If you are planning to go for a walk, leave the headphones at home. A new study has found that the number of people who are seriosuly injured or killed while walking and wearing headphones has increased significantly in recent years.

According to US researchers, many people wear headphones for handheld devices, such as iPods, when out walking. They decided to gather information on the number of deaths and injuries among such pedestrians. They looked at all cases in the US between 2004 and 2011. The use of mobile phones while walking was not included.

The study found that during the 2004/05 period, there were 16 cases of serious injury or death among pedestrians wearing headphones. By 2010/11, this figure had tripled, rising to almost 50.

Those affected were most likely to be teenagers or young adults and two in three were male. The vast majority of accidents occured in urban areas.

Almost three in four of the incidents were fatal and in at least one in four incidents, witnesses mentioned that horns or sirens were used before the accident occured.

According to the researchers, the most likely cause of such accidents is distraction and/or sensory deprivation. In other words, the victim is unable to hear any sounds outside of what they are listening to on their headphones.

They described this type of distraction as 'inattentional blindness' and noted that the use of headphones is on the increase.

"The risks posed by the use of these devices by drivers are well documented. But little is known about the association between headphone use and pedestrian injury," they added.

Details of these findings are published in the journal, Injury Prevention.