Serious injuries to pedestrians listening to headphones have more than tripled in six years, according to new research from the University of Maryland School of Medicine and the University of Maryland Medical Center in Baltimore. In many cases, the cars or trains are sounding horns that the pedestrians cannot hear, leading to fatalities in nearly three-quarters of crashes.

Researchers reviewed 116 accident cases from 2004 to 2011 in which injured pedestrians were documented to be using headphones. Seventy-percent of the accidents resulted in death to the pedestrian. More than two-thirds of victims were male and under the age of 30.

More than half of the moving vehicles involved in the accidents were trains and nearly a third of the vehicles reported sounding some type of warning horn prior to the crash. The increased incidence of accidents over the years closely corresponds to documented rising popularity of gadgets with headphones.