Email Print Share

"Different Drum" -- The Discovery Files

The Discovery Files
Audio Play Audio
The Discovery Files podcast is available through iTunes or you can add the RSS feed to your podcast receiver. You can also access the series via AudioNow® by calling 641-552-8180 on any telephone.

Engineers investigating "listener fatigue"--the discomfort and pain some people experience while using in-ear headphones, hearing aids, and other devices that seal the ear canal from external sound--have found not only what they believe is the cause, but also a potential solution.

Credit: NSF/Karson Productions

Audio Transcript:

(Sound effect: hip hop scratch) Nipping It in the Bud.

I'm Bob Karson with the discovery files -- new advances in science and engineering from the National Science Foundation.

(Sound effect: hard rock) If you're listening to this with earbuds you could experience "listener fatigue." And it has little to do with me, the subject matter or this music. It's your ears just doing their job. Engineers at Colorado's Asius Technologies have the cause and the cure for this condition.

Their research deals with systems that seal the ear canal such as in-ear headphones or hearing aids. They initially found these systems create a highly magnified sound pressure level. And what amounts to a physiological 'catch-22'. You see, your ear has a built-in acoustic reflex that's triggered by high sound pressure levels. Sound gets dampened to protect your inner ear, but that in turn causes you to turn the device up louder. The more you pump it up, the more you subject your eardrum to excessive shaking.

Once the team understood the way the process works, they set out to develop a system that would break the cycle. Their solution: build a "second" eardrum a synthetic membrane attached to the tip of any in-ear device to take the brunt of the pounding. Eardrum protected no acoustic reflex and lower volumes sound louder.

The accurate, non-fatiguing sound provided by this new technology can be retrofitted on existing devices. It could mean a safer, richer sound for those wearing hearing aids (Sound effect: loud music) and less need to "crank it up" (Sound effect: loud music abruptly cuts) for the rest of us.

"The Discovery Files" covers projects funded by the government's National Science Foundation. Federally sponsored research -- brought to you, by you! Learn more at or on our podcast.

General Restrictions:
Images and other media in the National Science Foundation Multimedia Gallery are available for use in print and electronic material by NSF employees, members of the media, university staff, teachers and the general public. All media in the gallery are intended for personal, educational and nonprofit/non-commercial use only.

Images credited to the National Science Foundation, a federal agency, are in the public domain. The images were created by employees of the United States Government as part of their official duties or prepared by contractors as "works for hire" for NSF. You may freely use NSF-credited images and, at your discretion, credit NSF with a "Courtesy: National Science Foundation" notation. Additional information about general usage can be found in Conditions.

MP3 icon
NSF podcasts are in mp3 format for easy download to desktop and laptops, as well as mobile devices capable of playing them.