Potential Solution for Listener's Fatigue Found

For years, musicians and other people working with in-ear headphones have been aware of the dangers of listener's fatigue, a condition in which the ear drum becomes unresponsive to sounds of a certain volume. Now, experts believe they have a solution to this issue.

This is tremendous progress in this field, since scientists didn't even know the cause of this condition until very recently. But researchers behind the new study have not only identified its root cause, but also a potential cure, that may help countless professionals.

Experts now believe that listener's fatigue sets in after prolonged exposure to loud volumes of music, played through in-ear headphones. The high volume forces the eardrum to oscillate by up to a few micrometers, which is not right.

Generally, when hearing sounds in nature, the eardrum moves around by only a few nanometers, which are billionths of a meter. According to researchers at the Longmont, Colorado-based company Asius Technologies, the much more significant movement is responsible for the fatigue.

The discovery was presented on May 14 in London, during the 130th convention of the Audio Engineering Society. The work was conducted by experts Stephen Ambrose, Robert Schulein and Samuel Gido.

Sealing an in-ear speaker in the ear – as many modern headphones do – is a very bad thing to do, the team explains. The large volume increases pressure in the canal, forcing the eardrum to work overtime.

However, by applying just a few minor modifications to the tip of the in-ear headset, this effect can be turned from a dangerous to a positive one. The new earphones were designed using both computational and physical models.

“We tried for years to turn down the volume but still experienced audio fatigue, even at the lowest levels we could get by with on stage,” explains Ambrose, who has been conducting work in this field for more than 35 years.

“The fatigue couldn't simply be ‘fixed in the [audio] mix' because it now appears to be a physiological phenomenon. It wasn't a problem with electronics, but rather mechanics,” he explains.

The expert and his team created what they refer to as the synthetic “sacrificial” membrane technology. What this involves is placing a small membrane on the tip of the in-ear headphones, to act like a second eardrum, and take over excessive pressure and vibrations.

In tests conducted with such a model, the eardrum returned to exhibiting nanometer-long oscillations, whereas the second membrane took the vast majority of shocks. The sounds themselves were heard a lot clearer as a result too, the US National Science Foundation (NSF) reports.






Video Description: New research suggests a cause, and potential solution for the listener fatigue caused by in-ear headphones.
Video Credit: NSF / Steve McNally and Lisa Raffensperger