Handedness and dichotic listening to nonverbal features of speech.

The assumption that pitch and loudness are processed in the right hemisphere was tested by comparing left-handers' with right-handers' performance on pitch and loudness discrimination tasks. Four groups of left-handers (20 subjects in each group) were dichotically presented either with digits varying in pitch or loudness or with pure tones varying in pitch. The subjects identified the digits, or the pitch and loudness variations, from both ears. Confirming the assumption, the data showed that the left-handers, who had no ear preference on any of these tasks, differed significantly from the right-handers, who, preferring the right ear for digit identification, preferred the left ear for the discrimination of the nonverbal features (pitch and loudness) of these digits.