Weapons fire, ordnance and blast produce extremely high sound pressure over milliseconds. That is not the same hazard as steady machinery noise, and hearing protection rated for continuous noise does not necessarily behave the same way…
Weapons fire, ordnance and blast produce extremely high sound pressure over milliseconds. That is not the same hazard as steady machinery noise, and hearing protection rated for continuous noise does not necessarily behave the same way against it. Damage can occur from limited exposure, which is why a veteran who spent relatively little time near weapons can still have measurable loss.
Flight lines, engine rooms, armour, generators, and aircraft all produce sustained high-level noise across long shifts, often without practical opportunity to remove yourself. The combination of sustained exposure and intermittent impulse events is particularly damaging.
Noise damage accumulates in the cochlea's hair cells and those cells do not regenerate. Early loss sits in the high frequencies, which carry consonant sounds rather than volume - so speech seems audible but unclear, especially in background noise. People typically describe it as others mumbling long before they describe it as deafness, and often years after separation.
A baseline audiogram now is useful whether or not you have symptoms: it documents your current hearing, it gives future tests something to compare against, and if you later claim service connection, contemporaneous records are more persuasive than recollection. Testing costs you an appointment.
Primary regulations and standards referenced above. Where a standard is published commercially it is named in full rather than linked to a copy.