Consonant assimilation in early phonological development : a phonetic perspective

Consonant assimilation between noncontiguous consonants within words is one of the characteristic error patterns for children reported in observations of the earliest periods of speech acquisition. Previous analyses of consonant assimilation in young children have been based on formal phonological theories. However, phonological perspectives do not provide comprehensive explanations for potential mechanisms underlying children’s output forms when they are different from adult forms. The present study tests the hypothesis that functionalist phonetic approaches have the potential to provide a more comprehensive explanation for assimilation patterns in children’s speech output. Consonant assimilation patterns were observed from the onset of word use (approximately 12 months) to 36 months of age in ten English-speaking children. Assimilated forms in consonant-vowel-consonant (CVC) and consonant-vowel-consonant-vowel (CVCV) words produced by these children were analyzed. Predictions based on the Frame/Content perspective were evaluated relative to place and manner characteristics, vowel context, word level, and development over time. Results confirmed the prediction that motorically less available forms assimilate to more available forms in children acquiring ambient language speech patterns. Labial and coronal place of articulation more frequently motivated assimilation than dorsal. Stop and nasal manner of articulation more frequently motivated assimilation than fricative. The vowel context effects in assimilated forms were stronger for lingual consonants than labials and greater for CVCV more than CVC word forms. A word shape effect was observed related to place characteristics, direction of assimilation, and vowel context. A word position effect was observed for manner assimilations. Analysis of developmental trends revealed that children maintained a preference for motorically available forms in assimilations. The vowel context effects decreased over time. These findings suggest that patterns of consonant assimilation in these children are strongly motivated by behaviors already available within their production system capacities from the pre-linguistic babbling period, rather than being driven by patterns found in the targets they are attempting. Results also suggest that perceptual influences from language input may influence assimilation patterns to a lesser extent. Functionalist phonetic approaches that emphasize the understating of the production system and perceptual influences played a seminal role in understanding of children’s speech development relative to assimilation patterns.