NCJ Number
164928
Journal
Polygraph Volume: 25 Issue: 1 Dated: (1996) Pages: 15-34
Date Published
1996
Length
20 pages
Annotation
This study examined the feasibility of using audio pitch analysis and spectrum decomposition techniques to aid in the detection of deception following a numbers test.
Abstract
Audio recordings were made of 44 male subjects' responses during a peak-of-tension (POT) test. A Lafayette field polygraph was used to collect respiration, cardiovascular, and electrodermal responses for manual evaluation. Half of the examinees were programmed "deceptive" and half were programmed "truthful." The audio recordings of the subjects' responses were analyzed off-line using pitch and spectral analysis software to examine differences between truthful and deceptive "no" responses. Usable voice recordings were obtained from 28 of the original 44 subjects. No significant differences were found between the two groups on individual measures of pitch variation, response duration, or mean response energy. There was a significant concurrence rate between decisions made by pitch/energy analysis and an examiner, based on analysis of the test data. Significant differences were found between the number of correct decisions made by the examiner (79 percent) and by pitch/energy analysis (37 percent); however, no significant differences were found between the number of false positive decisions made by the examiner and by pitch/energy analysis (35 percent compared to 29 percent). Results thus show that no single human voice measure, as collected and evaluated in this study, reliably discriminated between truthful and deceptive responses. 8 figures and 12 references