Does Soundproofing Foam Work Both Ways? Understanding Its Effectiveness

Many people assume that soundproofing foam works both ways, meaning it can block external noise from entering a room while also preventing internal noise from escaping. However, there’s a key distinction between sound absorption and soundproofing, which greatly impacts how foam panels function.

If you’ve ever installed soundproof foam expecting total silence, only to find that noise still leaks in and out, you’re not alone. In this article, we’ll explore whether soundproof panels work both ways, what they’re actually designed for, and the best alternatives for true soundproofing.

Before diving into whether Acoustical Foam works both ways, it’s important to clarify what it actually does. Sound Absorbing foam —more accurately called Acoustical Foam—is made from open-cell melamine foam. Its primary function is to absorb sound waves rather than block them.

These foam panels are commonly used in:

AlphaSorb Acoustic foam is available in various designs, including wedge, pyramid, egg crate, and flat panels, all of which help diffuse and absorb sound waves.

The short answer: No, Acoustical Foam does not work both ways.

Acoustical Foam is not designed to block noise transmission between rooms. Instead, it helps reduce echo and control sound reflections within a space. This means that while it improves sound quality inside the room, it won’t prevent sound from entering or leaving the area.

The reason Acoustical Foam doesn’t work both ways is because it lacks the mass and density required to stop sound waves from traveling through walls, doors, and windows. Instead, it only absorbs certain frequencies that bounce around inside a room.

For example, if you install foam on your walls, it will make your voice sound clearer and reduce echo, but your neighbor will still hear your loud music, and external noise will still be able to pass through the walls.

To fully understand why Acoustical Foam doesn’t work both ways, we need to compare soundproofing and sound absorption:

If your goal is true soundproofing, acoustic foam alone will not be enough. Instead, you’ll need dense, high-mass materials and/or decoupling to effectively block noise.

If you need to completely block noise from entering or leaving a space, here are the best soundproofing solutions:

AudioSeal Mass-loaded vinyl (MLV) is one of the most effective soundproofing materials because of its high mass-to-thickness ratio. It can be installed inside walls, ceilings, and floors to block sound transmission both ways.

Doors are a major source of sound leakage. Adding PrivacyShield Door Seals helps eliminate gaps around the door frame, significantly reducing sound transfer.

For temporary soundproofing, thick PrivacyShield Soundproofing Blankets can be placed over doors, windows, or walls to absorb and block unwanted noise.

A more permanent solution involves adding a second layer of drywall with Double Drywall with Green Glue Compound. The Green Glue acts as a viscoelastic layer, breaking up sound vibrations and reducing noise transmission.

While Acoustical Foam helps control echo, it does not block sound transmission in both directions. If you need true soundproofing, you’ll need high-mass materials and decoupling materials like AudioSeal mass-loaded vinyl (MLV), Double Drywall with Green Glue Compound, PrivacyShield Door Seals, and RSIC(Resilient Sound Isolation Clips) Clips.

Looking for the best soundproofing solutions? Contact Acoustical Solutions today for expert recommendations and high-quality materials to achieve your noise control goals!