Because everyone has a noise problem and soundproofing seems intuitive, it attracts more folk myths than almost any other building topic. Most of the myths share a root cause: confusing controlling echo inside a room (absorption) with stopping sound passing between rooms (insulation), and underestimating how thorough you have to be. Here are the mistakes that matter.
Myth 1: egg boxes and foam stop noise
The most enduring myth. Egg boxes, acoustic foam and soft panels on a wall do essentially nothing to stop sound passing to the next room — they're lightweight, so they have no mass to block transmission. What they do (foam, properly) is absorb echo and reverberation within a room, changing how the room sounds to someone inside it. Useful for a home studio's acoustics; useless for stopping your neighbour hearing you. This is the absorption-vs-insulation confusion in its purest form.
Myth 2: 'acoustic' or 'soundproof' paint
A thin coating of paint, however marketed, adds negligible mass and provides no decoupling, so it cannot meaningfully reduce sound transmission between rooms. It's one of the clearest examples of a product promising what physics won't allow. Save the money for mass, decoupling and sealing.
Myth 3: one product / one surface will fix it
Soundproofing is a system, not a product. The belief that a single magic board, mat or spray will solve a serious noise problem ignores the four principles (mass, decoupling, absorption, damping) and, fatally, flanking. Real solutions combine principles and address every significant path — which is why a thin, single-surface, product-led approach so often disappoints.
Mistake: ignoring flanking and gaps
The two commonest practical failures:
- Ignoring flanking — treating the obvious party wall while sound flanks around it through the floor, ceiling and junctions, so the result barely improves (see the flanking article).
- Leaving gaps — an unsealed socket, a poorly-sealed perimeter, a letterbox, a gap under a door. Airborne sound, like water, pours through the smallest opening, and a single gap can undo an otherwise good treatment.
| Common belief | Reality |
|---|---|
| Egg boxes / foam block noise | They absorb echo inside a room; they don't stop transmission |
| Acoustic paint soundproofs a wall | Negligible mass, no decoupling — no real effect |
| One product solves it | Soundproofing is a system of combined principles |
| Just treat the party wall | Flanking through floor/junctions often dominates |
| Mass alone fixes bass | Low frequencies need decoupling and damping too |
Mistake: confusing mass with the whole answer
Mass is essential, but mass alone is an inefficient way to tackle low frequencies — you'd need impractical weight to stop bass by mass alone. The bass that bleeds through walls needs decoupling (an air gap / resilient break) and damping, not just heavier board. Expecting a mass-only upgrade to solve a heavy-bass problem is a common, expensive disappointment.
What actually works
Myth: thicker plasterboard alone is the answer
A subtler mistake than egg boxes is the belief that simply screwing more, or denser, plasterboard directly onto an existing wall will solve a serious problem. Mass genuinely helps, and the mass law means more weight does improve airborne insulation — but with diminishing returns, and only modestly against the low frequencies that cause most complaints. Worse, boarding directly onto the existing wall keeps the two leaves rigidly connected, so there is no decoupling, and the extra mass can even shift the wall's resonant dip into a more audible range if it is not paired with damping. A mass-only upgrade can take a mild speech problem from annoying to acceptable, but it will not stop a neighbour's subwoofer, because bass needs an air gap and a resilient break, not just heavier board. Expecting heavy board alone to defeat bass is one of the most common and expensive disappointments in DIY soundproofing.
Realistic expectations — what soundproofing can and can't do
Honesty about outcomes is itself part of good practice, because much disappointment comes from expecting silence. Retrofit soundproofing reduces noise; it rarely eliminates it. In an existing building you are working with flanking paths you cannot fully break, junctions you cannot rebuild and a finite depth you can give up, so a realistic goal is to take an intrusive problem down to a tolerable one — turning clearly-audible speech into an indistinct murmur, or sharp footsteps into a soft, occasional thud — not to achieve a recording-studio hush. The most effective interventions are often the least glamorous: cooperating with the neighbour above to add a resilient underlay, sealing the gaps and upgrading the door, and treating the dominant flanking path rather than the obvious surface. A treatment designed around the actual dominant paths, with the four principles combined and every gap sealed, delivers a genuine, worthwhile improvement; a product bought in hope of silence delivers a bill and a lingering noise. Setting the expectation correctly at the outset is the difference between a satisfied outcome and a disappointed one.
