bluuebunny/crossref_metadata_2025 huggingface dataset:
Stop consonant recognition and audibility in normal and hearing-loss subjects
Authors: Turner Christopher W. , Robb Michael P.
Published: October 2005

This study examined the effect of spectral cue audibility on the discrimination of CV stop consonants in normal-hearing and hearing-impaired adults. Six synthetic speech tokens, each differing only in the initial 40-ms consonant portion, were presented to subjects in randomized lists. Performance-intensity functions and relative information transmitted were calculated from the results of a six-alternative, closed-set response task, In both normal-hearing and hearing-impaired subjects, recognition performance as a function of level differed among the six consonants. The first 40 ms of each CV were analyzed via FFT using an exponential window. The resulting spectral array was passed through a sliding-filter model of the auditory system to account for the proportional bandwidth filtering properties of the ear. This allowed the spectral data to be displayed in comparison to a subject's pure-tone thresholds. Differences in the amount of predicted audible spectral speech cues resulted in observable differences in the recognition performance of individual consonants.
Learning disabled children's ability to discriminate time-compressed phonemes in sentential stimuli
Authors: Watson Marie M. , Rastatter Michael P.
Published: October 2005

This study measured the ability of a group of 8-and 12-year-old learning disabled children to discriminate phonemic contrasts in sentential stimuli presented at a 50% time compressed rate. These responses were compared statistically to similar data gathered from a group of 6-, 8-, and 10-year-old normal children and adults. Results were interpreted as suggesting that the learning disabled children exhibit auditory processing capacities reminiscent of an earlier level of operation, but also manifest marked differences in their feature and frequency processing abilities when compared to normally achieving children.
History of text-to-speech conversion for English
Authors: Klatt Dennis
Published: October 2005

Text-to-speech conversion is now a practical technology with a history of research and development spanning at least 50 years. With the hope that valuable insight and perspective can be gained by examination of the evolution of a science, a literature search to trace the history of text-to-phoneme and phoneme-to-speech algorithms has begun. The paper will present a preliminary status report of this attempt to identify important milestones in the evolution of systems capable of generating intelligible English sentences from text, and trace the scientific lineage of selected commercial systems. A second potential benefit of relating technology to prior basic science is in identifying missing pieces in the puzzle as to why synthetic output is lacking in naturalness. Some conjectures concerning possible causes will be followed by suggestions for future research relevant to this domain. [Work supported in part by an NIH grant.]
Preference judgments comparing different synthetic voices
Authors: Logan John S. , Pisoni David B.
Published: October 2005

Speech from three text-to-speech systems was compared on the basis of listeners' preferences. Subjects heard a sentence produced by one system followed by the same sentence generated by another system. The task was to indicate which of the two voices they preferred and then furnish a confidence rating for the decision. Each subject was presented with 40 pairs of sentences. Ten subjects participated in each of the three pairwise comparison conditions: (1) DECtalk compared with MITalk, (2) DECtalk compared with the Prose-2000, and (3) MITalk compared with the Prose-2000. The overall relationship among preference, response time required for this decision, and the confidence rating was examined. Results indicated a direct relation between preference and intelligibility whereas the remaining measures did not appear to be systematically related to preference. These subjective judgments will be discussed in terms of the relationships among preference, naturalness, and intelligibility in the perceptual evaluation of natural and synthetic speech. [Work supported by AFOSR and NIH.]
Evaluation of a synthesized Spanish accent
Authors: Rekart Deborah M. , Daniloff Raymond G. , Hoffman Paul R. , Miller C. J.
Published: October 2005

English speakers' perception of a synthetic sentence with a moderate Spanish accent was reported on previously [J. Acoust. Soc. Am. Suppl. 1 77, S9 (1985)]. It was found that an increased number of cues caused significantly higher ratings, and formant frequency perturbation of full vowels was the strongest cue signaling accentedness. The present research investigated perception of newly synthesized strong and moderate accents, manipulating F0, VOT of syllable-initial voiceless stops, duration of sentence-medial stressed vowels, and formant frequency for full and reduced vowels. For each condition, the accented sentences were paired with the standard sentence in four randomizations. Forty-two English speakers rated how different each accented sentence was from the standard sentence and indicated confidence in their judgments. It was found that the synthetic English sentence was reliably rated for cue modifications indicative of a moderate Spanish accent; an increase in number of cues resulted in perception of increased accentedness and higher confidence ratings for both accents; F0 and formant frequency perturbation in full vowels were the most prominent cues signaling moderate Spanish accent, and their presence resulted in higher confidence ratings.
An investigation of mixed-source excitation models for linear predictive vocoders
Authors: Effer Elizabeth A. , Zahorian Stephen A.
Published: October 2005

Two methods were investigated for modeling the excitation for linear predictive vocoders as a mixture of pulses (periodic component) and noise (nonperiodic component). In one method, linear filters were used to separate the periodic and nonperiodic components of the residual signal. In another method, the two components were separated by locating the areas of peak energy in the residual and labeling the portion of the residual within each pitch period peak as the periodic component and the remainder of the signal as the nonperiodic component. Thus, in the first method, a frequency domain separation of the periodic and nonperiodic component was assumed whereas, in the second method, a time-domain separation of the two components was assumed. The time-domain method appeared to be more feasible. Speech was synthesized using a number of parameters to represent the two components of the excitation. Although some improvements in speech quality could be obtained by using very detailed representations of the pulses, less-detailed representations resulted in poorer quality speech than that obtained using a standard impulse excitation.
On the struggle of underlying vowels for a voice in surface phonetic structure—Evidence from Serbo-Croation
Authors: Ridjanovic Midhat
Published: October 2005

An outstanding feature of the colloquial speech of Sarajevo in relation to standard Serbo-Croatian is the deletion of the high vowels [i] and [u] in post-accentual syllables. This gives rise to frequent “homonymy” of forms clearly distinguished in the standard language. The present work was undertaken to test the hypothesis that this homonymy is not perfect, i.e., that there could be phonetic remnants of the deleted vowels in adjacent segments. An experiment is being conducted in which (a) tape recordings of purportedly homonymous triplets of forms, two with deleted [i] and [u], respectively, and one involving no deletion, are presented to speakers of both the Sarajevo and the standard dialects of Serbo-Croatian for perceptual judgments, and (b) spectrographic analysis is carried out to discover possible mutual acoustic differences. Preliminary results have suggested that, in a majority of cases, the forms are preceived as if they contained the appropriate vowel [i] or [u] and that residual features of the deleted vowel may appear in the spectrograms of both contiguous segments.
Distinctive length in initial consonants: Pattani Malay
Authors: Abramson Arthur S.
Published: October 2005

The relative duration of the closure or constriction is the most salient physical manifestation of phonemically distinctive consonant length. The contrast is rare in the word-initial, and thus potentially utterance-initial position. In this context, perception would seem to depend upon the audibility of closure excitation. This is plausible for nasals, laterals, and fricatives. The closures of voiced stops, however, may have only low-amplitude excitation, while voiceless stops have none. Pattani Malay, a language of southern Thailand, was investigated to learn how robust the feature is in production and perception. Acoustic measurements of closure durations showed a reliable difference between the “short” and “long” consonants. Listening tests yielded good differentiation of the two length classes for isolated words, with a lesser effect for voiceless stops. Experiments with incrementally lengthened short closures and shortened long closures confirmed the sufficiency of duration as a cue. For the voiceless stops, these experiments could be run only for intervocalic position. Further work will seek other acoustic consequences of duration that might serve as cues. [Work supported by NICHD.]
A new way to compute underwater acoustic bottom loss: Concept and application to borehole data
Authors: Fisher Craig A. , Duennebier Frederick K.
Published: October 2005

Bottom reflection loss cannot be computed with traditional methods using data from a borehole receiver. A grazing angle-dependent loss, unique to the borehole case, is incurred as a ray passes through the overlying sediments and basalts. To compute bottom loss from these data this grazing angle-dependent loss must be removed. Another angle-dependent loss, image interference, can also be present when the source is near an interface. We gave a bottom loss computation method which implicitly removes angle-dependent losses. In addition, our method is “self-calibrating” in both grazing angle and frequency. This technique uses multiple bottom-interacting rays with the same grazing angle to obtain redundant bottom loss estimates. The algorithm is applied to a data set recorded with a borehole receiver in the deep ocean at DSDP site 581C. For grazing angles from 20 to 60 deg and frequencies from 9 to 40 Hz we computed bottom reflection loss estimates of 1 to 12 dB, ± 2 dB. [Work supported by ONR.]
Modeling underwater acoustic communications at moderate ranges
Authors: Thompson J. K. , Naghshineh K. , Gates K. B.
Published: October 2005

This paper describes the analytical development and performance of a computer model of underwater sound transmission. This model is intended to simulate underwater acoustic communications over short to moderate ranges between subsurface transducers and buoys. Because of the high frequencies used in communication, the ray tracing method is employed in this simulation. The computations employed in this model are thoroughly described and compared to previous research. New developments of this study include a finite receiver dimension to account for the spreading of the acoustic energy in rays and an “eigenray” routine to minimize computation time and expense. Comparisons of calculations by this model and measured data were performed to determine the model's accuracy. The maximum predictive error of 5 dB would be acceptable in most communication applications. In no instance were extreme variations between the measured and calculated results encountered. [Work supported by NOAA Data Buoy Center of NSTL Station, Mississippi.]
Shape of the wavefront which produces a transverse cusp diffraction catastrophe
Authors: Marston Philip L.
Published: October 2005

Diffraction patterns characteristic of a transverse cusp are known to be observable in light scattered from drops [P. L. Marston, Opt. Lett. 10, 588–590 (1985)] or reflected from curved surfaces. It is to be expected that high-frequency sound reflected from curved surfaces or refracted by inhomogeneities may also produce transverse cusps but to facilitate their description one must know the shape of the outgoing wave which propagates to produce such a cusp. A wave whose amplitude in the xy plane is exp[ik(a1x2 + a2y2x + a3y2 − ct)] is considered and the two-dimensional diffraction integral which results from the Fresnel approximation of the Green's function is calculated. This diffraction integral reduces to one proportional to the Pearcey function P(X, Y) or to P* (X, Y) depending on the sign of a1 + (2z)−1, where is the distance from the xy plane. The real parameters X,Y in the one-dimensional integral P depend on the aj, z, k, and the transverse coordinates in the observation plane. This transformation locates the cusp where geometric optics fails. The shape of the wave differs from that which produces a longitudinal cusp present in certain convergence zones. [Work supported by ONR.]
Improved paraxial methods for modeling underwater acoustic propagation
Authors: Bordley Thomas E.
Published: October 2005

Current paraxial techniques for modeling wave propagation in the ocean perform poorly when bottom interaction is important due to their inability to handle wide-angle propagation. Such methods solve a simplified form of the acoustic wave equation, obtained by splitting the field into transmitted and reflected components, and then neglecting the reflected field. The concern of this work is to develop paraxial methods less restricted in angle, yet retaining the numerical stability and efficiency which have made this class of solutions so popular. The approach taken is to seek a split, in some sense, most consistent with the assumption that the modeled field closely approximates the “true” field. The measure of consistency adopted is the closeness of the split to the split implied by the field under the assumption that the parabolic and elliptic equations agree. An iterative algorithm is developed realizing this scheme which at each step, uses the current estimate of the field to generate a more consistent split for the next step. The new split is that which necessarily existed if the current estimate of the field were exact. The effectiveness of this approach is examined in the context of modeling sound propagation in the Arctic marginal ice zone.
Notes on wide angle PE
Authors: Frazer L. Neil , Sen Mrinal K.
Published: October 2005

In many applications the parabolic equation method would be ideal were it not for the limitation to narrow angles. Recently, Fishman and McCoy [J. Math. Phys. 25, 285–296 (1984)] used the theory of pseudo-differential operators to derive an integral equation for H, the square root of the operator B = ω2/c2(z) + ρ(z)∂z[ρ−1(z)∂z], thereby obtaining an exact, arbitrary-angle PE theory. Numerical construction of the operator H = B remains an area of great interest because the integral equation for H is not easily solved. We show that the operator H can be numerically constructed to any desired accuracy by well-known methods of computational linear algebra. The key to this construction is that, whenever the sound-speed profile is real, the operator B is self-adjoint with respect to the inner product 〈,〉 where 〈φ,ψ〉 = ∫ dz ρ−1(z) φ̄(z)ψ(z). This means that the matrix of B can be diagonalized, hence, H =B and exp(iΔxH) are straighforward to compute. [Work supported by ONR.]
Parabolic decomposition of the separable Helmholtz equation
Authors: Wood David H.
Published: October 2005

The solution of the separable Helmholtz equation is represented as the convolution of solutions of two related (formally) parabolic partial differential equations. Separable means that the square of the index of refraction is a function of depth plus a function of range and that the depth of the ocean is assumed to be constant. This representation decomposes the separable Helmholtz equation into two parabolic partial differential equations. One equation is the usual Fock-Tappert parabolic equation for sound propagation. The solutions of the second parabolic equation may be regarded as candidate kernels of special integral transformations, or transmutations. All of these equations have many solutions, of course, so we present initial and/or boundary conditions that will determine solutions of the parabolic equations so that their convolution will give the Green's function for the Helmholtz equation. Examples of such transmutation representations will be presented.
Sound transmission loss in a rectangular attenuator symmetrically lined with continuously variable flow resistance
Authors: Shenoda F. B. , Haroun R. N. , Selim Hany
Published: October 2005

The sound attenuation in a free-path rectangular duct of constant cross-sectional area was theoretically studied for the case of a symmetrically decreasing wall resistance at its both ends. The change of the wall conductance from either side was thereby taken to be parabolic. In addition to the high transmission loss it possesses, this attenuator was found to be wideband and to have small reflection coefficients at both ends, if it is inserted between two similar hard ducts. The solution of the obtained Bessel differential equation consists of a combination of modified Hankel functions of the order 1/3. The attenuator characteristic at a certain frequency was found to depend only on both the duct length and an attenuator characteristic area (A) defined as A = S/g, where S is the actual attenuator cross-sectional area and g is a normalized wall conductance at a distance of 1 cm from attenuator ends. Compared to the case of the homogeneous lined attenuator, the insertion of the proposed attenuator between two hard ducts was found to give a much smaller reflection coefficient at comparable values of sound transmission loss. This is due to its good matching characteristics at both ends. As an example of calculations, a duct of 1-m length having a characteristic area of 500 cm2 was found to have an average transmission loss of about 17 dB for the frequency range up to 600 Hz. Meanwhile, the reflection coefficient was found to decrease with frequency and to have a value less than 0.1 for frequencies above 350 Hz. Experimental results were found to be in fair agreement with the theoretical results. It is worth mentioning that parabolic change of the wall conductance can be realized by means of a homogeneous sound absorbing flow resistance together with a slit which changes parabolically along the length of the attenuator. By the experimental implementation of this slit, a variable perforation area having the same dependence on length and perforation ratio of more than 35% was used. Due to the small reflection coefficient it possesses at both ends, this attenuator can be used as an exhaust silencer.
The use of spreadsheet programs for noise control problems
Authors: Saha Pranab
Published: October 2005

Spreadsheet programs, once used as a financial/business tool, can be effectively used for solving acoustics and noise control problems using a personal computer. The spreadsheet allows one to write a pseudoprogram in terms of algebraic expressions which follows algorithms similar to our thinking process. The spreadsheet is essentially a two-dimensional matrix where entries can be made both in rows and columns. The entries, called cells, contain different types of information, such as numbers and formulas. Numbers are like expressions with fixed values. Formulas are algebraic expressions where references can be made to other parts (cells) of the program. These expressions are computed in a similar fashion as is done in a calculator but at a much faster speed. Also, the spreadsheet computer program has plenty of flexibility and versatility in many areas compared to a conventional digital computer program. One of these is the automatic updating of all results (algebraic expressions) that are affected due to the change of a value in the spreadsheet. This paper discusses the VISI-CALC® computer program spreadsheet. A worker noise exposure prediction problem is demonstrated using the VISI-CALC® program with a Hewlett-Packard desktop computer.
Discovery of the world of sound
Authors: Roller Stanley H.
Published: October 2005

This is an audiovisual demonstration of a wide range of acoustical phenomena originally prepared to instruct architects on the physical phenomena important to their work. Among the topics presented are transmission loss, binaural hearing, the precedence effect, etc. The presentation is approximately one hour in length and will be shown at 9:00, 1:00, 3:00, and 5:00.
The external ear sound pressure level transformation in infants
Authors: Bernstein Richard S. , Kruger Barbara
Published: October 2005

Some preliminary findings obtained in a study of the acoustic characteristics of the external ears of infants are reported. A technique was developed for positioning the inlet of a probe-tube microphone in the lateral-half of the ear canals of sleeping infants. A diffuse sound field (spectral density approximately 42 dB SPL) was introduced and the microphone output recorded. Free-field-to-ear canal sound pressure level transformations were determined for infants ranging in age from a few days old to 36 months. Representative transformations are presented, and these vary systematically with the age of the child. The resonance frequency of the external ear is high in newborns and declines exponentially with age. The asymptotic value (approximately 2700 Hz) appears to be reached during the second year of life. [Work supported by NIH-NINCDS.]
Design of prostheses for the middle ear
Authors: Nassef A. M. , Finch R. D. , Mistree F. , Gray L.
Published: October 2005

The middle ear has been modeled with an assembly of mechanical components, and the values of the parameters in that model were determined using an optimization technique [J. Acoust. Soc. Am. Suppl. 1 77, S94 (1984)]. Certain diseases of the middle ear are treated by replacement of the three ossicles which transmit sound from the outer ear to the inner ear. It is normal to replace the three ossicles by a prosthesis consisting of a simple rod. Such devices do not restore hearing fully, and the same device is not suitable in all cases. The overall aim of this work is to develop the capability to select the best configuration to restore acoustical response, to choose the best material to be used in manufacturing such a prosthesis, and to determine the dimensions of the device. To reach this aim, the following are the steps to be taken: (1) Reproduce the acoustical transfer function of a normal middle ear as accurately as possible; and (2) meet surgical constraints such as ease of implantation and resistance to disease. In this paper, we discuss some designs, set up the mathematical formulation to determine the principal dimensions of these different designs, and present some results which include a comparison of the characteristics of new designs and those currently used.
Extraction of the neural count function from the Weber fraction
Authors: Hellman William S. , Hellman Rhona P.
Published: October 2005

It is shown that the dependence of the Weber fraction, ΔI/I, on I determines the form of the neural firing rate function N(I) provided that the relation between ΔN and N is given. Here, ΔN is the change in average firing rate resulting from an intensity jnd. The firing rate function consistent with Weber's law is predicted when ΔN ∼ N1/2. Assuming that loudness is proportional to the neural firing rate, loudness equations are constructed for two stimuli where Weber's law is obeyed and empirical loudness functions are available. These stimuli are (1) a 100-Hz tone partially masked by an adjacent high-pass noise and (2) broadband noise. Close agreement between the derived and measured loudness functions is obtained. The procedure also predicts a power law for loudness, with a generalization, when the near miss to Weber's law is represented by a power function. [Partially supported by the Rehabilitation Research and Development Service of the VA.]
Effect of sloping high-frequency cochlear losses on loudness functions at lower frequencies
Authors: Hellman Rhona , Meiselman Carol
Published: October 2005

The relation between loudness at low and middle frequencies and auditory thresholds at high frequencies was determined in a hearing-impaired population with sloping high-frequency cochlear losses. Nine people, all with steep symmetrical bilateral losses, participated in the study. Loudness was measured at two frequencies in the normal-hearing region by magnitude estimation and production. Despite a marked increase in thresholds at frequencies just above the upper test frequency, both the dynamic range measured for loudness and the tone's rate of loudness growth were essentially the same at the two test frequencies. Moreover, the loudness functions were the same as the monaural loudness function measured at 1000 Hz in normal hearing. Consistent with the findings of other studies, the results indicate that the magnitude of loudness does not depend on the high-frequency excitation pattern evoked by the tone in the ear. [Supported by the Rehabilitation Research and Development Service of the VA.]
Acoustic energy transfer and intensity vortices
Authors: Mann J. Adin , Tichy Jiri
Published: October 2005

Concepts of energy transfer in an acoustic field will be discussed using the vectorial, transient, and steady-state properties of acoustic intensity. Emphasized is the region of an active intensity vortex. Pascal's decomposition of the active intensity into a part with zero and nonzero curl will also be included, but with different conclusions. Calculated results of the build up of a vortex and steady-state fields and data from an automated measuring system will be used in the discussion.
Stress pattern differentiation of form class in English
Authors: Sereno Joan A.
Published: October 2005

The present experiment explores the regular stress pattern that differentiates nouns and verbs in English. In some English words, a shift in stress from the first to the second syllable produces a change in form class from noun to verb (e.g., SURvey, noun; surVEY,verb). However, preliminary results suggest that this stress pattern is not solely restricted to this rather limited set of words. An analysis of the Brown Corpus [Francis and Kučera, Frequency Analysis of English Usage (Houghton Mifflin, Boston, 1982)] revealed that the vast majority (92%) of bisyllabic words used only as nouns in English have first syllable stress (e.g., “student,” “country”) whereas the great majority (85%) of bisyllabic verbs have second syllable stress (e.g., “begin,” “receive”). In the present experiment, “ambiguous” bysyllabic words (i.e., words that do not change their stress placement with a change in form class) were examined. In these words (e.g., “answer,” “design”), acoustic measurements (duration, amplitude, fundamental frequency, and second formant frequency levels) were taken. Some stress-related acoustic differences were found between the ambiguous bisyllabic words read as nouns and those same words read as verbs. The results will be discussed in terms of their significance for lexical organization.
Speech produced under high sustained acceleration: Some preliminary observations
Authors: Bond Z. S. , Moore Thomas J. , Anderson Timothy R.
Published: October 2005

The purpose of this study was to obtain preliminary data concerning the acoustic-phonetic structure of speech produced under high sustained acceleration. Acoustical measurements were made of a set of Air Force vocabular words as spoken by two subjects at 1 g and 6 g's. There were differences in both the durational and spectral characteristics of speech, though not always consistently for the two speakers. At 6 g's, vowel formants tended to centralize, and fundamental frequency in stressed syllables increased for both speakers. For one speaker, word durations increased consistently under acceleration while for the other speaker, the durational differences were inconsistent. Duration differences were primarily a function of changes in vowel duration. [Sponsored in part by the Air Force Office of Scientific Research/AFSC, United States Air Force, under Contract F49620-85-C-0013.]
Formant estimation of high fundamental frequency speech
Authors: Bickley Corine
Published: October 2005

Formant measurement procedures often rely on there being a low fundamental frequency. An early study [B. Lindblom, International Congress of Phonetic Sciences, 4th, Helsingfors, 1961, 189–202 (1962)] found that the mean error in formant estimation ranged from about 40 Hz to a frequency of one-fourth the fundamental. This study compares signal processing techniques for the estimation of formant frequencies and bandwidths of synthesized and natural speech characterized by a high fundamental frequency. Utterances were synthesized [D. H. Klatt, J. Acoust. Soc. Am. 67, 971–995 (1980)] using young children's utterances as models. The spectral and durational characteristics were matched closely by manipulating the synthesizer parameters. Spectrograms, discrete Fourier transforms, linear prediction envelopes, and auditory pseudospectrograms were computed for both the synthesized and natural utterances. The accuracy of formant estimation was judged by comparing the values determined by each of these methods to the known frequencies and bandwidths of the synthesized speech. Implications for formant estimation of natural speech will be discussed. [Work supported in part by a Whitaker Health Sciences Fellowship.]
The differential performance of older speakers in initiating and terminating phonation as a function of health status
Authors: Trudeau Michael D. , Mosca Dawn , Oyer Herbert J.
Published: October 2005

The purpose of this study was to determine the utility of vowel initiation tune (VIT) and vowel termination time (VTT) in discrimination between healthy and unhealthy elderly speakers. Sixty-three adults age 60–94 years sustained /a, e, i, o, u/ for at least 1 s. From audio recordings of these productions means and standard deviations of VIT and VTT were derived. A MANOVA based on speaker gender (36 females, 27 males) and speaker health status (42 unhealthy, 21 healthy) yielded a significant difference in performance in VIT as a function of health status but for gender on the interaction. A subsequent linear discriminant analysis using mean VIT correctly classified subjects in the unhealthy group with 33.3% accuracy (3 times greater than chance levels) and subjects in the healthy group with 95.2% accuracy. These results support the hypothesis that the degree of coordination between respiration and phonation reflects the health status of the older adult.
The effects of orthognathic osteotomy on formant structure
Authors: George Jeanne , Trudeau Michael D.
Published: October 2005

The objectives of this study were to determine the effect of orthognathic surgery on vowel production and the persistence of this effect beyond the immediate post-surgery period. Seven females provided cephalometric radiographs pre- and post-surgery and speech samples of /hd/ syllables for acoustical analysis 1 to 2 days prior to surgery, immediately following removal of intermaxillary fixation, and again 3 to 4 weeks later. Spectrographic analysis of the vowels' first two formants revealed little change between any of the three intervals. The only exception was a significant inverse relationship between vertical alteration of the oral cavity and change in F2 for front vowels. This relationship appeared only in comparing formant change between the presurgery sample and the final sample obtained 3 to 4 weeks after intermaxillary fixation had been removed (r = −0.865, d.f. = 5).
Three-dimensional model for piezoelectric ceramic mode vibration determination
Authors: Brissaud M. , Eyraud L. , Kleimann H.
Published: October 2005

The demand for imaging properties of ever increasing quality in ultrasonic echography requires an analytical tool able to give easy predictions of the transducers' performances. Though algorithms based on the finite element method are able to solve the steady-state problem [O. C. Zienkiewicz, The Finite Element Method (McGraw-Hill, New York 1977)], the analytical methods are often preferred because the numerical approaches do not give sufficient insight into the physical parameters which should be kept under control in the design of piezoelectric transducers. The aim of this paper is the analysis of the vibration of rectangular or beam-shape ceramics transducers used in acoustical imaging. Coupling between thickness and lateral modes is taken into account. The general electrical impedance of the transducer is Z = 1jC0ω [1 − h31c33D − h33c13D(c11D + c12D) c33D − 2c13D × h31β33S (1cos(ωa1/2v) + 1cos(ωa2/2v)) − kt2 1 − 2h31c13D/h33(c11D + c12D)1 − 2c13D2/(c11D c12D) c33D tan(ωa3/2v3ωa3/2v3], where ɑi,cijD,hij,C0 are the geometrical dimensions, the stiffness and piezoelectric constants, and the capacitance of the ceramic, respectively. When h31 and c13D vanish, the electrical impedance formula becomes that given by W. P. Mason [Physical Acoustics (Academic, New York, 1964), Vol. 1, part A].
The effect of masker bandwidth on signal detectability
Authors: Bernstein Richard S. , Raab David H.
Published: October 2005

The effect of masker bandwidth on the detectability of narrow- and wideband signals was investigated. The signals were pure tones and noise bands. The noise bands varied from 50–792 Hz, center frequency being 1500 Hz. Stimuli were computer generated and the noise bands had nearly rectangular spectra. Log-log plots of threshold as a function of masker bandwidth (Fletcher plots) were found to be well fitted by two line segments. An iterative least-squares procedure was employed to determine slopes and intercepts of the line segments. These parameters were found to depend on the bandwidth of the signal. An energy detection model [Green, J. Acoust. Soc. Am. 32, 121–131 (1960)] was modified by the addition of internal variability that is bandwidth-dependent. This modified energy-detection model was able to predict the results obtained with narrow bandwidth signals. The relative magnitude of internal variability was estimated and the ratio of internal-to-external variability agreed with estimates presented by Raab and Goldberg [J. Acoust. Soc. Am. 57, 437–447 (1975)]. In contrast, the results obtained with wideband signals were not predicted by the simple model. They may reflect the operation of a mechanism for the enhancement of spectral contours.
Evoked response “forward-masking” functions in hearing-impaired chinchillas
Authors: Arehole Shalini , Salvi Richard J. , Saunders Samuel S. , Henderson Donald
Published: October 2005

Previous research in psychophysics has shown that the time course of recovery from forward masking is prolonged in listeners with sensorineural hearing loss (Nelson and Turner, 1980). In order to evaluate the physiological basis for the change in the time course of forward masking, evoked response recordings were obtained from the inferior colliculus of the chinchilla both before and after noise induced hearing loss. Evoked response “forward-masking” functions were obtained by measuring the masker level required to produce a 50% reduction in the response to a probe tone (re: probe response alone) which followed the masker at various time intervals (2 to 100 ms). The time course of “forward masking” was estimated by fitting a time constant to the data. Animals were exposed to a pure tone that produced either 30–50 dB of asymptotic threshold shift or 25–30 dB of permanent threshold shift. The time constants fit to the “forward-masking” function were found to be prolonged in the region of hearing loss. In general there was a strong correlation between the time constant of recovery from “forward masking” and hearing loss. The implications of these results will be discussed. [Work supported by NIH 5-R01-NS16761-06 and NIOSH 1-R01-OH00364.]
Acoustic radiation force on a particle in a temperature gradient
Authors: Collas P. , Barmatz M.
Published: October 2005

An expression for the acoustic radiation force on a small spherical particle of radius R in a standing wave field is derived. The particle is inside a long tube chamber with a temperature gradient along the axis of symmetry. Assuming R < λ, and neglecting convection, acoustic streaming, heat conduction, and viscosity effects, an expression for the force that consists of a “local” version of Gor'kov's result [L. P. Gor'kov, Sov. Phys. Dokl. 6, 773 (1962)] as well as correction terms of order βλ, where β = T′/T, is obtained. Also the effect of various temperature gradients on the acoustic positioning (levitation) properties of the system is investigated numerically. The results of this analysis will be compared to the uniform temperature case. [Work supported by NASA.]
Acoustic radiation force in a dual-temperature resonant chamber
Authors: Robey J. , Trinh E.
Published: October 2005

The acoustic radiation force was measured for a dual-temperature resonant chamber. This rectangular chamber has its long dimension approximately 8.5 times the square cross-sectional dimension and the opposite ends are at widely different temperatures. Force profiles were obtained for two hot-end temperatures of 500 °C and 750 °C, while the cool end remained at approximately room temperature. The lateral force was measured as a function of the long dimension of the chamber along the temperature gradient, and as a function of the drive voltage. The highest force per unit mass measured at 500 °C was 103.8 dyn/g for a frequency of 4450 Hz, and at 750 °C the highest force was 82.8 dyn/g for a frequency of 5500 Hz. Qualitatively, the measured force profiles correspond well with the theoretical curves; however, correlation of absolute magnitude is yet to be determined. [Work supported by NASA.]
A finite element analysis program for reverberant spaces
Authors: Sabo Larry , Ochs John B. , Delph Terry
Published: October 2005

A finite element analysis program has been developed to analyze the spatial distribution of pressure in irregularly shaped reverberent enclosures driven by a point source. The program uses a matrix form of the modified Helmholtz equation with a driving source term where soft wall boundary conditions are introduced with Galerkin's method to yield a complex symmetric matrix. The results compare well with the closed form solution for a point source and homogeneous absorption material on all walls over the low range of frequencies and for several absorption coefficients. However, at higher frequencies corresponding to higher eigenvalues, the low mesh density introduces error that corresponds to an increase in stiffness. Irregular shapes have also been studied. Effective use of the program for spatial distribution and frequency response analysis for forced vibration requires appropriate mesh density, adequate computer resources, and computer graphics to interpret the results. [Work sponsored by Knoll International.]
Acoustic shape optimization using the finite element method
Authors: Bernhard Robert J. , Milner Joseph R.
Published: October 2005

Information to predict the sensitivity of acoustical response to geometric shape variations can be calculated using the acoustic finite element formulation [R. J. Bernhard, J. Sound Vib. 98, 55–65 (1985)]. Such sensitivity information can be utilized to indicate to a designer the change of each geometric design variable necessary to achieve a better solution. The sensitivity information also indicates which design variables have minimal effect on the solution and how close the current solution is to an optimal condition. When the condition of the design can be quantified with a performance equation, numerical optimization procedures can be used to systematically find the optimal solution. Sensitivity information also permits the use of efficient gradient optimization algorithms. This paper will illustrate the incorporation of the acoustic finite element shape sensitivity information into a gradient optimization procedure. The design procedures for reactive mufflers will be illustrated. When modal techniques are appropriate for the solution of a particular problem, the shape sensitivity information may also be utilized to find modal sensitivity information.
Application of damping elements to the modeling of underwater radiating structures
Authors: Bossut Régis , Decarpigny Jean-Noël , Tocquet Bernard , Boucher Didier
Published: October 2005

In the finite element method, the damping or radiating elements are often used to limit the extension of the modeling of the propagation media surrounding the radiating structure, and thus to reduce the number of fluid elements. The radiation condition is generally related to the spherical wave acoustic impedance. Recently, an improved radiating element has been developed [R. Bossut and J. N. Decarpigny, J. Acoust. Soc. Am. Suppl. 1 74, S23 (1983)], based on Bayliss et al.'s results [ICASE Rep. No. 80-1, USRA (1980)], which takes account of the dipolar contribution of the wave impedance. The work described here demonstrates that with this damping element, the F.E.M. computed pressure map, on the radiating structure and in the nearfield, is given with low error, even if the radiating surface stands deeply inside the farfield limit. Thus, a finite element analysis can provide, even with a reduced mesh, an accurate starting point for the computation of the farfield, with the help of a Helmholtz integral or an extrapolation method. Several examples are discussed.
On attributing a “phonetic level” to infants
Authors: Kuhl Patricia K.
Published: October 2005

There are two distinct characterizations of young infants' linguistic ability. One account argues that infants are born with a specialized system that subserves the processing of linguistic information and that formal linguistic categories are pre-specified. This account holds that there is an “innate phonetics.” The alternative account argues that young infants do not begin with formal linguistic categories. This account holds that a “phonetic level” develops at some point, guided by the infant's more general auditory abilities and cognitive strategies. An examination of the data and the arguments over the past 15 years shows that the pendulum has swung between these two characterizations. The first experiments on infants, showing categorical perception (CP) in 1-month-olds, led to a positive attribution of a “phonetic level” to infants. Later data replicating these effects in nonhuman animals removed the need to impute specialized linguistic mechanisms to infants in order to account for the CP effect. Now we have new data on infants reflecting an even more sophisticated perceptual organization of speech. These examples involve infants' abilities to categorize speech, to organize speech categories around a central “prototypical” stimulus, and to recognize cross-modal correspondences between speech information presented auditorially and visually. These data, along with our new results on animals, will be used to reconsider the initial issue about whether or not we should attribute a “phonetic level” to infants. [Work supported by NIH and NSF.]
The development of cross-language speech perception
Authors: Werker Janet F.
Published: October 2005

The present research was designed to determine whether infant speech perception capabilities can be explained by acoustic categorization, or whether phonetic (or at least phonetically relevant) categories must be inferred. A 16-step, synthetic place-of-articulation continuum was used. Preliminary testing showed that adult English speakers divide this continuum into two categories, /ba/-/da/, and adult Hindi speakers divide it into three categories, /ba/-/da/-/da/. Infants aged 6–8 and 11–13 months were compared to Hindi- and English-speaking adults on their ability to discriminate multiple exemplars from either side of one of three boundary locations: “Both”—the English and Hindi front/mid-boundary; “Hindi only”—the Hindi dental/retroflex boundary; and “Neither”—an arbitrary point in the “da” end of the continuum that no language uses to differentiate meaning. Results showed that young infants and Hindi adults could categorize stimuli at the “Both” and “Hindi-only” locations but not at the “Neither,” but that older infants and English adults could only use the “Both” boundary. These results show the phonetic relevance of initial infant speech perception capabilities, and further demonstrate that these capabilities are reorganized during the first year of life into language-specific phonemic categories. [Work supported by NSERC.]
Discrimination differences for children and adults due to changes in a priori ratio between same and different trials
Authors: Sussman Joan E.
Published: October 2005

In a previous study [Sussman and Carney, J. Acoust. Soc. Am. Suppl. 1 75, S45 (1984)] it was found that normal-language children demonstrated a developmental increase in sensitivity to fine acoustic cue differences of long-transition synthetic CV stimuli but not for short-transition stimuli in a discrimination task. In addition, criteria used by children differed significantly from those used by adults. An a priori ratio between same and different trials of 0.25:0.75 was used. The present discrimination study used the same short-transition synthetic stimuli which varied along a seven-step continuum that corresponded to a place of articulation dimension. Discrimination sets with proportions of same to different trials of: 0.50:0.50, 0.33:0.67, and 0.67:0.33 were administered to 30 children and 10 adults in individual experimental sessions. Results showed that sensitivity did change with a priori condition while criteria used by adults were more strict than those of children. Patterns of criteria according to a priori condition will be discussed. [Work supported by ASHF.]
Variability of timing control: Maturational or statistical?
Authors: Crystal Thomas H. , House Arthur S.
Published: October 2005

Segmental durations have been studied extensively in the context of motor control and skilled action. Rather consistently it has been found that the mean durations of sounds, and associated standard deviations, produced by younger children are larger than those produced by older children and adults. This putative lengthening and increased dispersion is of interest since, if reduction of duration with age is a consequence of neuromuscular maturation, such durational measures may serve to characterize developmental progress in motor control. Kent and Forner [J. Phonet. 8, 157–168 (1980)] have pointed out, however, that “heightened variability…may really be evidence…that slow speakers are more variable…than fast speakers” independently of maturational considerations. We have examined measurements made on readings of two scripts by three fast and three slow talkers drawn from larger groups. In this corpus, as well as an earlier one [J. Acoust. Soc. Am. 72, 705–716 (1982)] the distributions of speech sounds are skewed. This suggests that the standard deviation of distributions of durational measurements does not provide an independent indication of variability that allows inferences about motor control or maturation. Sample distributions and correlations of mean values and SD's will be shown.