bluuebunny/crossref_metadata_2025 huggingface dataset:
The development role of interspeaker variability in the perception of the /m/–/n/ distinction in CV syllables
Authors: Ohde Ralph N. , Haley Katarina
Published: October 2005

In order to determine the efficacy of a pre-identification task designed to assess the range of perceptual cues in normal speakers, adults rated CV syllables produced by children and adults consisting of either /m/ or /n/ in the context of four vowels /i æ u ɑ /. Based on the pre-identification rating task, the syllables of three speakers for each age level of 3, 5, 7, adult female, and adult male representing the entire range of perceptual variation were modified according to several waveform editing techniques. Ten adults identified the place of articulation of the nasal from several murmur and vowel transition segments. The results of the pre-identification rating task revealed that interspeaker variability was greatest for the 3-year-olds and least for the adult females. The findings for the perception of speech segments will be discussed relative to: (1) the development role of interspeaker variability in processing cues to place of articulation, and (2)previous results on the nature of segmental, coarticulatory, and integrated cues in speech development (Ohde, submitted). [Work supported by NIH, DC 00464.]
The influence of presentation level and relative amplitude on the perception of place of articulation of stop consonants in normal hearing and hearing-impaired listeners
Authors: Hedrick Mark , Schulte Laura
Published: October 2005

Previous studies of the /p/–/t/ stop consonant contrast for normal hearing listeners have shown that both manipulation of the amplitude of the burst relative to the vowel in the F4–F5 frequency region and overall presentation level can influence the perception of place of articulation [Ohde and Stevens, J. Acoust. Soc. Am. 74, 706–714 (1983); Gravel and Ohde, Asha 25(10), 101 (1983)]. The influence of relative amplitude and presentation level was tested for both normal-hearing and hearing-impaired listeners in the present study. Synthetic CV stimuli were employed, and the amplitude of the burst relative to vowel onset amplitude in the F4–F5 frequency region was manipulated across a 20-dB range. The findings revealed a difference in the perception of place of articulation between the two subject groups as a function of presentation level. The results are consistent with the premise that abnormal response growth near threshold may alter consonant perception in the hearing impaired. [Work supported by NIH.]
The influence of sentence articulation rate on the internal structure of phonetic categories
Authors: Wayland Sarah C. , Miller Joanne L. , Volaitis Lydia E.
Published: October 2005

Numerous experiments have shown that listeners perceive phonetic distinctions in a rate-dependent manner. A case in point is the /b/–/p/ voicing distinction, specified by voice onset time (VOT). One standard rate effect is a shift in the/b/–/p/ boundary toward longer VOT values as speech becomes slower. Both a slowing of the target syllable itself and a slowing of the sentence containing the target syllable produce the effect. A recent investigation [J. L. Miller and L. E. Volaitis, Percept. Psychophys. 46, 505–512 (1989)] demonstrated that when speaking rate is specified by the target syllable, it alters not only the location of the category boundary, but also which stimuli within a category are judged to be the best exemplars of that category. In the present investigation, it was asked whether the rate at which a sentence is articulated can have the same comprehensive effect. A series of 215-ms syllables were created that ranged from /bi/ through /pi/ to a breathy, exaggerated version of /pi/; VOT varied from 10 to 205 ms. Each syllable was inserted into a fast and slow version of the sentence frame ‘‘She said she heard −− here.’’ A preliminary two-choice study (with VOT values between 0 and 60 ms), confirmed the standard effect of sentence rate at the /b/–/p/ category boundary. In the main experiment, listeners heard sentences of the same rate in random order. They rated each target syllable for its goodness as /pi/ on a scale of 1 to 10; the higher the number, the better the exemplar. It was expected that for each sentence rate, only a limited range of target stimuli would be given high ratings. At issue was the location of this range of best exemplars.

If sentence rate, like target syllable rate, alters the internal structure of the category, then as the sentence becomes slower, the best-exemplar range should shift toward longer VOT values. This is precisely what happened. This finding underscores the comprehensive nature of the listener’s adjustment for speaking rate during phonetic perception. [Work supported by NIH.]
Pragmatic and semantic contextual effects on the phonological rule of flapping
Authors: Charles-Luce Jan , Lewin Betina , Ragonese Elvira
Published: October 2005

Previous studies have investigated the phonological rule of intervocalic flapping. Whereas acoustic measurements have shown that flapping does not always result in homophones, the interesting question is why flapping may or may not occur. The current investigation of flapping examines the role of a listener’s presence versus absence and the role of semantic context in the application of flapping. Subjects produced such words as writer and rider in two types of passages. In one passage type the semantic context biased the meaning of the target word. In the other passage type, the semantic context was neutral as to the meaning of the target word. One group of subjects produced these passages when a listener was present in the recording room. They were instructed to produce the passages explicitly for the sake of the listener. The other group of subjects produced the passages when alone in the room. The results show that passage type does affect the rule of flapping. Underlying voicing is distinguished in neutral contexts but not in the biasing contexts. Moreover, the voicing distinction is significantly greater in the listener present condition but smaller and not significantly different in the listener absent condition. [Work supported by NIH Grant No. DC00879-01 and NIH Grant No. DC00957-01.]
Sound radiation from a fluid-loaded finite cylinder as a function of spacing between forcing pulses
Authors: Mann J. Adin , Kruger Daniel H.
Published: October 2005

Sound radiation from a spherically endcapped, point-driven, fluid-loaded, cylindrical shell will be presented in the time domain. The impulse response functions that are measured with near-field acoustical holography are used to simulate the response to a synthetic driving force with two pulses. The individual signals are Gaussian-windowed single-frequency pulses. As the time spacing between pulses changes, the amount of energy radiated by the shell varies greatly−from less than to greater than the energy radiated by a single pulse. These variations are explained with a frequency domain model and by the average energy radiated from different points on the shell. One can dissipate the mechanical energy input to the shell by the force driver either through sound radiation or by damping in the shell. Thus these results show that it is possible to force more energy to be damped in the shell and to reduce the amount of sound energy radiated to the far field. These observations cannot be made when analysis is confined to the frequency domain.
Instantaneous fluid–structure interaction resulting from a point-driven, fluid-loaded, cylindrical shell
Authors: Romano Anthony J. , Russon Kevin L. , Williams Earl G. , Schuette Lawrence C.
Published: October 2005

A formulation for the structural intensity in a thin, point-driven cylindrical shell is presented, as well as the corresponding energy balance relationships. These representations are then applied to real, experimental data for the presentation and analysis of fluid–structure interaction. A movie will be presented that displays, simultaneously, the instantaneous structural intensity within the cylindrical shell, as well as the instantaneous intensity in the surrounding fluid due to a transient pulse delivered by the point driver. The contributions of the individual components comprising the formal representation of the structural intensity (i.e., longitudinal, in-plane shear, etc.), as well as the mechanism of fluid–structure interaction in the very near field, will be discussed in detail from the point of view of instantaneous energy flow.
Fluid–structure interaction studies: Scattering from simple submerged shells using scattering holography
Authors: Williams Earl G.
Published: October 2005

Recently developed at NRL, scattering holography provides the surface velocity at thousands of points on shells excited by an external plane wave. This measurement capability allows for detailed studies of the mechanisms of scattering at the surface of finite cylindrical shells. Time-domain wave-vector filtering is applied to data from a simple shell above a ka of 2.0 in order to study the interaction between the surface and the fluid. In particular, regions of the surface that act as secondary sources, scattering to the far field, are identified using supersonic imaging techniques. Also, results show the generation of subsonic waves on the shell, along with the expected supersonic trace-matched waves. The regions where the fluid and structure interact to produce these subsonic waves will be discussed, along with details of wave propagation on the shell. [Work supported by ONR.]
The spatial and temporal response of fluid-loaded, line-driven panel structures
Authors: Wahl T. J. , Bolton J. S.
Published: October 2005

In this paper wave propagation is considered in and near fluid-loaded, line-driven panel structures in several configurations. In one configuration, for example, the driven panel is separated from a second panel by a finite-depth, fluid-filled space. In a second case, wave propagation in fluid-loaded, ribbed panels is considered. In both those cases, solutions for the spatial and temporal distributions of the panel velocity as well as the acoustic particle velocity and sound pressure in the adjacent fluid can be obtained by using wave-number transform techniques. The inversion integral that defines the spatial response in the frequency domain may then be evaluated by using the fast Fourier transform algorithm. Subsequently, the temporal response may be obtained by performing an additional inverse Fourier transform. Having obtained the pressure and velocity solutions it is a straightforward matter to compute both the instantaneous and time-averaged intensity in the fluid adjacent to the structure. By examining the latter quantities the flow of acoustic energy from the radiating structure to the fluid and viceversa may easily be visualized. Examples will be given in which energy is shared between the driven panel and a number of different modes in the adjacent fluid space, and the existence of multiple coincidence frequencies in that case will be illustrated. In addition, conversion of subsonic panel wave motion into radiating components at line discontinuities will be considered.
Prediction of noise in industrial workrooms
Authors: Hodgson Murray
Published: October 2005

This paper reviews the state of the art of noise (steady-state sound-pressure level and reverberation time) prediction in industrial workrooms. First, some experimental results are presented to illustrate typical workroom noise characteristics. The room-acoustical parameters that must be included in a comprehensive prediction model are discussed. Available theoretical prediction approaches (diffuse-field theory, method of images, ray tracing, simplified models), with their associated advantages and disadvantages, are reviewed. Ray tracing, the most comprehensive approach, is described in some detail. The results of on-going work aimed at determining applicable values of the input prediction parameters (surface and furnishing absorption coefficients and furnishing densities) are discussed. The main problems associated with workroom noise prediction are summarized. Finally, two case studies, one involving comparing measured and predicted noise levels in a power generating station and another involving predicting the effectiveness of noise-control treatments in a workshop, are presented.
Hearing conservation on explosives and small arms training ranges
Authors: Sachs Felix Z. , Corbin William W.
Published: October 2005

The OSHA regulations for hearing conservation are very detailed for exposures to steady-state noise. Application of hearing conservation elements to explosives and outdoor small arms training ranges requires a somewhat different emphasis, particularly in the areas of impulse noise criteria, noise hazard identification, hearing protection, administrative controls, and engineering controls. These differences are discussed using specific examples of an outdoor rifle range and an explosives training range. The applicability and nonapplicability of noise dosimetry is also discussed. The dosimetry issue arose after contact with the local OSHA compliance office indicated that noise dosimetry may be required by an inspector. Impulse noise measurements, 140-dBP contours for various explosives training charges, and dosimetry results are provided.
Numerical simulation of interface waves by high-order spectral modeling techniques
Authors: Seriani Geza , Carcione Jose M. , Priolo Enrico
Published: October 2005

This work presents two different approaches for simulating interface waves in elastic media. The techniques are both based on a Chebychev expansion of the wave field. The first algorithm solves the elastodynamic equations in differential form by computing the spatial derivatives with the Chebychev pseudospectral method. The second algorithm uses the Chebychev polynomials as an interpolant base in a variational formulation, and is called the spectral element method. Both techniques, in particular the second, posses spectral accuracy and are suitable for treating interface problems for which boundary conditions and arbitrary interface geometries are naturally taken into account. The reason for using two different approaches is the crossvalidation of the results. Most wave propagation problems have no analytical solution, and if two different techniques give the same solution, one is sure that this solution is free of numerical artifacts. The first example compares numerical and analytical solutions of Rayleigh waves propagating along the surface of an homogeneous half-space. This test confirms the accuracy of the numerical algorithms. The second example has no analytical solution and compares the numerical results of a Stoneley wave generated by a Rayleigh wave at a vertical interface touching the surface. [Work supported by EEC.]
Noise radiation from ducted fans with realistic duct-rotor coupling
Authors: Farassat F. , Spence P. L.
Published: October 2005

The problem of noise radiation from inlet and exhaust of ducted fans is important because of anticipated stringent noise standards. The aerodynamic and duct propagation problems of these engines have been solved. What is needed is the coupling of rotor aerodynamics and duct propagation using realistic physical and geometrical models on today’s high-speed computers. In this paper, a method is presented for prediction of noise from the inlet of ducted fans correctly accounting for fan blade aerodynamics. An Euler code is used giving the fluid dynamic parameters such as pressure and velocity at a duct section approximately one chord length from the fan face. Here, all of the pressure disturbance is propagating. This pressure disturbance is decomposed into spinning modes using Fourier and Hankel transforms in circumferential and radial directions, respectively. The amplitude of each mode is produced from interaction of upstream and downstream (due to reflections from the inlet) moving waves. The relative amplitudes of these waves are computed using a duct propagation code based on FEM by initializing the upstream moving wave of a given mode to unit amplitude and finding the reflection coefficients of all modes. A system of linear simultaneous equations for amplitudes of upstream and downstream moving waves is constructed and solved. From these amplitudes, the radiation from the duct inlet can be calculated. Computed examples of radiation from ducted fans in forward flight are presented.
The software required for the computer generation of virtual environments
Authors: Zyda Michael J.
Published: October 2005

The initial phase of virtual-world development has focused on novel hardware and ‘‘cool’’ graphics demonstrations. The current phase is focusing on the software bed underlying ‘‘real’’ applications. The focus of this talk will be on the software required to support large scale, networked, multiparty virtual environments. Topics to be discussed include (1) navigation (virtual camera view-point control and its coupling to real-time, hidden-surface elimination); (2) interaction (software for constructing a dialogue from the inputs read from our devices and for applying that dialogue to display changes); (3) communication (software for passing changes in the world model to other players on the network, and software for allowing the entry of previously undescribed players into the system); (4) autonomy (software for playing autonomous agents in our virtual world against interactive players); and (5) scripting (software for recording, playing back, and multitracking previous play against live or autonomous players, with autonomy provided for departures from the recorded script). All of this software is needed to provide a fully detailed, fully interactive, seamless virtual environment.
Dimensions of synthetic experience
Authors: Robinett Warren
Published: October 2005

A taxonomy is proposed to classify all varieties of technologically mediated experience. This includes virtual reality and teleoperation, and also earlier devices such as the microscope and telephone. The model of mediated interaction assumes a sensor-display link from the world to the human, and an action-actuator link going back from the human to the world, with the mediating technology transforming the transmitted experience in some way. The taxonomy is used to classify a number of example systems. The long-term prospects of this field are then speculated upon, ignoring constraints of cost, effort, or time to develop. Finally, the ultimate limits of synthetic experience are discussed, which derive from properties of the physical universe and the human neural apparatus.
Selective implementation of the sector-focusing matched-field processor for improved robustness in a mismatched shallow-water environment
Authors: Chandler H. A. , Feuillade C. , Smith G. B.
Published: October 2005

In matched-field processing (MFP) inaccurate or incomplete knowledge of the environmental and system parameters required for the propagation model (referred to as modeling ‘‘mismatch’’) can lead to degradation or loss of the signal peak, and predicted estimates of the source parameters which are at wide variance with the truth. Much recent work in MFP has been concerned with the development and investigation of algorithms which provide improved stability in the presence of environmental mismatch and other modeling errors. In this study, the performance of various implementation strategies of the sector-focusing algorithm (SF) for application to a mismatched shallow-water environment is investigated. The SNAP propagation model was used to generate the replica acoustic pressure field for the water channel with a depth variable sound-speed profile. It was also used to simulate a ‘‘detected’’ field due to an acoustic source in the presence of modal noise. These were then correlated using the algorithm for selected degrees of mismatch of the water sound-speed profile. SF allows considerable flexibility in its mode of implementation. The method under investigation here employs the use of a ‘‘sliding’’ sector that contains the replica of the search point as well as those of the surrounding points. Simulation results indicate that this SF technique is highly robust against mismatch and that the sector size, shape, and dimensionality required to give optimal performance of the algorithm, for a specific degree of mismatch, is dependent upon the location of the search point within the waveguide.

Numerical studies have been performed and results will be presented. [This work was supported by the Office of Naval Research, Program Element 61153N, with technical management provided by the Naval Res. Lab., Stennis Space Center, MS.]
A scheme for measuring environmental parameters from the ambient acoustic field with a vertical array of hydrophones
Authors: Smith George B. , Byrne Charles L. , Chandler Howard A.
Published: October 2005

High-resolution matched-field processing requires rather exact specification of the environment through which the acoustic field has propagated in order to perform satisfactorily. Measuring the environment to this level of precision presents a severe challenge to the implementation of high-resolution matched-field algorithms. Hence, techniques that can extract environmental information from the ambient acoustic field make a desirable complement to the high-resolution source localization techniques that require such a well-specified environment. In this work, a high-resolution estimator function that matches ambient acoustic field data from a vertical array of hydrophones to trial environments from a normal mode environmental model is used to estimate the parameters of the environment through which the acoustic energy passed. Shallow-water simulations are used to explore the response of the estimator as a function of several environmental parameters. The general conclusion is that unique estimates for these parameters exist, and the estimator developed here is sensitive to small changes in these parameters. [This work was supported by the Office of Naval Research, Program Element 61153N, with technical management provided by the Naval Research Laboratory, Stennis Space Center, MS.]
Considerations in the resampling of digital audio signals
Authors: Smith Julius O.
Published: October 2005

The ‘‘digital audio revolution’’ has made it possible to routinely analyze and process acoustic signals entirely in the ‘‘digital domain.’’ In this domain, some conceptually simple operations, such as ‘‘speeding up’’ or ‘‘slowing down’’ the playback of a sound are no longer so simple; one can no longer merely change the speed of the tape-drive mechanism. Since the sampling rate in a D/A converter is usually not variable in a general way, changing the playback speed requires resampling the stream of numbers that represent the signal, or samplingrateconversion. Sampling-rate conversion is a special case of the problem of evaluating a sampled signal at an arbitrary time. The easiest algorithm, analogous to a sample-and-hold circuit, is to simply take the sample nearest the desired sample time. A much higher quality algorithm, costing two additions and one multiply per sample, is to linearlyinterpolate using the two samples on either side of the desired sample time. Doing it ‘‘really right’’ requires bandlimitedinterpolation which is implemented by convolving the signal samples with a sin(x)/x function translated to the desired sample time and sampled at the signal’s sampling instants. The cost is of course an infinity of multiplies and adds per sample of output, so this is not possible in practice. This presentation will describe practical algorithms for sampling-rate conversion and discuss some of the tradeoffs involved.
The algorithmic sampler: An analysis problem?
Authors: Arfib D. , Guillemain Ph. , Kronland-Martinet R.
Published: October 2005

To play natural sounds on an algorithmic synthesizer, it would be necessary to extract parameters that correspond to a synthesis model from an analysis of a real sound. The aim of this lecture is to show different facets of a time-frequency representation that are very particular in the signal-processing field because they are oriented toward the musical use. For example, psychoacoustic criteria allow one to ‘‘get rid of’’ the incertainty principle on time and frequency. Here, only the acoustically relevant parameters are looked for rather than the exact physical data. For that purpose, time-frequency transforms were used, namely the Gabor and the wavelet transforms, and additional work on the time-frequency representations they provide was conducted. For example, the spectral line estimation allows one to separate each elementary component and to estimate the modulation law associated to each one by solving a linear system where the coefficients come from the representation. Special features concerning the sound can be derived from ridges extracted from the phase diagram; this can lead to the estimation of frequency modulation laws in a FM model. The evolution of the centroid of the spectrum can be a good indicator for a synthesis using a wave-shaping model. The lecture will be accompanied by a lot of time-frequency representations showing the importance of the choice of the parameters of the analysis, and the diagrams that one can derivate from them. It will also be accompanied by sound examples.
Classical approaches to predicting industrial noise
Authors: Brittain Frank H.
Published: October 2005

Predicting operational noise levels is an essential part of designing an industrial facility. Community noise levels are usually predicted for environmental assessment and licensing. In-plant noise levels are predicted, both to evaluate occupational noise exposure and as an input to modeling of community noise predictions. Predictions are used to evaluate the effect of various combinations of low-noise equipment and add-on noise controls. Prediction are also used to evaluate the effects of different operating and atmospheric conditions. This paper shows how a noise model can be structured, and then modified in an iterative process of developing a practical and cost effective approach to noise control. Alternate approaches to performing the necessary calculations on a computer are reviewed. This paper describes various classical techniques for estimating source strength and directivity, indoor and outdoor propagation, as well as the noise reduction of prospective noise controls. Some limitations of these classical techniques are identified.
The production and perception of categorical patterns in the relative-timing aspects of speech
Authors: Boucher V. J.
Published: October 2005

The object was to isolate, across changes in speaking rate, categorical patterns in the relative timing of aspects that can relate to voicing distinctions. In a first series of observations, French sujects were asked to produce sequences [tapetape...] and [dapedape...] at different rates. Categorical ratios were observed in the timing of releases and closures when these were measured with reference to a CVC or CV interval but not with reference to VC. Only the ratios of release times were categorical for all subjects and CVC was more successful in revealing categorical ratios. Second, to determine if CVC provides a reference frame in perception, a test was constructed from multisyllabic sequences containing a voicing distinction [t]/[d]: [apapatapapa]/[apapadapapa]. Thirty milliseconds was spliced away from various portions of the sequence containing [d] and the results of an ABX test showed that perception shifted markedly from [d] to [t] when the 30-ms splice was applied to both the C and V surrounding [d] but not when the splicing occurred one syllable away or when it was applied to either the C or V surrounding [d]. This suggests that perception and production of categorical patterns in timing aspects operates by reference to CVC.
Matched-field processing in a randomly time-variant propagation environment
Authors: Preisig James C.
Published: October 2005

Uncertainty in the characteristics of the propagation environment and the resulting processor mismatch can lead to a significant degradation in the performance of adaptive matched-field processors. Most previously proposed techniques for dealing with environmental uncertainty model the environment as being underspread (i.e., the environment can be assumed to be constant over the observation interval of the processor). However, in some scenarios there are both underspread and overspread components to the environmental fluctuations. An adaptive matched-field processor is proposed that separates the environmental fluctuations into overspread and underspread components and handles the two types of variability in fundamentally different ways. The processor simultaneously optimizes its worse-case performance evaluated over the range of underspread environmental conditions and its average performance evaluated over the range of overspread environmental conditions.
Robust matched-field matched filters
Authors: Gingras Donald F. , Gerr Neil L.
Published: October 2005

The incorporation of propagation modeling into array signal processing, usually referred to as matched-field processing, has been shown to provide accurate source localization information in many situations. It is well known though that the performance of these methods is quite sensitive to uncertainty about knowledge of the environmental parameters. In this paper, broadband matched-field processing methods that are tolerant of the uncertainty about environmental knowledge are investigated. A ‘‘robust’’ matched-field matched-filter processor based on minimax robust filtering methods is developed. The performance of the robust processor, in the presence of uncertain environmental knowledge, is compared with conventional methods. In the context of a shallow-water example, with uncertain knowledge about the sound-speed profile, the minimax robust processor is shown to provide a considerable improvement in performance with respect to conventional nonrobust methods (i.e., reduced error in source location estimate and increased source peak-to-sidelobe ratio).
Adaptive matched-field processing for noise or clutter rejection in the presence of mismatch
Authors: Lee Yung P. , Freese Herbert A. , Hanna John S. , Mikhalevsky Peter N.
Published: October 2005

Capon’s maximum-likelihood method (MLM) has been used in many areas of signal processing, but it is known to be sensitive to mismatch. Several robust algorithms, such as the white noise constrained method and the ‘‘reduced’’ MLM, have been developed to reduce the sensitivity to mismatch. The objective of all techniques is to obtain an accurate measure of the energy originating in a specific resolution cell, whether this energy be considered signal or noise. In this paper, simulation results are presented for various adaptive matched-field processing methods used in conjunction with a tiltedlinearray which have applications to both active and passive systems. In the simulations, the noise is modeled as having two components, one continuous, and the other discrete. The clutter is modeled as backscatter arising from many randomly distributed discrete sources. It is shown that adaptive matched-field processing, even with mismatch present, can provide significant suppression of both noise and reverberation in certain resolution cells, while at the same time maintaining almost unity gain for these cells.
EXOS research on the design of haptic interface and force reflective controller
Authors: An Bin , Eberman Brian
Published: October 2005

EXOS had developed two state-of-the-art prototype master controllers for controlling robot hand and manipulators under the Small Business Innovation Research (SBIR) program with NASA. One of such devices is a two degree-of-freedom (DOF) sensory and force reflecting exoskeleton (SAFiRE) which is worn on the hand of a human operator. It measures the movement of the human finger and reflects the interaction forces between the slave robot hand and the environment back to the human finger. The second device is a position sensing Exoskeleton ArmMasterTM (EAM) that is worn on the human operator’s arm. This device simultaneously tracks the motions of the operator’s three DOF shoulder and two DOF elbow. Both of these devices are currently controlling robots at NASA. Currently, a five-fingered SAFiRE and a force reflecting EAM are being developed under two phase II NASA SBIR grants. This paper will include discussion of: (1) the design of the current prototypes, (2) phase II project objectives, (3) human haptic interface design issues that must be addressed, (4) progress to date in addressing these issues.
Acoustic radiation from a multilayer sandwich plate subjected to a point-harmonic excitation
Authors: Kim M. , Hwang Y. F.
Published: October 2005

An exact mathematical formalism was developed to calculate the acoustic response of a fluid-loaded, multilayer, sandwich plate subjected to a point-harmonic excitation. The plate can be fluid loaded on each side with arbitrary acoustic media. The solution was verified with asymptotic solution of a fluid-loaded thin steel plate. Numerical examples are presented for the acoustic radiation into water from various plate configurations subjected to a point force acting on its dry (air) side. The plate configurations considered are: (1) a two-layer elastic/viscoelastic plate, (2) a three-layer symmetric elastic/viscoelastic/elastic sandwich plate, and (3) a three-layer nonsymmetric elastic/viscoelastic/elastic sandwich plate with the viscoelastic layer given a range of different material properties (elastic constants, damping) and thicknesses. To elucidate the radiation mechanisms, the behavior of the modes of wave propagation in the plate is discussed. [Work supported by ONR.]
Prediction of acoustic radiation using analytical/numerical matching
Authors: Bliss Donald B. , Peretti Linda F.
Published: October 2005

Analytical numerical matching (ANM) is a hybrid method that forms a composite solution by combining a low-resolution global numerical solution, a high-resolution local solution, and a matching solution. ANM is a novel method to obtain accurate numerical solutions with high spatial resolution for low computational cost. ANM has been successfully applied to a variety of problems in aerodynamics and vortex dynamics, and is now being applied to problems in acoustics and structural dynamics. The present work illustrates the application of ANM to acoustic radiation. A vibrating surface with sharp discontinuities is placed at the end of a channel. The problem is solved approximately using ANM and compared to the exact solution. In the ANM approach, the sharp discontinuity is intentionally smeared for the global solution, which can then be calculated by efficient low-resolution means. The effect of the discontinuity is handled by the high-resolution local solution, which is solved independently of the geometry of the global problem. The results show the ANM approach to be accurate and dramatically more efficient. Extensions of ANM to more general problems in structural acoustics with sharp discontinuities are discussed. [Work supported by ONR.]
Nonlinear vibration and radiation from a panel-stringer structure near a supersonic jet
Authors: Maestrello L.
Published: October 2005

The experiment was undertaken to enhance understanding of nonlinear response and radiation involving random convective loading. Results presented show broadband nonlinearity of the vibration and acoustic radiation from a panel-stringer structure excited by a supersonic jet near field. The transmitted pressure field radiated from the structure is nonlinear, showing period doubling as well as chaotic behavior, and similarly for the strain response of the panel vibration. The radiation field also contains shocks and the formation of harmonics whose amplitude relative to that of the fundamental increases with distance. These results support the view that transient chaotic responses of the panels occur randomly.
Wigner function description of fluid-loaded plates
Authors: McCoy John J. , Dimitriadis Emilios K.
Published: October 2005

At a previous ASA meeting, a Wigner function description was presented of the spatially limited, narrow-band (in time) forcing of a fluid-loaded elastic plate and the radiation of sound therefrom. The formulation demonstrated that the complete experiment consists of a sequence of independent propagation/scattering events, each described by an operator that can be termed a propagator (in position coordinate)/filter (in Fourier coordinate). The intended application envisioned a stochastic forcing; e.g., at a turbulent boundary layer; but the framework is not so limited. In this presentation, a number of theoretical and numerical results are shown from a detailed study of this formulation. Several issues are addressed. Thus the propagator/filter for describing the process that transforms the Wigner function defined on the forcing to that defined on the plate deflection, is seen to be highly structured, difficult to interpret or numerically capture. This high degree of structure can be eliminated and an intuitive result obtained under two conditions: The propagator/filter is applied to a ‘‘typical’’ stochastic forcing to give the plate deflection Wigner function for the intended application. Or, a second operator that describes the effects of a linear phased array on the level of the Wigner function is applied to the propagator/filter. A number (3) of associated propagator/filters is then developed such that when viewed through the output of phased arrays tuned to respond to a particular Fourier component, approximate the output of the exact propagator/filter. These associated operators are given simple analytic expression; are intuitive; and, describe the contributions due to poles with small imaginary components, branch points, and what is left. Finally, expressions are derived for estimating the outputs of linear arrays of hydrophones located in planes at any distance from the plate.
Analysis of the pass–stop band structure of a membrane with uniformly spaced structural discontinuities
Authors: Pierucci Mauro , Carr Brian
Published: October 2005

An elastic structure with a series of uniformly spaced structural discontinuities is known to have a unique pass–stop band in the wave-number space. In this paper, an infinite membrane, the simplest type of elastic structure, is selected. The uniformly spaced structural discontinuities are chosen to be composed of a mass-spring system. The solution in wave-number space can be written in closed form. The pass–stop band structure when viewed in the wave number versus kl space resembles a floor tile appearance. The tile appearance is periodic when viewed in the constant k plane, but has a nonperiodic pattern if viewed in the constant l plane. The relative magnitudes of the different bands are presented. If the evenly spaced inhomogeneity is masslike, then the pass-band structure will start with a pass-band at low values of kl. If the inhomogeneity is springlike, then the first band will be a stop band. For a structural inhomogeneity that has a mass–spring behavior, the pass–stop band acquires a more complex structure with a pass-band window of much larger than expected width at the natural vibration conditions of the inhomogeneity.
Vibration analysis of a thick plate using 3-D elasticity equations
Authors: Padiyar Satish , Cuschieri J. M.
Published: October 2005

Dynamic analysis of thick-plate structures are typically performed using the approaches of Mindlin [J. Appl. Mech. 18, 31–38 (1951)] for out-of-plane waves, and Mindlin and Medick [J. Appl. Mech. 26, 561–569 (1959)] for in-plane waves. Using this type of analysis, approximations are included to simplify the approach. The solution for the response of the thick plate is obtained for the mid-plane of the plate. The response away from the mid-plane is then based on an assumed set of orthogonal functions. With this formulation, the in-plane and out-of-plane wave equations become uncoupled. One set of equations is obtained that describes the in-plane wave motion and another set of equations is obtained which describes the out-of-plane wave motion. An alternative approach to study the behavior of a thick plate, is to use the full set of the three-dimensional elasticity equations. This approach can lead to a complex mathematical formulation even for such a simple structure as a plate with all edges stress free. A solution for the free vibrations of a linearly elastic rectangular slab with stress-free boundaries using the three-dimensional stress equations has been developed by Hutchinson and Zillmer [J. Appl. Mech. 50(3), 123–130 (1983)]. In this case, the solution includes all the possible wave types. A solution for the forced vibration of a plate using an approach based on the method of Hutchinson and Zillmer is obtained, and compared to the solution for the same plate obtained using the Mindlin approaches. The differences and similarities between the two methods and the corresponding results are investigated. The response obtained by either of the two techniques can be used to analyze the scattering of wave energy from one wave type to another in the presence of discontinuities. [Work sponsored by ONR.]
Duration of the acoustic components of infrequent and frequent words
Authors: Whalen D. H.
Published: October 2005

In a study reported at a previous meeting of the Society, subjects produced longer durations when reading lists of infrequent words than ones with frequent words. This was in spite of the fact that the words contained exactly the same phonemes by virtue of being homophones (e.g., ‘‘right’’ and ‘‘rite’’). The present report examines those differences more closely. Each major acoustic component of a word was measured. The consonantal segments included (1) the fricative noise of fricatives, (2) the resonance of nasals, liquids, and glides, and (3) a single measure for stops that included closure, burst, and aspiration. Vocalic segments were also measured. The results show that the duration for the components of infrequent words were all longer than those for frequent words, mirroring the results for overall duration. Expressed as a percentage of the total duration, though, only resonants in syllable onsets showed any difference due to frequency. Thus, in general, the duration differences resemble interspeaker, habitual rate differences more than they do effects of lexical stress or intraspeaker rate changes. These results suggest that the pattern of intraword coordination is similar for high- and low-frequency words, and that the duration differences are the result of the production process itself. [Work supported by NIH Grant DC-00825.]
The relation between compensatory shortening and speech task
Authors: Bell-Berti F. , Zaremba R.
Published: October 2005

Compensatory shortening has been reported to occur with increased utterance complexity; for example, durations of segments decrease as the number of syllables in a phrase increases. But compensatory shortening is not always found, and it has been suggested that its occurrence is related to differences in the nature of the speech tasks required of a speaker, for example, producing citation-form speech and oral reading [T. H. Crystal and A. S. House, J. Acoust. Soc. Am. 88, 101–112 (1990)], and may also vary with the language studied. The origin of this timing pattern (or its absence) is of particular interest in understanding speech production, as a reflection of planning unit size; if its presence varies with speech task, so must the planning unit. This paper reports results of a study of several speech tasks (list reading, repeating a recorded exemplar, paragraph reading) on the extent of compensatory shortening. [Work supported by St. John’s University and NIH DC-00121 to Haskins Laboratories.]
Timing characteristics of syllables in Standard Italian: Geminate versus nongeminate consonants
Authors: Brighenti Laura , Homel Peter
Published: October 2005

The nature of the Italian geminate consonant has long been a matter of debate for researchers. Past studies have variously characterized it, in contrast to the nongeminate consonant, as being either: (1) longer in duration; (2) more tense, or reinforced (as opposed to lax); or (3) that it was actually a bisyllabic, or geminate cluster, that is, a sequence of two identical phonemes across contiguous syllables. This paper presents an analysis of geminate versus nongeminate consonant duration in samples of running speech obtained from a native speaker of Standard Italian. The results seem to indicate that, although the geminate syllable is generally longer than the nongeminate, its perceptual characteristics cannot be systematically attributed to any single factor alone, but are actually a function of several acoustic elements operating at the same time. In particular, both closure time and vowel length appear to play a key role in distinguishing geminate from nongeminate syllables.
Design of haptic interfaces
Authors: Salisbury J. K.
Published: October 2005

One of the key activities in telerobotic and emerging virtual environment systems is mechanical interaction with objects. In normal human experience, mechanical (or haptic) interaction is one of the most expressive ways in which one can effect changes in the environment. How one can and should build suitable haptic interfaces (gloves, joysticks, exo-skeletons, etc.) is currently a subject of intense research throughout the world. Given that haptic interface design is severely limited by available technology, critical choices between complexity and performance must be made. Ultimately these choices must be made with knowledge of task complexity and the required fidelity of display. This presentation will review the current state of haptic interface technology, attempt to classify the important performance attributes, and try to give a sense of the design challenges which lie ahead.
Digital feedback suppression in open-ear hearing aids
Authors: Ruppel Timothy H. , Mendel Lisa Lucks , Shields F. Douglas
Published: October 2005

Some preliminary studies into the effectiveness of digital feedback correction schemes for open-ear hearing aids have been conducted. Three different hearing aids were used: (1) a commercially available behind-the-ear (BTE) hearing aid with an open earmold modified so that its internal filters and amplifiers were bypassed and the microphone and receiver connected directly to a digital signal processor, (2) the same BTE hearing aid with a closed earmold for comparison, and (3) a specially designed hearing aid with the microphone placed at the entrance to the ear canal and the receiver placed directly inside the ear canal. Off-line probing was used to determine the characteristics of the feedback path. In this experiment, the subjects had normal hearing. The addition of digital feedback control showed significant improvement in the available insertion gain from the open ear devices, as demonstrated in real ear measurements of the subjects.
Efficiency of analytic versus synthetic listening in spectral pattern discrimination
Authors: Doherty Karen A. , Lutfi Robert A.
Published: October 2005

Experiments on auditory pattern discrimination generally fall into two categories: those that require the listener to selectively attend to a single element of an acoustic pattern (analytic), and those that require the listener to combine information from multiple elements of the pattern (synthetic). In the present study, numerical estimates were made of the relative efficiency of analytic and synthetic listening strategies in a spectral pattern discrimination task. The stimuli were multitone complexes comprised of the six octave frequencies from 250–8000 Hz. In the analytic listening condition, the signal was an increment in the level of one of the six tones (250, 1000, or 4000 Hz in different trial blocks). In the synthetic listening condition, the signal was an increment in the level of all six tones. The levels of the individual tones were also randomly perturbed from trial to trial to permit efficiency estimates of the listening strategies using a COSS analysis [B. G. Berg, J. Acoust. Soc. Am. 88, 149–158 (1990)]. Results from 12 listeners in the 2IFC procedure suggest that analytic listening poses a greater challenge to listeners in spectral pattern discrimination tasks than does synthetic listening. [Work supported by NIDCD.]