Aural-perceptual speaker identification: problems with noncontemporary samples

Abstract

The degree to which speech and/or speech samples are noncontemporary is considered important to the speaker identification process. There are two dimensions to the problem; the first relates to the listener and, especially, to earwitness lineups. Here, the subject or witness is asked to make identifications at various times after having heard (but not having seen, of course) the speaker. It has been found that a person’s memory for a voice decays over time. In the second case, it is the samples of the speaker’s utterances which are temporally displaced. The prevailing opinion here has been that the use of non-contemporary speech samples poses just as difficult a challenge to the speaker identification process as does the decaying memory of a witness. Accordingly, research was carried out to test this possibility (Hollien and Schwartz, in press); it was found that the overall drop in correct identification over latencies from four weeks to six years was only about 15–25 per cent. It was not until the greatest of the time separations was studied (i.e., twenty years) that a substantial drop occurred (to 31 per cent). At this juncture, a number of questions arose; and three of them have been investigated. First, is listener gender important to the process; second, are the identification levels affected by the type of listeners employed and, finally, can external factors serve to differentially degrade listener performance? It was found that the first question could be answered in the negative and the second two in the affirmative. These findings should aid in clarifying some of the relationship between sample latency and identification accuracy.