SALT LAKE CITY—Every year, hearing aids get smaller and less conspicuous. Indeed, several manufacturers are now marketing devices that they categorize as IIEs, invisible-in-the-ear hearing aids.
Now, it appears, cochlear implants may also be on the path to invisibility. In current systems, the microphone, speech processor, and radio transmitter coil must be worn outside the head because they are too large to be implanted. Even if users don’t mind that their system is conspicuous, they still face hassles related to the exterior placement of key components.
However, the recent development of a tiny prototype microphone that can be implanted in the middle ear may prove a key step toward making all-in-the-ear cochlear implants a reality. The inventors of the microphone, which is about the size of the eraser on a pencil, report that it has been successfully tested in the ear canals of four cadavers. Their study was published online in the Institute of Electrical and Electronics Engineers journal Transactions on Biomedical Engineering.
The senior author of the study is Darrin J. Young, an associate professor of electrical and computer engineering at the University of Utah and USTAR, the Utah Science Technology and Research initiative. Young, who moved the Utah in 2009, conducted the study with Mark Zurcher and Wen Ko, his former electrical engineering colleagues at Case Western Reserve University in Cleveland, and with the ear-nose-throat physicians Maroun Semaan and Cliff Megerian of University Hospitals Case Medical Center.
In an interview with the public relations office at the University of Utah, Young pointed to the promise of the tiny new microphone to make the systems more user-friendly than the present ones with their external parts.
“Imagine a child wearing a microphone behind the ear. It causes problems for a lot of activities. Swimming is the main issue. And it’s not convenient to wear these things if they have to wear a helmet.
“For adults,” he said, “it’s social perception. Wearing this thing indicates you are somewhat handicapped, and that actually prevents quite a percentage of candidates from getting the implant. They worry about the negative image.”
Young also raised the issue of reliability with external parts. “If you have wires connected from the microphone to the coil, those wires can break.”
The current prototype of the packaged, middle-ear microphone is 2.5-by-6.2 millimeters, roughly one-tenth by one-quarter inch, and weighs less than a thousandth of an ounce. Young wants to reduce the package to 2-by-2 millimeters and improve its ability to detect quieter, low-pitched sounds. He estimates that tests in people are about three years away.
To hear a recording of the start of Beethoven’s Ninth Symphony through the new microphone implanted in a cadaver’s middle-ear, go to this link and look near the top of the page.