Exercisers beware! While personal music players (any device connecting headphones to a source of music) are an awesome way to make cardio more enjoyable, they will also increase your chances of hearing loss and/or chronic tinnitus (ringing in the ears) by a whopping 80%. Two studies done recently, one over a 24-year period, have shown a dramatic increase in hearing deterioration between 2001 - 2008 when PMP's became immensely popular. The obviously solution is to turn down the volume. In the process of making yourself healthier, please do not overlook this important risk factor to your quality of life down the road.