Earwitnesses: effects of speech duration, retention interval and acoustic environment

Abstract

AbstractAn experiment was conducted to investigate the reliability of voice lineups. More specifically, the experiment was designed to look into the effects of retention interval (an immediate test or after a week), speech duration (30 or 70 s) and acoustic environment (indoors or indoors and outdoors) on speaker identification accuracy. In addition, the relation between confidence assessments of both participants and test assistant on the one hand and identification accuracy was explored. A total of 361 participants heard the target voice in one of four exposure conditions (short or long text and speech samples recorded only indoors or indoors and outdoors). Half the participants were tested immediately after exposure to the target voice and half 1 week later. The results show that the target was correctly identified in 42% of cases. In the target‐absent condition there were 51% false alarms. Acoustic environment did not affect identification accuracy. There was an interaction between speech duration and retention interval in the target‐absent condition. When listeners were tested after a week, they made fewer false identifications if the speech sample was long. No effects were found when participants were tested immediately. Only the confidence scores of the test assistant had predictive value. Taking the confidence score of the test assistant into account therefore increases the diagnostic value of the identity parade. Copyright © 2004 John Wiley & Sons, Ltd.