A sound wave enters the outer ear, then goes through the auditory canal, where it causes vibration in the eardrum. The vibration makes three bones in the middle ear move. The movement causes vibrations that move through the fluid of the cochlea, which is located in the inner ear. The vibrations stimulate small hair cells in the inner ear, which transforms them into electrical impulses the brain interprets as sound.
The eardrum is also known as the tympanic membrane. The three tiny bones in the middle ear are collectively referred to as the ossicles. Their individual names are the malleus, also known as the hammer; the incus, also known as the anvil; and the stapes, also known as the stirrup. The hair cells located in the inner ear each have 100 to 200 cilia at the top. Cilia are sensory organs, and the longest cilia have tectorial membranes at the top, which move back and forth with sound cycles.
Sound travels as a wave through the outer and middle ear before transforming into an electrical impulse. The first area of the brain that receives auditory input is the primary auditory cortex. It contains neurons that interpret sound information from the ears. The primary auditory cortex is surrounded by and connected with the secondary auditory cortex.