The footplate of the stapes helps with hearing. The stapes bone notifies the oval window when movement occurs. The stapes footplate proceeds into the oval window, sending the round window membrane out, allowing for the fluid in the cochlea to move, which leads to the cochlear inner hair cells' movement, and finally, hearing. When, or if, the round window is fixed or missing, which occasionally happens, the stapes footplate pushes incompressible fluid into the rigid walls of the cochlea. Since it wouldn't move, it would lead to a loss of hearing.