Anechoic Chamber - DIY Sound Absorption Panels

We have constructed an anechoic chamber for testing speaker performance. You will get to see some of the testing of the materials used and a demonstration of how they can be incorporated into low cost, stand-alone acoustic panels.
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[@CKOD]

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.

[@EgonSorensen]

Great video, and a great comment! My thoughts exactly. Fire and health hazard(s) isn't really touched upon. Please do a follow up video and set a panel on fire using a blow torch, lighter and perhaps just even using lit gaze (variants of UL lab testing). Does it extinguish right away, smoulder, drip, liquid up and run, etc. It would be super nice to know before making replicas and learning the bad/hot way inside your house that they easily burn (or at a customer/friend if done for profit/favours) now that you have made this great DIY 'reference' video. Another thing I noticed: PPE (Personal Protection Equipment) - such as gloves when handling the spray glue (it gets sprayed onto the hands), and ample ventilation/or correct type breathing mask when handling the epoxy (also flammable). I know it looks green, but does it contain volatile solvents and other irritants/toxins? @3:33 - Audio sweeps, and 'The neighbours really like this' - what really??? I hope you're not serious (it sounds so), but I am truly assuming you're kidding. I like your videos, great info - however replicating some of them is not without it's risk (Lasers, jet engines, and so on). Keep up the great work. Thanks! - and have a great weekend, evening and afternoon as well :-)

[@raykent3211]

Yeah, the core is probably mineral wool, not flammable, but the surface foam may be highly flammable and worse, produce very toxic fumes.

[@RobertSzasz]

Nice super insulating foam has yet another fire risk. A moderate flame can cause the entire surface of the room to ignite through radiative heating. Low density organic foams are scary building materials

[@jothain]

This is a very, very valid point. People should look up how flammable some of the foams are. Note some. This can indeed be done by foam, but people use correct type. Don't be the idiot I saw some time ago making insulation video for home owners. He was using flammable foam which he was pushing through holes of ie. light switches etc. conduits for electrical cables etc. Pretty much every where he could see a cold bridge with thermal camera. Might look professional to someone and now that building will lit like oiled torch after pretty much any small electric problem..

[@raykent3211]

@@jothain à moment's silence for the victims of the Grenfell tower block fire. The block had been retrofitted with external foam-core cladding which went up like a roman candle and was entirely out of control in minutes. Many died. It seems that a lower grade material than required was used. I don't know how much better the correct one would be. No idea either why they didn't use rockwool.

[@Lydboxendk]

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 !

[@TechIngredients]

That's true.

[@iFlyGood]

Saimlar way the blackfeet indians insulated their portable tee pees!

[@skuzlebut82]

Thank God, a Tech Ingredients video. KZbin has been suffering.

[@barabolak]

Subscribe to AvE and This old Tony

[@stcredzero]

Currently the most awesome hard science+practical tech channel on KZbin!

[@skuzlebut82]

@@barabolak I have been for a long time.

[@patrickwatkins7572]

brilliant work, i should raise my game with my off grid generator videos

[@JohnJones1987]

@@patrickwatkins7572 Do you silence you genset with anything?

[@mavos1211]

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.

[@laurabrown3007]

Acoustic Foams are used for Echo & Acoustic Curtains are used for Soundproofing SoundProof-Curtains.me

[@Lukegear]

"The neighbors really like this"

[@andersprivat697]

I had to replay that severely amusing statement, several times hahaha

[@909sickle]

I laughed. His dry articulate speaking style makes it even funnier.

[@TwoScoopsOfTubert]

This guy is too dry LOL

[@BrendanOrr]

Especially after the nighttime jet engine tests, eh? For science!

[@miklov]

Haha, that was said exactly as I thought "I wonder what their neighbors think since they got a bit salty with the jet engine".

[@Lazerecho]

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

[@turosfagyi]

he didn't simply borrow it, he downright commandeered it :)

[@evilgeniusfin]

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

[@kensmith5694]

Yes, two parallel walls can make for very weird effects in sound.

[@ThetaReactor]

Like "audiophiles" are gonna be interested in anything that's only $4/sqft. Next you're gonna tell me I can make great speaker runs with that spool of Romex the contractors left in the crawlspace...

[@Jl4zio]

@@ThetaReactorAs long as that Romex is oxygen free copper.

[@kensmith5694]

@@ThetaReactor The stranded stuff for pulling into conduit works great for doing speaker runs. For really long runs, 2 pairs of wire works better than a thicker pair because it is easier to run around curves

[@dreggory82]

@@Jl4zio Oxygen free copper is a marketing scam, as soon as you strip the wire it's no longer Oxygen free. But Audiophiles will pay for it and the placebo effect will make them think it sounds better.

[@ZandarKoad]

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!

[@creativesymon]

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".

[@KGReef]

"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.

[@laserfloyd]

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!

[@benjaminnielsen2872]

Or the neighbors 😂

[@GameGuideClassic]

This is actually really very good and informative. I know the video is old, but it gives a good indication about the absorption of certain products. From there, it's easy to work out how much you would need to start working on the low end frequencies. Most companies only post data down to 125hz. Your advise about gluing the roxul together is also correct and often time people wonder why it doesn't work right because they literally have it jammed together in a box.

[@stephenrobertson2197]

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.

[@TechIngredients]

The Roxul spec sheet shows that the absorption at 125 Hz and 7.5 cm thickness is 75% (21% @ 4cm). There is evidence that allowing the panel to flex under the pressure wave enhances sound dissipation within the material. In our chamber, we hold these panels away from the rigid backing walls with foam spacers. Because of space constraints, we were unable to achieve a spacing as great as you suggest, but it should help.

[@onemic-theminimalist]

@@TechIngredients There is a lot of music going on below 125 Hz. Killing the top and mid only will make a room sound muddy except for maybe your flute. Also testing outside where the sound is traveling through the material and never returning is not like a real room with rigid walls that produce standing waves and nulls in the audible range.

[@ryansjunktruck]

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.

[@willjosephson]

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.

[@theepicslayer7sss101]

this Video has Perfect ads placement! (it does not cut in the middle of a explanation and makes it non disruptive!) and this content can be very helpful! my room is surrounded by everyone... my dad and brother are one wall away and so is the neighbors! my brother works at night, my dad sleeps late and the neighbors sleep early and wakes early... that compress the usable hours in a day a ton!

[@sillydilly2725]

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

[@TechIngredients]

Thanks!

[@JabberGulch]

@@TechIngredients Do you think this would still be the best way to make diy soundproofing four years later? Love the videos 👍👍

[@mikeperry2561]

As an Audiophile that started back in the 70's, I appreciate your channel. Seems a lot of people can criticize and don't appreciate the time and effort that goes into your videos.

[@TechIngredients]

Thank you.

[@mikeperry2561]

You are most welcome, and thank you for doing what you do.

[@wardope]

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!

[@Lennard222]

What happens if you don't?

[@jhonviel7381]

@@Lennard222 covid

[@clayz1]

I find myself watching these vids full length. This particular video is all about my sound system at home. It’s all about everyone’s sound system, because all you need to do is like it to think it is awesome. If you have money to spend you can start by adding quality components, then when it doesn’t seem quite as right as it sounded on the radio in your car, you can start awesomizing the walls in your room. I am all about improving my sound space for my great components with their expensive connecting cables. It is awesome and clear indeed. But! The space is not right. Yet. Must buy foam...

[@gregfeneis609]

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

[@laurabrown3007]

Acoustic Foams are used for Echo & Acoustic Curtains are used for Soundproofing SoundProof-Curtains.me

[@ssbeats2212]

BEST TEST EVER !! I.VE BEEN WATCHING A LOT OF KZbin VIDEOS ..BUT THIS ONE IN THE WOODS WITH ALL THAT EQUIPMENT ! MY GUY BRAVOOOO..

[@bugleboy96]

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!

[@TechIngredients]

Thanks!

[@rohanwallis1659]

Yes I agree this is some of the best TV I have ever watched. So well constructed, factual and informative ... brilliant ..

[@laurabrown3007]

Acoustic Foams are used for Echo & Acoustic Curtains are used for Soundproofing SoundProof-Curtains.me

[@TheAhingge]

this channel is all about how to beat commercial or industrial product with over kill research and analysis. DIY in high doses of knowledge, because this guy is very smart.

[@evanparker]

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

[@Coneman3]

They've probably tried to section him lol

[@thedevilinthecircuit1414]

A really great way to attenuate low-frequency standing waves in a room is to hang an unbacked carpet about 2" from one wall. It acts as a sound trap and gets rid of the boominess and low-end mung. We used to do this in our band practice spaces and it worked really well.

[@kwinvdv]

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).

[@laurabrown3007]

Acoustic Foams are used for Echo & Acoustic Curtains are used for Soundproofing SoundProof-Curtains.me

[@greggcheap6208]

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!

[@ahaveland]

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!

[@TechIngredients]

You're right. We only showed the back half of the chamber. When it is closed up and you're in it, it's not so nice.

[@laurabrown3007]

Acoustic Foams are used for Echo & Acoustic Curtains are used for Soundproofing SoundProof-Curtains.me

[@DestroManiak]

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.

[@TechIngredients]

😀

[@alextotheroh8071]

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

[@aayushmaanlala]

The amount of work you've put in behind this is not something we get to see on any other channel Thankyou for not taking the click bait route Love and support

[@landonkryger]

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

[@johnalexander2349]

I'm building a generator silencing box, and the sandwich I'm planning is 32mm ply, 6mm GP45 rubber, and 30mm "Sondor Hush" acoustic foam. Now I'm wondering if there's a better way...

[@AshkanKiani]

If you assume the effects are linear/additive, then maybe you get get an estimation by subtracting the difference between the waves shown and adding it to the ones for drywall/plywood.

[@siggyincr7447]

That's what I was wondering myself. He went from the rock wool to covering the rock wool with the acoustic foam without showing the effects of the acoustic foam all by itself or mounted on a hard surface. It could very possibly be that acoustic foam glued right onto drywall would have nearly the same effect, though my intuition says that the free hanging rock wool/foam assembly will reduce low frequency sound better. All that being said, it's an interesting video that got me thinking about something I never really thought about. So if they are reading this, please don't take the criticism as anything but nit picking at an excellent video. Keep the videos coming.

[@AaronAlso]

The simple unscientific answer is, minimal. Most acoustic foam is just over priced mattress material. It will reduce the mid/high reflections but does virtually nothing to lower range frequencies.

[@777Looper]

Same.

[@willb3698]

A friend of mine built a studio - but he made it as a "Straw Bale Building" (google it if you are not sure). This means that there are NO parallel surfaces, and down at the 1 cm range, there are still none because the render was applied by a human hand - not a tool. With less Absorption and no need for diffusion it's the best room I have heard. He put some Focals in there and it gave me a stiffie. Brilliant acoustics, naturally in a very environmentally wise building. Which sits on old tires. Not even ground based noise.

[@jimbrown563]

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. . .

[@TechIngredients]

Thanks for the comment. Those are "sound" principles. However, we decided to use these materials for the construction of a dedicated room of very small dimensions. Therefore, the cost which might be unacceptable for a full listening room is less of an issue. The rock wool, in a 7.5cm thick layer, has a single pass absorption coefficient of .75 @ 125 Hz. The panels are held away from the rigid (reflective) structure of the chamber's walls and so the sound will make a second pass before reentering the enclosure.

[@jimbrown563]

@@TechIngredients " a single pass absorption coefficient of .75 @ 125 Hz. " This "sounds" impressive on paper, but remember, decibels, and your ears, operate on a logarithmic scale, and, below 125hz is precisely the frequency where things start to get difficult to control. A 125hz sound wave is around ~8 feet long.... How big is that panel ?? How big is the wall that it's on ?? How far away is the nearest opposing parallel wall ?? How high is the ceiling ?? An advertising claim like that is highly questionable, and likely just a bunch of hot air. The highest average sound pressure levels are in the 8 corners of the room, and it's all unwanted noise. ( Placing speakers in the corners at the ceiling works very well BTW ) Direct reflections from walls, while they can be an issue, are not as important as the fact that the floor and ceiling, and all 4 walls, are precisely parallel to each other, and usually of similar dimensions, ( very close to a cube, the absolute worst case for setting up a massive low frequency resonant peak, or several that are fairly close to each other ). Your ears do an astounding job of filtering out reflected sounds, especially sounds that have a wavelength that matches the distance from your ears to the floor, and when ALL reflections are close to eliminated, it can be a startling experience, because you get a certain level of spacial stability and relative location in the space you are in that is constantly, and automatically, calculated by your mind, based on reflected sound. Most people have no idea of how much reflected noise they tolerate, or ignore, everyday. One of the best ways to identify problem resonances is to use a single omni-directional microphone (like in a LapTop or a Cell Phone) and listen to a recording made of your speakers in the room in question. Listen to the recording with a high quality set of headphones. You won't believe how BAD it sounds, and it's not the microphone's fault, it's room resonances and reflections, without the compensation or cancellation that you ears automatically provide. . .

[@raykent3211]

Yeah, I enjoyed the video, but there aren't many people who actually want to build an anechoic chamber. To pick up on one of your points, if you do want to build an anechoic chamber, then start by having no parallel surfaces. I once rehoused some speaker drivers from rectangular boxes into rhomboidal (?) boxes on that principal (no sides parallel). They sounded better, or maybe I was kidding myself. Theoretically they should.

[@TechIngredients]

That specification is from the manufacturer. They are consistent with their competitor's specifications for a similar product. The additional questions you ask might be put to them. The specification I am referring to is not for the purposes of trying to impress anyone, but as a reference. In view of the double pass nature of these panels and the practical limitations of real world space constraints and costs, this design seems reasonable especially if we are aware of what it's limitations are. The remainder of your comment is interesting and I would agree.

[@rronaldreagan]

Jim Brown 1 question, how bad is this foam pannel regarding accumulation of dust and the easyness to clean/vaccumclean it? I have several friends very allergic to dust and after the 1st year of use i think these pannels would accumulate so much dust in its pores it would be a nightmare for them to be in a small room

[@steveroberts7143]

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.

[@Godshole]

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

[@JakeWitmer]

...You probably just haven't met any virtuouso recorder players.

[@jasonbothun1]

Some of the most worthwhile content on YT and world's coolest Dad!

[@daveb5041]

*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* !

[@PongoXBongo]

3M = 3 Marriages ;)

[@laurabrown3007]

Acoustic Foams are used for Echo & Acoustic Curtains are used for Soundproofing SoundProof-Curtains.me

[@bombslap]

Thanks I was looking for this. The family has been restless lately

[@Musicguy1161]

Thank you for your informative and clear videos! You have helped me think through and solve a variety of problems or issues I have encountered lately. With regard to some posted comments that follow most any video, including yours, I would offer the following observation. Many people will line up to criticize videos or to offer "corrections" under many names, but you take the enormous amount of time, energy, knowledge and the at times not insignificant expense to post your videos while the vast majority of people with a better way of doing these things do not. Thank you so very much from so very many of us for taking your valuable time and resources to freely share your knowledge with the world, I can only hope that you continue to do so for any long foreseeable future. You are a great educator and no doubt a great man as well.

[@TechIngredients]

Thank you! You are correct. I'm open to corrections and criticisms, but only with data and sound principles to support them. Nothing we do is perfect, but it is the result of pretty extensive knowledge and research and when we do something wrong we try to explain why.

[@emmanueloverrated]

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.

[@laurabrown3007]

Acoustic Foams are used for Echo & Acoustic Curtains are used for Soundproofing SoundProof-Curtains.me

[@gerryk3114]

When we tested our speakers without an anechoic sound chamber be ran our frequency curves open air ! We dug a hole outside in the field, placed the speaker under test in the hole facing up towards the sky and placed our Bruel & Kjaer microphone 1 meter above the speaker on axis !

[@GerardPinzone]

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

[@b5a5m5]

RIP

[@sherman5k756]

Jajajaja

[@fire.5903]

mmmmm, that's a whole lotta *a s p h y x i a t i o n*

[@serasane]

Why not hydrogen gas?

[@cia9315]

Why not chlorine gas?

[@TheChillieboo]

just watching some older videos, and dude, you got some chops with a router! casual straight freehand cut

[@freesaxon6835]

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

[@freesaxon6835]

@@user23867 🤔😎

[@DasMrOSi]

"Fools, " said I, "You do not know Reflection, like a cancer, grows

[@sorin.n]

"I see what you did there" :)

[@tonysouthern3017]

For the words of the prophet are written in the KZbin comments, and the subsequent replies, to improve the sound of silence.

[@russellborrego1689]

You are an excellent instructor, I sincerely hope you're a teacher/professor or working for NASA or anything in your professional life where your skill is improving our species. Some people are just naturals, you are certainly one. Also, the 3M super 77 is the devil with prolonged exposure inside. A friend of mine and myself had a bad experience one night using it in a 15 x 15 room. Great suggestion to encourage people to use it outside.

[@radiowallofsound]

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.

[@GregJoshuaW]

I realize you have a ton of comments now so might never see this, BUT, WITH HIGH HOPES: How would you manage the noise generated by a diesel generator? Whole house generators make a heckof noise epecially as the nuisance adds up over time. Would you use an anechoic chamber? Some other sound baffling? You expertise with sound I think positions you as an expert to address such things. Thanks for all your brilliant and well explained content!

[@ellef9331]

"The neighbors really like this." Thug life!

[@raygirard9237]

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?

[@runklestiltskin_2407]

Your videos are gold.

[@TechIngredients]

Thanks!

[@redapproves1330]

I woke up Saturday morning with lots of notifications from work, friends, and fav KZbinrs. As a matter of priority, I enjoyed Tech Ingredients' newest content to start the day.

[@TechIngredients]

Thank you!

[@jimmybleron4700]

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

[@laurabrown3007]

Acoustic Foams are used for Echo & Acoustic Curtains are used for Soundproofing SoundProof-Curtains.me

[@majindermajorminor3919]

I appreciate your commentary at 25:27 where you describe how to place these panels for best effect. Other videos suggest covering 40-60% of the wall surface with panels. Your approach will use fewer panels and is more likely to get approval in this household.

[@hoglundh]

Love the screaming!!!

[@laurabrown3007]

Acoustic Foams are used for Echo & Acoustic Curtains are used for Soundproofing SoundProof-Curtains.me

[@kabevis1]

Channel is growing fast. I always appreciate the detail of your science!

[@andyb6120]

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!

[@kengamble8595]

This is another example of why your channel is growing so fast, very good videos ! 😊 Thanks for sharing and take care. 👍 👍

[@andysummersthxcinemaandmyc7748]

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

[@jimvanm]

Plus TOSLINK cables with the gold connectors!

[@speakersr-lyefaudio6830]

I’m an audiophile and am here for cheap room treatment. Audiophile isn’t always synonymous with snake oil, though to be fair, there is a lot of snake oil in the audio industry.

[@joaowiciuk]

I really appreciate your methodology when making videos

[@TechIngredients]

Thanks!

[@craigsummerville8823]

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.

[@pintfetzer3461]

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

[@palpytine]

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

[@KingHalbatorix]

Wouldn't have it any other way

[@theatre_pigs]

Actually, I just wanted to see him tear around in that dune buggy!!!!!

[@flow5718]

This channel is so full of good info, father and son both are great to make this happen

[@TheElusivePanda]

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

[@BenjaminT.Minkler]

for the panels I'm making I got printed fleece photo blankets for the covers ...I had some nice photography art in high resolutions and did a layout of a few different sizes on two of the largest blankets they made, then cut them up, leaving extra boarder around each photo to stretch and staple onto the backs of the sound deadening frames ....I was really pleased with the color and quality of the printed blankets, I found the cheapest price by ordering online from Walmart, but they do require very high resolutions (I havent built the sound panels yet, but did go ahead and hang up the photo fleece for now)

[@HarmanRobotics]

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.

[@debtminer4976]

Paint would be much quicker too..

[@TechIngredients]

You're right. Paint will seal the surface and glue will also strengthen the panel. The paint will cost a lot less. The wood glue will cost a little less.

[@debtminer4976]

@@TechIngredients paint would also make the panel rigid. Take it from a guy who forgot to wash and bag up more than one paint roller 😆

[@arfink]

The paint would also have the advantage of being easy to spray, which would take the job from being several messy minutes with a paintbrush to a few seconds with the sprayer. It would pay off if you needed to do a lot at once.

[@russellborrego1689]

I immediately thought of spray paint or shellac in a rattle can. Holding at a farther distance from the piece would help it be drier by the time it lands on the surface and not soak in as much.

[@InssiAjaton]

Around 1963 we undertook a task to improve the acoustics of our campus studio room. No money, no way using materials that cost anything. And only limited improvement in mind. What could we do? We found a number of large egg crates (I think they may have been 8 by 8 egg size) made of wood pulp. That was before all the plastic invasion. Worked like a charm. But when the studio was moved to a brand new building, the people who had to remove the flimsy material glued to the walls and ceiling were not happy.

[@jeff5702]

1:18 such a mood

[@powerofdreamx]

I really appreciate the details and scientific approach shared in your team and your videos. Some other sources leave gaps.

[@victormgv]

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

[@resonence1]

This is the single best video on DIY acoustic panels I've come across! Thank you.

[@kidcremezoo]

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.

[@TechIngredients]

The sound waves do not slow down. The pressure waves will reflect from the epoxy composite just as they will reflect from the wall. Retaining the fibers with a cloth is a viable alternative, however placing the panel in a frame reduces the absorbtion because the sound reflects from the wood rather than being absorbed by the panel's edges.

[@thomasjouanjean962]

@@TechIngredients Sound waves *do* slow down in Rockwool/Roxul (etc.) and other resistance to flow panels. It's due to the... actual resistance to flow/friction against the micro fibers that convert kinetic energy into heat. No resistance = no slowing down = no absorption. It is not a linear function, but is fairly easily predictable. Increasing surface impedance / resistance to flow with a product like exopy is a bad idea - high surface impedance will simply reflect a lot more sound, just as using too dense rockwool/roxul will as you increase overall impedance. It starts to act like a bandpass filter. The flow resistance properties of such materials has to be very well suited for a given application. When this factor is not known, weight will be a good indicator. Generally speaking and contrary to what a lot of people think, lower densities will work better for Low Frequencies as the depth of the panel increases (and/or target frequency decreases). Edge diffraction is only a minor issue affecting wavelengths smaller than the actual frame. On the other hand, placing resistance to flow panels (rockwool, roxul) against a boundary like a wall is severely reducing their efficiency as near boundaries there is little to no air particle velocity (its all pressure there) hence less friction = less absorption. As Kid Creme suggests, at a given depth placing them *away* from boundaries will substantially increase their performance. Near a boundary, it's all pressure and membrane based absorption will be the only thing really efficient. Also, pay attention to the Schröder frequency (when wavelentghs approach the dimensions of the room) as below the knee in the function, behaviour of sound shifts from specular reflections (behaving in a similar fashion as the Snell-descartes optical law) to purely a pressure behaviour, at which point resistance to flow absorption becomes pretty much useless. Hence in Anechoic spaces, the volume of the room has a lot to do with its cut-off frequency. The way the wedges are designed in a (real) anechoic chamber is such that it optimizes impedance matching.

[@rafaelcordova438]

@@thomasjouanjean962 i'll prolly need the rest of my life to understain what you just said. But thanx anyway

[@MrEazyE357]

Don't know if you ever saw this but a guy on reddit made DIY acoustic panels from wood frames and old towels and they outperformed commercial acoustic panels (acoustic foam, etc). It was pretty cool.

[@TechIngredients]

Yes, we did. DIY Perks did such a video. Because it's interesting, we plan to do some comparative testing in the anechoic chamber.

[@TexasScout]

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?

[@TechIngredients]

That's true.

[@bjeffrie22]

Yes but you need to be aware of the acoustic properties of the covering. Painted canvas ("real" art) - pretty reflective; speaker cloth - acoustically transparent but limited "art". Other choices somewhere in between.

[@np8781]

@@bjeffrie22 Even a solid colored fabric may be enough to look nice and blend in with the room more.

[@gregfeneis609]

Yes, similar is often done in large public venues such as libraries, theaters, restaurants. Sound damping panels (baffles) are suspended from the ceiling, and/or hung on the wall. What you see are rectangular swatches of decorative fabric, what's behind or inside the fabric could be various materials such as shown here in this video.

[@davegeorge7094]

Excellent video, showed off the quality of your video, audio, product. I have the best speakers/amp HD screen and noticed the audio range and ambience of the outdoors. Reverberation from the distant objects etc.. Very cool so now I must upgrade my music studio. I have many foam squares from hard drive shipments from past 40 years, the foam deteriorates as cell particles falling off continuously, some binder must be found. I place speakers on high room corner shelves to magnify off the three hard surfaces inches from source so the distant objects reflections are neglectable.

[@douggy3222]

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.

[@autumngreen86]

Really enjoyed the video. You took us from the tests all the way to building it. I loved every minute of the video.

[@fvu7296]

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....

[@mariusloubeeka5810]

You're right Fabian, a measurement with timing gate will work just fine outside. It even works good inside. That's how I do measurements for my YT channel. I recommend to use the free to test software ARTA for measurements and especially read its manual and the additional handbooks. Everything, even in what environment to measure, is described in there. Download at www.artalabs.hr/ For sound demos a normal room is okay. With a little bit of acoustical treatment to control reverbration time (T60) and set it to about 0.6 to 0.8 seconds will help.

[@Linktw0]

@@mariusloubeeka5810 thanks for reference to the info source, appreciated!! 👍

[@Linktw0]

Thank you for detailing the how the design parameters translate to accoustic properties. Im trying to find some "generalized theoretics" about accoustic design basics. perhaps you have any refs on where to find solid info? it'd much appreciated. (context for my question:) In preparation for a diy speaker build project, I'm currently just trying to self educate a bit before starting on a preliminary design, so that I can then build a cad model and take that to an actual sound expert to consult before i move to fabrication. Any links to good sources are welcomed, in particular if its design tutorial info. Thanks to anyone who can help.

[@mariusloubeeka5810]

@@Linktw0 : How about my tutorials? Please have a look here: kzbin.info/www/bejne/a3zZnWOfd7ZjgpI To get the fastest best possible result it is easiest to build a kit well thought out by a professional. The first few speakers you design completely yourself will not be very good because it takes years of experience to get it totally right. Until then maybe also have a look at some interesting kits I gathered together: kzbin.info/www/bejne/nX7cdmaJituGm68

[@ariellezen4683]

Could you give advice on soundproofing a vehicle?

[@rogerfurer2273]

Mid and high frequencies are fairly easy to deal with (absorption). Bass and low mids are much harder to address and are problematic in small rooms with low ceilings (less than 12-14 feet). A method for bass trapping I was very impressed with was developed by Tom Hidley. This is to hang heavy sheets of plywood a few inches from the wall that has the standing wave. The size of the sheet should be equal to the problematic wavelength, and the distance from the wall will affect the bandwidth (I'm not sure of the math for that). I once worked in a Hidley designed room with this treatment and it was an education in what a well designed control room should sound like. I noticed that the analysis showed mid-range peaks between about 450 and 600 Hz, and again from 800 to 1000 Hz. My suggestion is to try hanging some of your 2' x 2' panels an inch or two out from the wall and see if that reduces the lower mid peaks. 525 Hz is about a 2' wavelength. Just a thought.

[@32eoin32]

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?

[@probrhalo]

It will effect the sound absorption quality only a little at the end of the day you are mounting it to the wall and that will have a similar affect. It has actually been shown that putting a space say about half an inch between the wall and panel improves the absorption even further

[@collinrohwer1790]

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.

[@legendarysideburns2213]

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

[@McGutschy2]

Welcome to a world where the sonic boom is noise reduced. :) It will happen here or never.

[@fun_ghoul]

I mean, rockwool **is** fireproof... ;-)

[@legendarysideburns2213]

Gutschy maybe he could spray water behind the engine to cut down on noise, similar to what nasa does with their rocket launches.

[@mariohernandez1111]

@@legendarysideburns2213 that's not exactly the reason why they do that. The water spraying (deluge system) is there to capture the sound waves from reflecting towards the rocket, but they are still there. You are not going to remove the sound that way (if it worked, rocket launches would be much quieter).

[@BinjKomisar11]

I have heard through the grapevine that layering corrugated cardboard box material up to a few inches thick provides excellent acoustic muffling properties... The only downside (IMO) is the fire hazard. Awesome video.

[@TechIngredients]

Thank you!

[@Adenzel]

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 😂😂😂).

[@thatoneguy99100]

Honestly this is one of the best channels on KZbin.

[@TechIngredients]

Thank you! There is a lot we could do better and we're trying.

[@tenet-rotas]

1:20 now thats some quality meme material right there

[@collecter3456]

0x eac7 My exact thought

[@danchadwick1495]

When I was in Okinawa we lined a bunker with a double layer of pegboard, thus dramatically lowering echoes. Which were overpowering. The thought was to trap and cancel reflections.

[@Tyler_0_]

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

[@Tyler_0_]

nm, I guess some of those materials would flex and the ground would also reflect back the reflection from the material.

[@TechIngredients]

Did you noticed the frequency shift with the double layer? This is because the front surface is 4 cm closer to the speaker. The vast majority of the reflections are near field.

[@teamsleepnine]

this really helps, also you can't argue with this guy! he proved it scientifically

[@barabolak]

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

[@TechIngredients]

It's sitting next to the the turbojet flame tubes, waiting its turn.

[@barabolak]

@@TechIngredients Can't wait to see it perform!

[@stvcolwill]

@@TechIngredients That goes for probably all of your subscribers... we're all on the edges of our collective seats on the Magnetic Yoke project!!!!!!!!!!!

[@tims.2832]

Thanks for putting in this effort and sharing your results, that was almost a scientific approach.

[@blackturbine]

1:30 can we talk about his huge lung capacity

[@jonathanmathews7673]

I literally just made panels for my studio today when my friend send me this video. Back to the work bench!

[@DocMicha]

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.

[@kensmith5694]

Your explanation was clear to me and appears correct. Really you need random (or near random) shapes and angles to prevent reflections. Also having the wall (the foam mounts to) made so that very low frequencies can flow through the first layer helps. It is all about turning energy into heat.

[@TechIngredients]

You're point is clear. A better and simpler correction for this distributed reflection problem would be to apply a piece of flat foam to the flat rock wool panel. We should have done that.

[@TechIngredients]

You don't actually need random angles and shapes, but continuously varying angles and sizes will be superior as there will be no favored resonance frequencies or conversely, no favorably absorbed frequencies. This was a daunting fabrication challenge and we decided not to attempt it.

[@kensmith5694]

@@TechIngredients "continuously varying" can be understood to mean dimensions that go 1,2,3,1,2,3,1,2,3 etc. This ends up having a favored angle and frequency. BTW: I have commented at work "If this was easy, we wouldn't have a job"

[@TechIngredients]

Actually, it means something a little different than that. It means continuously changing angles as in infinitesimals or continuous curves. There should be no flat surfaces and the curves should not have a fixed radius.

[@ShaneCranor]

Awesome! I did notice a few of the inaccuracies in the DIY Speakers video. When you test your speakers in the Anechoic chamber please don't just hang them there. The wall behind the speaker is just as much a part of the speaker as the material you make it out of. I would recommend putting in some plywood or drywall to simulate what a wall would do to the sound and possibly experiment with the distance between the speakers and the wall! Love your videos!

[@TechIngredients]

Thanks! That's a good suggestion.

[@atech9020]

On your other video, I made a post ( under a different account ) about the " room " and how the readings you show are likely due to comb filtering. The measurement software you use is not ideal as it doesn't seem to have windowing or burst modes. The way you measured the panels in this case you still had a hard reflective surface nearby ( the bird box the speaker was in ). Also keep in mind that frequencies below about 500hz start to get omnidirectional, so the test mic could hear the direct sound, the reflected sound of the panel and the resultant reflection off the bird box again. You need software like Smaart that you can do impulse responses with that have windowed data collection and can eliminate some reflection data spoiling your measurement. The test you did was great at determining a material that reduces reflection though and making a panel with that will improve readings. I also want to say thank you and many Kudos to you for going above and beyond in order to give us quantifiable information and data to work and create with. The upside is you and the rest of us get to learn!!! The downside being that you could have tested your panels in a different way and come to more accurate and or at least more enlightening data. The DUT ( devise under test ) is often just a small piece of the pie when the testing format, software or equipment does not eliminate anomalies in the testing procedure. If you know what the problem is, often you can negate some of the bad data associated with it. Anytime you see a common occurring dip in the response, it is almost always comb filtering. Now, where that comb filtering is coming from is the question? Is it the DUT, or bad data from environmental influence? Speakers do have intermodulation distortion especially on larger panels, but you don't typically see that until higher in the frequency response. Typically this occurs where the area propagating the sound is significantly larger than the frequency of reproduction. As you have cleared up quite well in your other videos, moving the source of excitation ( offsetting the driver ) helps to reduce this phenomenon. A project perhaps for another time would be to create a two-way panel where the panel itself has a crossover to its driver and placed on the panel is another HF driver to take over just the higher frequencies? Just stirring the pot here a little :) I may perhaps attack a similar project like this on my own channel, but this is not what my channels is really designed around ( I am another talking hands type channel like AVe ) and displaying this type of content is beyond my current production ability. In short, you're awesome and I like what you're doing!!!!

[@serge..k]

What a lab outdoors! I successfully used the extruded polystyrene to turn one of the rooms into anechoic chamber.

[@SuperGokuSon]

I am constantly amased by how thuro you always are and the results are amazing...

[@endleontiozae7061]

"The neighbors really like this" gotta be the best part of the whole video.