I brought a lot of buddies in the second volcano and started a song. Then the tubes throw a lot of audio materials and the message tells me that I have to repair the defective tubes in order to let the buddies sing well.
How do I repair the tubes ?

I don't understand entirely which of volcanoes do you mean. But one of them needs you to start the music(key enter) and then plug wrong vuvuzelas(they are marked by the X) by some stuff in that room. And the second needs you to use the terminal in it's room and play in game like a guitar hero, then, after success, you have to correct angle of drums in near room.
PS: My english is not good. I hope you'll understand what I mean.

I throw stuff to block the vuvuzelas, but they throw it out after a while and I cannot block all the pipes before the music stops

Yet this is exactly what you are supposed to do. Try to stop them up quickly. The mini-game turns incredibly hard when there are 4 or 5 broken vuvuzelas throwing stuff at you. It's better to plug them with some garbage before another broken vuvuzela starts honking.

Throw barrels.

Thanks. It finally worked.