Factors Associated with Development of Speech Perception Skills in Children Implanted by Age Five

Abstract

In Brief Objective This study investigated factors contributing to speech perception outcomes in children with prelingual deafness after 4 to 7 yr of multichannel cochlear implant use. The analysis controlled for the effects of child, family and implant characteristics so that educational factors most conducive to maximum implant benefit could be identified. Design One hundred eighty-one 8- and 9-yr-old children from across the US and Canada who received a cochlear implant by age 5 were administered a battery of speech perception tests. Type and amount of educational intervention since implantation constituted the independent variables. Characteristics of the child, the family, and the implant itself constituted intervening variables. A series of multiple regression analyses determined the amount of variance in speech perception ability accounted for by the intervening variables and the amount of additional variance attributable to independent variables. Results The children achieved an average level of about 50% open-set speech perception through listening alone and almost 80% through lipreading and listening together, but with scores for individual children ranging from 0 to 100% correct. Over half of the variance in speech perception scores was predicted by characteristics of the child, family, implant and educational program. Significant predictors of good speech perception included greater nonverbal intelligence, smaller family size, longer use of the updated SPEAK/CIS processing strategy, a fully active electrode array, greater electrical dynamic range between threshold and maximum comfort level, and greater growth of loudness with increasing stimulus intensity. After the variance due to these variables was controlled, the primary rehabilitative factor associated with good speech perception skill development was educational emphasis on oral-aural communication. Conclusions Children with profound hearing loss achieved unprecedented levels of speech perception skill 4 to 7 yr after cochlear implantation. Use of an updated speech processor, such as SPEAK, contributed significantly to improved speech perception skills, even in children who were initially fitted with an earlier strategy, such as M-PEAK. In addition, the audiologist who programs the cochlear implant makes an important contribution to the child’s successful outcome with the device. A well-fitted map, as evidenced by a wide dynamic range and optimal growth of loudness characteristics, contributed substantially to the child’s ability to hear speech. Finally, the classroom communication mode used in the child’s school affects speech perception outcome. Children whose educational program emphasized dependence on speech and audition for communication were better able to use the information provided by the implant to understand speech. A variety of speech perception skills were assessed in this study of prelingually deaf 8 to 9 year olds after 4 to 7 years of using a cochlear implant: perception of specific features of vowels, consonants and suprasegmentals, perception of words in a closed set of choices, perception of words and sentences in an open set format, and the amount of enhancement provided to lipreading when audition is added. A wide range of speech perception ability was observed, with better skills seen in children with a wellprogrammed, up-to-date speech processor. Children who had used the SPEAK (as opposed to the MSP) processor the longest and had a greater number of active electrodes in their map with a wide dynamic range and those who could reliably order increases in loudness with increased stimulus intensity achieved the highest speech perception scores. After controlling for these implant characteristics, as well as other contributing factors, most of the remaining variance in speech perception outcome was due to oral classroom communication mode, with the best perceivers having received more auditory and speech emphasis in their educational program since receiving a cochlear implant.