Final answer:
The inner hair cells in the organ of Corti, which number about 3,500 and are lined up in a single row, are responsible for our sense of hearing by transducing sound vibrations into electrical signals that travel to the brain.
Step-by-step explanation:
The hair cells responsible for our sense of hearing are the inner hair cells located within the spiral organ (organ of Corti). These hair cells line up in a single row and number about 3,500. They have short stereocilia that do not attach to the overlying tectorial membrane but instead extend into small dimples on the membrane's lower surface.
The mechanoreception of these stereocilia, when bent by the vibrations due to sound waves, leads to the opening of ion channels, resulting in membrane depolarization and signal transmission to the cochlear nerve. This stimulus then travels to the brain for auditory processing.
The outer hair cells, numbering about 12,000, are arranged in multiple rows and their role is to fine tune sound waves rather than the direct reception of sound, which is the role of the inner hair cells.