A Sound Transmission Class (STC) rating measures how much sound (in decibels) is stopped by a partition, such as a window or wall. It’s a way to tell whether one type of partition is better than another without having to take someone’s word for it. The higher the number, the better.

Why Is an STC Rating Important?

An STC rating matters because it’s not a subjective measurement. A specific method is used to calculate how much sound of various pitches passes through a partition. A brick wall will stop more sound than a paper wall – that’s obvious. However, if you’re unfamiliar with a certain type of material, such as the types of acrylic, it’s less obvious. That’s when STC ratings help.

Which Materials Have Higher STC Ratings?

Acoustic grade acrylic inserts have a lower STC rating than acoustic grade laminated glass. In other words, acrylic stops less sound from passing through than laminated glass. Why? Essentially, it depends on how dense the material is. The denser it is, the harder for sound waves to pass through. Brick is denser than paper. Laminated glass is twice as dense as acrylic. That’s why brick stops more than paper and laminated glass blocks more than acrylic.

Generally, when measured in conjunction with double-pane windows, laminated glass window inserts have an STC rating of 48. Acrylic window inserts rate 42. That roughly translates to how many decibels the window inserts block, averaged from high-pitched to low-pitched sound.

Usually, single-pane windows have an STC rating of 26 to 28 and double-pane windows have an STC rating of 26 to 32. This means you can easily hear loud speech through the window. While increases may seem small, each increase of 10 in an STC rating halves the sound. With an STC rating of 48, loud speech is largely inaudible.

What Does an STC Rating for Windows Mean for Your Home or Office?

Sun and Sound Windows’ soundproof laminated glass window inserts have an STC rating of 42 if you have a single-pane window and 48 if you have a double-pane window. The inserts help insulate your window from sound and weather, and they are even more effective if you have thicker windows.

Have questions about the types of sound our windows can block – from motorcycles to the bass guitar in music? We have answers, and we’ll give you a free estimate of how our windows can help.