SPEECH-PERCEPTION PERFORMANCE OF CHILDREN WITH A COCHLEAR IMPLANT COMPARED TO THAT OF CHILDREN WITH CONVENTIONAL HEARING-AIDS .1. THE EQUIVALENT HEARING-LOSS CONCEPT

A new measure has been developed to quantify the speech perception per formance of children with a cochlear implant (CI). The method summariz es the speech perception scores obtained on a battery of tests that ra nges from very basal tasks up to open speech recognition. The overall performance of a child with a CI on the test battery at a certain time during follow-up is matched to that of a reference group of severely and profoundly hearing-impaired children with conventional hearing aid s. This matching procedure results in the expression of the speech per ception scores of a child with a CI as an ''equivalent hearing loss'' value. The equivalent hearing loss concept deals adequately with floor and ceiling effects which inevitably occur when a battery with such a large range of tests is used. To illustrate this, application of the procedure to three children with a CI showed that before implantation, while they were using conventional hearing aids, the equivalent heari ng loss was above 120 dB hearing level(HL). At 3 years' follow-up the equivalent hearing loss improved to 70 dB HL in the two children with an aetiology of meningitis. This means that these children were perfor ming as well as children in the reference group with a hearing loss of 70 dB HL. The child with congenital deafness showed minor improvement s over time.