Longitudinal study of hearing in children: baseline data concerning auditory thresholds, noise exposure, and biological factors.

Serial auditory thresholds are being recorded at six-month intervals from 224 children and youths aged 4--18 years. The data from the first year show girls have lower threshold levels than boys, especially from 12--17 years, and, in both sexes, those aged 12--17 years have lower thresholds than those aged 6--11 years. Median total noise exposure scores tend to be higher in boys than girls, especially after 10 years of age, but these scores are not significantly correlated with auditory thresholds levels. The incidence of exposure to events associated with noise increases markedly in teenage boys and is related to auditory threshold levels. There are no significant associations between auditory thresholds levels and responses to general health questions or attained stature, but there are associations with meatal abnormalities. There is suggestive evidence, particularly in girls, that rapid maturation is associated with lower threshold levels, especially at lower frequencies.