caring for a parrot takes a lot of time, money and commitment, especially cockatoos. have you ever cared for parrots before? it's great that you're taking this bird out of an undesirable situation. has he been to an avian veterinarian yet for a full examination?
one of my favorite books is
Guide To A Well-Behaved Parrot, by Mattie Sue Athan. this book is wonderful, and covers all sorts of behavior problems from biting to screaming and for your case, weaning off obnoxious noises. a must read for every parrot owner!