Soundproofing and Sound Absorption: What’s the Difference?

Recently, especially since I have started this blog, more and more people come to me asking for an advice.  In this manner, I get a lot of questions about soundproofing and sound absorption, what is best to apply, how it can be done, but mostly regarding the difference between the two of them.

I understand that it can be confusing but there is a major difference between soundproofing and sound absorption.

Usually, when people have a problem with unwanted noise, they want the sound that is being made inside the room to keep it in the room or they want to prevent the sound from entering the room. This is commonly known as soundproofing.

On the other hand, people may want to reduce the echoing or reverberation of the sound within the room. Namely, they are looking for an installation of sound absorption.

soundproofing vs sound absorption

Depending on what you want to do and what problem you are dealing with, there is a different solution which you can apply.

Importantly, you should keep in mind that both types of products enable reduction of an unwanted sound but by very different means.

If you want to improve the room’s acoustics, you should consider using products that can absorb the sound within the room. Whereas if you need to keep the sound out of your space or you want it to stay in the room, there are products which you can use that are able to block or stop the sound from coming in or out.

Now you may be wondering how you can distinguish these two types of acoustics and what those products should be made of for each of them. The rest of the text is going to give you an answer to each of your questions with regards to a detailed explanation of both soundproofing and sound absorption.

Soundproofing and Sound Absorption: The Difference

Soundproofing

As for soundproofing, it is used to block an unwanted sound from either entering or leaving a space. In this way, the sound made inside the room stays in the room, while the noise from the outside is drastically reduced within the room.

For instance, the sound made inside the room is being reflected back to the room by the soundproofing product, so it cannot be heard in the next room, i.e. the sound is blocked from leaving the room.

On the other hand, the sound can be reflected back to the outside by the sound absorption product, so the sound cannot be heard within the room, i.e. it is blocked from entering the room.

Think of it this way; if you want to stop a sound that travels from its source through various media, and reaches your ears and brains, you need to interrupt the chain of events.

Soundproofing serves for this purpose, stopping the sound. But you have to choose a soundproofing product according to its material and also pay attention to noise frequencies and a location that needs soundproofing.

Concerning the products designed to block a sound, they are, usually, made of dense, heavy, cumbersome materials. Also, they should separate two sides of a wall, or even a window.

And most importantly, those products are always found inside the wall construction.

reduce bass noise from neighbors

Being made of this type of material helps them reflect the sound back. Therefore, the stress is on reflecting the sound - not absorbing it, as it is the case with sound absorption.

Importantly, there are three things that you need to consider in order to achieve successful soundproofing. One method may be enough but if you need stronger soundproofing, think about combining them.

  • Mass – All heavy and thick materials will block a sound.
  • Dampening – It is best achieved with dampening compounds applied between two stiff panels.
  • Decoupling – With gaps made in certain parts of a structure’s sound, vibrations are easily interrupted.

Click here to see some of the best sound deadening materials.

Sound Absorption 

When it comes to sound absorption, things are pretty opposite. Instead of blocking it, a sound is being absorbed by a sound absorption product reducing the unwanted noise, such as echo, within a space.

To make it simple, it may be said that sound absorption is a process by which a sound is soaked up by specially made sound absorption material.

Let’s illustrate sound absorption. Imagine that sound absorption product can fill with a sound, absorb it from the room, and let it go through to the other side of the wall. That’s the whole thing with it.

With the installation of sound absorption, the sound you make within one room can be heard in the next room, since the material only absorbs the echo of the sound.

acoustic panels soundproof foam

With regards to sound absorption materials (also called sound absorbers or sound diffusors), there are products specially designed to absorb an echo within a room. Generally, they are made of soft, light, fluffy, or porous materials.

As they are designed in this way, they soften up the surfaces in the room and reduce the echo within it.

Being made of this type of material helps them absorb a portion of the sonic energy of the sound waves. As a result, the reverberation is reduced creating the decreased noise and echo. In the end what we get is a clear and audible sound within the room.

I had a chance to hear from a lot of people that it is “generally known” that foam serves for soundproofing, being one of the best materials which block a sound. You also think that, right?  In fact, the truth is the opposite.

do foam bass traps work

Actually, foam does not block a sound but rather it absorbs it. Therefore, it presents one of the best materials not for blocking a sound but rather for absorbing it. 

(Read more here: ​Do Foam Bass Traps Work?)

As you may wonder what exactly those absorption materials are, here is the list of three most common types of them.

  • Porous absorbers – They consist, obviously, of porous materials. Their main function is to convert the energy of a sound into heat energy. They are one of the most popular types people use since they are pretty successful when dealing with mid-range frequencies of a sound.
  • Panel absorbers – They are also called membrane or single absorbers since they are everyday objects, a table, chair, or window, being made of non-porous and non-rigid materials. If you have a problem with the rather low frequency of a sound, this type would do a great job of absorbing the sound.
  • Resonance absorbers – They consist of a mechanical or acoustical oscillation system where they have plates which are made of perforated material or ones made with holes or some openings. In fact, these holes and openings can trap a sound and lock it inside them. 

Click here for a more in-depth look of the best sound absorbing materials.

The Products You Can Use

I hope that by reading this text you have got a pretty clear understanding of what is the difference between soundproofing and sound absorption.

But how can you use this in practice? What are the actual products you need to buy in order to soundproof your house or make it absorb a sound? Here are the most common ones.

Soundproofing Products

  • Mass-Loaded Vinyl barrier (MLV) - This material consists of two main ingredients: vinyl and high mass element. It possesses high density and it can be used in soundproofing walls, ceilings, floors, pipes, office partition walls, and many other places.
  • Resilient Sound Isolation Clips RSIC-1 - They are used especially to retrofit and improve walls and ceilings. You should consider this material if decoupling is the method you want to apply.
  • Soundproofing Window Kit - It is easily installed and removed and it provides definite protection from a noise. You need to consider this option if you are dealing with a high frequency of a noise, such as a train noise.

Sound Absorbing Products

  • Acoustic Foam - It presents the most widely known material due to its effectiveness and the fact that it is not pricey and difficult install. Also, it can be beautifully designed and contribute to the aesthetics of your home. However, the best places to install it are small and mid-sized places.
  • Acoustic Fabric Panels  - This material is successful in controlling reverberation and echo. The fabric is attractive and it may include a high-density fiberglass to maximize sound absorption.
  • Sound Absorbing Underlayment - It provides the best solution for hardwood and laminate flooring. It is installed under the floor, so it is out of your sight while the noise from underneath is muffled. Being made of felt, the sound within the room is softer since the echo is reduced.

Final Word: On Soundproofing and Sound Absorption

Has it been very difficult to comprehend these complex matters? The important thing to remember is to employ specific products when you want to improve your room’s acoustics while you need to install completely different ones to block a sound from coming in or out of your room.

Finally, if you are looking for an overall sound isolation, you should consider installing both soundproofing and sound absorption products to achieve the best isolation possible.