VOCAL INDICATORS OF PSYCHOLOGICAL STRESS

People have been attempting to assess the presence, absence, and/or magnitude of psychological stress from the speech and voice production of other individuals since primitive man added a cognitive overlay to his repertoire of oral signals. Indeed, it is quite probable that crude assessments of this type were attempted even before organized communicative sounds existed among our species. Quite obviously, these analyses were (and are) attempted for a rather substantial number of reasons, some of which are within the scope of forensic psychology. They include assessment of the presence and magnitude of such emotional states as hostility, aggressive intent, fear, and anxiety; behaviors such as deception or divisiveness; even psychopathological states can be included under this rubric. There is little question but that emotional and/or behavioral conditions of this type exist and their detection is of consequence. For example, it can be important for monitor personnel to be able to determine the levels and types of stress present in individuals who are physically separated from them-i.e., pilots, astronauts, aquanauts, etc.-irrespective of the message content of the spoken interchange. It is desirable also for a worker at a crisis control center to be able to tell if the caller actually is going to commit suicide from the ,manner in which he or she communicates. Knowledge of the acoustic/temporal speech clues that correlate with psychosis can be important to clinical personnel. In short, many instances can be cited where information about the behavioral intent or emotional states of an individual could be useful. Law enforcement personnel, also, would find systems or procedures that could reliably identify the emotions felt by the talker, the presence of lying, or the presence/absence of psychosis helpful in their work. Moreover, if such procedures could be carried out rapidly, on-scene decisions sometimes could be made that currently are not possible. In any case, it would appear that the activities of law enforcement, intelligence, and security agencies all would benefit if the various stress states cited above could be instrumentally identified. Before any attempt is made to discuss the possible vocal correlates of psychological stress, it will be necessary to clarify a number of terms. The concept of stress is, in and of itself, quite difficult to define. For example, sometimes this term is used to refer to the emphasis patterns an individual uses when uttering a spoken message, and, of course, the ways by which