Final answer:
Sound waves cause the tympanic membrane to vibrate, leading to movement of the ossicles and pressure on the oval window, which creates waves in the cochlear fluid and results in the perception of sound.
Step-by-step explanation:
Sound waves cause the tympanic membrane to vibrate, pushing the ossicles up against the oval window.
When sound waves enter the ear, they travel up the auditory canal and make the eardrum, or tympanic membrane, vibrate. These vibrations are then transferred through the three small bones in the middle ear, known as the malleus, incus, and stapes (collectively called the ossicles). Finally, the stapes, which is the last of the three bones, presses into the oval window of the cochlea, which leads to the formation of pressure waves in the cochlear fluid. These pressure waves stimulate hair cells in the cochlea, which are then translated into nerve impulses that the brain perceives as sound.