I'd take a look at a window with laminated glass. Most major manufacturers offer them as an option. Make sure you get a good installation.

You may be confusing laminated glass with plexi-glass.

http://www.keepsafe.com/benefits/sound.asp

Not sure what there is to confuse. OBERON mentioned in another message about having a glass place cut 1/4" laminate glass to put in a diy frame and installing.

The original question was regarding "replacing the window" with something more sound-proof. Better sound insulation out of a 1" IG unit than a 1/4 piece of laminate. I also disagree with Oberons advice. While putting a piece of laminated glass into a basement window might be cosmetically OK, I'd be willing to bet most wouldn't find putting it into a bedroom window to be very attractive. Not to mention the potential hazard in the event of a fire if these are the only escape routes.

Sorry. I did mention replacement in my original post. I've had two quotes for replacing the windows. Both are right around $1000. For $1200 I could get windows from soundproofwindows.com which I'm assuming would be better because these would leave my current windows intact. One of the windows opens and the other does not.

What I am curious about is what the soundproofwindows.com windows consist of. If it is simply 1/4" laminated glass on a frame then it seems like something could be done for a fraction of the cost.

I think I'd lean more towards replacing the windows because I don't see much difference in the STC and U values between a good double pane with laminated glass and the Soundproof windows. Soundproof claims an STC up to 60 but says the average is 42. If you use the link to Keepsafe glass the STC is 40. As I'm sure they are quoting a center of glass U value, most any decent quality double pane glass window will get you to a .26 U. If you get it with E2 it gets you to .23 U.

It appears they have taken the idea in an internal storm window and added laminated glass to it. I'd have some concerns about condensation and rotting wood. If your existing windows are wood, you still have the problem with painting and cleaning to contend with.

So for $200. less, I'd just replace them with a 1" IG, E2, double pane w/ laminated and argon/krypton gas.

Pella has an industry pounding STC (sound transmission coeeficient) triple pane window that you will be tickled about. Be sure to use spray foam(low expansion) to insulate around the windows too

As I recall, in the post where I suggested mounting a laminated glass lite to the interior of the exisiting windows (as mentioned above), the homeowner was very specific in that they were only interested in blocking as much unwanted sound as they could through those windows and not worried about possible aesthetic considerations.

Firecodes are certainly important and must be considered whenever modifying a window or a door in a home. However, any interior (or exterior) storm window is going to affect egress through a window - whether the glass is laminated or not is a secondary issue that must also be seriously considered.

Soundproof windows in essense installs a laminated lite (or lites - in an IG configuration) to an exisiting window thus increasing the sound blocking capabilities of the window. That about covers it.

They get excellent STC numbers for two reasons - first, the laminated lite has significantly better sound blocking ability than does non-laminated glass - and second, the introduce an airspace between the exisiting window and the laminated "interior storm" window which also helps to significantly reduce unwanted sound.

A homeowner can do much the same thing, and achieve the same results at much less cost, by installing a sheet of laminated glass inside of an existing window...other considerations as mentioned in this and previous posts.

Also, an IG unit manufactured with two lites of 1/4" glass and with a 1" airspace has an STC of 37 while a single 1/2" laminated lite, also made with 1/4" glass and a .030PVB interlayer, has a STC of 38.

However, I personally don't care much for STC (as I have mentioned in previous posts), much preferring OITC - Outside Inside Transmission Class.

In the case of a 1/4" / 1" air / 1/4" IG, the OITC is 30 while the OITC for the 1/2" (overall) laminated lite is 34.

A laminated lite with 1/8" glass /.030PVB / 1/8" glass has an STC of 35 and an OITC of 31 - less effective than 1/4" glass and 1" airspace when comparing to STC number and more effective when comparing OITC numbers.