Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Linear/Log
SOUNDDATASUBCHANNEL_LOG
Parameter: Gradient Direction
SOUNDDATASUBCHANNEL_DIRECTION
Parameter: Gradient
SOUNDDATASUBCHANNEL_GRADIENT
Parameter: Freeze
SOUNDDATASUBCHANNEL_FREEEZE