Assessment of expressive vocabulary outcomes in hearing-impaired children with hearing aids: do bilaterally hearing-impaired children catch up?

Objective: To evaluate expressive vocabulary growth in hearing-impaired preschool children wearing hearing aids. Design: Prospective analysis of the outcomes of children included in the 1994 German 'Goettinger Hoer-Sprachregister' (GHR) series, using a repeated-measures paradigm in six- to nine-month intervals (t1-t3). Subjects: Twenty-seven children (aged 2.0-4.4 years) with bilateral sensorineural hearing loss (with averages at frequencies of 0.5, 1, 2 and 4 kHz of > 20 to > 90 dB in the better ear) from the 1994 GHR series. The children were diagnosed at a mean age of 31.4 months (standard deviation (SD) 10.6 months) and fitted with a binaural hearing aid at a mean age of 32.3 months (SD 10.5 months). Nonverbal intelligence was average (five missing data entries). Standardized, age-appropriate picture naming tests (the 'Sprachentwicklungstest fur 2-jahrige Kinder', the Kaufman Assessment Battery for Children subtest vocabulary, and the 'Aktiver Wortschatztest fur drei- bis sechsjahrige Kinder') were carried out at three time points and results compared with data from children with normal hearing. The test raw scores were converted to T scores (mean = 50; SD = 10). Results: On average, the children scored far below the normative population at t1 (mean = 28.9; SD = 11.3) and slowly improved as they got older (at t3, mean = 34.1; SD = 16.1; p = 0.010). Children with mild or moderate hearing loss improved most notably (mean difference t1-t3; p = 0.001), except for one child of deaf parents. Two of the five mildly hearing-impaired children and two of the eleven moderately hearing-impaired children caught up with their normal hearing peers with regards to expressive vocabulary. Such expressive vocabulary achievements were not seen in any children with > 70 dB hearing loss or in six of the eleven children (55 per cent) with a 40-70 dB hearing loss, despite receiving adequate personal amplification. Conclusion: Testing expressive vocabulary size is a useful clinical tool in assessing linguistic lexical outcome.