In profoundly deaf people who are candidates for cochlear implants, the hair cells don't work for a variety of reasons, including birth defects, side effects of drugs, exposure to excessively loud sounds or infection by certain viruses.
In a cochlear implant, the microphone, signal processor and transmitter coil worn outside the head send signals to the internal receiver-stimulator, which is implanted in bone under the skin and sends the signals to the electrodes implanted in the cochlea to stimulate auditory nerves. The ear canal, eardrum and hearing bones are bypassed.
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. But at the umbo, a sensor known as an accelerometer is attached to detect the vibration. The sensor also is attached to a chip, and together they serve as a microphone that picks up the sound vibrations and converts them into electrical signals sent to the electrodes in the cochlea.
The device still would require patients to wear a charger behind the ear while sleeping at night to recharge an implanted battery. Young says he expects the battery would last one to several days between charging.
Young says the microphone also might be part of an implanted hearing aid that could replace conventional hearing aids for a certain class of patients who have degraded hearing bones unable to adequately convey sounds from conventional hearing aids.
Testing the Microphone in Cadavers
Conventional microphones include a membrane or diaphragm that moves and generates an electrical signal change in response to sound. But they require a hole through which sound must enter a hole that would get clogged by growing tissue if implanted. So Young's middle-ear microph
|Contact: Lee Siegel|
University of Utah