The link to EMDR given earlier has died. Here's a more recent one:

PDF about voice teaching at the Royal Conservatoire of Scotland

In general, it seems to be a more heavyweight approach for more intractable problems than anything MacColl's crowd would have had to deal with (though it can work fast if you get lucky). Lots of links on the web about it. If the RCS has put its weight behind it, I'll believe there's something to it (though presumably there are also a lot of "therapists" in the business for a quick buck).