Noise can be defined as any unwanted sound that when loud enough, can damage your hearing permanently. Noise can range from a shotgun blast to recreational music that you would listen to at home or in your car. There is a general trade off between the loudness and the length of time exposed to the noise. The louder the sound, the shorter the time you should be around that noise before it causes damage.
Aside from destroying your hearing, noise can be a source of tinnitus, fatigue, annoyance, stress, and can interfere with communication. Tinnitus is often perceived as a high pitched ringing or buzzing that can become constant and permanent.