Please have patience 
Has anyone investigated this much, with regard speaker enclosures? Had a search already and though people thought it wouldn't work (due to water allowing waves to travel within it easily) I know it's hardly the most practical of things to work with, especially with lots of electricity flowing round.
Anyway got me thinking about using something like those fillable ice cube bags (obviously not frozen and eventually designed specifically to be more durable) as sound deadening on the internal walls of a cabinet. Basically a cellular material with water (or maybe a gel?)in the cells. Imagine big bubble wrap but filled with water instead. I agree that a layer of water sandwiched between two walls would allow the rapid and efficient transmission of waves between the sandwich materials. However I have a feeling that by housing the water in flexible cells which are not physically fixed to the walls (maybe, say, hung from the top) the waves may be dissipated without being transmitted to the cabinet walls. Kind of like a hydro suspension kinda thing... imagine punching a water bed (bad analogy but the best I can come up with).
I know it will be a lot of messing about, but I'm looking for something to investigate in my final year university design project and this might have some mileage, at least from a testing and analysis/ feasibility perspective.
Thoughts anyone?
It's either this or doing a translam enclosure with hollow walls and filling it with different materials to see what happens...
Any other suggestions for things to investigate in terms of enclosure shapes... or pretty much anything feel free to make em.
Has anyone investigated this much, with regard speaker enclosures? Had a search already and though people thought it wouldn't work (due to water allowing waves to travel within it easily) I know it's hardly the most practical of things to work with, especially with lots of electricity flowing round.
Anyway got me thinking about using something like those fillable ice cube bags (obviously not frozen and eventually designed specifically to be more durable) as sound deadening on the internal walls of a cabinet. Basically a cellular material with water (or maybe a gel?)in the cells. Imagine big bubble wrap but filled with water instead. I agree that a layer of water sandwiched between two walls would allow the rapid and efficient transmission of waves between the sandwich materials. However I have a feeling that by housing the water in flexible cells which are not physically fixed to the walls (maybe, say, hung from the top) the waves may be dissipated without being transmitted to the cabinet walls. Kind of like a hydro suspension kinda thing... imagine punching a water bed (bad analogy but the best I can come up with).
I know it will be a lot of messing about, but I'm looking for something to investigate in my final year university design project and this might have some mileage, at least from a testing and analysis/ feasibility perspective.
Thoughts anyone?
It's either this or doing a translam enclosure with hollow walls and filling it with different materials to see what happens...
Any other suggestions for things to investigate in terms of enclosure shapes... or pretty much anything feel free to make em.
Since water does freely transmit waves (altough it would be less compliant in small "cells"), it probably wouldn't be a good dampenning medium. Think of it this way- sound passes through the inner wood wall and looses X amount of energy, then passes through the air and water or cellular configuration almost unimpeaded, the the outside wood wall losing X amount of energy again. Cancel the water between the two panels and fix (laminate) them together; the sound energy lost will not just be 2*X, it will be somewhat higher.
I have yet to experiment with laminating wood and asphalt but I intend to in the near future. Some hobbiests are very pleased with the energy control. Look into replacing the water in your hypothesis with sand- car manufacturers have employed it in luxury cars to keep road noise down.
I have yet to experiment with laminating wood and asphalt but I intend to in the near future. Some hobbiests are very pleased with the energy control. Look into replacing the water in your hypothesis with sand- car manufacturers have employed it in luxury cars to keep road noise down.
Thanks guys, my thought was that water responds differently to air waves contacting it directly and via a medium such as the first layer of wood you talk about. (I wouldn't sandwich the cells they would be loosely attached inside a single walled cabinet). Bear with me through another analogy here... If you lay in the bath with your head submerged and someone outside the bath is talking the sound is very very muffled, in fact i suspect that most of the sound will come from the bath itself resonating due to the waves contacting it... thus being the medium through which sound waves are passed to the bathwater. If someone taps on the side of the bath it's really loud because the shock waves are dissipated directly into the water. My thinking is that this is because when hitting the soft surface of open water, the soundwaves are dissipated by displacing, or "wobbling" the surface of the water, albeit on a very small scale, and don't have the solid surface of transmission to transmit directly through the water.
the cells would have to be low pressure so there was slack to allow them to wobble/absorb/damp the waves...
Ummmm.... It's one of those funny ones where you know what you think but can't quite put it into words...
Does anyone think they get what I mean?
Basically I understand that the water itself can transmit sound, it's more how it relates to the surfaces and waves it contacts when not directly sandwiched between what I might as well call "mediums of transmission" for want of a better expression. I think how the mediums contact each other (strongly vs loosely) may make a big difference.
anyway... ho humm.
SAme idea could possibly allow for a more effective method of using bitumen or whatever substance takes your fancy.
the cells would have to be low pressure so there was slack to allow them to wobble/absorb/damp the waves...
Ummmm.... It's one of those funny ones where you know what you think but can't quite put it into words...
Does anyone think they get what I mean?
Basically I understand that the water itself can transmit sound, it's more how it relates to the surfaces and waves it contacts when not directly sandwiched between what I might as well call "mediums of transmission" for want of a better expression. I think how the mediums contact each other (strongly vs loosely) may make a big difference.
anyway... ho humm.
SAme idea could possibly allow for a more effective method of using bitumen or whatever substance takes your fancy.
I see what you're thinking and you're certainly not the first to think along those lines. I abandoned my thoughts about when I realized that water transmits too well and the only damping it does seems to be in the uppermost frequencies. Other than that it appears to transmit the other frequencies faster and with lower losses than air, rendering it less than useful for this purpose even with other components added to the scheme. I think the water in between panels such as in constrained layer damping is a worse option than just air in the gap.
Look at how the water is moved in a tsunami versus how a wind blows, that should help.
Look at how the water is moved in a tsunami versus how a wind blows, that should help.
There are quite a few knowledgable people visit here. One of the questions I saw asked which got a lot of feedback was about cabinets made of synthetic material such as epoxy-carbon and less exotic substances like concrete.
There is already a body of work documenting the performance of many materials, but nobody could say anything definite about some of the combinations suggested.
If you can't think of an exotic of your own that you favour, you could do the rest of us a service and build a test rig and test a few off-the-shelf or custom materials. Who knows, you might find something really good by accident if you had the convenience of an easy test.
I think something like a hole in the ground with a speaker in it and the test material as a trapdoor with a mic hung over it. You wouldn't get calibrated results, but you'd get good comparative ones.
w
There is already a body of work documenting the performance of many materials, but nobody could say anything definite about some of the combinations suggested.
If you can't think of an exotic of your own that you favour, you could do the rest of us a service and build a test rig and test a few off-the-shelf or custom materials. Who knows, you might find something really good by accident if you had the convenience of an easy test.
I think something like a hole in the ground with a speaker in it and the test material as a trapdoor with a mic hung over it. You wouldn't get calibrated results, but you'd get good comparative ones.
w
I haven't read any research on the use of liquids for damping/absorption so it looks like quite an open area for study.
I don't see water as a good medium due to it's high mobility. You want something that has a lot of friction to turn the vibration to heat. Hence sand and bitumen.
How about other liquids? oils? I like the gels idea.
honey?
playdough?
this could get really messy!
I don't see water as a good medium due to it's high mobility. You want something that has a lot of friction to turn the vibration to heat. Hence sand and bitumen.
How about other liquids? oils? I like the gels idea.
honey?
playdough?
this could get really messy!
Thanks for your responses everyone. I don't need convincing about how water transmits waves more efficiently than air (due to the free moving molecules but higher density) I understand this.
I don't think I'm managing to convert what I'm thinking into text as clearly as I like. But anyway, I dare say your points about water not being the best material to use are right. Maybe the best thing to do would be a comparative study of different substances which could be used in a translam design?
My next step would be to familiarise myself with the equipment required to record and measure the differences I suppose. What would be the best (free) software to use for recording/analysing/testing?
I could create a couple of (nearly) identical MDF sandwiches filled with different substances but to the same thicknesses. I would then run a frequency sweep through them (using some kind of enclosure) and record the levels.
Hopefully this would yield data on how well the sound was deadened, and which frequencies were most effectively dealt with by given material.
How might I test how well standing waves were dealt with? Any thoughts, or is that another ball game entirely
Thanks again, I feel this will be the beginning of many happy little conundrums shared amongst what seems to be a very friendly and helpful group of people.
Doug
I don't think I'm managing to convert what I'm thinking into text as clearly as I like. But anyway, I dare say your points about water not being the best material to use are right. Maybe the best thing to do would be a comparative study of different substances which could be used in a translam design?
My next step would be to familiarise myself with the equipment required to record and measure the differences I suppose. What would be the best (free) software to use for recording/analysing/testing?
I could create a couple of (nearly) identical MDF sandwiches filled with different substances but to the same thicknesses. I would then run a frequency sweep through them (using some kind of enclosure) and record the levels.
Hopefully this would yield data on how well the sound was deadened, and which frequencies were most effectively dealt with by given material.
How might I test how well standing waves were dealt with? Any thoughts, or is that another ball game entirely
Thanks again, I feel this will be the beginning of many happy little conundrums shared amongst what seems to be a very friendly and helpful group of people.
Doug
dnsey, I take it that the material in which the liquid is housed would then be important... I thought of using small very pliable (plastic) cells- like said ice cube bags- with this in mind. It should be flexible enough to allow the waves "into" the liquid, but hopefully the waves will just then bounce around inside, or at least be heavily damped.
I seem to remember seeing a patent (to Sony, I think it was) in which they used vinyl as a CLD layer between wood or MDF. I remember thinking that the kind of soft vinyl used for shower curtains or temporary green houses is what would be required. It's sort of "jiggly."
I once put up a temporary greenhouse in my listening room and it surely absorbed sound.
If this were to work the glue would have to cure really hard, I think.
What you need is materials with different densities and different speeds of sound. I suspect speed of sound in vinyl is slow compared to wood.
I can't understand how they got the patent but that's neither here nor there.
I once put up a temporary greenhouse in my listening room and it surely absorbed sound.
If this were to work the glue would have to cure really hard, I think.
What you need is materials with different densities and different speeds of sound. I suspect speed of sound in vinyl is slow compared to wood.
I can't understand how they got the patent but that's neither here nor there.
SY said:
I'm with Sy on this one.
Back in the last century I remember reading that the reason to use layers of different materials is because sound has to change speed in each different layer. Changing speed takes energy. The more changes in speed (and the greater) the more energy loss.
Maybe that 's some of what's going on in sand.
Air-sand-air-sand-air-sand-etc.
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