If you are not sending up a audio file in wave format, and instead you have just raw data, then before sending up any audio data, you must first send up an SpeechAudioFormat descriptor to describe the layout and format of your raw audio data. The audio must be PCM, mono, 16-bit sample, with sample rate of 8000 Hz or 16000 Hz.

void SendAudioFormat(
	SpeechAudioFormat audioFormat
)

Sub SendAudioFormat ( 
	audioFormat As SpeechAudioFormat
)

void SendAudioFormat(
	SpeechAudioFormat^ audioFormat
)

abstract SendAudioFormat : 
        audioFormat : SpeechAudioFormat -> unit