How Does Soundproofing Work: 4 Best Ways

Are you considering soundproofing your house? Would you like to learn more about it and understand how does soundproofing works and the science behind sound insulation?

Let’s face it: sometimes, too much noise surrounds us. Noisy neighbours upstairs, loud music next door, or even sounds from the outside might disturb your peace. 

And you’re right in trying to do something about it. 

Soundproofing, or sound insulation, is one of the most effective ways to block sound waves from entering your home. 

But before you start researching different soundproofing materials and methods, it’s good to understand how soundproofing generally works. This page is about that. 

Below, you’ll find information on how sound works and the different soundproofing methods that prevent sound from travelling through walls, floors, and ceilings.

We have a lot to cover, so let’s get right to it, shall we?

What is Soundproofing?

A quick note: To learn the basics of soundproofing, check out my full explanation of what it is and is not.

Soundproofing is the process of blocking or reducing unwanted sounds or background noises from entering your house or being heard outside of it. 

This means using various materials and techniques to increase sound isolation and mass to reduce sound vibration. 

I must be upfront: Many sounds cannot be fully eliminated. It’s impossible, at least not without structural severe and construction work, to soundproof a room so no sound can enter from outside. 

However, you can significantly reduce noises and sounds to become bearable or no longer notice them. 

And that’s the goal of soundproofing. Here’s how you achieve it. 

How Does Soundproofing Work – The Science Behind Sound Insulation

To understand how soundproofing works, we have to start by discussing the science of sound. 

Only when you understand how sound works and how sound waves travel can you comprehend the different strategies for stopping or absorbing it. 

So, what is sound? Well, in the simplest terms, sound is energy. Sounds are produced when things vibrate. That vibration is then pushed outward, away from its source. The sound energy travels by making the air or objects around it vibrate, too (which is important to remember, as you’ll see shortly).

The process continues until this energy (or vibration) reaches our ears. 

Another important thing to understand is how sound travels.

Remember, just a couple of lines above, I mentioned that sound energy makes air and objects vibrate. But it doesn’t happen at the same time. This means some sounds travel by making the air vibrate, and some because objects vibrate. We refer to those sounds as either airborne or impact. 

Airborne sounds are created when the sound energy travels through the air. This is what happens when you speak, for instance. Your voice makes the air vibrate, and that’s how your words reach the other person. TV, radio, and speaker music are other examples of airborne sounds. 

These sounds typically enter your house through vents, open spaces, cracks, doors, and electrical outlets. In short, if air can get in somehow, an airborne sound will also get that way.

Take a look at this room. 

You can immediately see several places through which airborne sounds can be heard:

• Gaps in old window frames
• Window lock
• Gaps under windowsills
• Chimney
• Crack in the wall above the mirror
• Electrical outlets
• Ceiling lamp, and more.

On the other hand, impact sounds happen because the sound makes objects vibrate. So, you hear footsteps because the floor vibrates as you walk. You hear someone hammering a nail into a wall next door because the sound of their hammer hitting the nail makes the wall vibrate, and so on.

Impact noises are the most common sounds that travel through walls, ceilings, and floors. 

Because these two types of sounds work differently, they also enter your house in different ways. 

Soundproofing works by reducing or absorbing the sound as it enters your house. 

For airborne noise, for example, you soundproof the house by closing cracks, wall gaps, window drafts, etc. Air can get into the room through these cracks, and since these sounds are carried by air, they can enter the house that way, too. 

For impact noises, you use methods like sound dampening to reduce the impact of the vibration. To do this, you place various dampening materials between various structural elements of the building – between sheetrock and framing, for example – to stop impact sound energy from being transmitted.

Different Methods of Soundproofing

Because we’re dealing with different sounds, we use different methods to block, reduce, or absorb them.

• How to Block Out Noise Without Earplugs: 7 Solutions for Better Sleep

There are four methods to soundproof a house.

#1. Blocking all entry points for airborne sound to prevent noise from leaking in or out

The most basic way to reduce the impact of airborne noise is by sealing and soundproofing all of its entry points. In practical terms, this means sealing all openings in walls, ceilings, floors, doors, windows, etc. 

Various products, such as acoustic sealants, door seals, acoustical window inserts, and more, help close sound leaks. 

#2. Damping parts of the structure so that less sound energy travels through it

Sound travels through solid materials—walls, floors, and ceilings—and is a major cause of noise pollution in houses, apartments, or offices. 

Moreover, it often comes out on the other end with a similar intensity and volume. 

You eliminate that problem by placing sound-damping materials along the path of soundwaves travelling through the structure. 

Let’s use a wall between two rooms as an example. The chances are that the wall has a multilayered structure. There’s sheetrock on one end, the wall frame in the middle, and another layer of sheetrock in the next room. 

Sound can make each layer vibrate with the same intensity, meaning that the sound can enter the next room at a similar level as at its source. 

Damping materials reduce the intensity of sound. Of course, sound may still enter the room. However, those materials greatly reduce the sound’s volume, often to a point where you either don’t notice it anymore or are not disturbed by it. 

Some of the techniques used to damp these noises include:

• Sound-absorbing materials like RSIC clips, rubber stud isolators, floor underlayment, or elastomeric sheetrock glue (also known as green glue) can be installed to help dampen noise transmission.
• Adding acoustic foam, panels, soundproof foam, or mass-loaded vinyl adds noise-reducing mass to the structure.

This image shows some places where you could add damping materials and reduce the impact of sound transmitted through walls. 

#3. Increasing structural mass

Finally, you can reduce vibration by creating a denser structure in your walls, ceilings, and other structures.

In this case, you aim to place an obstacle to reduce the energy transmitted with the vibration. 

Unfortunately, this method is only suitable for new builds and requires changing or adjusting the wall, ceiling, or floor structure. 

For example, one of the most effective ways to increase structural mass is by adding double-layered sheetrock to walls. You can also increase the thickness of wall framing and use heavier and denser building materials overall. 

#4. De-coupling one structure from another

Finally, you can also decouple or separate one side of the structure from another. As a result, each side vibrates independently, making transmission of structure-borne sound impossible.

Again, this is quite a complex method, often involving constructing a room within a room. 

Some ways include using double-stud or staggered stud walls and implementing resilient sound insulation clips and hat channels.

And that’s it…

Now that you know how soundproofing works, you should learn how well it works and what sounds it can reduce or eliminate.

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