Why do wolf tones exist? And what is the reason for their sound?

And also, how does one judge recordings to be good or bad? What criteria is to be used?

I just get the idea that I don't have enough time with my teacher to discuss various musical phenomena.

Because that's what I've been trying to do. Every lesson I go to him with questions, not just about cello technique but also about the world of music, and he answers them as well as he can. Unfortunately all I get with him is a paltry one hour every week which is hardly enough to talk about string economics and orchestral procedures in addition to receiving musical and technical direction.

Maybe I shall quiz Mr Foo tomorrow...