Background: The Thiel embalming method offers lifelike tissue preservation, yet its suitability for biomechanical studies remains debated. Methods: Here, we investigated two human temporal bones, one Thiel-fixed and one fresh-frozen, using dynamic synchrotron-based X-ray imaging under acoustic stimulation. Findings: Both specimens exhibited a linear response at the umbo, but the Thiel-fixed specimen displayed discontinuity after the incudo-malleolar joint, suggesting ossicular chain stiffening. Our findings align well with previous studies indicating potential tissue degradation induced by Thiel-embalming. Interpretation: These observations question the use of Thiel-fixed human specimens for biomechanical measurements on the middle ear, especially using dynamic synchrotron-based X-ray imaging. They emphasize the need for further assessment of the impact of Thiel-embalming methods on tissue mechanics.