The Tiny Lens That Could Stop Hearing Loss from Earbuds

Since the rise of the iPod, earbud headphones have become unavoidable—as have concerns that they are causing widespread hearing loss. So Stephen Ambrose invented a microscopic lens that absorbs the vibrations of sound while still allowing full audio signals to pass through to the ears.

By Mike Ryan
Ambrose Diaphonic Ear Lens

Ambrose Diaphonic Ear Lens

Asius Technologies, LLC

May 17, 2011 1:00 PM Text Size: A . A . A
You hear it all the time—your earbuds will cause hearing loss. And while it'd be nice to shrug this off as the same old conventional wisdom that everything fun is bad for us, it happens to be true: Prolonged use can in fact lead to hearing loss. A clever new invention being unveiled Friday may help keep your earbuds and your hearing—and your audio quality—intact, without forcing you to return to an era of Footloose-style Walkman headphones.

The problem with all headphones, simply, is that sound creates pressure. And the very design of earbuds, which fit into your ear canal to block out all other sounds, makes the situation only worse. When the ear is completely sealed off, that sound pressure has nowhere to go except straight to the tympanic membrane (the eardrum). The pressure causes unnatural motion of the membrane that, over a long period of exposure, leads to ear fatigue and hearing loss. Some earbud models now feature holes cut into the earpiece in an effort to allow the pressure to escape, but they yield mixed results and definite losses in audio quality.

This was not acceptable to Stephen Ambrose, the president of Asius Technologies. Better in-ear tech has been his decades-long quest: As a 13-year-old musician in 1965, he noticed that he couldn't hear his voice onstage; by 1976, when he was 24, he invented the first professional in-ear monitor. His newest invention, intended to solve the earbud hearing loss problem without giving up good sound, is called the Ambrose Diaphonic Ear Lens. Made out of a medical-grade polymer that's just 2.5 microns thick, the lens can be retrofitted inside the rubber tip of an earbud. "Sealing a speaker in the ear is beating up an eardrum," Ambrose says. "So what we did was we let it pick on someone else. We put another eardrum in there that is more compliant."

Ambrose's lens works by distinguishing between two types of pressure: sound pressure and static pressure. You can experience sound pressure in any surrounding, like, say, in your car, when listening to music. Static pressure is created when the ear canal is sealed off; it is not dependent at all on music. The Diaphonic Ear Lens mimics the motion of the speaker inside the earbuds, and by doing so can catch and negate only the static pressure—Ambrose compares it to a sail capturing the wind. This allows the sound pressure to reach your ear as music, allowing you to hear the full range of sound in a song without the static pressure banging on your eardrum.

The audio quality stacks up nicely, too: Last week, PM got a test listen in Manhattan. First, Ambrose offered up a pair of unmodified, Skullcandy earbuds and queued up Peter Gabriel's "In Your Eyes" on his iPhone. And it sounded, well, okay. Ambrose then attached two of his lenses inside the rubber tips of those same Skullcandy earpieces—and the difference was striking.

The key was a drastic reduction of the occlusion effect: Cover up your ears and say something—the occlusion effect is that booming sound of your voice in your head. Instead of hearing bass as it should sound, you're left with an unnatural booming sound in your head. By contrast, that full and encompassing experience of Ambrose's lenses was a direct result of the reduction of the occlusion effect by absorbing the static pressure trapped in the ear canal. "We can do more to improve the way a speaker sounds by treating the eardrum than they can do with hundreds and hundreds of dollars of technology invested into making the speaker," Ambrose says.

The lens is actually an outgrowth of Ambrose's original (and even more ambitious) idea to combat this issue: the Ambrose Diaphonic Ear Lines Inflatable, which is basically a small airbag that, after insertion of the earbud, expands even further into the ear and conforms to the ear canal as it expands. PM tested this prototype, too. And though having something inflated inside your ear canal makes the listening experience feel more like a trip to an ear specialist, Ambrose's inflatable was the closest we've ever experienced to having music delivered intravenously. It completely blocks out extraneous noise; you can barely hear yourself talk. However, the inflatable device would cost about $650—a bit pricey for people who simply want to listen to "The Safety Dance" in peace on their commute—and so an idea for the lens was born. It should cost more like $20 and could be fit into existing earbud styles. Ambrose says he plans to begin selling the lenses in a few weeks, first in the replaceable rubber ear tips for earbuds, and eventually as full headphone sets with the lenses built in.

These systems aren't just for rocking out on your way to work, either. The National Science Foundation funds Ambrose's research because of its promise for broader biomedical uses—improving sound quality for hearing aids, for example. While it's great to have a nice sounding speaker in your ear, Ambrose says reducing stress on the eardrum is the true game changer. "People do deserve to have their hearing protected and [have] a greater fidelity," Ambrose says. "And there's no reason it has to be expensive."

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