acoustical glass ratings

When shopping for new home windows we don’t often consider the acoustical glass ratings of the product. In fact, for most home owners it is the farthest thing from your mind. But if you live in a noisy urban area of if your home is located close to a freeway, railroad, or simply adjacent to a busy street, you may want to ask for the acoustical glass ratings before you buy your new windows.

What Influences Acoustical Glass Ratings?

Acoustical glass ratings, and the related performance of windows and doors is influenced by several factors beyond the glass itself. The engineering design, framing material, and overall construction of the window assembly have a direct effect on the acoustical performance of the unit. The nuances of the overall design of a window assembly can lead to a reduction in sound attenuation by as much as much as 3 dB.


There are two basic methods used to determine the acoustical glass ratings of windows and doors. Both the Sound Transmission Class method (STC) and the Outdoor/Indoor Transmission Class method (OITC) measure the transmission of sound attenuation based on the dB scale. In each case the higher the STC rating or the higher the OITC rating, the greater the sound attenuation value of the window itself.


Sound Transmission Class (STC): The STC testing is based on noise with a specific frequency ranging from 125 Hz to 4000 Hz. This would encompass the typical sounds generated in or around your home.

Outdoor/Indoor Transmission Class (OITC): The OITC testing covers a wider range from 80 Hz to 4000 Hz. This wider range, and in particular the lower frequency levels of the OITC testing, captures lower frequency sounds such as road noise. So if you live on a busy street or near an interstate highway, you will want to consider the OITC rating of your windows and doors.

Decibel (dB): The dB rating of ambient noise is a measure of the amplitude of the sound. In layman terms, it is a measure of how loud a particular noise is. The larger the dB value, the louder the noise. Or in the case of the acoustical glass ratings of glass, it is the measure of how much the noise level is reduced as it passes through your windows and doors.

Argon Gas vs Krypton vs Air

When testing insulated glass with various gases filling the air gap between the glass, there is no appreciable difference in the sound attenuation value of the glass. There is no significant difference in sound ratings between windows filled with Argon and those filled with air.

Contact Us:

If you need further information about the acoustical glass ratings of your next window purchase, and you want advice on which product is best suited for your specific application, contact, One Source Glass LLC at or give us a call at (815)-725-7033.