Anyone Have Experience With Low Frequency Soundproofing?

Also if you have access to over top your ceiling 1/4" of play sand absorbs any sound, in or out!

I can sympathize with you about low frequency noise. High frequency noise can easily be attenuated. Basically, you live inside a loudspeaker enclosure. The walls of the box resonate in concert with the frequency applied. In order to reduce the walls from resonating, you make the walls stiff/rigid so they don't vibrate. I once built a loudspeaker enclosure that had double walls filled with sand. The only sound that reached me was directly from the loudspeaker. the walls were "dead". This is the only way to stop vibration from resonator sources, like exhaust pipes or boom-boom car speaker systems. The walls of your house have to be made rigid so they don't resonate. This is obviously not possible. Changing windows to triple pane may help a little, but unless the large wall expanses are dealt with, you will never eliminate the low frequency noise completely. Even a very small amount can be heard (or even felt). My house is a quarter mile from the road, but every time a car goes by with one of those boom-boom sound systems, I can hear and feel the vibration through my walls. My neighbor had one of those systems until I told him to quit. As someone else mentioned, shrubbery of some kind can help to absorb some of the noise. A concrete wall between your property and his could be built, but the sound might just bounce off his side of the wall, then bounce off the side of his house and be directed towards your house.

Actually, making walls rigid just increases the frequency that the walls resonate at. It works to some degree, but does not really dissipate the acoustic energy.

The layer of sand, although impractical for house walls, is an excellent material for dissipating that acoustic energy by converting that energy into heat.

The Green Glue between two layers of drywall, as I mentioned at the start, does the same thing by creating a constrained layer. In fact, Green Glue was developed exactly for this situation.

I have a number of tubes of that stuff waiting to be applied to my loudspeaker cabinet walls to dampen the vibration.

I really don't know what kind of windows the original poster has, but I would bet that they are the larger contributor to the noise.

Speaking of concrete barrier walls to stop noise... I know of a highway where they did that to keep road noise from the highway down. They built two walls and the result actually made the problem worse, not better.

Speaking of concrete barrier walls to stop noise... I know of a highway where they did that to keep road noise from the highway down. They built two walls and the result actually made the problem worse, not better.

I've noticed the same thing in California where they build high walls around communities adjacent to heavily travelled roads. It may attenuate the sound in some areas, but may accentuate it in others. I guess it depends on the frequencies. Much too complex for a simple answer.

It has everything to do with reflections and refraction. Acoustics is not a simple subject as I found out a few years back.

Most of the replies I read suggest means that will cost you money and/or modify your home and/or personal behavior. To this I say NO WAY. It is your life, your property for you to enjoy without having to compromise for inconsiderate neighbors. A few mentioned delivering a polite letter followed by complaints to the PD and finally the services of a lawyer. Although this may entail some cost, I think it is the best advice. The enjoyment of your property is a basic property owner's right. I condemn any idea of causing damage to his property. That is illegal and makes you no better than him/her. Replacing windows is very expensive. I would not consider that as a solution. Nor would I hang vinyl curtains, nail egg crates to the walls or increase the drywall thickness. To me there is only one way and that is the legal approach. I know the frustration you feel. Some don't seem to be bothered by it. They make concessions where they should never be made. Stand up for your rights. Don't let others s--t on you.

I've been reading and this is a difficult problem. Or move, or go to store and buy some Belgian Beers, Duvel(=devil) Pirate, Belzebub. 12% vol. is to suppress muffler sounds. These are designed for such problems. Side effects are mild.

Is it worth it to you to remodel your bedroom? I would suggest removing your sheetrock and windows, applying expanding spray foam insulation, replacing sheetrock, replacing windows with vinyl frame-double pane insulated windows, (borders well insulated with same material) and getting a good nights sleep. It may not "soundproof" the room, but I'm pretty sure it would reduce it so much that you could sleep through till your alarm goes off.

The only other thing I can think of at the moment is a segment I saw on tv once, in which a fellow wanted to build a music studio in his house. The show's professional showed him how to build a second "false" wall in front of but not touching (or minimal) the supporting wall, so that he achieved a major dampening of the transmittal of sound waves through the studs. They filled the gap with insulation, but don't remember what kind. I would say that expanding spray foam (one brand I've been looking into is Icynene) is probably your best bet.

I know what you mean with those low "rumbling" frequencies, hope you find this helpful. Let us know what you decide.

I've built these walls. The trick is to stager the studs on a larger plate so that when the sheetrock is nailed to the studs the two halves of the wall float with respect to each other.

Fiberglass batt insulation is woven in between the the inner sections of the two walls to reduce internal standing waves and resonances.

The foam is a bad idea and very expensive and it will couple some of the vibrations from the outer wall to the inner wall, thus defeating the idea of isolation.

The whole idea is poor because it involves the owner paying a lot of money for a solution to a problem someone else is responsible for.

While it's technically fun to ponder solutions, the best solution is stoping the problem at the source. The neighbor needs to either put OEM mufflers on his truck or park it somewhere else.

Frankly, it is rude and wrong to modify your vehicle for your own pleasure when it negatively impacts the harmony of others. The neighbor should correct the problem.

Good, someone else knows what I'm referring to. I know the insulating power of that expanding foam, noise and otherwise, and I'm still gonna go with that one as a best bet. And you can be SURE it's a darn sight simpler than staggering studs like you talk about. Now this is just the opinion of a DIY'er, and I understand there are as many different opinions as there are, well...

A simple wall is just that. Simple. And I'd spend a weekend bbq'ing, drinking a couple beers with my buddies, putting in a simple wall or two way before I'd go making enemies with my closest neighbors, especially 60 year old ones. I'd even ask him to come and help, maybe he could tell some war stories or something...

A sleeping chamber is cost effective by comparison though...

What is a sleeping chamber? How much does that cost?

It's like a pod or personal sleep environment; you can DIY one... example.

http://www.articlealley.com/article_503250_27.html

I've built something similar.. but the intent was different. How exactly do you make it soundproof? I used styrofoam and Coroplast.. I think it might actually amplify.

Not unlike the construction of audiometric test or iso booths. What do you hear in the background?

thanks for the pdf. I don't understand the pattinson link?

They're in an isolation booth which is inside an arena as an event is on going outside of the booth while they are inside recording an interview. It's the raw feed you are listening as the audio is muted both within and out. Silent kinda.

gotcha.

The problem with the expanding foam is that it is somewhat rigid which means as one wall moves it will transfer some of the energy to the other wall, whereas batt insulation wont. The stuff is great as thermal insulation, but as sound insulation it is not so good.

Generally the most difficult aspect of high level isolation is controlling the low frequencies (bass). Keep in mind that STC doesn't measure bass, as it does not consider frequencies below 125Hz, and we're obviously dealing with rooms that put out a great deal of sound below that. Generally construction efforts to reduce low frequencies will naturally take care of the lower energy high frequencies.

In short, every compressible cavity (such as air cavities in walls and ceilings) will define a specific resonance point (frequency) in a decoupled system. If we have a double stud wall, or ceiling with clips and channel, then we have a decoupled system. Think of this decoupled system as a spring that oscillates. This system will have a calculable low frequency resonance point, defined by the Mass-Air (spring)-Mass parameters. Let's say this resonance point is 70Hz.

At 70Hz, we don't stop a lot of sound, since resonance allows that frequency to pass fairly easily. At 100Hz, we're doing much better, but as we start looking at frequencies lower than 100Hz, Transmission Loss gets worse and worse until we hit 70Hz rock bottom. So at resonance (70Hz), and just above resonance (70-100Hz) things are not great for our sound isolation. Generally the math is from the resonance point up to around 1.5X the resonance point we don't do as well in sound isolation.

If we could move that resonance point from 70Hz. to 40Hz. we would be much better off:

Scenario #1 has 70Hz resonance point, and weakness from 70Hz through 105Hz. (70 x 1.5= 105).

Scenario #2 has a 40Hz. resonance point, and a weakness from 40Hz through 60Hz. (40 x 1.5= 60).

This is why we spend time looking to incorporate methods to lower that LF resonance point as much as possible. How do we accomplish this? Keeping in mind that a decoupled system is a spring system:

We can add absorption in the form of simple (standard thermal) insulation. This will lower the resonance point (frequency) of the system a bit.

We can add mass to the system. This essentially weighs down our spring system, slowing the oscillation = lowering the resonance. The added mass is more effective than the insulation.

We can add cavity depth to the system. For the same reason that insulation helps, so does more air in the cavity. This also isn't as effective as adding the mass.

So again, if we can progressively march that low frequency point down, we minimize the frequencies that will display weakness.

Hope this helps. .

Lowering the resonance point is essentially making the system more compliant. This is counter to what you want to do.

In loudspeaker design one method is to raise the box wall resonance. Why? Higher frequency resonances generally have lower energy and are easier to attenuate. You never, never want to lower box wall resonance. I'll explain why shortly.

To raise the loudspeaker wall resonance you would add wall-to-wall bracing or increase wall thickness and/or subdivide the wall panels asymmetrically into smaller panels with bracing. Other methods include adding mass as an energy absorbing technique (i.e., roofing felt, damping rubber mat, etc.), adding an absorbent dense fiberglass material (i.e. Rockwool), or constrained layering.

I am clueless about the 1.5 constant you use to multiply the resonance point by. It looks like a crude mechanism to describe the Q of the resonance point, which is typically pretty steep.

Regardless of the resonance point, there will also be 1st, 2nd, 3rd, and so forth, resonance peaks that are harmonics. For instance, if you have a 70 Hz resonance, you also get a 140 Hz, 280 Hz, and higher multiples from the fundamental resonance.

This is another very good reason why you would not want to lower the wall resonance because you are increasing the number of harmonic resonances as you decrease the fundamental frequency.

Instead of 70, 140, 280 Hz... you could have 20, 40, 80, 160, 320 Hz... Obviously, this exasperates the situation.

There are several websites such as the one I previously linked that have all of this raw data for anyone to look at.

When we deviate from a single leaf mass like a solid rock wall, we introduce an air cavity that resonates. The resulting new mass-air-mass system will have a characteristic improvement in the Transmission Loss of the upper frequencies and a reduction in performance in the lower frequencies. Here's another classic study done by the NRC in Montreal http://www.nrc-cnrc.gc.ca/obj/irc/doc/pubs/ir/ir761/ir761.pdf

The position of that Low Frequency resonance point is defining, and the lower it is, the better the low frequency isolation. Check the data

If we tune the resonance point of the wall system higher in frequency as you suggest, you will simply be sequentially reducing the low frequency Transmission Loss of the wall as you move the resonance point higher and higher.

Note that a single stud wall with a resonance of 125Hz may gave an STC of 33 and terrible low frequency isolation below 125Hz.

On the other hand a decoupled double stud wall will have a much lower resonance point (perhaps 40-50Hz) and much much better low frequency attenuation.

There are several dozen test reports on that site and many others like it.

368 pages and not once is the word "resonance" used in the document.

I do not see anywhere in the document that supports your claim that lowering the resonance of the wall improves performance of the transmission loss.

Please provide definitive citations to back up your claim (document link, page number, etc.).

Vance Dickenson's Loudspeaker Design Cookbook, 7th Edition, section 5.40 states the exact opposite of what you are thinking for reducing transmission of sound through the walls of a box. Vance states that raising the resonance frequency is what you want to do. Mechanisms to do this included, but were not limited to, stiffing the wall material or subdividing the wall panel into smaller panels to raise the panel resonance point.

I can not imagine that a room is really any different than a loudspeaker box.

As far as gypsum walls are concerned, increasing the layers or gypsum thickness reduces the transmission of sound. Your cited document supports that claim. If you were to knock on the surface of a thin gypsum wall versus a thick gypsum wall or even a concrete wall you would hear increasing frequency as thickness or density increases. As panel resonance increases in frequency so does transmission loss at lower frequencies. So I think you just have it backwards in this instance.

I wonder if you are interpreting those graphs incorrectly? Are you thinking that the minimums of the graph is the resonance of the wall? The minimums on the graph only represents the least transmission loss for that specific frequency. It does not tell us anything about its resonance point, only that it is fairly acoustically transparent at that frequency.

Single Stud Wall Page 23

Test TL-93-175

Low frequency resonance point at 125Hz.

18.2dB of Transmission Loss at 100Hz

Double Stud Wall Page 318

Test TL-93-273

Low frequency resonance point somewhere around 50Hz

26.8dB Transmission Loss at 100Hz

Thanks for the link. Now I understand.

Those frequencies are simply the frequency that the transmission loss is the lowest, it does not necessarily represent a resonance of the wall material, but resonance of the cavity and wall as a system.

Pages 25 and 26 illustrate better what increasing wall thickness does. Notice the slightly better low frequency response with wall thickness. This is more representative of my point.

Page 27 shows what happens with a different stud material and 28 changes the stud to stud center distance. This illustrates that the wall is more than just wall material and thickness, but works as a system.

Distance between centers has a strong correlation between the minimums in transmission loss. The greater the stud distance, the lower in frequency is that minimus. Dividing the panels into smaller sections raises the panel resonance point and the minimum transmission loss frequency. This effectively stiffens the wall and blocks lower frequency sound a little better.

Yea, the solid wall of a speaker and the wall of your house differ primarily due to the air cavity. The air cavity helps us or hurts us depending on the frequency we're looking at.

The frequencies I'm referring to are known as the Low Frequency resonance point. Also known as the Mass-Air-mass resonance point or the Mass-Spring-Mass resonance point. As you say, the LF resonance point is the result of adding a second leaf (and therefore air cavity). A solid mass has no such resonance point.

Again, it is the resonance point of the system, not the individual materials that defines low frequency isolation potential. The materials do have a Coincidence Point. This is the frequency at which the bending wave travelling through the panel is the same speed as the sound wave through the air. Both incident waves are co-incident. Note that isolation also suffers as we approach coincidence.

The coincidence point of 5/8" drywall is like a fingerprint at 2500Hz, while ½" drywall is 3100Hz. In a decoupled system however, these points do not figure into the low frequency resonance point calculation. The mass does.

Increasing the cavity depth (wall thickness) is one of the factors I listed that will march that LF resonance point down.

Increasing the span with 24" OC studs vs. 16" OC studs reduces the vibration conduction points (fewer studs = less conduction). The bigger issue however, is the increase in panel flex in a 24" OC wall. All things being equal, a 24" OC wall frame will perform better than a 16" frame, primarily due to the flex. A 16" OC 25 ga. steel stud wall will perform better than a comparable wood stud. The steel flexes more, and the wall isolates better despite the fact that it is of lower mass. So stiffness in fact does not help us. It hurts us for transmission loss.

By the way the 1.5 figure is simply a rule of thumb. If you look at the LF resonance point and multiply by 1.5 you'd see that's where the TL starts to drop precipitously

I don't know if you have access to panels, that are made of long basts of young twines, and cement? They are about 3 inches thick and come with tooth and groove. They are pretty cheap and solve most problems for frequencies between 500 and 35 Hz. We used this as semi- hanging walls or walls on rubber in dancings in a street row and before building dead room structures and sound studios. Is a fraction of lead containing sheets or panels and not a problem for environment, pests. They are also good for center piece between separation walls in buildings. Ridgid, heavy and a good base to dot glue sheet rock on. Is a lot better than a brick wall and can be used for ceiling (floor), walls and floors. They come in different densities and acoustically the rooms are scary dead already. When the vibrations are entering the building through the floor and structure, you'll need to do also the floors. When you want to use this, there are some tricks to it.

Hi, guy, I have the similar experience as you before. My upstairs neighbour used to switch on TV and hifi loudly, worse still, he has two annoying dogs that barks during all the time. I also have tried for many soundproofing methods before. The situation has little improvement till my friend recommended Green Glue to me. This is a soundproofing compound that is used in between two layers of boarding materials like gypsum board. Its soundproofing performance is really impressive. It is capable of eliminating low frequency noise and the soundproofing wall structure is much thinner than other solutions.You can apply it on a DIY basis as the application is really easy and fast. If you can interested in it, please send me a PM and I can send more information to you.

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