Why do people have three ear bones?

Hearing is something most of us take for granted, which is reasonable. Unless we put them under severe strain, our ears normally function well and don't require any upkeep. However, not everyone is content to accept our ears for what they are. Sunil Puria, a Stanford researcher, observed that reptiles and birds only have two ear bones, but mammals have three, and no one knows why. Puria claims that we hear in a variety of ways. The first is apparent, with sound passing through our ears, but we also hear things when vibrations from our voice chords move through the bones in our skulls.

When you talk, you truly hear your own voice differently than everyone else. This explains why we dislike hearing our own voices reflected back to us. Puria's best idea explains why humans have a third ear bone by referring to a unique condition known as semicircular canal dehiscence. This condition can produce a reduction in tissue in the ear canal, causing patients to hear distracting sounds they wouldn't typically hear, such as their own heartbeat. Puria speculates that the third ear bone is intended to mitigate these impacts, but he feels that much more research is required.