Auditory temporal resolution and speech performance in cochlear implant users

Abstract

It has been widely assumed that speech recognition depends, among other factors, on the auditory temporal resolution function. The present study was conducted to investigate the relationship between auditory temporal resolution and speech performance in nine Nucleus-22 cochlear implant (CI) listeners fitting with the SPEAK strategy. A modulation detection threshold task was used to evaluate auditory temporal resolution. Modulation detection thresholds were measured as a function of current levels. Results showed some marked difference in the temporal modulation function across CI users. Some patients showed increased modulation thresholds across the entire dynamic range while others showed thresholds asymptoted as low as 30% of the dynamic range. There is a strong correlation between consonant recognition scores and the mean modulation detection thresholds (across the entire dynamic range) among CI users. The correlation between the mean modulation detection thresholds and vowel recognition scores was relatively weak but was still significant. The results suggest that phoneme recognition, especially consonant recognition, depends highly on the patients’ capability to detect temporal modulation. One implication from the present results is that the high variability of speech performance is at least partly due to the differences in the temporal resolution of CI users. [Work supported by NIDCD.]