Brain potentials as objective indexes of auditory pitch extraction from harmonics.

Complex tones such as vowels expressed by the human voice vary both in fundamental pitch (harmonic periodicity) and spectrum shape (vowel type). Three different pitches and spectra were combined into nine auditory stimuli. Latencies of cerebral evoked potential components decreased significantly as pitch increased, whereas they remained constant with spectrum shape. Because the fundamental (direct clue about pitch value) was purposely omitted from stimuli, these results reflect feature extraction processes. They also demonstrate that brain potentials can be used as objective indexes of perceived pitch.