Perception and production of /r/ allophones improve with hearing from a cochlear implant

Abstract

While variations in tongue shape for /r/ occur in different contexts, they normally result in only small changes in the primary acoustic cue (lowered F3). It was hypothesized that deaf speakers would show larger allophonic variation than normal-hearing speakers and that auditory feedback from a cochlear implant would reduce that variability. In this study, acoustic variation of stop and stop+/r/ tokens was evaluated pre- and post-implant (n=8) and once in normal-hearing controls (n=8). Measures included (1) r-variation: distance from the center of the distribution defined by the F3 transition and the value of F3 minus F2 at the /r/-vowel boundary for wabrav, wadrav, and wagrav tokens (2) vowel variation: distance from the center of F1, F2 for the second /a/ in wabav, wadav, and wagav tokens and (3) pairwise r-variation normalized by vowel variation. Pre-implant, seven of eight speakers had significantly greater normalized /r/ variation than the hearing speakers mean. Post-implant, seven of eight speakers had normalized /r/ are variation that was not different from the control mean. Implant users perception and production of stop and stop+/r/ blend productions improved; however, their /b-br/ and /g-gr/ contrast distances were still smaller one-year post-implant than the controls. [Research supported by NIDCD.]