Shhhhhhhh, wait a minute, I can hear them ;-)
[tiny hijack]Near where I live, there are some giant ant colonies with ant-home-mounds 1 1/2 to 2 1/2 feet high and spaced not very far apart. There are so many ants that if you stop while you're hiking on a windless day, you can actually hear them. They sound like a rustling noise. It's a bit eerie.[/tiny hijack]