Enhanced Dictation

You’ll usually need an internet connection to use Dictation, since the processing is done on Apple’s servers. To use Dictation offline, you need to enable Enhanced Dictation. Go to System Preferences > Dictation & Speech > Dictation tab and check the box marked Use Enhanced Dictation. Your Mac will download a file (a few hundred megabytes in size) so it can do the processing and provide you with live feedback.