Eardrum. Artwork of the eardrum, or tympanic membrane, as seen from the outer ear. The eardrum is a thin membrane that separates the outer and middle ear. It is slightly conical in shape, with the umbo (round projection, centre) at the apex of the cone. It transmits sounds, as vibrations, from the air to the bones (ossicles) of the middle ear. The malleus (hammer), one of the ossicles, attaches to the eardrum at the manubrium of malleus (projection from top to bottom).