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Memory Foam Vs. Conventional Foam vs. Acoustic Foam
Old 6th December 2012
  #1
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Memory Foam Vs. Conventional Foam vs. Acoustic Foam

New University of Washington study, Aeronautics and Astronautics Dept, presented in Berlin...some interesting findings (PDF):

https://encrypted.google.com/url?sa=...32HhKw&cad=rja

...of note:

1) Memory foam has more linear sound absorption across spectrum
2) Memory foam is nearly as absorptive as sampled acoustic foam
3) Directional absorptive qualities of MF comparitively

...seems like it might be a good candidate for first reflection surfaces...like back of room directly across from monitors or as all purpose cloud or wall where $$$ adds up quick.

4"+ visco memory foam is pretty cheap these days...comes covered in fabric and would be easy to stuff in DIY frames.

Any thoughts appreciated. Before people start blasting me, read the study...it discusses three angles of incidence, shows reduction graphs across the freq spectrum, etc. SCIENTIFIC.

I've been researching for treating my ceilings with clouds.
Old 6th December 2012
  #2
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Quote:
Originally Posted by slackstallion View Post
New University of Washington study, Aeronautics and Astronautics Dept, presented in Berlin...some interesting findings (PDF):

https://encrypted.google.com/url?sa=...32HhKw&cad=rja

...of note:

1) Memory foam has more linear sound absorption across spectrum
2) Memory foam is nearly as absorptive as sampled acoustic foam
3) Directional absorptive qualities of MF comparitively

...seems like it might be a good candidate for first reflection surfaces...like back of room directly across from monitors or as all purpose cloud or wall where $$$ adds up quick.

4"+ visco memory foam is pretty cheap these days...comes covered in fabric and would be easy to stuff in DIY frames.

Any thoughts appreciated. Before people start blasting me, read the study...it discusses three angles of incidence, shows reduction graphs across the freq spectrum, etc. SCIENTIFIC.

I've been researching for treating my ceilings with clouds.
The paper focuses on insertion loss, not absorption.

Andre
Old 6th December 2012
  #3
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Quote:
Originally Posted by avare View Post
The paper focuses on insertion loss, not absorption.

Andre
+1 big time.......

Rod
Old 6th December 2012
  #4
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Avare and fanboy Rod I know you are the self declared treatment gurus with financial (and egotistical) stakes on this forum.

I feel honored that you two were so quick to chime in with scientific wisdom and nuance attempting to discredit a simple inquiry into memory foam. It really does say a lot to people reading this thread. I think you guys are too busy palming the other parts of your bodies. Clearly after 6000 posts between you two, you've found better ways to answer a reasonable OT inquiry?

re: not absorption...Where do you think those extra decibels go at an angle of incidence of 80 degrees? That they scatter coincidentally at almost the exact amount that the other two absorb? Come on!
Old 6th December 2012
  #5
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Did you bother to read the PDF and determine what the test was intended for? If so please explain exactly how that translates into a room treatment analysis? I'm always willing to learn - teach me........

Next time I want to build a wind tunnel I will probably consider it........

Better yet - just buy and use it for your room........

Rod

PS?: just for the record - insertion loss is specifically noise reduction in decibels provided by a silencer or other similar device when inserted into a duct or other noise path under static (no flow) conditions; when flow is present it is referred to as dynamic insertion loss (DIL). we study IL & DIL extensively for the purpose of HVAC analysis for duct borne transmissions.
Old 6th December 2012
  #6
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No problem Rod, give me a day to formulate an articulate response with citations and post it here for all to read for the record. I see you quickly shifting the focus of this "discussion" to something you are more comfortable ranting over, i.e. room treatment analysis. You're only discrediting your reputatoin in the whole matter with your initial self righteousness, but I will be happy to post it for all others to maybe learn (and maybe I learn quite a bit,too).

P.S. a quick insertion loss definition doesnt show any real integrity.

In the meantime, please tell us where all that extra energy goes at 80 degree AOI.
Old 6th December 2012
  #7
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lol............
Old 6th December 2012
  #8
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I'm laughing at you too Rod. You trapped yourself in a corner on this one. No pun intended.

Old 6th December 2012
  #9
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LMAO _ I just want to see how you translate this test sample for liner in a wind tunnel into an equivalent test in a reverberation chamber.......

That will be a good feat.

BTW - just for the record here - seeing as you mentioned scientific and all that - I find it very interesting that you are able to draw conclusions that the people performing the test could not........ their conclusion was that this merited further testing....... you apparently should have been involved in the report - I'm sure then it would have drawn more concrete conclusions.

OH - missed this initially - you said:

Quote:
I see you quickly shifting the focus of this "discussion" to something you are more comfortable ranting over, i.e. room treatment analysis.
However it was not I who did this in this regard - it was you in your first post (which I will quote in it's entirety just in case you decide to edit it after the fact, I will bold and underline the pertinent info for the sake of clarity):

Quote:
Originally Posted by slackstallion View Post
New University of Washington study, Aeronautics and Astronautics Dept, presented in Berlin...some interesting findings (PDF):

https://encrypted.google.com/url?sa=...32HhKw&cad=rja

...of note:

1) Memory foam has more linear sound absorption across spectrum
2) Memory foam is nearly as absorptive as sampled acoustic foam
3) Directional absorptive qualities of MF comparitively

...seems like it might be a good candidate for first reflection surfaces...like back of room directly across from monitors or as all purpose cloud or wall where $$$ adds up quick.

4"+ visco memory foam is pretty cheap these days...comes covered in fabric and would be easy to stuff in DIY frames.

Any thoughts appreciated. Before people start blasting me, read the study...it discusses three angles of incidence, shows reduction graphs across the freq spectrum, etc. SCIENTIFIC.

I've been researching for treating my ceilings with clouds.
As far as this comment goes:

Quote:
Avare and fanboy Rod I know you are the self declared treatment gurus with financial (and egotistical) stakes on this forum.
I guess you could say I'm a fan of Andre - met the man in person - and he's a great guy as well as being a very talented acoustician, but - I have no financial stake here - nor at any other web site..... as far as ego goes - heck - everyone has an ego (yours seems pretty inflated to boot here)

Rod
Old 6th December 2012
  #10
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slackstallin - Unfortunately, you have ruined your own credibility by turning this into a personal attack on Andre and Rod, and it comes off as just being a troll. Even if your OP had some useful information which could be discussed on a scientific level, the value of it is severly diminished by the attitude that followed.
Old 6th December 2012
  #11
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EricF,

please pile on, I could care less since you aren't adding anything to the discussion. I actually view your comment as trolling, trying to incite an emotional response and nothing else, just like the overused facepalm. Us not being acquainted shouldnt affect your interpretation of the research and what it might suggest that's up for discussion. As you can re-read in my initial post, I would LOVE to get some insight into the matter.

Anyway, can someone else please inform me: Where do those extra decibels go at an angle of incidence of 80 degrees?


Also for Rod, this is from Owens Corning website, just in case you decide or want to edit your own definition:

"Insertion loss, IL: Of a silencer or other sound-reducing element, in a specified frequency band, the decrease in sound power level, measured at the location of the receiver, when a sound insulator or a sound attenuator is inserted in the transmission path between the source and the receiver."


...I am gathering a bunch of info and will post back tomorrow (if I havent been banned by then for pissing off so many with my unreasonable behavior).
Old 6th December 2012
  #12
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Can you please tell me how you can infer more from this than the people who actually did the test?
Old 6th December 2012
  #13
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Quote:
Originally Posted by slackstallion View Post
EricF,

please pile on, I could care less since you aren't adding anything to the discussion. I actually view your comment as trolling, trying to incite an emotional response, just like the overused facepalm. Us not being acquainted shouldnt affect your interpretation of the research. As you can re-read in my initial post, I would LOVE to get some insight into the matter.
My point was that your attitude sucks and it's a distraction from a decent discussion.

As for the topic of memory foam...
Assuming that your conclusion of it being "nearly as good" as acoustic foam is accurate, I'm not sure I see a benefit over the industry standard absorptive materials for acoustics applications (OC703, rockwool, etc.), which are significantly better than the products marketed as acoustic foam.

Then again, I'm not nearly as educated on the topic as the people who have already dimissed the report as being useless for evaluating the acoustic properties in a studio setting, and I might be missing something.
Old 6th December 2012
  #14
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Quote:
Originally Posted by slackstallion View Post
Also for Rod, this is from Owens Corning website, just in case you decide or want to edit your own definition:

"Insertion loss, IL: Of a silencer or other sound-reducing element, in a specified frequency band, the decrease in sound power level, measured at the location of the receiver, when a sound insulator or a sound attenuator is inserted in the transmission path between the source and the receiver."
I don't want (or need) to edit anything - the report you linked to is speaking specifically about wind tunnel tests....... the definition I used is 110% accurate.

Rod
Old 6th December 2012
  #15
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Eric,

Fair enough, except I never said "nearly as good"...nor did I conclude that. I said, "nearly as absorptive", which isnt necessarily the same thing (comparative absorption is proven in the study)...What I actually said is that it might be a good candidate. I was careful with my words in the OT. You can't expect to put words in people's mouth and not get called out on it. But I would like to know what is your opinion on memory foam for treatment?

Anyway, that's why I posted the initial inquiry in the first place. I wanted opinions with some substance. I gotta get back to work, will post more tomorrow.

FYI, 4" memory foam can be had for less than $2/sq ft, already cleanly wrapped in fabric ready to drop into a frame. 2" OC 703 with edges is roughly the same price. Auralex 2" acoustic foam is about 5x as much.
Old 6th December 2012
  #16
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Quote:
Originally Posted by slackstallion View Post
Eric,

Fair enough, except I never said "nearly as good"...nor did I conclude that. I said, "nearly as absorptive", which isnt necessarily the same thing (but is proven in the study)...What I actually said is that it might be a good candidate. You can't expect to put words in people's mouth and not get called out on it.

Anyway, that's why I posted the initial inquiry in the first place. I wanted opinions. I gotta get back to work, will post more tomorrow.

Since you want to argue semantics...

Quote:
Originally Posted by slackstallion View Post
2) Memory foam is nearly as absorptive as sampled acoustic foam.
I apologize for using "nearly as good" instead of "nearly as absorptive" in reference to your post. For the sake of this discussion, I was buying in to your posted conclusion to make my point. The point is still the same.

I appreciate that you're looking for alternate materials that might be both effective and cost saving for acoustic treatment. Props to you for that.

Without testing that follows the standards used for all other acoustics materials to be able to compare the critical data for the application, all we can do is make guesses. Telling me the horespower of a vehicle's motor and asking me to conclude how fast the it will go isn't enough information to provide an edcated guess.

Quote:
Originally Posted by slackstallion View Post
FYI, 4" memory foam can be had for less than $2/sq ft, already cleanly wrapped in fabric ready to drop into a frame. 2" OC 703 with edges is roughly the same price. Auralex 2" acoustic foam is about 5x as much.
Per the local price quote I got yesterday for Thermafiber SAFB, 4" of the stuff would be about $.78/SF. Of course, this doesn't include the fabric, but fabric is pretty cheap. When you factor in labor, you might end up with a toss-up between a SAFB panel and your proposed memory foam panel. There are a couple of questions though...
- Is the fabric on the memory foam breathable enough to be acostically transparent?
- Can I get it in burgandy to match the rest of my panels?

This still doesn't approach the primary concern, however, about whether or not memory foam is effective as a broadband absorber.
Old 9th December 2012
  #17
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It could be that slackstallion is confused as to the usage of the word "silencer" in this application. not a knock at you stallion; as different parts of the world may refer to things with different terms.

In this case, "silencer" isn't referring to absorption in the same way as room acoustics are concerned. A silencer for a gun, wind-tunnel, a car muffler, or for an HVAC system -- uses different principals and goals than are needed in room treatment. Different situations entirely. Different physics are involved.

That said, i (and others) would need to see lab reports for the correct usage of said product to determine its practicality in an acoustical setting. The linked report above is not such a report.
Old 23rd May 2019
  #18
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So from my beginner understanding, a pressure waves hits the material (foam, mineral wool etc.) Particles are pushed around and loose energy through heat and friction in the panel material. This decreases the energy of the sound wave and therefore lessens reflections. If insertion loss is a ratio of untreated dB to treated dB, does it matter if we are talking pressure, or air velocity, or...anything? If memory foam in a wind tunnel, "absorbs" the energy of the air or pressure wave, which is made of air I'm pretty sure, isn't this the same mechanism that drives acoustic panels? Energy dissipation through heat? Particles move > material steals some of their energy > particles move less...aka sound absorption. What am I missing?
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