Herein, a two degree-of-freedom model of the reconstructed middle ear using shape memory prosthesis is investigated near the primary resonance for various prosthesis types. The polynomial model of shape memory alloy is used to characterise the properties of the prosthesis. To solve the differential equations of middle ear motion, the multiple time scales method is applied. The first- and second-order approximations of the primary resonance curves are compared with each other and verified through numerical simulations. The obtained analytical solutions studied for the stiff and flexible prosthesis reveal various accuracies depending on the prosthesis stiffness. The second-order approximation of the multiple scales method reveals unstable harmonic vibrations near the primary resonance zone, but are not found in the first-order approximation.