When we run water in the shower, there is no particular noise in the bathroom, but there is a loud whine (not a rattle or low vibration, but a high-pitched noise) in the basement near the pipes leading to the bathroom, and also in the attic which is supplied by the same pipe run. A muted version of the same whine can be heard all over the house.
I know this can be due to a number of things, but what should I try first?