Spatiotemporal Characteristics of Cortical Responses to a New Dichotic Pitch Stimulus

Abstract

This study used behavioural measures and magnetoencephalography (MEG) to explore a binaural pitch, which is perceived when dichotic frequency modulation (FM) is applied to a band-limited noise stimulus. Although the stimulus contains no spectral, temporal or binaural components expected to produce a pitch, listeners were able to consistently match it to a pure tone. The MEG measures explored spatiotemporal characteristics of the cortical response evoked by the onset of this pitch within a noise. This had a latency of approximately 170 ms and was located in auditory cortex posterior to Heschl’s gyrus. In terms of spectral content, pitch onset was associated with a burst of activity in the theta and alpha frequency bands. Listeners’ ability to perceptually match the stimulus to a pure tone, and the similarity of the evoked response to previously described pitch-onset responses suggest that it does elicit a true pitch.