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Case No. 6: Wearing Headphones
The problem is not the headphones, per se; it's that most of us are unaware of how we're actually using them, found a study at the U.K.'s Bristol University. When volunteers wore standard iPod earbuds in loud places—subways and on the street, for example—their listening level was found to be so high that they were at risk for permanent hearing damage over time. (Note: Ears don't always ring when seriously assaulted.)

Try instead: Wear noise-canceling headphones (they sample background noise and cleverly "cancel it out" by feeding an inverse signal). People who used these in lieu of earbuds set their listening levels up to 4 decibels lower—which translates to about a 40 percent decrease in the risk of hearing loss.