Do Soundproof Foam Panels Work?
Updated
Soundproof foam panels work on echo but not on noise coming through walls. A 2 in. foam wedge soaks up about 75% of the mid-range sound that hits it (NRC 0.75, Auralex Studiofoam Wedge (opens in a new tab)). But even the 3 in. version weighs just 0.27 lb/sq ft in Auralex's lab report (opens in a new tab), which is way too light to stop sound passing through a wall.
So do soundproof foam panels work? If your room rings on video calls, yes. If it's the neighbor's TV, no.
Example: A full extra layer of 5/8 in. drywall (2.2 lb/sq ft, USG (opens in a new tab)) only took an insulated 2x4 wall from STC 34 to 37 in USG lab tests (opens in a new tab). A 3 in. foam panel weighs 0.27 ÷ 2.2 = 12% of that layer.
For echo, thickness is what counts. At 500 Hz, 1 in. foam absorbs 0.30 of the sound (Auralex 1 in. report (opens in a new tab)) and 3 in. foam absorbs 1.06, so get 2 to 3 in. for voices and calls. Thin 1 in. tiles mostly catch the high end. Which products to buy is in which foam is best for soundproofing, and shapes and fire ratings are in soundproof foam panels.
For noise from next door, seal up the gaps around doors and outlets first, then add mass to the wall. The soundproof panels guide shows what really blocks sound, and the soundproof panels FAQ picks up the next questions.