Effects of distorted auditory feedback on speech.

Abstract

A research program for acoustically measuring changes in speech production will be described. Here, F0 and spectrographic measurements target acoustic correlates of consonant, vowel, and syllabic stress features in 45 phonemically balanced words. To date, 5 Nucleus-22 multichannel cochlear implant patients have participated (at least) prestimulation, immediately after stimulation, 3–6 months after stimulation, and 1-year after stimulation. Commonalities among patients include: a rapid increase and stabilization of F0 (in females) to normal values; immediate and continuing changes in vowel and syllable durations and in relative amounts of breathy noise and low-frequency energy, gradual changes in vowel formant frequencies with movement still observed at 1 year; and changes in consonant properties (such as F1 cutback for voiceless stops) emerging for the first time at 1 year. Results relate to (1) the potential role of critical periods in the effect of auditory feedback on speech habits, (2) the relative susceptibility of speech features to modification, and (3) the likely auditory parameters available from Nucleus-22 WSP III stimulation. [Work supported by NIDCD.]