A tectorial (roof) membrane is held in place by a hinge-like mechanism on the side of the Organ of Corti

and floats above the hair cells. As the basilar and tectorial membranes move up and down with the traveling wave, the hinge mechanism causes the tectorial membrane to move laterally over the hair cells.

Does the tectorial membrane vibrate?

The more rigid a tectorial membrane is, the higher the frequency at which it can vibrate. Thus, the flexible end of the membrane—which should respond to low-frequency vibration— is found near the hair cells that transmit low frequencies, and the rigid end near hair cells that transmit high ones.

What does motion of the tectorial membrane do?

Moreover, in combination with the contractile force of outer hair cells, it is proposed that inertial motion of the tectorial membrane provides the necessary conditions to allow positive feedback of mechanical energy into the cochlear partition, thereby amplifying and tuning the cochlear response.