Where the science ends and the law begins: likelihood ratio-based forensic voice comparison in a $150 million telephone fraud

Authors

  • Phil Rose Australian National University

DOI:

https://doi.org/10.1558/ijsll.v20i2.277

Keywords:

forensic voice comparison, telephone fraud, likelihood ratio, F pattern, fundamental frequency

Abstract

The first use of likelihood ratios for the evaluation of forensic voice comparison evidence in a real trial in Australia is documented. Important steps in the process of estimating the strength of evidence – from acoustic-phonetic features in the utterances ‘yes’ and ‘not too bad’ – are described and explained. These comprise the nature and currency of likelihood ratios, choice of features, graphical demonstration of similarity and typicality of suspect and offender speech samples, and their multivariate likelihood ratio evaluation against a reference sample. Improvements in likelihood ratio estimation since the case are exemplified; in particular how to demonstrate that the approach actually works. The reception of the likelihood ratio-based evidence during the trial is used to highlight some problems in its rational evaluation by a court.

Author Biography

Phil Rose, Australian National University

Phil Rose was Reader at the Australian National University, where he taught Phonetics and Chinese Linguistics for 30 years. He has been a British Academy visiting professor at the University of Edinburgh’s Joseph Bell Centre for Forensic Statistics and Legal Reasoning, is chairman of the Forensic Speech Science Committee of the Australasian Speech Science and Technology Association and a member of the Australian Academy of Forensic Sciences. He has done forensic voice comparison case work on Australian English and varieties of Chinese for nearly 20 years.

Published

2013-12-17

How to Cite

Rose, P. (2013). Where the science ends and the law begins: likelihood ratio-based forensic voice comparison in a $150 million telephone fraud. International Journal of Speech, Language and the Law, 20(2), 277–324. https://doi.org/10.1558/ijsll.v20i2.277

Issue

Section

Articles