In reply to irene46.

Voice coaching can save a voice IF the singer wants the voice to be saved, which doesn't seem to be Christina case. I can pretty much guarantee you that under my tutelage (or someone strict like my voice teacher) her voice would be in shape within 3 months or less IF she wanted to cooperate.

And sure, you dislike Beyonce's screechy vocal tambor when she pushes her voice, but she still manages the ever ascending key of "Love on top" without choking as Christina would do.