Alright, I'll try this right now.
EDIT : Oh I see what you mean, but that is not exactly what I want. You see, there is a Variable called "Sound fight" or something and the choice of sound type in it is similar to the one in the Object editor. But there is no action where you can use this variable ! Here's mah problem.
Also, the solution that you give me is not a perfect one, because a sound created in the sound editor can not be played more than one time at the same time (hope you understand...).