Acoustic insulation: myths and facts to consider before getting started

soundproofing has been gaining increasing prominence in residential projects, especially in large cities, where external noise can directly affect comfort and quality of life. However, despite the topic’s popularity, there are still many questions — and even misconceptions — about how it works in practice.

Nem toda solução visível garante silêncio: entender a diferença entre absorver e bloquear o som é essencial no isolamento acústico. (Freepik/Divulgação)

Many people confuse soundproofing with acoustic treatment, believe that simple solutions solve complex problems, or invest in unsuitable materials expecting miraculous results. That’s why, before starting any intervention, it’s essential to understand what really works, what is myth, and what the limits of each solution are.

1. Does acoustic foam solve every problem?

Myth. One of the most common mistakes is believing that acoustic foam panels are enough to block external noise. In fact, this type of material is more suitable for acoustic treatment, that is, to improve sound quality inside a project, reducing echo and reverberation.

Espuma/Lã de fibra de vidro: material leve e resistente, amplamente utilizado para isolamento térmico e acústico em projetos de construção e decoração. (REEnergizeCO/Divulgação)

For soundproofing — which prevents sound from entering or leaving — you need to invest in more robust solutions, such as higher-density walls, drywall systems with mineral wool, or double glazing. Therefore, foam can complement the project, but it will rarely be the main solution.

2. The heavier the material, the better the insulation

True. One of the basic principles of soundproofing is the so-called “mass law”: the greater the density and weight of the material, the greater its ability to block the passage of sound.

Materiais mais densos e bem aplicados fazem toda a diferença na redução de ruídos dentro de casa. (Biolã/Divulgação)

This explains why concrete walls, solid bricks, and solid doors perform better compared with lightweight materials. However, weight alone does not guarantee total efficiency — how materials are installed and combined also makes all the difference.

3. Sealing gaps makes a big difference

True. Small openings, such as gaps in doors, windows, or outlets, can significantly compromise the soundproofing of a project. Sound travels easily through these spaces, making any structural effort less effective.

Pequenos detalhes, como vedar frestas em portas e janelas, podem melhorar significativamente o conforto acústico do ambiente. (Reprodução/Divulgação)

That’s why investing in weatherstripping, specialized rubber seals, gaskets, and even heavier curtains can bring noticeable improvements. Although they don’t replace a complete project, these solutions are accessible and help reduce noise day to day.

4. Soundproofing completely eliminates sound

Myth. It’s important to set expectations: soundproofing does not completely eliminate noise, but rather significantly reduces its intensity.

O isolamento acústico não elimina totalmente os sons, mas transforma a casa em um espaço muito mais tranquilo e agradável. (Portal Acústica/Divulgação)

Even in professional projects, there will always be some level of sound transmission, especially at lower frequencies, which are harder to block. The realistic goal is to achieve acoustic comfort, not absolute silence.

5. You can soundproof without construction

It depends. There are practical solutions that can improve acoustic comfort without major interventions, such as rugs, thick curtains, movable panels, and shelves filled with books. These elements help absorb part of the sound and reduce reverberation.

Beatriz Quinelato Arquitetura - Sopro. Projeto da CASACOR São Paulo 2025. (Denilson Machado, do MCA Estúdio/Divulgação)

However, when the issue involves intense external noise — such as traffic or neighbors — it will hardly be possible to solve it completely without some type of construction or structural intervention. In such cases, the ideal approach is to seek professional guidance to assess the best alternatives.

CASACOR Publisher is an exclusive content-creation agent, developed by the CASACOR Technology team based on the knowledge base of casacor.com.br. This text was edited by Yeska Coelho.