Mismatched distances from speakers to telephone in a forensic-voice-comparison case

Ewald Enzinger*, Geoffrey Stewart Morrison

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

In a forensic-voice-comparison case, one speaker (A) was standing a short distance away from another speaker (B) who was talking on a mobile telephone. Later, speaker A moved closer to the telephone. Shortly thereafter, there was a section of speech where the identity of the speaker was in question - the prosecution claiming that it was speaker A and the defense claiming it was speaker B. All material for training a forensic-voice-comparison system could be extracted from this single recording, but there was a near-far mismatch: Training data for speaker A were mostly far, training data for speaker B were near, and the disputed speech was near. Based on the conditions of this case we demonstrate a methodology for handling forensic casework using relevant data, quantitative measurements, and statistical models to calculate likelihood ratios. A procedure is described for addressing the degree of validity and reliability of a forensic-voice-comparison system under such conditions. Using a set of development speakers we investigate the effect of mismatched distances to the microphone and demonstrate and assess three methods for compensation.

Original languageEnglish
Pages (from-to)28-41
Number of pages14
JournalSpeech Communication
Volume70
DOIs
Publication statusPublished - 1 Jun 2015

Keywords

  • Distance mismatch
  • Forensic voice comparison
  • Likelihood ratio
  • Mismatch compensation
  • Validity Reliability

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