Anechoic Chamber - DIY Sound Absorption Panels 

"The neighbors really like this"

Thank God, a Tech Ingredients video. RU-vid has been suffering.

For anyone considering a DIY, If youre doing room size acoustic treatment treatment using foam, for the love of god, make sure its UL 94V-0, 94V-1, or 94V-2 rated (lower is better) for flammability. To prevent some sort of small ignition point spreading from floor to ceiling, wall to wall in a minute or two. If youre just doing a panel, its not as critical, but still wouldn't hurt to use something less flammable.

"I borrowed one of my son's antennae masts" We've all had that awkward talk!

"Audiophiles" take note. Often room treatments are more valuable than new speakers, amps, wires, sources.

I won't be satisfied until the entire room is filled with helium.

You are such a clever man, I would love to know where you trained and worked to gain such a vast array of knowledge. Also I want to say your method of teaching is absolutely brilliant! You are clear, concise and above all interesting. You keep me focused and engaged throughout. Thank you for sharing.

127 audiophiles dislikes couldn't afford acoustics after spending £20.000 on 1 meter speaker cable.

To make up for a double layer of insulation board, you can make some distance between the wall and the panel. E.g. if you use a 3" board, you can simply put in 3" spacers, and you almost get the same low end performance as if it was 6" thick. :) So the air between will help you save money (but take up more of the room) Just a tip. -- Thank you for these videos, they are GREAT !

I think your chamber will be very effective at higher frequencies but will not be anechoic in the bass frequencies. Professional chambers can have absorption that is a couple meters deep because low frequencies are so physically large. You can greatly improve the performance of your panels simply by spacing them off the wall. Doubling the distance from the front surface of the panel to the wall will move the effective absorption down an octave.

"The neighbors really like this." Thug life!

I'd be curious to see the frequency response curves for acoustic foam on the hard surfaces, drywall/plywood.

That lady, screaming and spinning round. That's me when I hear a recorder.

Have you done a Reddit AMA (Ask Me Anything)? I think your subscribers would love to know a little more about your operation. It's also free publicity :) You always amaze me with how extremely well rounded (yet humble) you are, and you deserve many more subscribers. Keep up the amazing videos!

There are easier and more effective ways of going about this. First, the materials you are using are only effective for high frequency sounds, High frequencies are generally fairly easy to deal with, Low frequencies must be handled in a different manner, and, inside a closed box, (anything that's indoors), Low frequencies are usually a bigger problem. Low and high frequencies can be handled at the same time, using much different techniques. "Special" sound deadening materials will always be way over-priced, and generally, don't handle the Low frequencies at all. "Rock-Wool" wall insulation is dirt cheap and comes in larger, more effective sizes. All you have to do is build a One by Four (by 3/4) frame to fit around the bats. If you want it to look nice, go to a fabric store and ask around for someone who can make you some custom covers. Next, and the most effective, is to buy Fiber Glass in bulk rolls. The rolls will be completely wrapped in plastic, DO NOT REMOVE THE PLASTIC, leave it in a roll, put them in "Lawn and Leaf" bags for extra protection, or you can have covers made just like with the Rock-Wool. Now here's the most important point..... The rolls MUST be placed in the CORNERS of the room. You can make a stack from floor to ceiling if you want. More is better, but you will immediately notice the difference with just ONE roll in one corner. They can be placed only in the corners near the ceiling, and be just as effective. Any location other than the corners will NOT be as effective, the corners of the room act like a horn, and all sounds get concentrated in the corners, so this is where you want to place your Low frequency absorption materials. After you get the Low frequencies handled, you may not find it necessary to do much on the walls. Carpeting, hung about 3" out from the walls, will absolutely slam any high frequency problems, the carpet doesn't necessarily have to cover the entire wall, unless you are actually trying to build a recording studio or dedicated listening room or Home Theater room. Of course, the heavier the carpet is, the better it absorbs sound. It can be fairly heavy, so you will have to get creative when hanging it from the ceiling. You can also wrap the Fiber Glass rolls, or Rock-Wool bats, with carpet to make them tougher. . .

"The neighbors really like this" lol that's the first thing i thought. I really enjoy these audio related videos. Audio is my favorite hobby.

Good vid :) I used the rigid insulation and foam way due to it making sense (and I had decent foam already which was going to be cheaper than buying cloth etc). But I used a wooden frame as it adds diffusion. Also with an air gap behind the panels the remaining/escaping sound reflects off the wall and has to go through the panel all over again. Really effective. Bass traps are all rigid but upto 6".

"After retiring from comedy, Bill Hader turns his genius to DIY science."

24:15 "And remember we're not building an airplane here, we're just sealing fibers" ...for some reason I'm laughing more than I should.

"the neighbors really like this". he's the absolute apex of deadpan dad jokes. my kind of guy!! This video is awesoome.

Hello my dear friend, you have come to talk to us again about the sound of silence

please do a video on your story.... what you studied and what you did before youtube!!!

We're all waiting to find out what the plan was with the magnetohydrodynamics, and he gives us... a recorder

Love the screaming!!!

Always such concise explanations, and just the perfect amount of background to give proper context. Keep up the good work!

That was pretty good and well demonstrated. Even better absorption can be achieved if the surface has longer and sharper spikes - this ensures that primary and higher order reflections have almost no chance of ever coming back out, so they are completely absorbed. Actually, an almost perfect anechoic chamber is a really uncomfortable place to be in!

The dislikes are the expensive panel companies that got wind of this. 🤣 I have a room to treat and it was going to run well into the hundreds of dollars, minimum. I'm not a professional and cannot justify that. But for a fraction of the cost, I can get results that meet my needs. Love the extra mile you give in explaining and showing the data. Cheers!

Why did you choose epoxy to seal the surface rather something less expensive? Seems like a lot of different things could be used that would serve the same purpose such as wood glue, latex paint or pretty much anything that will soak in a little bit and then dry to bind the fibers.

If you want to annoy your neighbors less by playing loud sounds you could also opt for playing it at a lower magnitude, but for a longer duration. You should still be able to obtain good signal to noise ratio from your measurements if you use Welch's method (a quick search showed that welch() and csd() in Python would do the same). By looking at the coherence you can also get an estimate of how good your measurement's signal to noise ratio is (so whether the spectrum is due to the generated audio or due to sounds from the surrounding).

Thanks! I really appreciate and enjoy your videos. I was only slightly disappointed when after all that testing, painstakingly measuring the performance of various materials, then you seemed to identify a solution to proceed with, you then modified that solution with the painted epoxy and wood insert, and then didn't go back and capture that modified solution's performance. My hunch is that if it changed, it changed very little, but it just seemed to upset the process you had established. Thanks again for your dedication and great videos

Thanks for this video! I've been watching and reading various soundproofing tutorials, with varying levels of concern expressed about breathing in the dust of the rockwool, and especially fiberglass. I think I like your method best amongst the options which include covering the whole insulation in plastic (which apparently is reflective), or just covering the insulation with a fabric that is required to be "very breathable" to let the sound through, yet somehow is expected to magically hold microscopic fiberglass dust in. The fact that they use the word "breathable" to describe the fabric that's supposed to contain the dust you don't want to breathe, is kinda funny. Do you think the epoxy would work right on the Rockwool Safe n Sound product? It's supposed to be soft and even somewhat crumbly, therefore annoying to work with... but acoustically capable, and available from my Lowes without a special order. I don't have experience with that material or epoxy, so I can't intuit whether the epoxy would set on it right. Also wondering if the epoxy would stabilize rigid fiberglass just as well. I'm trying to bring together every different tutorial I watched and whatever material I can cheaply attain and make something that I'm happy with. I'm also trying to figure out how I can cheaply, easily (and safely) make an imitation of the Realtraps Portable Vocal Booth.

​ @Tech Ingredients Love your videos! Just finished up my speakers from your previous videos: i.imgur.com/cTYb28E.jpg

Did you do the frequency response tests AFTER applying the epoxy? Couldn't there be reflections from the back now that it's more rigid?

I wonder well this would work for the hybrid jet engine?

Your videos are gold.

So, I have always held value in meeting very intelligent people. What is like for you to usually be the smartest person in the room? Who are some people that you hold in high regard because of their Intelligence? I feel like I would learn a ton hanging around you.

Your channel is incredible. Thank you for making such fantastic videos!

Just in case you are going to test more materials for panels: could you check how wooden sawdust of different granularity works? I know, the rockwool seem to be the optimal price/performance option, but still, you seem to be kind of person to test many options just of pure curiosity :)

it makes me so happy to finally see someone on youtube how uses protective gloves when working with epoxy. So many people think it's just normal glue and they can handle epoxy like so. Oh boy are they wrong!

Weirdly enough the recording of your voice inside the anechoic chamber seems worse than outside of it. I was not expecting that.

I oh so wish you had of been my physics teacher when I was in college . I'm sure I would have got better grades!

Somewhere in the woods there's a group of hippies tripping balls, and they to figure out where the alien ship landed.

If you wanted to dampen some resonant frequency’s in the large room with ceramic tile, could you build several of these putting decorative fabric on the outside so they would look like pieces of art hanging on the wall and help reduce the reflections of sound with in that room?

Good news: You're at home, so technically OSHA rules don't apply. Bad news: OSHA rules are written in blood. 3M has PPE recommendations in the SDS for Super 77 for a reason, and those include respiratory precautions and gloves. There are a very small handful of companies that write detailed application instructions for their products which actually work, and 3M is one of them. Don't ignore anything they tell you. Also, if you're not 100% satisfied with the way the Super 77 holds the foam to the rock wool, try FoamFast 74. It is specifically formulated for open-cell foam and "bonding acoustic foam" is explicitly mention in the specs. RTFM, people.

Why didn't have the speaker directed upwards and suspend the materials above it? You wouldn't have reflections from the trees that way.

Now I just need to figure out how to make portable versions of this so I can hammer out some bodywork in my driveway without having the neighbors call the cops.

Thanks for the video! In addition to sound absorption, do you plan to follow up with a video on sound diffusion as well? It would be educational to cover the respective applications of both methods.

You did not measure the acoustic foam or the self cut foam just by itself....

Wow! Your channel is very interresting. Thank you! You are very serious about the information you provide. "The neighbors really like this". Deadpan joke, that was awesome.

Greetings, I have made 4 2' x 4' panels consisting of a 2" deep wooden frame (wood about 1/2" thick), with approx 25 used towels of various weave and thickness, hung within the frame. I covered the front with a thin cloth for appearance sake and placed them strategically on the walls of my small studio. The effect was of eliminating, IMHO, 90% of the echo. Multiple blankets close off the area, hung over a chain reaching from one wall to the opposite. These blankets are of different thicknesses, fabrics and weaves. I am just amazed at what this has done to the reverb of my room. I also filled cloth closet hangers (the kind with cloth shelves) with as many towels as could be squeezed into each level. These were placed into the corners of my room. Through simple measurements I can see how much the bass has been reduced. My question,...or suggestion, is to how you might assess this type of approach. I am quite pleased, but the rest of the world is skeptical. Could you do some tests in this vein?

21:37 RIP my ears. Would be a good idea in future to dull the sound of your power tools in editing (especially as this is a video about sound dampening 😂😂😂).

time stamp this to 1:18 with no context and share to any contacts you dont value.

1:18 such a mood

I'm usually a DIY kinda guy, but... this makes me want to go out and buy my panels. That is a LOT of work for each panel. But absolutely amazing research, amazing instructions, and amazing work. Well done!

I was legit expecting him to play My Heart Will Go On like that meme LMAO 😂 the Internet has ruined me

Your gonna pull Sasquatch Sr. out of those woods. He's gonna say "what the he#$ is going on here da'!=t.

1:30 can we talk about his huge lung capacity

DIY Water Glass (Sodium Silicate) Cheap to make, great sealer and strengthener. Also, you might consider DIY French Cleats for mounting. Easy and Invisible. PS. You missed a spot.

*This is also good for keeping the noise/screams down so your family can't hear your other secret family you keep locked in the basement. Some people have done this for years and never got caught, another great use for 3M products* !

I saw a comment on another video saying to mount sound absorption panels about 1" away from the wall for even more sound absorption. Not sure how valid that is, but I'd like to find out if it adds to the effect.

What happened to that magnetic yoke you've been working on!?

You can just use cheap rock wool sheets from a hydroponics store. It is exactly the same material. 24x48x2 sheets usually come in boxes of 6 and are usually less than $80. It is highly recommended that you reinforce the edges with a water based resin and cover them panels with fabric like fleece or speaker grill cloth.

Forget the back sealing epoxy and the glue, make a simple Wood frame and cover with textil, Now place the panel 3" from the wall, it will give you nearly twice the effect of your panel by slowing down the air and forcing it to pass different element. panel>air>bouncing the wall>air> panel again.

Width of testing panel sets lower limit on frequency absorption properties. This could be explained in the video, a graph of the frequency dependent absorption function of an ideal absorbing material would be useful before the outside demonstration. Am I right, if I say, your testing panel were 50cm sided squares? If so, wavelength long enough to be comparable to the width of the testing panel start to "skip" the panel. The maximum wavelength we can absorb reliably is dependent on the test panel width and the average distance from of sound traveling from the source to the receiver. This also explains the repeating peaks and lows in the absorption spectra you measured.

In my opinion, your test is not quite correct. You have on the one hand chosen material (dry wall, plywood and the rock wool) flat under a fixed angle to the mic, and then you showed a panel with angled foam stripes, which will also have a direct reflection away from the direction of the microphone . So the only way to measure correctly would be to measure the reflections over the front half of the whole space angle, at minimum 180 degrees in one level perpendicular to the pole centered to the device under test, if your triangular stripes are all vertical. I hope you understand what I mean, I am a German so sorry for my English.

Please, next time, turn down the volume of the extra loud events in post. The measuring tone was kind of painful to my ears (cheap TV speakers). Love your videos non the less! Also, I agree with the other comments that lower frequencies usually are the main issue in home listening situations. Yet the topic of the video is that but an anechoic chamber. 😉

What are you doing?! Wedges for anechoic chambers are measured in an impedance tube. The result is the absorption coefficient over frequency for 0 angle incident of a plane wave with sound hard backing. Look up ISO 10534, part 1 can be done with rather simple DIY methods. Roughly speaking the wedge must have a length corresponding to 1/4 of the wavelength of the lowest frequency to absorb where the absorption coefficient shall be >0.99. A low cost wedge material that is commonly used is glass wool with low flow resistivity. Inside the treated room (6 absorbing surfaces for loudspeaker measurements, so wedges also on the floor) within the volume one wedge length away from the tip of the wedges the sound pressure drops proportional to 1/r. The qualification is done with a dodecahedron loudspeaker and sliding microphone, not with a recorder and an office chair. You must not use the absorption coefficient from datasheets for room acoustic treatment sheets to design an anechoic room. The absorption coefficient is measured in a diffuse field in a reverberation chamber and gives values for random incident. What you are looking for in an anechoic room is full absorption of the FIRST wave hitting the wedges. Instead of doing all that chumbawumba trying to build a horrible anechoic room and waste money you might as well just have measured the speaker outside on the pole and gate the measurement....

For large walls you can actually find the nodes as mentioned with the mirror technique, place one panel at the node, then use alternating panels and equal width spaces, as long as the panels are thick, it forms a diffraction grating for the mid frequencies. In many cases you only need to cover about 21 feet of each wall, which when you do the math, is a half wave for bass. After calculating the wavelengths, this saved my place of worship a fortune in panels. Helps if you slightly tilt the panel from the top, thus an air gap forms which decouples the panel from the wall. This gets you another 2 dB.

I love how it's perfectly rational to you to just decide to build an anechoic chamber because you had tested speakers with suboptimal results. You all are an inspiration and I'm glad I found your channel.

Just a question: would it be okay to use spray adhesive and cheap cloth to seal in the fibers and only use epoxy to hold in the wood? Epoxy is insanely expensive for a quality brand here in Canada.

1:20 now thats some quality meme material right there

"You were right, we were wrong. So we built an anechoic chamber . . . no big deal or anything." - Absolute Mad Lad, 2018.

Now I have to make panels to test adding butyl rubber strips to see if I can capitalize on the reflections while dampening the peaks they cause. I see how you managed to fill a 5,000 sq ft lab... Also, preventing all reflections sounds terrible (it sounds dead). A mix of absorption and diffusion is important. Full bookshelves make a nearly perfect diffusion surface.

Nobody: Tech Ingredients: 1:14

What is the kind and density of the foam that you cutted (the green one and last in the sound absorbtion comparison? Great video though with huge value!

Could you link the material?

I surprised that changing the properties of the surface of the panel with the apoxy does not change the acoustic performance of the panel.

Frankly, the routing part was the less convincing technique. Loud, dusty, potentially harmful. Better way would be to cut the 4 outer lines of the wood panel, use a less thick but still structurally suitable wooden panel and press this down while having applied your epoxy or another type of glue. Compressing the fibers might even give a further advantage. Thank you for your shared knowledge. Your family workforce is admirable.

Free improvement: add an equivalent thickness air gap between the panel and the wall to more effectively capture low frequencies while not sacrificing high frequency absorption

That one eyelash you put in the middle of your face. Awesome. Given how smart you are, I think you may have done this on purpose. Great vid. More please.

I normally fill my listening room with helium and then blast air from the speaker to my head to listen to it.

How would you feel about putting rockwool safe n sound on top of the comfortboard? More frequency spectrum absorbtion

GREAT VIDEO

Your videos are packed with great information. I thank you for your time and teaching abilities. You could hear the difference of the test signal as soon as you put the panel up. Thanks for yet another cool video!

I think you said you were using ROXUL 80? If you used ROXUL 60, you'd get much better absorption in the high freqs than the 80. The 80 is actually fairly reflective for higher freqs compared to the 60.

What are the products you are using? Might have missed where you mentioned it, but, I can't find the particular Roxul and the cut-it-yourself foam you used. Thanks!

I think you may trigger a meme: _"Man with very intensely concentrated face, spins around slowly on office chair in anechoic chamber, playing recorder"_

Omg I have to make a dubstep song with that quote.

I love you man! I wish you were my neighbor!

Interesting as always! I second the request that it would have been nice to see (hear?) results from just the foam over plywood. Also second the comment on fire/flame: could we get a statement as to whether the specific materials you have used have fire resistance? Also to second the comments on sound measurements, with a little more explanation for those not familiar: A way to get your measurement to represent just the speaker output, or to get reflection measurement to show just the first reflection, is to process the sound received at the microphone to ignore the room or house reflections. This can be done because the room reflections arrive after the direct sound due to the longer path. Classically this was done on an oscilloscope that allows a time gate, the gate closes after a certain point in time after the sound begins, and no longer measures after the first arrival time has passed. It appears that the REW software includes this functionality (haven't used it myself). I understand that what you thought would work best for illustration purposes is a frequency sweep, but you'd avoid having to do the whole outdoors thing. You have to burp the sound at a series of discrete frequencies then graph it out. The same method is obviously useful for the later re-test of the speaker panels, as it takes the environment out of the response function.

you guys are truly amazing.. I'm speechless.. so, kudos!

More audio! Thabks for you're efforts! I would love to see a website or wiki with your data and papers for the community! Shoot, I'd even pay for it.

It's so easy and kind to listen to you, so informative, so happy the found this. I will try it, thank you. Such a good teacher

*Can you do a video on RF or that amp your son made in a video a while back (the one where the sound died* ). You must get great propagation and RF quiet reception being located in rural Maine (it looks like Maine). Or vids on antennas. There are A LOT of hams that watch youtube and would love to see your create approach to building antennas or stuff on HF or SW.

have you measured the cricket distortion?

Is he saying “roxul”, or “rock wool”. I want to try this but not sure what product he’s using.

Please please please......DIY 18650 powerwall step by step fulll Guide for Dummies....

0:27 Please remove the LOUD ANNOYING music when you are talking

This video inspired me to soundproof a couple hallways (without blocking airflow) using rockwool and it has worked quite well. After thinking long and hard, I decided to go with rockwool + polyester body pillow cover! Some of them are just the right size. I think the dense and fluffy ones will do a sufficient job of containing the fiber. I did not want to use the spray adhesive because rockwool+polyester is quite fire resistant and I didnt want to mess up the math by introducing the spray. Also, if the spray is applied too heavily, it'd create a tough shell that would bounce the sound waves. This way I am more confident that my absorbers are working properly (since I cant really test it like this video). Once the rockwool is in the cover, I staple the fabric to a panel/drywall/etc, the fabric is enough to hold the rockwool against the wall. I really feel like this is the ultimate soundproofing solution when it doesnt need to look good. They do not look neat but the cost and time savings are out of this world! 6 bucks for 16x48x3 rockwool safe'n'sound. 9 bucks for the particular 21"x54" Body Pillow Cover I bought. Having pillows stapled to your wall: priceless. Also it basically takes 2 minutes to put the rockwool in and you're literally done. Also, I would be interested to see how densely woven polyester compares to these. However, one needs to be careful with those, amazon has a bunch of listings for identical looking items that weigh drastically differently. I bought a 12 pack of 12x12x0.4 for $18 and $30, the $30 was twice as heavy. It is clear these cannot compete with the price performance of rockwool, but they are ready to use and look fine.

brilliant stuff! and thank you sir, you have a wonderful afternoon too xx