How to increase the Apple Dictation timeout?
The official answer (which clearly isn't the one you want based on how the question is phrased) is no for OS X 10.8 and earlier. For the initial implementation, dictation on OS X was limited to 30 seconds of audio per transcription event.


Mac Basics: Dictation - HT5449 


Hopefully this helps others that are looking for an official answer or explanation. On OS X 10.9 (Mavericks), offline dictation and longer dictation are allowed and you can enable it by answering yes when asked if you want enhanced dictation. You can also control it by going to the Dictation tab of the Speech &amp; Dictation system preference pane: