The vestibular duct, also known as the scala vestibuli, is a fluid-filled chamber within the cochlea of the inner ear. It is one of the three chambers of the cochlea, alongside the cochlear duct and the scala tympani. The vestibular duct is responsible for conducting sound vibrations that enter the cochlea through the oval window. It is lined with specialized sensory cells called hair cells, which detect the vibrations and convert them into electrical signals that can be interpreted by the brain. The vestibular duct plays a crucial role in the process of hearing and contributes to our sense of balance and spatial orientation.