Final answer:
The cochlea is a fluid-filled, coiled tube in the inner ear that converts sound vibrations into nerve impulses, with the cochlear duct housing the organ of Corti where hair cells transduce mechanical vibrations into electrical signals for the brain to interpret as sound.
Step-by-step explanation:
The cochlea is an essential part of the human inner ear involved in hearing. It is a coiled, fluid-filled tube that transforms mechanical sound vibrations and positional information into nerve impulses. These impulses are then sent to the brain for processing. The cochlea contains the cochlear duct, also called the scala media, which is the space that hosts the organ of Corti. This organ is filled with hair cells, known as mechanoreceptors, that react to the vibrations caused by sound waves. Surrounding the cochlear duct are two other chambers, the scala vestibuli and scala tympani, which together with the cochlear duct form a triple-chambered tube.
The mechanics of hearing begin when sound travels through the outer ear to the eardrum, causing it to vibrate. These vibrations are then amplified by the middle ear and transmitted to the inner ear via the oval window. This movement sets off a cascade of pressure waves within the perilymph fluid of the cochlea. The waves stimulate the basilar membrane, causing the hair cells in the organ of Corti to bend and convert these mechanical vibrations into electrical signals. These signals travel along the auditory nerve to the brain where they are interpreted as sound. The vestibuli on either side of the cochlear duct and the organ of Corti are key elements in this complex process of hearing.
Muscles in the middle ear also play a protective role by reducing the force of very intense sounds before they reach the cochlea, as well as dampening the sound of one's own voice to prevent self-induced hearing damage.