Re: Genie's question (the person who can play in tune but not sing in tune): Sometimes people have to hear the melody notes in their exact range -- they get thrown off by octaves or even overtones because the notes don't sound exactly the same. Mathieu covers this in his book. If your friend is a man, get a man with the same vocal range to match notes with him -- tenor with tenor, bass with bass, etc. That should help. If it doesn't, have him have his hearing checked for certain frequency losses. If his hearing is O.K., it's an anxiety-problem or a listening problem and he can improve.