How are sounds of different frequency differentiated in the cochlea?

Answer 1

The cochlea is a conical organ wrapped on itself to form a spiral, not unlike the shell of a snail.
Any vibration that travels through it will move in until it reaches a point where the dimension of the cochlea is related to the frequency, where it will resonate and stimulate sensory cells that are located there (and only those, save for the harmonics).

Answer 2

The cochlea is snai shell shaped and it contains the organ of corti. The organ of corti is the actual organ we hear with. Sounds from the ear drum vibrate the 3 tiny bones the ear ossicles and they in turn vibrate the Oval window. The oval window is a membrane opening into the bony cochlea. The different frequencies of sound will resonate at different places in that snail shell. Nearest the oval window are where the lowest freqs. vibrate and the tip of the shail shell is where the high freqs. vibrate. Where the sounds vibrate is where the hair cells will be activiated and they in turn send nerve impulses to the brain. It is the brain that interprets those nerve impulses as sound.

Answer 3

By the rate in which it is caused to vibrate.