bluuebunny/crossref_metadata_2025 huggingface dataset:
Acceleration of integral equation based transient analysis of acoustic scattering phenomena using the plane wave time domain algorithm
Authors: Ergin A. Arif , Shanker Balasubramaniam , Michielssen Eric
Published: July 2002

The numerical analysis of transient scattering from homogeneous bodies residing in an unbounded medium is often performed using integral equation (IE) based methods. The major advantages of these methods over differential equation based techniques are that (i) the radiation condition is implicitly imposed in the formulation, and that (ii) the number of spatial unknowns, Ns, scales as the surface area of the scatterer. However, IE techniques are notoriously costly as their computational complexity scales as O(N2s) per time step. This complexity can be reduced considerably by using the recently introduced plane wave time domain (PWTD) algorithm [A. A. Ergin et al., J. Comput. Phys. 146, 157–180 (1998)]. In this presentation, the PWTD algorithm will be briefly reviewed and its incorporation into an IE-based transient solver for analyzing scattering from rigid bodies will be elucidated. It will be shown that the computational cost of a transient analysis using two-level and multilevel PWTD enhanced solvers scales as O(Ns1.5logNs) and O(Nslog2Ns) per time step, respectively. Numerical examples that validate these complexity estimates and demonstrate the efficacy of the proposed methods in analyzing scattering from realistic structures will be presented.
Animations for teaching more advanced acoustics topics
Authors: Russell Daniel A.
Published: July 2002

Computers and the World Wide Web are quickly replacing traditional methods of presenting animations of acoustic-wave phenomena in the classroom. A previous paper [V. W. Sparrow and D. A. Russell, J. Acoust. Soc. Am. 103, 2987 (1998)] outlined how mathematica could be used to generate animations which can be converted to quicktime movies or animated GIF images for insertion into HTML documents. The mathematical prowess of a program like mathematica allows for animating more complex wave phenomena while ensuring that the physics and mathematics are correct. At the same time, primitive graphical capabilities allow for visually pleasing results. This paper is an extension of previous work and will include a gallery of new animations which have been used in a senior-level acoustics course for engineering and physics majors. Animations will include some theoretical (sound fields of complex sources, particle motion in waves, and multiple-dof vibrating systems) as well as some experimental (modes of vibration of acoustic and electric guitars) animations. Some hints of mathematica tricks to generate animations will be shared, as well as methods for producing animated GIF files.
A multi-media courseware that applies vibration theories to real-world problems
Authors: Raju P. K. , Sankar Chetan
Published: July 2002

Many engineering students lack the breadth of knowledge and skills that are fundamental to the practice of their profession. There is now a growing realization among educators of the need to put a greater emphasis on imparting higher-level cognitive skills. The learning experience must move from lecture as a dominant mode to include a significant level of active learning approaches. In order to fulfill these needs, written case studies were developed and used to bring real-world problems into engineering classrooms. New multi-media information technologies provide access to vast information sources, support safe discovery-based educational experiences, and more aggressively support peer-to-peer education. Studies report that the nonlinear systems associated with multimedia technologies are superior to linear paper-based systems in improving problem solving skills and increasing user satisfaction. Therefore, the written case studies were enhanced by adding video, audio, photographs, and competency material to create a CD-ROM so that the students are provided a rich set of materials that describes a real-world engineering problem involving control of excessive vibration in a power plant. Testing of this CD-ROM in vibration courses has shown that students applied the theories of vibration and rotordynamics in solving this real-world problem. [Work supported by NSF DUE ♯9752353.]
Inverse problem of geologic parameters estimation for vibration calculations in city conditions
Authors: Makhortykh Sergey A. , Rybak Samuil A.
Published: July 2002

In the report a new method of the dynamic and dissipative ground parameters estimation (velocities and damping factors of elastic waves) in various geological conditions for the modern city is presented. Knowledge of the specified parameters is necessary for prediction of vibration levels in the ground and buildings near underground railway lines. The approach is based on handling of a medium response on calibrated vibration action. The character of a signal makes possible a very compact representation in a classical orthogonal functions system (Hermite, Laguerre, etc.). Estimated parameters of a model are three velocities of elastic waves: longitudinal, transversal and surface waves and accordingly three factors of dissipation. The obtained nonlinear task of a system identification based on a known experimental signal is solved by means of each component expansion in a series on the chosen basis functions. For satisfactory evaluation, e.g., of three absorption factors, it is enough to take into account only the first terms of a series (signal envelope). The used approximation allows stable results to be received for much smaller experimental points number than in a case with the traditional exponential representation of a signal.
Is the cochlea a wavelet filterbank?
Authors: Wilson Timothy A.
Published: July 2002

Cochlear place and log-frequency responses are sufficiently similar that frequency-domain measurements are sometimes transformed to place-domain ones, using the cochlear map to relate cochlear place and sinusodial frequency. Such similarity has been attributed to the cochlea’s implementation of a wavelet filterbank. For such a filterbank, place responses at different frequencies are shifted versions of each other, not only for the response magnitude, but also for its phase. According to cochlear macromechanical modeling, however, the cochlear partition velocity at the base leads the stapes velocity by 90 deg, regardless of frequency, which is inconsistent with the place responses at different frequencies being shifted versions of each other. In an alternative formulation, derived from the WKB approximate solution to cochlear dynamic equations, cochlear place and frequency responses are expressed in terms of a prototypical place, not frequency, response. Place responses at different frequencies are scaled shifted versions of the prototype, while frequency responses are derived from the prototype in a more complicated manner. Examples are given for several prototype place response, including a gamma-function envelope with exponential phase.
Perception of the tritone paradox by listeners in Texas: A re-examination of envelope effects
Authors: Chalikia Magdalene H. , Vaid Jyotsna
Published: July 2002

Deutsch (1986, 1987) first reported that when listeners are presented with pairs of octave-complex tones related by a half-octave interval (a tritone), they hear the pattern as descending or ascending, according to an individual pitch class template. Individual pitch class effects were found to be stable across tests that use tones with different spectral envelopes. Repp (1994, 1997) has found envelope effects but, in a recent study, Giangrande (1999) has not. Perception of the tritone pattern can vary with the geographical region in which the listener grew up, even though similarities have been reported between listeners in California and South Florida. These similarities suggest a canonical manner of perceiving the tritone stimuli within the U.S., probably propagated by the media (Ragozzine and Deutsch, 1994). The present study tested the hypothesis that a canonical manner of perceiving the tritone stimuli exists, by presenting tritone tones to listeners who grew up in Texas. The influence of the spectral envelope on the perception of these stimuli was also tested. The results suggest that (a) the overall pattern of responses is different from that of Californians, and (b) there are envelope effects.
Effect of intensity on sensory dissonance
Authors: Iyer Nandini , Aarden Bret , Hoglund Evelyn , Huron David
Published: July 2002

Sensory dissonance is known to be related to the critical band [Greenwood (1961); Plomp and Levelt (1965)]. The maximum dissonance between two pure tones has been estimated to arise when the tones are separated by roughly 40% of a critical band [Greenwood (1991)]. Sensory dissonance disappears when the tones are separated by more than a critical band. Experimental work by Kameoka and Kuriyagawa (1969) has further demonstrated that dissonance judgments are affected by intensity. Since the size of critical bands are known to increase with increasing intensity [Moore and Glasberg (1987)], it follows that listeners should locate maximum dissonance at larger-frequency separations for higher-intensity tones. Similarly, the point at which dissonance disappears should involve larger frequency separation for higher intensity. The results of two experiments are reported where dissonance judgments were explicitly examined in the context of intensity-induced changes in critical bandwidth. In the first experiment, listeners adjusted the frequency of one tone away from a fixed tone to the point of maximum dissonance. In the second experiment, listeners adjusted the tone to the point of just-not-noticeable dissonance. Results will be reported for 10 musician and 10 nonmusician listeners.
Relative weights for three different psychophysical tasks
Authors: Matiasek Matthew R. , Richards Virginia M.
Published: July 2002

Relative weights for two profile analysis and one detection task were estimated. For the profile analysis ‘‘bump’’ task the standard was the sum of N equal-amplitude sinusoidal components ranging in frequency from 200 to 5000 Hz. The signal for this task was an increment in level to the 1000-Hz component of the standard. The number of components N ranged from 4 to 50. For the profile analysis ‘‘down–up’’ task the standard was composed of N equal amplitude tones ranging in frequency from 200 to 5000 Hz. The signal to be detected led to a spectrum that varied down–up...down–up. The detection task used the same standard as the profile analysis down–up task, but the signal to be detected was an added 1000-Hz tone. Comparisons of the relative weights revealed that profile analysis bump and the detection of a tone added to a notched masker rely on similar processing strategies. By contrast it was apparent that auditory processing in the profile analysis down–up task depended on a different strategy than the other two tasks. Finally, rough estimates of the auditory filter bandwidths suggest invariance with regard to task. [Work supported by NIH.]
Numerical and experimental investigations on the isolation of structure-borne sound using rubber mounts
Authors: Bittner Margareta I.
Published: July 2002

Rubber mounts are frequently used for the isolation of structure-borne vibrations in the low-frequency range. However, not much research has been done in the acoustic frequency range. In this essay the sound isolation behavior of rubber mounts is investigated by means of the finite element method. The static preload is described by a nonlinear elastic material model. For dealing with the dynamic behavior, a linear viscoelastic model with frequency-dependent parameters is used. The influence of different material parameters on the transmissibility and on the dynamic stiffness of different resilient elements is examined. The calculations are compared with experimental data. For this a measurement apparatus has been set up based on ISO 10 846. Further on, the interaction between resilient elements and a structure supported on them is investigated. The supported structure is chosen to be a plate made of steel. The plate is not regarded to be rigid. The influence of different mounts on the structure-borne sound of the plate is examined. Additionally, it is researched how the sound isolation changes when eigenfrequencies of the supported plate and of the elastic mounts are approximately the same.
Concurrent design concepts for adaptive structures
Authors: Smith G. Clark , Clark Robert L.
Published: July 2002

For an adaptive structure there are two critical design components: temporal compensation and spatial compensation. The influence of the controller on the sensor signals characterizes the temporal compensation of the adaptive structure and the dynamic coupling of the actuator and sensor through the structure characterizes the spatial compensation. Traditionally, techniques for adaptive structure design have concentrated on one component and considered the other fixed. This work proposes a method of concurrent design for both the temporal and spatial compensation of an adaptive structure. Concurrent design concepts are realized by simultaneously executing controller optimization and spatial optimization routines. The structural acoustic control performance and robustness of an adaptive plate structure is improved significantly with concurrent design. The results show the advantages of concurrent design concepts over traditional methods and the effectiveness of the proposed approach.
Issues relevant to the evaluation of speech intelligibility with cochlear implant recipients
Authors: Hawks John W. , Fourakis Marios S.
Published: July 2002

In a series of experiments aimed at identifying factors that influence speech perception by cochlear implant (CI) users, we are currently investigating the reception and utilization of relevant perceptual information available in monosyllables and steady-state vowels. Normal-hearing subjects and adults fitted with Clarion and Nucleus cochlear implant (CI) devices provided identification responses to both natural and synthetic speech. The first experiment examines intelligibility differences of a standard word identification test (NU-6) recorded in three different contexts by two talkers (male/female): (1) individual words spoken in typical citation format, and the same words excised from a narrative read at (2) a typical rate and (3) a rapid rate. The second experiment demonstrates the potential diagnostic value afforded from mapping the acoustic vowel space using steady-state synthetic tokens. The last experiment explores the effects of harmonic richness and first formant (F1) emphasis on synthetic vowel identification by creating tokens varying only in F0, such that a harmonic of F0 would coincide with the F1 center frequency in (1) a male (harmonically rich) F0 and (2) a female (harmonically sparse) F0 range, and (3) an intermediate F0 which was harmonically noncoincident with F1. [Work supported by OSU Office of Research.]
Application of system identification to ultrasonic waveforms
Authors: Daniels Jeffrey A. , Anderson Michael J. , Anderson Tony J.
Published: July 2002

In the context of NonDestructive Evaluation (NDE), system identification is a process that can be used to extract sample properties from ultrasonic waveforms. Usually, system identification is applied directly to time series data. We describe a novel application of system identification. The process is applied to ultrasonic data in the frequency domain. Some investigators have pointed out that useful information can be obtained from the cepstral analysis of frequency domain data. Our approach further generalizes this practice, to the point that frequency domain data are identically mapped to a linear system, with frequency playing the role of time. We believe that our approach can be used to extract material properties, provide sensitive measures to flaws, return detailed information about flaws, extrapolate the bandwidth of ultrasonic measurements, and provide avenues for data compression.
Multiple scattering in ocean bubble clouds—When one expansion parameter is large
Authors: Henyey Frank S.
Published: July 2002

Foldy constructed a model for collections of scatterers, such as a bubble cloud. He assumed the scatterers were arbitrarily small and placed at random, and that each one scattered isotropically. We are concerned with going beyond his approximate solution of his model. There are two expansion parameters in the multiple-scattering series for Foldy’s model, 4πρf/k2 and kf. The first of these is often large (for the bubble-cloud application), while the second is small. ‘‘Renormalization’’ can be used to handle the large parameter, but also renormalizes the other parameter. The talk will be concerned with the resulting expansion and a related issue, the transition between the low-frequency coherent backscattering and the high-frequency incoherent backscatter.
A theory with application to the scattering of waves from many objects
Authors: Werby M. F.
Published: July 2002

Approximate formulations are available for classical wave scattering from aggregates of objects such as schools of fish, bubbles, rain drops, etc. Exact theories exist for two and three objects while scattering from many objects built upon that scheme has been difficult to develop. Other approximations describe the process in terms of an effective propagating wave number. Here a method is proposed that correctly accounts for scattering from an arbitrary number of targets in terms of a matrix expansion that allows for the isolation of the mean field of the scatters and effects from two, three, on to N−1 correlations for N objects. This matrix series is convergent and uses single-particle t-matrices. This leads to terms that correspond to manifest physical processes, each less dominant than the previous term. This allows for truncation based on physical intuition. Further, at any level of truncation the scattering matrix that governs the entire process satisfies symmetry. This method may be reduced to some standard approximations by various limiting procedures. [Work supported by the Office of Naval Research and Naval Research Laboratory.]
Anderson localization in coupled reverberation rooms
Authors: Weaver Richard L. , Lobkis Oleg , Rozhkov Igor
Published: July 2002

It is argued that two undamped reverberation rooms subject to a transient source acting in the first of the rooms, if sufficiently weakly coupled, fail to achieve equipartition, regardless of the amount of time allowed. The critical parameter governing this localization is the ratio of coupling strength (as quantified by the rate at which energy initially leaks from one room to the other) to the modal density. Theoretical estimates for the time evolution of the small amounts of energy that do get transmitted are found to indicate that the energy in room 2 asymptotes at a level proportional to the square root of this ratio. Surprisingly, it is also found that the amount of energy in room 2 overshoots its asymptotic level by 5%–17%. The theoretical predictions are corroborated by numerical simulations of coupled two-dimensional rooms. Laboratory demonstrations, using ultrasonics in coupled elastic bodies, are also presented.
Noisy screams of macaques may function to annoy conspecifics
Authors: Kitko Rachel , Gesser Daniel , Owren Michael J.
Published: July 2002

It has been proposed that noisy screams produced by immature rhesus macaques are used as referential calls for help during conflicts with higher-ranking opponents and requisitely are structurally robust communicators of individual identity [Gouzoules et al., 1984, Anim. Behav. 32, 182–193 (1984)]. However, as recent data indicate that these sounds are not individually distinctive [Rendall et al., J. Acoust. Soc. Am. 103, 602–614 (1998)], an alternative possibility is that they are aversive to the agonist and that their function may primarily be to discourage further aggression. Noisy screams were recorded in a five-year study of both rhesus and Japanese macaques to determine contextual specificity, structural properties conducive to communication of individual identity, and acoustic features that may be aversive to other macaques. Analyses revealed that these calls were used in a variety of behavioral contexts and did not consistently elicit responses from possible allies. Calls were also routinely composed of multiple segments, including both broad-spectrum noise and various other acoustic features. Combined with the behavioral data, this diversity of features suggests a function of annoying rather than informing conspecifics.
Speech quality in wireless systems
Authors: Gierlich Hans Wilhelm , Krebber Winfried , Kettler Frank
Published: July 2002

Modern wireless communication systems require a very sophisticated design from the electrical as well as from the acoustical point of view. Since the maximum of functionality needs to be integrated in designs—getting smaller with every new generation—not much space is left for the acoustical components. In addition such sets typically are used in noisy environments. In order to provide a minimum of speech quality a careful design of the acoustical components as well as of the according electrical components is required. Very often there is a strong interaction between those. The presentation will describe the typical types of signal processing and acoustical designs used in such sets and will give methodologies on how to assess the speech quality relevant parameters of such sets. Measurements for optimizing the acoustical design will be described. In addition system evaluation procedures for nonlinear and time-variant signal processing are discussed.
Explosive beam spreading due to ray chaos
Authors: Tappert Frederick
Published: July 2002

In an ocean acoustic situation where rays are known to be chaotic, a theory based on a Gaussian beam approximation is used to show that the width of a narrow-angle beam tends to increase exponentially (explosively) with range at the mean rate that is given by the mean Lyapunov exponent that is calculated in the geometric limit. Numerical simulations have been performed with the PE/SSF model that support the theoretical predictions. This finite frequency result shows that the phenomenon of ‘‘wave chaos’’ is real, and might be observable experimentally. [Work supported by ONR, Code 321OA.]
The measurements of the effect of storm-produced bubbles on high-frequency sound propagation
Authors: Goodman Ralph R. , Stanic Stephen J. , Caruthers Jerald W. , Wilson Marcia A.
Published: July 2002

A high-frequency acoustics experiment to measure the spatial and temporal coherence of direct path signals was performed in shallow water, off the coast of Panama City, Florida. Transmission was along acoustic paths between fixed towers at middepth in 10 m of water. During the experiment there were two stormy days with strong winds, breaking waves and, nearby, high surf. It was observed that: (a) average time of arrivals increased significantly over those measured on calm days; (b) pulse to pulse variations in arrival times (over seconds) increased, showing an increase of variance of about a factor of 6, and (c) dispersion was observed. The range between the source and receivers was approximately 60 m. The only known cause for these variations is the presence of bubbles. Although no direct bubble density or distribution was measured, it is possible to construct a plausible bubble model to estimate the total average void fraction along the acoustic path and the variation necessary to cause the increase in variance. Void fractions on the order of 2.6×10−6 and fluctuations of 0.9×10−6 about this value can explain the observed data. [This work was supported by the NRL.]
Acoustic hemostasis
Authors: Crum Lawrence A. , Bailey Michael , Beach Kirk , Carter Stephen , Chandler Wayne , Kaczkowski Peter , Martin Roy , Mourad Pierre , Poliachik Sandra , Vaezy Shahram , Keilman George , Anderson Thomas L , Weng Lee , Perozek David M.
Published: July 2002

When high-intensity focused ultrasound (HIFU) at megahertz frequencies and kilowatt intensities is applied to animal tissue, absorption can result in focal temperatures that exceed 70°C within a few seconds. These high temperatures result in protein denaturization and coagulative necrosis, with the result that bleeding in the capillary bed and within small vessels is rapidly terminated. Additionally, if HIFU is applied to tears or cuts in large vessels, a combination of acoustic streaming and sound absorption can lead to acoustic hemostasis also in a few seconds. The role of acoustic cavitation in this entire process is not clear. We have examined the application of this phenomenon to trauma care and general intraoperative surgery and find that it has many promising attributes. We shall present a general review of our work in this area as well as our most recent results and their clinical implications. [Work supported in part by DARPA.]
On the role of acoustic cavitation in enhancing hyperthermia from high-intensity focused ultrasound
Authors: Edson Patrick , Holt R. Glynn , Roy Ronald A.
Published: July 2002

There are several physical mechanisms that lead to localized heating of tissue and tissue-like media with high-intensity focused ultrasound (HIFU). Experimental results obtained in vivo [Hynynen, Ultrasound Med. Biol. 17, 157 (1991)] and in vitro [Edson et al., J. Acoust. Soc. Am. 104, 1844 (1998)] clearly indicate the existence of an insonation pressure threshold above which cavitation activity can profoundly enhance heating rates at MHz insonation frequencies. The dominant mechanisms through which bubbles facilitate heating have yet to be determined. Candidate mechanisms include viscous dissipation in the flow near the bubble surface, absorption of radiated acoustic waves, attenuation of multiply scattered waves, heat transfer across the bubble wall, etc. Results of numerical simulations designed to investigate the relative impact of these mechanisms on heat deposition from single bubbles and bubbly assemblages are reported. The critical roles of equilibrium bubble size and rectified diffusion are addressed. Our goal is to understand the physics of bubble-mediated heating in order to affect cavitation-enhanced hyperthermia in a reproducible and controllable manner. [Work supported by DARPA.]
Electromechanical material properties for new high-power sonar transduction materials
Authors: McLaughlin Elizabeth , Powers James
Published: July 2002

New high-power electroactive materials such as PMN-PT ceramic and PZN-PT single crystal are being considered for Naval sonar applications. But unlike conventional PZT ceramic, these new materials often have a large mechanical stress and temperature dependence. In this presentation we will describe a method which characterizes the stress and temperature dependence of these new materials under high-drive conditions and present data on several recently measured materials. The measurement generates the quasistatic polarization and strain versus field curves for different values of compressive stress and temperature, and the stress versus strain curve for different values of dc bias field. From these data, the large signal piezoelectric d constant, dielectric constant, short-circuit Youngs modulus, k33 coupling factor, and energy density can be determined. As an example, the large-signal piezoelectric constant for an 80/20/2 (PMN/PT/Lanthanum) material dropped 30% for an increase in temperature of 23°C and dropped 14% for an increase of 34-MPa prestress. For each of the same conditions the coupling factor dropped 13% and the energy density dropped 22% and 13%, respectively. [Work supported by ONR, SPAWAR, and PEO-USW.]
Rayleigh waves in anisotropic porous media
Authors: Kaptsov Alexander , Kuznetsov Sergey
Published: July 2002

Rayleigh waves represent waves propagating in a half-space and attenuating exponentially with depth. During the last 30 years considerable progress has been achieved in developing both analytical and numerical methods for analysis of Rayleigh waves propagating in homogeneous media with arbitrary elastic anisotropy. The propagation of Rayleigh waves in heterogeneous media has not been studied nearly as often. Very few works are devoted to the analysis of speed and attenuation of Rayleigh waves in media (mainly isotropic) with uniformly distributed pores and/or microcracks. The advantage of applying Rayleigh waves to the nondestructive determination of concentration and the preferred orientation of pores lies in its high sensitivity to variation of the material elastic parameters due to preexisting pores. The developed approach for analysis of Rayleigh waves in porous or cracky anisotropic media is based on a combination of six- and three-dimensional complex formalism and the two-scale asymptotic analysis. In its turn, the latter utilizes a newly developed spatially periodic boundary integral equation method. This is used for determination of the effective characteristics of heterogeneous media containing isolated uniformly distributed pores. Numerical data are discussed.
Music, rhythm, and development: Chairs’ introduction
Authors: Palmer Caroline , Riess Jones Mari
Published: July 2002

This special session is sponsored by the Caroline B. Monahan Fund and by the Center for Cognitive Science at Ohio State University. Caroline Monahan’s contributions to the field of music cognition focus on auditory perception and memory, including topics of pitch and temporal parallels in music and speech perception, recognition memory for rhythmic and pitch patterns, and the role of timbral and loudness variables in discrimination of auditory patterns. Dr. Monahan’s work has been concerned with applications of these topics in speech as well as in music, including language acquisition, hearing impairment, and second-language learning. Dr. Monahan received her Ph.D. at UCLA in 1984 in Psychology, and served as a Research Scientist at the Central Institute for the Deaf. She also served as a Research Associate in the Department of Communication Disorders at the University of Oklahoma. We acknowledge her contributions to and generous support of the field of music cognition.
Memory and the experience of time
Authors: Dowling W. Jay
Published: July 2002

Researchers reflecting on the perception of music and speech, from William James a century ago to Eric Clarke very recently (and many in between), have been driven to the conclusion that we do not perceive auditory events instant by instant as they are received by the ear. Rather, we perceive the contents of our working memory where ‘‘sound bites’’ of the order of 5 s in length can be heard. This picture is complicated by the consideration that the contents of working memory are themselves in a state of flux over time. Recent research is reported showing ways in which memory for novel melodies changes systematically over periods of 5 min following presentation. Implications for the understanding of music and the experience of time are drawn.
Children tap faster and within a smaller tempo window than adults
Authors: Drake Carolyn
Published: July 2002

Dynamic Attending Theory [Jones (1976)] proposes that, when listening to auditory sequences, listeners adapt their internal rhythms to those in the sequence (attunement), spontaneously focusing on events occurring at intermediate rates (referent level), and shifting attention to events occurring at faster or slower hierarchical levels (focal attending). The development of these abilities with age and musical training is examined by comparing motor tapping in 4-, 6-, 8-, and 10-year-old children and adults, with or without musical training. Seven motor tapping tasks (including spontaneous motor tempo and synchronization with simple sequences and music) revealed three changes with increased age and musical training: (1) a slowing of mean tapping rate (a reflection of referent period) and mean synchronization rate (a reflection of referent level); (2) an increase in range of tapping rates toward slower rates (improved focal attending); and (3) a greater ability to adapt the taps to sequence structure, in particular incorporating a greater use of the hierarchical structure (improved attunement and focal attending). Interpreted in terms of attentional oscillators, these results suggest that increased interaction and experience with a particular type of sequence facilitate the passage from the initial use of a single oscillator toward the coupling of multiple oscillators.
Selected topics in the history of atmospheric acoustics in North America, 1865–1940
Authors: Blackstock David T.
Published: July 2002

Considered here are three topics in atmospheric acoustics, studied by North American scientists during the 75-year span between the Civil War and World War II. First, in 1865 Joseph Henry (1799–1878), as a member of the Light-House Board, began to investigate fog signaling. His experiments, carried on in friendly competition with John Tyndall in England, added a great deal to our practical knowledge of atmospheric refraction. Second, the first-ever experiments to measure the absorption of sound in the atmosphere were carried out by A. Wilbur Duff (1864–1951) in New Brunswick, Canada, in 1898 and in 1900. The failure of viscosity and heat conduction to account for the measured absorption prompted Lord Rayleigh to postulate that a relaxation mechanism in the air might be responsible for the difference. Finally, George Washington Pierce (1872–1956), who is perhaps best known for his work on piezoelectric and magnetostrictive devices, used an acoustic interferometer to measure dispersion in gases, particularly carbon dioxide. He also measured sound transmission over reflective surfaces. His results confirm the at-first surprising result that at grazing incidence even a very hard boundary seems to act as a pressure release surface.
Finite element analysis of vocal fold posturing
Authors: Hunter Eric J.
Published: July 2002

Steady-state vocal fold posturing was simulated with finite-element analysis using three-dimensional elastic elements. The thyroarytenoid muscle was simulated by applying nodal forces along the fiber direction as measured in our laboratory. Other intrinsic laryngeal muscles and cartilage were defined as boundary conditions or applied loads. Because the arytenoid cartilage forms a complex boundary geometry, the arytenoid was modeled as part of the soft tissue, but with much stiffer, nearly rigid body, material constants. The finite-element model is based on a small displacement vibrational model of the vocal folds [Titze and Scherer, Vocalfold Physiology, Biomechanics, Acoustics, and Phonatory Control, pp. 183–190] and a large displacement model of the tongue [Wilhelms-Tricarico, J. Acoust. Soc. Am. 97, 3085–3098 (1994)]. The medial shape of the modeled vocal folds was compared to published histological data.
Articulatory and acoustic characteristics of emphasized and unemphasized vowels
Authors: Erickson Donna , Fujimura Osamu , Dang Jianwu
Published: July 2002

This study examines the relation between formants, jaw x−y position and tongue dorsum x−y position for emphasized and unemphasized vowels (/ay/ as in ‘‘high,’’ /iy/ as in ‘‘he,’’ and /eh/ as in ‘‘head’’). Acoustic and articulatory measurements were made for target syllables at the moment of jaw height minimum, comparing emphasized and unemphasized conditions of the same vowel. The results can be interpreted as a hyperarticulation of both jaw and tongue movement for emphasis. When emphasized, mandibular position shows increased lowering with forward movement along the front–back axis of the occlusal plane, for all three vowels. The tongue dorsum shows increased raising and fronting for /iy/ and /eh/ but increased lowering and backing for /ay/. The associated F1-F2 show a corresponding spreading apart of F1-F2 for the higher vowels, and a bunching of F1-F2 for the low vowel consistent with the biomechanics of tongue/jaw articulation. These results are interpreted in light of the C/D model which assumes that prosody affects syllable magnitude, which in turn extrapolates the deviation from the neutral gesture along with more opening of the jaw. The C/D model also has the potential to explain timing discrepancies among the extrema as observed in different articulators.
Acoustic and articulatory differences across word position for American English /r/
Authors: Boyce Suzanne E. , Espy-Wilson Carol Y.
Published: July 2002

Typically, American English /r/ is manifested with different formant frequency patterns in word-initial, word-final and word-medial position. In particular, it has been reported (Lehiste, 1962; Espy-Wilson, 1992) that initial /r/’s show lower third formants. This may be due to differences in position or configuration of the primary articulator for /r/—the tongue—or it may reflect an increased degree of lip-rounding. Differences in tongue shape across word position have been reported (Zawadaski and Kuehn, 1982), but it is not clear how reported differences may relate to formant lowering. In this study, eight native speakers of American English recorded words with initial, final and medial /r/’s. Articulatory movements of the tongue tip, tongue blade and tongue dorsum, lips and jaw were tracked simultaneously by Electro-Magnetic Midsagittal Articulometer (EMMA). For each speaker, we compare spatial position, time course, and trajectory for articulators across positional variants. Preliminary data suggest that tongue articulators show similar time course in all three positions. Results are discussed with regard to acoustical modeling studies, theories of articulatory strengthening and interarticulator timing. [Research supported by NIH and NSF.]
Proportional and linear constancy in a repetitive speech production task
Authors: de Jong Kenneth
Published: July 2002

Speech production studies have shown local temporal stabilities in intergestural timing and in its acoustic consequences [e.g., Kent and Moll, JSHR (1975)], such that the absolute duration of certain speech events is remarkably constant over differences in speech rate. Other production studies examining longer stretches of speech have found event durations to be proportionally constant with respect to a larger frame. Proportional constancy is especially apparent in repetitive production tasks [Cummins and Port, J. Phon. (1998)]. This paper examines how absolute constancy, such as would be specified by segmental contrasts, and proportional constancy interact in a repetitive speech task. Speakers repeated linguistically specified syllables in time to a metronome which specified repetition rate. Rates were varied by a factor of 2.7. Durations of speech events which indicate segmental contrasts, such as voice onset time in onset stops, remain fairly constant over these large changes in speech rate. Other durations, such as vowel durations in open syllables, often show proportional constancy. Vowel durations before coda stops, where duration acts as a secondary cue to consonant voicing, often exhibit linear constancy, suggesting a difference in the degree to which linear linguistic factors restrict how speakers perform a repetitive task.
Building and exploring (speech) categories in early infancy
Authors: Lacerda Francisco
Published: July 2002

This paper will report the results from a speech perception study assessing the impact of correlated audio and visual information on category formation in infancy. The amount of speech and of visual information as well as the degree of correlation between the two modalities is systematically varied across subjects and will be subsequently related to the infants’ success in picking up the categories implicit in the multisensory stimuli. Also the infants’ active versus passive role during the conditioning phase is experimentally assessed in an attempt to study how attentional effects may influence the early stages of speech category formation. The study is designed to provide experimental evidence for the notion of emergent phonology and the exemplar-based approach presented by Lacerda (1998) at the 135th ASA meeting, Seattle.
The influence of pitch contour on vowel discrimination in infants
Authors: Trainor Laurel J. , Desjardins Renée N.
Published: July 2002

Because the harmonics are farther apart in high- than in low-pitched vowels, it was predicted that it should be difficult to extract the frequencies of the formant resonances, and therefore, to discriminate high-pitched vowels. Infant-directed speech is very high in pitch, yet studies showing that young infants can discriminate vowels have used low-pitched male voices. The present study showed that 6-month olds were able to discriminate /i/ and /I/ when the pitch was 240 Hz, but were unable to do so when the pitch was 340 Hz, demonstrating that the high pitch of infant-directed speech indeed impedes vowel discrimination. How, then, do infants learn vowel discrimination? The answer may lie with the large pitch contours that are also characteristic of infant-directed speech. Because the harmonic structure follows the frequency of the fundamental, but the formant structure remains relatively constant across frequency shifts, a second prediction was made: discrimination should be better for vowels containing pitch contours than for those with steady pitch. This is exactly what was found. The addition of a downward pitch contour at both high (440–340 Hz) and low (240–140 Hz) pitches significantly improved infants discrimination of /i/ and /I/. [Research supported by NSERC.]
Application of adaptive impulsive noise separation to automotive squeak and rattle detection/quantification
Authors: Tran Vy , Lei Sheau-Fang , Hsueh Keng
Published: July 2002

Abnormal noises such as road-induced squeaks and rattles (S&R) in automobiles are very undesired and perceived as quality risks to the customers. Subjective evaluation by trained experts is the typical S&R assessment procedure for product development and quality control. S&R noises usually have impulsive characteristics (time varying, and transient), and are very difficult to be detected and quantified objectively using traditional signal processing techniques. Emerging wavelet signal processing technique and kurtosis impulsive criteria were used to develop an objective impulsive noise detection and separation technique (US Patent Filed). The method has been shown to work successfully with S&R samples in various frequency bands. The technique has been implemented in a portable PC to acquire or operate on any pre-recorded acoustic signal. The system then automatically detects the presence of any S&R, and separates them from the original composite signal. The results can be played back for listening or processed to characterize, and quantify the S&R noises. These new impulsive noise detection and separation tools have been applied to S&R assessment at the vehicle level and subsystem durability tests. Applications to vibration problems have been envisioned. Conceptually, this technique may also have potential signal enhancement applications in the telecommunication field.
Temporary threshold shift in pinnipeds induced by octave-band noise in water
Authors: Kastak David , Southall Brandon L. , Schusterman Ronald J. , Reichmuth Colleen J.
Published: July 2002

Low-frequency noise from manmade sources represents an increasing portion of the total noise in the ocean. Such noise may adversely impact diving pinnipeds, which hear relatively well at low frequencies. The effects of octave bands of moderately intense noise (under 4 kHz, 60–76 dB SL, 20–22 min duration) were examined in three species of pinniped, the California sea lion (Zalophus californianus), harbor seal (Phoca vitulina), and northern elephant seal (Mirounga angustirostris). Auditory sensitivity data were obtained behaviorally, using a go/no-go psychophysical procedure. Thresholds were determined before noise exposure, immediately after noise exposure, and again after 24 h. Mean threshold shifts ranged from 2.9–4.9 dB at the center frequency of the noise band. Recovery was complete after 24 h. These results show that noise levels as low as 60 dB SL can induce TTS. However, between 60 and 76 dB SL, there was no relationship between noise level and degree of TTS. Additionally, maximum hearing loss occurred at center frequency rather than one-half octave above the center frequency. Further testing at longer exposure durations and higher noise levels is needed to more completely assess the degree to which pinniped underwater hearing is affected by continuous noise exposure.
The carnyx, the lur, and other ancient European horns
Authors: Campbell D. Murray
Published: July 2002

Modern European brass instruments are the result of a long period of evolution. Relatively little is known about their ancestors, the lip-excited horns which were widely used in Europe several thousand years ago. Various attempts have been made to reconstruct playable versions of such instruments as the Scandinavian lur and the Celtic carnyx; although there is a considerable speculative element in all of these reconstructions, they offer the intriguing possibility of carrying out both musical and acoustical tests on these long-vanished instruments. In the last few years a project funded by the National Museums of Scotland has resulted in the reconstruction of two specimens of a carnyx, based on fragments found in Deskford, in Scotland, in the nineteenth century. Only the bell section, in the shape of a boar’s head, had survived, but from other pictorial evidence it is known that the instrument had a tube about 2 m long, and was held vertically. This paper reports on a series of acoustical tests which have been carried out on the two reconstructions, and compares the acoustical and musical properties of the carnyx with those of reconstructed lurs and other ancient horns. [Work supported by EPSRC(UK).]
Generalized state-variable model for the design of a closed-loop differential capacitive accelerometer
Authors: Doust Barry J. , Gabrielson Thomas B. , Schiano Jeffrey L.
Published: July 2002

In an effort to develop a high-performance, miniature, directional acoustic sensor, the advantages of closed-loop operation are investigated. A nonlinear state-variable model of a generalized sensor system is presented. The sensor model is differential capacitive with electrostatic actuation for force rebalance of the proof mass. The physical model parameters are chosen to replicate scales and tolerances of typical MEMS devices with particular attention to nonlinearities associated with the electrostatic force and large deflections. Modeling and simulation will be presented for various control schemes and results will be compared in terms of important operational criteria such as dynamic range, bandwidth, linearity, and noise. [Work supported by the ONR AASERT program.]
Nonresonant referenced laser-induced thermal acoustics (LITA) for measurement of the speed of sound in gases
Authors: Zuckerwar Allan J. , Hart Roger C. , Balla Jeffrey , Herring Gregory C.
Published: July 2002

Nonresonant laser-induced thermal acoustics (LITA) is an effective tool for measuring the speed of sound in gases and is suitable for operation at elevated temperatures. Counterpropagating sound waves of known, fixed wavelength are generated electrostrictively by crossing two split laser beams which are generated from a short-pulse pump laser. The sound waves form a Bragg grating, which is illuminated by a second, long-pulse probe laser. A small fraction of the probe beam is diffracted to a detector, which permits accurate measurement of the sound frequency. Since the method comprises a free-filed measurement, the corrections required of a conventional acoustic interferometer or resonator are not necessary here. The presentation will include the principle of operation of LITA, comparison with other methods of measuring the speed of sound in gases, and sample measurements at temperatures up to 650 K.