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What Is Soundproofing? — How Acoustic Insulation Works

Silent Home Hub What Is Soundproofing

Soundproofing is the method of noise reduction or blocking noise from:

  • Entering a room or;
  • From leaving a room

So if you want a room where you can…

  • Have private conversations without others eavesdropping
  • Play guitar or any musical instrument without disturbing your neighbors or family members
  • Play video games and SHOUT a lot without being heard
  • Want a peaceful area to meditate, focus, and work without any interruptions

Then…

This article is for you!

We’ll break down all the details about soundproofing, how it works, types of noise, and our best tips and materials to use!

Table of Contents

What Is Soundproofing and How Does It Work?

You already understand the basics of what soundproofing can do for your home and your life.

To understand how it works, there are 2 types of sound you should understand first.

Soundproofing works by tackling these 2 types of sound: airborne and impact/structure-borne noise.

Types of Noises

Airborne Noise

Airborne noise is the most common sound within a room. The technical definition of airborne sound is sound waves traveling through the air.

These sound waves are caused by:

  • Someone talking
  • Music being played
  • A radio playing music
  • Your TV
  • Traffic noise

Essentially, airborne sound is noise that LEAKS through any openings or gaps in your room or house. In other words…

  • If your doors have openings or gaps, sound can leak in
  • If your windows have openings or gaps, sound can leak in
  • Your air vents have “air holes” where sound can leak in
  • If your ceiling has a damaged opening, sound can leak in
  • If your drywall has small holes (even in the edges), sound can leak in

All the sound waves that come in and out of your room can turn out to be irritating and noisy waaay beyond your tolerance levels.

This is where soundproofing becomes an effective way to block or reduce the noise pollution infecting the area.

BUT! There’s ONE MORE type of noise you need to understand: Impact noise.

Impact Noise

If airborne noise is sound that travels through the air, impact noise is sound that travels through…

Solid structures — like your drywall, floorboard, ceiling, etc.

Think of impact noise this way: If you live in an apartment or condominium, the walls or drywall aren’t thick enough to block noise.

Your wall — which is the first defense against your neighbors’ voices or perhaps their rock concert session in the next room — SHOULD BE thick enough to block noise from entering your area.

If it’s too thin, sound can easily leak through due to the vibrations or the IMPACT that sound makes. Here are common examples of impact noise:

  • Footsteps walking heavily on a floor
  • Hammering a nail
  • Closing a door
  • Banging on a wall
  • Dropping a heavy object on the floor

When you hear the word impact noise, remember this: Impact noise happens when someone creates an impact against a solid structure (hammering a nail to a wall). This creates vibrations which are carried through the wall and then eventually…to your ears.

3 Ways to Reduce and Block Sound From Entering Your Room

Now that you understand the 2 types of sound you have to block and reduce in your space, let’s go over the 3 methods to reduce sound.

#1 Increase Airborne Noise Isolation

Airborne noise isolation is a fancy way of saying that you want to improve your room’s effectiveness in blocking sound.

How do we do it?

First, identify the areas in your space where air can enter. This can be your floorboard, your windows, doors, and air vents.

Second, use soundproofing products to reduce or block sound energy from entering, such as:

  • Door seal kits
  • Weatherstripping
  • Acoustic window inserts
  • Acoustic sealants (Green Glue)

Don’t worry; we’ll discuss more about these soundproofing products later. For now, take note of these methods to reduce sound in your air space and improve speech intelligibility.

#2 Increase Structural Mass

If the majority of your noise problem is impact sound, you’re already aware the sound source comes from impacts made mostly to your walls, floor, or ceiling.

Loud footsteps, banging, and occasional dropping of objects are sounds you want to eliminate.

One way to solve this problem is by INCREASING the mass of your structures. This means using thicker drywall or adding an extra layer of drywall to give it that double-layer effect and thickness.

How Does This Help?

The concept behind increasing structural mass is allowing your walls to have a DENSER structure. As a result, your walls are MORE EFFECTIVE in reducing vibrations created by any impact.

#3 Improve Impact Sound Isolation

Improving impact sound isolation is a similar sound reduction method to increasing your structural mass.

Let’s say you’ve successfully increased structural mass in your room by adding more stud walls or an extra layer. But for some reason, it’s still not enough in reducing sound.

What you can do is install damping products between your stud wall and framing for even better sound proofing.

Some examples of damping products include:

  • Rubber isolator
  • Acoustic panel
  • Decoupling (more on this later)

With all these methods and the best material to soundproof sounds, how do you know which ones are ideal for your space? How do you know which is the MOST effective in reducing sounds?

The next section will discuss this further.

How Effective Is Your Soundproofing?

For the next 2 sections below, we’ll dive into a more technical sound quality aspect: STC and NRC ratings.

Pro Tip: We recommend consulting a sound engineer to get ACCURATE readings for both STC and NRC. 

Sound Transmission Class (STC) Rating

Sound Transmission Class is a measurement used to determine how effectively a certain product can stop sound from entering a wall.

Let’s say you decide to add MLV (mass-loaded vinyl) to your partition wall. The STC rating tells you how much sound MLV can block or stop.

Rule of thumb: The higher your STC rating, the better it is at noise reduction.

Calculating STC can be somewhat a complicated process, especially for first-timers. That’s why we recommend a sound engineer to help you rather than DIY everything on your own.

However, it helps to know the factors that contribute to your STC rating, such as:

  • Decibel (dB) – Decibel is a unit of measurement that tells you how loud the noise is. Below, you’ll see a table that shows different types of noise and their corresponding decibel ratings. Traffic noise, for example, averages between 80 to 89 dB depending on how heavy the traffic is. Any sound ABOVE 85 dB is harmful.
  • Transmission loss – Transmission loss is a unit of measurement that tells you the volume difference (dB) between two walls or structures. Let’s say your wall’s dB rating is 90, and the rating on the other side of your wall is 60 dB. You have a 30 dB transmission loss. The way we interpret this is: 30 dB less sound energy made it through the wall.
  • Frequency (Hz) – Frequency, which is measured in Hertz (Hz), measures the tone or musical note of sound. Think of high pitch and low pitch sounds. For example, a flute can reach a frequency of 2000 Hz, while a piano can have a low pitch at 27.5 Hz or a high pitch as high as 4186 Hz!

We mentioned earlier that the higher your STC rating, the more effective it is in reducing sound.

Here is a chart that provides more detail on STC ratings:

Noise Reduction Coefficient (NRC) Rating

While STC tells us how much sound a certain material or product blocks, NRC tells us how much a certain material or product ABSORBS.

Unlike STC, which comes in a wide range of values, NRC ratings range from 0 to 1, where:

  • A 0 NRC rating means the product absorbs no sound.
  • A 1 NRC rating means the product absorbs all sound.

Calculating the NRC rating of products requires much more work. You’ll need a special sound test lab room designed specifically to measure sound absorption.

You’ll also need sophisticated or high-quality equipment and microphone to accurately perform the tests.

Again, we highly suggest consulting a sound engineer to get accurate NRC and STC ratings.

Soundproofing vs Sound Absorption vs Sound Decoupling

You’re probably wondering why you need to know what sound absorption and sound decoupling are.

The truth is, soundproofing only solves ONE part of the problem. You can have other noise problems or frequencies you want to eliminate.

Now, we didn’t create this guide to give you half-baked solutions. That’s why this section is a MUST-READ.

This is where sound absorption and sound decoupling come into play.

In fact, all three are connected to each other if you want the best acoustic environment.

Let’s start off with…

Soundproofing A.K.A Sound Insulation & Acoustic Insulation

You’re already aware sound can easily pass through the air and travel through walls. This outlines the majority of problems most people face when they complain about hearing too much noise pollution.

Soundproofing is also known as SOUND BLOCKING. This means sound escapes rooms much lesser.

Since sound doesn’t escape or leak as easily out of your rooms, soundproofing products or sound blocking means you don’t have to worry about disturbing your neighbors’ peace.

BUT WHAT ABOUT YOUR PEACE?

While soundproofing products lead to noise reduction in your room, the biggest problem now is you’ll be hearing all the sound instead!

Allow us to explain in the next section.

Sound Absorption A.K.A Sound Dampening

Think of it this way:

  • You’ve successfully warded off angry neighbors from knocking on your door and listen to their rants and complaints.
  • If you’re a musician who plays loud instruments all the time, soundproofing your space now means you can play as loud as you want without disturbing the community’s peace.
  • But because sound DOES NOT escape your air space anymore, that also means it practically STAYS within your room!

What you end up feeling is an increased reverberation or echo and generally higher sound intensity in your room.

Since all those sound waves are circulating your room, it’s now time to turn to sound absorption!

Sound absorption is the method of using sound-absorbing materials or sound absorbers to absorb sound in a room.

Sound-absorbing materials include:

  • Acoustic panels
  • Insulation foam
  • Cork
  • Acoustic foam

With sound-absorbing and blocking materials installed, you…

In fact, using sound absorbers or acoustic panels IMPROVE the sound quality within a room.

BUT WAIT! There’s one more you need to know!

Sound Decoupling A.K.A Sound Diffusion

Sound decoupling SEALS the deal.

And when we say SEAL, we mean for good. What’s the purpose of sound decoupling? Its main purpose is to reduce vibrations between objects.

In layman’s terms, sound decoupling is a form of noise reduction where,

  • Separate an object or structure into 2 separate objects
  • The separation causes each structure to vibrate independently instead of vibrating all at once
  • Ultimately, this prevents sound from passing through the other side

What sound decoupling does is it BREAKS the path of those vibrations from passing through. Before the sound reaches you or enters your room, decoupling “cuts” the sound!

Decoupling is also a common form used mostly for ceilings and walls in rooms. Although, it’s not as common for floors.

Which Method Should I Use?

Which noise reduction method is best? Soundproofing, sound absorption, or sound decoupling?

It’s not a matter of which method is the best, but rather a combination of sound-blocking and sound-absorbing materials, along with decoupling that fully reduces and blocks sound.

Whether you want to prevent sound waves from “invading” your air or infecting your structures, a combination of all these noise reduction methods makes for the perfect sound barrier to give you ultimate peace.

How Loud is TOO Loud?

So you’ve successfully identified the source and determined all the ways to completely soundproof your space.

You’ve even consulted a sound engineer to ensure TOTAL effectiveness. But it’s impossible to say your entire house would be completely soundproof.

In fact, some amount of noise is necessary. But the keyword we’re aiming for here is “tolerate.” Or rather, how much noise pollution can you tolerate?

Why is this important? Because TOO LOUD can harm your health. To understand more of what this means, let’s define what decibels are.

What Are Decibels (dB)?

Decibels are a unit of measurement used to indicate HOW LOUD something is. For example, breathing emits noise, but only at 10 dB! That means it’s pretty faint to hear.

Generally, decibel ratings between 0 and 60 are considered safe to your ears. Decibel ratings between 70 to 85 typically make anyone feel annoyed or irritated. But what about decibel ratings after that?

  • 80 to 85 dB – Hearing damage after 2 hours of constant exposure
  • 95 dB – Hearing damage after 5 minutes of constant exposure
  • 100 dB – Possible hearing loss after 15 minutes
  • 105 to 110 dB – Possible hearing loss in less than 5 minutes

The higher the decibel ratings, the more dangerous it is to your health or to your ears. Sounds in the 80 to 85-decibel range include gas-powered lawnmowers and leaf blowers or heavy traffic.

Steer clear from decibel ratings at this level. And if you’re constantly exposed to this range of noise pollution, be sure to soundproof your space!

Now that you know HOW LOUD is TOO LOUD, let’s dive into the costs of soundproofing.

How Much Does Soundproofing Cost?

The average cost of room soundproofing is $1,600. However, if you want to go the distance and spend extra, this can cost you between a range of $2,500 to $4,000!

Here are factors that contribute to the total cost:

  • Labor
  • Materials used
  • Tools needed
  • The size of your place
  • Type of materials (e.g., acoustic tiles, MLV, solid-core door, etc.)
  • How complex or simple the project is (it’s more costly to soundproof a basement than it is to soundproof a smaller bedroom)

What if you only want to soundproof specific parts of your house? Here’s a breakdown:

  • Windows – This can fall between $300 to $1,500…PER WINDOW. Soundproof curtains are a great solution, but curtains might not be enough at times, so inserting window inserts or acoustic sealants can rack up the cost.
  • Doors – Adding sound absorbers to your door can cost around $300 to $455. But if you want a sliding glass door or a solid core door, this can increase the price between $1,300 to $4,000!
  • Ceiling – You can use acoustic tiles or acoustic foam for your ceilings, which should cost between $230 to $280.
  • Flooring – Because flooring covers a wide square inch of area, costs can be as high as $1,000.
  • Walls – This mostly depends on the material you plan to use and how big the space is. For example, an acoustic tile costs $10 per 20-inch square, while textured panels are priced between $1.60 to $4.60 per square foot.

Best Tips and Materials for Soundproofing

Believe it or not, soundproofing isn’t limited to rooms or a house. If you want to go the extra distance and say, soundproof your car, for instance, there is a way to do so!

And that’s what this section is all about. Our tips and best soundproofing materials to use for your noise reduction projects!

How to Soundproof Your Car

Who would’ve ever thought you’d need to learn how to soundproof cars, right?

Now you know it’s entirely possible! Here are a few basic tips to help you get started:

  • Install foam insulation in your car’s doors
  • Use sound-deadening mats for your car’s floor
  • Sound-dampening mats insulate the noise in your car’s roof. The best part? It’s as simple as peel and stick!
  • You can also use sound-deadening mats for your hood!

The best brands to use would be Noico and Dynamat. There’s even sound deadening spray to enhance the effect!

These work great at reducing sound from the road and improve the sound quality of your car speakers!

Dealing With Computer Noises

Some of us enjoy the tacky and clicky sounds of our fingers typing on the keyboard.

But not everyone can deal with all the random computer noises. And it’s even more irritating than a car honk at times. Not to mention, other PC components could add up to the overall noise.

So here’s what you can do:

  • Ensure the screws behind your PC are secure and tightened appropriately.
  • Buy sound dampening mats and install them in your PC where airborne sound can easily leak through. But be sure not to cover areas that stop the airflow or proper ventilation of your PC!
  • Invest in SSD (solid state drive). PCs can come with either an SSD, HDD, or both. If your PC has an HDD, we suggest upgrading it to an SSD since these don’t have spinning disks. HDDs have spinning disks that can, at times, emit sound.

Home Soundproofing: Rooms, Walls, Ceilings, Windows, Doors, & Floors

Home soundproofing is a large-scale project that can take months to finish!

The proper methods for soundproofing a room require various materials, depending on HOW SOUNDPROOF-ED you want your house to be.

But don’t worry! Here are a few of the basics to guide you. 

For Walls

The 1st thing you want to do is check for any weak spots or gaps in your wall. If you notice any gaps or cracks, using Green Glue noise-proofing compound is one of the cheapest ways to achieve sound reduction.

Other price-friendly options include moving blankets, blackout curtains, and other wall hangings like tapestries and paintings.

But if you’re willing to shell out more, adding an extra layer of drywall and soundproof foam panel does an excellent job!

For Ceilings

Decoupling, mass-loaded vinyl, and acoustic tiles are your best options! But if you want something cheaper for soundproofing a room ceiling, you can use a dense rug.

Although, a rug won’t exactly look aesthetic.

For Doors

Weatherstripping and green glue sealant are your most trusty sidekicks when it comes to a soundproofing a room door.

Take it a notch further by installing a door sweep to prevent that banging sound! But if you have the cash and are willing to spend for it, turn your hollow-core door into a solid core door!

For Floors

Acoustic underlayment and carpets are two of your best options. Acoustic underlayment will cost much more than a carpet, but the effects are twice as effective too.

Quiet Pets and Pet Items to Buy

So you want a quiet pet for your apartment? We’ve got some unique ideas and pets you can buy without disturbing your neighbors!

  • Ferrets
  • Cats
  • Gerbils
  • Guinea pigs
  • Turtle
  • Rabbits

Okay, so they might not be as playful as dogs, but if you’re looking for a pet that keeps you company that doesn’t disturb the peace and stays by your side on lonely, rainy days, these pets will cuddle with you!

Office Soundproofing Guide

The extent to how much you can soundproof in your office depends if your employer allows it.

Some crafty ideas include:

  • Installing foam in any gaps, air holes, or cracks you see in your office space
  • Sound-absorbing noise panels are your best option, but again, due to their size, you’ll have to ask your employer if you’re allowed to do this
  • Try a white noise machine! This can be especially helpful if you share office space with several colleagues
  • Finally, try to suggest investing in quieter machines like a quiet paper shredder, quiet desk fans, and so on.

Want more ideas? We’ve got TONS MORE in this Guide on Office Soundproofing!

DIY Soundproofing Materials to Consider

If you’re looking for cheap and effective soundproofing products and sound absorbers to soundproof your space, these should do the trick:

  • Acoustic sealant – Simply layer the glue on the cracks and gaps of your windows, doors, etc.
  • Room dividers – Room dividers are bigger than regular curtains and do a fair job of blocking sound in-between spaces
  • Dense rugs and blankets – Heavy rugs can be an alternative to a door sweep, while blankets are a fairly decent material for your door or even window!
  • Add or rearrange furniture – Soft fabric objects are better than hard fabric types. This won’t reduce sound as much, but i’s an actionable tip you can try right this very minute!

But that’s not the end of it. There are still TONS of other options we’ve outlined for you in our Complete List of DIY Soundproofing Materials.

Important Note About DIY Materials

DIY materials ARE NOT permanent solutions.

These are temporary fixes that can help reduce sound, but not by a lot. Ultimately, we recommend investing in actual soundproof products designed specifically to soundproof your house.

Since DIY materials are not ideally designed for blocking or absorbing sound, these will obviously result in a weaker soundproof environment.

Conclusion

couple sitting down on couch

Case and point, soundproofing is the method of reducing or blocking noise by:

  • Increasing structural density
  • Improving airborne sound insulation
  • Improving structure-borne insulation

Additionally, it’s a combination of decoupling, sound-blocking, and absorbing products to fully soundproof your place.

Remember: sound at high decibel levels can harm your health, so even basic soundproof methods are beneficial to your life!

About the Author

andrea_adams

Andrea has always been bombarded by the hustle and bustle outside her home. Living in the city doesn’t get any quieter. The never ending noise from construction, traffic, and dogs barking on the streets day in and day out drove Andrea to a breaking point.

For 3 years, Andrea committed herself to studying DIY hacks, performing soundproofing experiments, and installing noise-free solutions. Now, she lives a quiet life free of the stress from noisy environments.

She hopes to share this knowledge so that others don’t have to endure the noise reigning in their ears and live a peaceful, stress-free life.