Numerical study on the effect of the floating mass transducer on middle ear sound transmission

To overcome some inherent problems in conventional hearingaids, such as low gain at high frequencies, discomfort, and acousticfeedback, floating mass type for middle ear implant system are currentlyunder development. The floating mass transducer (FMT) is the most importantcomponent of these devices. For the purpose of investigating the effect ofthe FMT to middle ear sound transmission, a middle ear finite element modelwith FMT clamped was constructed. This model was built based on a completeset of computerized tomography section images of a healthy volunteer's leftear by reverse engineering technology. The validity of this model wasconfirmed by comparing the motion of the tympanic membrane and stapesfootplate obtained by this model with published experimental measurements onhuman temporal bones. The result shows that FMT produces mass loading effectprominently at high frequencies, the force required to drive the incus tothe equivalent of 100\,dB SPL is about 8.9 dynes, and placing the clamp pointof the FMT close to the incudostapedial joint enhances the driving effect.