How to get your money's worth when buying sound absorbers. - The key factors to consider

How to get your money's worth when buying sound absorbers. - The key factors to consider

Let's face it. You probably know nothing about sound absorbers, right? So what should you look for when buying them? It's not like you can try them on. How can you be sure you're getting quality absorbers that will work in your space? Well, if you have no idea of what matters when buying sound absorbers, this is for you. 



The secret to getting rid of the echo is to first choose the sound absorber, and then figure out how many you need. That´s because how many you need, depends on how effective the sound absorber is. If the absorber is very efficient it can absorb around 85-95% of all sound that hits it. That means that you can get away with covering a smaller area than if you use a less efficient sound absorber. 

All soft materials absorb sound, but some better than others

Soft materials like textiles and pillows dampen sound. How well they perform depends on aspects like the material properties, weight, thickness and shape. Curtains for example can be made off a very sound absorbent material, but they are usually quite thin which limits the effect. When buying sound absorbers you should look for products that have been certified by an acoustic lab, to make sure you know the performance of the product. 

“But how do I know how efficient a sound absorber is?”

The absorption coefficient tells you how much sound is absorbed. 

To evaluate the performance of a sound absorber it is tested  in a reverberation room. The room has known and standardised properties so one can calculate how much sound the product has absorbed. The absorption coefficient is a number between 0 and 1.  If α=0, that means the product absorbs no sound and is a perfect reflector. If α=1 on the other hand, then all the sound has been absorbed and the product is a super absorber.

A sound absorber will perform differently for different frequencies.

It’s important to know that a sound absorber will dampen high frequencies and low frequencies differently.  For example a curtain can dampen high frequency sounds well, like birds chirping ,while lower frequency sounds, like human speech, are unaffected. 
A quality sound absorber will dampen sounds well in a broad frequency range. That’s why you should be looking for a graph that tells you how well the product dampens different frequencies.
Here is an example of the absorption coefficient for a curtin called Drops Acoustic, by Kvadrat. 
Sound absorption coefficient for Drops Acoustic Curtain:


This curtain is developed with acoustics in mind, and for a curtain it performs very well, an excellent choice if you have a lot of large windows. To show the difference between a curtain and a sound absorber, let's look at the performance of Basic Wall in comparison.
Sound absorption coefficient for Basic Wall vs Drops Acoustic Curtain:


The difference is obvious. It's important to notice the difference especially in the mid range from 250-2000 Hz. This is a range that is difficult to dampen, and also it's an important range for the human voice. At 500 Hz Basic Wall has an α=0,88, which means that 88% of the sound waves with a frequency of 500 Hz are absorbed. In comparison the acoustic curtain absorbs 38% of these sound waves. Considerably less than Basic Wall. 

Weighted values - Absorption factor and NRC

To quickly assess a sound absorber you can also look for a single number called NRC or 𝜶w . These are weighted averages of the sound absorption coefficient from low to high frequencies. The NRC is more commonly used in the US, while the 𝜶w is used within Europe. 
Both are numbers between 0-1, where 0 means that the product absorbs no sound, and 1 means the product absorbs all sound of all frequencies. Generally you should avoid sound absorbers with an NRC below 0.7. 

“What else should I consider?"

Looks for one thing..

Well, most of us care about what our space looks like, so aesthetics is actually quite important. If you can’t find products you actually like chances are you’ll leave your walls bare to keep your minimalist style, thinking you’ll just have to live with the echo. So how’s that working for you? Since you’re reading this I would say the echo is bothering you enough by now, and you should definitely get rid of it. 
Designing sound absorbers that both work well and look good is not an easy task. That’s why we challenged star designers Vera & Kyte to twinkle their design magic on our Felt Tiles. Thanks to them, you can now reduce echo with a truly elegant wall piece. 
Felt Tile Patch in Really - wool slate 


The wellbeing of planet earth

Needless to say you should give some thought to what the absorber is made from, and whether it’s a healthy one for the environment. We believe the future should be circular, which is why we work with materials like Really, that is made up of recycled textile scraps. It’s also designed to be recycled again and again. 


“So when I have found a sound absorber I like, how do I know how many I need?”

Good question, but finding the answer is not that simple. How many sound absorbers you need depends on the size, shape, materials and interior style of your space. The first thing you need to know is how much echo (or reverberation) there is in your space. You need to know the current reverberation time, the volume of the room, your desired reverberation time, and the absorption factor of the sound absorber, in order to calculate how many you need. 
Ouch! That was a long geeky sentence. Sorry about that! But no need to panic. You shouldn't have to guess and risk using too few absorbers. Or worse, dampen too much, meaning you've spent more money than needed. To make sure you succeed we'll help you figure out exactly what your space needs. 
By analysing the sound of a balloon pop or clap, we can find out just about how much echo there is in your space. And if you fill us in on details like the size and shape of your space we can help calculate how many sound absorbers you need. We can also suggest products and point out the best spots to place them. And the best part is, we’ll do this for you for free, with no strings attached. So if you haven't already, go ahead and get your free room evaluation! You can only get wiser.


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