Effect of Sound Familiarity on the Event-Related Potentials Elicited by Novel Environmental Sounds

The effect of sound familiarity was examined within the context of an event-related potential (ERP) novelty oddball paradigm. Brain electrical activity was recorded while subjects (16 young adults) listened to frequent tones, infrequent target tones, and infrequent novel environmental sounds. Subjects were instructed to press a button in response to the target tones only. There were 48 different novel sounds, 32 of which were repeated, and about two-thirds of which represented familiar sound concepts. The novel sounds elicited two ERP components, the novelty P3 and the P32. The novelty P3 was modulated by both repetition and familiarity, such that repeated familiar sounds elicited decreased novelty P3 amplitude at frontal sites, while repeated unfamiliar sounds elicited increased novelty P3 amplitude at posterior sites. This differential effect may reflect the operation of a neural network that distinguishes among different degrees of novelty.