ABSTRACT
Objective To study the accuracy of traditional basilar membrane displacement evaluation criteria for evaluating hearing compensation performance of round window-stimulated middle ear implant, so as to provide the theoretical basis for performance evaluation of round window-stimulated middle ear implant. Methods An acoustic microscopic finite element model of cochlea was constructed based on experimental data of the cochlea geometry. Reliability of this model was verified by comparison with experimental measurement values of inner hair cell, outer hair cell, tectorial membrane displacement. Based on this model, the displacement of basilar membrane and the stereocilia shear displacement of inner hair cells under forward stimulation and round-window stimulation were comparatively analyzed. Using the stereocilia shear displacement of inner hair cells as the criterion for sense of sound, the equivalent sound pressure level (SPL) deviation under round-window stimulation was studied when using traditional basilar membrane displacement as evaluation criterion. Results At 5 kHz characteristic frequency of the studied slice of cochlea, under sound pressures with the same amplitude, the displacement of basilar membrane and the stereocilia shear displacement of inner hair cells under round-window stimulation were lower than that under forward stimulation. Conclusions Under forward stimulation, the inner hair cells were more excited and the performance for sense of sound was better than that under round-window stimulation. Concurrently, using the displacement of basilar membrane under forward stimulation as the criterion of hearing compensation performance would overestimate hearing compensation performance of middle ear implant under round-window stimulation; but the deviation was relatively small, which was a relatively reliable evaluation method.