Purpose: Current approaches to speech production aim to explain adult behavior and so make assumptions that, when taken to their logical conclusion, fail to adequately account for development. This failure is problematic if adult behavior can be understood to emerge from the developmental process. This problem motivates the proposal of a developmentally sensitive theory of speech production. The working hypothesis, which structures the theory, is that feedforward representations and processes mature earlier than central feedback control processes in speech production.Method: Theoretical assumptions that underpin the 2 major approaches to adult speech production are reviewed. Strengths and weaknesses are evaluated with respect to developmental patterns. A developmental approach is then pursued. The strengths of existing theories are borrowed, and the ideas are resynthesized under the working hypothesis. The speech production process is then reimagined in developmental stages, with each stage building on the previous one.Conclusion: The resulting theory proposes that speech production relies on conceptually linked representations that are information-reduced holistic perceptual and motoric forms, constituting the phonological aspect of a system that is acquired with the lexicon. These forms are referred to as exemplars and schemas, respectively. When a particular exemplar and schema are activated with the selection of a particular lexical concept, their forms are used to define unique trajectories through an endogenous perceptual–motor space that guides implementation. This space is not linguistic, reflecting its origin in the prespeech period. Central feedback control over production emerges with failures in communication and the development of a self-concept.
The goals of the current study were (a) to assess differences in child and adult pausing and (b) to determine whether characteristics of child and adult pausing can be explained by the same language variables. Spontaneous speech samples were obtained from 10 5-year-olds and their accompanying parent using a storytelling/retelling task. Analyses of pause frequency, duration, variation in durations, and pause location indicated that pause time decreased with retelling, but not with age group except when child and adult pausing was considered in its speech and language context. The results suggest that differences in child and adult pausing reflect differences in child and adult language, not in the cognitive resources allocated to language production.
The current study investigated whether variation in children's default articulation rate might reflect individual differences in the development of articulatory timing control, which predicts a positive correlation between rate and perceived clarity (motor skills hypothesis), or whether such variation is better attributed to speech external factors, which predicts that faster rates result in poorer target attainment (undershoot hypothesis). Two different speech samples were obtained from 54 typically developing children (5;2 – 7;11). Six utterances were extracted from each sample and measured for articulation rate and segmental duration. Fourteen adult listeners rated the utterances for clarity (enunciation). Acoustic correlates of perceived clarity, pitch, and vowel quality were also measured. The findings were that age-dependent and individual differences in children's default articulation rates were due to segmental articulation and not to suprasegmental changes. The rating data indicated that utterances produced at faster rates were perceived as more clearly articulated than those produced at slower rates, regardless of a child's age. Vowel quality measures predicted perceived clarity independently of articulation rate. Overall, the results support the motor skills hypothesis: Faster default articulation rates emerge from better articulatory timing control.