Covert contrast in the acquisition of English /ɹ/: a case study

Abstract

In this thesis I examine the potential role of covert contrast (the phenomenon by which a phonological contrast produced by a language learner falls below the threshold of perception of adult speakers of this language) in the development of one child learning the contrast between /ɹ/ and /w/ in English. More specifically, using a longitudinal corpus documenting the development of American English by one child learner, I compare data obtained by impressionistic means of phonetic transcription against acoustic measurements of the same speech tokens. As we will see, the results from both the transcription data and the acoustic measurements mirror one another in ways that undermine the claim that covert contrast represents a necessary stage in acquisition (Scobbie et al. 1996). Additionally, the current study reveals a disparity in the time of acquisition for /ɹ/ in coronal stop-initial onsets vs. all other onset environments which highlights the influence of articulatory factors on the production of /ɹ/ across different phonological contexts. Finally, the acoustic component of the study uncovers what can be termed a ‘covert allophone’ in the case of /w/ in that same coronal-initial complex onset environment. I conclude this thesis with a discussion of both the theoretical and methodological implications for future research on the development of phonological contrasts by children.