In the hustle and bustle of modern life, silence has become a precious and rare luxury. We are immersed in a constant din, in a harmony of noises that invades our sensory sphere and distances us from ourselves. But what happens when silence can be recreated in an environment where we seek inner stillness and sound harmony in the spaces around us?
We often mention two concepts in our blog that are fundamental for ensuring the well-being and comfort of interior spaces: these are sound absorption and sound insulation. The uninitiated might confuse these two terms, which aim at a single goal, albeit with many differences: a home’s or office’s acoustic well-being.
In this article, we will delve into the world of sound absorption and sound insulation, exploring their nuances and their importance in creating environments that provide peace and comfort.
Sound absorption: what it means
Sound absorption can be defined as the art of embracing sound, capturing it and making it soft and warm. It is the ability of a material or surface to absorb sound waves.
This seemingly simple concept conceals complexity. Sound absorption requires a deep understanding of sound and its characteristics and mastery of the art of selecting and using the appropriate materials.
Sound takes on a new dimension when a room is equipped with sound-absorbing materials. Sound waves find an anchor of stability and are transformed into a harmonic flow, an enveloping sensory experience. Voices spread naturally, noises are attenuated, and a space is created in which one can feel at ease.
Reverberation time, a fundamental concept in sound absorption
The absorption of sound waves in a room by a sound-absorbing material reduces reverberation time. We have already mentioned this concept in our blog, but we will take it up again because it is fundamental to understanding how to make a room more comfortable in terms of sound.
The reverberation time refers to the time for the sound pressure level to attenuate by 60 dB after the sound source has stopped. In other words, it represents the time it takes for the sound to decrease in intensity within a room.
Sabine’s formula gives the standard formula for calculating the reverberation time of a room:
T = (0.161 x V) / A
Where T is the reverberation time in seconds, V is the volume of the room in cubic metres, and A is the total area of sound-absorbing surfaces in the room in square metres.
This is an important parameter because, if too long, it can cause excessive reverberation, making it difficult to understand speech, create a noisy environment or make it uncomfortable to perform certain activities. Conversely, too short a reverberation time can result in an environment that is too dry or lacking in desired resonances, which may be acoustically unpleasant.
Using suitable sound-absorbing materials can adjust the reverberation time to achieve an acoustically balanced and comfortable environment.
Sound insulation: what it means
On the other side of the coin, there is sound insulation.
This concept refers to the set of techniques and materials designed to reduce or limit sound transmission from one environment to another. It is the art of creating a protective barrier that prevents noise from invading a space, thus preserving the tranquillity and well-being of the people living in it.
Sound insulation is based on physical and engineering principles, using special materials and targeted construction techniques to minimise sound propagation through walls, floors, ceilings and other surfaces. It is a process that requires in-depth analysis of sound characteristics and how it is transmitted to select and implement the most effective solutions.
So what is the difference between sound insulation and sound absorption? Mainly the objectives.
Sound insulation aims to create a protected space in which external noise is attenuated or completely eliminated, allowing people to enjoy a quiet and comfortable environment. In contrast, sound absorption aims to reduce or control the echo and reverberation of sound within a room, creating an acoustically comfortable environment optimised for communication and listening.
Are the materials used for acoustic insulation and sound absorption the same?
Given the differences in the goals of sound absorption and insulation, the materials also change considerably.
Acoustic insulation materials are designed to reduce sound transmission through a room’s walls, floors and ceilings. Sound insulation’s main goal is to limit sound propagation from one room to another, so materials that achieve this goal have a thick, dense structure.
Among these, the most widely used are stone wool, which consists of thin fibres obtained by melting volcanic or basaltic rocks at very high temperatures; acoustic foam, a lightweight, porous material that is used for acoustic insulation in environments such as recording studios, rehearsal rooms and theatres; and wood fibre, another common option for improving room acoustic insulation.
On the other hand, sound-absorbing materials are designed to reduce echo and reverberation within a room itself. These materials are able to absorb part of the incident sound, thanks to their porosity and a cell structure that retains the sound and does not allow it to ‘bounce’ within the environment.
Among the most widely used is polyurethane foam. This versatile material can be used in various applications, such as conference rooms, restaurants, recording studios and home environments, or even our high-performance and efficient cork.
Conclusions
Understanding the differences between sound insulation and sound absorption is of fundamental importance for designing and realising acoustically optimal environments.
This is demonstrated by Diasen’s sound insulation and also by the sound absorption intervention at the Campo das Cebolas underground car park in Lisbon.
Here, an acoustic insulation and reverberation reduction intervention was carried out using Diathonite Acoustix cork-based thermo-acoustic biomalta. The solution was applied to the ceilings of the structure, with a thickness of 3 cm distributed in two layers of 1.5 cm each, together with Polites 140 structural reinforcement mesh.
This choice made it possible to combine acoustic effectiveness with an aesthetic that favours an almost smooth finish. Argatherm Acoustix acoustic skim coat was used to ensure a fine and uniform grain size, allowing the system to maintain high acoustic performance due to its microporosity.
Discover all Diasen products, biomalta, plasters and cork-based paints, ideal for thermal and acoustic insulation of environments. Find well-being and comfort in your environments, thanks to the naturalness of our products. Contact us for more information.
