CV syllables (kindly provided by Kresge, LSU) were presented dichotically to a 13‐year‐old boy prior to and post surgical section of the majority of hiscorpus callosum. Pre‐operatively no ear advantage was observed; however, after callosal section a clear right ear superiority emerged. Correct performance approximately doubled for the right ear and fell to change for the left ear. Voiceless CV's were reported correct more often than voiced, both prior to and post surgery. In addition, alveolars were more often reported correctly than labials, which in turn are reported more correct than velars. His single correct response performance was highest when pairs shared voicing preoperative and lowest when pairs shared place. Postoperatively sharing place still resulted in the lowest percent correct; however, performance was highest when pairs shared neither place nor voice. An analysis of pairs resulting in errors revealed that for the (1) voiceless/voiceless condition 16.6% errors occurred pre; and postoperatively, (2) voiced/voiced condition 21.0% errors occurred preop and 25.0% postop.; (3) voiceless/voiced condition 64.4% errors occurred preop and 58.4% postop. Thus error pattern did not change after section. These data suggest that callosal section results in suppression of the ear countralateral to the speech processor by removing the interhemisphere relay route.