• Background
  • Instructions
  • Illustration
  • Quiz


The stapes of the middle ear asserts pressure on the oval window. This pressure from the stapes causes a wave in the fluid (perilymph) of the middle canal in the inner ear. This pressure wave in the perilymph causes a traveling wave to move down the length of the basilar membrane. Traveling wave here simply means that the wave moves from the base to the apex of the basilar membrane.

In this activity, the cochlea will be unwound and only some of the structures are shown to make it easier to follow how the basilar membrane and cochlea function to transduce sounds. You can speed up and slow down the traveling wave to better understand how the sound pressure at the oval window travels alongt the basilar membrane.


Full Screen Mode

To see the illustration in full screen, which is recommended, press the Full Screen button, which appears at the top of the page.

Illustration Tab


On the Illustration tab, you can adjust these parameters:

Play the Sound: check to start the animation and uncheck to stop the animation.
What Parts of the Ear to Show: Select what part of the ear you wish to examine: the Cochlea, or just the Basilar Membrane.
Speed of Traveling Wave: adjust the rate that the pressure wave travels down the basilar membrane.
Frequency (Hz): adjust to see how the cochlea and basilar membrane respond to different frequencies.
Amplitude: make the sound more or less intense.


Pressing this button restores the settings to their default values and allows you to adjust speed and relative size. It also resets the counter before you can indicate if you have the objects arriving at the same time.