Pitch perception of complex tones and human temporal-lobe function

Sixty-four patients with unilateral temporal-lobe excisions as well as 18 normal control subjects were tested in a missing fundamental pitch perception task. Subjects were required to indicate if the pitch of a pair of tones rose or fell. The excisions encroached upon Heschl's gyri in some cases, whereas, in others, this region was spared. All subjects included for study were able to perform well on a control task in which complex tones including a fundamental were presented. Stimuli for the experimental task, which was procedurally identical with the control task, consisted of several harmonic components spanning the same spectral range, but without a fundamental. Only subjects with right temporal lobectomy in whom Heschl's gyri were excised committed significantly more errors than the normal control group on this task. Patients with left temporal-lobe lesions or with anterior right temporal-lobe excisions were unimpaired. These results suggest that Heschl's gyri and surrounding cortex in the right cerebral hemisphere play a crucial role in extracting the pitch corresponding to the fundamental from a complex tone.