Abstract
Objective: To describe a novel magnet-drive micro hearing aid (MMHA), a 3.5-mm wide device, that fits entirely into the bony canal and drives the tympanic membrane (TM) using a magnet in a noncontact fashion. To test the effectiveness and optimal positioning of the magnet on the TM.
Method: Cadaveric temporal bones were prepared for laser Doppler vibrometry (LDV) of the stapes. MMHA was placed at 1 and 2 mm away from the TM, and the magnets were glued to umbo and lateral process of the malleus. Frequency sweeps between 300 Hz to 12 kHz were performed.
Results: The MMHA showed frequency response from 300 Hz to 12 kHz at loudness levels from 60 to 120 dBA at 10 dBA steps. Placement of magnet on the umbo resulted in higher amplitudes and lower power requirements than placement on the lateral process. The same results were observed when the device was placed at 1-mm distance from the TM.
Conclusion: MMHA is a small completely-in-the-canal hearing aid that drives the TM in a noncontact fashion through a magnet. This novel device has a frequency output wider than air conduction devices. The device’s ability to directly drive the TM enables it to potentially sound more naturally and similar to implantable devices.
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