Acoustic foam does work and will improve the sound quality of your home recordings if the correct type of foam is chosen and positioned in the optimum position within a room. As there is not a “one size fits all” approach, acoustic foam often gets a bad reputation in online discussions as results will vary between studios.
What is acoustic foam and what is its purpose?
If you’re looking to acoustically treat your home recording studio or office studio, acoustic foam can be an affordable and good solution.
Acoustic treatment is the process of using various materials to improve the internal room acoustics of a recording or listening space.
Sound travels in waves and as you listen to or record music, sound is constantly bouncing off the internal walls of your studio, reflecting off surfaces and interfering with each other.
Sometimes, these internal sound wave reflections can interfere with each other and create problems for content creators.
When mixing audio and trying to ensure that your content sounds good, as a producer it is hard to know if you’re hearing the true sound of your recording or if you’re hearing an effect of your room acoustics and internal sound reflection.
It could happen that you might mix your content in a recording studio and it sounds great, however you then take your recording to another room and it is completely different or doesn’t sound too good at all!
Therefore, you will want your home recording studio to be as acoustically neutral as possible. In a perfect world you should want the sound in your recording studio to be as accurate to the original recording as possible without any interference or influence from the acoustics in your room.
What is acoustic foam used for?
Standard “off the shelf” acoustic foam is typically good for treating the mid to high frequencies in a room if positioned well.
Acoustic foam is typically very cheap and easy to work with. It is possible to carefully position acoustic foam in your room to absorb mid to high frequencies and help create a neutral listening environment.
Acoustic foam can be simply glued to the walls of your studio or if you don’t want a permanent solution, you can glue foam panels to some board and hang it just like a picture.
In addition acoustic foam is very easy to cut so it’s quite easy to make custom shaped pieces for your studio
There are many different types of acoustic foam on the market. Typically, the thicker the foam the more sound lower frequencies that will absorb.
You will find that most acoustic foam that you buy off the shelf will have sculpted pyramids or wedges on its front face.
As well as looking cool, the function of these wedges is to provide greater absorption of frequencies. In a nutshell, when sound hits the foam at an angle, it has more thickness to pass through and therefore, you will get greater sound absorption.
Often acoustic foam has a bad reputation particularly in internet discussions and online.
Complex mathematics and physics is used to carefully position acoustic foam, however, as every room varies in shape and size, there is not a “one size fits all” solution, so acoustic treatment is often seen as an art form more than a science.
This can cause conflict between acoustic engineers, as some engineers can get great benefit from acoustic foam and others will fail to see the effect.
At the end of the day it’s all about placing your acoustic foam in the best position to absorb stray mid to high frequencies. Do that well and your acoustic foam will help.
How do you compare acoustic foam materials and products?
There are so many different types of acoustic foam on the market, with different shapes and sizes, that it can be very difficult to compare and contrast acoustic foam.
One figure that exists to compare acoustic products is called the “”Noise Reduction Coefficient” or NRC for short.
This number shows the overall performance of the acoustic material.
Basically a manufacturer will measure the reverberation room response, then add some acoustic foam, and measure how much reverb is present in the room after the acoustic foam has been added.
Then using some fancy maths an absorption value is calculated and rounded off to the nearest number.
This now gives us a number which tells us how well the material performed which can be used to compare different acoustic products.
This NRC number is great for indicating overall performance.
If you have a specific frequency that you want to absorb, then you’re better off looking at the acoustic coefficients, which shows the absorbent qualities of a specific material for a different frequency band.
At the end of the day, all this information is just data that can help you make a better decision.
Other factors that will influence your acoustic foam shopping decision will be:
1 – how easy it is to work with
2 – how good does it look
3 – how easy it is to mount onto your walls
Most cheaper or generic acoustic foam will not have data included.
When picking cheaper foam you will just be provided with overall dimensions, including thickness. The thicker the better.
If you want to get more technical with your acoustic foam selection, the best people to talk to are the manufacturers as they will know their products and will have tested how well their foam performs.
I recommend “Auralex Acoustics” as they specialise in acoustic foam products, have fantastic technical data and always produce great quality products.
Will any foam work?
In theory any form or soft surface will act as an acoustic absorber.
To save money, many creators have used foam mattresses, dense packing or foam pillows to try and acoustically treat the room.
As mentioned, any soft material will absorb high frequencies, so in theory these alternatives will work, however, they don’t compare to the performance of specifically designed acoustic foam.
True acoustic foam, such as the solutions offered by Auralex Acoustics, are shaped and designed for optimum or specific acoustic performance.
In addition, true acoustic foam is made from an open cell material. “Open cell” means that there are holes in the material that allows sound energy to easily pass through – when sound passes through the material it is absorbed.
Where should I place acoustic foam?
In order to get the most out of your acoustic foam, where you position it in your studio is essential.
I’m afraid that just purchasing acoustic foam and sticking it on the wall will not be effective, unless you get really lucky and accidentally stick it in the right place!
Acoustic treatment is considered more of an art than a science, however there are some basic rules you can follow to help you place your acoustic foam in a good location.
Typically acoustic foam is used to absorb high frequencies and should be positioned at the first reflection point in relation to your studio monitors,
There is an easy method you can use to find the first reflection point.
Ensure your studio monitors are in their permanent position and sit in front of your monitors in your usual listening position – just as if you’re going to work in your studio for the day.
For the next part you gonna need an assistant…
While sitting in your listening position, ask your assistant to hold a mirror against the wall on your left, roughly centred between your listening position and the speakers.
Here is an image to demonstrate.
Now ask your assistant to move the mirror along the wall until you can see the nearest studio monitor reflected in the glass – this location is your point of first reflection. Your acoustic foam should be placed at this point.
Repeat this procedure for both monitors, then do the same for the right wall.
Here is a video to show the method.
As well as adding acoustic treatment to the side walls of your studio it’s also a good idea to add acoustic treatment to the wall behind you.
An acoustic diffuser or acoustic foam with a particularly jagged face is useful here.
In addition place some acoustic foam on the wall behind your studio speakers.By treating the wall behind your studio speakers, you will improve reflections and imaging of sound waves hitting off the back wall at the rear of your speakers.
“Off-the-shelf” acoustic foam is typically very good for absorbing mid to high frequencies but if you want to absorb and deal with lower frequencies you can use double layers of foam to increase the absorption thickness.
Alternatively you could mount foam panels with an air gap between them.
By adding an air gap between your acoustic panels and foam sheets, you will create a better absorption result and absorb more lower frequencies.
Acoustic foam does work in treating acoustic home recording studios and listening rooms as it improves sound propagation problems such as internal room reflections and standing waves.
The key is to choose your foam carefully and position it in the optimum position to absorb sound.
Finding the best position to locate your acoustic form can be really difficult and many experts will have varying opinions on this, so if you are new to the field of room acoustics, just jump in, experiment and have fun.☺️