Evaluation of a foreign speaker in forensic phonetics: a report

Abstract

. InABSTRACT Expert witnesses in phonetics find themselves more and more often in forensic situations in which they have to identify the voice of a speaker who does not speak their native language. Until recently, little has been known about the role which the nativelanguage background of the listener plays in such speaker identification tasks. In this report, several aspects of an experimental investigation on the influence of native-language background on speaker identification are reviewed. Results of a first experiment are reported and some follow-up experiments currently being carried out are described within that context.

The effect of removing linguistic information upon identifying speakers of a foreign language

“…However, if hit and false-alarm rate were actually identical it would mean that discrimination sensitivity would be zero, Le., listeners were not able to discriminate targets from foils when voices were speaking Spanish. This would be an interesting result for the research presented in this paper as well as in Schiller and Koster (1996) and Koster and Schiller (1997).…”

“…In a direct identification test, three different groups of listeners were asked to identify the voice of one speaker from a set of six different speakers (closed test). Listeners with a knowledge of German performed generally better than listeners without any knowledge of German (for details see Koster et al 1995;and Schiller and Koster 1996). We concluded that speaker identification involves not only purely phonetic information but also linguistic information.…”

“…Previous experimental research showed that a German target speaker was identified significantly better when listeners were native speakers of German, or native speakers of English who had some knowledge of German, than when they did not know the language of the target speaker (Schiller and Koster 1996). This result was taken as support for the hypothesis that familiarity with the language of the target speaker has a positive effect upon identifying that speaker.…”

“…This paper is about a control experiment that re-tested the results of the experiment reported in Schiller and Koster (1996). If it is the case that listeners use not only acoustic but also linguistic information when they are identifying a speaker, then listeners with different native-language backgrounds should perform equally well when linguistic information does not play a role.…”

“…In an earlier experiment (Koster et al 1995;Schiller and Koster 1996) we tested the hypothesis made by Goggin et al {1991} that the nativelanguage background of a listener plays an important role in SID. We showed that familiarity with the language of the speaker has an effect on the ability to identify a speaker.…”