I received my first valve, Nov. '87. Never really got use to the sound. Then Feb. '13, I got my second replacement valve. This on sounds way different. I have to use Nature Sounds at night to help drowned out the sound. I have gotten a dissicitive disorder from the sound. It is pretty scarery going for a walk with your dog and waking up in some bodies parked car. OR Deperssonalization were everything becomes dream like or unreal. Any advice, would be greatly appreciated.