What's too loud: Federal OSHA standards say the ear can tolerate eight hours a day of 90-decibel sound (the sound of a well-tuned power mower), four hours at 95 decibels, two hours at 100 decibels, and so on. Many audiologists say those times should be cut in half.

Ear pain begins at 125 decibels (ambulance siren), permanent damage with short exposure at 140 decibels (gunshot), and death of hearing tissue at 180 decibels (rocket launch).

Signs of trouble: Even temporary ringing in the ears, ear pain or difficulty understanding conversation may mean hearing loss.

What to do: For concerns about environmental noise at work or school, ask to have the noise level tested or adjusted, or seek access to earplugs.

Get tested by an audiologist for hearing loss. Consider using earplugs whenever you're around loud sounds, such as some indoor concerts, athletic games, lawn mowers or snowblowers.

Earplugs may reduce high-frequency sounds by 10 decibels; for better protection or if you are a musician, ask an audiologist or your school about earplugs for musicians.

To learn more: For online information, go to the Mayo Clinic at www.startribune.com/a1786and the Occupational Safety and Health Administration at www.startribune.com/a1787