Could Your Voice Betray You?

The New York Times > Technology > Circuits: "Increasingly, lie-detector tests use voice stress analysis, a technology that has been around for decades but that has gained in popularity as the software at its heart continues to be refined.

Indeed, beyond its applications in law enforcement, proponents of the voice-based technology see its utility in everything from telemarketing to matchmaking. In Britain, a growing number of insurance companies have been using it to screen telephone claims in hopes of rooting out fraud - a goal they say has been borne out, both in fraud detection and in deterrence. One insurer, Admiral, says 25 percent of its car-theft claims have been withdrawn since it began using the system a year ago.

The several available applications of the technology work on the same basic principle: that the human voice contains telltale signals that betray a speaker's emotional state, like the intent to deceive. By analyzing small, often inaudible changes in the voice and visually displaying them on a computer screen, the techniques are thought to recognize not only veracity, but also a gamut of emotions ranging from anxiety to arousal.

With the Computer Voice Stress Analyzer (www.cvsa1.com/studies.php), for example, subjects are asked several control questions, like the color of the walls, to gauge normal vocal response levels. During the questioning, the interviewer sees the computer's interpretation of the responses immediately, although deciphering the charts generated by the computer requires training. Interviews or phone conversations can also be recorded for later analysis."