This is just a cool little attention-to-detail things. Did you know that Dictation for Mountain Lion (Mac OS X 10.8) temporarily turns off the MacBook fan in order to hear your speech better?
As you may know, internal microphones pick up a lot of outside noise. One of those noises is the whirring fans of a MacBook. The noise could possibly interfere with the software’s ability to hear you correctly.
We’re sure that Apple went through quite a bit of testing, and found that this was the best way to go about it. It’s just kind of a neat little factoid.