Maximum length sequence applied to the measurement of brainstem auditory evoked responses.

An evoked response may be assumed to consist of synchronous electrical activities of groups of neurons in response to a stimulus. Unfortunately, this response is usually weak and often masked by the background EEG activity generated spontaneously by the brain. In order to extract the embedded evoked response we have employed the theory of maximum length sequence, assuming only a temporal linearity of the system from which measurements are taken. The technique has been applied successfully with the aid of a microcomputer. The system also supports the same measurement by a conventional averaging technique. The results of the two are compared, indicating the advantages of the maximum length technique: improved signal-to-noise ratio, repeatability and speed.