Phonetic Inventory Development in Young Cochlear Implant Users 6 Years Postoperation

Abstract

Increases in the phonetic inventories of a group of 9 children in the fifth and sixth years of experience with a cochlear implant are reported, extending a previous 4-year study (T. A. Serry & P. J. Blamey, 1999). Thirty-six out of 44 phones in Australian English reached the criterion of 50% correct in the conversational samples of 5 or more children. This level of performance corresponds to intelligible, but not completely natural, speech. The rate of improvement in the sixth year was slow, indicating a probable plateau in performance. The 8 phones that did not attain the 50% criterion in 5 or more children were /I, , , t, s, z, , θ/. Potential reasons for the slow development or nondevelopment of these phones include very low frequency of occurrence for /I, , / and the perceptual and articulatory characteristics of /t, s, z, , θ/. /t/ is also subject to a high degree of allophonic variation in the fluent speech of normally hearing speakers, probably accounting for much of the variability in its articulation in the conversational samples.