Style variability in disfluency analysis for forensic speaker comparison


  • Lauren Harrington University of York
  • Richard Rhodes Universityof York/J. P. French Associates
  • Vincent Hughes University of York



disfluencies, disfluency analysis, TOFFA, forensic speaker comparison, speaking styles


Disfluencies are a natural part of speech, often going unnoticed by both speaker and listener. Recent research on disfluency profiles (McDougall and Duckworth 2017, 2018) shows that they contain speaker-specific information which could be analysed and compared in forensic speaker comparison (FSC) casework. Since samples in FSC tend to be mismatched for speaking situation and style, the present study investigates the consistency of speakers’ disfluency production across three forensically relevant tasks: a mock police interview, a paired conversation and a voicemail message. Disfluency production was found to differ significantly across tasks; in some cases, extreme within-speaker variation was observed. The results demonstrate that a speaker’s disfluency behaviour is unlikely to remain consistent across different situations. However, it was found that some individuals who demonstrated unusual production of a particular type of disfluency showed relatively consistent production of that type across all three tasks. Consequently, we recommend that disfluency analysis is not used in FSC where there are marked differences in speaking style or situation, unless distinctive disfluency production is observed in a sample.

Author Biographies

  • Lauren Harrington, University of York

    Lauren Harrington is a PhD student at the University of York, UK. Her doctoral research focuses on the transcription of forensic audio recordings and the effect of regional accent on transcription performance in both humans and machines. Her research is funded by the White Rose College of the Arts & Humanities (supported by the AHRC). She holds a BA (Hons) in French and Linguistics and an MSc in Forensic Speech Science, and carried out research on disfluency phenomena for her MSc dissertation. She is a research assistant on the project ‘Evaluating human and automated transcripts of speech recordings: implications for forensic linguistics’ for Aston Institute for Forensic Linguistics.

  • Richard Rhodes, Universityof York/J. P. French Associates

    Richard Rhodes is a senior forensic consultant at J. P. French Associates, a Forensic Speech and Acoustics Laboratory in York, UK. He acts as an expert witness in (mainly) criminal proceedings in court and produces reports concerning speaker comparison, transcription, questioned content analysis and other types of forensic phonetic casework. He is also Associate Lecturer in the Department of Language and Linguistic Science at the University of York where he teaches and supervises research.

  • Vincent Hughes, University of York

    Vincent Hughes is Lecturer in Forensic Speech Science at the University of York, UK. His research interests lie in forensic speech science, phonetics, phonology, sociophonetics and sociolinguistics. His current research focuses on understanding the bases and limitations of individual speaker characterisation and the relative contribution of acoustic, auditory and biological information. He is also interested in the application of the numerical likelihood ratio framework to the evaluation of speech evidence in forensic voice comparison cases. His doctoral research considered how the definition of the relevant population with regard to regional and social dimensions of variability and sample size affects the numerical estimation of the strength of evidence.


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How to Cite

Harrington, L. ., Rhodes, R. ., & Hughes, V. . (2021). Style variability in disfluency analysis for forensic speaker comparison. International Journal of Speech, Language and the Law, 28(1), 31–58.