MANHASSET, NY -- A proof-of-concept prototype microphone implanted in the middle ear promises to partly offset the need for wearing an outer hearing aid.
The device would still require patients to wear a charger behind the ear while sleeping to recharge an implanted battery.
The current prototype of the packaged, middle-ear microphone measures 2.5 x 6.2 mm and weighs 25 mgrams, or less than a thousandth of an ounce.
The package is to be reduced to 2 x 2 mm, according to researchers Darrin J. Young, associate professor of electrical and computer engineering at the University of Utah and USTAR, the Utah Science Technology and Research initiative.
The National Institutes of Health says almost 220,000 people worldwide with profound deafness or severe hearing impairment have received cochlear implants, about one-third of them in the United States, where two-fifths of the recipients are children.
A microphone and related electronics worn outside the head raises reliability issues, prevents patients from swimming and creates social stigma.
The system developed by Young implants all the external components. Sound moves through the ear canal to the eardrum, which vibrates as it does normally. An attached accelerometer sensor detects the vibration at the umbo part of the ear and thru processor converts them into electrical signals that are sent to the electrodes in the cochlea.
“Everything is the same as a conventional cochlear implant, except we use an implantable microphone that uses the vibration of the bone,” Young explained.
Young conducted the study with Mark Zurcher and Wen Ko, who are his former electrical engineering colleagues at Case Western Reserve University in Cleveland, and with ear-nose-throat physicians Maroun Semaan and Cliff Megerian of University Hospitals Case Medical Center.
The study was funded by the National Institutes of Health (NIH-DC-006850).
The device has been successfully tested in the ear canals of four cadavers.
Tests in people are about three years away, according to Young.
The paper of the research study is published in IEEE's journal Transactions on Biomedical Engineering