How can I stop a loud wailing crack coming from my plumbing? I recently bought a Victorian house which have been replumbed. Every...

I recently bought a Victorian house which have been replumbed. Every time I flush the upstairs toilet a loud wailing echo goes right through the house. Whats the result in and how can I stop it happening?
Answers:    replace the steep valve surrounded by the commode, many times a compress valve will squeal and moan, especially if it is the bubble float type, that is the most simple and easiest place to start, best of luck
Open and close the angle stop.