In Brief:
The aim of this study was to examine the effects of envelope-vocoder sound processing on listeners’ ability to discriminate changes in fundamental frequency (F0) in anechoic and reverberant conditions, and on their ability to identify concurrent vowels based on differences in F0. In the first experiment, F0DLs were measured as a function of number of envelope-vocoder frequency channels, with degree of simulated reverberation as a parameter. The results showed that reverberation was detrimental to F0 discrimination in conditions with fewer numbers of vocoder channels. In the second experiment, vowel identification was measured as a function of the F0 difference between two simultaneous vowels, with the number of vocoder channels as a parameter. Despite the reasonable F0DLs (< 1 semitone) with 24- and 8-channel vocoder processing, listeners were unable to benefit from F0 differences between the competing vowels in the concurrent-vowel paradigm. To the extent that vocoder processing simulates cochlear-implant processing, users of current implant processing schemes are unlikely to benefit from F0 differences between competing talkers when listening to speech in complex environments.
