Busting the Myth – Pyramid Vs Wedge-Shaped Acoustic Foam

When soundproofing a domestic or commercial building, it’s a given that you want the best possible solution to meet your acoustic requirements. Acoustic foam is a popular choice, and there are many considerations that need to be made when deciding on the most suitable product. However, a persistent myth pervades that there is a fundamental difference in performance between pyramid and wedge profiles.

Pyramid and wedge-shaped acoustic foams are both sound absorption-based solutions, and both use open-cell technology; there is no difference in performance when it comes to soundproofing.

The science

Acoustic foam operates on the principle of attenuation, or the gradual loss in intensity of energy when it passes through a medium. If you want to get really technical, it increases the surrounding air resistance, which in turn reduces the amplitude of incident sound waves and converts the sound energy into a small amount of heat.

In layman’s terms, that means absorption. Light is attenuated by sunglasses, X-rays are attenuated by lead, and sound is attenuated by foam.

The other type of soundproofing solution is acoustic diffusion, where energy is dispersed but not absorbed. Pyramid and wedge-shaped acoustic foam are not diffusion-based solutions; they are only and always absorption-based solutions. Whether a foam is pyramid or wedge-shaped makes very little difference, as the physical process occurs on the scale of individual foam cells, not that of the foam’s profile.

Where did the myth come from?

The myth likely originates from considerations much less grounded in the world of physics or soundproofing performance.

In order to differentiate between themselves, manufacturers produce different-shaped foams to stand out in the crowd. You can shape, twist, cut and colour acoustic foam any way you want, and by claiming that pyramid and wedge-shaped profiles produce different results, you can market a product as being superior in its treatment of acoustic waves.

Whilst it’s true that choice of material, foam thickness, cell size and porosity are important considerations depending on the frequency of sound you want to treat, whether you choose a pyramid or wedge profile doesn’t make a difference. The reality is that acoustic foams in pyramid and wedge-shaped configurations perform in exactly the same way regardless of their profile or colour.

So there you have it, one myth busted. Pyramid and wedge-shaped foams perform in exactly the same way using exactly the same technology. Any differences between them are purely cosmetic, and often a means by which manufacturers can differentiate between their products.