How can voice search improve recognition
Try this Can I train Google Voice Actions to better recognize my voice?

Digging around Android forums and elsewhere, I found a good number of testimonies from speech-to-text enthusiasts who saw better results from simply speaking at a normal clip. Google representative Nadja Blagojevic offered much the same advice for the search giant's voice product in both Android and its Chrome browser: "Speak naturally and clearly, but don't strain to enunciate too much or speak slowly."

http://lifehacker.com/5825965/speak-faster-to-improve-voice-recognition-apps

http://forum.xda-developers.com/showthread.php?t=630707