Mismatch negativity (MMN) elicited by abstract regularity violations in two concurrent auditory streams.

The study investigated whether violations of abstract regularities in two parallel auditory stimulus streams can elicit the MMN (mismatch negativity) event-related potential. Tone pairs from a low (220-392 Hz) and a high (1319-2349 Hz) stream were delivered in an alternating order either at a fast or a slow pace. With the slow pace, the pairs were perceptually heard as a single stream obeying an alternating low pair-high pair pattern, whereas with the fast pace, an experience of two separate auditory streams, low and high, emerged.