Summary

A new form of lie detector that works by voice analysis and which can be used without a subject's knowledge has been introduced in Britain. They are numbers of ways in which this machine can be used and the objection to its use. The vibration of the vocal chords and resonance of cavaties inside the head; these is a third component caused by vibration of the muscles inside the mouth and throat. These have a different meaning, either stress or dishonesty. The detector only detect caused by stress, not dishonesty. Three steps are suggested to overcome this dissiculty. The first one is the subject is supposed to see a full list of the question in advance. Second, there are neutral questions and one to which the subject is specially asked to lie. Third, if an individual shows stress on a vital question, then additional questions must be asked to ensure that this does not reflect an earlier theft or the subject's knowledge of someone responsible.