What part of the ear converts sound waves to nerve signals?
The cochlea in the inner ear.
The ear is divided into three regions: the outer ear, the middle ear, and the inner ear.
While the first two sections collect and transmit sound as waves/vibrations, the inner ear, comprising the cochlea and semicircular canals is responsible for converting that physical energy into electrical energy (nerve impulses).
This is done in the cochlea, a snail-shell shaped organ that is lined with fine, delicate cilia with different frequencies.
The vibration of these cilia according to the received vibration from the middle ear is converted into nerve impulses which are transmitted by the auditory nerve (also called the cochlear nerve) to the brain for interpretation as sound.