You must have heard of soundproof rooms or acoustic treatment in various places—in hotels, in offices, in newsrooms or music-recording studios.
Have you ever wondered what all goes into making a space soundproof?
Well, a lot! But, before that, let us exactly clarify what soundproofing exactly entails. In this article, we will also dispel some misconceptions about what soundproofing does, and correct some basic concepts.
If you are looking to polish your knowledge about sound treatment of rooms or looking to get started on having a soundproof room constructed, read this article till the very end. It will acquaint you with details you never knew existed. You’ll thank us later. So, without wasting another moment, let us get started.
Few Basics about Sound
Yes, everyone knows what sound is. But to understand how we deal with it, we need to understand some basic properties of sound. Let us take a quick look back at those old science lessons from our school books.
Sound exists in the form of invisible waves that travel through all three states—gases, liquids, and solids. It can emerge in two manners. One is by being carried via air, such as blaring horns or the sound of music; this is known as airborne sound. The second is created by the striking or collision of two solid objects, such as a hammer hitting a nail or something as simple as a clap. The second kind is referred to as sound that is borne out of impact.
Now that you know the two factors above, you will realize that sound travels pretty much everywhere. This is why we hear the honks from the traffic blaring from the street outside as much as we hear the clickity-clack of the keyboard keys.
You must now also be wondering that if sound travels in such a manner, do measures like soundproofing even work?
That’s something we are going to look at in the following section. Read on!
What Is Soundproofing
Soundproofing is the technique of reducing the pressure put by sound waves. This technique can be aimed at reducing the sound pressure created by the sound source. Alternatively, it can be aimed at reducing the pressure being created by the sound waves on the receptor.
In simpler words, soundproofing is a means of reducing sound from a particular chosen space or environment. These means or techniques are also referred to as acoustic treatments. These are developed to suppress, reflect, diffuse or absorb the sound waves either at the source of the sound or its destination.
There are three primary techniques via which soundproofing takes place. Here is a brief look at these three techniques.
Absorption of sound is one of the most commonly known methods of soundproofing. You must have seen the walls of an auditorium covered with a material that looks like a heavy fabric. That is done to absorb the external sounds and to prevent echoes as well. Absorption works by converting sound waves to tiny amounts of heat which are converted and preserved in the absorption materials installed in the soundproofed space or room.
This technique can be done by installing the following types of materials:
- Sound absorbing tiles
- Sound absorbing panel
- Absorption foam
- Heavy fabrics meant for acoustic absorption
- Heavy blankets
This is another way of tricking those sound waves to stop creating noise beyond your soundproof enclosure. The method of diffusion works by breaking down the sound waves into smaller paths and scattering them in various directions. Therefore, on colliding with a diffusing surface, the shorter, broken-down sound waves lose their energy. They are not able to complete the path and this deters them from creating large pockets of noise within the room.
The method of reflection for soundproofing a space is usually used in outdoor settings. The reflection of sound waves depends on the surface on which the waves fall. There are two ways in which reflection can happen. This depends upon the purpose and the external space.
- Usually, in open, high-noise areas like highways, the engineering of sound reflection is such that the sound waves are directed upwards towards the sky. In a way, it acts like a vent to all the noise generated by the vehicles on the highway.
- On the other hand, in other external environments like the exterior of a high-rise building, the use of the material and its engineering is different. Here, the sound waves are directed away from the building by using reflective surfaces on the exterior of the building.
Targeting the Source
Usually, when we think about soundproofing, we tend to think more about all the noise that comes from the outside — blaring honks and engine noise from the traffic on the nearby street, chirping of birds, a neighbor who cannot seem to party without loud music, or some construction work going on nearby. The list is endless. But do you think that’s the only noise disturbing you?
The answer to the above question is ‘no’! There are two categories of soundproofing depending on the different sources from where noise is generated.
- External Sources of Noise: The soundproofing methods discussed above are largely used to tackle noise generated by external sources. It might be noise coming from outside the building, such as traffic or construction noise. It might even be noise coming from neighboring rooms or the floors above and below yours. In this case, the measures taken to inhibit the noise is directed towards external influences.
- Internal Sources of Noise: This category will be best understood if you are working in a studio or any room with multiple, heavy-duty computers. The buzz and other similar sounds created by these machines within the room have the ability to hamper any recording significantly. Even apart from the technical issues like recordings, the buzzing noise of such machines creates a disturbance that the occupants of the room would like to get rid of. Similarly, the humming or rattling noise created by various kinds of air conditioning setups are an example of how internal sources of noise can be disturbing for the occupants of the enclosed space.
Do You Really Need To Acoustically Treat Your Studio?
You have the best recording equipment and microphones that cost you a lot of money.
You are now ready to start recording.
You are expecting some magnificent results because, well, you have the most amazing equipment money can buy.
Is that right? Again, no! Why you ask?
That’s because the room needs to be prepared accordingly too. Let me explain.
- When you start recording, a large chunk of the sound will go directly into the microphone.
- However, there will be residual sound that will travel in other directions in the room.
- Those sound waves will strike all the surfaces in the room and be reflected back.
- A few moments later, these reflected sound waves will also enter the microphone.
- These reflected sound waves will lead to tampering with the original sound.
Now that tampering with the original acoustics is something no one wants. So, in this section, let’s see how this can be prevented.
What Does Acoustic Treatment Do?
We spoke about absorption and diffusion techniques in the above sections. These techniques are used in interior setups for preventing noise disturbances. Especially in spaces like music studios where sound is all that matters, such technical details need to be in place to avoid poor quality output. The measures taken to ensure minimal or no noise disturbances in such spaces is referred to as sound treatment. The following few points will add more details to what is it exactly that sound treatment does.
- Ideally, a recording studio ought to be a large space that allows for excellent acoustics, let’s say someplace like a cathedral where naturally the acoustics are marvelous. But we all know that it is impossible for every studio to be like that. It is thus that techniques of indoor manipulation of sound waves exist.
- Techniques of absorption and diffusion help in this manipulation. They are used to reduce the sound waves into almost non-existent energy.
- Absorption via materials like foam walls, tiles or panels absorb the big and small disturbances created by remnant sound waves or the buzz created by the devices and machines. It absorbs all these sound waves as kinetic energy and converts them into minimal amounts of heat.
- Diffusion also aids by breaking down the large sound waves that strike the surfaces. These broken down sound waves are small and lack energy to cover longer distances.
- However, many people agree that using either of the methods does not provide absolute results. Hence, it is advised to a good combination of both techniques.
- You will find that there are a wide range of materials and devices available for providing absorption and diffusion in a studio. These can cover large areas like walls, ceilings, and floors. There are also options that prevent sounds emerging from the continuous friction of objects or surfaces in the room, or even options that help fill up air gaps.
How Is Soundproofing Different from Sound Treatment?
The terms soundproofing and sound treatment are quite commonly used interchangeably by many people. In this brief section, we will reiterate and clarify the difference between the two. But before that, here are some pointers on why you should know the difference.
- Every space, every purpose needs a different technique for noise management. When you get the work started on your soundproof restaurant or your music recording studio, you should be educated on the matter.
- Once you know the difference, you will be able to have a more productive and result-oriented discussion with the person responsible for the construction of the space.
- It will also help you make more informed decisions when you are purchasing materials or devices to aid in noise management.
Now to understand the basic difference between soundproofing and sound treatment, let us look at the following simple explanation.
- Soundproofing is all about creating barriers. You don’t like the noise? Don’t let it in. Simple as that.
- The techniques employed to achieve soundproofing are all directed towards not letting the sound waves from external sources create a pocket of noise in that particular area. The spaces that can be soundproofed can be internal spaces like hotel rooms, prayer halls, movie halls or recording studios.
- Soundproofing can also be done in external spaces like highways where the noise created by the traffic warrants such measures.
- Sound treatment is exclusively meant for eradicating the noise or disturbances in a closed space.
- The marked difference in sound treatment (vis-à-vis soundproofing) is that the source of the sound waves exist within the closed space.
- An ideal example of a space that required sound treatment is a recording studio.
- The techniques of diffusion and absorption are used in combination to achieve the eradication of sound energy.
- Sound sources like air conditioning and the buzz of machine exhausts are the target of sound treatment.
Acoustic panels are tall panels of varying shapes and sizes which are made of porous materials. They work on the principle of absorption of sound waves. You can find that not just recording studios, but places like restaurants also use acoustic panels.
Why Use Acoustic Panels
- Acoustic panels are used in large spaces like auditoriums, to decrease echo.
- They are useful in places with high frequency, a place where a lot of different sounds are being created. For instance, in a restaurant where many people talk simultaneously.
- In such places, acoustic panels absorb a large portion of noise. This enhances the intelligibility and clarity of the sound. In simpler terms, people will be able to have a better conversation.
Where to Find Acoustic Panels
There are two options:
- DIY It: You can build your own acoustic panels. For this, you can refer to online guides to understand what material to use. All you need is a trip to a hardware store and some creative talent. This will be a significantly cheaper option. But of course, it is not the most convenient option.
- Buy It: Acoustic panels can easily be found online. There is a wide variety of shapes, sizes and colors. You can find panels specifically suited to your purpose. All this option takes is to do some online browsing and research. The only drawback here is that this might be heavier on your pockets.
What Factors Should You Consider While Buying an Acoustic Panel
With the wide variety that is available in the market, you might just get confused. Or, if you simply do not know where to begin, here is a list of some factors you must look out for while purchasing acoustic panels for soundproofing.
- Noise reduction coefficient
- The standard thickness variants in which acoustic panels exist are 2 inches or 4 inches.
- Common sense would tell you that since it is about absorbing the waves, thicker should be better, but the industry standard is 2 inches.
- Why? If you remember, we earlier spoke about using a combination of absorption and diffusion techniques. So here, the 2-inch acoustic panels will absorb high to medium frequencies. For all the low frequencies, materials like bass traps can be used.
Patterns on the Surface
- There are some fancy, colorful, versatile acoustic panels available in the market.
- The usual patterns that are available are wedges or pyramids.
- Both the patterns absorb more or less the same amount of waves. There is not much of a difference in their performance on the basis of the patterns.
- You can choose either, and keep the other factors in mind.
Dimensions and Quantity
- Usually, acoustic panels come in packs or sets of multiple numbers.
- The sets you will usually find in the market are a count of 6, 12 or 24
- The standard dimensions in which these panels come are 1 sq.ft., 2 sq.ft. or 2 ft. x 4 ft.
- The most important factor here to keep in mind is the measure of the wall you will be covering. Make sure you buy a correct combination of sets and dimensions to cover the wall as per your requirements.
- For home studios, where damaging the wall is a big concern, you can even use small acoustic panels that come as decorative hangings. These do not require any adhesive installation and are safe for the walls.
Noise Reduction Coefficient (NRC)
- In products bought from the market or online stores, you can find the NRC written on the packaging.
- NRC is a coefficient between zero and one, where one is the highest noise reduction level.
- Even though this may help a little, NRC is not a self-sufficient measure to check the efficiency of a product.
As you might have read above, acoustic panels can only absorb frequencies that are high or mid-range.
For low frequencies, people depend on bass traps.
There are two kinds of bass traps. Both provide low-frequency absorption in different ways.
- Porous absorbers
- Resonant absorbers
- Porous bass traps are the first product that a person would think of when they start soundproofing. It is that common and also effective.
- They are made of materials such as acoustic foam, fiberglass or Rockwool.
- These absorbers not only work for low frequencies but have a fantastic performance across the frequency band.
- The only drawback with them is that they cannot absorb the lowest frequencies until and unless they are built extra-thick or unless they are placed far from the reflective surfaces like the wall.
- Resonant absorbers are quite opposite to porous absorbers.
- They are more specific in the sense that they do not work across the frequency band. They work to absorb the lowest frequencies.
- They work best when placed against the wall. That is when the pressure of the sound waves is the highest.
- This means good news for all those looking to save space. This means that they do not take up extra room.
- Reflection filters look like a small covering or a small booth in front of the microphone. They are placed there to provide the absorption of noise before it spreads too much. Here’s looking at some details about the types of reflection filters available in the market.
- There are heavy-duty reflection filters that use heavy porous material to provide immediate absorption of noise.
- The drawback of the above-mentioned type of reflection filters is that they need a sturdy stand to support them. This takes up too much space in the room.
- The solution to this is a lightweight reflection filter that uses the mic’s stand as its stand.
- The lightweight variant also comes at a much lower cost but is only suitable for home studios.
So you are now all set to start your soundproofing project. If you are looking for soundproofing measures for spaces like your room or a new restaurant that you are opening, you will find your answers in the details above.
If you are a music pro getting started on creating your home studio or starting the construction of a full-fledged recording studio, the above points will have your basics covered.
Before you leave, let’s do a quick revision so that you move on with the concepts fresh in your mind.
- Soundproofing is to create a barrier for noise from external sources. It can be done for enclosed spaces as well as for external spaces.
- Sound treatment is meant for managing noise generated by sources kept within the same enclosure. It focuses on reducing the kinetic energy of sound waves, thereby preventing noise.
- They work on three main techniques — absorption, diffusion and reflection.
- For indoor sound treatment in spaces like recording studios, the three most commonly used devices are absorption panels, bass traps and reflection filters.
This is a domain where the knowledge never ends. You can expand the scope of your learning by going through more noise-reducing devices and materials like heavy curtains, foams, blankets, and understanding how they work. I hope that with this tutorial we have brought you a step closer to your ideal soundproofing project.