Tiny circular holes in upper left corner of Macbook Pro

Just wondering, does anyone know what function the very tiny holes arranged in a circular pattern (located in the upper-left corner of the keyboard on aluminum unibody Macbook Pros) serve? I tried covering them to see if it was the keyboard light sensor, but that didn't seem to work. I checked around online, too, but couldn't find anything about them. Thanks!

It's the microphone.

The light sensor is built into the screen surround.

I didn't even think of that lol - thanks for the help, mrplow! I'm still new to the site, but you guys are awesome!