Enhanced (local) dictation in Mavericks 10.9 not working
It's possible the Enhanced Dictation language pack was corrupted when it was downloaded. You could try deleting it and re-downloading it.

First, turn off Enhanced Dictation in System Prefs > Dictation. When you uncheck the box a panel will slide down that you can just Cancel (which will turn Dictation off). Next, open Finder and press shift-command-g simultaneously. In the dialog box paste the following and click go:

/System/Library/Speech/Recognizers/


In the Recognizers folder there will be two folders. Delete (or rename) the folder called SpeechRecognitionCoreLanguages. It will ask you for your password to delete (or rename) the folder. After that you can go back to System Prefs > Dictation and turn Enhanced Dictation back on. It will show you your download progress in the bottom left corner of the System Prefs window.