Which part of the ear amplifies sound before it reaches the inner ear?

The stirrup, also known as the stapes, is a small bone located in the middle ear that plays a crucial role in the amplification of sound. When sound waves enter the ear, they cause the eardrum to vibrate. These vibrations are transmitted to the ossicles, which are three tiny bones in the middle ear: the malleus (hammer), incus (anvil), and stapes (stirrup).

The stapes is connected to the oval window of the cochlea in the inner ear. As it moves, the stirrup amplifies the vibrations coming from the eardrum by acting as a lever. This amplification is essential for the sound waves to be converted into fluid waves in the cochlea, enabling hearing to occur.

The other parts of the ear mentioned, while important, do not function primarily to amplify sound in the same way. The eardrum receives and transmits sound but does not amplify it. The outer ear gathers sound waves and channels them into the ear canal but does not provide amplification. The hammer and the incus are part of the chain that conducts sound to the stirrup, but it is the stirrup that directly amplifies the vibrations before they reach the inner ear.