Geometric features of the inner ear important for fluid volume-velocity calculations. (A) Four surfaces (the OW, RW, and two entrances into the SCs from the vestibule) for which volume velocity is calculated in this study (see Fig. 10) are shown, with the middle-ear structure masked for better visualization. (B) A simplified 2-D conceptual diagram of the cochlea with a semicircular canal shows how the x direction of the 3-D diagram relates to the orientation of the scalae fluid chambers in the hook region and a center dehiscence on the SSC. The 2-D diagram was drawn to show the relationship between the orientation of the scalae fluid chambers in the hook region, the x direction, and the normal direction to the dehiscence surface for a center dehiscence, but is not intended to accurately convey the location of a center dehiscence and the y direction as they appear in the 3-D diagram.