Effect of Driver Mass Loading on Bone Conduction Transfer in an Implantable Bone Conduction Transducer

This paper focuses on transducers, which are the most important components of bone conduction implants. To improve vibration magnitude, we develop a coil vibration transducer in which the driver mass loading is reduced by about 3.25-fold compared to magnet vibration transducers. We use finite element analysis to derive and implement the maximum Lorentz force and frequency characteristics. We compare the effect of driver mass loading on the vibration magnitude to that of an older transducer. The new transducer vibrates about 4.4-fold more strongly. To compare force magnitude between the two transducers, output force is measured using an artificial mastoid. The force imparted by the new transducer is higher than that of the older transducer only below 1.4 kHz, and tends to be lower at high frequencies. Nevertheless, the improved force in the low-frequency region will improve conductive hearing loss.