Which of the following best describes the primary function of the round window?

• A. Converts mechanical energy into neural signals
• B. Regulates endolymph production
• C. Absorbs the wave's energy and dissipates it
• D. Amplifies the traveling wave on the basilar membrane

Answer: (C)

The primary function of the round window is to serve as a pressure release valve in the cochlea. When the stapes pushes on the oval window, the fluid inside the cochlea needs somewhere to move, and the round window membrane bulges outward to absorb and dissipate that energy. This prevents pressure from building up and allows the traveling wave on the basilar membrane to propagate smoothly, enabling the auditory system to transduce mechanical vibrations into neural signals without distortion or damage.

It’s not about converting mechanical energy to neural signals—that happens when hair cells in the organ of Corti bend and their mechanotransduction channels open. It doesn’t regulate endolymph production—that is handled by the stria vascularis and related fluids. It also doesn’t amplify the traveling wave—the amplification comes from cochlear mechanics, including outer hair cell motility and the stiffness gradient of the basilar membrane.