It’s a familiar refrain from parents of teens: You try to talk to them but they just don’t listen.

A new study suggests that the problem might be something else: Maybe they just can’t hear you.

Researchers analyzing data on 12- to 19-year-olds from a nationwide health survey found that about 20 percent of American teens have lost at least a little of their hearing, and the number has increased dramatically in recent years.

The researchers don’t point any fingers to what has caused this trend, but anyone who is paying attention should be able to figure out that it might have something to do with the brightly colored wires that are coming out of their ears.

Digital music players, like the iPod, and their characteristic earbud headphones have become standard equipment for kids from the upper elementary school grades right through high school.

It’s easy to see why. While young people of another generation had to go up to their rooms and put a record on the turntable to make the world go away, today’s kids can do it while they are riding a skateboard, waiting for the school bus or studying for a test.

But there is mounting evidence that the cost for this convenience is a lifelong disability. The authors of this study don’t connect the dots, but a 2010 Australian study linked personal listening devices with 70 percent of childhood hearing loss.

This doesn’t mean that kids shouldn’t listen to their MP3 players, but parents should be ready to pay closer attention to their teens’ use of them. Popular programs like iTunes allow users to limit maximum volumes, and parents should get familiar with those controls.

This study is a call to action. If parents want to protect their kids’ hearing, they should listen to it.