Statistical models in forensic voice comparison

Geoffrey Stewart Morrison, Ewald Enzinger, Daniel Ramos, Joaquín González-Rodríguez, Alicia Lozano-Díez

Research output: Chapter in Book/Published conference outputChapter (peer-reviewed)peer-review


This chapter describes a number of signal-processing and statistical-modeling techniques that are commonly used to calculate likelihood ratios in human-supervised automatic approaches to forensic voice comparison. Techniques described include mel frequency cepstral coefficients (MFCCs) feature extraction, Gaussian mixture model - universal background model (GMM-UBM) systems, i-vector - probabilistic linear discriminant analysis (i-vector PLDA) systems, deep neural network (DNN) based systems (including senone posterior i-vectors, bottleneck features, and embeddings / x-vectors), mismatch compensation, and score to likelihood ratio conversion (aka calibration). Empirical validation of forensic voice comparison systems is also covered. The aim of the chapter is to bridge the gap between general introductions to forensic voice comparison and the highly technical automatic speaker recognition literature from which the signal-processing and statistical-modeling techniques are mostly drawn. Knowledge of the likelihood ratio framework for the evaluation of forensic evidence is assumed. It is hoped that the material presented here will be of value to students of forensic voice comparison and to researchers interested in learning about statistical modeling techniques that could potentially also be applied to data from other branches of forensic science.
Original languageEnglish
Title of host publicationHandbook of Forensic Statistics
EditorsD.L. Banks, K. Kafadar, D.H. Kaye, M. Tackett
PublisherCRC Press
ISBN (Print)9781138295407
Publication statusPublished - 28 Sept 2020

Bibliographical note

This is an Accepted Manuscript of a book chapter published by CRC Press in Handbook of Forensic Statistics on 28 Sept 2020, available online:


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