system() slows down my camera's feedback

Question

I an working with opencv and Xtion Pro Live stereoscopic camera on a motion detection project (os: ubuntu 12.04). I have managed to detect the moving object, but i want to put a sound when the motion is detected.

I tried it with the

system("canberra-gtk-play -f gotcha.wav"); 

command. The code does properly what i want, but the feedback is slower. This results in hearing the sound more than once.

Is there another command that i should use? Could you please tell me why this command affects my camera's feedback?