The relation between speech tempo, loudness, and fundamental frequency: an important issue in forensic speaker recognition

Abstract

In voice identification, the mean fundamental frequency is a powerful and by far the best known speaker-specific acoustic parameter. In some cases, however, large differences in fundamental frequency values in different speech samples from the same subject may occur. This observation gave rise to the hypothesis that this parameter may interact with others, particularly speech tempo and loudness, which may both attain extreme values under forensic circumstances. In an experimental investigation with a total of 50 subjects in two groups, no statistically significant relationship was found between speech tempo, loudness and voice fundamental frequency. Therefore no correction or normalising procedure need be applied prior to the assessment or interpretation of fundamental frequency means. The issue needs further investigation with spontaneous speech samples and material from casework.