Forensic analysis of auditorily similar voices

Abstract

Purpose: to verify contributions of acoustic spectrographic analysis in the forensic identification of speakers with auditorily similar voices, considering the distinctive behavior of acoustic parameters: formants of vowel “é”, of connected speech, mean fundamental frequency in Hz, linear prediction curve of vowel “é” and linear prediction curve area; and to propose an objective method to use the analyzed parameters. Methods: a quantitative, qualitative and descriptive study, conducted in Pernambuco on 16 pairs of male siblings, aged 18-60 years. The subjects recorded videos from which the audios were extracted, numbered and sent to three examiners, in two groups: older brothers and younger brothers, for perceptual-auditory pairing. The correct pairings, indicated by at least two examiners, were submitted to acoustic analysis. The statistical tests included Wilcoxon, Kruskal-Wallis and Bonferroni, with p<0.05. Results: the results of analyses of formants and the mean fundamental frequency were not enough to distinguish similar voices. Unprecedentedly, in the measurements of areas generated by the linear prediction curve graphs, a distinctive statistical significance was observed. Conclusion: it was concluded that, among the parameters studied, the measurements of areas of the linear prediction curve objectively indicated effectiveness in distinguishing speakers with auditorily similar voices.