A micro-drive hearing aid: a novel non-invasive hearing prosthesis actuator
The direct hearing device (DHD) is a new auditory prosthesis that combines conventional hearing aid and middle ear implant technologies into a single device. The DHD is located deep in the ear canal and recreates sounds with mechanical movements of the tympanic membrane. A critical component of the DHD is the microactuator, which must be capable of moving the tympanic membrane at frequencies and magnitudes appropriate for normal hearing, with little distortion. The DHD actuator reported here utilized a voice coil actuator design and was 3.7 mm in diameter. The device has a smoothly varying frequency response and produces a precisely controllable force. The total harmonic distortion between 425 Hz and 10 kHz is below 0.5 % and acoustic noise generation is minimal. The device was tested as a tympanic membrane driver on cadaveric temporal bones where the device was coupled to the umbo of the tympanic membrane. The DHD successfully recreated ossicular chain movements across the frequencies of human hearing while demonstrating controllable magnitude. Moreover, the micro-actuator was validated in a short-term human clinical performance study where sound matching and complex audio waveforms were evaluated by a healthy subject.
KeywordsAuditory implants Auditory prostheses Cadaveric testing Hearing aids Microactuators Temporal bone measurements
The authors wish to thank individuals who donate their bodies and tissues for the advancement of education and research. Ethical approval for the use of human temporal bones was given through the University of California Irvine School of Medicine Willed Body Program. The authors also wish to thank Melinda JD Malley for her technical assistance in device assembly.
Conflict of interest
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