[Zeke]

This is what I do for a living, sell and install replacement windows. First off, I wouldn't purchase through Lowes or the Home Defect. You can do better on price and leave a little on the table for a quality installation by an independent contractor. Do your research on any contractor. The actual Pella Window Store is a franchise of Pella and have their own employees in most cases. Not saying they are the cheapest, but they know Lowes is just across town.

Most other brands like Andersen are not franchised with the exception of one Anderson product, Andersen Renewal, a composite material frame.

All glass is the same. You can Goggle all day long about glass and learn a ton of info about noise control, energy, etc. The best thing about ANY new window is the weatherstripping. Think about it. Your cars have single panes of glass, yet the car is much quieter inside (with the engine off) with the windows up rather than even cracked open. Sound travels through air space, even between dual panes. There is no sound in a vacuum.

Yes, the windows can vibrate in harmonics. Sometimes we use 2 different thicknesses in the dual pane assembly to change those harmonics. And, we can use laminated glass (like your windshield) as one of the panes. A single sheet of 1/4" lammy has the STC (sound transmission control, a good Google term) as 2 panes of 1/8th spaced at a 1/4". Go to Safetylite for that info. Definitely get LowE or LowE Squared.

I could go on and on all day about this. Shoot me some specific questions.