Within the last 10 years, much research has been conducted using the PSE, which analyzes voice patterns. Researchers in stress are becoming increasingly aware of the possibilities presented by the analysis of stress through electronic analysis of the voice. The voice appears to be more closely related to the source of emotion than other means of physiological measurement. The muscles controlling speech patterns are apparently highly sensitive to stress states. The PSE is valuable primarily as an investigative tool. It must be attached to the subject to perform effectively. The interview can be conducted in a relaxed nonthreatening atmosphere, thus diminishing the likelihood of false positive results. Because the presence of stress does not necessarily indicate a subject is lying, the examiner must interpret the data measuring the stress carefully. Experience demonstrates that the data obtained using the PSE are as reliable as the data obtained using the polygraph, provided the examiner is skilled in interpreting stress responses. The methodology of the PSE is detailed, and a number of charts from clinical situations are presented as examples. Footnotes and 14 references are provided.