Can people after a certain age not hear some noises?

So my dad just walked into my room and somewhere in one of my drawers is a watch that goes off at about five, well it went off while he was in my room and I asked him if he heard it and he said he couldn't hear anything? I know that certain like pitches of things you can't hear after a certain age or something, but this is just a regular wrist watch with a normal beeping alarm.... My dad just recently turned fifty, so is this normal? Or am I just going crazy and hearing beeping noises? Hahaha.