Most homeowners spend months trying fix after fix. The answer is almost always the same and it has nothing to do with the walls.
You have tried the curtains. You bought the white noise machine. You even looked up whether moving was a realistic option. But the trucks are still rattling your windows at 6am, and the neighbor’s bass is still thumping through the wall at midnight.
Here is the part most people never hear: up to 90% of exterior noise enters a home through the windows, not the walls. Glass vibrates. Frames flex. And the double-pane windows that came with your apartment or house were never designed to block serious urban noise. They were designed to keep the weather out.
Understanding why changes everything about how you approach the fix. It is exactly the problem the team at Soundproof USA has been solving for over 25 years.
What type of noise are you actually dealing with?
Not all noise travels the same way, and treating them the same way is one of the most common mistakes homeowners make. Low-frequency noise from trucks or trains requires mass and decoupling to stop. High-frequency noise from voices or sirens needs an airtight seal. Most DIY solutions address neither properly.
Traffic and road noise
Low-frequency, constant
Neighbors and voices
Mid-frequency, variable
Aircraft and trains
Broadband, penetrating
Construction
Impact and airborne combined
Identifying your noise type first is critical. A solution that works well against voices may do almost nothing against a freight train two blocks away.
Why your STC rating is the number you need to know
Every window has an STC score — Sound Transmission Class — which measures how much sound it blocks. The higher the number, the quieter your room. Most people have never seen this number. Here is where things get eye-opening.
From the field
A standard double-pane window scores around STC 26 to 28. That means loud traffic is clearly audible. To actually feel the difference, you need STC 45 or above. Most premium replacement windows still fall short of that. A properly installed interior window insert reaches STC 48 to 54, which is where homeowners start describing their home as “finally quiet.”
Traffic clearly audible
26 to 28
Standard double-pane
Reduced but still disruptive
35 to 40
Premium double-pane
Traffic becomes a faint hum
48 to 54
Interior window insert
Why curtains, foam, and acoustic panels do not work
This is where a lot of money gets wasted. Acoustic foam panels are designed for echo reduction inside a room, not for blocking noise coming in from outside. Heavy curtains add a small amount of mass, but nowhere near enough to stop a 70-decibel truck. And foam tape around window frames addresses draft, not sound.
To block sound, you need two things: mass and an air gap. The same physics behind recording studios and professional soundproofed spaces. A 2-inch curtain provides neither in any meaningful quantity.
What a proper fix actually looks like
An interior window insert installs inside your existing frame, creating a second pane separated by a sealed air gap of 3 to 5 inches. That combination — laminated glass, a compression seal, and a trapped air pocket — is what decouples the sound energy from your living space. It works with your existing windows, not instead of them. No structural work, no permits, no change to the exterior of your home.
Installation typically takes a single day. Every unit is custom-manufactured to your exact frame dimensions, covering double-hungs, sliders, casements, and most other window styles. The inserts are removable, virtually invisible from inside, and also cut drafts and dust by up to 99% as a side benefit.
The specialists at Soundproof USA have been fitting these across the country for over two decades and offer a free in-home assessment to identify exactly where your noise is coming from and what will actually stop it.