Calculate mass-loaded vinyl, soundproofing drywall, or acoustic insulation by area and layer count.
Usage Tip
Stagger seams between layers and seal edges with acoustic caulk; gaps undo much of the benefit.
The order quantity multiplies area by layers, then adds waste.
Soundproofing vs Sound Absorption (They Are Not the Same)
This is the single most common mix-up, and it sends people to the wrong product. Sound absorption – foam and acoustic panels – reduces echo and reverb inside a room. It does almost nothing to stop sound passing through a wall. Soundproofing – mass, insulation, decoupling, damping – blocks sound transmission between rooms. If you can hear a neighbor or a TV through the wall, foam panels will not help; you need mass and isolation. If your own room echoes, that is when panels are the answer.
STC Ratings Explained
STC (Sound Transmission Class) rates how well an assembly blocks airborne sound – higher is better, and a few points make a real difference.
| STC | What you experience |
|---|---|
| 30 | Normal interior wall – normal speech understood through it |
| 40 | Loud speech audible but muffled; conversations reduced |
| 50 | Loud speech barely audible; good isolation |
| 60+ | Excellent – most sound blocked, music heavily reduced |
Common Wall Assemblies
| Assembly | Approx STC |
|---|---|
| Standard wall (1/2 in drywall both sides, no insulation) | 33-35 |
| Insulated wall (mineral wool in the cavity) | 39-42 |
| Double drywall + Green Glue | 50-60 |
| Resilient channel / sound clips + insulation + double drywall | 55-60+ |
Soundproofing Materials & Effectiveness
| Solution | Effectiveness (transmission) |
|---|---|
| Acoustic panels / foam | Low – absorption only, not a barrier |
| Cavity insulation (mineral wool) | Medium – fills the air gap |
| Second layer of drywall (mass) | High – mass blocks sound |
| Green Glue (damping) | High – converts sound to heat between layers |
| Resilient channel / sound clips | Very High – decouples the wall |
The four real levers are mass (more drywall), damping (Green Glue), decoupling (resilient channel or clips), and absorption in the cavity (insulation). Stacking them is how you climb from STC 35 to 55+. Acoustic panels are not on that ladder – they are for echo.
How to Soundproof by Noise Type
- Voices / conversations: insulation plus a second drywall layer usually gets you there (STC ~45).
- TV noise: add Green Glue between the drywall layers (STC ~50).
- Music / bass: low frequencies are hardest – you need decoupling (resilient channel/clips) plus mass and damping (STC 55+).
- Home theater: the full stack – decouple, insulate, double drywall with Green Glue.
- Footsteps / impact (upstairs): this is impact noise (rated IIC, not STC) – treat the floor above with underlayment and carpet; wall work alone will not fix it.
Cost & What to Expect
Soundproofing is priced per square foot of wall and climbs with the STC target. Adding insulation is cheap; Green Glue and a second drywall layer are moderate; resilient channel or sound clips add labor as well as material. Expect a realistic single-wall retrofit to run a few hundred to a couple thousand dollars depending on size and target. The calculator estimates the materials cost and the cost per square foot for the assembly it recommends.
Frequently Asked Questions
What is the difference between soundproofing and acoustic panels?
Acoustic panels absorb echo inside a room; soundproofing blocks sound passing through walls. For a noisy neighbor you need soundproofing, not panels.
What STC do I need?
About 45 to reduce conversations, 50 for TV noise, and 55+ for music and home theater. The calculator sets a target from your noise type and room.
Does insulation soundproof a wall?
It helps – mineral wool in the cavity adds a few STC points – but on its own it is not enough; pair it with mass and damping.
What is the best way to soundproof an existing wall?
Add a second layer of drywall with Green Glue, ideally on resilient channel, over an insulated cavity.
How do I stop footsteps from upstairs?
That is impact noise – treat the floor above (underlayment, carpet, or a resilient ceiling), not just the wall.
Will one product solve my noise problem?
Rarely – soundproofing works by stacking mass, damping, decoupling, and insulation together.
Related Walls & Acoustics Calculators
Note: STC values, improvements, and costs are planning estimates – real-world results vary with construction, flanking paths (sound travels through floors, outlets, and gaps), and workmanship. A wall is only as good as its weakest path, so seal gaps and treat outlets. Impact noise (footsteps) is rated separately (IIC). General DIY guidance, not an acoustic-engineering specification; for critical builds consult an acoustician.