Specifies the type of request to make to the speech recognition service.

In Short Phrase mode, an utterance may be up to 15 seconds long. As data is sent to the service, the client receives multiple partial results and one final multiple N-best recognition result. The N-best result represents the recognition service's best estimates of what was actually spoken.

In Long-form Dictation mode, an utterance may be up to 2 minutes long. As data is sent to the service, the client receives multiple partial results and multiple final phrase results based on where the recognition service thinks sentence pauses occur in the audio stream.