Early speech motor development: The influences of cognitive and linguistic factors

Speech motor development progresses and regresses, possibly due to the interaction of cognition, language, and speech motor performance. Further knowledge regarding these relations would help inform a multifactorial, interactionist account of speech development. Oromotor behaviors of the lips and jaw were sampled and transduced using a three-dimensional motion capture system. Twenty-four infants were observed every three months, from 9 to 21 months of age. The relations of cognition and language variables to kinematic variables, such as movement speed, range of movement, and interarticulator coordination, were examined. Differences in the developmental course of three distinct oromotor behaviors (i.e., silent spontaneous movements, babbles, and words) were also investigated. Finally, the strength of the relations between the kinematic variables and cognitive and language variables was evaluated. The first study found that speed and range of movement increased with age. Only the upper lip and jaw showed change in interarticulator coordination from 9 to 21 months. The increases in these variables are likely due to maturation of the speech motor system but may also reflect the influence of cognition and language formulation. The second study found that trends for kinematic variables differed between silent spontaneous movements, babbles, and words. Spontaneous movements were generally slower than words, possibly due to the lack of auditory feedback or the need for cognition and language formulation. Speed differences between babbles and words in the upper lip may exist at some ages. These findings suggest that speech movements may reflect linguistic and cognitive processing demands and that the continuity hypothesis between babbling and words may be articulator-dependent. The final study demonstrated significant associations between kinematic variables and standardized measures of language and cognitive skills. One possible reason for these findings is that cognition is represented in movement. Another may be that increases in underlying processes affect the three domains. These studies provide fundamental knowledge about early speech motor development that will help motivate and guide future studies into the interaction of speech, language, and cognition

Increases in Cognitive and Linguistic Processing Primarily Account for Increases in Speaking Rate With Age

Age-related increases of speaking rate are not fully understood, but have been attributed to gains in biologic factors and learned skills that support speech production. This study investigated developmental changes in speaking rate and articulatory kinematics of participants aged 4 (N = 7), 7 (N = 10), 10 (N = 9), 13 (N = 7), 16 (N = 9) years, and young adults (N = 11) in speaking tasks varying in task demands. Speaking rate increased with age, with decreases in pauses and articulator displacements but not increases in articulator movement speed. Movement speed did not appear to constrain the speaking. Rather, age-related increases in speaking rate are due to gains in cognitive and linguistic processing and speech motor control

Early speech motor development: Cognitive and linguistic considerations

This longitudinal investigation examines developmental changes in orofacial movements occurring during the early stages of communication development. The goals were to identify developmental trends in early speech motor performance and to determine how these trends differ across orofacial behaviors thought to vary in cognitive and linguistic demands (i.e., silent spontaneous movements, babble, and first words). Movements of the lower lip and jaw were recorded using a three-dimensional motion capture system. Twenty-four infants were observed every 3 months, from 9 to 21 months of age. Jaw and lower lip speed, and lower lip range of movement increased with age. Silent spontaneous movements were consistently slower than words, whereas kinematic measures associated with babble did not differ from those associated with words. These findings suggest that speech movements may reflect linguistic and cognitive processing demands and that the continuity hypothesis between babbling and words may also be observed at the kinematic level

The co-emergence of cognition, language, and speech motor control in early development: A longitudinal correlation study

Although the development of spoken language is dependent on the emergence of cognitive, language, and speech motor skills, knowledge about how these domains interact during the early stages of communication development is currently limited. This exploratory investigation examines the strength of associations between longitudinal changes in articulatory kinematics and development of skills in multiple domains thought to support early communication development. Twenty-four children were investigated every 3 months between the ages of 9 and 21 months. Movements of the upper lip, lower lip, and jaw were transduced using a three-dimensional motion capture system to obtain age-related changes in movement speed and range of movement. Standardized measures of cognition and language from the Battelle Developmental Inventory, 2nd edition and the MacArthur-Bates Communicative Development Inventory were also collected. Significant associations were identified between orofacial kinematic and the standardized measures of language and cognitive skills, even when age served as covariate.These findings provide preliminary evidence of interactions between cognition, language, and speech motor skills during early communication development. Further work is needed to identify and quantify causal relations among these co-emerging skills

LIP MOVEMENT EXAGGERATIONS DURING INFANT DIRECTED SPEECH

Purpose: Although a growing body of literature has indentified the positive effects of visual speech on speech and language learning, oral movements of infant directed speech have rarely been studied. This investigation used 3-dimensional motion capture technology to describe how mothers modify their lip movements when talking to their infants. Method: Lip movements were recorded from twenty-five mothers as they spoke to their infants and other adults. Lip shapes were analyzed for differences across speaking conditions. The maximum fundamental frequency, duration, acoustic intensity, and first and second formant frequency of each vowel were also measured. Results: Lip movements were significantly larger during infant directed speech than during adult directed speech, although the exaggerations were vowel specific. All of the vowels produced during infant directed speech were characterized by an elevated vocal pitch and a slowed speaking rate when compared to vowels produced during adult directed speech. Conclusion: The pattern of lip shape exaggerations did not provide support for the hypothesis that mothers produce exemplar visual models of vowels during infant directed speech. Future work is required to determine if the observed increases in vertical lip aperture engender visual and acoustic enhancements that facilitate the early learning of speech

Accuracy of perceptual and acoustic methods for the detection of inspiratory loci in spontaneous speech

The present study investigates the accuracy of perceptually and acoustically determined inspiratory loci in spontaneous speech for the purpose of identifying breath groups. Sixteen participants were asked to talk about simple topics in daily life at a comfortable speaking rate and loudness while connected to a pneumotach and audio microphone. The locations of inspiratory loci were determined on the basis of the aerodynamic signal, which served as a reference for loci identified perceptually and acoustically. Signal detection theory was used to evaluate the accuracy of the methods. The results showed that the greatest accuracy in pause detection was achieved (1) perceptually, on the basis of agreement between at least two of three judges, and (2) acoustically, using a pause duration threshold of 300 ms. In general, the perceptually based method was more accurate than was the acoustically based method. Inconsistencies among perceptually determined, acoustically determined, and aerodynamically determined inspiratory loci for spontaneous speech should be weighed in selecting a method of breath group determination

Accuracy of perceptually based and acoustically based inspiratory loci in reading

Investigations of speech often involve the identification of inspiratory loci in continuous recordings of speech. The present study investigates the accuracy of perceptually determined and acoustically determined inspiratory loci. While wearing a circumferentially vented mask connected to a pneumotach, 16 participants read two passages. The perceptually determined and acoustically determined inspiratory loci were compared with the actual loci of inspiration, which were determined aerodynamically. The results showed that (1) agreement across all three judges was the most accurate of the approaches considered here for detecting inspiratory loci based on listening; (2) the most accurate pause duration threshold for detecting inspiratory loci was 250 msec; and (3) the perceptually based breath-group determination was more accurate than the acoustically based determination of pause duration. Inconsistencies among perceptually determined, acoustically determined, and aerodynamically determined inspiratory loci are not negligible and, therefore, need to be considered when researchers design experiments on breath groups in speech