Impaired generalization of speaker identity in the perception of familiar and unfamiliar voices.

Abstract

In 2 behavioral experiments, we explored how the extraction of identity-related information from familiar and unfamiliar voices is affected by naturally occurring vocal flexibility and variability, introduced by different types of vocalizations and levels of volitional control during production. In a first experiment, participants performed a speaker discrimination task on vowels, volitional (acted) laughter, and spontaneous (authentic) laughter from 5 unfamiliar speakers. We found that performance was significantly impaired for spontaneous laughter, a vocalization produced under reduced volitional control. We additionally found that the detection of identity-related information fails to generalize across different types of nonverbal vocalizations (e.g., laughter vs. vowels) and across mismatches in volitional control within vocalization pairs (e.g., volitional laughter vs. spontaneous laughter), with performance levels indicating an inability to discriminate between speakers. In a second experiment, we explored whether personal familiarity with the speakers would afford greater accuracy and better generalization of identity perception. Using new stimuli, we largely replicated our previous findings: whereas familiarity afforded a consistent performance advantage for speaker discriminations, the experimental manipulations impaired performance to similar extents for familiar and unfamiliar listener groups. We discuss our findings with reference to prototype-based models of voice processing and suggest potential underlying mechanisms and representations of familiar and unfamiliar voice perception.

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

“…These spanned at least one full sentence so that unlike in some previous psychological voice discrimination studies, prosodic information could be used to make a matching decision. As has already been noted, previous studies have tended to use much shorter samples of speech (e.g., Lavan et al, ).…”

“…Task difficulty may increase the likelihood that lay listeners will attribute the variability to the same identity because they lack expert knowledge about how individual voices can vary across instances and are unable to isolate high‐level features of speech that are stable across utterances (Alexander et al, ; Leemann et al, ). From a perceptual point of view, the presence of intraspeaker variability is problematic for lay listeners trying to discriminate between identities (Lavan et al, ; Narayan et al, ; Wester, ). This is supported by the pattern of results observed in these experiments.…”

“…However, many previous voice discrimination studies testing nonexpert listeners have been motivated by interest in, for example, the effect of samples featuring different languages (Wester, , ; Winters et al, ) rather than potential forensic applications. Furthermore, these (Wester, , ; Winters et al, ) and other studies (e.g., Kreiman & Papcun, ; Van Lancker & Kreiman, ) have tested participants on speech samples created under very similar conditions (e.g., same speech type or no background noise) or have used vowel sounds (e.g., Lavan, Scott, & McGettigan, ) rather than full sentences. However, what is clear from the previous literature is that stimulus variability negatively affects voice discrimination performance.…”

“…However, what is clear from the previous literature is that stimulus variability negatively affects voice discrimination performance. Participants are less accurate when making judgments across different vocalizations (Lavan et al, ), different languages (Wester, ), and when linguistic content varies across to‐be‐compared samples (Narayan, Mak, & Bialystok, ).…”

A model of person perception from voices

“…Studies have shown that individuals with brain lesions are able to successfully complete speaker discrimination tasks using unfamiliar voices but cannot recognise familiar voices, and vice versa ( Van Lancker & Kreiman, 1987, Van Lancker, Cummings, Kreiman & Dobkin, 1988, Van Lancker, Kreiman, Cummings, 1989; see also Garrido et al, 2009 for a case study of developmental phonagnosia). This evidence is compelling, and conclusively demonstrates that discrimination is not a prerequisite for recognition (Van Lancker & Kreiman, 1987), however manipulations of voice familiarity and task type overlap in these studies (Lavan, Scott & McGettigan, 2016;Maguinness et al, 2017). It is thus unclear whether the findings reflect dissociations in familiar versus unfamiliar voice identity processing per se, differences in task demands, or aspects of both.…”