I'm building a house and the master bathroom's shower and bath back up to another bedroom on the first floor. I was wondering what sort of extra insulation might I look into to try and reduce the noise the shower and bath will generage through the wall. Any suggestions to talk with my builder about.

Regular bat fiberglass insulation or rigid styrofoam might help a little but not much. Putting insulation on pipes might reduce the sound of water moving through the pipes.