bluuebunny/crossref_metadata_2025 huggingface dataset:
The effects of clear speech on crossmodal speech perception
Authors: Gagné J. -P. , Querengesser Carol A. , Folkeard Paula
Published: October 2005

Six talkers were videotaped while they spoke a list of sentences twice: first while using conversational speech and then while using clear speech. The recorded stimuli were randomized (across talkers and type of utterances) and presented to three groups of subjects. Each group observed the stimuli under one of three experimental conditions: audio-only (A); visual-only (V); or, audio-visually (AV). For the two conditions in which the auditory signal was provided, a broadband noise was used to degrade the signal. The percent correct keyword recognition scores obtained from the subjects were used to determine the speech intelligibility of individual talkers. For each talker two speech intelligibility scores were obtained (in each sensory modality): one each for the tokens of conversational and clear speech. The results indicated that, in all sensory modalities, the talkers were more intelligible when they produced clear speech than when they used conversational speech.
Density of voicing information in purely temporal consonant identification
Authors: Baker Richard J. , Rosen Stuart
Published: October 2005

Speech waveforms containing purely temporal information (i.e., flat spectra and instantaneous amplitudes identical to natural speech, obtained by randomly changing the polarity of consecutive samples) contain quasiperiodic fluctuations in amplitude coincidental with voice periods. The temporal complexity of such waveforms can be reduced by half-wave rectifying the speech prior to removal of the spectral information. This study addresses the question of whether such simplification of the waveform improves the transfer of voicing information in a VCV context in normal hearing adults. The results of consonant identification experiments will be presented in which (a) the two polarities of half-wave rectification are compared to the unrectified condition (equivalent to full-wave rectification) and (b) the waveforms are low-pass filtered at the upper extreme of the fundamental frequency distribution of the speaker, prior to full-wave or half-wave rectification and removal of spectral information. Such filtering removes much of the quasi-periodicity arising from voicing in the full-wave rectified condition. [Work supported by the MRC UK.]
CSRE: A speech research environment
Authors: Jamieson Donald G. , Ramji Ketan , Kheirallah Issam , Nearey Terrance M.
Published: October 2005

CSRE (The Canadian Speech Research Environment) is a comprehensive, microcomputer-based system designed to support speech research using IBM/AT-compatible micro-computers. CSRE provides a powerful, low-cost facility in support of speech research, using mass-produced and widely available hardware. Functions include speech capture, editing, and replay; several alternative spectral analysis procedures, with color and surface/3-D displays; parameter extraction/tracking and tools to automate measurement and support data logging; alternative pitch-extraction systems; parametric speech (KLATT80) and nonspeech acoustic synthesis, with a variety of supporting productivity tools; and a comprehensive experiment generator/controller, to support behavioral testing using a variety of common testing protocols. The CSRE project is nonprofit, and relies on the cooperation of researchers at a number of institution. Version 3.0 of CSRE has been used since 1989 by researchers in 12 countries. Version 4.0 offers a wider range of functions, runs faster, uses higher resolution displays, and supports additional hardware systems, including digital signal processing boards.
On the acoustic probing of the sea bottom in shallow water from near-field data
Authors: Lambert Marc , Lesselier Dominique
Published: October 2005

The probing of the acoustic profiles of the seabed in shallow water from the sound pressure observed on a line array in presence of a cylindrical source, is dealt with. The seabed is modeled as a depth-inhomogeneous fluid sediment overlying an homogeneous fluid subbottom. As is well known, the propagation is characterized by the depth-dependent Green’s function in the horizontal wave-number (spectral) domain, which is a function of the plane wave reflection coefficient of the seabed, with extension to wave numbers larger than the one of water. Conversely, seabed parameters are sought by analyzing features of the Green’s function, such as location and magnitude of peaks with then measurements needed in the far field. Here, using receivers near the source, where the ‘‘continuum’’ part of the field is preponderant, directly provides an estimate of the reflection coefficient (at least at low wave numbers). This allows the application of solution methods of the 1-D inverse scattering problem, with limitations due to the discrepancy between estimate and true coefficient. Corresponding issues: retrieving the reflection coefficient, probing the parameters profiles, are investigated and illustrated by examples taken in various source, array, and seabed configurations.
Finite difference modeling of geoacoustic interaction at anelastic seafloors
Authors: Stephen R. A. , Swift S. A.
Published: October 2005

A major problem in understanding sound propagation in the seafloor is to distinguish between the loss of energy due to intrinsic attenuation (anelasticity) and the loss of energy due to scattering from intermediate scale heterogeneities and bottom roughness. Energy lost to intrinsic attenuation (heat) disappears entirely from the system. Energy lost to scattering is conserved in the system and can effect observations as incoherent noise (time spread, angle spread) and/or mode converted waves. Dougherty and Stephen (1988, 1991) showed that the finite difference synthetic seismogram method can be applied to the seafloor scattering problem. Recently, this two-dimensional finite difference code has been extended to include intrinsic attenuation using the formulation of Day and Minster (1984). The formulation assumes a stress–strain relation for which Q is independent of frequency over a specified bandwidth. For each node on a two-dimensional grid arbitrary values of compressional and shear Q can be specified in addition to the usual values of compressional and shear velocity and density. Fluids are represented by setting the shear modulus to zero. Q’s computed from the output time series are in good agreement with the input values for homogeneous media. Now by forward modeling the trade-off between scattering and intrinsic attenuation in seafloor models with both surface roughness and volume heterogeneities can be studied. Results can be compared with field observations from vertical seismic profiles (VSP’s) in the seafloor and marine refractions experiments.
Tube waves, seismic waves, and effective sources
Authors: Burridge R. , Kostek S. , Kurkjian A. L.
Published: October 2005

The radiation of waves from a monopole source in a fluid-filled borehole into an elastic medium is considered. A simple asymptotic analysis, based on the smallness of the ratio of the borehole radius to the wavelength, reveals the interaction between tube waves and seismic waves. The pressure field in a tube wave acts as a secondary source of seismic waves and conversely an incoming seismic wave excites a tube wave. The asymptotic analysis leads to a characterization of these sources in terms of the solution to two-dimensional elastostatic problems. These may be solved exactly when the borehole has an elliptical cross section even in an anisotropic formation. Also the borehole need not be straight provided that its radius of curvature is large compared with a wavelength. The problem of two boreholes, one containing a source and the other a receiver (crosswell tomography geometry) is analyzed and an explicit expression for the received signal is derived.
A preliminary test of prototype theory for a [ba]-to-[da] continuum
Authors: Sussman Joan E.
Published: October 2005

Ten listeners participated in identification, overt prototype [A. Samuel, Percept. Psychophys. 82, 307–314 (1982)] and selective adaptation tasks for a 15-item continuum. Stimuli varied linearly by 90- and 178-Hz steps of formant frequency transition onsets for the second and third resonances, respectively. The prototype was defined as the ‘‘best example of ba’’ with ‘best’ explained per Samuel [1982, p. 309]. Results showed significant intra- and inter-subject variability for prototype choice. Each subject consistently chose his/her prototype on average 39% of the time, ranging from 20%–53%. Subjects chose stimuli 2–8 as prototypes, with the highest number (3) choosing stimulus 3 along the continuum. Further, contrary to Samuel’s (1982) results for a [ga]–[ka] continuum, the greatest selective adaptation shift was obtained for the most extreme [ba] adaptor (average shift of 8.7%), with the prototype (average shift of 6.5%) and boundary adaptors (average 5.3% shift) resulting in smaller shifts. Results including reaction time data, will be related to prototype theory for consonant categories.
An exploration of phoneme structure and models of classification for place of articulation
Authors: Li Xiaofeng , Cho Jennifer L.
Published: October 2005

Speech perception research has typically investigated phoneme categories and specified trading relation effects in terms of limits defined along single dimensions. However, phoneme categories vary along a number of significant physical dimensions, with stimuli distributed across the multidimensional perceptual space often differing in goodness of category membership. The current study used a set of synthetic CV syllables based on F2- and F3-onset frequencies to examine the internal structure of several phonetic categories within the same vowel context. Experiment 1 used a free classification task to establish the perceptual structure of categories differing in place of articulation. Experiments 2, 3, and 4, respectively, related response times of a speeded classification task with category goodness ratings and a multidimensional phonetic perceptual space based upon similarity ratings. The multidimensional space was quite distinct compared to a prior space obtained for a different vowel context. Results are discussed in terms of prototype and exemplar models of phonetic classification. [Research supported in part by grants from NSF and AFOSR to R. E. Pastore, and NIH.] a)Now at Indiana University.
Short-term IWAIF model for frequency discrimination
Authors: Krishnamurthy Ashok K. , Feth Lawrence L.
Published: October 2005

The intensity/envelope weighted average of instantaneous frequency (IWAIF/EWAIF) has been used to model listener performance in complex signal discrimination [Feth, J. Acoust. Soc. Am. Suppl. 1 88, S48 (1990)]. Previous work with this model has used the entire signal duration for the IWAIF computation. However there exist pairs of signals such as the STEP and GLIDE signals used by Madden and Feth [Feth etal., J. Acoust. Soc. Am. Suppl. 1 86, S122 (1989); Madden and Feth, J. Speech Hear. Res. 35, 436–442 (1992)] that have the same long-term IWAIF values, but are nonetheless readily discriminable by listeners. The addition of a short-term running IWAIF computation extends the application of the IWAIF model to such dynamic signals. Also described is an ideal detector for the short-term IWAIF model that assumes that independent, white, Gaussian internal noise is added after the IWAIF computation. The noise variance is derived from frequency DL (FDL) data. It is shown that this detector is able to predict listener performance in the STEP versus GLIDE discrimination task. Applications of the short-term IWAIF model in deriving frequency modulation DL (FMDL) from the FDL are also presented. [Work supported by AFOSR.]
Intermediate detection of changes in modulation and power spectra
Authors: Richards Virginia M. , Sanderson Mark Ian
Published: October 2005

In an effort to examine the shift from modulation-based discrimination for narrow-band complex stimuli to across-frequency spectral comparisons for wideband complex stimuli, the mutual discriminability of 11 stimuli was determined. The five ‘‘base’’ stimuli were the sum of three tones. By altering the relative phases of the tones, modulation depths ranging from maximum (SAM) to minimum (QFM) were generated using five equal log steps. The central frequency was 1000 Hz, and modulation rates ranged from 20 to 240 Hz. Three additional stimuli had envelopes identical to three of the base stimuli, but had periodic fine structures. Three other stimuli had fine structures identical to three of the base stimuli, but no envelope modulation. For observers tested thus far, where the modulation rate was 20 Hz, discriminability is well described as being based on changes in modulation depth. Where the modulation rate was 240 Hz, the discrimination appears to depend on changes in long term power spectra. For intermediate modulation rates, the data do not appear to reflect a gradual change from modulation-based detection to power spectrum-based detection, but the intervening cues appear not to be well defined by our stimuli.
Analysis of vibration transmission through joints using component modes
Authors: Farstad Jerry E. , Singh Rajendra
Published: October 2005

In many cases, the most practical approach for reducing noise in built-up machine assemblies is to reduce the vibration transmitted through joints to the machine housing as much as possible. In this paper, a new analysis framework for estimating the vibration transmitted among machine components joined at discrete locations in vibrating assemblies is presented. The method is based on a recently developed modal synthesis approach. Natural frequencies and modes of the disassembled components subject to specific boundary conditions applied at the joint locations are used to compute the natural frequencies and modes of the assembly from a variational formulation. Lagrange multipliers are used to enforce the constraints that motions of components at joint locations be identical. The modal properties of the assembly are then used to compute its forced response. Since the Lagrange multipliers used to enforce the constraints represent the interfacial joint forces, evaluating these from the forced response provides an efficient way of computing the dynamic power transmission among components, which is probably the best measure of transmitted vibration. In addition to theory, a simple example of an assembly of two lumped parameter systems is included.
An experimental investigation of the nonlinear interaction of noncollinear sound beams
Authors: Roy Ronald A. , Wu Junru
Published: October 2005

The nonlinear interaction between two pulsed, Gaussian ultrasonic beams propagating through degassed and filtered water was studied. One beam had a center frequency of 3.5 MHz and a peak pressure amplitude (in the interaction region) of 450 kPa. The other possessed a center frequency and peak pressure amplitude given by 3.0 MHz and 320 kPa, respectively. With the axes of the beams intersecting perpendicularly in the near-field, no sum-frequency scattered pressure amplitude greater than 0.03 Pa was detected outside the interaction region. The insertion of a brass sphere into the center of the interaction region resulted in the generation of two partially collinear scattered beams, and a sum-frequency scattered signal level of 0.9 Pa was subsequently detected at a 45±0.5° scattering angle. Experiments with collinear beams generated using a single projector driven by two electrically summed tone bursts (center frequencies=3.0 and 3.5 MHz) indicate the production of sum and difference frequencies in quantitative agreement with Westervelt’s theory for the parametric end-fire array [J. Acoust. Soc. Am. 32, 934A (1960)]. [Work supported by APL IR Funds.]
Acoustic nonlinearity parameter inversion from harmonic interaction
Authors: Plona T. J. , Kostek S. , Kimball C. V. , D’Angelo R.
Published: October 2005

This paper is concerned with the measurement of the acoustic nonlinearity parameter of fluids (β=1+B/2A) using harmonic interactions of finite amplitude acoustic waves. The data consist of the on-axis pressure field emanating from a planar circular transducer, measured by a small probe. The source is excited by either a single frequency signal (f) or by a composite signal of two frequencies (f1 and f2). The attenuation of the fluid is measured independently by a standard linear wave propagation technique. The model for predicting the finite amplitude pressures is the Kuznetsov–Zabolotskaya–Khokhlov equation (KZK), which has been used extensively to model nonlinear acoustic beam fields. By taking the pressure measurements just beyond the Rayleigh distance, and providing that the sound pressure level is not too high such that the measurements are taken within one shock formation distance, a quasilinear approximation to the KZK equation is used, which is sufficiently accurate to represent the first-order interactions (2f, f1+f2, f1−f2, etc.) and computationally efficient, thus rendering the one-parameter inversion problem manageable. The accuracy of the inversion technique will be discussed for data consisting of both second-harmonic and difference frequency signals. Results for various fluids will be shown and discussed.
The radial oscillations of a gas bubble in a surfactant solution
Authors: Tian Yuren , Zheng Xiaoyu , Holt R. Glynn , Apfel Robert E.
Published: October 2005

In a surfactant solution, a gas bubble can be covered by an adsorbed film of surfactant. When the bubble is excited into radial oscillations by a sound field, the surface concentration of the surfactant varies with the surface area and the mass interchange between the surface and the bulk liquid. As a result, the surface tension becomes a function of the bubble radius. Previous theoretical work on this subject [R. E. Glazman, J. Acoust. Soc. Am. 74, 980–986 (1983)] will be commented on and the equations governing the radial oscillations for this kind of gas bubble will be discussed. By numerically solving the equation under different initial bubble sizes, sound pressures, and driving frequencies, one can determine the effects of variable surface tension, surface viscosity, and surface mass transfer on the motions of the gas bubble. Thresholds of transient cavitation will also be estimated by including these effects. [Work supported by NASA through JPL, Contract No. 958722.]
Rayleigh wave nonlinearity
Authors: Hamilton Mark F. , Il’insky Yuri A. , Zabolotskaya Evgenia A.
Published: October 2005

The elastic nonlinearity in Rayleigh waves is investigated theoretically. Studies have revealed that nonlinearity in Rayleigh waves involves nonlocal as well as local effects [Parker and Talbot, J. Elast. 15, 389 (1985)]. Finite amplitude effects on sound in fluids are entirely local, and the effects on different wavelets are therefore independent. In contrast, the effects of nonlocal Rayleigh wave nonlinearity on a given wavelet are influenced by the properties of the entire wave. A time-domain evolution equation for Rayleigh wave propagation on the surface of an isotropic solid reveals the existence of nonlocal nonlinearity [Zabolotskaya, J. Acoust. Soc. Am. 91, 2569–2575 (1992)]. In the present study, the nonlinear operator in the evolution equation is investigated numerically and analytically. Numerical results show the dependence of the nonlinearity on the global properties of the waveform. An explicit analytical expression derived for the nonlinear operator permits the local and nonlocal contributions to be easily distinguished. Local versus nonlocal effects on waveform distortion are discussed. [Work supported by the David and Lucile Packard Foundation and by ONR.]
Offset dominance in pitch perception
Authors: Aoki Shigeaki , Houtgast T.
Published: October 2005

Possible effects of onset or offset dominance for pitch information are investigated with the same experimental approach, which clearly showed the familiar onset dominance in the perception of binaural cues [Houtgast and Aoki, J. Acoust. Soc. Am. Suppl. 1 87, S64 (1990)]. A brief stimulus, with a duration of 5, 10, 20, or 40 ms, is subdivided in two parts with durations T1 and T2, each part consisting of a sinusoidal signal of either 1 or 2 kHz. The measuring paradigm aims at assessing the critical ratio T1/T2 for which both parts contribute equally to the overall sensation of pitch for these brief stimuli. This critical ratio is found to be greater than one, indicating a dominance of the pitch information presented in the later part of the stimulus. The data can be summarized in a weighting function: the perceptual weight of the pitch information as a function of time before signal offset. This weighting function shows a peak of enhanced weight for the last few milliseconds just before stimulus offset, in contrast with the enhanced weight for the first few milliseconds following stimulus onset as found previously in case of binaural cues.
Decision rules in spectral-shape discrimination with and without signal uncertainty
Authors: Dai Huanping
Published: October 2005

In typical profile-detection tasks there is little difference, about 3 dB in signal-to-standard ratio, between signal threshold when the signal frequency is fixed (signal known) and when the signal frequency is randomly selected on each trial (signal unknown). For an ideal observer, this difference should be 8 dB when using 21 components. One hypothesis about the discrepancy between the human and ideal observer is that, for the human observer, the central noise (e.g., fluctuations of the decision criterion) is much greater than the peripheral noise. This assumption can account for both the slope of the psychometric function obtained in conditions when the signal frequency is known and the relatively small threshold difference between the signal-known and signal-unknown conditions. [Work supported by NIH.]
Effects of simulated aircraft noise on heart rate and behavior of desert ungulates
Authors: Krausman Paul R. , Wallace Mark C. , Weisenberger Mara E. , DeYoung Donald W. , Maughan O. E.
Published: October 2005

The effects of simulated low-altitude jet aircraft noise on the behavior and physiology of 6 captive desert mule deer (Odocoileushemionuscrooki) and 5 mountain sheep (Oviscanadensismexicana) were evaluated. Heart rate and behavior in relation to ambient temperature, number of simulated overflights/day, and noise levels [range =92–112 decibels (dB)] that the animals were exposed to were measured. Heart rates during simulated overflights (n=112/treatments/season) were compared to data collected prior to and following treatment periods. Differences between heart rates for animals, noise levels, and number of overflights between seasons were documented. All animals became habituated to sounds of low-altitude aircraft. Although heart rates increased during overflights they returned to resting rates in ≤2 min.
Effects of aircraft noise on time-activity budgets of wintering black ducks
Authors: Conomy John T. , Collazo Jaime , Fleming W. James
Published: October 2005

The primary goal of this study was to determine if the time-activity budget (TAB) of wintering black ducks (Anasrubripes) was significantly altered by military aircraft noise at the U. S. Marine Corps target range in Piney Island, North Carolina. Sound levels were measured concurrently with behavioral observations. Over a sampling period of 81 days, exceedances ≳80 dB occurred on 289 occasions, the mean duration of exceedances was 5.09 s, and the mean sound pressure was 85.7 dB. Black ducks spent between 0.2% and 0.5% of their time reacting to aircraft. Correspondingly, the energetic costs of these reactions were low. TABs of black ducks in the high noise environment of Piney Island were within the expected range of those in low noise environments based on published literature. In a follow-up study, captive black ducks were subjected to simulated jet noise at levels approximately those recorded in the field. Measured levels of reactions to noise stimuli indicated that ducks habituated within 1 day. These results suggest that low reaction levels recorded in the field reflect the species’ habituation capabilities to some kinds of disturbance. [Work supported by USMC and USAF.]
A method for measuring wildlife noise exposure in the field
Authors: Kugler B. Andrew , Barber David S.
Published: October 2005

The effects of aircraft noise on wildlife have received much attention from the environmental community, especially when associated with low altitude aircraft overflights. In the past, much of the research on this subject used surrogate information to describe noise events in field studies. For example, noise exposure was often measured at an observer location, far removed from the animal under study, or inferred from the presence of aircraft flyovers. This paper describes the development and application of an animal noise monitor (or ANM) that can be mounted on a collar and worn by a subject animal over extended periods of time. The approach allows for measurement of noise exposure of the animal whose behavior is being observed, without external interference other than initial capture. The device is capable of recognizing aircraft noise events, calculating a variety of acoustic descriptors associated with these events, and retaining the information in memory for up to 6 months until the ANM is recovered from the field. The ANM, in addition to time- and date-stamping of each event, also contains a monitor that can measure and record the activity of an animal during and immediately after a noise intrusion. The ANM is capable of withstanding harsh environments and operates over a wide temperature range. This instrumentation has been used recently on a caribou noise effects study in Alaska.
Breaking waves and bubble plumes
Authors: Dahl Peter H. , Jessup Andrew T.
Published: October 2005

A large part of our knowledge of oceanic bubbles originates from acoustic measurements, for example, boundary layer stability [Thorpe, Philos. Trans. R. Soc. London Ser. A 304, 155–210 (1982)] and Langmuir structure [Zedel and Farmer, J. Geophys. Res. 96 (C5), 8889–8900 (1991)] are known to influence bubble field properties. What remains elusive are details of the transient properties of the bubble field, such as the spatial and temporal scale of bubble plumes due to breaking waves. During January 1992 acoustic measurements of bubble plumes from breaking waves were made from the R/P FLIP operating 400 nmi. Off the coast of California. Acoustic measurements were made from two sonars, a four-beam system (20–50 kHz) and a single-beam system (240 kHz), placed at the end of a 12-m subsurface boom attached to FLIP’s hull at 28.5-m depth. The subsurface boom was specifically designed for this application, allowing the sonars to look up at the ocean surface from a stabilized platform. To document breaking wave activity over the acoustic system, a video camera was mounted on FLIP’s aft boom and trained upon the acoustic footprint on the ocean surface. Surface waves, CTD, current, and meteorological measurements were also made. Space-time images of acoustic volume scattering clearly show bubble plume growth and decay. Details of the spatial and temporal scales of transient bubble plume and breaking wave event combinations are presented. In one case characterized by U10=10 ms and H1/3=2.3 m, newly generated bubble plumes were observed to reach a maximum depth of approximately 4 m in about 60 s after wave breaking occurred. [Work supported by ONR Code 124.]
Coherent and incoherent scattering from oceanic bubbles
Authors: Sarkar Kausik , Prosperetti Andrea
Published: October 2005

In recent years, an effective medium theory has been applied to model the contribution of bubbles for low-frequency oceanic backscattering [Prosperetti etal. and Sarkar and Prosperetti, both submitted to J. Acoust. Soc. Am.] This approach differs from the more traditional one used to account for the effect of bubbles at higher frequencies, in which bubbles are treated as individual scatterers. Here, the relationship between these two apparently different approaches is clarified and a unified theory is presented. In this way, a better understanding of the rationale and limitations for the older theory is achieved. Applications to scattering and bubble counting are described. [Work supported by ONR.]
Dynamic mechanical properties of violin wood and the tone qualities of violins. II: Relation of dynamic mechanical properties to the plate tuning of violins
Authors: Hutchins Carleen M. , Hutchins Morton A. , Fitzgerald Edwin R.
Published: October 2005

Desirable mechanical properties of density, vibrational damping, Young’s modulus, velocity of sound, and the ratio of velocity to density for spruce tops and maple backs of violins have been fairly well established [I. Barducci and G. Pasqualini, Nuovo Cimento 5 (5), 416–466 (1948); J. C. Schelleng, J. Acoust. Soc. Am. 35, 326–338 (1963); F. Rocaboy and V. Bucur, Catgut Acoust. Soc. J. 1 (6) (Ser. II), 21–28 (1990)]. However the longitudinal to cross grain ratios of Young’s modulus and the shear modulus, as well as their relationships in both spruce and maple have not been studied extensively. This work is concerned with the extent to which these ratios can vary and still make possible the optimum plate tuning of modes ♯1, ♯2, and ♯5 in violin top and back free plates. From a 1975 shipment of commercially available German spruce and maple, ten sets of violin top and back flitches were built into 10 normal violins. The plate tunings of six sets of these will be charted and discussed in relation to their mechanical properties.
Further evidence for activation of sublexical units in spoken word recognition
Authors: Lyons Emily A. , Luce Paul A.
Published: October 2005

At the previous meeting of the Society, data from an auditory lexical decision experiment were presented that demonstrated that subjects are faster to respond to bisyllabic words in which the first syllable is a word (e.g., KIDNEY) than to bisyllabic words in which the first syllable is a nonword (e.g., CHIMNEY). These findings suggest that the activation of component lexical items embedded in longer words has demonstrable effects on recognition time. Data from a single word shadowing experiment will be presented that replicate the previous findings from auditory lexical decision. These results provide further evidence for activation of sublexical units in spoken word recognition and demonstrate that sublexical activation has facilatory—not inhibitory—effects on recognition time. [Work supported by NIH Grant No. DC-00879-01 to the State Univ. of New York at Buffalo.]
Age-related differences in the discrimination of two-formant transitions
Authors: Fox Robert Allen , Chaudry Fauzia , Wall Lida
Published: October 2005

In the past 3 years age-related differences in the ability to process rapidly changing acoustic information (e.g., formant transitions) in making phonetic decisions (e.g., identification of consonants and/or vowels) have been investigated. The data obtained in these studies have been consistent with the claim that older adults as well as children show a decreased ability to process dynamic acoustic information, compared to that of young (college-aged) adults. The present study examines age-related differences in the discrimination of several synthesized two-formant transition and steady-state continua. Two continua represented a [wi]-[w(eh)]-[wæ] continuum (differing in terms of the duration of the transition) and the last set of stimuli represented a [bɑ ]-[dɑ ] continuum. Three groups of listeners (children 9–12 yrs, young adults 19–25 yrs, and older adults 58–71 yrs) were required to discriminate between two stimulus tokens using a version of Levitt’s up–down adaptive procedure. Significant differences were found between the age groups with the lowest jnd’s found in the young adults. However, phonological considerations (e.g., changing location of phoneme boundaries across stimulus types) also had a significant effect on jnd’s. These data will be discussed with regard to possible explanations of developmental differences (in the case of children) and aging differences (in the case of older adults). [Work supported, in part, by a grant from the National Institute on Aging No. 5R01 AG08353-04.]
Allophonic constraints and segmentation in infant speech perception
Authors: Hohne Elizabeth A. , Jusczyk Peter W.
Published: October 2005

The role of allophonic constraints in speech perception was studied with 2-month olds and adults. English word and nonword stimuli were selected to have the same phonemic content, but different allophonic structure. In particular, some of the stimuli contained an allophone of the phoneme category /t/ that is used in signaling a boundary between two words (e.g., the /t/ in ‘‘night rate’’), whereas others contained an allophone appropriate to the middle of a word (e.g., the /t/ in ‘‘nitrate’’). Two-month old infants discriminated allophones corresponding to different word and nonword boundary locations. When vowel duration and other prosodic variables surrounding the allophones were equated, infants continued to discriminate them. These results suggest that the basis for discrimination is not simply prosodic in nature. The adult data, measured by a same/different discrimination task, differed from the infant data in the patterning of responses. There is some indication the adult data can be explained in terms of lexical effects. [Work supported by NICHD.]
Detection of transients using the nonstationary bispectrum
Authors: Barlett Martin L. , Baugh Kevin W. , Wilson Gary R.
Published: October 2005

An algorithm based on the nonstationary bispectrum is proposed for detection of sampled finite duration signals. The detection algorithm uses a combination of coherent and incoherent smoothing in the frequency domain to produce a test statistic which is suitable for display as a spectrogram. A model transient waveform imbedded in Gaussian noise is used to evaluate the detection performance of the proposed detector. Detectors based on the spectral correlation and power spectrum are used as metrics to evaluate the relative effectiveness of the proposed detector. Performance is investigated both as a function of signal-to-noise ratio for a fixed transient duration and processing length and as a function of transient duration/processing length mismatch at a fixed signal-to-noise ratio. The benefits and limitations of the proposed test statistic based on the nonstationary bispectrum relative to the other detectors investigated will be noted. [Work supported under contract with Space and Naval Warfare Systems Command.]
Target tracking using matched-field processing
Authors: Wilmut Michael J. , Ozard John M. , Woods Bryan
Published: October 2005

The objective of this paper is to illustrate the use of matched-field processing (MFP) for tracking low signal-to-noise ratio targets moving linearly and at constant speed. The input to the tracker consists of the positions and power of the largest peaks on the MFP ambiguity surface. These largest peaks usually include the match at or near the source position even at low signal-to-noise ratio. An exhaustive search for the best matching track over all possible target tracks (that is allowing varying speed and heading) is beyond the scope of today’s computers for any realistic search region. In this paper, an efficient algorithm is described based on examining the average Bartlett statistic along a set of linear tracks that connect only the largest peaks. This set was restricted to the physically possible tracks to further reduce the number to be examined. Examples of the ambiguity surfaces and the probability of examining the true track are given. The algorithm performance is a function of the scenario, signal-to-noise ratio, number of ambiguity surfaces, and number of peaks examined on each surface. It is shown that if the true target track is one of those examined its Bartlett statistic is almost certainly maximum. This efficient tracking requires only modest computing beyond that required to generate the ambiguity surfaces.
Further comments on beamforming with acoustic measurements at a single point in the ocean
Authors: D’Spain G. L. , Hodgkiss W. S.
Published: October 2005

Previously, the idea of using multi-component acoustic measurements at a single point in the ocean, rather than spatially distributed measurements of pressure, to obtain information on the spatial dependence of the ocean acoustic field was introduced [G. L. D’Spain and W. S. Hodgkiss, J. Acoust. Soc. Am. 91, 2364(A) (1992)]. The basis for this single-point measurement approach is a Taylor series expansion of the pressure field. The purpose of this presentation is to further extend these ideas, including the use of adaptive time-varying array weights to perform correlated noise cancellation and the application of Capon’s minimum variance method to measurements in a second order Taylor series expansion. In addition, ways of processing the data collected by a line array of multicomponent sensors in order to eliminate spatial aliasing when the interelement spacing is somewhat greater than the half-wavelength criterion will be presented. Finally, the application of high-resolution beamforming techniques with actual multi-component (hydrophone and geophone) data for the determination of the azimuthal directionality of the underwater sound field below 5 Hz in several experiments will be discussed. [Work supported by ONR and ONT.]
Beamforming towed array data when knowledge of the hydrophone positions is imperfect
Authors: Ferguson Brian G.
Published: October 2005

Information on the various sound sources that contribute energy to the underwater acoustic environment is often obtained by processing the data from a thin flexible line array of hydrophones towed behind a vessel. The acoustic data from the array are processed digitally in the frequency and spatial domains. The process of spatial filtering, which is commonly referred to as beamforming, assumes that the horizontal line array is straight with the transverse displacements of the hydrophones being zero with respect to the array axis. Using real acoustic data, this paper shows the effects on conventional and adaptive beamformers when these transverse displacements are finite and the array shape is nonlinear. Furthermore, signal processing techniques are presented that significantly reduce the influence of these effects on the performance of the beamformers. By processing the array’s acoustic data when a plane-wave acoustic source is present, these techniques estimate the horizontal and transverse displacements of the hydrophones for subsequent input to the spatial filters.
Attentional effects on phonetic encoding of acoustic cues
Authors: Gordon Peter C. , Pyatt Elizabeth J.
Published: October 2005

The role of attention in the phonetic encoding of acoustic cues was studied by examining the effect of a nonspeech distractor task on listeners’ classification of the speech sounds /ra/ and /la/. Consistent with previous results [Gordon etal., Cog. Psychol. 25 (1993)] it was found that the impact of a relatively strong cue (F3 transition) on phonetic classification was reduced when listeners could not devote full attention to the speech sound. In contrast with previous results, the impact of a relatively weak cue (an aperiodic burst during the formant transition) was also reduced when full attention was not possible. This result conflicts with models in which the importance of attention in phonetic encoding is greater for acoustic cues whose phonetic importance is very great. It suggests that the role of attention in phonetic encoding depends on specific characteristics of acoustic cues.
The distinctiveness of word onsets
Authors: Gow David W. , Gordon Peter C.
Published: October 2005

Acoustic measurements examined the distinctiveness and salience of word onsets and matched syllables that occurred in non-word-initial position. Three naive speakers rehearsed and read phonemically identical one- and two-word sequences such as ‘‘cartel’’ and ‘‘car tell’’ under three conditions: citation form, read slowly in sentenial context, or read quickly in sentenial context. Analyses examining the timing of segments and syllables, and the degree of vowel reduction under each condition showed that word-initial syllables were longer, and showed less vowel reduction than their non-word-initial counterparts. These results suggest that word onsets differ acoustically from nonword onsets in a manner that may enhance their perceptual salience. These results are discussed in relationship to the Good Start model of lexical access and lexical segmentation. [Work supported by AFOSR.]
Loudness adaptation in listeners with high frequency impairment
Authors: Janson Jennifer L. , Weiler Ernest M. , Sandman David E. , Shiau Yea-Wen , Nelson Todd , Warm Joel , Stromberg Eleanor
Published: October 2005

High-frequency impairment was found to have a significant effect on ipsilateral loudness magnitude adaptation in complex interactions [Korman etal., J. Acoust. Soc. Am. Suppl. 1 81, S76 (1987)]. The present study used simple comparisons of 12 listeners with high-frequency hearing loss, age matched with 12 having no loss. All were tested at 1 kHz for adaptation at 40 and 60 dB HTL. [See Weiler etal., Brit. J. Audiol. 15, 204–205 (1981).] The hearing loss group showed significantly more adaptation at 40 dB than at 60, while normals showed the same amount. Based on the two studies, it appears that high-frequency hearing loss does have some effect on the loudness function at 1 kHz where hearing appears to be normal.
Enhancement of cochlear signal cell and CM responses after exposure to an intense tone or noise
Authors: Pietras Bradley W. , Zwislocki Jozef J.
Published: October 2005

The phenomenon of decreased cochlear sensitivity after exposure to intense noise is well known. It predominantly affects low levels of stimulation and, when not too severe, it usually exhibits sensitivity recruitment at higher levels. By contrast, in Mongolian gerbils, enhanced receptor potentials of outer hair cells have been found, as studied through intracellular recording from Hensen’s cells. According to previous studies, alternating potentials of the latter faithfully reflect those of the former. The enhancement affected mainly high levels of stimulation, and was practically absent in low level responses. It did not seem to affect the shapes of Hensen’s cells’ transfer functions. It was present at the cochlear location of 2 kHz BF after exposure to either a 1-kHz tone or a broadband noise, both at 100 dB SPL. It increased over exposure durations as long as 60 to 90 min and decreased slowly after exposure termination. The enhancement did not appear to be correlated with fluctuations in Hensen’s cell resting potentials or the endolymphatic potential. It was weak when measured in CM. [Work supported by NIDCD.]
A modal power balance approximation for point connected flexural beams
Authors: Kasper Peter , Bremner Paul , Constantine Paris
Published: October 2005

In recent years, the application of power flow techniques to the analysis of beams and plates has led to an increased understanding of how noise is transmitted through structures. When applied in terms of mode-to-mode transmission, power flow evaluation has promise in modeling dynamic response at frequencies for which statistical energy analysis is not appropriate. Modal power flow calculations can, however, be computationally prohibitive. This paper introduces a modal power balance approach by which the computational effort can be reduced. The approach involves formulating the mode-to-mode power exchanged between two beams in terms of a set of modal power balance equations. These equations are analogous to the sub-system power balance equations of statistical energy analysis. By introducing suitable approximations, the equations can be integrated over frequency and length to express power flow relationships in terms of band-limited, modal mean-square values. The approach is applied to the configuration of two force and moment coupled flexural beams. The results are compared with a classical modal solution.
Identification of structural power flow for multiple correlated sources
Authors: Wagstaff Peter , Jin Mei , Bouizem Boudjema
Published: October 2005

Structural intensity measurements may be used to identify the direction of propagation of vibrations in single and multiple source situations. In the latter case standard techniques do not permit the individual contribution of each source to be identified. Previous publications have presented the results of experiments carried out at Compiègne using selective intensity techniques which are based on multiple input multiple output models for partially correlated inputs. These techniques break down when the inputs are highly correlated. In order to solve this problem and to simplify the measurement of the reference signals for the inputs a method has been developed to estimate the structural intensity due to each source based on the use of the frequency response function matrix associated with specific points on the structure. The inputs to the structure are initially identified using a pseudo-inverse of the measured data and the intensity due to each input may then be estimated using the original data and eliminating the terms due to the effects of the other inputs. Results are presented for a simple structure with two inputs.
Vibro-acoustic power flow in plate–fluid layer systems
Authors: Önsay Taner
Published: October 2005

Attenuation of flexural vibrations by viscous compressible fluid layers is studied by using a power flow analysis. A fluid layer trapped between vibrating surfaces may increase low-frequency damping and cause significant changes in the dynamic behavior of a coupled plate. A prototype system consisting of a clamped plate and a coupled finite air layer is analyzed by using a transfer matrix method. Spectral and spatial distributions of power flow are obtained at different layer thicknesses. Particular attention is given to various dynamic regimes of the fluid layer. Significance of the viscous shear forces and compressibility during the dissipative-to-stiffness transition of the fluid layer are emphasized. At very small layer thicknesses, the increased flow resistance caused by viscous shear forces resulted in local stiffening of the fluid layer which blocked the transmission of the vibrational power. Contributions from three different power flow components, shear, bending and acoustic, are discussed in reference to the dynamic interactions of flexural waves with the fluid layer. The results obtained for different system configurations are briefly reviewed.
Experiments and analysis of shape oscillations of bubbles levitated in water on the Earth
Authors: Asaki Thomas J. , Marston Philip L.
Published: October 2005

Levitation and excitation of shape oscillations for bubbles in water were demonstrated for the size range 1.6 to 12-mm diameter [T. J. Asaki, P. L. Marston, and E. H. Trinh, J. Acoust. Soc. Am. 93, 706–713 (1993)]. Novel methods of experimentation and analysis in the current research should complement experiments carried out in microgravity. Current research concerns the understanding of equilibriuim shape effects on steady-state and freely decaying shape oscillations. These oscillations were studied with an optical extinction method. The measurements probe the surface rheology of the bubble. The experimental method has been shown to be applicable to saline solution as well as to degassed but otherwise untreated sea water. [Research supported by ONR and DOE GAANN fellowship.]