How BASS Works (In Rooms) - Acoustic Geometry

[@locust108]

I like how I learned something and was sold an ad at the same time.

[@dimitriward1449]

😂

[@ianhosier4042]

I had a stupid cadburys ad - if their chocolate wasn't so bloody expensive I would buy it

[@Stan_the_Belgian]

😂😂😂

[@caiomeirinho6383]

YOU STINK

[@VictoryAviation]

This demo knocks it out of the park explaining the acoustic anomalies associated with smaller rooms. Thanks so much for putting this together.

[@BenBrossMusic]

As a musician who has significant hearing loss, listening to KZbin videos through earbuds for the last three hours, I'm struck by how clear and beautiful the sound of this video is compared to all the other videos I've watched today. Good to know there are people who understand and care about sound.

[@mrileeks]

The use of props in this and every other video has been astounding. Props to you sir!

[@johncalder8490]

Ha! Nicely played!

[@naKuhito]

I see what you did there

[@nicholashenry4133]

Like the irony👌

[@YellowWalkman]

Prop squared!

[@brianabbinanti7021]

Clear, concise, and easy to watch. Love it!

[@warpacademy]

Nice video production. I really liked the visual examples and education on how bass works in rooms. You've said that porous absorption is not effective under 200 Hz though, and that's just untrue. If that was true, and the only thing that worked were pressure-based treatments, then you'd never see professional studio builders filling their rooms with rock wool and fiberglass at depths up to several meters. Those treatments absolutely work, way down to 30 Hz, when you build them with correct depth and density. I can support that statement with a real world experience and acoustic testing data. It's definitely correct that as particle velocity decreases the effectiveness of porous treatments declines, that's why airgaps are used. Even without airgaps, fiberglass can damp room modes down very low in the LF. In my control room we have a front-back axial room mode of 35 Hz that we treated with 1 m of fiberglass and slats. The low end is completely controlled. And of course pressure treatments have their place and use. But it's off base to claim that under the Schroeder frequency you cannot use porous absorption. People like myself are doing it with excellent effectiveness.

[@musergio1]

Keep making these videos! This channel and the people behind it are amazing

[@Acousticgeometry]

We appreciate the kind words!

[@duythai5442]

Some of the very best demonstrations! Awesome work!

[@Acousticgeometry]

Thank you for the support!

[@StupidEarthlings]

I wouldn't really call this video "demonstrations" as much as pictures and graphs.

[@cptbamboo2217]

Studying audio engineering and this chanel is pure gold

[@murphyalvin1893]

Hey man, these are also extremely useful resources for studying the science of sound and recording if you're interested. kzbin.infovideos kzbin.info/door/N5UUY5P4IO1nCuQSfo-Uug kzbin.info/door/SCwzZX29jTILlsP4MhjQvg

[@cptbamboo2217]

@@murphyalvin1893 thanks bud!

[@michaelyolch79]

Holy smokes! An engineer with a sense of humor. Very rare! :)

[@Whitefox-pc7lp]

I'm constantly researching sound related information and so I'm glad that I found this channel!

[@sebastianlopeziii]

Absolutely brilliant!! John - thank you so much for your unrivaled advancement of acoustic education on KZbin. Bravo!

[@johncalder8490]

Thanks!

[@Zheartbeat]

Best Video I Ever seen on YT . Very well Explained Thanku So Much .

[@auxilix]

You described so many concepts so quickly and well thank you.

[@lebohang8405]

Thanks a million John, I saw one of your videos about speaker isolation a couple of days ago and I decided to test it. Went and bought rubber cushions for my mains and sub woofer. The difference is night and day. Magic 👌🏾👌🏾

[@steveg219]

Nice job on creating a brief explanation of a complex subject

[@Maynard0504]

I finally understand "bass precision". Great channel!

[@DrSamE]

Wow. A video that was actually good info! Props also to testing at NWAA labs, Ron is a valuable source of knowledge!

[@roitadmor]

The way you teach is very unique

[@SideGateStudios]

Love love love this video, well put.

[@larstofastrud1788]

at 0:45 the 6' tube resonance = 188 Hz at 1:46 there is a sweep from 188 Hz and down to 94 Hz The narrator says that below the modal range (188 Hz) bass can't fully develop while the video is very clear what happens. There is plenty of energy in the whole tube at 94 Hz at 1:52! Bass very obviously develops without any issue below the modal range. -There's plenty of bass inside a loudspeaker box. -We can hear the whole frequency range with earbuds, even if the modal range of the ear canal is at about 15kHz. 1:57 "the room crossover". This is the "transition range" (Schroeder frequency) and it indicates the area where the room transitions from Ray-based acoustics to the modal range where the sound is dictated by the room dimension. It is not "velocity based to pressure based" sound behavior. The pressure range is below the lowest mode of the room (the longest dimension of the room). Maybe what the narrator wants to say is that most typically, but certainly not all the time, it is beneficial to use pressure-based absorbers in the modal range. ...at least with regards to how much space the bass trap occupies. "Only accurately tested & lab-proven bass absorbers are known to work" That is a very strange statement. A Helmholtz resonator doesn't need to be tested for it to work. Just blow across the neck of a bottle... it works. Further: there's a reason why Sabine's numbers are just above 125 Hz (sometimes 63 Hz) and that is because, as the narrator said earlier in the video if a pressure-based absorber is placed in the wrong location, it has zero effect.

[@johncalder8490]

Hi Lars, thanks for your comments. When trying to explain complex topics simply, it becomes necessary to under-explain deeper parts of the topic; the goal of our video isn't a PhD. level course in room acoustics, it is an awareness that there is a lot going on at low frequencies in a room and that with some knowledge, reasonable choices can be made to improve one's listening space. The point of the Kundt's Tube demonstration in the video is that below the resonant frequency of that particular dimension, the wavelengths are too long to fully develop and as a result, the usual methods of absorbing sound to reduce resonance energy, which are wavelength-dependent, are far less effective. Of course there is energy in the room from the speaker or instrument - the point is that to control resonances, different methods must be used. Many research resources use the terminology "velocity-based" and "pressure-based" - I decided to go with those terms. Yes - there are other LF absorber choices, but they all use much more space and can be unpredictable unless fully tested in an acoustics lab accurate down to the target frequencies. As for Helmholtz resonators, I have two problems with them: 1) as air conditions (temperature and humidity) in a room change, so too will the resonant frequencies (speed of sound varies by temp...) - will the Helmholtz resonator track those changes linearly? 2) More importantly, why would anyone add a new resonance to an existing resonance? Sound transients will be destructively affected. Well-designed and accurately-tested membrane low-frequency absorbers work, and if properly placed, remain the best choice to mitigate room modes, IMHO. There's a lot of misinformation and bad or non-existent "bass trap" specifications in the marketplace; there are test results from laboratories that cannot be accurate below 150-200 Hz due to Schroeder frequency test room size limitations. I'm confident that more information, even if condensed into short videos like this one, is helpful in making purchasing decisions, whether for our products or for other manufacturers. I wish the industry would get its' act together and insist on accurate product testing and specifications for these areas. Thanks again for your insightful comments! John

[@caseym6272]

Found your videos recently and I gotta say, I appreciate every single one of them. It's so cool and informative!

[@Pippo.Langstrumpf]

Great description. Thanks

[@YellowWalkman]

This video is actually phenomenal. I learned so much knowledge!

[@pingfunk]

Graham Hancock is schooling us on audio now too

[@tungbif]

Great videos! Informative and made easy to understand. I'd love to see a video about the acoustics in a round room. I have a such room with a sound system and I'm having a hard time to understand how to manage the acoustics. It seems like the sound bounces in an almost chaotic way to different directions.

[@KingOath]

It still works in a similar way to a rectangular room at low frequencies, except for the length and width are identical every which way, meaning there is one very strong horizontal room mode right in the centre rather than many weaker ones.

[@anunakigaviria1105]

YOU ARE THE BEST, THANKS FROM COLOMBIA.

[@kian3548]

I love how when he says 'bass' I imagine the word having an extreme bass boost to it.

[@SpacedOutDoonie]

This video got that 90's video vibe

[@VenVile]

This is brilliant and beautiful. Thank you!

[@GunnyPhillips]

A complex topic for sure but this helped me greatly. Thanks!

[@oldmal60]

Thank you. I learned something here can use. Plus your product looks good for my very small need.

[@johanvanhuyssteen9217]

Awesome video. Thanks for sharing.

[@nkemebenezer]

This video is very helpful. I have learned so much. Thank u lots and God bless you Sir

[@unclejamesx9808]

Wow thats some informative stuff. Thanks

[@keepitup3545]

Thank you so much to be with us ❤️💖

[@Arabesque_1220]

yoooooooo this is actually insightful. nice work!!!

[@babloovyas1080]

Thanks to you for explaining all these facts.

[@drnandakumarakvelu1581]

Real Sounding Video.from massive Efforts..Thank you

[@krsticmilosh]

Thank You this is fantastic video both as knowledge and study.

[@ydlp7705]

Yeah science experiment with imperial system.. Gotta love laws of physics!

[@22strong4you]

Please use the metric system. Thanks

[@blancasusanamariles4655]

2021: Acoustic Engineer consultant Designed my music room w/grand pianos(2) 25x35'. It is not s rectangle but has built up corner absorbers; w/Glass Blocks to absorb 50% Street bus noises. Sound travels 100'/sec

[@andyh8239]

Absorbing the room effects... Does that also increase the sound pressures in certain areas that were otherwise cancelledbout by a room effect? I.e. Lower spl at resonance, and higher spl at a null?

[@sstefanos00]

Exceptional video! But what have "I" learned??? That I am not going to be able to sound treat my living room unless I buy expensive accoustic panels that must be placed by expensive specialists who know what they are doing....Oh well...

[@johngarbutt]

I agree. Interesting video but no help whatsoever with setting up my hi fi system and in particular my sub woofers. well its back to good old trial and error for set up.

[@jasonLJ]

​@@johngarbutt just buy reputable bass traps, the more the better basically

[@krismichalsky]

@@johngarbutt I agree guys, there is some nice knowledge in here, but as for me and my setup, this doesn't really do much for me other than to play around with my own testing of acoustical materials and where place them in the room and then for the hours of listening tests as in A to B and back to A....

[@TroysGarbage]

I think this video is marketing targeted to the very specialists you mention.

[@chrisw5742]

@@jasonLJ bassically

[@artvandelay4914]

awesome video

[@CoreZeroStudios]

This is a great video I sent it to my audio engineers! One of them asked what happens with bass in headphones or earbuds. I know this is not the area that you specialize in but can you think of any place that would cover this topic? Obviously aside from KZbin. Thanks!

[@robduff]

Given all this information. What would be the ideal dimensions for a home recording studio?

[@ChrisClark_808]

I just go sit in the corner and wish the whole room was that loud. 😂

[@PerpetuusTenebris]

Same! (Fun fact, by the way, if you put a sub in and facing a corner with an obstruction (like cabinets) a few feet above it, the output is greatly increased throughout the room with fewer noticeable modes. It's the same with putting it under a desk or something like that. The modes even out to give more accurate output. Why do I know this? Testing! How does it work? Reverb I guess. I don't know.)

[@kingdavidakinyemi]

I love this so much!

[@norvillerodgersspeaks]

brilliant video.

[@euphoriamusic9802]

very informative , thank you

[@jasonvotaw5966]

Love the action man props!

[@SoundUnitedTraining]

Great video! Very informative and easy to understand.

[@timmypena241]

You’re an internet hero.

[@joshcrowe9105]

Awesome content! By chance could you do a video on a round room? Or a Yurt Shape? I am helping a friend build a Yurt recording Studio and struggling to find much information on the general acoustic response of the rooms. Thanks for any help and the great knowledge you've put out! Cheers!

[@johncalder9188]

Round is the second worst geometry for a sound room after sphere. It hugely magnifies one or two frequencies beyond repair. I'd advise against it. Thanks, John Calder

[@Frietpan]

when i look at the room correction results on my avr i can see there is a huge dip in response at around 80hz from a bunch of channels that dip also did not get corrected by the room correction. is that a room mode problem or a null as the video talked about?

[@chawlamohali]

Beautiful!

[@jcisme]

So these are a broadband membrane absorber ? I thought membrane absorbers only worked in a very narrow band and need to be build to for the room after extensive testing ?

[@TriPham-xd9wk]

Would sound high intensity create tsunami too? Possible and by superposition freeway and drainage design accurately could be able to generate tsunami from freeway traffic

[@omegahyperes96]

For the love of awesome sound, thank you!

[@gaetanobruno5889]

amazing video

[@neolyth]

Love this video, thank you

[@CobraChamp]

Do your bass absorbers absorb evenly at all low frequencies or do the target the resonance frequency of the room?

[@mortaldread9379]

Awesome - I'm sold :D

[@audfrknaveen2256]

Hi ....is the soft copy/digital copy of the book MODERN ROOM ACOUSTICS is available yet ??

[@kloss213]

You can use multiple bass systems distributed around the room this allows a more even frequency response.

[@InsaneCarville]

Why wasn't this uploaded when I was treating my room for university studies over 2 months ago hahaha. Thank you though, informative as always.

[@CobraChamp]

This is a great video breaking down the complex topic. I just wish you'd have given credit to the proper name, and credited the discoverer, of the Schroeder frequency.

[@basscleaner]

No doubts, room dimensions are critically important for good sound reproduction, especially for low frequencies. Nevertheless, if we have the limited space of variables, which fully determine the sound result, it means, that among possible room dimensions for known low frequencies source position (height) there are the best, the worst and medium sets of such a room dimensions. The best room dimensions set for low frequencies is understood like for having minimal spread for amplitude-frequency dependence in range 20 - 150 Hz. Corresponding to this thesis, we can have (or not!) so-called Acoustical Dimensions for this room. Do you agree?

[@chotafallen8390]

Good explained. Next time turn volume in your record much more up. the annoying sound is not loud enough.

[@freereacher]

Excellent!

[@PotatoflakeJake]

GOD YESS CANT WAIT TO WATCH EVERY FKING VIDEO YOU HAVE THANK YOUUUU

[@thomasriis1987]

Thanks Graham!

[@undercrownhiphop9422]

aren’t membrane traps more targeted for a narrow freq range?

[@awookieandagerman]

Cool video! I wonder if you can talk about some design solutions to these bass problems. Like, what would be the ideally dimensioned room for accurate bass? Or what about a room with no parallel walls? Would that make it easier to achieve accurate bass? Could the walls be fitted with textured shapes that disperse sound, or would it be better to just have them angled away from each other, or maybe both?

[@matsudakodo]

To answer that, you have to know ahead of time where the speakers and subs will be placed before the room dimensions can be optimized. See Floyd Toole.

[@johncalder8490]

Thanks for your questions! Designing a room without parallel walls and non-parallel floor-ceiling geometry is a great partial solution, and many recording studios and high-end listening rooms do just that. But volume-based low frequency resonances (the same effect as blowing across the top of an empty bottle) will continue to be a problem. Also, due to room crossover, there are no diffusion treatments that will diffuse wavelengths longer than the room dimensions. The best solution to room modes and bass resonances will include combining effective low frequency absorbers with optimal room geometry design (as well as optimizing speaker placements).

[@awookieandagerman]

@@johncalder8490 Thanks for the answer. Is there a program you use to determine optimal speaker placement and absorber placement in a given room? Also does room crossover cease to be a problem if your room is large enough to contain any anticipated bass wavelengths?

[@snapascrew]

Kinda want to take my homemade tube traps to that lab and have a full test day hahaha

[@christianocean8998]

Amazing !!! The bass is always a problem in the room ... Which is the best bass trap to use in a small 17-18 m2 room ? Thank you

[@johncalder8490]

Hi Christian, thanks for your question! The room modes present in your room would depend on the room's dimensions - how many meters wide by length by height. Divide each dimension by 331.5 (speed of sound at 21 degrees C.) to give you the approximate modal frequencies for each axis (width, length, height). These "Axial Modes" are where your strongest mode additions and cancellations, depending on location in the room, will occur. We prefer to treat low-frequency (LF) modes with broadband absorption (we also prefer not to use the term "bass trap", as it has been widely misused). The combination of our two membrane LF absorbers work from about 45Hz to above 250Hz, fairly efficiently - the ratio of Curve Diffusor (each of which have a built-in LF absorption MLV membrane) and the CornerSorber (a dedicated LF corner membrane absorber) is about 3-4 Curves for each CornerSorber pair. When properly placed at 1/4-wavelength (room dimension) locations along each wall, Curves work very well to diminish modal energy. The CornerSorbers are placed in any room corner. I hope this helps! Thanks again!

[@ahmedzengy]

How can i calculate L shape room mode?

[@manhuawang11]

Figuring out bass at NWA labs? I'm down with that. Can they measure out my six-fo?

[@johncalder8490]

While NWA did have some awesome bass, NWAA Labs in Elma, Washington is the best place to test bass absorbers and other acoustical products. 'Prolly can't do the six-fo tho. Maybe could measure the car's engine sound...

[@victorygah]

So cool! Thanks. Where I can learn about this?

[@caspermaster-com]

When you say velocity based absorbers (fiberglass and rockwool) aren't effective under 200, do you mean not effective at the same depth as pressure based absorbers or do you mean its inefficient use of the space in the room due to the depth you need for them to make a difference, or porous absorbers cant do under 200 hz even if they are a meter deep?

[@johncalder8490]

Thanks for your question, Casper - It's a good one. Fiber-based absorbers (and obviously foam) are ineffective compared to the relatively small size of membrane absorbers; fiber is also less efficient under 200Hz than membrane absorbers; and fiber must be placed in the additive mode points (the anti-node) to be somewhat more effective, which is usually in the useful space in a room. The "original bass traps" were designed by Tom Hidley to be used in high-end recording studios . They were about an additional 1/4 the size of the control room space (my estimate) and were an entire small room filled with fiberglass (lining the walls and covering a large number of "blades" hanging from the ceiling, with a slot-type "port" opening). These were effective, but obviously used a huge amount of expensive real estate. Properly designed membrane-based low-frequency absorbers (I really don't like the term "bass traps") are more efficient, are best used at boundary surfaces (thereby out of the way without using valuable room space), and end up being cost-effective.

[@bartvanransbeeck1341]

Some engeneer told a solution to avoid room issues on bass response is to put a line of bass speakers on 3/4 of roomhight....Infinity IRS applied this with their 6 x 12" bass speakers ....?!

[@paulsarodh5460]

Superb

[@Borderlands808]

Anyone know what happened to “directional sound”? As in only people in front of a speaker can hear what’s coming out of it.

[@christiantorma2440]

sehr sehr geiles Video 😎🤘😎🤘😎🤘

[@marcaoliver2965]

Just curious, how does different densities of walls affect the sound, like is are hardwood walls and floors perhaps better than concrete floors and sound dampened drywall, like is there like a preference or just whatever is easiest to control in general is the goal

[@johncalder8490]

Good question! There are differing views, of course. To control low frequencies in rooms, some people hold that the most-dense wall structures are best, some believe semi-resonant drywall structures are best. My own preference is for solid non-resonant walls because it is very difficult to predict how a drywall or other non-dense structure will behave after installation. The stud centers, number of screws and their tightness, whether multiple layers are used (and if Green Glue or similar is used), and other construction variables seem to argue in favor of solid, dense, and isolated walls, ceilings, and floors. Then accurately-tested and effective low-frequency absorbers should be used to mitigate room modes. IMHO. Thanks for asking!

[@williamchen454]

What problem does the room crossover cause in practical terms? Longer decay times? Problems with amplitude?

[@johncalder8490]

Below room crossover, using fiber-based absorbers is far less effective for absorbing low frequencies than using membrane LF absorbers. The room mode resonances which are responsible for room crossover cause much longer decay times at and around the modal frequencies, which also results in widely varying low frequency amplitudes at modal frequencies at different dimension-based locations around the room.

[@keepitup3545]

Love you sir ❤️❤️

[@mr.wolfbeats3883]

Thanks for sharing! You're awesome

[@Sykologist_Music]

Nice infomercial! I’ll consider buying two of those if I can afford em.

[@drsumantamajumdar2771]

Brilliant !!.. Thank you Sir !

[@Akshaibiloniya]

This video is like a bass poetry. ❤️

[@Tatonka88]

I’m going to maybe build a studio that is 20 ft L x 7 ft 5 inch W x 6 ft 7 inch H. Is this room treatable?

[@johncalder8490]

Hi Riley - Oof, that's a tough set of dimensions. Too narrow, a bit too low. You'll need more treatment than a wider, higher space because the side and ceiling reflections are close and the modes are higher in frequency than "normal" dimension rooms. Best of luck - some rooms are problematic, this will be one. Not unworkable (hits have been made in "bad" rooms...), but not ideal. You might consider a fair amount of effective low-frequency absorption in the rear of the room. And cylindrical diffusors along both side walls (especially in the front half) and front wall. Fair amount of (at least) 2"-thick fiberglass absorbers as well, in corners and between some of the diffusors. See our KZbin video "Acoustic Panels - What & Where" - here: kzbin.info/www/bejne/l5zMiKRvbMmGeKM.

[@locmanw1583]

I live on the top floor of a 4 story building. Does bass travel to the floor below into my neighbors suite?

[@johncalder8490]

Yes.

[@locmanw1583]

@@johncalder8490 ok thanks 😊

[@endezeichengrimm]

What are they still using feet?

[@arjunxchauhan]

Nice done lads

[@santoshgujar5237]

Thank you, Sir

[@adamskatharakis653]

Good selling skills-- I'm totally ready to buy me a nice set of bass traps, even though I only use headphones. ;-)

[@andynonimuss6298]

Room Null locations: 1st Harmonic Null = 50% 2nd Harmonic Null = 25%, 75% 3rd Harmonic Null = 16.7%, 50%, 83.3% 4th Harmonic Null = 12.5%, 37.5%, 62.5%, 87.5% 5th Harmonic Null = 10%, 30%, 50%, 70%, 90% 6th Harmonic Null = 8.3%, 25%, 41.7%, 58.3%, 75%, 91.7% 7th Harmonic Null = 7.1%, 21.4%, 35.7%, 50%, 64.3%, 78.6%, 92.9%