Impact of coiling on cochlear mechanical response: a finite element modeling study

Finite element (FE) modeling can provide valuable insight into the passive mechanical behavior of the human cochlea. Cochlear geometry is commonly simplified as a straight tube in FE models, which may ignore important mechanical and anatomical information. Here, three-dimensional FE models of both coiled and uncoiled cochlear geometries were developed to evaluate the influence of cochlear coiling on basilar membrane (BM) mechanics. Acoustic stimulation was simulated at the oval window (OW) and BM displacement was captured across the human hearing frequency range. Optimization results revealed that reproducing the tonotopic response required distinctive effective Young's modulus distributions for the two geometries: 45-2 MPa, from base to apex, for the uncoiled model; and 67-3 MPa, from base to apex, for the coiled model. Additionally, differences in the magnitude of vibration were observed in the low-frequency range, indicating altered mechanical behavior between models. Findings demonstrated that coiling influences acoustic-structure interaction and mechanical loading along the BM. Therefore, coiling is not a negligible geometric feature and should be incorporated into cochlear models to improve biomechanical understanding and predictive accuracy.