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Conference Paper Open Access

Congruence plots and their applications in forensic voice comparison

Authors: Kelly, Finnian; Coy, Thomas; Alexander, Anil; Jessen, Michael

AES 2024 International Conference on Audio Forensics · Paper 5 · June 2024

Abstract

In forensic voice comparison, it is common for a practitioner to compare the same set of recordings using multiple speaker recognition systems or methods. The usual approach for comparing the results obtained from different systems or methods is to use performance metrics such as the Equal Error Rate (EER) or log-likelihood ratio cost (Cllr), and graphics like the Detection Error Tradeoff (DET) curve and Tippett Plot. While these metrics and graphics are very useful indicators of overall system discrimination and calibration, they do not indicate the level of agreement, or congruence, between the systems at the level of individual comparisons; for example, they do not inform as to whether System A and System B provide the same categorical output for an individual comparison. The congruence plot provides a visual representation of system agreement on a comparison-by-comparison basis by plotting the scores obtained for the same set of comparisons from two different systems against one another. This paper will introduce the congruence plot and its features within the Bio-Metrics software tool. The applications of congruence plots for voice comparison research and casework will then be illustrated through three forensically-relevant case studies.

Details

Published in
AES 2024 International Conference on Audio Forensics
Paper number
5
Publication date
June 17, 2024
Session subject
Forensic Voice Comparison; Forensic Automatic Speaker Recognition; Biometric Performance Assessement; Validation; Bio-Metrics
Affiliation
Oxford Wave Research Ltd., Oxford, United Kingdom; Oxford Wave Research Ltd., Oxford, United Kingdom; Oxford Wave Research Ltd., Oxford, United Kingdom; Department of Text, Speech and Audio, Bundeskriminalamt, Germany (See document for exact affiliation information.)
Type
Conference Paper