Case study: Speech production following cochlear implantation in a postlingually deafened adult

Abstract

While cochlear implants are designed primarily to aid speech perception, some aspects of speech production may improve post-implant in postlingually deafened speakers. Postural parameters such as average SPL may change immediately; phonemic parameters such as place changes allowing [s, ∫] to be distinguished may continue to change for two years or more post-implant [Matthies et al., J. Acoust. Soc. Am. 96, 1367–1373 (1994)]. In this paper we describe a female subject who received a cochlear implant following a progressive hearing loss from age 5. She became profoundly deaf at age 34, and was implanted at age 35 with a Nucleus CI24M. She was recorded saying an extensive speech corpus pre-implant and at intervals post-implant. Pre-implant, she had a very weak and creaky voice quality, and /s,z/ were consistently produced as silence, or one of [t, d, θ, ð, t∫]. Defining parameters to characterize the errors in manner is not straightforward, however. She received some speech therapy post-implant; her voice quality gradually improved, but the /s,z/ errors persisted. Her aided hearing levels and sentence perception results at 18 months are excellent. However, her Speech Perception Audiometry and consonant confusion results demonstrate difficulties and may help explain the continued [s,z] production problems. [Research funded in part by EPSRC.]