Speech Communication

Contains reports on two research projects.U. S. Air Force Cambridge Research Laboratories under Contract F19628-69-C-0044National Institutes of Health (Grant 5 RO1 NS04332-08)M.I.T. Lincoln Laboratory Purchase Order CC-57

Intraspeaker Comparisons of Acoustic and Articulatory Variability in American English /r/ Productions

The purpose of this report is to test the hypothesis that speakers utilize an acoustic, rather than articulatory, planning space for speech production. It has been well-documented that many speakers of American English use different tongue configurations to produce /r/ in different phonetic contexts. The acoustic planning hypothesis suggests that although the /r/ configuration varies widely in different contexts, the primary acoustic cue for /r/, a dip in the F3 trajectory, will be less variable due to tradeoffs in articulatory variability, or trading relations, that help maintain a relatively constant F3 trajectory across phonetic contexts. Acoustic data and EMMA articulatory data from seven speakers producing /r/ in different phonetic contexts were analyzed. Visual inspection of the EMMA data at the point of F3 minimum revealed that each speaker appeared to use at least two of three trading relation strategies that would be expected to reduce F3 variability. Articulatory covariance measures confirmed that all seven speakers utilized a trading relation between tongue back height and tongue back horizontal position, six speakers utilized a trading relation between tongue tip height and tongue back height, and the speaker who did not use this latter strategy instead utilized a trading relation between tongue tip height and tongue back horizontal position. Estimates of F3 variability with and without the articulatory covariances indicated that F3 would be much higher for all speakers if the articulatory covariances were not utilized. These conclusions were further supported by a comparison of measured F3 variability to F3 variabilities estimated from the pellet data with and without articulatory covariances. In all subjects, the actual F3 variance was significantly lower than the F3 variance estimated without articulatory covariances, further supporting the conclusion that the articulatory trading relations were being used to reduce F3 variability. Together, these results strongly suggest that the neural control mechanisms underlying speech production make elegant use of trading relations between articulators to maintain a relatively invariant acoustic trace for /r/ across phonetic contexts

Intraspeaker Comparisons of Acoustic and Articulatory Variability in American English /r/ Productions

The purpose of this report is to test the hypothesis that speakers utilize an acoustic, rather than articulatory, planning space for speech production. It has been well-documented that many speakers of American English use different tongue configurations to produce /r/ in different phonetic contexts. The acoustic planning hypothesis suggests that although the /r/ configuration varies widely in different contexts, the primary acoustic cue for /r/, a dip in the F3 trajectory, will be less variable due to tradeoffs in articulatory variability, or trading relations, that help maintain a relatively constant F3 trajectory across phonetic contexts. Acoustic data and EMMA articulatory data from seven speakers producing /r/ in different phonetic contexts were analyzed. Visual inspection of the EMMA data at the point of F3 minimum revealed that each speaker appeared to use at least two of three trading relation strategies that would be expected to reduce F3 variability. Articulatory covariance measures confirmed that all seven speakers utilized a trading relation between tongue back height and tongue back horizontal position, six speakers utilized a trading relation between tongue tip height and tongue back height, and the speaker who did not use this latter strategy instead utilized a trading relation between tongue tip height and tongue back horizontal position. Estimates of F3 variability with and without the articulatory covariances indicated that F3 would be much higher for all speakers if the articulatory covariances were not utilized. These conclusions were further supported by a comparison of measured F3 variability to F3 variabilities estimated from the pellet data with and without articulatory covariances. In all subjects, the actual F3 variance was significantly lower than the F3 variance estimated without articulatory covariances, further supporting the conclusion that the articulatory trading relations were being used to reduce F3 variability. Together, these results strongly suggest that the neural control mechanisms underlying speech production make elegant use of trading relations between articulators to maintain a relatively invariant acoustic trace for /r/ across phonetic contexts

Speech planning as an index of speech motor control maturity

International audienceThis paper investigates speech motor control maturity in 4-year-old Canadian French children. Acoustic and ultrasound data recorded from four children, and for comparison, from four adults, are presented and analyzed. Maturity of speech motor control is assessed by measuring two characteristics: token-to-token variability of isolated vowels, as a measure of motor control accuracy, and extra-syllabic anticipatory coarticulation within V1-C-V2 sequences. In line with theories of optimal motor control, anticipatory coarticulation is assumed to be based on the use of internal models of the speech apparatus and its efficiency is considered to reflect the maturity of these representations. In agreement with former studies, token-to-token variability is larger in children than in adults. An anticipation of V2 in V1 was found in all adults but in none of the children studied so far. These results indicate that children's speech motor control is immature from two perspectives: insufficiently accurate motor control patterns for vowel production, and inability to anticipate forthcoming gestures. Both aspects are discussed and interpreted in the context of the immaturity of the internal representations of the speech motor apparatus in 4-year-old children

Speech Communication

Contains research objectives and reports on one research project.Air Force Cambridge Research Laboratories, Office of Aerospace Research, U.S. Air Force, under Contract AF19(628)-3325National Science Foundation (Grant GP-2495)National Institutes of Health (Grant NB-04332-02)National Institutes of Health (Grant MH-04737-04)National Aeronautics and Space Administration (Grant NsG-496

Speech planning in 4-year-old children versus adults: Acoustic and articulatory analyses

International audienceThis study investigates speech motor control in 4-year-old Canadian French children in comparison with adults. It focuses on measures of token-to-token variability in the production of isolated vowels and on anticipatory extra-syllabic coarticulation within V 1-C-V 2 sequences. Acoustic and ultrasound articulatory data were recorded. Acoustic data from 20 children and 10 adults have been analyzed. Thus far, ultrasound data have been analyzed from a subset of these participants: 6 children and 2 adults. In agreement with former studies, token-to-token variability was greater in children than in adults. Strong anticipation of V 2 in V 1 was found in all adults, but not in children. Most of the children showed no anticipation at all and some of them showed a small amount of anticipation along the antero-posterior dimension only, manifested in the acoustic F2 dimension. These results are interpreted as evidence for the immaturity of children's speech motor control from two perspectives: insufficiently stable motor control patterns for vowel production, and a lack of effectiveness in anticipating forthcoming gestures. In line with theories of optimal motor control, anticipatory coarticulation is assumed to be based on the use of internal models of the speech apparatus and the increasing maturation of these representations as speech develops

Speech motor control in 4-year-old children versus adults: anticipation as an index of speech motor control maturity

International audienceLearning to speak involves control of the oro-­‐facial articulators, as well as the construction of relationships between motor commands and auditory and somatosensory sensations. The main goal of this study is to further investigate the hypothesis that differences in speech production between children and adults can be explained on the basis of speech motor control maturity. With this aim, we have designed a speech production study focused on two indices: token-­‐to-­‐token variability in the production of isolated vowels, and extra-­‐syllabic anticipatory coarticulation within V1-­ C-­‐V2 sequences. Token-­‐to-­‐token variability reflects the maturation of speech motor control in terms of motor patterns for the production of a given target speech sound. In line with theories of optimal motor control, anticipatory coarticulationis assumed to be based on the use of internal models, i.e. sensorimotor representations of speech sounds, and the amplitude of anticipatory coarticulation is presumed to reflect the increasing maturation of these sensorimotor representations as speech develops. Our hypothesis is that the neural representations of the speech motor systemsof four-­‐year-­‐old children are immature, particularly in their inability to account for the appropriate variability compatible with correct perception of the target sound, leading to a lack of effectiveness in anticipating forthcoming gestures

Speech Communication

Contains reports on five research projects.C.J. LeBel FellowshipKurzweil Applied IntelligenceNational Institutes of Health (Grant 5 T32 NS07040)National Institutes of Health (Grant 5 R01 NS04332)National Science Foundation (Grant 1ST 80-17599)Systems Development FoundationU.S. Navy - Office of Naval Research (Contract N00014-82-K-0727

Articulatory Tradeoffs Reduce Acoustic Variability During American English /r/ Production

Acoustic and articulatory recordings reveal that speakers utilize systematic articulatory tradeoffs to maintain acoustic stability when producing the phoneme /r/. Distinct articulator configurations used to produce /r/ in various phonetic contexts show systematic tradeoffs between the cross-sectional areas of different vocal tract sections. Analysis of acoustic and articulatory variabilities reveals that these tradeoffs act to reduce acoustic variability, thus allowing large contextual variations in vocal tract shape; these contextual variations in turn apparently reduce the amount of articulatory movement required. These findings contrast with the widely held view that speaking involves a canonical vocal tract shape target for each phoneme.National Institute on Deafness and Other Communication Disorders (1R29-DC02852-02, 5R01-DC01925-04, 1R03-C2576-0l); National Science Foundation (IRI-9310518