Sound Blocking: Why just airspace won't block sound

Source Post: http://www.replacement-windows.com/windowbb/viewtopic.php?p=2406

You're welcome, but I am curious what your specific need is for that sort of gap? I suspect that you will probably need to use something like the sound-blocking panel that was mentioned in order to get that sort of construction, ultimately.

A few numbers for comparison:

The lite I mentioned in the previous post was 1/8" btw...I forgot to mention that. Also, I can spell "bass" as in musical instrument, but I was a bit rushed when I was finishing that post...

The following figures were derived by the Riverbank Acoustical Laboratory and were determined from transmission loss data based on requirements of ASTM E413 (there goes the official disclaimer!)...

A monolithic laminate 1/8 x .030 x 1/8 = STC 35

1/2 IGU -- 1/8" x 1/4"AS x 1/8" = STC 28 (AS = airspace)

change one lite to the laminated make up mentioned and the STC is 35, the same as the monolithic laminated lite. Note the numbers as related to the 1/4" air space?

1-1/2" IGU -- 1/8" x 1" AS x 1/8 = STC 37

kick the airspace up to 4" and the STC rises to 44, or leave the AS at 1" and change one lite to laminate and you have an STC of 42.

If you were to change both lites to laminated and use the 1" airspace, your STC would be 46.

Finally, if you were to use a 4" airspace with two laminated lites, you would achieve an STC of 53, which is a heck of a lot better than your typical wall.

Again, with the understanding that these numbers are based totally on IGU performance and that actual performance in the field will be extremely dependent on the construction and especially on the quality of the installation of the window....and also that STC is an "averaged" figure and does not relate to specific performance at specific frequencies. It is entirely possible that a window with a higher STC of one particular make up might not perform as well as a window with a lower STC and a different make up at blocking specific sounds or frequencies.

Source Post: sound proof windows
http://www.replacement-windows.com/windowbb/viewtopic.php?p=2406
Posted: Sat Mar 26, 2005 7:24 pm