , Moody David B.
Published: October 2005

Difference thresholds for changes in rise time were measured in monkeys at two standard stimulus durations, 250 and 500 ms, and with a fixed- or a variable-duration standard stimulus. Data suggested that (1) rise-time difference thresholds were larger with a variable- than a fixed-duration standard stimulus, (2) stimulus duration had a minor effect on thresholds, (3) the Weber fractions determined by the data were consistent with Weber fractions in the literature, and (4) monkey rise-time difference thresholds were larger than human rise-time difference thresholds.
Acoustics, perception, and production of legato articulation on a digital piano
Authors: Repp Bruno H.
Published: October 2005

This study investigated the perception and production of legato (‘‘connected’’) articulation in repeatedly ascending and descending tone sequences on a digital piano (Roland RD-250s). Initial measurements of the synthetic tones revealed substantial decay times following key release. High tones decayed faster than low tones, as they did prior to key release, and long tones decayed sooner than short tones because of their more extensive prerelease decay. Musically trained subjects (including pianists) were asked to adjust the key overlap times (KOTs) of successive piano tones so that they sounded optimally, minimally, or maximally legato. The results supported two predictions based on the acoustic measurements: KOTs for successive tones judged to be optimally or maximally legato were greater for high than for low tones, and greater for long than for short tones, so that auditory overlap presumably remained more nearly constant. For minimal legato adjustments the effect of tone duration was reversed, however. Adjusted KOTs were also longer for relatively consonant tones (three semitones separation) than for dissonant tones (one semitone separation). Subsequently, KOTs were measured in skilled pianists’ legato productions of tone sequences similar to those in the perceptual experiment. KOTs clearly increased with tone duration, an effect that was probably motoric in origin. There was no effect of tone height, suggesting that the pianists did not immediately adjust to differences in acoustic overlap. KOTs were slightly shorter for dissonant than for consonant tones. They also varied with position in the ascending–descending tone sequences, indicating that the pianists exerted strategic control over KOT as a continuous expressive dimension. There were large individual differences among pianists, both in the perceptual judgment and in the production of legato.