Hemispheric lateralization during spectral envelope perception is dynamic and individualized

The spectral envelope is an important acoustic cue for vowel and consonant perception. Sensitivity to the spectral envelope is commonly studied with a spectral modulation detection task in which two co-occurring spectral cues (spectral envelope - SE, carrier frequency - CF) may be available. Neuroimaging studies indicate that spectral cues are often processed asymmetrically in the cortex, but it is unknown if such lateralization depends on perceptual weighting of the available cues. Here we simultaneously measured SE discrimination and electroencephalography (EEG) in young adult listeners in a single-interval, two-alternative task during passive and active attention conditions as well as in a separate perceptual decision-weights task. Using condition-on-a-single-stimulus (COSS) analyses, individual differences in perceptual weights of spectral cues (SE, CF) were obtained for each listener. EEG source localized results showed that hemispheric lateralization was dynamically modulated over time between left and right auditory cortices and that lateralization was dependent on individual perceptual weighting patterns for SE and CF.