Sound reduction is the major "unexpected" benefit after installation of our storm windows. Many people are surprised at the dramatic reduction in outside noise.
Certain glazing materials provide superior sound reduction characteristics. The most popular of these is laminated glass, which has a PVB inter layer between two pieces of glass.
There are several methods for measuring sound characteristics, the most common of which is a Sound Transmission Class or "STC" rating. Our storm windows (with 3/16" laminated glass) have been field tested on several projects, and were found to meet the stated criteria for that project.