Speech perception performance of children with a cochlear implant compared to that of children with conventional hearing aids. II. Results of prelingually deaf children.

In a previous paper, a method was introduced to transform the results obtained by children with a cochlear implant (CI) on a battery of speech perception tests into an overall value, the "equivalent hearing loss" value. This was achieved by matching the speech perception test scores with those of a reference group of children with conventional hearing aids and hearing loss ranging from 50 to 130 dB hearing level (HL). The equivalent hearing loss values of 16 prelingually deaf children with a CI were plotted as a function of time. There was considerable spread in the rate of progress made by the children in terms of the equivalent hearing loss values. The variables studied, age at onset of deafness/duration of deafness (in the present study, these two factors were indistinguishable) and the communication mode used at the children's school, accounted for 64% of the variance in speech perception performance. A plateau in the performance of the better performers was found which seemed to be caused by the level of hearing (the aided thresholds) with the CI.