It works Rounik!
Thank you for your tips about changing tempos.
Is there a Video explains how to remove the vocal from a song.? You have mentioned this in Forum. Since I am a beginner, I didn't understand very well. A video would be helpful.
I use Logic to record my students' voice.
The styles are : Jazz, musical, pop, rock and classical. Maybe you have some good ideas for voice recording. Please let me know.