No, this is pretty common and is why I use mainstream power conditioning. I always can hear when I'm not using my big Furman.
I personally have not heard the specific voltage issues you do, but we are at the mercy of the power company and our neighbors. 116 to 123 V is considered normal regulation. That is, well within the power company's spec. If you want to correct this, you'll need a "voltage regulator." Be careful to check that it will be better than this. Some regulators may do nothing between 115V and 125V. Lots of power conditioners do no voltage regulation at all. VR takes iron, and is therefore more expensive.
The other thing that may be happening may not be the absolute voltage but the amount of noise coming in.
Best,
E