Studies bearing on generators of the electric and magnetic mismatch responses in humans to change in a repetitive sound are reviewed. It was concluded that the main contribution of the mismatch negativity (MMN) and of its magnetic equivalent MMNm, elicited even in the absence of attention, originates from auditory cortex on the supratemporal plane. In addition, those responses probably have one or two sources on the right lateral temporal cortex and, at least the MMN, a source also in the right frontal cortex. The activation caused by stimulus change in the sensory-specific cortex is, presumably, a manifestation of preperceptual change detection, whereas the frontal activation might be associated with conscious perception of, attention switch to, stimulus change.