I investigate the function and evolution of the middle ear apparatus in vertebrates. Comparative anatomy is backed up with more recent techniques, such as micro-CT and laser interferometry, in order to visualise the middle ear structures and examine their motion. Measurements are incorporated into models of middle ear function, to establish the hearing ranges and sensitivities of the ears, the results being considered in the light of the ecology of the animals. One main focus has been the function of the extraordinarily enlarged ossicles of some subterranean mammals, apparently used for detection of seismic vibrations by a form of inertial bone conduction. Another focus of my research has been the function of the middle ear of amphibians, which I have shown to be considerably more complicated than has previously been realised, and which may also be used for detection of vibrations other than airborne sound waves.