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Thread: General confusion over polystyrene

  1. #11
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    "I was actually surprised by the relatively low absorption coefficient of sand."

    I think you are still confusing 'Absorption' with 'Obstruction'? A sand filled wall will have a very high mass, just what you need to stop sound travel. You can get EXPS clad with 3mm Hardboard and this is really a good sound proofing material of low overall weight. Not as good as plasterboard but easier to handle and can be portable.

    Generally: If 'it' is dense and dose not move, stops sound. If 'it' is light and moves, absorbs sound.
    If it moves and EMITS sound? Salute it.

    Dave.

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    Quote Originally Posted by spitzer View Post
    I'm not sure that logic is completely valid. One of the reasons for my asking this whole thing is precisely that there are VERY few smart people who actually have worked anything out scientifically. I've read countless posts on forums saying the equivalent of "don't use polystyrene because of the fire hazard". That's everywhere. On the other hand, ANY explanation of whether or not, or WHY would it not work in conjunction with fiberboard to block, absorb or scatter sound waves... that information is nowhere to be found.
    So then, by your logic...anything/everything that has NOT been clearly tested for acoustics, should have the potential to be good for acoustic treatment...???

    I actually did give you a simple explanation that went beyond the "fire hazard thing". Styrofoam is closed cell foam...which HAS been proven not to be all that great for acoustics use. It's terrific for hot/cold insulation, but not much else. Things like fiberglass, etc...is open fiber construction, which dissipates sound energy into heat energy. That is how it works.

    The simple point is this...you can knock yourself out and experiment with anything/everything that has not been formally tested (which is your logic)...or you can simply use the materials that HAVE been tested, and are known to be good for acoustic treatment. That goes in both home and pro studios.

    Maybe there's a better way to make a wheel...?

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    Yes, open cell foam is the best absorber. PS foam generally isn't.

    A good acoustic foam will have high open cell content, high loss tangent for the matrix polymer, and high density. The surfaces need to be skived (skinned off) to minimize reflection, and cell sizes need to be relatively large, on the order of a couple millimeters. I've experimented with foaming some damping rubber compounds and am currently working on a 2K polyurethane system with a visco PUR.

    For sound blocking, mass and hermetic seal are the two most important factors.

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    Quote Originally Posted by miroslav View Post
    So then, by your logic...anything/everything that has NOT been clearly tested for acoustics, should have the potential to be good for acoustic treatment...???

    I actually did give you a simple explanation that went beyond the "fire hazard thing". Styrofoam is closed cell foam...which HAS been proven not to be all that great for acoustics use. It's terrific for hot/cold insulation, but not much else. Things like fiberglass, etc...is open fiber construction, which dissipates sound energy into heat energy. That is how it works.

    The simple point is this...you can knock yourself out and experiment with anything/everything that has not been formally tested (which is your logic)...or you can simply use the materials that HAVE been tested, and are known to be good for acoustic treatment. That goes in both home and pro studios.

    Maybe there's a better way to make a wheel...?
    Miroslav... there's no need whatsoever to be so spiteful.

    By "my logic"? What are you referring to? What I said boils down to: Just because "no one" does something, does not mean it does not or CAN not work. Similarly, there is absolutely no guarantee that if there's something already existing, someone or "everyone" would have found out what exactly it is and what are the possible uses for it.
    Haven't you ever seen MacGyver? The point of that show is not that everything can be used to do everything, but instead it shows situations where you are forced to actually THINK how stuff actually works and whether or not some, whatever completely off the wall crazy thing COULD work.

    I don't understand your constant conjecture. No one here said they want to "reinvent the wheel" or anything like that.

    P. S. In the past, in another discussion, it took a long, long time for anyone to confirm my belief that a certain energy can not co-exist as BOTH sound and heat. That is VERY obvious to me. Do you feel there's a problem with my logical skills and if so, why?

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    Quote Originally Posted by ecc83 View Post
    Just saw you claim the stuff works as a treatment? I would say that is because a panel will be set in motion by the sound energy and in its tiny flexings dissipate some sound energy. I am confident a solid, rigid block of the same overall volume will act more 'brick-like'.

    Should be easy enough to do some before and after recordings? Just need a waffle into the space.

    Dave.
    The situation where an EPS sheet seemed to work as "treatment", although it's impossible to tell whether as a reflector or absorber (pure guess: both), was in a hard walled cavity holding the sound source. Aka echo chamber. As it was, it was difficult to understand speech, for example, as the sound bounced around. A small piece of EPS next to the source made a HUGE difference (the REALLY annoying echo was almost completely gone), and I suspect lining all sides would be even better.

    Before/after recordings of this particular thing would actually require quite a bit of work... but I doubt it would be interesting. I once made that sort of A/B thing with numbers for different frequencies, showing you could make an effective low freq blocker/absorber from a shoebox and a doormat... guess how many gave a crap

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    Quote Originally Posted by spitzer View Post
    Do you feel there's a problem with my logical skills and if so, why?
    The problem is that you set up a premise...that requires negative logic to prove something is true.
    That's my problem...and when people insist on dismissing known facts and best practices, because they don't fit their personal expectations or beliefs.

    You know what...just ignore my attempts at providing you with actual facts...and then go put up the Styrofoam, because NO ONE here is going to run out and do extensive testing for you, to prove that it's a lousy acoustic treatment choice (not to mention the fire hazard)...so just do it yourself, and be satisfied.

    I really don't want to waste my time with this.
    If people are here because they are looking for true solutions, and just need some guidance so they can got on with their studio construction and treatment...then I'm more than happy to be part of the conversations. I don't care about stuff that is well off the beaten path, because the science of audio and acoustics is not something we need to reexamine and reinvent here. It's quite safe to just accept the norm, and then get on with the business of making music, if that's what your goal really is...and I wonder about that sometimes here on the forums, because it seems like some people are just here to banter about topics, bot not so much to actually do anything with recording music.

    Good luck with the Styrofoam.

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    The thing here that is the constant and only rule is physics. Conservation of energy. Converting one form of energy into another. This is why there is no need to test products to predict basic behaviour. You can do the prediction simply. You need to test to determine how exactly the conversion performs, but you know something works or won't work - the variable is how much?

    Polystyrene has very specific features. Its thermal performance is well know - to the touch it's always warm, but it's very hard - especially when cut via heated wires that cut and seal by melting the surface. Formed building foam being rougher on the outside than packing foam. Physics lets you determine that one will reflect similar to a hard panel, and the other will difuse because of the number of slightly different angles. The hard surfaces absorb very little and the polystyrene takes up very little of the sound energy as heat. On soft foam, the proportion of sound converted to heat is higher, but we know this is frequency dependent - bass goes right through largely unaffected, HF getting the heat conversion. A membrane absorber is quite hard, which should reflect, but it moves, and the sound is converted to kinetic energy - the vital bit being there's less sound left! Polystyrene because if the lack of mass/weight won't allow this conversion.

    As an audio inexpert, my level of physics lets me predict the basic functions but I cannot quantify it, but I can understand what is happening. Plasterboard vs MDF is a good one. Plasterboard seems a good audio product because of how it responds to sound - some reflection, some absorbtion, plenty of mass, but MDF has a hard sealed surface, so has mass and reflection properties. How does painting plasterboard impact on the figures and performance? Don't know from doing it. Acousticians can read and really understand the specs. Less able people like me can only understand the lower tier of data. Good to learn though!

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    Quote Originally Posted by rob aylestone View Post
    How does painting plasterboard impact on the figures and performance? Don't know from doing it. Acousticians can read and really understand the specs. Less able people like me can only understand the lower tier of data. Good to learn though!
    On a similar point...I've been preparing wood panels that will be spread out on the walls of my new studio (you can see details in my studio documentation thread)...some of it for aesthetics, as I do not want just the look of painted drywall...but also for acoustic treatment purposes, since the wood panels are on the rough/porous side.

    Someone asked me if I was going to paint them...I said no, they were going to be only stained, and then no poly of any kind...so I could maintain the porous condition. If I painted them or added a poly finish over the stain...they would not be much better than the drywall for acoustics, and would only serve the aesthetics.
    The panels will also get a liberal amount of elastomeric caulking between them and the drywall before I screw them to the walls...which will help deaden any vibrations and also for some additional sound reduction.

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    Quote Originally Posted by miroslav View Post
    The problem is that you set up a premise...that requires negative logic to prove something is true.
    That's my problem...and when people insist on dismissing known facts and best practices, because they don't fit their personal expectations or beliefs.
    That is indeed YOUR problem. Precisely no one on this entire thread has done what you're describing here.

    Quote Originally Posted by miroslav
    You know what...just ignore my attempts at providing you with actual facts...and then go put up the Styrofoam, because NO ONE here is going to run out and do extensive testing for you, to prove that it's a lousy acoustic treatment choice (not to mention the fire hazard)...so just do it yourself, and be satisfied.
    Go "put up the styrofoam" where? What styrofoam? I have not ignored any "actual facts", I just honestly don't understand roughly 50% of what your replies are about. You're answering stuff NO ONE asked in the first place.

    It's EXTREMELY difficult to tell if you're indeed actually trying to be helpful. Honestly. I do not know.

    Quote Originally Posted by miroslav
    I really don't want to waste my time with this.
    If people are here because they are looking for true solutions, and just need some guidance so they can got on with their studio construction and treatment...then I'm more than happy to be part of the conversations. I don't care about stuff that is well off the beaten path, because the science of audio and acoustics is not something we need to reexamine and reinvent here. It's quite safe to just accept the norm, and then get on with the business of making music, if that's what your goal really is...and I wonder about that sometimes here on the forums, because it seems like some people are just here to banter about topics, bot not so much to actually do anything with recording music.
    Then DO NOT reply! Is that too difficult for you? If you don't want to "waste your time", then DON'T.

    Different people have different interests and different viewpoints. I personally DO care about stuff "well off the beaten path". If I was actually suggesting that I would actually build a studio and ACTUALLY use styrofoam in place of rockwool, I WOULD HAVE SAID SO. However instead, i specifically said this was a scientific type question.

    Also, I indeed am just here to banter about topics. Making music, playing music, recording music is what I do regardless of anything else. I could post a thread here asking do you like your coffee black or with maple syrup in it. Who ever said everything here would need to be directly (and personally???) connected to "recording music"? This is just a forum. Just. A. Forum.

    Quote Originally Posted by miroslav
    Good luck with the Styrofoam.
    ... (be nice, please.)

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    Quote Originally Posted by miroslav View Post
    On a similar point...I've been preparing wood panels that will be spread out on the walls of my new studio (you can see details in my studio documentation thread)...some of it for aesthetics, as I do not want just the look of painted drywall...but also for acoustic treatment purposes, since the wood panels are on the rough/porous side.

    Someone asked me if I was going to paint them...I said no, they were going to be only stained, and then no poly of any kind...so I could maintain the porous condition. If I painted them or added a poly finish over the stain...they would not be much better than the drywall for acoustics, and would only serve the aesthetics.
    The panels will also get a liberal amount of elastomeric caulking between them and the drywall before I screw them to the walls...which will help deaden any vibrations and also for some additional sound reduction.
    Now THIS is interesting, and incidentally something that I researched (or tried to) a couple of years back. I also don't like the look of painted drywall. I also THINK I don't like the SOUND (reflections) of painted drywall. A million people told me that unpainted aka porous wood would sound the same as a painted wall. I flat out refused to believe them.

    What's the "additional sound reduction" you're talking about there? Reduction through the wall?

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