Examination of Prosody and Timbre Perception in Adults With Cochlear Implants Comparing Different Fine Structure Coding Strategies

Purpose: This study aimed to investigate whether adults with cochlear implants benefit from a change of fine structure (FS) coding strategies regarding the discrimination of prosodic speech cues, timbre cues, and the identification of natural instruments. The FS processing (FSP) coding strategy was compared to 2 settings of the FS4 strategy. Method: A longitudinal crossover, double-blinded study was conducted. This study consisted of 2 parts, with 14 participants in the first part and 12 participants in the second part. Each part lasted 3 months, in which participants were alternately fitted with either the established FSP strategy or 1 of the 2 newly developed FS4 settings. Participants had to complete an intonation identification test; a timbre discrimination test in which 1 of 2 isolated cues changed, either the spectral centroid or the spectral irregularity; and an instrument identification test. Results: A significant effect was seen in the discrimination of spectral irregularity with 1 of the 2 FS4 settings. The improvement was seen in the FS4 setting in which the upper envelope channels had a low stimulation rate. This improvement was not seen with the FS4 setting that had a higher stimulation rate on the envelope channels. Conclusions: In general, the FSP strategy and the 2 settings of the FS4 strategy provided similar levels in the perception of prosody and timbre cues, as well as in the identification of instruments.