July 2020 ENGINEERING.com
A popular, though unscientific, online publisher’s viral article on Apple’s AirPods causing hearing loss made us think “Where have we heard this before?” It was 4 years ago that Stephen Ambrose and his ADEL (Ambrose Diaphonic Ear Lens) in-ear sound monitors were being built for the express purpose of reducing the risk of hearing loss from ear buds, the ubiquitous in-ear speakers.
Catching up with Stephen, we find his crusade to stop one health threat (hearing loss) is stymied by another one much more serious: COVID-19. The man who has miraculously restored AC/DC’s Brian Johnson’s hearing with in-ear sound monitors, has had his research put on hold by the pandemic. With no one performing, gone is Stephen’s quest to complete his research.
What follows is our original 2016 article:
As a kid, Stephen Ambrose hid in his closet so that he could listen to music and sing. To escape detection, he had in his ear a tiny speaker that was held in place first with bubble gum, then later with Silly Putty. His classical music–loving dad did not approve of his music, which included the likes of Johnny Cash, who back in the 1960s played his “devil’s music” next door—the same place where, at the age of 13, Ambrose would land his first recording session. The homemade earpiece was to become the forerunner of the in-ear monitor that Ambrose went onto invent. Musicians now use in-ear devices to hear how they are sounding to their audiences—or to get instructions from the crew, sound engineers and so on. Before in-ear monitors existed, musicians relied on onstage speakers that faced them, feeding back to them the sound the audience was hearing, not just their own voices and instruments. In-ear monitors also took care of another problem: delivering instructions or directions to performers. Stevie Wonder, blind since shortly after birth, would fall off the stage. His crew would yell to him at full volume over the concert sound system,“Get back, get back!”
Ambrose was to become a musician and an inventor. In the 1970s, he would fit Stevie Wonder with a pair of in-ear monitors, which involved filling both the singer’s ears with an impression material. Wonder was said to have exclaimed, “Oh my God, I'm blind!” Although Wonder had been blind from shortly after his birth, he "saw" life with his ears, which were suddenly sealed shut with the impression material used to make the custom ear moulds for his first in-ear monitors. Once the monitors were finished and installed, Wonder could "see" from all the microphones on stage. Ambrose and Wonder then set off on the first world tour that used the in-ear monitors throughout.
Even if you have not heard of Ambrose’s work, you may have seen it. Beyoncé wore an in-ear monitor when she performed during halftime at the 2016 Super Bowl.
Beyoncé at the 2016 Super Bowl with Stephen's invention in her ear—an in-ear monitor
Little did Ambrose know that his invention would actually lead to hearing loss. Once sealed in the ear, the miniature speaker acts like a piston, creating pneumatic pressures in what is now effectively a closed cylinder. Relatively low sounds (as low as 60dB) are transformed into high pressures that can prematurely trigger the acoustic reflex and even create a chemical change in the cochlea, leading to irreversible hearing loss. Ambrose, realising that his invention was leading to hearing loss, quit the music industry. Obtaining grants to study the physiological and medical causes of hearing loss, he atones by setting up Asius Technologies and creating the ADEL(Ambrose Diaphonic Ear Lens) in-ear device, a “safer” approach to in-ear devices.
The Asius ADEL in-ear device,which used Autodesk Fusion 360 in its design
Ambrose has also come up with what he says is a better design for an earbud—one with a “second eardrum” that takes the pounding so that your real eardrum doesn’t have to—or cannot. The ADEL device depends on transcranial conduction, where sound is routed from one ear location to the other, even if one ear is not working at all. We see Paul Stanley of Kiss give Ambrose a thumbs-up after being fitted with the ADEL. Brian Johnson can play again. But these devices are not just for rock stars. At $149, everyone can get in on the act. Users with bad hearing are shown to hear again, with tears in their eyes, as if Ambrose has performed a messianic miracle. Ambrose spent two days during Accelerate 2016, where he was also chosen to provide the keynote address, personally fitting a non-stop procession of attendees, all of whom express visible surprise at how good Ambrose’s earbuds sound.
Asius points to medical literature that shows the ADEL earbuds effectively lower listening volumes and have even been chosen as an alternative to cochlear implants. Ambrose credits the modeling of the earbuds to Autodesk Fusion. “Fusion has changed my life,” he said, providing an unabashed endorsement of Autodesk’s design and manufacturing platform. That and a Formlabs printer (“the best desktop 3D printer ever!”) have provided him with untold speed and flexibility. A usable part can be made on premise, rather than having to be sent out for.