The average ear (Auris media) is the middle part of the ear and consists of the tympanic membrane, the Eustachio tube and the oval and round windows. In the tympanic cavity are contained the oscillations of the middle ear. Timpan has the role of transforming the sounds collected by the external ear into vibrations, which are sent to the three oscillators (hammer, anvil and stair). In turn, they send the vibrations to the inner ear.
So the cochlea is not part of the average ear