Unless there’s a serious medical condition, most hearing loss occur slowly. It’s part of aging process. You might not notice it in one day, but as you age, your hearing gradually declines. This condition is called presbycusis. Doctors do not know why presbycusis happens, but it seems to run in families. Another cause is the ear infection otitis media, which can lead to long-term hearing loss if it is not treated.
There’s one more cause that is medication. “Ototoxic” medicines damage the inner ear, sometimes permanently. Some antibiotics are ototoxic. Even aspirin at some dosages can cause problems, but they are temporary. Check with your doctor if you notice a problem while taking a medication. But age related hearing loss usually happens slowly. If you’re over 65, have your hearing checked regularly.
Source: National Institute on Aging