How To Soundproof An Already-Built Wall

Soundproofing is an interesting phenomenon of acoustics to reduce a significant amount of noise inside rooms. To reduce the noise, you need to increase isolation. To increase isolation, more structural mass is required. Creating a denser structure makes it more difficult for sound vibrations to move through it.

How are walls usually built

Most rooms have flat walls and ceilings and sound bounces off these surfaces. So how does that affect the sound? Here is a brief demonstration. Take two ping-pong balls and throw them straightforward together at the same time. Tell your friend to stand in the way. The first ball must hit the sidewall and let the second one go straight forward. Try to pass the later one nearby your friend’s ear. We notice that the reflected sound arrives at our ears later than the direct sound, even though it starts out at the same time because it is traveling farther. Now in an average room, there are 6 such flat surfaces (4 walls, 1 floor, and a ceiling), and together these surfaces create a lot of reflected sound.

According to the history of soundproofing, a design for noise barrier construction was proposed in California back in 1970. The materials used in the design were absorbents such as porous and resonant absorbents. The porous absorbent ensures the frequency distribution of sound at the cellular level; whereas, the resonant absorbent dampens the noise wave after reflection.

Is it worth soundproofing an already-built wall?

Absolutely yes!, depending on the conditions. You need to analyze the level of noise reaching into your rooms. Put in check the noise level to be reduced and look for the appropriate materials that can dampen the external sound. If you are staying in a busy residential place and find difficulty recording for your sessions, then soundproofing might help a considerable amount. Obviously, you cannot expect your room to be 100% noise-free. Hopefully, a scientist may come up with a new invention later in our lives which might revolutionize sound technology with 100% noise blocking. Till then, stay happy with acoustic foams or moving blankets.

Can you feel the difference after soundproofing?

Oh Yes! Ever since I have noticed that my room was echoing a lot, I decided to try acoustic foam wall panels. It was a very easy process, as there is a cardboard backing on the back of the panels. These panels have double-sided tape, all you need to do is peel off the tape and stick them on the walls without destroying them. Since then, I have noticed a big difference in the sound quality. It helped a lot to improve the sound quality in my room, especially while recording. However, I don’t need to put those panels near or on the closet panels. Clothes already act as a good noise absorbent.

But if you are like, huh, why should I pay for those black and ugly foams just to make my room sound a little less noisy?! You may use moving blankets. Along with that, it is not necessary to cover your entire room with noise absorbers. Rather, it is much important to select the direction of the source of the noise.

Types of walls suited for soundproofing

All types of walls are suited for soundproofing, whether it’s for at home, office, schools, basements, movie theater rooms, police custody rooms, machinery enclosures, or to resolve attenuation problems in schools or religious worship places. For the noise-free and comfortable journey, soundproofing service is well employed in trains and boats. It also is efficient for reducing impact and airborne noise in airplanes. They are not space invasive but highly effective in reducing noise levels.

In the case of corporate offices, they have installed exterior soundproof glass walls. This transparent acoustic solution also is implemented at private businesses and shopping complexes. These laminated glasses are very efficient noise repellents. There is nothing like absorption here, rather noise fades away mainly. Along with that, these glass walls are also helpful for conference halls in order to avoid distractions to other employees and maintain a professional environment.

You may have heard sound from the ceiling. Sometimes, the ceiling upstairs may have a hollow cavity, and, when the people are walking, the tapping sound can be heard clearly. Its echoes reverberate which is very annoying. So if you already moved into a new house and find yourself disturbed by the kids upstairs, consider buying a compression fit product, which you can use to fill up the ceiling cavity.

What options do I get to soundproof a wall already built?

Ideally, you want a blanket with the cover where the fabric is not tightly woven. In the case of synthetics, the fabric is tightly woven which is going to reflect some sound, so it’s not going to be as effective as a blanket that had a coarser weave. Typically, a natural fiber absorbs sound better and is less likely to reflect the sound. Even though such blankets are quite heavy, they have a porous fabric on the outside and it does a great job in reducing the echo.

I use the combination of different absorption foam panels. Such panels are not a standard cardboard or egg crate or mattress thing. Those all are crap. Most of the wedge foam panels come with a pattern of 12 by 12 inches or 24 by 24-inch panels. The thick triangular shaped structures made on the panels are 2 inches thick. You can even get those panels with triangular patterns extended up to 4 inches thick, considering you have extra bucks to spend.

However, I find this soundproof material cool enough to add a good background effect.
Even though I have abounded my room using all sorts of soundproof materials, the ceiling should not be ignored. There are two types of noises we experience through the ceiling, airborne noise and impact noise.

Therefore, to reduce the effect of such noises, ceiling insulation must be done for effective results.

What materials do I need?

You can use sound blankets to cut down on some echoes. You can pretty much cover some hard, flat surfaces. I prefer to use some larger blankets. These blankets are specifically designed to absorb the sound, and they have a significant noise reduction coefficient. I can use a C-stand (century stand) and steel conduit pipes easily available at hardware stores. Now what I can do is suspend this between two-century stands. Then I can hang the blankets using spring clips to keep the blankets secured to the conduit.

For the walls, floors, and ceiling, acoustic foam wall panels are considered one of the best materials to block the sound waves. Drywall is another soundproof material which comes in two categories. The first one is regular drywall that includes layered gypsum and plasterboard.

Both of the materials are quite cheap and light. The second one is the damped drywall which consists of a damping layer. This damping layer is nothing but filled with compounds between two regular drywall. For ceiling insulation, a timber joist soundproofing system is much preferred nowadays reducing both airborne and impact noises. For the floor insulation, a specialized foam made of cork or rubber is used which we can apply easily underneath carpets, timber floors, or vinyl floors.

Don’t ignore the doors. Even if you have furnished your walls and ceilings well enough, you may still get some echoes from the doors. I suggest you consider doors made of solid cores, not as a regular hollow door. To ensure the better enclosure at the entry door, weather-stripping is layered around to avoid air leaks. The materials used to make weather-stripping is generally made of self-adhesive foam or rubber which also aids the interior temperature during winters.

One of the most vital applications of soundproofing is to provide noise-resistant interiors in airplanes. We generally don’t get an idea of this application initially while talking about soundproofing but imagine how pilots and crew members are adapt to such an environment. Thus, material like fiberglass composite comes to the rescue. It not only blocks high-frequency sound waves but also is a high level of heat.

One more material which has an important role in noise reduction is wool felt. With the combination of synthetic fiber and wool, the material becomes denser and capable of absorbing cabin noise. Therefore, we can communicate easily with each other and sleep comfortably. Otherwise, we can’t imagine the terrible noise within airplane cabins without soundproofing materials. The noise from propellers or turbulence is terribly intense, even a pair of high-quality earplugs would not work.

The use of glass materials in an office building is a great way not only to reduce the external noises but also cost-effective and lightweight. The curtain wall is a kind of soundproof wall employed in corporate buildings. Two layers of insulating glass materials are laminated with a thickness of about ¼ to 1 inch. The lamination, which is made of annealed glass, aids in higher sound insulation. Such layered glass walls effectively reduce the external noises like traffic or constructions keeping the interior peaceful enough.

How to soundproof an already-built wall – step by step?

It’s tutorial time

Let me say something about sound waves. When we make a sound, suppose a clap, inside a closed regular room, the original sound waves are distorted by strong later arriving reflected waves. The speed of sound at a room environment is about 331 m/s and sound waves will bounce back and forth multiple times filling the room. This creates a lot of sound reflections and echoes which often turns out to be disturbing.

So in order to make your stay at home a peaceful one, I have come up with an easy and step by step tutorial on how to make your room soundproof.

1. 1. 1. Use damped drywall that looks like two layers of regular drywall boards. Two drywall are sandwiched together using a proprietary glue which restricts the sound transmissions. Using this damped drywall is equivalent to putting up multiple sheets of regular drywall which creates more fluff in your room than required. Pay particular attention to electrical outlets. Spray foam is applied on the drywall, and you need to cover those openings beforehand.
      2. There’s no need to apply foam around your closet doors. The clothes themselves act as an aid to minimize the sound waves. Having cushioned furniture like sofas also will add to noise resistance. If you have noisy neighbors adjacent to one of your walls, consider applying wedge foam panel right there and get rid of the crazy daily brawl. You can buy wedge foam panels with a pattern of 12 x 12 inches or 24 x 24-inch panels depending upon the requirements.
      3. Now coming over to the doors and windows. Make sure the panels around them have rubberized foam which blocks most of the outer noise by creating a proper seal when closed. If there is still a gap below the door, consider applying door sweep.
      4. If you have a hard cemented floor or timber floor, you always need to put down a rubberized layer, some more layers made of cork and a lot of glue underneath in order to make your room soundproof. But the process drains a lot of money from your pocket. But don’t worry, loose lay is a new vinyl flooring product specially engineered to enhance the acoustic properties while saving lots of money.

And now at last, if you’re worried to notice the cracks within your soundproof adjustments, here is a quick fix. I have come up with Noiseproofing Sealant Seals which is an extremely useful product. It is super easy to apply and takes around 48 hours to completely dry. It is a non-toxic glue and lasts long without any cracks. It also adds up to blocking the noise significantly.
Movie time:

Comparison between before and after soundproofing
Suppose there is a classroom, big enough to accommodate 20 students. We can hear the mixture of different noises like discussions, moving chairs, stationery sounds, sound reflection from other classrooms, etc. These noises reverberate continuously across and within the walls. This might be a disturbing factor for the teachers as well as students.
On applying the soundproofing solutions in the class, 90% of the external noise gets reduced. Now, if we look inside the classroom, we have similar noises in all the class activities. This time, the sound stops reverberating significantly. We will no longer hear the disturbing echoes all the time as most of them get absorbed by the soundproof walls. This makes us more readily acceptable to the environment, concentrate on the work, and have a comfortable stay.

Conclusion
We came to know that sound travels between rooms in two ways: through the structures and through the air. We definitely don’t want to get disturbed by all such factors and ensure to have a happier and peaceful stay at home. Most people are reported to get annoyed or irritated by continuously hearing noises. Therefore, some of the reasons that are really important for sound insulation are privacy, insulation from the neighbor house, recording or singing practices, and uninterrupted sleep.