Auditory speaker discrimination by forensic phoneticians and naive listeners in voiced and whispered speech

In whispered speech some important cues to a speaker's identity (e.g. fundamental frequency, intonation) are inevitably absent. In the present study we investigated listeners' ability to discriminate between speakers in short utterances in voiced and whispered speech. The performances of a group of 11 forensic phoneticians and a group of 22 naive listeners were compared in a binary forced-choice speaker discrimination task, with 48 same-speaker and 60 different-speaker pairs of short speech samples (<= 3 s) in each test. Listeners were asked to say whether the two voice samples in each pair were produced by the same or different speakers, and to give a certainty rating. The results showed that speaker discrimination is more difficult in whispered than in voiced speech, and that while the phoneticians were only slightly better than the naive listeners in voiced speech, the gap widened in whispered speech. Phoneticians were more cautious in their responses, but also more accurate than naive listeners. When unsure, the phoneticians tended to say two utterances came from different speakers, whereas naive listeners tended to say two utterances came from the same speaker. Results support the view that trained phoneticians may have an advantage over naive listeners in auditory speaker discrimination when the signal is degraded.