By Shaun Snaith
Acoustic Treatment Overview for Dummies
Is soundproofing the same as acoustic treatment?
Acoustic treatment products treat the room the absorbing materials are placed in. The materials treat the room by reducing reverberation, echo and standing waves etc. Absorbing materials such as acoustic foam and mineral wool do not stop sound from leaking out of the room.
Acoustic tiles, for example, will cut down the ‘liveness’ of the room making it more suitable for performing music, recording music and even listening to music.
Soundproofing is the isolating of the room from its outside world. It also reduces sound leakage between rooms. So, for example, if you have two recording rooms together you will need sound proofing to reduce Studio A being affected by Studio B.
Acoustic foam and mineral wool will improve room isolation but only very slightly. To be able to sound proof properly involves a lot of work and a lot of cost. To gain perfect sound isolation you ideally need to build a room inside a room.
This can be very expensive but there are some cheap and easy solutions that can improve sound isolation and reduce sound leakage. First it is a good idea to totally seal doors and windows, as this is where most sound transmission occurs. Of course if this is done the installation of a ventilation unit is necessary. Another solution is to turn down the levels!
The purpose of acoustic foam is to reduce reverberation time and to generally improve the acoustics of the room. By installing products such as acoustic tiles and bass traps, recordings are defined and tight instead of having way too much color in and out of the control room.
Acoustic treatment is also needed in a room where mixing is going to take place. If the room has too much echo and too long a reverberation time mixes will be out of time and poorly judged.
However, too much acoustic treatment can be installed. This can result in unnatural recordings. The results will show a lack of color and can create a very difficult room to work in.
This is why we never treat a room with total acoustic foam. We work on percentages. We start with the minimum and keep adding little by little until we get the perfect sound or the sound the client is trying to acquire.
By leaving some of the walls and ceilings bare there are still some reflective surfaces, which helps to keep the room a little bit live. Every room is different and every room takes a lot of planning and forethought. The construction of a room, its width in proportion to its length and height all has a bearing on how the room sounds and the amount of acoustic treatment that is necessary.
When it comes to treating a room that is going to be used for recording music it is not just a case of sticking foam you bought from the local upholsterers and sticking it here and there. Acoustic foam has properties that differentiate it from any other type of foam.
The cell structure and make up of acoustic foam is very different from upholstery foam. While it will have some positive effect on how the room sounds, upholstery foam will never be able to treat a room in a way that specially produced acoustic foam can. And while duvets and curtains will only treat high frequencies, acoustic foam will treat the mid and low-end frequencies too.
When a person does the hand clap test in a room they are only hearing the reverberation of high frequencies. If they have installed upholstery foam a person could come to the conclusion that their room is fine acoustically.
However, if they were to test the room for its mid and low-frequency responses a totally different result will be exposed.
So what’s the answer?
Professional acoustic foam and professional room analysis.
How Much Acoustic Treatment Should I Use?
This is a very difficult subject to address. This is because every room is different. There are also a lot of factors to take into consideration. Here is a list of a few contributing aspects;
o The size of the room has a direct relationship to the acoustics of the room.
o The construction of the room can affect the way certain frequencies are heard.
o The use of the room determines how much treatment and of what sort is necessary.
o The style of music influences what acoustic treatment has to be installed, whether it be mainly bass trapping or mid to high frequency absorption.
o What, if any, furniture is already in the room and its absorbing properties.
o How much space there is available on the walls and ceiling for acoustic treatment controls which products would need to be used.
As a generalization most rooms will need between 25% and 75% of coverage. This is only for the walls and ceiling. Most people forget that the ceiling is just as important when it comes to treating a room as the walls are.
Here is a brief overview of suggested quantities of acoustic treatment:
o Control Rooms for rock, pop, rap, hip-hop, R&B, country, techno, MIDI music, etc. usually benefit from 50% to 75% coverage and mostly absorption. Bass Trapping is also an important part of acoustic treatment for this type of room.
o Control Rooms for jazz, art (classical), choral, acoustic, world and other forms of ensemble music usually benefit from 35% to 50% coverage.
o Mixing rooms usually call for quite a dead area around the mixing desk itself from 50% to 85%. Around the rest of the room it needs a little absorption between 20% and 40% along with some diffusion.
o “Live Rooms” will vary a lot. Some well-designed live rooms can get by with 20% coverage (or even less!). Most fall into the 25% to 50% range. The most successful Live Rooms usually have some degree of variability. This is done so that a studio is not limited to a certain number of styles of music. By making the room adjustable it gives the studio a high ability to accommodate different styles of music. This can be done by using our Sound Trap Panels.
o Isolation Booths usually call for quite a bit of absorption – 75% or more. If the booth is to be used for very tight vocal booth then near 100% absorption may be necessary.
o Home theaters and dedicated listening rooms do require quite a large area of absorbing foam on the walls. This is mixed with some diffusion on the ceiling also.
Almost never will 100% absorption be needed and neither is it suggested. The room, no matter what it is going to be used for will still need some ‘liveness’ in it.
If 100% absorption is used the room will feel very close, tight and very unnatural. The room could come to feel quite claustrophobic and extremely difficult to work in.
By leaving a percentage of the area of the walls bare the exposed part can be reflective thus helping to stop your recordings or practice sessions from being overbearing. This will have the outcome of much better performances and recording results.
As we said earlier, every room is different and every room needs its own analysis to work out the correct percentage of acoustic treatment. If it is calculated incorrectly the room will never sound right and will not give your work the justice it is due.
That is why we suggest you get a professional room analysis and consultation.
Why Do I Need Acoustic Foam?
Acoustic foam is probably the most important aspect of any studio, home theater, or dedicated listening room. It can either make or break a professional studio project. It doesn’t matter how much is spent on recording and monitoring equipment. If the room itself is not treated to its optimum the results will never be as good as they should be.
Usually the room in which the customer plans to record or perform in is not specifically built with acoustics in mind. If this is the case then acoustic treatment is all the more important. Rooms have their own sound already within them. While the sound is traveling around the room it will come into contact with different surfaces and other sound waves moving around the room. This means that the room can suffer from a lot of acoustic problems.
These could include reflections, reverberation, slap echo, flutter echo, inadequate frequency response, standing waves and modal problems.
While all these frequencies are bouncing around, clashing into each other the sound waves can change. This totally affects the end result negatively. You will start off with one sound and end up with another in the recordings.
Until recently acoustic foam was not taken seriously. This has resulted in a believing that acoustic treatment is not necessary and just a waste of time and money. In fact the opposite is the case. Spending your full budget on equipment and none on acoustic treatment will seriously deprive your room of proper acoustics.
If no acoustic treatment is installed in the studio the reverberation can be so long that practice sessions can be a chore and not a pleasure. Recording will be difficult to control and mixing will be difficult to master. When recording or trying to monitor a recording you want to take the room out of the mix, it needs to be controlled.
What you really want and need to hear is the source, whether you are recording or monitoring. What you don’t want is the room telling you what to hear and what to record. Imagine the room as a big instrument. If that instrument is not tuned correctly you will only hear an out of tune room. Not a room that works in harmony with the recording or sound.
A room without acoustic treatment will be very reflective. If there are no surfaces in the room where sound waves are absorbed then the result of the recordings will be out of control. By installing acoustic foam the ‘liveness’ of the room can be brought under control and the response of the room can be improved.
Use of acoustic treatment is the only way you can tell if what you are recording, editing, mixing or monitoring is accurate or not affected by the room you are in. Acoustic Treatment gives you the added ability to record and monitor accurately. Whether you want the room live or dead, acoustic treatment is the only way to tame the beast that is your room and keep it under control.
An added benefit of installing acoustic treatment is that the environment you are working in will be improved. You will find yourself in a place that is easier to work in and you will also find yourself more comfortable. This in turn will improve your productivity, creativity and you will gain more enjoyment out of your room.
Acoustic foam is so easy to work with too. It is easy to cut, to size and trim. And it can be a very cost-effective way of treating your room. Acoustic foam will reduce the pick up of loose frequencies when recording making the recording and monitoring process much cleaner and defined. This results in more accurate recordings and allows you to hear exactly what is intended to be recorded without the room having an unfavorable effect of the end result.
Why Do I Need Bass Traps?
Standard acoustic tiles are only truly effective at mid to high frequencies. This is because the tiles are thin and can only absorb shorter waves. Or absorb waves with less power that are traveling at slower speeds. This means if only acoustic tiles are installed there is not enough foam to be able to absorb the stronger more powerful waves.
Low-end frequencies have very long wavelengths. These wavelengths have a lot of strength. This means that more foam is necessary to absorb these frequencies. This is why bass traps are absolutely required in any room that is going to be used for recording, mixing or practicing.
The frequencies tend to build up in the corners of a room and this is why we have corner bass traps. Most studios do not have the space or funds available to be able to treat the whole wall with thick, bass trapping foam. And you wouldn’t want to do that.
Sound can be 6dB louder in a corner than in any part of a room and this is why we insist on the installation of bass traps in the corners. The wider the bass traps the lower they can absorb. Standard bass traps are usually 12″ wide but these bass traps can’t absorb the very low frequencies. This is why we companies such as Advanced Acoustics have introduced the MAXXX Bass Trap. This has a width of 24″ creating a larger area for the low and very low frequencies to be trapped.
Bass traps do not just absorb the low-end frequencies in your room. They also help to better define the low frequencies making them easier to control and recognize. This in turn helps you to achieve better results in your recordings. If a person is having trouble with the music sounding good in the studio but terrible in another room he or she needs bass traps. The situation just mentioned is a common problem and can easily be solved with the use of bass traps. These are not expensive and it is not necessary to fill a room with them. With correct installation in the right places low-end frequencies are tightened and excessive coloration is removed.
There are two types of bass traps. There is the foam bass trap constructed from solid high density acoustic foam specifically designed to absorb those hard to deal with low frequencies. There is also the Mineral Wool Bass Trap. These are good at absorbing low and very low. The bigger the bass trap the better it can perform and the better the response of the room.
Does The Profile Of The Foam Make A Difference?
In a word, yes, it certainly does. Plain faced foam and profiled foam both have their pros and cons.
First, let us discuss plain faced. Because the foam has no profile the absorption properties of the foam is much greater compared to profiled foam. This is because there is no foam removed from the tile resulting in more foam per square meter or square foot when compared to profiled acoustic tiles of the same peak thickness.
The more foam there is to absorb the frequencies the better the results you are going to receive. And, so the opposite is true of profiled foam, the more complicated the profile the worse the performance will be. This will mean that either thicker tiles will need to be installed if the room has poor acoustics.
If the room has reasonably good acoustics then the thinner tiles will do fine along with some bass trapping. Think of the acoustic foam as a sponge. Take a piece of foam that is 2″ thick and has no shape to it but is just a slab of foam. That piece of foam is going to be able to soak up more water than a piece of foam that has valleys and troughs in it.
Acoustic tiles that have no foam removed from the face of the foam also show a much better performance at low frequencies than profiled foam. This obviously depends on the thickness of the foam but generally this is the case.
Low frequencies have longer and stronger wavelengths. This means that it takes more foam to be able to absorb those low frequencies. With profiled tiles there simply just isn’t the foam there to be able to absorb those lower, stronger frequencies. Thinking back to the sponge and water example, if you fired a jet of water at the plain faced foam less water would leak through the back as opposed to profiled foam.
There is however a few down sides to plain faced acoustic foam. Sound hitting the foam, especially at shallow angles could have a tendency to glace the foam and be reflected back without much absorption. Granted this is rare as most of the sound waves hitting the foam would be more direct if the foam is placed in the correct place.
If the foam is not installed in the right place the acoustic foam will not be able to work to its full ability. This is why it is recommended that you discuss the room you plan on treating with professionals so that they can direct you in the right direction as to where to best to install the foam.
One other little nuisance in plain faced acoustic foam is that it is not always aesthetically pleasing for some. But every person has their own taste. This is one of the reasons why there is such a wide range of different profiled foams. Whether you require a contemporary look, a modern look or a clean and crisp look, hopefully there will be something that would appeal to your taste.
It is not all bad for profiled acoustic tiles. While we said that sound waves can have a tendency to bounce off the plain faced tile at shallow angles, profiled foam can catch or trap the sound waves striking it. This will reduce reflections in the room. It will tighten up those high to mid frequencies and create a room that has much better response and control. Of course the room will require bass trapping to be able to cope with the low frequencies. Those sound waves which are more difficult to treat and absorb.
Another good thing about the profiled tiles is their good looks. They help to break up the plain-looking walls to add another dimension to the room when it comes to looks. An inspiring looking room will, we are sure, translate into inspired music and performances.
In the end there is always a product that suits every situation. Whether you need a lot of absorption, need to just tighten up the response of the room a little or cut down the reflectivity of the room we have a product that will suit your needs both acoustically and visually.
The best solution, of course, is a combination of both plain faced tiles and profiled tiles. And at Advanced Acoustics they have been able to deliver exactly what is required. A range they call the Euphonic is a pack of tiles which is made up of both 2″ thick plain faced tiles and either convoluted foam tiles or wedge profiled tiles.
A great compromise and great aesthetics.
Article Source: http://EzineArticles.com/expert/Shaun_Snaith/49042