Familiarity affects environmental sound processing outside the focus of attention: An event-related potential study

ObjectiveThis study investigated the influence of the familiarity of an environmental sound on sound processing outside the focus of attention.MethodsBy comparing ERPs elicited by a familiar, animal sound and an acoustically matched, but unfamiliar, complex sound, three issues were addressed: (a) general differences in the processing of the familiar and the unfamiliar sound, (b) influences of sound familiarity on the processing of deviants unrelated to familiarity and (c) familiarity-specific processing depending on the sound context. Participants watched a silent, subtitled movie.ResultsThe familiar sound elicited a centro-parietal enhancement of the N1, a frontocentrally enhanced P2 and an additional P250. Auditory deviance processing elicited by deviants in sound location was not influenced by the familiarity of the sounds. However, after an involuntary switch of attention to the deviant, an N400-like deflection indicated enhanced semantic analysis of the familiar deviant. Familiarity-specific ERP effects as a consequence of the sound context occurred between 300 and 500 ms after stimulus onset.ConclusionWhereas familiarity of an environmental sound elicited enhanced stimulus processing before 300 ms, influences of the sound context were observed subsequent to 300 ms.SignificanceFamiliarity of a complex environmental sound influences several stages of auditory processing outside the focus of attention.