Pitch ranking ability of cochlear implant recipients: A comparison of sound-processing strategies

Pitch ranking of sung vowel stimuli, separated in fundamental frequency (F0) by half an octave, was measured with a group of eleven Nucleus 24 cochlear implant recipients using different sound coding strategies. In three consecutive studies, either two or three different sound coding strategies were compared to the Advanced Combinational Encoder (ACE) strategy. These strategies included Continuous Interleaved Sampling (CIS), Peak Derived Timing (PDT), Modulation Depth Enhancement (MDE), F0 Synchronized ACE (F0Sync), and Multi-channel Envelope Modulation (MEM), the last four being experimental strategies. While pitch ranking results on average were poor compared to those expected for most normal hearing listeners, significantly higher scores were obtained using the MEM, MDE, and F0Sync strategies compared to ACE. These strategies enhanced coding of temporal F0 cues by providing deeper modulation cues to F0 coincidentally in time across all activated electrodes. In the final study, speech recognition tests ...