Deeply affected by the death of a teenager who didn't hear a train coming down the tracks, a pediatrician rounded up similar accidents.

A Maryland teenager died while crossing the railroad tracks. Even though the train blew its whistle, the teen made no move to get out of the way and was run over.

Why did it happen? The teen had headphones on and couldn't hear the train.

Deeply affected by the teen's death, a Maryland pediatrician began searching for reports of similar cases. Using several national databases, he found that serious injuries to pedestrians wearing headphones have more than tripled in the last six years. The typical victim in these accidents is male and under 30.

Headphones are great for shutting out the rest of the world. Sometimes people don't realize just how good a job they do. And there are places where being cut off from the world around you is the worst possible thing to do. Pedestrian crossings are at the top of the list. But more than half the accidents uncovered in the last six years involved trains. Headphones are indeed more powerful than a locomotive.

Looking over case reports of pedestrian injuries or fatalities involving moving vehicles between 2004 and 2011, the doctor and his team found 116 where the victim was using headphones. Seventy percent of these accidents were fatal. More than two-thirds of the victims were male (68 percent) and under the age of 30 (67 percent). Over half of the vehicles involved in the accidents were trains (55 percent), and nearly a third (29 percent) reported sounding a horn prior to the crash.