Brain activity during selective listening to natural speech.

Human brain functions involved in selective attention to particular sounds have been studied extensively with non-invasive measurements of electro-magnetic and hemodynamic brain activity. Here we review studies indicating that selection of the attended sounds for further processing occurs in the auditory cortex. The exact locus of this selection process in the auditory cortex appears to depend on the auditory attribute, i.e., location or pitch, separating the attended sounds from the irrelevant ones. Recent neuroimaging studies extend this finding from processing of non-speech sounds to attentional selection of relevant speech differing by its location or speaker identity from concurrent irrelevant speech. These studies suggest also that selective listening to speech depends less on prefrontal control functions than other kinds of listening tasks demanding selective attention.