A method and apparatus for use in controlling a device or process. The first step of the method involves attaching a detector ( 20 ) adapted to detect mechanical vibrations to a person's head ( 22 ). A second step involves detecting mechanical vibrations elicited by sudden contact of upper teeth ( 24 ) and lower teeth ( 26 ). A third step involves using the mechanical vibrations to trigger a signal to control operation of a device or process ( 36, 80, 82, 84, 86, 88, 90 ).