Progress Report No. 26 (2003-2004)
Speech Perception in Deaf Children with Cochlear Implants1
David B. Pisoni
Speech Research Laboratory
Department of Psychology
Bloomington, Indiana 47405
1 This work was supported by NIH-NIDCD Training Grant T32DC00012, NIH-NIDCD Research Grants R01DC00111, NIHNIDCD R01DC00064 to Indiana University and NIH Research Grant R01DC03100 to Central Institute for the Deaf. I would like to thank Miranda Cleary for her help and advice on all stages of the research described in this chapter. I would also like to thank Ann Geers, Chris Brenner and Mike Strube of CID for their help and assistance. I am also grateful to Steven Chin for his editorial comments on an earlier version of this paper.
Speech Perception in Deaf Children with Cochlear Implants
Abstract. Cochlear implants work well in many profoundly deaf adults and children. However, despite the success of cochlear implants in many deaf children, large individual differences have been reported on a wide range of speech and language outcome measures. This finding is observed in all research centers around the world. Some children do extremely well with their cochlear implant while others derive only minimal benefits after receiving their implant. Understanding the reasons for the variability in outcomes and the large individual differences following cochlear implantation is one ofthe most important problems in the field today. This chapter summarizes recent findings on the speech perception skills of deaf children following cochlear implantation. The results of these studies suggest that in addition to several demographic and medical variables, variation in children’s success with cochlear implants reflects fundamental differences in rapid phonological coding and verbal rehearsal processes which are used ina wide range of clinical outcome measures used to measure benefit following implantation.
Each week for the last 12 years I have traveled from my home in Bloomington to Riley Hospital for Children at the IU Medical Center in Indianapolis, a distance of some 60 miles each way, to work on an unusual clinical research project. I am part of a multidisciplinary team of basic and clinical researchers who are studying the development of speech perception and language skills of profoundly deaf children who have received cochlear implants. My colleague, Dr. Richard Miyamoto, a pediatric otologist and head and neck surgeon has been providing profoundly deaf adults and children with cochlear implants since the early 1980s when the first single-channel implants were undergoing clinical trials. Since the approval of cochlear implants by the FDA as a treatment for profound deafness, over 60,000 patients have received cochlear implants at centers all over the world (Clarke, 2003). A cochlear implant is a surgically implanted electronic device that functions as an auditory prosthesis for a patient with a severe to profound sensorineural hearing loss. It provides electrical stimulation to the surviving spiral ganglion cells of the auditory nerve bypassing the damaged hair cells of the inner ear to restore hearing in both deaf adults and children. The device provides them with access to sound and sensory information from the auditory modality. The current generation of multichannel cochlear implants consist of an internal multiple electrode array and an external processing unit (see Figure 1). The external unit consists of a microphone that picks up sound energy from the environment and a signal processor that codes frequency, amplitude and time and compresses the signal to match the narrow dynamic range of the ear. Cochlear implants provide temporal and amplitude information. Depending on the manufacturer, several different place coding techniques are used to represent and transmit frequency information in the signal. For postlingually profoundly...