Accuracy and perceptual asymmetry during dichotic pitch discrimination

Dichotic listening studies with normal right-handed listeners and with patients who have suffered focal cortical lesions suggest that the right hemisphere plays an important role in complex pitch discrimination. The perceptual asymmetry observed in normal listeners was studied using a dichotic recognition test consisting of 500-ms square wave tones with fundamental frequencies corresponding to the 12 semitones in the octave 261.63–523.25 Hz. A diotic recognition probe followed the presentation of each dichotic pair. The probe was identical to one of the dichotic items on 50% of the trials. On the remaining trials, the probe differed from one of the dichotic items by 0.25, 0.50, 0.75, or 1.00 semitone. Subjects who demonstrated a left ear advantage on this test were significantly more accurate in their pitch discrimination than were subjects who demonstrated a right ear advantage. Within each group, left and right discrimination functions were similar. The right ear advantage for pitch discrimination may reflect a sub-optimal strategy for processing pitch or for selecting dichotic signals. [Supported by NIH.]