I have a friend who was told in high school by the 'music teacher', that she was tone deaf and could not sing = but that did not stop her singing along. Fifteen years later, when I met her, she was all over the scale. I taught her the 'bend the ear' trick, and managed to get her listening to her own voice, along with what she was trying to sing with.

With much practice she HAS improved noticelably, but is occasionally off key - she just needs a little more focus, I believe.