Forensic voice comparison using likelihood ratios based on polynomial curves fitted to the formant trajectories of Australian English /aI/

Authors

  • Geoffrey Stewart Morrison Australian National University

DOI:

https://doi.org/10.1558/ijsll.v15i2.249

Keywords:

forensic speaker recognition, likelihood ratio, polynomial, curve fitting, formant trajectory, diphthong

Abstract

Earlier studies have indicated that information regarding speaker identity can be extracted from the dynamic spectral properties of diphthongs. It is widely accepted that likelihood ratios provide the logically and legally correct method for the evaluation of forensic evidence. Some studies have conducted likelihood-ratio analyses based on simple models of the dynamic formant properties of diphthongs (e.g., dual-target model), and others have used more sophisticated polynomial curve fitting models of the dynamic formant properties of diphthongs but have not conducted likelihood ratio analyses. The present study examines the strength of evidence which can be produced by a likelihood ratio analysis based on the coefficients of polynomial curves fitted to the formant trajectories of Australian English /aI/ tokens. A cubic polynomial model offers a substantial improvement over the dual-target model.

Author Biography

Geoffrey Stewart Morrison, Australian National University

GEOFFREY STEWART MORRISON holds a PhD from the University of Alberta. He is a Research Associate in Forensic Speaker Recognition at the School of Language Studies, Australian National University, where he is currently working on an Australian Research Council funded project aimed at combining traditional and automatic approaches to forensic speaker recognition. His previous research has included statistical modelling of the perception of vowel inherent spectral change.

Published

2009-02-15

How to Cite

Morrison, G. S. (2009). Forensic voice comparison using likelihood ratios based on polynomial curves fitted to the formant trajectories of Australian English /aI/. International Journal of Speech, Language and the Law, 15(2), 249–266. https://doi.org/10.1558/ijsll.v15i2.249

Issue

Section

Articles