If you were able to hear frequencies lower than 20Hz, you could hear your muscles moving!

Our senses are amazing things. Although they don't give us a completely accurate picture of the world, they give us just enough information to be able to carry out our lives.

For example, you might know that humans can't ever hear certain sound frequencies. However, that's not such a bad thing. If you could hear frequencies under 20 hertz, you would actually be able to hear your muscles move!