Answer:
The answer is the Apex of the cochlea
Explanation:
In the human ear, sound waves cause the stapes to press against the oval window. Vibrations travel up the fluid-filled interior of the cochlea. The basilar membrane that lines the cochlea gets continuously thinner toward the apex of the cochlea and different thicknesses of membrane vibrate in response to different frequencies of sound. Since the membrane in the cochlea is thinner towards the apex, sound waves frequency becomes lower.