Thresholds of hearing as a function of age and sex for screened, or 'otologically normal', persons have been standardised (ISO 7029) on the basis of a study by Robinson and Sutton (1978). For purposes such as the evaluation of hearing loss due to noise exposure in industrial populations, it is not generally realistic to compare the hearing thresholds to an age-matched 'otologically normal' baseline, since the difference will include adventitious hearing loss as well as the noise-related components. This paper presents typical data for an unscreened population, in a companion form to ISO 7029. The results are derived from a critical analysis of published material and are shown to converge closely to ISO 7029 at the extremity of the distributions. Striking uniformity in the form of the distributions is revealed among apparently discordant data from different studies, showing that the adventitious hearing loss, or so-called 'pathological overlay', is essentially equivalent to accelerated ageing.