Imagine this situation - you are in a group of people, all talking together in a social setting. But you can't contribute to the conversation because you can't really make out properly what people are saying.
Your hearing WILL be damaged by exposure to loud sound. Both level and duration of exposure are factors. By far the most common source of loud sound is the pair of earpieces connected to your personal stereo. Going to clubs where loud music is played night after night is also a risk. Factory noise can be a problem, but the factory where you work should offer you ear protection. Make sure you use it.
Hearing damage, by the way, is permanent. Tiny hair cells in the inner ear are destroyed and they never grow back.
As a sound engineer or recording engineer, your ears are vital to your career. But you risk damaging your hearing every day you work. Possibly the worst situation is when you are a trainee engineer working in the studio with someone who is already partially deaf. They might want to work at levels that are painful for you. But you are not in a position to ask them to turn it down. Not if you want to stay in the room.
The moral is to expose yourself to loud sound for as short a duration as possible. If you work all day with high levels in the studio, then don't listen to any more loud music at home.
To close, here is one of the standard jokes of the recording industry...
What do you call a recording engineer who over the course of many years in the studio has become totally deaf?