What does the middle ear do in relation to impedance?

The middle ear plays a crucial role in the transmission of sound from the outer ear to the inner ear, particularly through its function of equalizing impedance. The primary task of the middle ear is to efficiently transfer sound waves from the air (in the outer ear) to the fluid-filled inner ear. Air has a much lower impedance compared to the fluid in the inner ear, which can create a significant mismatch that results in sound energy loss.

By equalizing the impedance between the air and the liquid, the middle ear increases the efficiency of sound transmission. It does this using the ossicles (the malleus, incus, and stapes), which amplify the sound vibrations that come from the eardrum. This amplification effectively bridges the impedance gap between the two environments, allowing more sound energy to be transferred into the inner ear, and ultimately improving hearing sensitivity, especially for high-frequency sounds. Thus, by addressing the impedance mismatch, the middle ear enables better sound conduction and enhances overall auditory function.