Temporal processing and speech recognition in cochlear implant users

Although the speech recognition performance of cochlear implant patients has steadily improved in recent years, considerable variability remains in implant patient outcomes. Here, we report on a correlation between cochlear implant patients' auditory temporal processing and speech recognition abilities. Modulation detection thresholds were measured as a function of stimulation level; phoneme recognition was also assessed. Results showed marked individual differences in the shape and absolute sensitivity of subjects' modulation threshold functions. Statistical analysis revealed a strong correlation between phoneme recognition scores and subjects' mean modulation thresholds, demonstrating the contribution of temporal processing to implant speech perception. In correlating a basic psychophysical measure to speech performance, these results should contribute toward improved speech processor design and rehabilitation tools for cochlear implant patients.