Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Filename
GV_SOUND_FILENAMEParameter: Probe
GV_SOUND_PROBEParameter: Play
GV_SOUND_PLAYParameter: Time
GV_SOUND_TIMEParameter: Sample
GV_SOUND_SAMPLEParameter: Left
GV_SOUND_OUTPUT_LEFTParameter: Right
GV_SOUND_OUTPUT_RIGHTParameter: Length
GV_SOUND_LENGTHParameter: Samples
GV_SOUND_SAMPLESParameter: Bands
GV_SOUND_FFT_RESParameter: Band
GV_SOUND_FFT_BINParameter: Left Mag
GV_SOUND_FFT_BIN_LEFTParameter: Right Mag
GV_SOUND_FFT_BIN_RIGHT