HRESULT AutoGainEnableSet(DWORD dwAutoGain);
Sets the state of the automatic gain for the incoming audio stream.
· Returns NOERROR if successful, or one of these error values:
E_INVALIDARG
E_OUTOFMEMORY
SRERR_NOTSUPPORTED
SRERR_VALUEOUTOFRANGE
dwAutoGain
[in] Automatic gain value. This parameter can be SRATTR_MINAUTOGAIN or SRATTR_MAXAUTOGAIN for minimum or maximum allowable values, respectively.
A value of 0 disables automatic gain. A value of 100 causes the speech-recognition engine to always adjust the gain. Values between 0 and 100 moderate the gain on a linear scale. If the value is out of range for the engine, an error is returned and the gain is not changed.