Method for processing a brain wave signal (4) obtained from a person using a brain wave detector (5). One or more stimuli are applied to the person in which each of the one or more stimuli comprises a pseudo random noise component modulating the stimulus intensity. A brain wave signal (4) is detected after applying the one or more stimuli. The detected brain wave signal is processed to calculate which of the one or more stimuli is present in the detected brain wave signal using correlation techniques. The pseudo random noise component comprises a pseudo random noise sequence of the class of maximum length sequences, which are further modulated with twice their associated bit frequency.
