bluuebunny/crossref_metadata_2025 huggingface dataset:
A low-frequency projector using giant magnetostrictive rods
Authors: Kawamori Akiyoshi , Yoshikawa Takashi , Tuboi Tomohiro , Nakano Iwao , Tsuchiya Toshio , Nakamura Tosiaki
Published: October 2005

A superior underwater projector having low frequency, high power, high efficiency, and broad bandwidth for the Ocean Acoustic Tomography (OAT) system has been developed. The OAT system is proposed to measure temperature and current distributions of a wide range of sea area with a diameter of about 1000 km on real time by using sound waves. The projector vibrates in the radial mode of octagonal radiating plates connected with eight driving units having giant magnetostrictive rods. The projector is able to emit sound of more than 190 dB [0 dB=1 μPa-m] at a low frequency of about 200 Hz under the operation depth of about 1000 m when it is excited by electric input power of about 900 W. The performance is enough to cover the range of 1000 km for the OAT system. Also, the derived values from measurements are in good agreement with the calculations based on the simple equivariant circuit model.
A reexamination of mode coupling and loss phenomena for simple piezoelectric oscillators
Authors: Smith R. Lowell
Published: October 2005

Applications of both linear and nonlinear theories of piezoelectricity to transduction problems commonly ignore internal material dissipation effects. Such losses can be represented phenomenologically via the introduction of complex dielectric, elastic, and piezoelectric coefficients. However, there is some confusion in the literature with respect to the proper partitioning of electrical and mechanical attributes in the presence of piezoelectric coupling. This paper is a review of this situation wherein dissipation coefficients are motivated from more fundamental physical insights. Equivalent circuit models are useful both for developing this perspective and summarizing the results. Suggestions are also presented for generalizing the celebrated Mason model to include the coupling of orthogonal modes via Poisson dilation. This formalism is intended to provide straightforward procedures for computing piezoelectric oscillator performance characteristics using a personal computer. The approach is evaluated via regression analysis in terms of its self-consistency for interpreting Tonpilz oscillator admittance data. The procedures developed are expected to be applicable for the interpretation of data associated with a variety of other electroacoustic structures.
Some second thoughts on electromechanical coupling
Authors: Ge Li-Feng
Published: October 2005

An electromechanical transducer can be regarded as an energy converter, and also as an impedance inverter. It could be significant for understanding the transduction process to introduce a new generalized concept, inversiveimpedance, which is defined as a ratio of the open-circuited voltage caused by a motion at the mechanical end of a transducer to the exciting current required to produce the same motion, i.e., a ratio of the receiving (voltage) sensitivity of a transducer to its sending (current) sensitivity. Thus the electrical driving-point impedance is composed of an impedance without coupling and a inversive impedance, which is induced by electromechanical coupling, and is constant at a given frequency for a particular transducer. The transduction process or the impedance inversion process can be described by only three independent parameters [L.-F. Ge, J. Acoust. Soc. Am. 91, 2326 (A) (1992)], and determined uniquely by a mapping between the electrical driving-point impedance and its mechanical load impedance. It is an inherent physical property independent of analogy-type chosen and mathematical representation that a piezoelectric-type transducer is reciprocal, and an electrodynamic-type transducer is antireciprocal. Thus there exists, respectively, an optimum way to perform reciprocity calibration for the two types of electromechanical transducers.
Wideband array transducer
Authors: Kim Chun-Duck , Yoon Jong-Rak
Published: October 2005

There is a need to develop a wideband underwater sound source. This need can be accomplished by an array of different resonance frequencies of transducers. An axisymmetric array transducer, which consists of three different size piezoelectric cylinder elements, is designed and its coupled electrical, mechanical, and acoustical characteristics are evaluated using the combined single code finite element method and hybrid-type infinite element method. The numerical result of electrical input impedance is consistent with the measurement result using an impedance analyzer and is shown to be better than that by Warren P. Mason’s equivalent circuit modeling method. Its bandwidth and directivity pattern are also obtained and its limits as underwater sound projector are discussed.
Thermodynamic property considerations for modeling piezoelectric ceramic vibrators including thermal effects
Authors: Moon Won-kyu , Busch-Vishniac Ilene J.
Published: October 2005

The thermodynamic characteristics of piezoelectric ceramics are investigated by considering two thermodynamic material property models: isentropically linear and isothermally linear models. Those two models are two possible interpretations of the data on temperature-dependent linear coefficients of piezoelectric ceramics. Thermodynamic differences of the two models are examined and effects of the thermo-electro-mechanical couplings are evaluated in examples. Application of the thermo-electro-mechanical model to PZT4 shows that the difference observed in piezoelectric constants obtained by static and dynamic measurements cannot be explained by the difference between isothermal and isentropic processes.
Cooling low-frequency sonar projectors by heat transfer optimization
Authors: Dubus Bertrand , Bigotte Patrice , Grosso Gilles , Boucher Didier
Published: October 2005

Heating has become a critical issue for low-frequency projectors due to their high dissipated power density and long excitation time. In this paper, the cooling of sonar projectors in terms of heat transfer optimization is presented. An analysis of the projector heating requires the description of the heat conduction in the structure and the heat exchanges with the surrounding medium. This analysis is performed in steady state using both analytical (thermoelectrical analogies) and numerical (finite element) models. For the reference transducer (double-ended longitudinal piezoelectric vibrator), the temperature distribution and heat fluxes are computed. The temperature decrease and the importance of various heat paths are evaluated for various techniques of cooling. Practical considerations (simplicity, fiability, cost, size) and cooling efficiency are both taken into account to determine the optimal solution. At constant dissipated power density, the maximum temperature is theoretically divided by 3. Temperature measurements on reference and optimized projectors are provided and compared to predictions. Extension of the technique to other geometries of projectors and other types of active materials (magnetostrictive, electrostrictive) is discussed.
Scattering of sound by sound within the interaction zone
Authors: Westervelt Peter J.
Published: October 2005

Starting with Eckart’s equation for ρs the scattered density [P. J. Westervelt, J. Acoust. Soc. Am. 29, 934 (1957)], ⧠2ρsc20=⧠2E12 −∇2(2T12+ΛV12), the variables x0=c0t and ψ,0=−(4ρ0c20)−1/2p are introduced for which ⧠2ψ=0, ⧠2ψ2=T12−V12, and ∇2V12=⧠2V12+(V12),00 to obtain ⧠2[ρsc20+T12+(Λ−1)V12 +2(ψ2),00]=−2(2+Λ)[(ψ,0)2],00. Next it is assumed that ψ=φ+χ, where φ(x0−n⋅r) is a plane wave and χ,0=σ,0+n⋅∇σ, where σ(x0,r) is an arbitrary wave. Terms bilinear in φ and χ are retained; thus (ψ,0)2=2χ,0φ,0, and since ∇φ=−nφ,0, it is found ⧠2(σφ)=2∇σ⋅∇φ−2σ,0φ,0=−2φ,0 χ,0, leading to the solution of Eckart’s equation, ρsc20=(2−Λ)V12−E12 +2[(2+Λ)σφ−ψ2],00, valid within the interaction zone, but vanishing outside where V12=E12=σ=φ=ψ=0. The feasibility of making optical measurements of ρs is being investigated.
Criticism of experiments on the scattering of sound by sound
Authors: Trivett D. H. , Rogers Peter H.
Published: October 2005

At the 127th meeting of the Acoustical Society of America, Westervelt [Peter J. Westervelt ‘‘Answer to criticism of experiments on the scattering of sound by sound,’’ J. Acoust. Soc. Am. 95, 2865 (A)] stated that a recent experiment by Roy and Wu [R. Roy and J. Wu, in Proceedingsofthe 13thISNA, edited by H. Hobæk (Elsevier Science, London, 1993)] supported the position that there was no signal scattered out of the interaction region of two perpendicular, collimated sound beams. In this paper, an analysis of the Roy and Wu experiment is presented, specifically, and of previous experiments, in general, which have failed to find any scattering of sound by sound. The analysis indicates that the null results of the experiments do not necessarily support theoretical null predictions.
Extensions of the theory for nonlinear Rayleigh waves
Authors: Knight E. Yu. , Hamilton M. F. , Il’insky Yu. A. , Zabolotskaya E. A.
Published: October 2005

The derivation of Zabolotskaya’s coupled spectral equations for nonlinear Rayleigh waves in isotropic solids [J. Acoust. Soc. Am. 91, 2569 (1992)] applies to plane, progressive, periodic waves. These assumptions are removed here in a more general derivation based on the Hamiltonian formalism employed in the original work. Via methods described in Paper 4pPAa12 of this session, the resulting spectral equations are transformed into time domain evolution equations. Model equations for cylindrical waves and diffracting beams, obtained previously via adhoc modification of the plane-wave model, can be derived rigorously from the new generalized equations. The nonlinear terms are shown to be equivalent to those obtained previously by Parker [Int. J. Eng. Sci. 26, 113 (1985)] by entirely different methods. Numerical results for the shock formation distance are used to define an effective coefficient of nonlinearity that is consistent with the corresponding parameter for sound waves in fluids. The coefficient is of order one for common isotropic solids, as for the case of fluids, but it is several orders of magnitude larger in rock with microcracks and other inhomogeneous features. [Work supported by DOE, ONR, and NSF.]
Theoretical model for nonlinear Stoneley and Scholte waves
Authors: Meegan G. Douglas , Hamilton Mark F. , Zabolotskaya E. A.
Published: October 2005

The Hamiltonian formalism used previously to derive model equations for nonlinear Rayleigh waves [Zabolotskaya, J. Acoust. Soc. Am. 91, 2569 (1992)] is used here to obtain a mathematical model for nonlinear Stoneley and Scholte waves. Planar interfaces formed by contact between two isotropic materials are assumed. The resulting coupled spectral equations are expressed in the same form as those for Rayleigh waves. In particular, the nonlinearity coefficient matrix can be written as RSml= R(1)ml+KR(2)ml, where K is a constant and R(i)ml (corresponding to medium i=1,2) are matrices having the same mathematical form as the matrix obtained for Rayleigh waves. Since RSml exhibits the same symmetries as the nonlinearity matrix for Rayleigh waves, the model equations for Stoneley and Scholte waves can be analyzed with the same mathematical techniques that have been employed in recent investigations of nonlinear Rayleigh waves (see, e.g., other papers in this session). The coupled spectral equations were solved numerically for Stoneley and Scholte waves at interfaces formed by a variety of media pairs, including some geological materials. Comparisons of harmonic generation and shock formation are made with the corresponding processes in Rayleigh waves. [Work supported by AASERT and ONR.]
Generation and propagation of high intensity short acoustic pulses in dispersive media
Authors: Esipov I. B. , Naugol’nykh K. A. , Ovchinnikov O. B. , Pashin A. E. , Zozuly O. M.
Published: October 2005

Experiments on laser generation of acoustical pulses, amplitude 10 MPa and duration 1 μs, and their propagation in different liquids have been carried out. Propagation was measured in both pure liquids and structured media. Nonlinearity and dispersion caused evolution of the propagating signals. Some theoretical treatment of the results indicate the possibility of obtaining data on spectral features of the nonlinear response of the medium.
The nature of top-down representations that affect bottom-up phonemic processing in children and adults
Authors: Bauman Angela L. , Goodman Judith C.
Published: October 2005

Adults and children use lexical knowledge to interpret phonemes in speech [W. F. Ganong, JEP: HPP 6, 110–125 (1980); Hurlburt and Goodman, in preparation; S. Nittrouer and A. Boothroyd, J. Acoust. Soc. Am. 87, 2705–2715 (1990)]. This study examines the nature of lexical representations necessary for top-down effects. In a baseline assessment, 5-year-olds and adults heard stimuli from seven-step voice onset time (VOT) continua. The continua endpoints formed nonwords (e.g., beb_→peb_). Subjects were then trained on one endpoint from each continuum in one of two learning conditions. Subjects in the exposure condition heard items in a carrier phase five times (e.g., ‘‘The sound you will hear is peb_.’’). Subjects in the concept condition heard five instances of each item used as a picture label, in definitional sentences, and in a sentence identifying its superordinate category. After training, subjects again heard the baseline VOT continua. Children’s and adults’ phoneme boundaries shifted such that a greater proportion of tokens were perceived as compatible with the trained end of the continuum regardless of learning condition. This suggests that minimal exposure to a sound pattern, rather than fully-specified lexical knowledge, can result in top-down effects in speech perception.
Prototype preference and magnet effects in newborns: Evidence for an innate component
Authors: Aldridge Michelle
Published: October 2005

Within the vowel space there are subareas which correspond to specific vowel categories. Within each subarea there is a point which defines the bestexemplar or prototype of that vowel. Kuhl [J. Phon. 21, 125–139 (1993)] has argued that the area immediately surrounding a prototype is perceptually shrunken, with reduced variance in responding to points in that immediately surrounding area, a magneteffect [Kuhl (1993)]. Empirically, prototype points correspond to the averages of large numbers of utterances. This leads to the hypothesis that prototypes are learned. It is equally possible that prototypes are innate [Kuhl (1993)]. To decide between these two hypotheses an experiment was run with newborns. The vowel /y/ was used in the experiment; /y/ does not occur in Texas. The newborns’ only experience was provided in the experiment. ‘‘Best exemplar’’ was equated with ‘‘most attractive’’ measured by listening time in an operant choice task. Results indicated that experience did not determine preference. The prototype /y/ was preferred, regardless of the experience provided. No significant magnet effect occurred. A second, slightly different, experiment did find a magnet effect. The difference between the two experiments may explain why the magnet effect occurs.
Maturational limitations to pronunciation accuracy in a second language
Authors: Yeni-Komshian Grace H. , Flege James E.
Published: October 2005

This study examines pronunciation proficiency in a second language (L2) as a function of the age of (L2) acquisition. Accuracy of pronunciation of words and sentences produced by Korean–English bilinguals who began learning their L2 (English) between 2 and 24 years of age is reported. All subjects were born in Korea and had resided in the U.S. for at least 8 years. Their average age at the time of testing was about 24 years. The results are based on the subjects’ accuracy of pronunciation of vowels and consonants in English words and sentences. Preliminary findings, regarding segmental phonemes, indicate no major difficulties up to about 11 years for L2 acquisition. Those who learned English (L2) at or later than 12 had significantly lower pronunciation accuracy scores. These difficulties were more evident in vowels than in consonants. The results support the critical period for language learning hypothesis. The discussion will address the problem of specifying the optimum conditions for second language acquisition and first language retention.
Towed vertically directive source for shallow-water scattering measurements
Authors: Goldsberry Tommy G. , Monti Joseph M. , Werbicki Michael
Published: October 2005

A unique tool for low/mid-frequency (LF/MF) shallow-water reverberation and scattering measurements has been developed. The towed vertically directive source (TVDS) is designed to overcome the two critical deficiencies in most attempts to measure LF scattering characteristics of the ocean bottom in shallow water—insufficient source level and inadequate directivity of the sound source. Although TVDS provides high source level and directivity at LF and MF (220 to 230 dB over the frequency band from 400 to 4000 Hz) it is designed for use on 3000 ton research vessels at tow depths to 180 m. An articulated strut allows aperture for a 20 deg vertical beamwidth at 600 Hz but permits TVDS to be deployed and retrieved with the low-frequency array retracted. An MF array with center frequency of 3000 Hz is mounted in the vertical stabilizer of TVDS and also provides a 20 deg vertical beamwidth. Provision for simultaneous transmission at LF and MF will permit frequency diversity in measurements over a decade of frequency with scattered signal reception on the TVDS transducer arrays or an adjunct towed array. TVDS design and test results will be discussed. [Work sponsored by ONR.]
An assessment of the variability of low-frequency active sonar performance in shallow water
Authors: Franken Jeroen , Chiu Ching-Sang , Miller James H. , Denner Warren W.
Published: October 2005

The performance of a generic low-frequency, active sonar was simulated using a broadband, coupled mode, propagation model. The low-frequency active system consisted of a 1000-Hz source with source level of 220 dB and a towed horizontal array of hydrophones. The ocean environment used in the simulation was 159 tomographic snapshots of the Barents Sea Polar Front, taken every 5 min. These tomographic images over a range of 35 km provide a virtual ocean in which system performance and environmental data requirements can be assessed. The probability of detection calculated as a function of time for 13 h is compared with that estimated using a range- and time-independent assumption. The importance of coastal acoustic tomography for tactical applications will be discussed.
Reverberation characterization and suppression in the presence of channel spreading
Authors: Edelson Geoffrey S. , Kirsteins Ivars P.
Published: October 2005

In active sonar, the reverberation plus target time series can be modeled as the joint convolution of the signal with the channel and scatterer impulse responses. Especially in shallow water, the channel response cannot be adequately modeled as propagation over discrete paths. A maximum likelihood type approach is proposed for estimating the arrival times of signals which have propagated via a continuum of paths, i.e., temporally spread channels. The channel spreading is included in the model by using a discrete prolate spheroidal sequence (DPSS) to represent the channel impulse response of given duration, but unknown shape. Thus the unknown parameters are the arrival times and the scale factors of the DPSS expansion. The parameters are estimated using an iterative methodology which decomposes the original data into its constituent components and then estimates the parameters of the individual components through a sequence of one-dimensional searches. Experimental data and computer simulation examples indicate that the method performs well.
Improvement of ultrasonic synthetic aperture imaging via deconvolution preprocessing
Authors: Ishikawa Nobuyuki , Fujii Yoshio , Shinohara Yoshikuni
Published: October 2005

Ultrasonic synthetic aperture imaging is a useful technique for detecting cracks in the material and viewing the underwater environment. Since high-frequency ultrasonics are utilized for such purposes, transducers with sufficient transient response have been made available. On the other hand, ordinary transducers for measurements in air are of the resonant type because of comparatively low practical frequency used. However, the utilization of resonant type transducers for synthetic aperture imaging in air makes the measurement resolution poor. This degradation comes from the narrow-band characteristics of transducers, which cause signal distortion in transduction. In this study, to compensate for the narrow-band characteristics of transducers, a deconvolution technique is applied for preprocessing of synthetic aperture imaging and improvement is attained thereby in the case of using the resonant type transducer. The filter used for deconvolution is of the FIR type which is designed in the time domain. The desired filter output has bandpass characteristics with a center frequency of 40 kHz corresponding to the resonant frequency of the transducer and the passband is 6 kHz. Experimental results show that resolution of synthetic aperture imaging is improved by a factor of 3.0 in the range direction and 3.5 in the lateral direction by using deconvolution processing.
A generalized framework for high-frequency optimum target detection in a shallow water, random wave scattering environment
Authors: Premus V. , Alexandrou D. , Nolte L. W.
Published: October 2005

It has been shown that for the case of Gaussian reverberation, the likelihood ratio detector can be made robust with respect to inexact knowledge of the acoustic scattering medium by incorporating a probabilistic description of environmental uncertainty and a model for the wave-number spectrum of the bottom-interacting acoustic field [Premus etal., J. Acoust. Soc. Am. (submitted)]. In this work a generalized form of the optimum detector is presented which requires full-field (amplitude and phase) modeling capability for the scattered field and relies on Monte Carlo integration to treat environmental uncertainty. The performance of the generalized detector formulation is compared to that of the original detector formulation, which is a special case based on explicit modeling of the reverberation second-order statistics that is exact for the case of Gaussian reverberation. Tradeoffs involving the prior knowledge, modeling assumptions and computational requirements are discussed. [Work supported by ONR, Ocean Acoustics.]
Prosodic features of foreigner talk register in the speech of 10- to 11- and 6- to 7-year-old American children
Authors: Sullivan Jennifer , Levitt Andrea G.
Published: October 2005

At what age and in what ways do children begin to modify their speech in the presence of a non-native speaker? Two groups of six American children each, three girls and three boys, were asked to teach two children, one a native speaker of English and another with limited English proficiency, to recite the pledge of allegiance and two children’s poems. The children in the older group were between 10 and 11 years old, and those in the younger group were between 6 and 7. When speaking to the non-native child, the older group of children produced shorter utterances, repeated often, and spoke significantly more slowly than when speaking to the native speaker. Repetitions were generally spoken with a lower F0, and the older children also used a significantly reduced F0 range when addressing the non-native speaker. There were no differences in the prosodic adjustments made by the boys and the girls. The children in the younger group generally made few modifications in their speech to the non-native child, although some of the older subjects in this group occasionally modified their speech to the non-native speaker in ways similar to those of the older children. [Work supported by NIH Grant No. 1 R15 HD28173-01.]
Remote identification of moving acoustic objects
Authors: Dwyer Roger F.
Published: October 2005

Often in applications it is desired to remotely identify an object from its acoustic signature. In active sonar the object is insonified by a transmitted waveform and the received pressure is processed to localize and identify the object. Here, the received pressure time series from spherical acoustic objects in motion that have been insonified by linear frequency modulated (LFM) waveforms are used to identify the objects. The unknown object’s unknown constant velocity using a unique property of the fourth-order cumulant spectrum [J. Acoust. Soc. Am. 93, 1460–1465 (1993)] is extracted and then its transfer function is extracted. The results for five spherical acoustic objects in motion are discussed. Three methods, deconvolution, matched filtering, and fourth-order cumulant spectrum deconvolution to extract the object’s transfer function are compared.
Towed array geometry estimation during ship’s maneuvering
Authors: Jesus S. M. , Felisberto P. , Coelho F.
Published: October 2005

Towed arrays of hydrophones are commonly used as receiving apparatus for determining the directionality of the underwater acoustic field. It is well known that a line array beam response has an inherent left–right ambiguity and that any deformation of the array will produce a distortion on the estimated acoustic field directionality. In particular, the array cannot be operated during ship’s maneuvering which is a potential drawback to its operational usage. In theory, if the array is not straight but the hydrophone’s position are known at each time instant, the beamformer could be compensated in order to obtain a corrected beam response. More, depending on the array shape, the left–right ambiguity could also be resolved. In practice, it is extremely difficult to obtain sufficiently accurate measurements of the hydrophone positions. This paper presents the measurements obtained at sea, with a 156 m aperture array, instrumented with several high precision tiltmeters, compasses, depth sensors, and accelerometers. After filtering and preliminary analysis of the sensor position data it is concluded that the array is never a straight horizontal line. The array has approximately a catenary shape with vertical deviations at the tail up to 15 m at constant tow speed. Under maneuvering, the array is largely deformated and a consistent shape could be estimated on real time from the nonposition sensors. The use of the estimated geometry for acoustic data processing, shows that consistent beam responses (close to theoretical) could be obtained even under strong array distortion. It is also shown, with real data, that the knowledge of array geometry significantly improves full-field matching for source localization and/or bottom characterization.
A fundamental study of multipath localization using bottomed receivers in shallow water
Authors: Smith Randall W. , Nualart Jaime F. , Grant David E.
Published: October 2005

The basic characteristics of multipath propagation from a shallow source to a bottomed receiver in shallow water are investigated, with an emphasis on application to the problem of source localization. For this fundamental study, the environment is assumed to be ideal (perfectly reflecting bottom and surface, range invariant depth, isovelocity). The delays between travel times along different propagation paths depend on the location (range, depth, and bearing) of the source relative to the receiver. Measurements of several such time delays can be used to determine the location of the source. It was found that the travel time difference between paths having differing numbers of traversals of the water column depends strongly on range but weakly on depth. In contrast, the travel time difference between paths having an equal number of traversals but which have different source angles (i.e., up or down) depends strongly on depth but weakly on range. As an example, these observations are applied to localize a towed sound source in a real environment. The example provides a background for an assessment of how accurately a real environment must be modeled in order to obtain reasonable results.
Otoacoustic emissions in animals: An intricate view of the peripheral stage of acoustic processing
Authors: Lonsbury-Martin Brenda L. , Martin Glen K. , Whitehead Martin L.
Published: October 2005

Otoacoustic emissions (OAEs) represent sounds generated by the ear that can be simply measured from the ear canal. In particular, OAEs provide a means to examine in detail the encoding properties of the outer hair-cell system, which presumably generates emitted responses. Animal research using emissions as a response measure consists of four general classes of utilization including the use of OAEs: (1) to describe the basic limits of auditory function for a particular species, (2) to monitor or index cochlear function during experimental manipulations of the auditory system, (3) to enhance understanding of the fundamental nature of the various emissions, and (4) to further knowledge about the physical basis of certain afflictions that affect human hearing using animal models of specific pathologies. The purpose of this presentation will be to provide an overview of OAEs including their essential basis, to review the equipment and procedures used to adequately detect this response measure, and to present examples of the unique applications of emission measurements in animals. By reviewing these many aspects of OAEs, the great benefits along with the limitations inherent to this attractive research technique can be appreciated. [Work supported by PHS (DC01668, ES03500).]
A preliminary investigation of how prosodic cues may help young infants’ to extract words from natural sentences
Authors: Lacerda Francisco , Sundberg Ulla , Andersson Christin
Published: October 2005

This paper presents preliminary results of a study assessing 6-month-old infants’ capacity to pick up linguistically relevant information presented in complex naturalistic linguistic contexts. The head-turn procedure was used to investigate the infants’ ability to discriminate target words that are embedded in natural carrier sentences. The sentences were produced as infant-directed or adult-directed speech (‘‘direction’’) and for each direction of the target word occurred either in emphatic or nonemphatic position (‘‘focus’’). A large number of sentences, including all the possible combinations of direction and focus, was first submitted to adult scrutiny in order to select unambiguous carrier sentences in which adequate target words were subsequently edited. Both adults and infants were tested by the head-turn procedure, to assess the differences between the infants’ and adults’ use of the prosodic information. [Research supported by The Bank of Sweden Tercentenary Foundation, Grant No. 94-0435.]
The role of passive sonar technology in marine mammal population assessment
Authors: Evans William E. , Benson Robert
Published: October 2005

When sonar detection of marine organisms is mentioned most every one visualizes active sonars. This is because development of passive sonar systems has been essentially limited to military use until recently. With the development of new designs, submarines could run deeper and more silent than in the past. The development of more sensitive listening systems was essential. With the development of improved passive sonars, a vast variety of biological noise mostly generated by cetaceans was documented. Most dolphins and whales are either direct or incidental noise makers. In many cases sound generating cetaceans can be identified as to family and in some cases to species (e.g., Physetermacrocephalus, Tursiopstruncatus). In 1992 The Texas Institute of Oceanography, Center for Bioacoustics, Texas A&M University, in partnership with the National Marine Fisheries Service, Southeast Research Center, conducted a three-year acoustic/visual seasonal census of the cetaceans of the Gulf of Mexico. A linear towed array and sonobouy arrays were used. Thirteen of the 21 species of cetaceans known to occur in the Gulf of Mexico were detected acoustically using the towed array. Acoustic contacts were compared with the distribution and density of these species determined by the visual survey. The use of a mobile directional acoustic array had the advantage of detecting the presence of cetaceans 24 h a day. Because of this the number of acoustic contacts was significantly greater than those for the visual survey. In the case of the sperm whale it was possible to assess the distribution and also estimate the population density.
Zooplankton population density assessment with acoustics
Authors: Holliday D. V.
Published: October 2005

There are a variety of acoustical methods which can be used as tools in basic and applied research in biological oceanography, estuarine ecology, and in limnology. The mode of application of these tools is often as important and interesting as are the sensor characteristics. Two such sensor systems, the TAPS and the BITS, are being used to sense and describe temporal and spatial distributions of small zooplankton insitu. These sensors operate as active sonars at discrete, multiple frequencies from hundreds of kilohertz to several megahertz. Acoustical design parameters and the mode of deployment for several of these systems will be presented. TAPS operates in either a profiling mode or in a cast mode. BITS estimates zooplankton abundance at discrete depths from a mooring and telemeters the data to shore. Data from both will be used to illustrate their application in both marine and estuarine ecosystems science. Illustrations of the acoustical data each of these systems produces will be illustrated, along with several ancillary abiotic measurements and derived estimates of the size structure and biomass of the underlying population of zooplankton that causes the scattering. [Work supported by ONR Oceanic Biology, NSF Biological Oceanography, and Tracor.]
Dynamics of dolphin biosonar search and detection
Authors: Sigurdson J. E.
Published: October 2005

The biosonar emissions of a free-swimming dolphin were measured with respect to direction and timing while the animal searched for and reported objects at various ranges and bearings from a test enclosure. The technology allows a quantitative description of the pulse-by-pulse scan pattern of the freely moving animal and subsequent inferences about search strategies, echo-integration time, functional beam coverage, and learning effects on biosonar performance. Presently, the methods are being extended to test an animal from a boat in the open ocean with measurement of the animal’s attitude and movement in three dimensions as well as the spectral content of emitted pulses during search, detection, and discrimination. The technique combines standardized test paradigms, and instrumentation pack carried by the animal, and a positioning system. The animal’s pack is a self-contained, data-acquisition system with sensors for magnetic azimuth, acoustic emissions, attitude, and motion. It is based on a high-speed, real-time microprocessor with open software architecture for maximum flexibility. The positioning system employs a high-accuracy real-time differential GPS for prepositioning targets and monitoring the position of the boat and animal during a search.
On the use of Schrödinger’s equation in the analytic determination of horn reflectance
Authors: Berners David , Smith Julius O.
Published: October 2005

The flaring horn has traditionally been modeled in one dimension using piecewise conical or cylindrical elements. Acoustic properties within each element are known, and scattering between the elements is computed. Under the piecewise model, a shape for the wavefront of the acoustic disturbance within the horn is implicitly assumed (planar for cylindrical elements, spherical for conical elements). For horns of significant flare, the true wavefront shape will be neither planar nor spherical. A more general model is thus desirable. Here an alternate model is presented: The flaring horn is modeled according to Webster’s equation. A change of variables transforms the equation into the form of the Schrödinger wave equation using in one-dimensional particle scattering. Boundary conditions can be derived directly from the physical dimensions of the horn, and the solution of the equation gives estimates of acoustic properties in terms of frequency dependent reflection and transmission coefficients. Here, Webster’s equation is solved along the entire length of the horn, with no lumped scattering. Advantages over piecewise modeling techniques include the ability to specify arbitrary axisymmetric wavefront shapes for the acoustic disturbance within the horn. Under appropriate assumptions for wavefront shapes, results converge to those obtained with traditional piecewise models.
The wave digital hammer: A computationally efficient traveling wave model of the piano hammer and the felt mallet
Authors: Van Duyne Scott A. , Smith Julius O.
Published: October 2005

Recent work has led to traveling wave string and membrane models using the digital waveguide and the 2-D digital waveguide mesh. This paper introduces a new development for these musical instrument models which extends their usefulness: a traveling wave model for the piano hammer, or felt mallet. When a mallet strikes an ideal membrane or string, it sinks down into it, feeling a pure resistive impedance. In the membrane case, the depression induces a circular traveling wave outward. If the membrane is bounded, reflected waves return to the strike point to throw the mallet away from the membrane. This complex mallet–membrane interaction can have very different and difficult to predict acoustical effects, particularly when a second or third strike occurs while the membrane is still in motion, as in a drum roll. The piano hammer, or felt mallet, is viewed as a nonlinear mass/spring (inductor/capacitor) system, the nonlinear spring representing the felt portion. By decomposing the system into appropriate traveling waves, a unit of delay is extracted in the discrete time version, greatly simplifying the implementation. This wave digital hammer can be attached to any waveguide string or membrane model at a time-varying lossless scattering junction.
The pitch of elements of a harmonic complex
Authors: Anderson Blane , Ward W. Dixon
Published: October 2005

It is well established that the pitch of a sinusoid is shifted away from the frequency of a simultaneous noise band or sinusoid. Attempts to determine whether or not such pitch shifts occur among elements of a harmonic complex tone have given results that are apparently conflicting. In an endeavor to shed light, or at least a few shadows, on the question, seven listeners adjusted a sinusoid to match the pitch of either the 3rd or 7th harmonic of a preceding 220-Hz 8-harmonic complex in which the harmonic in question was periodically interrupted. Both monotic and dichotic procedures, with corrections for diplacusis, were employed in order to control for possible adaptation effects. On average, the pitch of the 7th harmonic was shifted upward by about 25 cents due to the presence of its neighbors, but the pitch of the 3rd harmonic was unaffected. In both cases, however, consistent individual differences were found, so that no unequivocal conclusions can be reached.
Technical and aesthetic considerations in interactive computer music systems
Authors: Winkler Todd
Published: October 2005

The proliferation of reliable interactive computer music systems has created opportunities for performers to directly influence computer music processes. Performing musicians are highly valued for their unique sense of musical expression and taste: the ever-changing subtleties of tempo, dynamics, timbre, and articulation encompassed in the larger musical framework of musical gesture and phrasing. How can musicians communicate their highly refined skills to a computer, and elicit similarly musical results? This paper describes techniques whereby performers influence highly flexible compositional algorithms that are subtly responsive to musical nuances. These algorithms create MIDI data used to control synthesizers and signal processors. Musical examples will be demonstrated using FollowPlay, a computer program for interactive music and a real-time environment for music composition. The program consists of a large collection of software modules organized into three functional types: Listener Objects analyze and record aspects of a musician’s performance, Composition Objects respond by generating MIDI data, and Interpreter Objects unify the entire collection with a graphical user interface that handles timing and intermodular communications.
A touch sensitive dance floor/MIDI controller
Authors: Pinkston Russell F.
Published: October 2005

A prototype MIDI Dance Surface has been developed which is capable of transmitting precise position coordinates, velocity, and pressure information in the form of standard MIDI messages. The surface consists of a large number of force sensing resistors (FSRs) which are attached to heavy duty plastic sheeting and covered with polyethylene foam. The sheets may either be placed on top of or beneath a standard Marley Dance floor. The FSRs are typically arranged in a grid with 16 columns (left to right) and 4 rows (front to back), which results in a 16 ft. square dance surface with 64 1×4 ft. velocity and pressure sensitive regions, each of which is assigned a separate input channel of a Voltage to MIDI Interface Box which has 64 analog inputs, plus MIDI Out. The MIDI Box incorporates a Motorola MC68HC11 microprocessor and can be programmed to convert input/output analog signals to/from any desired MIDI messages, on multiple MIDI channels. Hence, used in conjunction with an ‘‘intelligent’’ external MIDI processing system, it is ideal for use in interactive dance compositions in which one or more dancers can affect both the music and lighting by the nature of their movements and by their precise position(s) on the surface.
Effects of processing audio signals through equivalent color matching filters
Authors: Blackford Andrew , Espinoza-Varas B.
Published: October 2005

In applications that combine musical sounds with visual colors, it is relevant to define rules that may relate color dimensions to the pitch and timbre of sounds. In a first attempt toward defining such rules, this investigation examined effects of processing audio signals through equivalent color matching filters. Using Butterworth bandpass filters, a three filter bank (f1, f2, f3) was designed to approximate the response of filters used in the CIE 1931 Standard Observer [G. Wyszecki and W. S. Stile, ColorScience (1982)]. The bandwidths of the color-matching filters were transposed to the audible frequency range (0.02–20.0 kHz); the filter passbands were 0.05–0.6 kHz and 9.0–11.0 kHz for f1, 1.0–4.0 kHz for f2, and 9.0–11.0 kHz for f3; the passband gains were 1.15, 0.35, 1.0, and 1.75, respectively. Synthesized audio signal were passed through the filter bank and the power, P, at the filter outputs was computed. The P values were used to specify the X and Y coordinates of CIE chromaticity diagrams as follows: X=Pf1/(Pf1+Pf2+Pf3); Y=Pf2/(Pf1+Pf2+Pf3). Chromaticity diagrams were obtained for: (a) 0.07–8.0 kHz sinusoids; (b) vowels with different fundamentals; and (c) complex sounds consisting of 2-21 equal-energy sinusoids. [Work supported by OCAST.]
Waves and rays on fluid-immersed shells: Beyond spheres, cylinders, Donnell, and Watson
Authors: Pierce Allan D.
Published: October 2005

Waves propagating along ray paths on shells have various descriptors, such as the dispersion relation that connects frequency and the two principal wave-number components for each point on the surface. Other descriptors include polarization relations: complex ratios of amplitudes of quantities that oscillate under the influence of a propagating wave. Such oscillating quantities include the components of the displacement vector for points on the middle surface, the acoustic pressure at the external surface, and the locally-spatially-averaged passive forces exerted on the shell by the internal structure. Energy balance relations are also wave descriptors. Such descriptors are derivable directly from the equations of elasticity and fluid mechanics. In any frequency and wave-number regime (associated with the ranges of scales for the intended application) there are a limited number of possible waves types, but analogies with waves on flat plates are often not appropriate. The use of wave-based theory depends on whether the wavelength along the direction of propagation is somewhat smaller than the effective shell radius associated with that direction. It is not necessary for the frequency to be high and/or for the wavelength to be smaller than both of the principal radii of curvature. Radiation of sound into the fluid from waves traveling slower than the speed of sound is possible as long as there is some point above the surface at which the extrapolated phase velocity is supersonic; the explanation is analogous to why propellers with subsonic tip speeds radiate sound. [Work supported by ONR.]
Backscattering enhancements and the impulse response of shells: Observations and ray theory
Authors: Marston Philip L. , Kaduchak Greg , Hughes David H.
Published: October 2005

Observations of backscattering by thin spherical shells in water were carried out using tone bursts and a novel broadband transient source [G. Kaduchak, Ph.D. dissertation, WSU (1994)]. Ray theory pertaining to some of the underlying features observed will be discussed including: (a) a bipolar specular feature of the impulse response sensitive to the shell’s mass-per-area; (b) a high-frequency enhancement of the tone burst response due to a backwards wave [G. Kaduchak etal., J. Acoust. Soc. Am. (in press)]; (c) the coincidence frequency enhancement of the tone burst and impulse responses associated with the a0− wave; (d) low-frequency features evident in the impulse response associated with the effect of curvature on the a0− wave (or what some authors describe as the ‘‘Junger wave’’); and (e) periodic s0 wave packets giving resonance dips up to moderate frequencies. Feature (b) is sometimes called the thickness quasiresonance and for the stainless steel shell studied the ray theory uses the s2 leaky Lamb wave properties in the negative group-velocity region. The development of ray theory for situations where conventional thin shell theory is not applicable will be reviewed. [Work supported by ONR.]
Implementation of a ray tracing algorithm to calculate the acoustic scattering from fluid loaded, doubly curved shells
Authors: Rebinsky Douglas A. , Norris Andrew N. , Yang Yang
Published: October 2005

Ray tracing is used to calculate the acoustical and structural response of smooth, elastic shells of nonseparable shape. The frequency range of interest is below flexural coincidence but still high enough that asymptotic methods are applicable. The structure and development of ray-like solutions on arbitrarily doubly curved shells is reviewed with a discussion of two mechanisms: (1) a ‘‘background’’ response determined by the local inertial impedance, and (2) phase matching to longitudinal and shear waves. The background response can be approximated by specular reflection, but the membrane waves require global treatment over the whole structure. After first calculating the coupling curves, which are the closed loci defined by phase matching with the incident wavefield, ‘‘pressure’’ rays are then sent out over the shell with each ray and its amplitude evolving according to a ray equation and a transport equation. Illustrative examples of ray paths and ray-tube areas will be presented for ellipsoidal and quasicylindrical shells. The use of the Gaussian beam summation method to describe the wavefields will be discussed. Numerical comparisons are made with the exact results for the canonical geometries, and extensions to nonseparable shapes and discontinuous shells will be shown and discussed. [Work supported by ONR.]