How you can impair your hearing?

I don't think so. But obviously it's much safer than blasting music in your ears.

hearing is something you have a ear drum in your ear witch every time you hear something

Depends on if you mean hearing in a space shuttle, or hearing out in real "space." Sound travels through air, so if you were out in real "space," sound waves would not travel since there is no air...

How is hearing on earth different from hearing in space?

Depends on the cause of hearing loss. If the loss is conductive - ie. caused by a problem with the ear canal, ear drum, bones behind the ear or middle ear cavity, there is a good chance that it could...