Forensic voice discrimination by lay listeners: The effect of speech type and background noise on performance

Abstract

In forensic settings, lay (nonexpert) listeners may be required to compare voice samples for identity. In two experiments we investigated the effect of background noise and variations in speaking style on performance. In each trial, participants heard two recordings, responded whether the voices belonged to the same person, and provided a confidence rating. In Experiment 1, the first recording featured read speech and the second featured read or spontaneous speech. Both recordings were presented in quiet, or with background noise. Accuracy was highest when recordings featured the same speaking style. In Experiment 2, background noise either occurred in the first or second recording. Accuracy was higher when it occurred in the second. The overall results reveal that both speaking style and background noise can disrupt accuracy. Although there is a relationship between confidence and accuracy in all conditions, it is variable. The forensic implications of these findings are discussed.

Unimodal and cross-modal identity judgements using an audiovisual sorting task: Evidence for independent processing of faces and voices

“…For voice identity matching, accuracy was also relatively low: These findings echo previous voice identity sorting studies that include within-person variability (i.e. different categories of speaking style / non-verbal vocalisation; Lavan, et al, 2016;Smith et al, 2019), further highlighting the difficulties that such within-person variability can pose to accurate identity perception.…”

“…hairstyle or lighting for faces, versus expressiveness or audience accommodation effects for voices) but the result is the same. Thus, while accuracy for unfamiliar face matching and unfamiliar voice matching can be relatively high, within-person variability introduces errors (Bruce et al, 1999;Lavan, Scott, & McGettigan, 2016;Smith, Baguley, Robson, Dunn, & Stacey, 2019). In identity sorting tasks, where participants are instructed to sort a set of naturally varying stimuli into different identities, it is common to incorrectly perceive multiple images or recordings of the same unfamiliar person as representing a number of different people (Jenkins, White, Van Montfort, & Burton, 2011;Lavan, Burston, & Garrido, 2019;Stevenage, Symons, Fletcher, & Coen, 2020).…”

Performance of Typical and Superior Face Recognisers on a Novel Interactive Face Matching Procedure

“…However, in face matching experiments, participants complete a series of trials, and therefore encounter multiple stimuli. A criticism of using calibration to analyse data from multiple trial experiments such as face matching is that it involves aggregating data, and therefore ignoring variability at the stimulus level (see Smith, Baguley, Robson, Dunn, & Stacey, 2019). This source of variability may however be relevant to the results (Clark, 2012;Judd, Westfall, & Kenny, 2012).…”

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

“…More specifically, scripted speech was noted to be more rapid and free from hesitation compared to free speech when story-telling (Levin et al 1982), especially in the latter part of an utterance (Remez et al 1986). In terms of the impact of speech style when processing vocal identity, there is value in considering the results of Smith et al (2019) who examined speaker discrimination as speech style varied from scripted to free speech. Across two experiments, their results revealed significantly worse performance and significantly lower confidence when speech style changed from scripted to free speech, compared to a baseline condition in which both clips features scripted speech.…”