Our inserts help reduce noise in most situations, but we want to ensure we are the right solution for you. Every space is different. Many factors affect the noise reduction performance of your inserts. This guide will help you understand how Indow inserts impact noise entering a space.
We’ve put this together based on customer feedback and third-party lab testing. This is a guide, not a guarantee.
Sound waves enter your space through every surface, gap, and crack: walls, doors, ceilings, floors, vents, and windows.

How close is it? The closer the sound source, the stronger the sound waves. You may perceive a smaller reduction in noise from nearby sound sources.
How high up are you? Upper floors of high-rises experience noise as if the source is closer due to the reverberation between buildings. This may cause a reduction in the noise mitigation of our inserts.
What is the frequency? Our inserts are more effective at reducing sound at high frequencies than low frequencies. For example, Indow inserts will reduce high-frequency sounds of train screeching on the tracks far more than low-frequency vibrations of its rumbling engine.
How Much Noise Can Indow Inserts Reduce
The groupings below show from left to right how much noise damping you can expect from the addition of Indow inserts. Those on the left will most likely have the biggest change in the noise heard inside the space. The average STC rating for our window inserts installed in a window is 42. All windows have the potential to get to that rating, but the situations on the right may have started closer to that STC rating before installing Indow inserts.

Note: We do not recommend Indow inserts for reducing noise coming through laminated glass windows, triple-pane windows or hurricane windows.
- Although Indow inserts may not provide as much of an overall noise reduction in the space as you are seeking, they are often one step on the path of a noise reduction strategy.
- To prevent an unsatisfactory install, make sure to fully evaluate your space and create an action plan that addresses your specific needs. Our Fit Specialists and Dealers can help with resources to get you started!
- Due to the custom nature of Indow inserts, all purchases are final and no refunds will be provided.
- Maximize space between insert and window.
- Address other sources of noise penetration.
- Treat all windows in a room with inserts.
Partial treatment is unlikely to produce notable results. - Be wary of apps on your phone for measuring noise levels (db).
Use a consistent noise maker to trace entry points.
- Standard Grade inserts reduced sound coming through operable single-pane windows by 10 dBa (50%). Acoustic Grade reduced sound by 18.9 dBa (70%) – Independent analysis completed by Portland State University
- Acoustic Grade inserts reduced sound coming through operable double-pane by 10-12 dBa. (approx. 50%). This yields a 42-45 STC rating, reducing a sound like loud speech to a murmur, or entirely inaudible – Independent analysis completed by BCIT Centre for Architectural Ecology, Burnaby, British Columbia, Canada
- Acoustic Grade inserts combined with operable single-pane yields an STC rating of 39, where loud speech can sometimes be heard, but not clearly – Analysis completed by NWAA Acoustical Laboratories, Elma, Washington
- Please note the lab measured dBa reductions came from an isolated test window and do not measure overall noise reduction within a room. Overall noise reduction depends on the amount of noise entering through all surfaces and openings. Even small openings can have large impacts.

We value safety and privacy. We will never share, sell, or rent your data to third parties not directly related to your purchase or consideration of our products. Read our full policy here.