The modern dilemma: pedestrians and personal music players

10 July 2017
Train arriving in Britomart train station.

The tragic deaths of pedestrians in road or rail accidents while distracted by listening to music through headphones have been highlighted in research from the University of Auckland.

Research from the University’s School of Population Health has shown that pedestrians who listen to music through earphones are significantly impaired in their ability to localise warning signals above the noise of traffic and trains around them.

The World Health Organisation estimates that around 270,000 pedestrians are killed annually worldwide, which equates to around 22 percent of road deaths. On New Zealand roads, 25 pedestrian deaths and 862 injuries were reported in 2015, and almost 400 pedestrians were killed and 10,000 more injured between 2005 and 2015 (Ministry of Transport, 2016).

In the case of train accidents during 2015 alone, there were 22 occurrences involving pedestrians at level crossings (including cyclists) and 597 occurrences due to person-on-track. From 2005 to the end of May 2016, there were 20 reported deaths and seven injuries at pedestrian level crossings.

Recently completed work by Masters of Audiology student Alicia Tay, undertaken with Associate Professor Grant Searchfield at the University’s Eisdell Moore Centre, used a simulated train station environment to show that participants were unable to correctly hear warning car horns when surrounded by the noise of trains and traffic played to them.

The main problem does not appear to be the ability to detect the sound, but rather to identify where it is coming from.  Tightly fitting in-ear earphones and headphones covering the ears produced greater problems locating the direction of sound and thus greater risk of miscalculating the direction of approaching traffic or trains, compared to earphones sitting in the outside of the ear.

The study tested the hearing of 20 people by sitting them individually at the centre of a circle of 12 speakers that played the sounds of trains and nearby traffic noise recorded at Henderson Station. Participants had to detect and localise a car horn coming from one of the 12 speakers in a random order. The sounds were played to the people in three different conditions: with a personal music player (the study used an iPhone 6) and three different styles of headphones (Circumaural or over-the-ear headphones, in-ear earphones, and earbuds) with and without music, and listening naturally without earphones or music.

People tested while wearing headphones that cover the outside of the ear and listening to music failed on more occasions to hear the sounds than those wearing earbud headphones or in-ear earphones.  The researchers believe that it was the disruption of cues normally provided by the shape of the outside of the ear, as well as preventing the ears working together as normal that was responsible for the problems.

“The outer ear, what is scientifically known as the pinna, provides information useful to identify sounds, as do both ears working together as a set. Taking out one earphone to reduce risk of accidents may not be as safe as people think, as that further disrupts our ability to tell where sounds are coming from,” explains Associate Professor Searchfield.

The study also took into account that the average pedestrian would likely increase their music volume in response to greater traffic noise, further hindering their hearing ability.

Now they are researching how earphones and music players can be designed to reduce this risk.

Associate Professor Searchfield says, “I became aware of the high number of deaths in which listening to music over headphones was implicated and clearly there was a need to identify what contributed to these accidents, and if we could design solutions, to reduce the risks and save lives”.

Research shortly to be undertaken will be looking at the effects of using a new generation of headphones that do not block external sound.  The research group hopes to develop methods to enable headphones to automatically switch transparency depending on the environment.

“The cost of rail and pedestrian deaths are great as it impacts not only the victims but the victims’ families, the witnesses and train and car drivers on a psychological level,” Associate Professor Searchfield says.


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