The structure in the human ear responsible for hearing is the cochlea. It is a spiral-shaped organ filled with fluid that converts sound waves into electrical signals. These signals are transmitted to the auditory nerve, which sends them to the brain for interpretation. The cochlea contains tiny hair cells that move in response to sound vibrations, leading to the generation of nerve impulses. This intricate mechanism allows us to perceive a wide range of sounds, making the cochlea essential for auditory function.