The ear is divided into three parts - the outer ear, middle ear, and inner ear.
Sound waves travel through the ear canal and to the eardrum. The sound waves cause the eardrum to vibrate and pass through the middle ear bones, which creates movement in the fluid of the inner ear. This snail-shaped structure, called the cochlear, contains thousands of hair cells. The movement of the hair cells sends electric signals from the inner ear up the auditory nerve to the brain.
The brain then interprets these electrical signals as sound.
The American Speech-Language-Hearing Association (ASHA) describes how we hear in greater detail.
Raising Deaf Kids describes how we hear, which includes: