Methods and apparatus for performing interferometric measurements on ear tissue within a person's ear, wherein the measurements are performed as a function of pressure within the ear canal. Measurements may be performed at a plurality of pressures, including pressures greater than, and less than, atmospheric pressure. Using an apparatus in accordance with the invention, methods are provided for characterizing a tympanic membrane, as well as a biofilm adjacent to the tympanic membrane, and an effusion in the middle ear. The tympanic membrane may be characterized as to geometrical features and mobility. Characterizations provided by the apparatus serve to diagnose ear pathology.
