My Mac is making an odd noise every couple of minutes Total Mac OS noob here, after spending a lifetime on Windows I have my first Mac.

Every couple minutes I hear an odd sound (playing through the speakers), it sounds like two beeps in quick succession, with a puddle-like noise in the background.

It doesn't seem to be anything listed under Sound Effects in the control panel.

What does this sound mean, and do I have to do anything?
This sounds like the sound Skype makes for a Contact Available notification.