May I Speak Freely? The Difficulty in Vocal Identity Processing Across Free and Scripted Speech

Sarah V Stevenage,Ashley E Symons,Greg J Neil,Rebecca Tomlin

doi:10.1007/s10919-020-00348-w

Sarah V Stevenage, Ashley E Symons + Show 2 more

Open Access

https://doi.org/10.1007/s10919-020-00348-w

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Abstract

In the fields of face recognition and voice recognition, a growing literature now suggests that the ability to recognize an individual despite changes from one instance to the next is a considerable challenge. The present paper reports on one experiment in the voice domain designed to determine whether a change in the mere style of speech may result in a measurable difficulty when trying to discriminate between speakers. Participants completed a speaker discrimination task to pairs of speech clips, which represented either free speech or scripted speech segments. The results suggested that speaker discrimination was significantly better when the style of speech did not change compared to when it did change, and was significantly better from scripted than from free speech segments. These results support the emergent body of evidence suggesting that within-identity variability is a challenge, and the forensic implications of such a mild change in speech style are discussed.

Highlights

A growing literature recognizes that the task of human identification involves both the ability to tell apart similar instances belonging to different individuals, and the ability to tell together different instances belonging to the same individual (Burton 2013)
Accuracy was recorded in each condition of the speaker discrimination task, and from this, measures of sensitivity of discrimination (d’) and response bias (C) were derived (Green and Swets 1966)
It was anticipated that speaker discrimination would be better when there was no change in speech style compared to when there was a change

Summary

Introduction

A growing literature recognizes that the task of human identification involves both the ability to tell apart similar instances belonging to different individuals, and the ability to tell together different instances belonging to the same individual (Burton 2013). In the context of the latter task, it is noted that the ability to recognize an individual, or to match one instance to another, is made considerably more difficult when those instances reflect a natural level of variability. This is exemplified by the difficulty in identifying an individual across changes in pose, lighting, camera angle, or even in the camera used to take the photograph (Young and Burton 2017). This difficulty is perhaps most starkly demonstrated in a face sorting task This difficulty is perhaps most starkly demonstrated in a face sorting task (Jenkins et al. Vol.:(0123456789)

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