A study of the application of a frequency transposition hearing system in children

The aim of this retrospective study was to investigate the use of the frequ ency transposition Transonic FT 40 system in a group of 36 children with pr ofound sensorineural hearing loss. The group comprised 36 children (11 boys , 25 girls) aged between 2.8 and 15.6 years (mean 7.6 years) at fitting of the FT 40 device. At 48 months post-FT 40 fitting, only 11 children (30%) w ere still wearing the device. The children discontinued wearing the FT 40 f or the following reasons: ergonomic (11%); no perceived benefit from the sy stem (11%); cosmetic (17%); and subsequent cochlear implantation (30%). The performance of the long-term FT 40 users was investigated using the follow ing outcome measures: aided soundfield hearing thresholds: closed set speec h tests (the E2L toy test and the Manchester, Picture Test discrimination t est) and a speech intelligibility rating score, The 11 long-term FT 40 user s (three boys, eight girls) were aged from 5.3 to 12.9 years (mean 7.2 year s) at the time of initial fitting of the FT 40 device. At time of fitting, the aided soundfield thresholds with the FT 40 were significantly better at 500 Hz (p<0.04), 1 kHz (p<0.019), 2 kHz (p<0.001) and 4 kHz (p <0.001) com pared to thresholds with conventional hearing aids. Six of 11 children did not show any change in performance on the closed set speech tests and two c hildren had intelligible speech at 48 months' follow-up. A small subgroup o f good performers was identified. These children were younger at age of fit ting (mean 6.2 years compared to a mean of 7.7 years for the remainder of t he group), were predominantly oral communicators and had identified aetiolo gies for their deafness. The present study suggests that there is a small s ubgroup of hearing-impaired children who benefit from frequency transpositi on hearing systems, and future suggested fitting criteria and outcome measu res are listed.