Experiments with $100,000+ Speakers

I joined SoundField to experiment with the powerful speakers at U Street Music Hall!
Check out SoundField! • From Chipmunks to Auto...
You can learn more about CuriosityStream at curiositystream.com/physicsgirl
Join Physics Girl and PBS Digital Studios' new show SoundField as they experiment with giant $100,000 speakers and aim them at your body parts looking for resonance, at oobleck, at googly eyes, and at candles to explore the physics of sound.
If you liked this video check out these:
How I broke a wine glass with my VOICE
• How I broke a wine gla...
5 weird ways to put out a candle
• 5 weird ways to put ou...
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Creator: Dianna Cowern
Editor: Levi Butner
Research: Imogen Ashford
Sources:
www.washingtonpost.com/blogs/...
ore.exeter.ac.uk/repository/b...

[@physicsgirl]

Some people in the comments (hey people!) have stated the Tacoma Narrows Bridge collapsed due to aeroelastic flutter rather than resonance. I found this idea really interesting and it took me down a rabbit hole of nuanced physics. There’s a common misconception that the bridge collapsed because of resonance in a particular way. Namely, that the wind pushed, then stopped, then pushed, then stopped at just the right rate to match the natural frequency of the bridge. This did not happen. What happened is that relatively steady wind pushed on the bridge, the elastic properties of the bridge caused the bridge to twist/sway, and that process repeated, and occurred at the natural frequency of the bridge. This is an example of a process called self-oscillation, and the self-oscillation that resulted was at the natural frequency of the bridge. This is quite different from “forced resonance” where the driving force is at the same frequency as the natural frequency of the system. The question I’m considering is whether the bridge scenario can be considered a type of resonance. We call it “resonance” when you blow into a bottle and it whistles. In that situation, there’s no periodic driver. There’s a constant force, just like with the bridge. Some of you mentioned MinutePhysics’s video on this. I’ve texted Henry! (Henry is MinutePhysics). I’ll keep you posted on what he says.

[@firefish111]

Et voila, that's how you get a broken bridge. The footage even looks edited ¯\_(ツ)_/¯

[@crashwelder5337]

the speakers literally blew out the candles because they are pushing air. it is not the sound waves themselves. try 5hz in a small confined space. you will feel it in your gut

[@tfofurn]

See also Practical Engineering's video: kzbin.info/www/bejne/o4m3hKGQnNeZrq8

[@katzen3314]

I think it definitely counts as resonance- An excitation at a system's natural frequency causing oscillations with a diverging amplitude. It's not quite the same as flutter, as the vortex shredding causing a periodic driving force on the bridge would occur even if the bridge remained stationary.

[@jmunt]

@@crashwelder5337 umm... sound literally IS waves of air (or any material, technically) being "pushed" or condensed. So yes, the speakers pushed the air to create sound waves which put out the candles.

[@waynowayman]

"I was hoping my eyeballs would pop out of eye sockets, but....it was disappointing" Lol

[@michaelskinner3738]

Mine Would.

[@Yalikejazzboi]

( ͡° ͜ʖ ͡°)

[@SheeplessNW6]

How metal is that?!

[@erblinbeqa6550]

Kakashi's eyes

[@suzannestrickland1586]

I also loved that comment. I would probably have hoped the same lol.

[@itsnotyasir]

Me: My house is on fire. Dianna: Hold my Speakers. *Drops some sick beats* *Fire stops*

[@paulleimer1218]

Dang bruh, this beat is anti-fire

[@bloodaid]

Took the fire out the house and put it in the beat

[@alveolate]

Me: drops some sick beats House: i'm on fire

[@itsnotyasir]

@@alveolate House lit. Speaker lit. Fire lit. Beats lit. Someone call 911.

[@vigilantcosmicpenguin8721]

Fighting fire with fire?

[@griever2017]

Dianna really proud of that one breaking wine glass video :P

[@BothHands1]

Griever i don't blame her, that was freakin awesome

[@potatomaster9391]

Yep tahts true

[@physicsgirl]

It's my favorite child.

[@luismijangos7844]

I show that video to my students every semester since she published.

[@MrNoName7474]

I would be proud too! I'd try to learn that skill myself, but I don't have any wine glasses to break :(

[@candykanefpv98]

Fire is commonly also put out by explsives. The explosion displaces enough air that it snuffs out the flame.

[@yunclehead]

I don't know about them explsives, man. I'll cuss a fire out, but it'll keep burnin'.

[@amehak1922]

It's the pressure wave

[@thomas.02]

fight fire with kind-of-a-fire-but-more-expanding-gas

[@candykanefpv98]

Thomas Chow well, the explosion uses up most of the oxygen in its own fireball.

[@professional_silent_trumpe1540]

Then how do you explain burning Godzilla?

[@vasantjoseph]

I did my final year project on this topic!!!! Fires are not put out by sound directly!!!! Infact the vibrations from the sound create a vibration in the flame..which causes the fuel to air ratio to decreses...and thereby cutting the supply of oxygen to the flame material!!! Its kinda like how we blow out a candle..but in a larger scenario!! Optimum frequency desired for extinguishing fire is a low frequency sound in the range of 80 - 96 hz

[@DaviddeKloet]

I was confused because I could easily hear the 15 Hz sound. Then I realized I was watching at double speed.

[@physicsgirl]

THAT is amazing.

[@antogameseng744]

Literally just happened to me. I watch everything in 2x speed.

[@fustigate314159]

I can't recall the equation, but increasing speed affects tone.

[@dscrive]

Thank you sooo much. I didn't think to switch back to 1x when I heard the sound. Edit: Confirmed, I can't hear 15 or 20 hertz at normal playback speed, I couldn't make anything out at 40 hertz either.

[@DaviddeKloet]

It's interesting because KZbin (or the browser?) does a fancy transformation to make normal sounds not become higher pitched at higher playback speed. But this apparently doesn't work for sound at such low frequency.

[@marijnpater]

3:42 it also depends on the KZbin compression. So because of the compression you can't hear low or high frequenties

[@ChickenManiac]

i was able to hear 20 hz but nothing below that

[@bearb1asting]

@@ChickenManiac 😂😂😂😂😂

[@andymcl92]

Also the reason that ASAP Science's video about hearing doesn't work. The high frequencies were totally removed and replaced with a buzz.

[@MegaAstro3]

I could hear the 5 hz lol

[@woopygoman]

Pretty sure most compression algorithms start at 0 Hz and go up to the sampling rate (44.1, 48, 96, etc...). There's still some info that can be conveyed under 20 Hz if you have the right gear. Besides, lower frequency means less sampling points which means less data. Adding the chunk between 0 & 20 Hz adds a negligible amount of data. Nyquist-Shannon to the rescue. #RedBookCDIsAllYouNeed

[@Manzzzzzz]

Put them near the saturn v (over 200db) It was so loud that even some structure were damaged from several mile away....

[@candykanefpv98]

Structures being damaged would be as simple as windows being broken. Obviously it wouldn't rattle apart a house that's miles away.

[@Manzzzzzz]

Echo yes,sure. But near it the sound is so intense that can kill people instantly

[@candykanefpv98]

@@Manzzzzzz yeah, that's why they evacuate the buildings that are within the immediate viscinity of launch sites. A because it's really loud and can destroy stuff and injure them. B because it can explode and they'd be close enough for shrapnel. Like, there are workshops right next to the luanch sites at vandenberg and cape canaveral.

[@davetoms1]

*Dianna:* I want to use hugely powerful speakers to recreate the effect that lets a voice shatter glass and wind demolish a concrete bridge. But on my body so I can feel it too. *Me:* Wait, Dianna don't you know that this could... *Dianna:* 4:22 "I was hoping my eyeballs were just shake and pop out of my eye sockets... but it was disappointing." *Me:* ...never mind. You totally know. Damn, Dianna! Your dedication to physics is terrifying but inspirational.

[@DJlegionuk]

I can tell you when I DJ at a club my eyes can vibrate on some tracks 100%. Mythbusters did the brown note episode and had specially modified speakers from Meyer sound, perhaps get in touch with Meyer and see if they can help ?

[@mrepic789]

gotta love meyer arrays ;)

[@thryduulf]

We accidentally discovered the resonant frequency of the school stage at gig we organised there - it's the same as the dance to Saturday Night by Whigfield (which was current then) - a line of people in front of the curtains all in sync makes the stage visibly resonate hard enough to move a rock band's equipment including speakers and full drum kit!

[@uweihai]

“Make body part resonate” Me thinking people blowing up for some reason

[@TheWormzerjr]

Girls like to ride harleys and sit on washing machines for a reason. click my name to watch Son of Perdition part 4. or watch all parts if you arent convinced

[@Szobiz]

saaame LUL

[@IETCHX69]

I wanted to see her sit on her phone and keep pressing redial .

[@ameliagrrhairhoe]

I read that just after she said it

[@alveydoug]

Two things: A retired Rock an Roller told me they would adjust the subwoofers by how many folks were “tossing” their beer. And, Police and Military have speakers for riot control, that can make folks wet themselves (and worse). They’ve got those frequencies DOWN. They can also precisely aim the sound.

[@FelipeFigueroaG]

Dianna, for the next resonance video you should talk about the damping ratio in oscilating systems. It's not likely that your eyes are going to pop out even if you are exciting them at a resonant frequency, because all of the squishy fluid they're made out of is pretty capable of dissipating all of that mechanical energy (overdamped system).

[@JamesWilliamHoughton]

Maybe an interesting addition to this would be how frequencies affect and potentially damage hearing 🤷🏼‍♂️

[@mikeunivers]

the mid frequencies are the most dangerous, the high frequencies are almost inaudible and the low frequencies can be audible and inclusive you can feel them but if they are very low they are inaudible but you can feel them if they are strong enough.

[@HEYDJ]

Didn't expect to see Nahre on a Physics Girl vid. 😄

[@fairydust..]

The most ambitious crossover

[@jeremybong7238]

Yes! Not complaining tho!

[@bearb1asting]

@@fairydust.. Set it at 30 Hz ^_^

[@mienaikoe]

So awesome to see crossovers happen in the wild!

[@anaghshetty]

haha ikr, as a person who likes both physics and music, this was a present

[@troyhawkins8016]

Great video! I just wanted to clarify that it wasn't resonance that caused the Tacoma Narrows Bridge to collapse, it was aeroelastic flutter. Keep up the great work!

[@guruprasads31]

Hey aerodynamicist here, flutter causes structural failure at resonance. In case of wings it's called the wing torsional divergence speed when the twistey aeroelastic fluttter angle theoretically becomes infinite and the wing fails. Tacoma narrows was a failure due to engineers not considering the divergence speed of wind required to reach resonant frequency on the bridge in the torsional mode

[@guruprasads31]

Also look up the phenomenon called galloping of wires if it piques your interest

[@Igmus]

You used flour for the oobleck? Isn't it supposed to be cornstarch? Flour makes dough or batter consistency. Cornstarch becomes non-newtonian.

[@baqcasanke]

Igmus thats what i was thinking...

[@mikeraines7268]

Caught that also.

[@RobertMilesAI]

The 5hz and 15hz tones probably never even made it into the video, I'd expect the audio compression algorithm to discard anything outside of human hearing range. Edit: Huh, I downloaded the audio and looked at the spectrum, they're totally both in there! That's surprising.

[@AloisMahdal]

Clearly these algorithms are AGI ready. ;-)

[@AFlyingCookieLOL]

The amplitude is low I think.

[@AthAthanasius]

Ah, good, the sign-off catch phrase only had a short vacation :). I definitely remember feeling the chest resonance thing during a nightclub at a Uni way back in the 90s.

[@freetobelee]

You need to be further back for the lower notes. The air pressure needs to build. You have a better chance of resonating your body if you place yourself at different multiples of the wavelength where it is at its peak. You can calculate those physical peak lengths with the speed of sound. PS I studied audio engineering.

[@tadhgsweeney9241]

Also, not so easy to do indoors like this due to room modes and swing, even in spaces large enough to accommodate the wavelength of such frequencies. :P

[@Randommmmm204]

I highly doubt those speakers can do anything below 35hz though. They're PA speakers in a club. I mean come on... Those speakers are just not designed for that. They're made to be loud, not go low.

[@Randommmmm204]

@@tadhgsweeney9241 I'd argue it's easier indoors. My subwoofer is rated for 19hz flat. And outside, it does just that. Down to 19hz, but below that... Nothing. Indoors though, at 12hz EVERYTHING shakes. I can't hear it, but since I can feel it, it's there.

[@JohnSheerin]

You're likely to have better luck by calculating the modes of the room you're in and both standing in an antinode and putting the speakers in another antinode of the frequency you're playing. A good spot for this is usually a corner of the room. You do not need to be farther away to hear lower frequency notes - this is a myth.

[@3yearsago287]

@@Randommmmm204 the speaker in a theater sound way different then a those speakers

[@paradox...]

Playing my 🔥🔥🔥 mixtape through these speakers would light and then put out these candles over and over again indefinitely.

[@chrisjfox8715]

Flames

[@AdamSmith-ow1pj]

The Tacoma narrows bridge collapse was not actually due to resonance but rather aeroelastic flutter. Resonance requires an oscillating driving force, whereas aeroelastic flutter is an oscillation caused by an objects uniform relative velocity with air.

[@rob.chase2244]

The best example of resonance in the diaphragm that I can think of is that boom that you feel when fireworks go off

[@wesleyrm76]

The failure of the Tacoma Narrows Bridge wasn't an example of resonance, but "aeroelastic flutter." Practical Engineering has an excellent video explaining it.

[@ReflectedMiles]

And, unfortunately, both Practical Engineering and Minute Physics didn't know their subject well enough and just replaced one misconception with another. It is common in the real world for flutter and resonance to be related. Musicians are grateful for this. A constant breeze over a reed can produce quite a reaction and result. In the case of the Narrows bridge collapse, aeroelastic flutter excited a torsional resonant mode in the structure of the bridge. You will find this explained by any number of physicists who specialize in that area.

[@jameskennedy7093]

What????!!! Nahre Sol is on Physics Girl!!!!!??? The world just gets better and better.

[@CrankyPantss]

Very interesting stuff. Your enthusiasm always makes the video more fun to watch, too. Happy physicsing, Dianna.

[@RumbleLab]

Thank you for sharing that the part about experiments not working!

[@yunclehead]

There is nothing wrong with an experiment not going as expected because there is still something learned by going through the effort.

[@ZeugmaP]

Collab with Stephen O'Malley ? Anyway it's nice to see Nahre Sol here !

[@SmashedHatProject]

modulating between frequencies has a greater effect on people, including creating excessive nausea.

[@afterglow1478]

Don't know if you're gonna see this, but I went to the dentist a couple of days ago, and whilst they were drilling and prepping the tooth, I think the drill bit my skull's or brain resonant frequency and I felt super trippy and weird whenever the drill hit the right tone. I think it would be super cool to maybe put a transducer against your skull and try to get high on vibrations.

[@biobreak]

used to do sound for bands/theater work and there was at one point where we rented large speakers for a production indoors, the speakers we had "ordered" to be rented were out of stock so they gave us larger ones. this lead to me testing them out in the room we did the production in and i wanted to see what too large of speakers would do. and i ended up actually shaking the room enough to make the lights flicker.. glad no one else was there at that point in time

[@mu11668B]

I'd guess the flame is moving back and forth. Acustic waves can result in pretty large pressure and density perturbation that overwhelms the effect of gravity (buoyancy), thus make the flames seem flattened out.

[@candykanefpv98]

it's displacing air. that's all it is. It's moving enough oxygen away from the candle that it effectively gets snuffed.

[@TildaAzrisk]

@@candykanefpv98 actually I think that its not about the oxygen (it has even more because of the moving air right?) but rather that the moving air both pushes the flame away from the source and mixes it with cool air until the flame is too cool continue burning. But I could be wrong.

[@mrmax35]

As a PhD candidate I really appreciate showing a failed experiment and better yet that you used this failure to learn something! A huge part of real research is learning from failure! Keep up the good work physics girl!!

[@danielbenavente2997]

5:53 Venom, it’s that you?!

[@alexandramootopsyche]

i really like the way you explain how sound changes liquids with resonance. thank you for this video

[@darkxxhimxxlight]

5:38 you mean *cornstarch* and water.

[@RobertRichardsakaRRRRIP]

this is too far down

[@MrMegaPussyPlayer]

4:32 If you want something that makes your body vibrate you'll need a rotary woofer ... frequency range 1- 30hz ... and lots of power in that range as well ... since all it's purpose is to shake the body ... by changing the air pressure in the room ... In the video I once watched (and dunno where it went) they guy experiencing it said, it was like a kick in various body parts ... things I found while I was searching this again: professional solution: www.rotarywoofer.com/ Edit(this line): also relevant www.soundandvision.com/content/eminent-technology-trw-17-rotary-subwoofer some guy DIY ing it ... but not understanding it can't be recorded: kzbin.info/www/bejne/g3ubdah-rqqBqbc

[@AFlyingCookieLOL]

You don't need that when subwoofers, a multiple of them can do the same thing with less distortion.

[@Randommmmm204]

@@AFlyingCookieLOL If all you want is to shake things, you absolutely need that. A regular subwoofer can't go as low as a rotary subwoofer. They might sound way better, but they don't have the same effect.

[@mckenziekeith7434]

@@AFlyingCookieLOL a rotary woofer can raise the static pressure in the room if the room is not too drafty. In other words, the frequency response extends to DC.

[@gigglysamentz2021]

KZbin may also cut out some frequencies from the video.

[@90jcraplee]

I love how excited she gets about physics. Seeing her so amped up for it gets me hype as well

[@IronmanV5]

Am I weird for being disappointed that Dianna didn't play a didgeridoo through the speakers? Maybe next time?🤞

[@AndreLeRoux81]

I'm guessing it's maybe a quirky headset, but I could hear the 5Hz, 15Hz and 20Hz

[@ahmedalshawi8889]

same with me ...i think its not an actual sound wave ...i think it's the driver of the headphone because it's sound like piece of plastic moving in 5clicks per second

[@Tombsar]

5Hz shouldn't sound like a continuous tone because it's way too low-pitched. You could be hearing overtones, or maybe watching the video sped up?

[@FSXgta]

the 5hz you are hearing is mechanical noise, but you can hear 15hz

[@joeshedler6496]

@Physics Girl, thanks so much for introducing me to Sound Field. I really like their channel.

[@tomasthemas]

As someone who went down the bass rabbit hole, good concert speakers can get a little below 20hz but usually not much, because it takes some more engineering to get that low. There do exist dedicated infrasonic subwoofers specifically designed for the sub-bass rumbles! An interesting one that I can't seem to find anymore, was a really small device that used electromagnets to move a weight, that could get down to 5hz if bolted to a floor. You might have to search, but you CAN the frequencies you want!

[@mikerich32]

Dianna, I love your shirt! Where did you get it?

[@i123iu]

Exactly!

[@lariacg]

Try looking for "Cosmic downpour" and please share a link if you get it!

[@NewMessage]

I'm wondering if the song was "Happy Birthday".

[@pvic6959]

when a profile picture has more notifications than you do

[@fustigate314159]

It's now pubic domain because of time (and maybe a lawsuit?).

[@diegogaribay2928]

Are you kidding, you add a nightclub would be amazingly fun! Seriously, this video is really good. Keep on keeping on! Also, where is the audiobook? Your voice is too good. LOL

[@OceanBagel]

I really want to know what happens at the resonant frequency of your ear drum. Would that frequency sound louder?

[@Stevenx01]

"Can you hear that?" * speaks over it * EDIT: * and few seconds later clears that your equipment can't reproduce it * * Ron voice * Damn it, woman!

[@n73n0]

Everything is about vibration/frequency

[@Bustav_]

thanks, i feel very enlighted now.

[@KKing55]

God "Spoke" (Sound) and Created~!!!! satan was the music director of Heaven. That is why he thought he could be GOD~! BE VERY CAREFUL WITH SOUND~!

[@Bustav_]

@@KKing55 are you sure that you are reading the bible? i think that is another book xD

[@KKing55]

@@Bustav_ YES, it is in the BIBLE~ KJV, NAS, Ya have to "Study" the BIBLE~!

[@Bustav_]

@@KKing55 yeah, sure xD because worship isn't sound xD

[@blackmagick77]

This helps a lot. I'm always trying to get a nice bass you can feel in your chest as a sound guy. Now I know specifically where to look.

[@CrazyHorse151]

I think when you manage to create a 3d standing wave with a velocity minimum at some point, you should be able to somewhat cutoff air supply, right? Probably not in practice but in theory?

[@annesmith9642]

Can your eardrums be damaged by sounds you can't hear?

[@ldskjfhslkjdhflkjdhf]

Yes. Especially if they're loud.

[@annesmith9642]

@@ldskjfhslkjdhflkjdhf Scary!

[@ldskjfhslkjdhflkjdhf]

It is scary! Both ultrasound and infrasound can have really damaging effects on your hearing. That's why it's so important to use hearing protection if you know you're going to be working around them.

[@arielapp9469]

Dianna: resonance is the reason why wine glasses break, or why the Takomas narrows bridge collapsed. also Dianna: let's match the resonance of the human body. what could possibly go wrong?

[@jayasrivastava2853]

Thank you for this amazing video *Diana* and *Team* .

[@zakkzahariev4637]

When mixing sounds for film, we often use hidden resonances in the score to foreshadow that something is happening. Often in Thrillers and Horror films, we add 17 Hz to the subwoofer. In certain scenes, this creates a nervous feeling in the viewer (provided they watch the film on a proper sound system) so it can start building suspense. Also, the flames were moving back and forward. Sound is basically a change in air pressure, so it would make much more sense for the flame to move back and forward.

[@jeffreysherman8224]

Dangit, Diana! You used copywritten music?! I wanna hear the sound as I watch the flames move. You shoulda had a KZbinr on set to be like, "Wait. This is going up on KZbin, right? Oh, no, Sweetie. You can't use that music." 😂 They would then hook you up with some royalty free dubstep. 😄 Love ya, Girl! ✌&💗

[@gigglysamentz2021]

Noooo it's not the original music :'( I wanted to see those speakers blasting QuQ

[@olipito]

The only time my chest REALLY resonated, was at a The Prodigy live. Absolutely epic.

[@verebellus]

i have a huge bass that i rested my feet on and when you showed the individual frequenzies, i couldnt hear it, but i could feel it

[@MrBomasBalloons]

I would love to see you look at overtone singing (such as Tuvan throat singing. I can do some overtone singing, and I am in SoCal, like you.

[@andor3xy712]

I really like that you explore sound, I havent seen much from the other physics youtubers exploring sound.

[@MisterItchy]

Standing at the end of the runway in Oman watching a B1-B with full afterburners taking off about 100 feet from me definitely found the resonant frequencies of multiple body parts! Thanks for the video.

[@r08800]

My goodness...innuendo, double entendres and Diana staying perfectly sweet thru it all. Don't ever change Diana.

[@mcbean1]

I don't know if you would call it "hearing" per say by I could definitely detect something when the 5hz was playing and a noticeable difference when it changed to the 15hz was playing through my headphone (Bose quiet comfort)

[@sohopedeco]

In my school, they would let the physics/math competition teams play videogames in the auditorium using their fancy projector a sound equipment. Machine gun sounds in some games kinda made some internal organs resonate.

[@alienmoondudes8071]

with Nahre Soul and I.a Buckner! I love the content they make!!

[@Audio_Simon]

There is a subwoofer used for the purpose of controlled modulation of mountains. This allows snow slides to be managed. I'll see if I can dig up the info.

[@captainastral]

cool- One time I was doing the sound for an outdoor performance, and when I was walking up toward the speaker stack on one side I heard a weird rattle. For a second I thought maybe we had a blown speaker, but listening carefully and moving about the area, I tracked it down- the cross-braces of the scaffolding were resonating because something in the music was just the right frequency to excite them- what a relief; speakers ain't cheap to replace.

[@BrickTsar]

Very cool! It doesn’t surprise me that the music resonates with the trash can so well. Explains how I feel when I’m at the gas station and the guy pulls up that thinks everybody wants to hear his music. I wish for a sound cancelling device

[@Unnassigned]

Yeah that seems to be air vibrating so much back and forth with the speakers (which is moving air?) when the flames goes "flat". Would moving the candles to a further distance change the result? And how far away would the limit be for blowing them out?

[@alexsarullo3753]

Love your videos! I’m going into my first year of mathematical physics, and am so passionate about the field. However, I’m deterred by the lack of work there seems to be. What kind of jobs have you seen physicists occupy?

[@eneurianerwin2287]

i love this video. i studied acoustics under my musicology degree at uni. resonance fascinates me. can't wait for more ''sonic'' videos

[@katiechambers1319]

This was legit on my science test yesterday 😂 we had a whole question about the Tacoma narrows bridge and stuff lol

[@brendarua01]

What amps were you using? What output watt wise and such? This was fun! Thanks!

[@alexlandherr]

Regarding the trials at which you tried making the eye resonate, I recall an interview on the Swedish equivalent of NPR where the case of a researcher in a lab experiencing an effect akin to lightly pressing on the side of the eyeball and seeing shadow-like figures. The probable cause cited was infrasound making the eyeballs vibrate at a low frequency (perhaps resonance).

[@A_Man_In_His_Van]

The low frequency cutoff is the same reason leo fender went from a 15" driver in the 1953 bassman bass guitar amplifier, to 4 10" speakers in the 1954/55 and later versions because the octave lower at 40hz can't be heard, but 80hz that the 10" speaker can reproduce is heard, and it is easier to drive four speakers at a lower impedance with less distortion.

[@sedon7098]

my guess is following the candles were close to the subwoofers and im just going to assume that those subwoofers were ported the air moved by a base reflex port very directional and the candle blow out trick is pretty easy to do if you just place the candle right. If you want to check out some really really interesting stuff with speakers you might want to take a look at horns and their insanly high efficiency. I know a bit about that stuff so if you want to know more just message me (that goes for everyone btw) and i would be thirlled to discuss some speaker stuff and might even get some more insight myself

[@alfiangunawan5946]

i thought the flame shakes because of the pressure from the sound wave

[@PhattyMo]

3:47 -Beyond that,it's also a matter of the codec(s) KZbin uses for audio compression. Low freqs. tend to sound 'crunchy' and distorted with KZbin,IME. I'm not sure what the cut-off point is(probably depends on quality setting),but at some low freq,you probably aren't gonna hear anything,regardless. Also,low frequency equals long wavelengths,try standing against the back wall of the club,and see if it's any better/different.

[@MyrkDomolith]

On decent and decently cheep over-the-ear headphones, Sades SA-680's for those willing to test, I could hear the 5 and 15-hz notes I couldn't hear them directly/as notes. I could hear their effect on the ambient noise being played through the videos. It's like listening to one frequency in one ear, and another very similar frequency in another, but only getting the amplitude decrease from the resulting beat frequency. I only noticed I could hear it because it affected PG's voice during the 15hz part. It sounded like she was talking from behind a running fan, except the fan and the wind it generated were silent. Double checked the 5hz part and I heard it there as well. Both were faster than I thought they'd be. Soo... If it's not just me that can hear that, then I guess speakers CAN play those frequencies, but anything below their lower limits would have to be piggybacked on to higher notes, and it'd be heard as a beat frequency.

[@a.i.9560]

I remember in 1979 doing Full engine run test on a KC135 (4-J57 jet engines) when they did the water injection test a full throttle, it took ALL my wits not to run away. I always thought it was the Volume but I wonder if Resonance could have been at play also.

[@dscrive]

I heard your reference to "The Sound of Music" I foresee a collaboration between Physics Girl and Cody'slab to make the hills literally come alive with the sound of music. . .and dynomite.

[@sparkyprojects]

The db rating is the SPL (sound pressure level), so it's a pressure wave that resonates objects, just like a large explosion will have a pressure wave radiating out. Don't forget the 'brown note' or Brownian motion. ;)

[@gibbytravis]

You can hear 15 Hz if it's loud enough. When Fletcher and Munson did their experiments in 1933 to map the sensitivity of the human ear, the curves that they mapped didn't suddenly roll off at 20 Hz, like a brick wall filter. Rather the sensitivity of the ear rolls off very sharply below about 100 Hz and the steepness of the curve increases as the frequency decreases. I personally have heard sine waves below 17 Hz from my own DIY sub.

[@charles_wipman]

Nice!, i love that feeling on my chest and i'd enjoyed it a lot when many years ago Jello Biafra & The Guantanamo School Of Medicine came to my town; i bet the 1st Body Count LP will make me feel really good with those speakers. Enjoy the rest of the week!

[@Aengus42]

I seem to remember reading in Lyall Watson's "Supernature" of experiments with I giant, concrete french police whistle driven with compressed air used as a weapon (focused infrasound). Add to that an ex British army vehicle at the last Stonehenge free festival in '84 that came with huge bass horns that was VERY uncomfortable below audible frequencies...

[@drphu]

I got 132 DBa in my car with 100W stereo and was way back in the day early 80's these days the sound is mostly cruddy in car stereo since the sound is not flat and the source audio has no depth.

[@rogergadley9965]

Great video. You may know (or may not know) that modern war battlefield sounds sometimes cause vibrations which seem to be resonant with our body. I’m thinking specifically of the 20 mm Vulcan Gatling guns mounted on the F-4 Phantom in Vietnam. I was under (on the ground) as an F-4 flew over, shooting at the ground ahead of us. The sound was so loud and the vibration so fierce that our insides felt like they were turning to mush.

[@seanehle8323]

If your precision on the eyeball shaking resonance was as wide as 2 Hz steps, then it's not surprising you didn't feel it. In the resonance demonstration I use in class (a mass on a spring connected via spring to a driver), the resonance response is sensitive to within a couple tenths of a Hz. IDK if this would make the difference to feel it, honestly, but I have reason to suspect that the resonance frequency is more sensitive than a 2 Hz jump could "tune in."

[@MidwestArtMan]

When you said, "There's a 5 hz tone playing under this video right now," was there supposed to be silence after it? I heard what sounded like a slight high-pitched audio flutter when I put headphones on and it sped up at the 15 and 20 hz parts. 65 hz sounded like a single tone, though. When I sped it up to 2x speed, the 15 and 20 hz sounded like consistent tones, too, even though the frequency shouldn't have been affected. I'm guessing it's my headphones being weird? I could also hear them try a few different frequencies for the eyeball thing.

[@danielmount6928]

The speakers are pushing out wind or air as well as sound. That is why the flame was moving and as you push it up the win gets stronger thus blowing out the flame.

[@keatonjones6115]

I can confirm the phenomena of the resonant frequency within eyeballs but the volume has to be incredible, I used to install competition grade stereos in cars, it took 4x 15 inch subs in a little hatchback each 2000 watt rms (not including speaker). We played the low notes and 15-22 hertz would make our eyeballs shake, teeth chatter and oesophagus vibrate so immensely it was impossible to stay in the car for more than a minute or 2, even our lungs fealt like they had taken a beating/shaking. To truly feel the phenomena the military paper describes go to a car audio competition, you not only need massive wattage, but you need it in a small place for those pressure waves to build up/resonate within the car and everything in it.

[@lustig8312]

Some home theater folks have built "rotary woofers" that can reportedly produce frequencies below 20Hz. It's like a propeller whose pitch is varied by the audio signal. I've never experienced it but I always thought it was a cool idea. Some of the home theater subwoofers are crazy too. If you play a sine sweep you can hear various objects in the room start to rumble as it sweeps through the frequency range.

[@johnmichaels2495]

An interesting phenomenon to discuss is that of Schumann resonances, something that mostly occurs at ELF frequencies with electromagnetic waves. Amateur Radio operators will be familiar with radio wave propagation, where radio waves (especially in the HF bands) are reflected by the Earth's ionosphere, allowing long distance communications. At certain ELF frequencies this space between the earth and the ionosphere acts as a waveguide and it is possible to create a standing wave all the way around the earth. Also, as a side note, audio, especially high power audio, is an extremely difficult engineering challenge because 20kHz is 3 orders of magnitude above 20Hz. Designing a single speaker driver that can do this at high power with low distortion is nearly impossible. This is why you often see

[@erictaylor5462]

1:30 There is (or was) a way to put out an oil well fire that involves setting off an explosion close to the fire. The explosion set off a shock wave that plows the flame out. All sound it is a low amplitude shock wave. I know that the first Golf War radically changed how we fight oil well fires. We learned a lot about putting them out quickly because Sadam started so many.

[@R4MP4G3RXD]

For extremely low frequencies with a high output you should use/find some rotary woofers. They're very hard to make, noisy and also very hard to properly implement, so they're a challenge to find, but those could potentially work for making your eyes resonate.

[@brianlewis8060]

I have some Cervin Vegas that will lay them candles flat, but that's because it also has ports to let the air out do to the bass 🔊 compression, I'm glad you love some beats, stay safe!!!!!

[@jamesroseii]

Years ago, I had a job in a plant that makes oil seals. One night, bored, I began to hum along with a machine that was running behind me. I didn't think anything about it but I noticed that when I matched frequencies with it, it would make my skull resonate. It felt good and weird and I was contemplating the existence of "nothing" (I'm weird, I know) and this skull resonance actually pushed me over into some religious experience where I got to see "nonexistence" and it made me feel "high" for 3 days. It was all super-trippy. I tried to tell people about it and everyone thought I was on drugs. Finally, I told a friend about it that had studied Buddhism and he told me that I basically inadvertently stumbled upon a Buddhist mantra (humming and meditating on "nothingness") and had a breakthrough. It was such an amazing experience.

[@Godlobber]

After being in and around music for 35 years and having studio quality headphones on while watching the video I could hear/feel the 15hz frequency, pretty cool sensation.