## 5 Discussion and Conclusions  
This study focused on measuring the dynamic properties of the RWM in the human ear using sound stimulation and an LDV to analyse the response characteristics. The experiment identified several resonances in the RWM vibrations. Overall, the results were consistent with previous studies reported in the literature, though some minor differences  
Figure 7: The initial stages of the inner-ear simulation with a visible traveling pressure wave: (**a**)—3.75 \(\times\) 10\({}^{-6}\) s; (**b**)—1.5 \(\times\) 10\({}^{-5}\) s; (**c**)—3.0 \(\times\) 10\({}^{-5}\) s.  
were observed. These variations may be attributed to differences in experimental setups, such as the mass of reflective tapes used for laser vibrometry measurements or the origin and storage conditions of the temporal bones. Additionally, the recorded resonance amplitudes varied depending on whether the artificial ear canal was open or closed, indicating that sound waves within the canal can significantly interfere with those reflected in a closed canal setup. A significant novel approach introduced in this research was the use of the frequency response function ratio, mutually relating the RWM and stapes footplate vibrations. The RWM typically displayed about twice the vibration amplitude as the stapes, with the most significant amplification occurring around 1 to 2 kHz. This FRF ratio provides new insights into cochlear dynamics, offering a potential tool for comparing different cochlear models, including healthy and pathological conditions. In terms of numerical modelling, a simplified computational fluid dynamics model of the cochlea was developed, which approximates the basilar membrane's dynamic behaviour. This model was proposed to reduce computational time while capturing essential fluid flow dynamics. The initial simulations showed satisfactory agreement with the experimental results, particularly for frequencies of 1 and 2 kHz, despite the use of linear models without full coupling. The final conclusions can be listed as follows:  
* RWM vibrations: The experimental results indicate that the RWM exhibits characteristic resonances, with noticeable differences in amplitude based on whether the ear canal is open or closed. The FRF ratio between the RWM and stapes footplate is a promising metric for assessing cochlear function. * Cochlear modelling: The simplified 3D model of the cochlea demonstrated good alignment with the experimental findings, validating its potential for future research. Despite its simplicity, the model captured key aspects of fluid flow and vibration transmission within the cochlea. * Applications: The FRF ratio and numerical models developed in this study provide valuable tools for investigating cochlear mechanics, which could be useful in clinical settings, particularly for evaluating prosthetic devices or conditions like otosclerosis. Conceptualization, R.R., M.S. and R.Z. ; methodology, R.R. ; software, S.T. ; validation, R.Z., G.Z. and R.R. ; formal analysis, R.Z. ; investigation, S.T., J.L., M.S., A.K. and R.R. ; resources, R.R. and M.S. ; data curation, G.Z. ; writing--original draft preparation, R.Z. ; writing--review and editing, J.L., R.Z., S.T. and R.R. ; visualization, S.T. ; supervision, R.R. and J.L. ; project administration, R.Z. and G.Z. ; funding acquisition, R.Z. and G.Z. All authors have read and agreed to the published version of the manuscript. The research was financed in the framework of project no. 2022/45/N/ST8/02447, funded by the National Science Centre, Poland. Not applicable. The numerical data used to support the findings of this study are available from the corresponding author upon request. Special thanks to [PERSON] from Warsaw University of Technology, Faculty of Power and Aeronautical Engineering, Institute of Aeronautical Engineering and Applied Mechanics, Department of Strength of Materials and Structures.