bluuebunny/crossref_metadata_2025 huggingface dataset:
Acoustic-perceptual factors in nasal place assimilation.
Authors: Speeter Beddor Patrice , Evans-Romaine David K.
Published: October 2005

Phonologically, nasal consonants often assimilate to the place of a following oral stop. While the source of this assimilation is generally taken to be anticipatory coarticulation, this study examines the possibility that acoustic-perceptual factors are partially or even primarily responsible. Two American English speakers produced /zV́NCschwa/ tokens (V=/i/, /æ/, /schwa /;NC=/mb/, /nd/, /hooked en g/). Stimuli were split into /zVN/ and /Cschwa/ portions. /zVN/ portions whose final N was identified with at least 97% accuracy (four judges) were cross-spliced with /Cschwa/ portions to yield all possible N–C pairings. Listeners identified N and C of the cross-spliced /zV́NCschwa/ stimuli. Homorganic clusters were correctly identified 95% of the time (preliminary results with eight listeners). Listeners varied in accuracy of N identification in nonhomorganic clusters, but across subjects one-third of nonhomorganic nasals were misidentified, with homorganic responses comprising 80% of these errors. Although different places of articulation showed different response patterns, overall results indicate that place cues for nasals may be overridden by those of a following oral stop. Even nasals whose place is unambiguous in final position may shift perceptually before heterosyllabic oral stops.
The role of allophonic variation in the perception of the junctural position of /l/.
Authors: Dutton Dawn L.
Published: October 2005

Many theories of spoken word recognition assume speech is segmented at syllable or word boundaries prior to contact with the lexicon. A number of researchers [see K. W. Church, Cognition 25, 53–69 (1987)] have observed systematic acoustic differences (or allophonic variations) within a phonetic class that may serve as cues to juncture points between syllables or words. The most common difference cited between syllable initial and syllable final /l/ is the proximity of the first two formants. Some researchers have also noted a difference in the amplitude profile of /l/ depending on its position relative to a word boundary. In this experiment, two starting phrases, ‘‘see leaves’’ and ‘‘seal eaves,’’ were synthesized. F1 frequency profile, F2 frequency profile, and amplitude profile were varied orthogonally for both starting phrases. The junctural position of /l/ was cued primarily by F1 frequency profile. F2 frequency profile, and thus the proximity of the first two formants, and amplitude profile seemed to play a very small role in the perception of /l/ position. [Work supported by NIDCD Grant No. DC 00219 to SUNY at Buffalo.]
Application of the Sommerfeld–Watson transformation to scattering of acoustic waves obliquely incident upon cylindrical shells
Authors: Rumerman M. L.
Published: October 2005

The Sommerfeld–Watson transformation (SWT) is applied to the normal mode series for scattering of an obliquely incident plane acoustic wave from an infinite circularly cylindrical shell to express the scattered field in terms of its wave components. The ‘‘geometric’’ part of the scattered field is extracted and expressed as a line integral that is evaluated by shifting to a path of steepest descent (SDP). When deforming the path, one or more poles may be crossed and their residues must be accounted for, resulting in discontinuities in the computed field unless the effects of these poles are also included in the evaluation of the SDP integral. This correction, made in the analysis in this paper, is applied to the particular example of a thin steel shell in water, using thin-shell theory. Very good agreement for scattering into the backward half-space is obtained between the results of the normal mode series and the modified SWT calculation for frequency-angle combinations such that ka cos φ≥2, where φ is the angle of incidence of the plane wave relative to the shell normal. Inclusion of the corrections to the solution also improves the calculation even when no poles are crossed by the path deformation.
Fermi–Pasta–Ulam recurrence of bound solitary waves in a rectangular water trough
Authors: Xu Y. , Wei R.
Published: October 2005

The solution of bound solitary waves of a NLS-type equation governing the modulational evolution of standing gravity wave in a rectangular fluid trough is given. It is seen that the time evolution of this solution exhibits the Fermi–Pasta–Ulam (FPU) recurrence behavior that is in good agreement with the phenomenon observed by Wu et al. [Phys. Rev. Lett. 52, 1421–1424 (1984)] in a water trough experiment.
Computation of acoustic scattering from a moving rigid surface
Authors: Myers M. K. , Hausmann J. S.
Published: October 2005

Application of the Kirchhoff formula for subsonically moving surfaces to scattering of sound from a moving rigid body is described. The formulation leads to a singular integral equation that yields surface values of the field. The integral equation is solved using a boundary element technique in conjunction with the Galerkin method. Several checks on the accuracy and validity of the scheme are discussed. Numerical results are obtained for scattering of sound from a harmonic point source co-moving with a thin, winglike body.
A physically motivated simulation technique for high-frequency forward scattering derived using specular point theory
Authors: Funk Dale E. , Williams Kevin L.
Published: October 2005

A physically motivated simulation technique using specular point theory (SPT) is developed to examine high-frequency signals forward scattered from a rough surface. This method is used to derive, for small receiver separations, the spatial coherence for an infinite ensemble of signals forward scattered from random surfaces with Gaussian wave-number spectra. The results are compared with those of previously published methods. An SPT single realization procedure is formulated and implemented for frequencies of 30 and 300 kHz using a Gaussian spectrum approximation to the random rough surface. Some SPT predictions for Gaussian and Pierson–Moskowitz surfaces are compared. Both the spatial coherence and the temporal structure of finite ensembles of forward scattered signals are compared for the Gaussian case. The relation between the results for infinite and finite ensembles is then examined, and the practical implications and limitations of SPT for simulating forward scattering are discussed.
Effects of place of articulation and vocalic context on the perception of VOT continua in French and English.
Authors: Nearey Terrance M. , Rochet Bernard L.
Published: October 2005

Previous findings indicate that VOT varies in production with place of articulation and with following vowel, though details differ somewhat in French and English. Here, perceptual results are presented involving VOT continua ranging from −80 to +80 ms VOT in 10-ms steps. Twelve different continua were constructed (three places of articulation by four vowels). Seven English and six French speakers categorized these continua as /b,d,g,p,t,k/ and simultaneously provided ‘‘goodness’’ ratings. Voiced–voiceless crossover boundaries for English speakers showed highly significant main effects and interactions for both factors. Differences among the French speakers were not significant. The ‘‘goodness’’ rating data of the French speakers, however, did show significant effects for place, but none for vowel context. Although vowel effects in this production data are about twice as large in French as in English, French listeners show less evidence of sensitivity to vowel context. Possible reasons for this lack of parallelism will be discussed. [Work supported by SSHRC.]
Use of vocalic cues to final consonant voicing in perception and production of English CVC’s by native speakers of Arabic.
Authors: Crowther Court , Mann Virginia
Published: October 2005

Native Arabic speakers who were either late learners (first resided in an English speaking country after high school) or early learners (first resided during high school) were compared in two experiments that tested their use of vocalic duration and F1 offset frequency as final consonant voicing cues in the English CVC’s ‘‘pod’’ and ‘‘pot.’’ Experiment 1 measured both vocalic duration and F1 offset frequency of subjects’ productions of these syllables; and experiment 2 considered their perception of tokens from synthetic ‘‘pod’’–‘‘pot’’ continua that varied vocalic duration and F1 offset. The results indicate some effects of native language experience and age of learning. Use of vocalic duration in production was greater for early than late learners, although considerably smaller than that of native English speakers. The early learners showed native-like sensitivity to vocalic duration as a voicing cue, but the late learners did not. The range of F1 offset frequency differences tended to be smaller than in native productions, and to show less effect of voicing. However, both nonnative groups showed native-like sensitivity to F1 offset.
Acoustic properties contributing to the classification of place of articulation for stops.
Authors: Ananthapadmanabha T. V. , Stevens Kenneth N.
Published: October 2005

The production of stop consonants generates several kinds of acoustic properties: (i) the spectrum of the initial transient and burst indicating the size of the cavity anterior to the constriction; (ii) place-dependent articulatory dynamics leading to different time courses of the noise burst, onset of glottal vibrations and formant transitions; (iii) formant transitions indicating the changing vocal tract shape from the closed position of the stop to a more open configuration of the following vowel. The interest in this study is to measure the relative contributions of these acoustic properties to the classification of the consonantal place of articulation using a semi-automatic procedure. The acoustic data consisted of a number of repetitions of voiceless unaspirated stops in meaningful words spoken by several female and male speakers. The spectra averaged over the stop release and at the vowel onset were used as the acoustic feature. Speaker-independent and vowel-independent classification was about 80% using either the burst or vowel onset spectrum and a combined strategy led to a higher accuracy. Studies with additional acoustic properties that relate to articulatory dynamics, such as VOT and formant transitions, are planned.
An analysis of invariance in English stop consonants.
Authors: Richardson Kevin H.
Published: October 2005

Speech researchers have been attempting to isolate acoustic invariance in the speech signal for the past several decades. Currently, however, no conception of invariance has proven adequate to the task of demonstrating the existence of invariant acoustic features in the six English stop consonants. In the present study, static and dynamic versions of two recent invariance proposals [Sawusch and Dutton (in press) and Forrest, Weismer, Milenkovic, and Dougall (1988)] were developed and tested on a corpus of 1392 naturally produced stop and stop consonant cluster tokens. Classification accuracies of the metrics using stepwise discriminant analyses showed performance to be significantly different from chance but lower than expected had the metrics isolated invariance in the signal. Results will be discussed in terms of general human auditory-phonetic coding ability. Also, the notion that invariant acoustic features are the most useful way of conceptualizing the problem of phoneme recognition will be questioned. [Work supported by NIDCD Grant No. R01-DC00219 to SUNY at Buffalo.]
Acoustic property measurement of ultrasonic delay line.
Authors: Wang Yinguan
Published: October 2005

The acoustic properties of F05 ultrasonic delay-line glass produced by the Shanghai Xin-Fu Glass Factory are measured with an instrument built by this institute. The instrument can automatically and continuously measure a small variation of ultrasonic velocity by a pulse superposition (PS) method with a solution of 2×10−7; precisely measure absolute ultrasonic velocity by a pulse echo overlap (PEO) method with a precision of 1×10−4; and automatically and continuously measure ultrasonic attenuation by a gated echoes comparison (GEC) method with a resolution of 0.1 dB. Three parts in one instrument not only can possess the advantage of convenience, but also can overcome the shortage of determining the absolute value by the PS method. The absolute velocity of longitudinal wave in the F05 delay line is 4140 (m/s) (all at 20 °C), temperature coefficient of travel time is −3.3×10−5/°C, attenuation coefficient is 0.12+0.02 (dB/cm), and temperature coefficient of attentuation is 2.5×10−3/°C. The absolute velocity of a transverse wave in the F05 delay line is 2524 (m/s), the temperature coefficient of travel time is −4.5×10−6/°C, attenuation coefficient is 2.4+0.04 (dB/cm), the temperature coefficient of attenuation is 6×10−3/°C.
Investigation of scattering with acoustic holography.
Authors: Cheng Ming-Te , Pate Anna L. , Groutage Dayle
Published: October 2005

The objective of this paper is to investigate sound scattering of a rigid sphere using the acoustic holography method. A piston source, which is vibrating sinusoidally, illuminates a sphere. The superimposed incident and scattered fields are measured in the near field of the sphere using acoustic holography. These two fields are decomposed in the wave-vector domain and, therefore, the scattered field is extracted. Numerical simulations are performed and the effect of various parameters is investigated. Specifically, the distance between two holography planes, the sampling rate, and the aperture size are investigated in the field separation technique. In addition, experimental studies were conducted inside an anechoic chamber with a baffled loudspeaker as a source and a cast-iron sphere as a scatterer. The experiments demonstrate the feasibility of the field separation technique based on two-plane acoustic holography. [Work supported by David Taylor Research Center.]
The determination of the relative strengths of resonances excited for plane waves scattered from elastic spheroids.
Authors: Dean C. E. , Werby M. F. , White Elmer
Published: October 2005

Calculations are presented for scattering from spheroids composed of six materials for aspect ratios of 3 and 6. The difference in resonance locations is noted as a function of material properties and the differences can be explained in terms of pseudo-Rayleigh type resonances described extensively in the literature for spheroids. There is also a marked difference between the amplitudes of the resonances. It is possible to predict the relative amplitudes of the resonances as a function of material properties based also on the Rayleigh wave interpretation of these resonances. A theory is developed based on the fact that Rayleigh type resonances can only be excited as a function of the appropriate grazing angular region. This region is determined as a function of the material property and geometry. The theory accounts for the numerical predictions nicely. Numerous results are presented.
The manifestation of certain classes of resonances as standing waves on elastic spheroidal objects.
Authors: Werby M. F. , Dean C. E. , White Elmer
Published: October 2005

In an earlier work it has been shown that certain classes of resonances excited on elastic spherical solids correspond to standing wave patterns on the object surface. This observation was in fact implicit in the circumferential nature of such resonances. The demonstration was made possible by subtracting the rigid background and plotting the bistatic angular distributions in the asymptotic limit resulting in a standing wave pattern. For the spheroidal case it is more difficult to demonstrate this affect in the asymptotic limit since typically the asymptotic limit implies spherical symmetry that is not adhered to for spheroids. It is possible to demonstrate that this is also observed for resonances on spheroids by choosing a spheroidal surface and plotting the results once the rigid background is subtracted. It is also possible to observe the results by projecting the asymptotic results on to a spheroidal basis. Results are presented for several examples.
Signatures from pulse signals scattered from elongated elastic solids.
Authors: White Elmer , Werby M. F. , Dean C. E.
Published: October 2005

Time domain signals can manifest characteristic signals when the mid-pulse frequency is in some resonance region. This work attempts to determine unique signals characteristic of pulse scattering at frequencies associated with resonances excited from elongated targets. In an earlier work beat patterns and damped sinusoidal patterns (as a function of time) were associated with single or specific clusters of resonances. Here, damped sinusoidal patterns are associated with specific resonances in which it is shown how to extract specific resonance widths that are shown to be associated with three classes of resonances excited from elastic spheroids. This includes resonances excited broadside, end-on, and at oblique incident angles. Also determined are some beat patterns from some types of resonance clustering.
Measurement of periodic surface backscattering to high diffractive order.
Authors: Suiter H. R.
Published: October 2005

New tank measurements have been done of the backscattering from two periods each of a pressure release sine wave, Stokes wave, and wedge profile grating from about 60 to 200 kHz. The rms surface deviation of all six targets was selected to be approximately the same value at 2.3 mm. The measurements were done beyond the fifth diffraction order, and in one case, to the eighth order using a new technique. Dispersion curves were followed almost exactly except for some anomalous dispersion attributed to Wood P-type anomalies. Comparison of reflection coefficients is made to a modified Kirchhoff scattering model that takes into account the bounded nature of the beam. Agreement is good. [Work supported by ONR.]
A comparative approach to the nonhuman primate vocal tract: Implications for sound production.
Authors: Ybarra Miguel A. Schoen
Published: October 2005

This talk aims at elucidating the sound-producing capabilities inherent to the nonhuman primate vocal tract morphology. Focus is on tract features which, on the bases of their respective form, structure, and location, can be regarded as (1) capable of contributing to generate a voiced/unvoiced source function, or (2) to transiently modify the transfer function of the tract. Relevant qualitative data, and, whenever accessible, also quantitative, were obtained from current references, and in the laboratory of the speaker where morphology-to-performance relationships are being studied in the vocal tract of the rhesus macaque and some New World monkeys. Comparative considerations suggest that the vocal tract of nonhuman primates can produce a variety of sounds and sound contrasts common to all nonhuman primates, but, also, that some of the taxa can make certain sounds and sound contrasts which others cannot.
Neuroethological approaches to the study of vocal production in nonhuman primates.
Authors: Newman John D.
Published: October 2005

The vocalizations of nonhuman primates are potentially important probes for studying the neural and neurochemical substrates of behavior. These studies have focused on one category of vocalization, the isolation call, due to its relatively stereotyped acoustic structure and ease of elicitation and attribution in captive animals. Experimental brain lesions reveal an important role for the thalamic tegmentum and anterior cingulate gyrus in mediating normal acoustic structure and motivation to vocalize, respectively. The amygdala plays a role in determining the development of normal levels of emotional expression, as shown in the effects of neonatal ablations of this limbic structure and its cortical afferents on vocal behavior during development. Neurochemical control of the isolation call arises from several disparate endogenous neurochemical systems, including opiatergic and monoaminergic pathways.
The role of articulation in the production of nonhuman primate vocalizations.
Authors: Hauser Marc D.
Published: October 2005

Observational and experimental data on rhesus monkeys are presented that demonstrate that changes in articulation, especially movements of the lips and mandible, have a direct influence on the resonance properties of the call, independently of changes in the fundamental frequency. These data suggest that the source-filter theory of sound production is also applicable to nonhuman primates. In the second part of the presentation, results are discussed from experiments that examined the ability of rhesus monkeys to compensate for novel vocal tract perturbations. In particular, having demonstrated that the lips play a role in sound production under natural conditions, acoustic analyses of the vocalizations produced by animals whose lips were temporarily paralyzed through the administration of lidocaine were conducted. Results showed that for some vocalizations, lidocaine failed to cause detectable changes in acoustic morphology whereas for other vocalizations, which appeared to involve more fine-grained manipulations of lip configuration, there were noticeable acoustic consequences. Together, these results suggest that nonhuman primates have significantly greater articulatory freedom than heretofore predicted.
Are primate vocalizations adapted to the local habitat?
Authors: Brown Charles H. , Gomez Rafael , Waser Peter M.
Published: October 2005

Twenty-one representative vocalizations of two species of rain forest monkeys [blue monkeys (Cercopithecusmitis) and grey-cheeked mangabeys (Cercocebusalbigena)], and two species of savanna monkeys [vervet monkeys (C. aethiops) and yellow baboons (Papiocynocephalus)] were broadcast and re-recorded in both the ‘‘appropriate’’ and ‘‘inappropriate’’ habitat in Kenya. The re-recorded signals were digitized and distortion analyses were conducted with signal processing routines on a Cray XMP-24 supercomputer. Rain forest monkey calls were distorted less in the ‘‘appropriate’’ rain forest habitat than in the ‘‘inappropriate’’ savanna habitat, but the converse did not hold for savanna monkey calls. Savanna monkey calls were distorted the same amount in both habitats (time domain analysis), or were distorted slightly less by the rain forest habitat (frequency domain analysis). The results suggest that the rain forest is more favorable than the savanna for high-fidelity sound propagation, and, in addition, rain forest monkey calls appear better ‘‘designed’’ than savanna monkey calls to reduce the probability of distortion by the acoustics of the local habitat. [Work supported by NIDCD.]
Quantitative aspects of acoustic emission in theory and practice.
Authors: Friesel Mark A.
Published: October 2005

Acoustic emissions are known for their sensitivity to conditions of the sources, propagating media, and detection instrumentation. The concurrent ease of use of this technology for nondestructive evaluation has helped foster the notion that acoustic emission techniques are incurably qualitative by nature. Recent theoretical developments and use of modern signal processing and analysis techniques, however, show that acoustic emissions are rich sources of quantitative information about active microscopic damage and other processes. After discussion of the current state of acoustic emission theory, the characteristics of certain data types will be examined. The results obtained by applying various signal processing methods to acoustic emission data are presented.
Acoustic scattering from fluid turbulence.
Authors: Goodman Louis , Szargowicz Diane , Oeschger John , O’Donnell Michelle
Published: October 2005

There has been considerable interest in the oceanographic community in whether it is possible to use high-frequency acoustic echo sounders to measure ocean microstructure. A laboratory program, the ocean acoustics turbulence study (OATS), has been developed to examine the nature of such scattering and to compare results with that of a model recently proposed by Goodman (1990). The fundamental theory underlying the model is Bragg scattering, which results in the scattered pressure field proportional to the Fourier transform of the temperature field. A small heating element is used to generate a buoyant turbulent plume. Such a relationship could allow the prediction of the three-dimensional turbulent wave-number spectrum provided a sufficiently wide dynamic range in Bragg wave-number space were measurable. By performing scattering experiments over a very wide range of angles (ϑ=5° to ϑ=160°) and frequencies (250 kHz to 1.4 MHz) it is possible to infer such a composite spectrum. Preliminary results indicate a turbulent wave-number spectrum of classical form (−11/3 power law) in agreement with that expected for a fully developed turbulent field.
Some aspects of wavelet transform in biosonar signal processing and detection.
Authors: Lin Zhen-Biao
Published: October 2005

Wavelet transform (WT) provides multiresolution at different frequencies. The concept of WT is related to the constant Q filter bank in modeling of cochlea, and is therefore suitable for the study of auditory signal processing in bats. The results from FM bat signal analysis show that FM bat signals consist of a number of scaled basic prototype (wavelets): from a low-frequency component with long duration to a high-frequency component with short duration or large bandwidth. For example, the signals in the search phase, which tunes in time-frequency resolution, allow the bat to extract diverse target information at different frequencies, global information (motion) at low frequency and distance information at high frequency. The bat’s signals in terminal phase consist of 2nd and 3rd harmonics in a fraction of duration of 0.2–0.5 ms. Therefore an insect’s precise location may be obtained at these harmonic frequencies. In a case where the bat-emitted signal is selected as the basic prototype of wavelet, the WT becomes a version of the wideband ambiguity function. Two dozen signals emitted by an FM bat, Pipistrellus, during natural hunting of insects were recorded and analyzed with WT and Wigner distribution (WD). Two-dimensional delay scalograms and two-dimensional time spectrums in different hunting phases are given. The strong link between WD and WT is used to explore the strategies of echolocation signals adopted to diverse tasks. The Doppler tolerant waveform is a special selection of wavelet basic prototype, such that all ‘‘wavelets’’ have the same version as that of the prototype.
Development of synthesis-analysis tools for a computer-based course in acoustic phonetics.
Authors: Berkovitz Robert , Pickett J. M. , Williams David
Published: October 2005

Decreasing prices of personal computers and signal-processing boards permit the widespread use of computer-based instruction in acoustic phonetics. Software already developed for the Sensimetrics SpeechStation provides simplified speech synthesis and convenient spectral analysis displays. Synthesis exercises in which the student controls a vocal tract diagram are being developed to teach the principles of relations between articulatory configurations and speech sounds. SpeechStation analysis facilities will provide correlated displays of spectra of synthetic or natural utterances. Initial plans are to develop a complete introductory course of 16 lessons. Course material for advanced students would serve to train in research methods and teach advanced topics. A trial lesson will be demonstrated. [Work supported by NIDOCD.]
Project Oracle: Software for training in speech science.
Authors: Seikel J. Anthony , Drumright David G.
Published: October 2005

Project Oracle was instituted to develop public domain software and laboratory activities that would give students in the speech and hearing sciences the opportunity to explore speech and nonspeech acoustics in a nonthreatening environment. Waveform editing software and lab activities were developed for speech science and phonetics courses and introduced into the curriculum. The presentation will provide examples of lab activities, hands-on demonstration of the waveform editing, FFT, and phonetics transcription training software, as well as results of software implementation. [Work supported by Dept. of Education, FIPSE.]
Waveform editing and spectrographic software.
Authors: Neely Stephen T. , Nittrouer Susan , Carney Edward J.
Published: October 2005

Programs for interactive editing and spectrographic display of digitized speech waveform files have been developed for use on IBM-PC compatible computers. The waveform editing program (WavEd) reads and writes waveform files of several types, including ILS sampled data. WavEd allows the user to perform the following operations: (1) record and play waveforms; (2) place labels at various points, and save these labels; (3) copy, delete, and insert waveform segments; and (4) do acoustic analyses, such as computation of durations, formant frequencies and bandwidths, and linear prediction coefficients. The spectrographic display program (SPECTO) produces spectrograms from ILS sampled data files using filters of user-specified bandwidths. Parameters that determine spectrogram appearance (such as darkness, contrast, and frequency and time range) are user controlled. Spectrograms can be sent to the PC monitor or to dot-matrix or laser printers. Both programs are designed to be easy to install and to use on any PC, with either a commercial digital-to-analog converter or the PC-internal speaker. Both programs are being distributed as unsupported software and nonprofit redistribution is permitted. [Work supported by NIH.]
Intrinsic attenuation and scattering in laterally inhomogeneous sediments.
Authors: Stephen R. A.
Published: October 2005

Intrinsic attenuation represents energy lost from the acoustic field through internal friction. Scattering represents energy lost from a particular coherent path either to another coherent path (as in compressional to shear wave conversion) or to incoherent energy (e.g., angle spread, time spread, or coda). Nothing can be done with energy lost to intrinsic attenuation. However, in the case of multiple coherent paths processing could be carried out to optimize the total energy on all paths. In the case of incoherent scattering there is an increase in the ‘‘noise’’ floor due to the source (source-generated noise) that will yield an upper bound on the signal-to-noise ratio independent of the true ambient noise. All three contributions to ‘‘effective’’ attenuation will have different frequency dependence and the relative importance of each mechanism will depend on the environment. In order to thoroughly understand the observed geoacoustic field in marine sediments it is necessary to distinguish between these effects. A propagation modeling code has been developed, based on the method of finite differences, which incorporates intrinsic attenuation. The same code can treat scattering from volume heterogeneities and surface roughness for structures with scale lengths comparable to acoustic wavelengths. All propagation effects including shear waves, interface waves, two-way propagation, and multiple interactions between scatterers are considered. The first problem that will be addressed with this code is the effect of intrinsic attenuation on the coda (time spread) caused by scattering from volume heterogeneities in sediments. [Work supported by ONR.]
The measurement of modal evolution in a range-dependent, shallow-water waveguide.
Authors: Frisk George V. , Ohta Kazuhiko , Rajan Subramaniam D. , Doutt James A.
Published: October 2005

A technique is described for the measurement of normal mode eigenvalues as a function of range in a laterally inhomogeneous, shallow-water waveguide. It is based on the notion, originating in adiabatic mode theory, that the local modes adapt to the local environment. The trajectories of the eigenvalues in range are therefore influenced by lateral variations in the geoacoustic parameters of the seabed as well as bathymetric changes and fluctuations in the acoustic properties of the water column. Knowledge of the modal evolution in a waveguide plays a critical role in characterizing sound propagation and its relationship to the environment in shallow water. The method consists of beamforming narrow-band pressure field data acquired on a horizontal array using a short sliding aperture in range and examining the trajectories of the modal peaks in the beamformed output. The modal resolution can be significantly enhanced by mode filtering with a vertical array of receivers prior to the beamforming operation. Applications to synthetic and experimental data are discussed. [Work supported by ONR.]
Shear wave transducer for ocean sediment applications.
Authors: Walden Alan K. , Howarth Thomas R.
Published: October 2005

A low-frequency shear wave transducer has been developed for ocean geoacoustic applications. The transducer generates and receives torsional shear waves for increased energy propagation. The design is a lightweight structure with a hollow cylinder sandwiched between two radiating disks to form a spool-shaped geometry. The interior and exterior are encapsulated with a soft polymer filler. Piezoelectric ceramics are mounted on the cylinder and configured to excite the ‘‘1–5’’ mode of the piezoceramic during operation. The radiating disks are designed to ‘‘pull’’ the encapsulant medium such that they introduce a torsional shear wave through the encapsulant and into the sediment medium. Low-frequency operation is ensured through the proper selection of the structure’s dimensions and materials. The design suggests that performance will be improved as the hydrostatic pressure is increased.
Spectral parabolic equation solutions of three-dimensional problems involving horizontal coupling and backscattering.
Authors: Orris G. J. , Collins Michael D. , Kuperman W. A.
Published: October 2005

The parabolic equation (PE) method and separation of variables are applied to solve problems in which the ocean-acoustic parameters are independent of one of the horizontal Cartesian coordinates. This class of problems is representative of backscattering from ridgelike seamounts, horizontal coupling out of the radial direction, and other types of reverberation. Since the PE method efficiently handles nearly arbitrary variations in depth and in the other horizontal direction, it is possible and practical to solve complicated three-dimensional problems with this approach. The two-way PE is applied to backscattering problems. Solutions are compared with three-dimensional PE solutions for problems involving horizontal coupling. Problems involving elastic ocean bottoms are also considered.
Nonlinear inversion of sediment parameters in a range-dependent region of the Gulf of Mexico.
Authors: Collins Michael D. , Kuperman W. A. , Schmidt Henrik
Published: October 2005

A set of acoustic data was taken in the Gulf of Mexico and used to invert sediment properties by Lynch etal. [J. Acoust. Soc. Am. 89, 648–665 (1991)]. Using a linear optimization method and a range-independent propagation model, they obtained sediment parameters that result in fairly good agreement between the measured and theoretical transmission loss (TL) curves. Since the data are for a long synthetic-aperture horizontal array, it is ideal for range-dependent inversion. Using simulated annealing for nonlinear optimization and the parabolic equation method for range-dependent propagation, sediment parameters have been obtained that result in excellent agreement between the measured and theoretical TL curves. The range dependence of the depth of the interface between the upper and lower sediment layers was determined to be a particularly important parameter.
The role of experience in nonhuman primate vocal development.
Authors: Owren Michael J.
Published: October 2005

In contrast to the extensive evidence of plasticity in avian and human vocal development, studies in nonhuman primates present a conflicting picture of the normal course of vocal ontogeny. Evidence from squirrel monkeys (Saimirisciureus) indicates that calls emerge fully formed at an early point and that little or no modification of calling behavior occurs. Investigations involving Old World monkeys have produced evidence of modifiability in both signal form and use. However, none of these studies have directly shown the necessity of particular experiences for the emergence of species-typical vocal behavior. Two recent experiments have sought direct evidence through cross-fostering of infant rhesus (Macacamulatta) and Japanese (M. fuscata) macaques between species, but have provided inconsistent results. Overall, the evidence continues to indicate that experience plays a comparatively limited role in nonhuman primate vocal ontogeny. [Work supported by NIH.]
An evaluation of the role of envelope-based cues for the detection of a tone added to noise.
Authors: Richards Virginia M. , Nekrich Robert D.
Published: October 2005

Using 2IFC paradigm, d’ scores were obtained for two conditions derived from the tone-in-noise task. In one condition, observers detected a tone added to a band of noise, but the waveforms presented in the two intervals were of equal energy. Noise center frequencies and signal frequencies of 600, 1800, and 5400 Hz and noise bandwidths of 40, 120, and 360 Hz were used. In the second condition, the envelopes of the noise-alone and tone-plus-noise waveforms were extracted, and the envelopes were used to modulate sinusoids of 600, 1800, and 5400 Hz. The observers’ ability to discriminate between modulation patterns was measured. For narrow bands of noise, d’ values in the two conditions were approximately equal, indicating that for level-equalized waveforms the detectability of a tone added to noise could be accounted for by differences in the envelope patterns. For bandwidths that were larger than or equal to 20% of the center frequency, d’ scores obtained using amplitude modulated tones were superior to those obtained using the level-equalized stimuli, an advantage that may reflect differences in the power spectra of the modulated tones. [Supported by the NIH.]
Across-frequency processing of multiple modulation patterns.
Authors: Grose J. H. , Hall J. W.
Published: October 2005

In a study linking comodulation masking release (CMR) and auditory grouping, it was demonstrated that the auditory system is capable of performing a CMR using one modulation pattern while a second modulation pattern is simultaneously present [J. W. Hall and J. H. Grose, J. Acoust. Soc. Am. 88, 119–125 (1990)]. This study proceeds to examine whether the auditory system can perform a CMR on a complex signal that is jointly masked by separate modulation patterns; i.e., can the auditory system perform a CMR using each of two concurrent modulation patterns? The signal was a two-tone complex (618 and 1400 Hz). The composite backgrounds were composed of narrow bands of noise whose center frequencies were harmonics of either 103 or 175 Hz. Various noiseband configurations were constructed to result in modulation patterns that were either adjacent, interspersed, or completely uncorrelated across bands. Results to date indicate that thresholds are markedly lower in conditions where the noisebands form two adjacent regions of comodulation relative to conditions where the bands are uncorrelated. CMR is reduced when the modulation patterns are interspersed. [Work supported by the Deafness Research Foundation.]
Masking period patterns in normal-hearing and hearing-impaired listeners.
Authors: Schroder Anna C. , Nelson David A.
Published: October 2005

Masking period patterns (MPPs), developed by Zwicker [J. Acoust. Soc. Am. 59, 166–175 (1976)] as a psychophysical correlate of the physiological period histogram, were obtained from four normal-hearing and four cochlear hearing-impaired subjects. The just audible level of a brief, relatively high-frequency, test tone was measured as a function of its temporal position within the period of a 40-Hz masker. Zwicker’s findings were replicated in normal listeners. At low masker levels a single maximum (Max 1) was observed between 0 and 90 deg of the masker period. At higher masker levels a second maximum (Max 2) developed between 180 and 270 deg. Zwicker’s model [Biol. Cyb. 23, 49–60 (1976)] suggests that Max 1 reflects level-independent suppression effects and Max 2 reflects some combination of level-dependent excitation and suppression effects, which is consistent with physiological biasing data. For impaired listeners, in regions of hearing loss, the degree of modulation in the MPP was reduced relative to that seen in normal-hearing listeners. The pattern of modulation was usually altered as well. These results are discussed in the context of outer hair cell damage at the place in the cochlea corresponding to the test tone frequency. [Supported by NIDCD.]
Educational issues in speech communication.
Authors: Tobey Emily A. , Strange Winifred , Stone Maureen , Stevens Ken , Ladefoged Peter
Published: October 2005

The Speech Communication Technical Committee has formed a subcommittee to investigate educational issues related to the instruction of speech acoustics. The Education Subcommittee is initially focusing their efforts on core issues that cut across the different disciplines represented in Speech Communication. The purpose of this report is to share the findings of a recent questionnaire sent to the Speech Communication and Psychological and Physiological Acoustics membership. Data will be reported on the scope of acoustic training, the common acoustic topics taught across disciplines, the types of software used to teach speech acoustics, the type of textbooks used, the type of handouts used to augment lectures, the type of video/audio materials used as demonstrations, and the type of laboratory experiences available to students. In addition, this presentation will review the types of laboratory equipment used to train students in basic and speech acoustics.
Measurement and control of noise from small arms firing facilities.
Authors: Brooks Bennett M.
Published: October 2005

Noise due to small arms fire can have a significant impact, both to participants and on the surrounding community, causing considerable annoyance if not controlled. Measurement techniques must allow for the accurate capture of these high-energy impulses, particularly when regulatory forces are involved. Using these test data, control strategies employing progressively more effective means may be developed. In this paper, measured noise data from several small arms firing facilities are presented, including the firing range of a major arms manufacturer. Noise control methods and the results of their application are discussed.
A numerical model for the propagation of sonic booms through an inhomogeneous, windy atmosphere.
Authors: Robinson Leick
Published: October 2005

The ZEPHYRUS computer model has been developed to calculate sonic boom propagation through a realistic atmosphere. This model includes the effects of (1) nonlinear distortion (weak shock theory), (2) attenuation and dispersion due to thermoviscous effects and oxygen and nitrogen molecular relaxation, and (3) an inhomogeneous, stratified atmosphere with a stratified wind field. Propagation through reflections and weak (linelike) caustics are included. Analysis of the stability of shocks shows that the characteristic formation distance for stable shocks may be greater than previously believed. In general, stable shocks have not formed when the sonic boom reaches the ground. Also, the rise time has been demonstrated to have a strong dependence on the waveform shape immediately behind the lead shock. Investigations have revealed an interesting phenomenon in which the rise time displays a second peak at the midlevel altitudes, both before and after reflection. This is apparently due to the dispersion from oxygen molecular relaxation when the characteristic relaxation time closely matches the lead shock rise time. [Work supported by NASA and ARL-UT IR&D program.]
Application of a modified NPE model to the prediction of sonic boom waveforms.
Authors: Piacsek Andrew A. , Pierce Allan D.
Published: October 2005

The nonlinear progressive wave equation (NPE) model, developed by McDonald and Kuperman [J. Acoust. Soc. Am. 81, 1406–1417 (1987)] has been adapted for atmospheric propagation in order to model the effect of turbulence on the shape of sonic boom profiles. As a test of the efficacy of this adaption, the program was run with a relatively simple scenario conceived in a theoretical analysis by Pierce [J. Acoust. Soc. Am. 44, 1052 (1968)]. In that paper, spiked and rounded variations of N-wave shock profiles were shown to result from focusing and defocusing, respectively, of an initially rippled wave front propagating in a homogeneous medium. The acoustic pressure versus time profiles generated by the NPE are compared to those predicted by Pierce. Specific improvements and modifications to the NPE are discussed, as well as the intended use of the model to simulate propagation of N waves through an inhomogeneous medium. [Work supported by NASA.]
Application of similarity theory for calculating the acoustic refractive index structure parameter.
Authors: Noble John M.
Published: October 2005

The acoustic refractive index structure parameter is important for determining the strength of atmospheric turbulence. The current methods for calculating the acoustic refractive index structure parameter is to calculate the temperature and wind structure parameter from tedious hot-wire anemometer measurements. Also most methods only provide a measurement of the turbulence strength at one height. An alternative method to calculate the refractive index structure parameter is to calculate the temperature and wind structure parameters using similarity theory. The similarity model requires easily obtained meteorological data at one height along with an estimate of the roughness length. The model uses similarity theory to calculate the temperature and wind structure parameters with height. This provides the capability to calculate the refractive index structure parameter with height. A comparison with turbulence data [Johnson etal., J. Acoust. Soc. Am. 81, 638–646 (1987)] will show how well the model works. This type of model predicts the turbulence strength with height through the surface layer for different stability states of the atmosphere.
A fast-field algorithm for sound propagation in layered media using a two-dimensional FFT with iterative refinement.
Authors: White Michael J. , Li Y. L.
Published: October 2005

A technique is presented for evaluating the field from an assembly of monopole sources embedded in a medium of homogeneous planar layers. Each layer is characterized by a sound speed, density, absorption coefficient, and thickness, and the first and last layers use an impedance condition. The main differences between this and previous implementations of the fast-field method are formulation for multiple sources, use of the two-dimensional Fourier transform, lack of any far-field restriction, and the ability for iterative refinement of the inverse transform for the pressure. Iterative refinement allows for convergence testing of the field solution without discarding previous results, making it easy to choose an optimum sampling of the spatial inverse Fourier transform. Some examples will be shown to demonstrate the ability of the new technique to solve for the near field and far field of directional sources above ground in a refracting atmosphere. Potential applications include ground impedance investigations via acoustic propagation, and prediction of the field radiated by a helicopter on its warm up pad.