Final answer:
The stapes pushes the fluid into the cochlea, creating pressure waves that stimulate hair cells to create electrical signals interpreted as sound by the brain.
Step-by-step explanation:
The motion of the stapes pushes the fluid into the cochlea. When sound waves travel along the auditory canal, they strike the tympanic membrane (eardrum), causing it to vibrate. These vibrations are then transmitted through the hammer (malleus) to the anvil (incus) and finally to the stapes. It is the stapes that presses into the oval window of the cochlea. This action creates pressure waves in the cochlear fluid, stimulating the hair cells, which are anchored to the tectorial membrane. When these hair cells bend, they release neurotransmitters that ultimately lead to the creation of electrical signals that the brain interprets as sound.