Look around these days, and you'll see earphone cords dangling around many necks. The advent of newer, more affordable digital music players (DMPs) and smartphones has lots of us toting mini personalized jukeboxes in our pockets, a steady soundtrack accompanying our commutes, workouts, and idle moments in waiting rooms.

These devices have become so ubiquitous, of course people wonder if there are risks in all this noise. Examining three common speculations, we find some truth and some fiction.

Can listening to these devices cause hearing loss?

The risk to your ears from DMPs and smartphone music players is not that different from the risk from older or outmoded personal music players. People have slid on headphones or plugged in ear buds for years, whether to listen to records or radios, cassettes or CDs, and hearing loss has actually declined in recent decades.

One troubling thing about the newer, tinier, personal music players is the frequency with which we use them. Since MP3 players and smartphone can hold hundreds and hundreds of songs, and most slip right into your pocket, some people are hooked up to their tunes almost constantly.

Exposing our ears to a steady stream of high-decibel noise can lead to noise-induced hearing loss. This type of hearing deficit can happen if you're listening to music ringing in at about 85 decibels for about 8 hours, but some varieties of players have the volume capacity to reach over 100 decibels. And those buds that nestle snugly into your ear can boost the decibels even higher.

Experts recommend keeping your volume at a safe, reasonable level (if someone has to shout for you to hear them, it's too loud!). Some suggest a 60/60 rule: listen to your device at 60% of its volume capacity for no more than 60 minutes a day.

Can MP3 players interfere with pacemakers?

It all started with a curious teen with aspirations to become a doctor someday. Wondering over the effect of DMPs on pacemakers, he set about conducting an experiment. He discovered signs of electrical interference when he held a DMP close to the chest of men outfitted with pacemakers. His findings were published in the medical journal, Heart Rhythm, and the story made a lot of noise among consumers. Could music make hearts skip a beat?

Most research has documented that headphones can interfere with a pacemaker when they are too close together. The American Heart Association recommends keeping headphones (both earbuds and clip-on types of headphones) at least 3 cm away from a pacemaker.

Are iPods lightning rods?

One day a man jogged along while tunes from his iPod motivated him onward, even as a thunderstorm rumbled around him. A bolt of lightning to a nearby tree interrupted his workout, sending the man flying 8 feet from the tree. Running in a thunderstorm seems to have been the first of this man's bad decisions for the day. Besides receiving second degree burns to his chest and leg, the man also suffered burns that matched the outline of his iPod earphones and cord, a fractured jaw, and some hearing loss due to two blown eardrums.

The man's wounds have healed, but the public's worry lingered: could headphones and mp3 players, cell phones, or other small metallic or electronic devises increase the risk and severity of lightning strikes? While the earphone-cord-shaped burns would seem to suggest some correlation, the iPod may have only helped along a natural occurrence. Burst eardrums are common side effects of a lightning strike, and there actually is no scientific evidence to show that wearing or holding metal devices will turn a person into a lightning rod.

In this unlucky man's case, the lightning hit the tree and side-flashed over to him, and the earphone cord and sweat conducted the current up toward his head. That would account for the muscle contractions that fractured his jaw. The lesson here? Take shelter indoors when a thunderstorm starts, no matter how inspiring your playlist is!

Amy Toffelmire