We have a bidet at my parents house that has recently taken to singing at the pipeline.. sounds like it is coming from the valve and not inside the wall.. it stops when you flush the toilet next to it.... is it just a faulty valve? Air in the pipes? Been going on for a bit of time now and its just soooo annoying. It only happens where the bidet is installed, and sometimes comes on on its own and other times when someone uses a faucet somewhere else in the house.. Need to find the problem and correct, any help?