If I understand correctly:
You will need to record onto 2 separate tracks, one receiving your voice as audio, the other receiving the played notes as MIDI.
If you are hearing the played notes, then maybe the Akai is generating that locally? (turn off Direct Monitoring or Local Mode or similar on the Akai?).
Otherwise, a connection diagram as shown here would help:
http://forum.cockos.com/showthread.php?t=140670