Sound insulation of the cabin

Professional Definition

The acoustic insulation of a cabin is the ability of its partitions (walls, ceiling, floor, doors) to limit the transmission of acoustic energy between the interior and the surrounding environment. This parameter is most often described as the weighted difference in sound pressure levels ($D_{n,w}$ or $R'_w$), expressed in decibels (dB).

In engineering practice, this means the measure of noise reduction provided by the complete structure. The acoustic insulation is influenced by the mass of the materials used (according to the law of mass), the multilayer structure of the partitions, and, crucially, the tightness of the joints and seals. Even a small leak can drastically lower the resulting insulation parameter of the entire cabin, creating so-called acoustic bridges.

Acoustics in Simple Terms

Imagine an acoustic cabin as a sealed thermos. Just as a thermos keeps the temperature of a drink, preventing heat from escaping outside (or cold from entering), the cabin is meant to keep sound inside. To achieve this, its walls must act like a solid dam on a river.

If you build a dam with heavy boulders (large mass of the walls) and seal all the gaps (good seals in the doors), the water – which, in our analogy, is sound – will remain on the other side. However, if there is even a small hole in the dam, the water under pressure will burst through it with immense force. In acoustics, this works identically: sound behaves like a liquid that will find any, even the smallest, crack to get in or out, nullifying the soundproofing effect.

Summary

The acoustic insulation of a cabin is a key parameter that guarantees the privacy of conversations (so-called speech privacy) and protects the user from external noise. A high value of this parameter (e.g., speech reduction of 30 dB) indicates an advanced construction that effectively blocks the flow of sound waves, in contrast to acoustic adaptation, which only ensures that there is no echo inside the room.