Music and pitch perception of cochlear implant recipients

ii iii Users of cochlear implants (CIs) often achieve good performance in speech recognition, but report that music sounds unnatural and is often unrecognisable. This thesis reports experiments to determine the relationship between the perception by CI users of parameters related to music (and to tonal languages) and the parameters of the signals that give rise to them. For electrical stimulation by pulse trains, the perceived pitch decreases approximately linearly with the insertion depth in the cochlear of the place of stimulation. At low rates, perceived pitch also increases approximately logarithmically with the rate of pulse delivery, but it saturates at several hundred pulses per second. The perceived quality of sound is greater when low rates are applied towards the apex of the cochlear, and conversely. The thresholds for temporal jitter discrimination are lower at lower rates ranging from on average 30 % at 100 pulses per second (pps) to 50 % at 500 pps.