My late 2011 MacBook Pro has started making this weird noise at random times today. It has done this twice (EDIT: three times, it just happened again), and the second time I recorded it with my phone. The fan on these things is in the middle near the screen hinge. Yet, the sound itself seems to be coming from the left side where the charging port and USB ports are. A restart, sometimes a hard reboot, makes the sound go away. But shutting the sound up isn't fixing the problem, especially if it's just going to come back again. Any ideas? Here is the video, might want to turn the volume up a little, my Nexus 4 has a very focused mic apparently.