The Gesundheit Bot

So I have a co-worker who is constantly sneezing... and thought it would be funny to build a little robot that would say "gesundheit" when she sneezed. Is there a way to build this, make it voice activated, so that it only responds to her sneezes? I know its a strange idea, but any thoughts would be appreciated.

How about configuring voice activation on any PC in the area, and defining the sound of a sneeze as the command that plays back a sound file?