One of the lesser known features of Mavericks is an upgrade to the Dictation Software. In 10.8 Dictation was available but required an internet connection so that it could contact Apple Servers to translate speech to text.
In Mavericks, Apple have added Enhanced Dictation which is a worthwhile initial 490MB approximate download which gives you the ability to have offline Dictation. Even better, the translation is almost instant and because it is done locally you can live edit the dictated speech. Unlike dictation in 10.8, when using enhanced dictation, you aren’t limited to a 30 second recording.
To enable this feature navigate to System Preferences > Dictation and Speech.
In the Dictation tab, turn Dictation On and then select “Use Enhance Dictation”.
This should start the Download and Install the local Dictation Files. You should then be able to chat away to your hearts content.
If you find you are having issues with Dictation not working, it is possible that the data that has been downloaded may have become corrupt. The Download is stored in /System/Library/Speech/Recognizers within a folder called “SpeechRecognitionCoreLanguages” which contains all the dictation data.
If you turn Enhanced Dictation off and select cancel in the dialogue window to disable dictation.
You can then remove the “SpeechRecognitionCoreLanguages” folder and re-enable dictation and the “Enhanced Dictation” Feature this will then re-download the software required.