OS X Dictation: A full list of commands
Apple’s OS X Dictation functionality, new in Mountain Lion, is really quite good. Yes, it’s limited and isn’t a threat to professional speech recognition packages, like Nuance’s Dragon Dictate, but OS X Dictation is free and very, very easy to set up and use.
First of all, OS X Dictation in Mountain Lion isn’t active by default. To turn Dictation on (or off):
• In System Preferences > Dictation & Speech > Dictation tab > click the “On” radio button
That said, Apple’s first iteration of OS X Dictation recognizes 60 commands. The vast majority are quite simple (i.e. saying “question mark” types a “?”), though there are some somewhat more complex commands, like saying “Roman numeral” will type the spoken number as a Roman Numeral.
And, for what it’s worth, Nuance recently began shipping Dragon Dictate 3, which is the benchmark Mac dictation solution.
via Mac OS X Hints