On the last mission, when you first enter the village after blowing up and exfiltrating the STG44 place, enter the village, killing everyone as you go. when you enter, make a left at the first street, and enter the second door on your left (the first door is locked). Walk into the room, turn right into the hall, then enter the room on your right with the cello and the piano. Try pressing either 'e' or the assaigned action key to hear the Medal of Honor theme played on either instrument. press 'e' or action when the first part of the song is finished to hear the next part.