What Are The Best Sound Damping Materials & How Do They Work?

What Are The Best Sound Damping Materials & How Do They Work?


Hi everyone, I’m Dennis Foley from Acoustic
Fields. Today we’re going to talk about sound dampening materials versus sound absorbing materials.
These terms are used interchangeably and they’re really not. They pertain to completely different
things, completely different concepts and mechanism; related but really different and
there’s a lot of confusion in it. Let’s try to clear some of that up today.
Sound dampening materials, the operative word here is dampening. Dampening is really a vibrational
term. We damp vibrations. Remember the rock on top of an amplifier? It got better sound,
well it got different sound because that’s an electromechanical system and you put some
mass on it, you change the vibrational signature, sort of speak of the unit. Damping is a process
that’s relegated to vibration and the science of vibration. Damping is a process we use
in barrier technology. When you build a real nice recording studio, you have 2 rooms really
within one room. You have the inside room, which is where you use your sound absorption
and sound diffusion treatments and you have an exterior shell, which keeps the noise from
the neighborhood and surrounding areas out, keeps the base drum and guitar and electric
guitar from coming out of the studio also, hopefully. Damping is a vibrational term used
in vibration. We want to keep those 2 separate but distinct.
Really when we’re talking about, instead of saying sound damping materials, we should
say, and people think that sound damping means sound absorption. It does not. Sound absorbing
materials should be called sound absorbing materials and sound attenuation is the process
whereby you use that sound absorption to reduce the energy levels but sound damping and sound
absorption are different, very, very different and let’s look how.
Let’s use an example to illustrate sound damping. We discussed the 2 rooms that we have really
in our studios that we build. We have the inside room and then we have the outside shell.
The outside shell is really the barrier between outside noise coming in and inside noise going
out. In that barrier technology, we use a lot of times multiple layers of materials,
multiple layers with different densities. Why? Why different densities? Because what
we’re trying to do is trick, if you will or fool, to apply human terms to it. This huge
pressure wave that the bus outside or that garbage truck has produced and this wave is
headed into our studio. How are we going to stop it? The quickest way to stop it is through
an erected barrier, between it and us. The barrier has to be selected based on frequency,
space requirements and obviously budget. Barrier technology is very expensive. It can go $350,
$450, $550, $100, $550 a square foot in some cases. Barrier technology, keeping unwanted
noise out is very, very expensive to do and to do it right, especially if you have low
noise requirements for the room you seek. How do we do that? How do we do it in the
best way? Obviously we want to achieve the most impact in the smallest amount of space
and obviously not have it weigh very much. Well we can’t satisfy all those criteria so
it’s going to weigh a lot. We use multiple layers and the layers of materials that we
use have different densities and that as a vibration, if you’re a vibration or a sound
energy wave striking this surface and you encounter one density, it’s going to distort
your wave form X. When it strikes a material of another density, it’s going to do X plus
that material. When it strikes another material, it’s going to do X plus that material. It’s
this series of materials that the energy wave has to go through so that it’s reduced in
amplitude on the other side. There’s actually a name for that process. It’s called constrained
layer mass damping. I know that’s a mouthful but basically it’s the arrangement of materials.
It’s the choosing of densities. It’s the arrangement of those materials with those densities that
causes this huge wave to be reduced into something that’s not so bothersome or troublesome.
Damping technology is really associated with vibrations and we should really keep it in
that domain. Sound absorption technology is really that. It refers to the process of absorption
that’s converting to heat. Damping really refers to vibrational control.
Thank you.

27 thoughts on “What Are The Best Sound Damping Materials & How Do They Work?

  1. How do real movie theaters barer sound were can't here the other room at all and they may have a loud movie with subs Gowing down to 23cycles and in the room next you would never know

  2. Hey, I'm making my room sound proof for video/audio recording. But its on a road with heavy traffic. Can two layers (One of 1.5" foam + thermopore sheet) can block the surrounding noises?

  3. Hi! Is it possible to achieve something similar without building an inner and an outer shell? I own an adjoining flat and I can hear my neighbor quite clearly, specially his doorbell. I assume damping is the way to go, but building a room inside the living room would be costly, so I should somehow treat a 2.5 by 6 m wall instead. Could you adress this subject anytime soon? I've been waiting for something like that but, as far as I've seen, your videos always focus on absorbing/diffusing/damping interior sound sources. Thanks!

  4. What material deflects sound without vibrating such as acoustics? I want to deflect it back my direction so I know to use a parabolic curve or circle with the material.

  5. Give your video a less misleading title, please. We're looking for an in depth description of different materials and their helpfulness, not a lesson on terminology.

  6. I REALLY appreciate your detailed explanation on a field that is SO little understood even by professionals.
    I am primarily a musician who at some point decided to build my OWN recording studio in a family neighborhood.
    I was fascinated by the physics of "sound" and by the utter ignorance of "sound professionals" regarding sound.
    These were the types that put egg crates on the walls or covered the studio with VERY expensive soundex glued to a piece of 1/4 sheet rock . The physics of sound totally absent from their very limited knowledge. Fortunately my first book on studio design contained a DEEP understanding of psycho acoustics and explained IN DETAIL how a poor wall treatment could increase certain frequencies from 50Hz down to subsonic harmonies. I do not know if you recall a popular gizmo that promised the deepest sound you could get in a room WITHOUT speakers. These were plates applied (glued) to walls that could put the walls into sympathetic vibration and the walls acted as the cone of a speaker with frequencies so low they would make you sick. The ONLY benefit of this invention was to tune the plates to achieve phase cancellation on some frequencies so that a different number of damping would not be needed. Before that you had to sandwich layers of panel of specific acoustic resonances to kill a range of very low sounds and it was a mathematical formula that will guide you to the thickness and material of each layer AND the distance between . Since getting exactly what the formula called for many time I had to go for trial and error on the other side of the wall I wanted to dampen. But the "Sound plate" was a quantum leap in sound applications . Put ANY sheet rock wall place plates around it , a mic behind and fire your frequency . By tuning THE WALL you'd see the offending frequency drop at the turn of a knob . This was a god send to engineers , BUT it was a tool of destruction to people at home who wanted to crack the walls of their neighbors.
    Do YOU recall this invention and if you do , what the hell ever happened to it?
    Thanks – great series … but complains are mainly voiced by less than neophytes so do NOT loose hope. To some of us this not only brings great memories but a yearning to go back and experience all the new technology that was available and made us magicians , masters of sound.
    🙂

  7. so professor . what is the best material for sound adsorption. my roommate is sound and i need to reduce those noise when studying

  8. If all you want to do is reduce sound pollution so you can record audio podcasts in a small 5×5 space, what would you recommend for a solution under $1,000.00?

    I already bought a 6 pack of the producer's choice acoustic blankets that are supposed to arrive tomorrow. It seems that most of the sound pollution in this environment comes through the door, so I'm considering ordering the producer's choice door covering also, but I want to first see what I'm working with when the blankets arrive.

    I also bought one of them cheapie $40 microphone sound isolation booths and adhered some mutex to the outside of it. I don't think I'd recommend this approach to anyone by the way. Money would have been better spent on the frame for the blankets or put towards the door cover I'm pretty sure. Anyway..

    Although the blankets have a 0.8 NRC they're not going to be able to deal with low frequencies, and even in the mid to upper frequencies they're only going to offer something like 10 db reduction with a single layer. Some of the challenges in this environment consist chiefly of dog barks, dogs playing, dogs walking across hardwood flooring.. but basically the dogs barking in the 1K – 2K frequency range isn't the issue, it's the 60 – 110 db they're capable of producing that is the issue.

    I don't own a home or have an office and I certainly cannot afford to go all out and build a room within a room.. I know I cannot have a sound proofed environment, but is there something I can do to give myself another 20 – 30 db of noise reduction for only another $200 – $300?

  9. You kept saying the terms are "very very different" yet if there is a difference, it is not apparent you know what the difference is.
    Sound IS vibration. Absorption does result in damping.
    Did you actually feel good about this video? What useful information did you hope you had conveyed?

  10. Mr. Foley(sp?) I appreciate these videos. You get pretty in depth although I wish you had the time to go even more in depth as in a “class” on acoustics. However I do notice that you are very scientific in the way you deliver information by making note of all the grey areas and nuance in the subject matter. Making sure that the audience realizes this is not cut and dry. Although I usually love that approach across the board in any field, ie: nutrition, Psychology, what have you, there comes a point where I really wish you might just throw out some broad general guidelines or advice for maybe at least a handful of scenarios. As an example you might say, “If you were playing drums in a garage and didn’t want any noise complaints you may want to have a separate room within a room or multiple layers of drywall with cotton insulation. Etc. etc. something to that affect. Hopefully what I’m saying makes sense and maybe there is some basic fundamental material(s) that you could safely say will do “x” relatively consistently when used in scenario “x”. Thanks for the free info

  11. I have a question. Would composite asphalt shingles act as decouples if sandwiched between two pieces of 2x10s or sandwiched between two pieces of sheet rock?

  12. Thanks for sharing all of your knowledge. I find your videos to be super helpful.
    I’m going to be trying to make a budget home studio. I’m planning on adding a second layer of drywall with green glue to my existing walls as well. But before that, I want to blow in some insulation. Do you have a suggestion? I heard fiberglass is best because it is lighter and won’t transfer as much low end energy. But cellulose seems to be what many people are using. On a tight budget. Any help is greatly appreciated. Thanks

  13. Thank you for a wonderful video, and for excellent communications when I contacted you for advise.
    Keep on the amazing work!!!

  14. I have a block factory close to neighbors, they are not complaining yet about the vibrating noise; however, is there anyway I could do something to my fence to reduce that noise to reach them? What can i do?

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