3D imaging could help improve hearing aids

A new imaging technique out of MIT could result in hearing aids--and earphones and earplugs--that fit and function better.

Elizabeth Armstrong Moore
Elizabeth Armstrong Moore is based in Portland, Oregon, and has written for Wired, The Christian Science Monitor, and public radio. Her semi-obscure hobbies include climbing, billiards, board games that take up a lot of space, and piano.
Elizabeth Armstrong Moore
2 min read
A new 3D scanning technique could help construct better-fitting hearing aids and headphones. MIT

If you're one of the 17 percent of American adults who reportedly suffer from some type of hearing loss, listen up: hearing aids--and earphones--may be about to enter a new generation of superior fit and functionality, thanks to molds based on a 3D imaging technique instead of plaster.

Time was, getting fitted for a hearing aid took an hour in a chair with an audiologist, who would fill a patient's ear canals with a silicone substance that hardened into a mold from which the aid would be constructed. The molds are only so detailed, which means the fits are only so tight.

Researchers at the Massachusetts Institute of Technology have taken a new approach with a stretchy, balloon-like membrane inserted into the ear canal and then inflated to take on the canal's detailed shape. They then fill that membrane with a fluorescent dye that a tiny fiber-optic camera inside the balloon can scan in a matter of seconds.

The new scanner developed at MIT captured this image of an ear canal. Federico Frigerio/MIT

Because the camera captures 3D images so fast, it is also able to measure how the contours of the ear canal change with pressure, or with motion such as chewing and talking, measurements that could even further improve the fit of hearing aids, as well as earphones used with MP3 players and earplugs for, say, military personnel.

"A lot of people with hearing aids are likely walking around with hearing aids that don't fit, because they don't know what they're supposed to feel like," says Douglas Hart, a professor of mechanical engineering at MIT who patented the system in January and has founded a company to bring it to market.

The team is now building a handheld version of the device that they plan to study, comparing the fit of hearing aids built with the new scanner to that of traditional aids.