TECHNOLOGY FOR CHANGE

Say Again? Good News for Hearing Loss

Rebecca Kutzer-Rice | Date: 05-24-10 | Comments

Existing methods of fitting hearing aids are costly, inconvenient and ineffective. Researchers from MIT have invented a new imaging technology that could lead to better hearing devices.

Currently, only one in five Americans who could benefit from a hearing aid actually wears one. Douglas Hart, an MIT professor of mechanical engineering, has patented a new imaging technology that could lead to better-fitting hearing devices and more widespread usage.

In order to function properly, hearing aids must be custom-fitted to patients� ears. Existing ear measurement methods are lengthy, expensive and uncomfortable. In a process that takes up to an hour, an audiologist fills a patient�s ear canal with a messy silicone gel, which hardens to form an inaccurate mold. This method often leads to a bad fit, which can cause annoying feedback, discomfort and patients choosing not to wear their devices. Says Scott Witt, head of research and development for hearing-aid manufacturer Phonak, �Taking these impressions is still the messiest, least-exact part of the process.� Additionally, traditional hearing aids can come with a thousand-dollar price tag�a cost that many insurance companies do not cover.

Poorly fitting hearing aids are less likely to be worn (source: MIT).

New MIT technology involves taking a 3-D picture of a patient�s ear canal. Unlike the time-consuming practice of molding, 3-D imaging takes only a minute or two. Here, a doctor inserts a thin, dye-filled membrane into a patient�s ear canal. A tiny fiber-optic camera, housed within the membrane, then scans and records the contours of the ear. The camera can also capture changes in the ear�s shape that occur when a patient chews or talks.

Because this imaging process is so much faster and leads to accurate results on the first try�unlike the molding method, which must often be repeated�it is significantly cheaper. Perhaps most importantly, precise measurements lead to better-fitting hearing aids and more frequent use by patients.

Three-dimensional images of the ear canal create more comfortable hearing devices (source: Federico Frigerio).

Unlike other proposed technologies, MIT�s 3-D imaging technique is highly compatible with current manufacturing processes. States Witt: �We could do it right now. The rest of our manufacturing process is set up to receive digital scans.�

While his priority is to improve hearing aids, MIT�s Hart believes that 3-D ear imaging will be useful in many industries. He envisions custom-made earphones benefiting military personnel, workers in noisy environments and listeners of music.

In addition to support by MIT, the project was funded by a grant from The Deshpande Center for Technological Innovation.