LABELING OF MUSICAL INTERVAL SIZE BY COCHLEAR IMPLANT PATIENTS AND NORMALLY HEARING SUBJECTS

Objective: To compare the performance of cochlear implant patients and normal-hearing subjects on a musical interval labeling task, and to d etermine whether information regarding musical interval size is availa ble to cochlear implant patients under realistic everyday listening co nditions. Design: Two Nucleus cochlear implant patients listened to mu sical intervals that consisted of systematic variations of electric pu lse rate on single bipolar intracochlear electrode pairs whereas norma l-hearing listeners were presented with the acoustical analog of these stimuli. Subjects labeled the intonation quality of the stimulus inte rvals (''flat,'' ''sharp,'' or ''in tune''), relative to their memory for specific intervals abstracted from familiar melodies. The cochlear implant patients, in addition, performed this task with realistic aco ustical musical stimuli. Results: The interval labeling behavior of co chlear implant subjects, at low pulse rates, was similar to that of no rmal-hearing subjects. Furthermore, pitch interval information does no t appear to be available to cochlear implant subjects when they are li stening to acoustical stimuli via their speech processors. Conclusions : Temporal information appears to be sufficient for the perception of musical pitch. Encoding strategies that are highly successful isl rest oring speech understanding do not necessarily provide information rega rding melodic pitch interval size.