Why do we hear a sound when paper tears?

Ever wondered why we hear what we hear when we tear a paper? Why did it have to make a sound?

Dumbstruck right? Me too. I had never given it a thought until I read in a friend's blog how a little child asked her that question. And it left me thinking why I never questioned it. We take so many things for granted in this world. We are in such a never ending race that we hardly stop to ponder.

Anyways, back to the question..

We think of sound as something we "hear". Something that makes noise. School taught me that Sound is produced when there are vibrations in the air. Remember the 'U' shaped tuning fork experiment?

So, to answer the question, based on the research I did, it so happens that when you tear a paper, you are breaking the bonds between the atoms that comprise the paper. Now I would expect that if you are able to read this, then you would know what an atom is. So lets continue. When the bonds are broken, it releases some amount of energy into the surroundings in the form of vibrations. The molecules in the surrounding medium, which in this case is the air, are disturbed by the vibrations and they begin to move in a wave like pattern creating low pressure and high pressure areas. Aaaaaand then they hit your ear drums. Which in turn creates more vibrations that are converted into electrical signals and your brain interprets them as Sound. Ta da!

Miraculous, isn't it?


So why doesn't movement of hands in the air produce any sound, you ask? Wait until next Wednesday :P Just kidding. No physics next time.