The comparison to (early) detection of tooth decay, which is common practice, is an obvious one - why is this not the case with hearing impairment?
It is of course critically important to detect hearing damage early. The traditional audiogram is aimed at a specific facet of hearing, namely detecting sound. It does not determine the extent to which tones (frequencies) can be distinguished from each other and/or if speech can be understood. Damage is therefore often only noticed once it is already too late.
Oto-acoustic Emissions (OAEs)is preferred technology for early detection as it identifies hearing damage at a very early stage; even before the person in question becomes aware of it or is bothered by it, and long before an audiogram shows any deterioration.