I wondered that too. I'm almost 66 and had no problem.
I should mention, in 1965 when the army was trying to draft me, a hearing test was part of the physical. You put on headphones and you were to raise a hand when you could hear something, right or left. I kept both hands raised the whole time to the consternation of the test administrator. I told him I could hear a low level hum cycling throughout and he gave up.