Preattentive processing of complex sounds in the human brain

Processing of complex sounds in the human brain was studied with event-related potentials (ERPs) recorded from the scalp. In random stimulus sequences, one serial tone pattern, consisting of nine consecutive tones of different frequencies, was repeatedly presented to the left ear and another pattern to the right ear. Subjects attended either to the left-ear or right-ear patterns in order to detect in the attended ear occasional deviant patterns differing from the repeating standard pattern in the 3rd or 7th tone. Even undetected deviant patterns of the attended ear and deviant patterns of the unattended ear elicited the mismatch negativity component of the ERP. These results indicate preattentive processing of complex sounds in the human brain. (C) 1997 Elsevier Science ireland Ltd.