ISCA Workshop on Plasticity in Speech Perception (PSP2005)

Senate House, London, UK
June 15-17, 2005

Interspeaker Variation as the Long Term Outcome of Dialectally Varied Input: Speech Production Evidence for Fine-Grained Plasticity

James Scobbie

Queen Margaret University College, Edinburgh, UK

The linguistic systems used by native speakers are influenced by and reflect the input received; in particular during childhood from caregivers and peers. Different children in the same speech community (even siblings) can be expected to display individual flexibility reflecting input differences, cognitive differences and the demands of different interlocutor networks. Speakers can, however, also be expected to make recurrent functionally-oriented decisions, both in novel situations of contact and through mastering local systems (linguistic and sociolinguistic) which provide normative solutions to interacting with different groups.

Phonetic and phonological production data from 12 mutually-acquainted native young adult Shetlanders with differing input due to different parental backgrounds have been analysed Their parents were either Shetlandic, from elsewhere in Scotland, or from England. The fine phonetic detail of these speakers indicated plasticity in the formation of systems of contrast.

For example (Scobbie, in press), the VOT cue to the stop voicing contrast was found to demonstrate a high degree of interspeaker variation. The speakers' 'voiceless' stops were spread across the VOT continuum, but the distribution was non-arbitrary. First, it reflected experience: vernacular Shetlandic contrast systems (prevoiced /bdg/ vs. short lag /ptk/) were generally found in speakers whose parents were Shetlanders. Second, there was a functionally stable encoding of the contrast: a gradient inverse relation between the relative number of prevoiced tokens produced by an individual and their mean aspiration duration. However, two speakers used high numbers of prevoiced stops yet also long lag aspiration, a linguistically highly marked system albeit one which could be expected to function successfully both in general perceptual terms and specifically in the context of Shetlandic inter-speaker variation. Further ongoing analysis of vowel duration (a cue to post-vocalic consonant voicing) appears similarly plastic, showing similar patterns of fine-grained interspeaker variation. This new data will be presented.

Individuals were not limited to the use of unmarked oppositions, and the fine-detail specification of individuals' systems (as opposed to population-wide tendencies) do not provide evidence for a small inventory of discrete universal features/categories. Indexical and phonological cues were simultaneously present. The relevance of the results to exemplar models of the mental lexicon and the implications for the phonetics / phonology interface are discussed.

Full Paper

Bibliographic reference.  Scobbie, James (2005): "Interspeaker variation as the long term outcome of dialectally varied input: speech production evidence for fine-grained plasticity", In PSP2005, 56-59.