Speech perception performance of children with a cochlear implant compared to that of children with conventional hearing aids. I. The "equivalent hearing loss" concept.

A new measure has been developed to quantify the speech perception performance of children with a cochlear implant (CI). The method summarizes the speech perception scores obtained on a battery of tests that ranges 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 aids. This matching procedure results in the expression of the speech perception 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 hearing 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 performing as well as children in the reference group with a hearing loss of 70 dB HL. The child with congenital deafness showed minor improvements over time.