Individual patterns of disfluency across speaking styles

a forensic phonetic investigation of Standard Southern British English

Authors

  • Kirsty McDougall University of Cambridge
  • Martin Duckworth Independent researcher

DOI:

https://doi.org/10.1558/ijsll.37241

Keywords:

fluency behaviour, disfluency features, TOFFA, individual differences, speaker-specificity, speaking style

Abstract

Features of speech related to fluency such as filled and silent pauses, sound prolongations, repetitions and self-interruptions exhibit considerable variation among speakers, yet the speaker-specificity of such features has received little attention inforensic phonetic research. The present study investigates the extent to which individual differences in disfluency behaviour are preserved across different speaking styles, a key concern for forensic speaker comparison cases. Disfluency phenomena in the speech of 20 male speakers of Standard Southern British English undertaking a simulated police interview task are compared with the occurrence of the same set of phenomena in the speech of the same speakers participating in a telephone conversation with an 'accomplice'. The speakers' disfluency features are analysed using TOFFA 'Taxonomy of Fluency Features for Forensic Analysis' (McDougall and Duckworth 2017). Individuals exhibit a wide range of variation in their overall rate of production of disfluency features, and these rates are relatively consistent within-speaker across interview and telephone styles. The results for each specific disfluency feature type also show patterns of relatively consistent behaviour within-speaker across-style for most features. For both interview and telephone styles, discriminant analyses based on speaker profiles of disfluency features demonstrate that disfluency features carry speaker-specific information which could be considered alongside other analyses in forensic speaker comparison cases.

Author Biographies

  • Kirsty McDougall, University of Cambridge

    Kirsty McDougall is an Affiliated Lecturer in Theoretical and Applied Linguistics at the University of Cambridge and a Fellow of Selwyn College, Cambridge. Her research interests range across speaker characteristics, theories of speech production, phonetic realisation of varieties of English, and forensic phonetics. Among other things, her forensic phonetic research has focused on speaker-distinguishing properties of dynamic features of speech, perceived voice similarity and its implications for the selection of foils for voice parades, and the development of techniques for analysing individual differences in disfluency behaviour. She is a member of IAFPA.

  • Martin Duckworth, Independent researcher

    Martin Duckworth is a qualified speech and language therapist and has an MA in Phonetics and Linguistics. He worked for over 30 years as a therapist specialising in adults who stutter. He also taught phonetics, and speech therapy. Alongside this work he undertook forensic speaker comparisons until his retirement from casework in 2016. He is now an independent researcher with a specific interest in the application of fluency measurement in forensic casework. He is a member of IAFPA.

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Published

2018-12-07

Issue

Section

Articles

How to Cite

McDougall, K., & Duckworth, M. (2018). Individual patterns of disfluency across speaking styles: a forensic phonetic investigation of Standard Southern British English. International Journal of Speech, Language and the Law, 25(2), 205-230. https://doi.org/10.1558/ijsll.37241