Incidence, prevalence and etiology of hearing impairment in children in the county of Västerbotten, Sweden.

During the period 1964-83, 63,463 children were born in the county of Västerbotten, Sweden. Of these children, 160 had a hearing impairment greater than or equal to 30 dB HL mean hearing loss for the frequencies 0.5, 1.0 and 2.0 kHz in the better-hearing ear. The mean annual incidence of hearing impairment was 2.5 per 1,000 and the prevalence was 2.6 per 1,000. Hereditary factors were present in 46% and no etiology could be established in 34% of the cases. The incidence of hearing impairment was greater than has been presented in studies from other areas in Europe.