Experiment on Voice Identification

A two‐year experiment on voice identification through visual inspection of spectrograms was performed with the twofold goal of checking Kersta's claims in this matter [Nature 196, 1253–1257 (1962)] and testing models including variables related to forensic tasks. The 250 speakers used in this experiment were randomly selected from a homogeneous population of 25 000 males speaking general American English, all students at Michigan State University. A total of 34 996 experimental trials of identification were performed by 29 trained examiners. Each trial involved up to 40 known voices, in various conditions: with closed and open trials, contemporary and noncontemporary spectrograms, nine or six clue words spoken in isolation, in a fixed context and in a random context, etc. The examiners were forced to reach a positive decision (identification or elimination) in each instance, taking an average time of 15 minutes. Their decisions were based solely on inspection of spectrograms; listening to the identificati...