THEsound absorption of materials it can be complex in work environments, commercial establishments or domestic spaces.
In indoor environments where we spend our daily lives, sound waves shouldn't make communication difficult. But when the sound absorption of coatings and furnishings is not good, it is easy to find noisy places where there is a strong sound reverberation.
How to do in these cases?
First, you need to understand what the sound absorption of materials and why it matters. Then we need to evaluate how to increase it to improve the experience of all the people who visit the space in question, whether it's a home, an office or a shop. In this article, you will find all the essential information you need to know about sound absorption of materials.
What is sound absorption of materials
To understand what acoustic absorption of materials is, also called "sound absorption", it is good to recall the notion of acoustic wave.
A wave is defined as one disturbance which spreads in space carrying the energy from a point A to a point B through the variation of a physical dimension.
In the case of sound waves, the physical quantity subjected to variation is a property of the medium in which the waves mostly propagate, i.e. a property of the air: the pressure.
Il sound absorption corresponds to the ability of a given material to absorb the energy carried by the sound wave.
The greater the sound absorption a material is capable of, the lower the sound reverberation and improve the acoustics of the room.
The sound absorption coefficient
When an acoustic wave hits a surface, part of its energy is absorbed and part, on the contrary, “rebounds” and propagates back into the environment. This reflection of the sound wave is called "acoustic reverb".
The reflected acoustic wave that propagates back in space interferes with the waves that spread from the initial sound source. So you create a echo effect annoying and the environment is noisy and unpleasant for those who spend time there.
Il sound absorption coefficient quantifies the ability of a certain material to absorb sound wave energy.
It is indicated with the letter of the Greek alphabet α (alpha) and can be found in tables which give the measure corresponding to the different materials.
If the acoustic coefficient is 0,86, for example, the material to which it corresponds reflects 86% of the energy of the sound wave.
Why is the sound absorption coefficient of materials important
The acoustic coefficient is an important data because it allows us to get an idea of how a material will behave acoustically in a closed environment.
The measurement of the acoustic coefficients allows us to distinguish between sound absorbing materials and non-sound absorbing.
There are five classes of sound absorption which are identified by uppercase alphabetical letters, from A to E.
Sound absorption class A corresponds to those materials which have a coefficient between 0,90 and 0,95 and are therefore very absorbent.
Conversely, the last class, E, includes materials that have a coefficient between 0,15 and 0,25.
If the coefficient is between 0 and 0,10, the material is considered reflective and therefore not classifiable in terms of sound absorption.
The sound absorption coefficient comes into play in calculation of the reverberation time, which is inversely proportional to the ability of a material to absorb sound waves.
Calculation of sound absorption
To understand how much the acoustic reverberation affects in an enclosed space, causing an annoying echo effect or ensuring a good perception of sounds, it is necessary to calculate the reverberation time.
The calculation is carried out through the so-called “Sabine method".
Reverberation time is measured and generally indicated as T60, i.e. the time required to reduce a sound by 60 dB. To quantify T60, Sabine's formula is used: T60 = 0,16*V/A
The variable V corresponds to the volume of the environment, whose reverberation time is being evaluated, which must be expressed in cubic metres.
The unit of absorption
On the other hand, the variable A is more complex, which corresponds to the absorption unit and is obtained as follows: A = Σ S*α
S is the surface area measured in square metres, while α is the acoustic coefficient. S and α are measured for each surface of the room: floor, ceiling and walls.
How to increase sound absorption
Sound absorption is greater in those porous materials which, due to their conformation, are able to "trap" the sound wave.
If at home or in the office or in your business, there is a consistent acoustic reverberation that disturbs communication, you need to think about how to increase sound absorption. One possibility is to include many textile elements, even draped ones. Velvet, wool and fabrics that have a textured surface offer good sound absorption.
A more effective solution is represented by sound-absorbing panels, specifically built to retain the energy of sound waves, minimizing interference with the original sources.
The panels to improve the sound absorption of materials
we at Momenti offer Acoustic Wall Sound, a system of decorative sound absorbing panels which ensures the purity of the sound and the beauty of the whole.
The material is specially made to retain sound waves inside the tiny cavities that make its surface porous.
It is covered with art prints that reproduce the work of established designers of the highest caliber. Thus the acoustics of your restaurant, your home or your office are the result of the union between creative intuition and research excellence in the materials sector.
