Final answer:
Adjacent cilia on a hair cell are joined by tip links, which are protein fibers that play a vital role in the hearing process by causing the hair cells to depolarize and initiate nerve impulses.
Step-by-step explanation:
Adjacent cilia on a hair cell in the organ of Corti are joined together by tip links. These protein fibers are crucial in the mechanism of hearing as they tether adjacent stereocilia, ensuring that they bend together in response to sound vibrations. When these stereocilia bend towards the tallest member of their array, the tension in the tip links increases, which in turn opens ion channels in the hair cell membrane. This process results in the depolarization of the hair cell membrane, leading to the initiation of nerve impulses that are then transmitted to the brain.