Trying to decide on windows for sound reduction

[evanmarks]

Hi everyone -

My house is near the corner of a fairly busy intersection and I am looking to replace some windows with the goal of better sound control. Using a decibel meter on my phone, it seems like the normal traffic noise is about 65 db with the window open, and about 50 closed when a car goes by. Spikes with the window open are up to 84 db.

The current windows are doubled paned with two panes of 3/32" and a gap of 13/32" from a brand called Plygem. I got them on the phone and they quoted the STC rating at 28. The windows are also installed quite poorly with a large gap between the block frame and the window opening (aluminum frame in between) so that may be a factor as well.

Quietline windows are out of my price range, so I'm trying to find out what my options here are. So far I've gotten quotes for two versions of Simonton's Daylight Max windows. One has 1/8 over 3/16 panes with a 5/8 spacer - STC of 34. The other is laminated (not sure of pane thickness) with an STC of 35.

My questions are - is there a major difference between these two windows for blocking out traffic noise? Is there a way to get the transmission loss results from testing to see how they perform in various frequency ranges? Any other better options short of springing for the Quietline?

Thanks,
Evan Marks

[masterext]

Evan
The debate over sound reduction is somewhat contentious amongst various window experts. However, one thing is certain, laminated glass is the best option for eliminating sound. The more contentious aspect of this subjuct has to do with triple pane glass which some pro's view as providing very little, if any improvement in sound reduction over double pane.
My view based on experience is that triple pane glass obtains much more sound reduction than the stc numbers may lead you to believe. Adding an additional pane is adding more mass which invariably reduces sound, its that simple. I have actually talked with engineers with various glass companies who seem to concur.
Triple pane is much more cost effective than laminated and i steer many of my sound conscious customers to triple pane for that very reason. That said, if they reside next to an airport, train station, railroad track, or extremely busy street, i then offer laminated due to its superior stc.
Other things to bear in mind are foam filled frames, non metal spacer systems, and air tight installs all collectively aid in reducing sound.

[evanmarks]

Thanks masterext. It seems like you are implying that the laminated is the way to go? Is the 1 point STC difference between it and the dissimilar glass pretty accurate at describing the difference in sound control, or does the laminated before significantly better in practice?

[masterext]

Laminated is the " gold standard" when looking for maximum sound reduction. As i alluded to earlier, triple pane glass is a much less expensive alternative if the noise level isnt out of control.