Cochlea to structures in the brainstem for further processing. The "stapes" (stirrup) ossicle bone of the middle ear transmits vibrations to the "fenestra ovalis" (oval window) on the outside of the cochlea, which vibrates the perilymph in the "vestibular duct" (upper chamber of the cochlea). The ossicles are essential for efficient coupling of sound waves into the cochlea, since the cochlea environment is a fluid–membrane system, and it takes more pressure to move sound through fluid–membrane waves than it does through air; a pressure increase is achieved by the area ratio of the tympanic membrane to the oval window, resulting in
Stirrup jar termed "unpainted" although in fact the viewer sees the first coat. It is not the color unpainted fired terra cotta would have; that would be variegated most likely ranging from red to black depending on the firing parameters and content of the clay. For example, Black Glazed Ware features a single coat of black glaze. Red-figure vases are washed with a black slip on which red figures are painted; black-figure vases, a red wash with black figures. Stirrup jars do not bear human figures; nevertheless, some are quite ornamental, with most of the painting surfaces filled with motifs. The stirrup