Effect of electromagnetic middle-ear implant simulating sites on the stapes spatial motion: A finite element analysis

The electromagnetic middle-ear implant (MEI) is a new type of hearing device for addressing sensorineural and mixed hearing loss. The hearing compensation effect of the MEI varies depending on the transducer stimulation sites. This paper investigates the impact of transducer stimulation sites on MEI performance by analyzing stapes spatial motion. Firstly, we constructed a human-ear finite element model based on micro-CT scanning and inverse molding techniques. This model was validated by comparing its predictions of stapes spatial motion and cochlear response with experimental data. Then, stimulation force was applied at four common sites: umbo, incus body, incus long process and stapes to simulate the electromagnetic transducer. Results show that at low and middle frequencies, stapes-stimulating and incus-long-process-stimulating produce similar spatial motion to normal hearing; at high frequencies, incus-body-stimulating produces similar results to normal hearing. The equivalent sound pressure level generated by the stapes piston motion is less sensitive to the stimulation direction than that deduced by the stapes rocking motion. Simulation results of stapes spatial motion can effectively evaluate the performance of electromagnetic middle ear implants in treating sensorineural hearing loss at different stimulation sites. The displacement maps show that at low and medium frequencies, stapes-stimulating and incus-long-process-stimulating produce similar spatial motion to normal hearing. At high frequencies, incus-body-stimulating produces similar results to normal hearing. The equivalent sound pressure level (ESPL) generated by the piston motion of the stapes is less sensitive to the stimulation direction than the rocking motion ESPL. Among all stimulation sites, the stapes is the best. image