Is the relation of social class to change in hearing threshold levels from childhood to middle age explained by noise, smoking, and drinking behaviour?

Recent work shows that variation in adult hearing function is related both to social class of origin and current social class. This study examines how much of this relationship after adjustment for childhood hearing impairment is explicable by occupational noise, current smoking, and alcohol consumption. A cohort of 9023 persons born in the UK during one week in 1958 was followed periodically, and hearing threshold levels (HTLs) were measured at 1 kHz and 4 kHz at age 45 years. Most (71% and 68%, at 1 kHz and 4 kHz respectively) of the relation to social class of origin of adult HTLs remains after adjustment for these other factors. For the relation to current social class, corresponding values are 64% and 44% (though varying by gender). The magnitude of social class effect is comparable to that of occupational noise. Susceptibility to hearing impairment is likely to be appreciably determined in early childhood.