Android 4.1 includes offline voice typing. You can see this when you click the microphone on the pop-up keyboard, it still works if you have no network connection. However, it looks like the RecognizerIntent API still ends up requiring a network connection when you want to do speech recognition from your app.
Is there an API for accessing new the offline voice typing feature in Android from my app?
Android uses two different APIs for voice: voice typing (key on the keyboard) and voice recognition (everywhere else). Voice typing is enabled offline and voice recognition is not (for 4.1 JellyBean).
This is why the key in the keyboard works offline, but nowhere else does. For some reason Google decided to make these two separate APIs.
See here for more info on voice typing: http://android-developers.blogspot.com/2011/12/add-voice-typing-to-your-ime.html
来源：https://stackoverflow.com/questions/11893788/use-offline-voice-to-text-in-android-4-1-jelly-bean-from-my-application