Though people differ in their sensitivity to loud noise, generally speaking, noise may damage your hearing if you have to shout over it to be heard, if it hurts your ears, makes them ring, or if you are slightly deaf for a period of time after exposure to the noise.
Most otologists agree that continual exposure to a noise that is 85 decibels or louder in intensity is dangerous.
Click the link for a full-color chart that displays examples of various noises and their decibel levels.
When a noise is too loud is begins to kill the nerve endings in the inner ear. The more you are exposed, the more nerve endings are destroyed, and the worse your hearing will be.
NERVE DAMAGE IS PERMANENT!
Once it is damaged your hearing can not be restored. Additionally, noise exposure can lead to temporary and sometimes permanent ringing in the ears (tinnitus). Though the nerve endings can not be replaced, there are options for hearing rehabilitation through amplification.
When you will be exposed to noises over 85 dB (decibels) you should wear hearing protection. OSHA requires hearing conservation programs for noisy work environments.
If you have either symptoms of hearing loss or ringing in the ears, you should seek evaluation by an otolaryngologist, who can diagnose and classify hearing loss and provide appropriate treatment options.