Final answer:
The cochlea uses the basilar membrane to detect pitch by having different parts of the membrane vibrate in response to specific sound frequencies, with hair cells tuned to these frequencies along its length.
Step-by-step explanation:
The cochlea detects differences in the pitch of sound because different frequencies vibrate different areas along the basilar membrane. The mechanical properties of the basilar membrane change along its length, making it responsive to a wide range of frequencies. High-frequency sounds cause vibrations near the base of the cochlea, while lower frequencies vibrate the apex. This phenomenon is explained by the place theory, which is supported by the orderly arrangement of hair cells on the basilar membrane, varying in sensitivity to different frequencies.
As sound waves travel through the cochlea, they displace the fluid inside, causing the basilar membrane to flex. Hair cells, located on the basilar membrane, are stimulated by these motions, and they are most sensitive to specific frequencies based on their location. This fine-tuned responsiveness allows the cochlea to act similarly to a prism, separating the component frequencies of auditory stimuli.