Forensic Voice Comparison

Selected Publications and Other Documents

    • The first likelihood ratio-based forensic voice comparison on female voices, and the first forensic use of Gaussian mixture models on traditional features, are described. A GMM-UBM LR-based comparison is performed on the first three formants of the five long monophthongs of 20 General Australian English female speakers in non-contemporaneous recordings separated by one to five weeks. Comparison with logistic-regressively fused multivariate likelihood ratios from the same data shows both systems perform well, but the latter is superior in both EER and log likelihood ratio cost.

  • Morrison, G. S. , et al. (2009) Making demonstrably reliable forensic voice comparison a practical everyday reality in Australia. Linkage Project Application.

    • To make forensic voice comparison a practical everyday reality in Australia, for use in police investigations and for presentation of evidence in court, forensic scientists must have a practical and demonstrably reliable forensic-voice-comparison system including a large representative database of Australian English voices. In collaboration with Australian police forensic laboratories and other partners we will develop and test such a system, improving on existing systems by combining the strengths of acoustic-phonetic and automatic approaches. The system will comply with the strictest international standards for the admissibility of scientific evidence in court, using the same evaluative framework as is applied to DNA.

  • Morrison, G. S. (2009) The place of forensic voice comparison in the ongoing paradigm shift. The 2nd International Conference on Evidence Law and Forensic Science Conference Thesis (Vol. 1, pp. 20–34). Beijing, China: The Key Laboratory of Evidence Science of the Ministry of Education (The Institute of Evidence Law and Forensic Science, China University of Political Science and Law).

    • We are in the midst of what Saks & Koehler (2005) have called a paradigm shift in the evaluation of evidence in the forensic comparison sciences. This is a shift to requiring that the evaluation of forensic evidence actually be scientific, including that the reliability of methodologies be testable, and requiring that forensic evidence be evaluated and presented to the courts in a logically correct manner. Reliability was a primary concern in the US Supreme Court’s Daubert decision in 1993. The logically correct evaluation and presentation of the weight of forensic evidence was a primary concern in a number of court cases in the United Kingdom including the Appeal Court of England and Wales’ 1996 ruling on the presentation of DNA evidence in R v Doheny & Adams. In the US National Research Council’s report to Congress released in February 2009 current practice in the evaluation of nuclear DNA evidence is held up as a model to emulate, and current practices in other branches of forensic science are subject to sometimes severe criticism. In the present paper I examine the place of forensic voice comparison in the ongoing paradigm shift. Over the last decade a small number of forensic-voice-comparison researchers have been working in the post-shift paradigm. They have adopted the likelihood-ratio framework for the evaluation of forensic evidence, the same framework as used in DNA analysis. I provide a brief description of the likelihood-ratio framework, followed by a brief history of the adoption of the likelihood-ratio framework for forensic voice comparison by the research community, and by the forensic practitioner, law-enforcement, and judicial communities.

    • A revised version of this paper is: Morrison, G. S. (2009) Forensic voice comparison and the paradigm shift. Science & Justice, 49, 298–308.

  • Rose, P., & Morrison, G. S. (2008) 对英国关于法庭话者比较的立场声明的回应. Translation by Cuiling Zhang 张翠玲. Unpublished Manuscript

    • 我们明确了英国提出的建议中的三个根本缺陷。首先,将语音特征作为离散的和不变的特征来对待,就象DNA一样,其结果是很难将该方法付诸实现。其次,我们指出了文章前后的矛盾之处,即先是禁止后又允许使用证据的假设概率,承认缺少支持信息却又使用特殊性表述。第三,缺少关于一致性和特殊性的评价方法并没有帮助事实裁定者对其进行解释。我们反对英国体系在声明的前言中宣称的:“在概念水平上,与当前提供DNA证据时使用的方法一致”(p. 138) 的观点。最后,我们还要指出的是,英国立场声明并没有达到它的目标。但是,值得称赞的是,“它通过现代思想将法庭语音比较和其它法庭科学结合起来”(p. 137)。使用似然率方法才是法庭比较证据评价的现代思想。我们还是鼓励世界范围内的所有法庭语音比较研究人员和检验人员尽快采用量化的似然率方法为标准。