What is the lining inside the cochlea that helps convert sound waves into electrochemical signals?

The lining inside the cochlea that is integral to converting sound waves into electrochemical signals is the basilar membrane. It functions as a critical component of the cochlea's structure, where sound-induced vibrations lead to displacement of the hair cells located atop it. As sound waves travel through the fluid of the cochlea, they create pressure changes that cause the basilar membrane to vibrate. This vibration is crucial because it stimulates the hair cells, which then transduce the mechanical energy of these vibrations into electrochemical signals sent to the auditory nerve and ultimately to the brain.

The oval window, cochlear duct, and round window serve different functions in the auditory system. The oval window is a membrane-covered opening that receives vibrations from the stapes bone, which transmit sound waves into the cochlea. The cochlear duct, while part of the inner ear structure containing the endolymph and facilitating the sense of hearing, is not the component that directly converts sound into electrical signals. The round window provides a release point for the fluid waves generated in the cochlea, ensuring that movement occurs in the cochlear fluid but it does not play a role in the conversion process.