Final answer:
When the basilar membrane vibrates at 100Hz, 800Hz, and 5000Hz, this indicates that the sound includes low, mid, and high-pitched tones, activating different hair cells along the length of the cochlea due to the place theory of pitch perception.
Step-by-step explanation:
If the basilar membrane is vibrating intensely at frequencies of 100Hz, 800Hz, and 5000Hz, this means that a sound is being heard with components at low, middle, and high frequencies. The hair cells located on the membrane respond to these specific frequencies, indicating that the perceived sound will have a mix of bass (low pitch), mid-range, and treble (high pitch) tones. Due to the place theory of pitch perception, we know that lower frequencies such as 100Hz stimulate the hair cells at the apex of the cochlea, while higher frequencies like 5000Hz affect the base of the cochlea near the oval window. As the basilar membrane vibrates in response to these frequencies, different hair cells along its length are activated, allowing the cochlea to distinguish between the varying pitches of the composite sound.