Estimates for the prevalence of self-reported hearing disability and measured hearing impairment as a function of age in the adult population of Great Britain (GB) are reported from two 2-stage surveys. The main study was conducted in Cardiff, Glasgow, Nottingham and Southampton, with rigorous audiological assessment at the second stage. A supplementary study used a sample representative of GB with simplified domiciliary audiological assessments. In the main study, neither stage showed any gross bias arising from the particular cities chosen; the estimates from the first stage are free of bias arising from non-response. The estimates from the second stage are relatively free of bias arising from non-attendance. For the present purposes, defining a 'significant' level of hearing impairment as at least 25 dBHL averaged over the frequencies 0.5, 1, 2, 4 kHz, 16% of the adult population (17-80 years) have a bilateral, and about one in four a unilateral or bilateral, hearing impairment. About 10% of the adult population (aged 17+) report bilateral hearing difficulty in a quiet environment.