The helicotrema (from Greek: ἕλιξ [helix] meaning coil and τρη̂μα [trēma] meaning hole) is the inner upper part in the structure of the inner ear (cochlear labyrinth).
The structure of the human inner ear, which also includes the structures of the vestibular apparatus and is directly connected with the cochlear labyrinth through Sacculus and Utriculus by endolymph moving inside them and the cochlear duct. The cochlear duct itself with endolymph flows in the organ of Corti, inside of which stereocilia (hair cells) are located on the surface of the basilar membrane.
It is in the hair cells that the process of mechanotransduction occurs, when the mechanical energy of the sound wave is recognized by the hair cells (about 20-25 thousand in each cochlear duct) due to vibrations, converted into a nerve impulse and sent to the brain along the path of the hearing analyzer.
The hair cells itself is not directly related to the helicotrema, since the helicotrema does not pass endolymph through itself, but the perilymph at the very top of cochlear labyrinth, stereocilia (hair cells) near this area (helicotrema) best detect low frequency sounds.