Debunking Audio "Truths" - Open Baffle Speakers don't Pressurize The Room
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- Опубліковано 23 жов 2023
- Sound, the final frontier. These are the voyages of the shit disturber John on his 5 year mission to seek out the nonsense and to boldly go where no audiophile has gone before.
Sound is energy that travels through a medium. For most purposes, air is that medium, so we need to understand how sound behaves in it.
Sound waves are so-called pressure waves that have a high pressure peak and a low pressure trough. That peak to peak amplitude is the strength of the energy of the wave. A larger peak to peak value will be louder.
As sound energy moves through air, it form a region of high pressure that's immediately followed by a region of low pressure. The air in the space is being energized by that sound energy - in other words (and perhaps wrongly), it's being "pressurized".
But it's SOUND pressure, not air pressure.
When you hear the word "pressurize", you probably think of blowing up a balloon, but sound doesn't work that way. The high / low pressure nature of sound energy means that there is no net change in the air pressure of the room the sound is playing in.
So there will be no rushing out of air when you open the door of a "pressurized" room that's being "pressurized" by sound.
The sound energy is, as I described in the video, making the air molecules vibrate more (and less) than they normally would, very much like a big block of jiggling jello.
Now this only happens (this pressurization idea) below what's known as the Schroder frequency. That's the dividing line between sound behaving like rays and sound behaving like pressure.
When low frequency sound is being put out by a speaker, it will energize the air, regardless of what type of speaker is making the energy. In other words, 40Hz at 90db is still 40Hz at 90db whether it comes from a sealed, ported or open baffle speaker. Sound energy is sound energy, no matter where it comes from.
So saying an open baffle speaker won't pressurize a room is simply not true.
Ergo, saying that open baffle speakers don't excite room modes is ALSO not true, since room modes are excited by the SOUND ENERGY a speaker produces, not the speaker itself.
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Sound, the final frontier. These are the voyages of the shit disturber John on his 5 year mission to seek out the nonsense and to boldly go where no audiophile has gone before.
Sound is energy that travels through a medium. For most purposes, air is that medium, so we need to understand how sound behaves in it.
Sound waves are so-called pressure waves that have a high pressure peak and a low pressure trough. That peak to peak amplitude is the strength of the energy of the wave. A larger peak to peak value will be louder.
As sound energy moves through air, it form a region of high pressure that's immediately followed by a region of low pressure. The air in the space is being energized by that sound energy - in other words (and perhaps wrongly), it's being "pressurized".
But it's SOUND pressure, not air pressure.
When you hear the word "pressurize", you probably think of blowing up a balloon, but sound doesn't work that way. The high / low pressure nature of sound energy means that there is no net change in the air pressure of the room the sound is playing in.
So there will be no rushing out of air when you open the door of a "pressurized" room that's being "pressurized" by sound.
The sound energy is, as I described in the video, making the air molecules vibrate more (and less) than they normally would, very much like a big block of jiggling jello.
Now this only happens (this pressurization idea) below what's known as the Schroder frequency. That's the dividing line between sound behaving like rays and sound behaving like pressure.
When low frequency sound is being put out by a speaker, it will energize the air, regardless of what type of speaker is making the energy. In other words, 40Hz at 90db is still 40Hz at 90db whether it comes from a sealed, ported or open baffle speaker. Sound energy is sound energy, no matter where it comes from.
So saying an open baffle speaker won't pressurize a room is simply not true.
Ergo, saying that open baffle speakers don't excite room modes is ALSO not true, since room modes are excited by the SOUND ENERGY a speaker produces, not the speaker itself.
"Ergo, saying that open baffle speakers don't excite room modes is ALSO not true, since room modes are excited by the SOUND ENERGY a speaker produces, not the speaker itself."
Nobody says that open baffle speakers don't excite room nodes. They do however say that open baffle speakers excite room nodes differently. As we all know, off to the sides is huge cancellation, especially in lower frequencies. Thus they minimize the effects of bass nodes due to the side walls.
If there is a difference, that difference would happen because there is less energy output overall at the frequency. So the side cancelation just reduces the energy output in total, and not because it's doing it in that specific way.
And yes, plenty of people think open baffle speakers don't excite room modes.
@IBuildIt You are wrong on both counts. Are you sure you build speakers? Asking as you seem to be unaware of the figure 8 output of open baffles and planers, and how they propagate sound. They sound smoother due to how they load the room, not due to a lower total output. As far as audiophile beliefs, I've yet to hear one say they don't excite room nodes. With an 8 foot ceiling, there will be bass nodes at 60 and 30 Hz to contend with, regardless of speaker type.
You are falling into the same trap as most other do when thinking about how sound propagates in an enclosed space. Bass frequencies are said to act as pressure because they overwhelm the capacity of the air in the room to contain them, so instead of behaving like a ray (like higher frequencies), they more or less just slosh around the room. They FILL the room.
The bass energy from a dipole has a cancellation at the side, but you'll only see that when you measure close to the speaker. Farther out, the bass appears as omnidirectional, just like any other speaker type.
I not only make speakers, I also measure them and I measure what they are doing in the room. I know from real-world, first-hand experience that the only way to reduce how much a room mode is being excited is to produce less bass at that frequency. What you (and others believe) is not possible in a small room.
Big rooms are different, since they can contain the bass energy without it building up. But big rooms are BIG - gym size or church, not a room in any normal house.
What we hear are wavefronts: pressure variations occuring at our ears when the wavefront passes by. Under the Schroeder frequency the dipole speaker will fill the room with opposite pressures that will cancel out. Therefore not pressurize the room while still energizing wavefronts that will be heard, just like frequencies above. Not so with a monopole speaker. You can actually feel the rush of air through the port that comes to pressurize the room, before receding back in the box. We get room gain, especially useful in very small spaces. There's probably less room gain with dipoles, but still some because of boundary effects to the wavefronts.
Because an open baffle speaker radiates a dipole pattern, with cancelation happening left, right, above and below it, there is far less energy coupled into the room as a whole. That focused bass, has a different feel. It's great as you are not pumping energy into the floor and ceiling and side walls that will propagate into adjacent rooms. So that's good for multi-floor multi family buildings as you are only exciting two of the six surfaces in the "cube" listening room. The only way to produce high fidelity bass is a sealed woofer or open baffle. The other schemes add delay and resonances to plump up the sound at the expense of accurate transient response and additional group delay.
Great job by provideing an intuitive explanation describing compression and rarefraction of the fluid by sound waves. Your explanation succinctly covers sound propagation in water and solids. When using a screw driver to listen to an engine knock, sound travels in a solid and the pressure does not increase in the metal. However, compressive and rarefraction waves follow your great explanation. Keep up the good work and sharing your understanding and applied research.
In a closed box speaker the compression wave from the front of the driver is not cancelled by the rarefaction at the rear of the driver as it is with a dipole. The cancellation nulls produced by a proper small baffle dipole make it directional all the way down into the bass region. When pointed at the listener, it therefore puts only a third of the energy to the room as it does to the listener, as does a cardioid with the only difference being that the null is in the rear with a cardioid and not the sides as with a dipole. This is easily seen in polar measurements...measure your dipole at 90 degrees off axis and compare it to a sealed box at 90 degrees off axis and it's obvious; a dipole is a velocity source and a sealed box is a pressure source.
If you play 40hz through a sealed box and a dipole in the same room, with the same sound pressure level at the listening position, if that level is sufficient to stimulate your pressure receptors (mechanoreceptors) you will easily feel the difference.
A ported box unloads below the tuning frequency and begins to cancel rolling off at a very steep slope, thus the use of rumble filters to protect the driver unless it is a sufficiently large subwoofer tuned to a very low frequency.
As Linkwitz stated, a dipole means more energy for you and less for your neighbors. I've been building dipoles for over 2 decades and I use a sealed sub below 60hz, where music is mainly felt through mechanoreceptors. Of course the kind of music you listen to matters with regard to how much pressure is in the recording, as some bass instruments are pressure sources and others are velocity sources. You appear to only be considering the compression and rarefaction from the front wave of the driver and ignoring their out of phase opposites from the rear of the driver. Cheers to frontiers and all the best, Jason
*THE SEA* does not pressurise a ship - but it sure moves it up and down...
The effect of the air's humidity is also something to consider.
I did the sums. When a closed box bass driver moves forward it DOES reduce the room volume, which DOES increase SPL in a fully sealed concrete room, but how much? Well, for a typical listening room size and a 12" bass driver moving 1 inch forward (and staying there), the pressure increase is....wait for it.... 0.0002 dB. Much less in a room that leaks or has non-rigid surfaces. Add in the realities that bass frequency hearing is summed and delayed, not instantaneous, and one can conclude with great confidence that there is nothing audible going on whatsoever.
I have a small ONN speaker in my two car garage woodshop. The walls are unfinished, but when I put in earplugs, the low sound is much more intense.
John, there isn't a physicist out there that has a grasp of the fluid dynamics of sound, that can explain it in laymen's terms like you do. Thanks!
Yes it is a strange phrase. If the speaker creates velocity there will also be preasure, the two components of a sound wave.
It is true that open baffles are less able to produce sound at low frequencies though, which is why they need a good dose of EQ and lots of active surface area compared to a mono-pole.
I think they mean average excitation since normal speakers with a closed box produce an average room pressure difference. When gone goes out pressure increases. In a open baffle the average is always zero since you at the same time have a negative pressure behind the driver so sum is always 0 since there is no box to contain the rear wave.
No, they are all the same as far as the pressure produced is concerned. Think about it: as the cone in the sealed box pushes forward, what happens next? it pulls in, of course. Equal - no change.
Same thing happens with the dipole, but on the front and the back - no net increase in air pressure from either.
Even an infinite baffle sub won't create a net increase in pressure, even though the back-wave of the speaker is happening in another room entirely.
@@IBuildIt The point is, if you take a snapshot in time rather than the average. You talk in your video about average pressure over time, the commenter above was referring to average pressure at a snapshot in time depending on where the cone is in it's cycle. When the cone of a sealed driver is extended outwards, at that instant, the volume of the room is now smaller, which means the average pressure of the room must be higher (PV=nRT). An instant later when the cone is retracted, the volume of the room has now increased and average pressure in the room is lower. An open baffle would not have this same effect, as the volume of the room is constant. How that difference affects sound is beyond me, but the statement that a sealed driver affects average pressure in the room is absolutely true, at least when comparing pressure at snapshots in time. Your explanation that over even very small time intervals the average pressure of the room doesn't change is also true, I think you might just have missed the core of the myth you were trying to debunk?
Thanks for sharing.
thank you
Good basic explanation John. Now let's see that jello move again...😂😂
So… front port and rear port doesn’t really make a diff, correct? (In regards to air from port interfering with sound)
I remember reading many saying/thinking the air from the front port on say KRK monitors interfere with the sound. (As opposed to a rear port, like Yamaha HS)
i know people do not mean the same thing or understand the words the same way.
but i generalized the saying this way: an open baffle speaker sounds like it doe not pressurize the room since the lowest bass is rolled off.
25hz and below it feels more like a air pressure, and between 25 and 200 it feels like a body punch, wich open baffle can reproduce.
hope that clarifies something.....
Everything your speaker puts out is a wave. Sound is what you hear. Your ear drum moves as a result of the pressure waves and sends a signal to your brain which it interprets as sound. Sound only exists in the mind.
It might be interesting to compare a sound wave moving through a space with very high air pressure and very low air pressure and see if there is a measurable difference between that and moving through "normal" air pressure space. Maybe somebody has already done this experiment. But I'm all for tangible emperical evidence. Thanks for actually thinking through these issues and testing them to see if "conventional wisdom" is actually accurate or not.
The speed of sound changes with altitude and that happens because the air pressure is lower at higher altitudes. Lower pressure equals thinner air.
But sound will still behave the same way in a room with lower air pressure.
Man, I love this guy’s videos.
Do you have a video on the speaker pictured in the thumbnail? It looks interesting.
Upcoming project, still not fully designed.
LOL. “Pressurize the room”
I haven’t watched yet, but yes, speakers move air far slower than supersonic.
I think a lot of people have a hard time visualizing a sound wave. We always see graphs (or even cheesey graphics on promotional materials) that explain a sound wave's frequency and amplitude in two dimensions. This looks like a wave on the surface of water, viewed from the side.
In reality, sound waves are three dimensional pressure fronts, smoothly transitioning from high to low and expanding outward in all directions from the source.
The way I visualize this is like a giant, invisible onion, continuously expanding in all directions from the speaker. Each ring represents the alternating high and low fronts.
When we talk about the length or hight of a wave, people I think tend to visualize this 2D wave bouncing up and down. Which of course is wrong. Going back to the invisible onion, the onion is expanding at a constant rate, the speed of sound. Which I believe is something like 1130 feet per second? So the length of the wave is the distance that wave expands in all directions during the duration of one cycle, high to low and back to high. At 20hz, the wave expands 56.5 feet in the time it takes the woofer to travel from it's high peak, the low peak and back to high, one time.
Amplitude has nothing to do with the size of the wave, but it's the contrast from the lowest to highest pressure that will be experienced in the air.
If you have a normal size room, it won't be 56 feet in any direction. So that low to high gradient won't even pass by your head unmolested. The high peak will pass your head, bounce off a wall and come back, albiet at ruduced amplitude. But it's still there. So that raise in pressure will polute and hold up the falling trail and you won't experience the true low peak. Same for the low peaks interfering with the high peaks.
The onion is a good analogy.
You did say something that is incorrect, but maybe it was a typo - you said that amplitude has nothing to do with the size of the wave, which is obviously not true. Maybe you meant to say it has nothing to do with the LENGTH of the wave, which is correct.
Sound is almost too complex for most people to get their heads around, especially if they are operating on basic ideas presented in a simple way. The low frequency sound sloshing around a room is insanely complex and it's happening in 4D, with time being the one factor that's most elusive for most people.
@@IBuildIt Thank you. And yes, I suppose length would be more accurate. I don't know that the wave will be shaped any different at higher or lower amplitude, within the confines of a room? Obviously, it will propagate further. But it's an important distinction to understand amplitude as a contrast in pressure, not a physical dimension. Least of all, length. 2D graphs show amplitude as height, which doesn't translate into real life.
Why does everyone make this so complicated? Its easy. Really.
A room is a box filled with jiggling air molecules. The amount they jiggle depends on the temperature they are at and the amount of pressure they are experiencing around them (atmospheric pressure).
A loudspeaker wether the cone is pushing or sucking will always deposite a little residual energy in room, which is heat. If the room has leaky doors and windows, with thermally transparent walls, the extra heat energy will leak at the same rate as the cone vibrates. The net result is no long term change in pressure.
There have to be momentary changes in pressure otherwise we wouldn't hear anything.
They key thing is the room is an open system so over time the excesses energy from heating the air molecules through vibration is almost instantly dispersed outside the room.
However, if a small speaker were placed in a closed system - a perfectly sealed and insulated box - then there would be rise in pressure as the air molecules warmed. Eventually the cone would become harder and harder to move. However, in the real world this doesn't happen.
If one then considers a large, crowned and poorly ventilated night club or concert hall then the quality of sound transmission is noticeably different as the temperature and humidity rises. This is due to the warming and moistening of the air reducing its density and transmission properties.
The effect is certainly noticeable at a certain famous concert venue in London on hot humid evenings. The sound changes as the sweat and heat from the large audience rises.
At about 6:48 you state, 'peak being positive Pressure and trough being negative pressure'. You are conflating a sinusoidal function, with Compression and Rarefaction. Compression, the Density of the medium is greater and in Rarefaction the Density is less, but at no Time is there, "Negative", Pressure.
In Labs I've worked in, were plating contagious/dangerous organisms is performed, plating said organisms on a growth medium, AKA petri dish, there is negative Pressure. As air from the room is pulled out of the room and into the Hood, the workspace, and then through a pipe containing a series filters, before being exhausted into the Atmosphere.
I'm not conflating anything. If you look at the net air pressure in a room, it's a relative constant. Call it the the baseline. When sound is created, the "wave" produces a pressure above the baseline and below the baseline - Plus and minus.
In the video I included a simple example of exactly that, when a rock is dropped in water. And you can see that happening in that example.
I reject the terms "compression" and "rarefaction" to describe sound energy, because they are misleading as well. In particular compression - how much compression actually takes place when sound goes through a medium like steel, do you suppose?
@@IBuildIt Well you are free to reject anything you choose, but to describe the propagation of sound in a dispersive absorptive medium, air, the terms are derived from the Discipline of Physics.
The velocity of a sound wave is affected by two properties of matter: the elastic properties and density. So you doubt that the crystal lattice of a metal is behaving at the molecular level, as a gas or Liquid, in the Classical sense, because you cannot perceive the displacement at the crystal lattice level? I suggest you research normal modes of vibration in a solid and perhaps then move onto the definition of Phonon.
Think about what you are arguing. I say I reject the term "compression" and prefer to use the term "pressure amplitude".
Tell me, when sound is happening in a tuning fork, what would be the best way to describe what's happening? Would one say that it's compressing and rarefying, or would one say it's vibrating?
And when describing a vibration, wouldn't it be natural to use the term amplitude to talk about the strength of the vibration?
Sound makes stuff vibrate - the air, water, metal, etc.
When it does that, it's dumping energy into the medium and that dissipates in the form of heat.
What happens when a medium heats up? It expands, of course, so using a term like "compression" is confusing and counterintuitive.
@@IBuildIt
Well, you are now altering the discussion away from positive pressure and negative pressure, which was what I originally posted about, and wasn't correct in terms of the transmission of energy via the dispersive absorptive medium, in our case, air, defined as sound, We were first discussing. Now, you transition, to support what you believe should be the best way to describe the actual phenomenon, by discussing sound moving through a solid.
I briefly scanned and found this definition.
"In solids, waves propagate as two different types. A longitudinal wave is associated with compression and decompression in the direction of travel, and is the same process in gases and liquids, with an analogous compression-type wave in solids. Only compression waves are supported in gases and liquids. An additional type of wave, the transverse wave, also called a shear wave, occurs only in solids because only solids support elastic deformations. It is due to elastic deformation of the medium perpendicular to the direction of wave travel; the direction of shear-deformation is called the "polarization" of this type of wave."
Will you agree that the term decompression equates to rarefaction?
This seems to be what you are objecting to in the first sentence, compression, in a solid which does occur at the atomic/molecular level, known as the crystal lattice. And is the mechanism for energy transfer. "Heat is the process of energy transfer from one physical system to another."
"Sound makes stuff vibrate - the air, water, metal, etc." From definition, "Sound IS a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid."
Again I employ definitions and not interject my personal opinions. Sound makes stuff vibrate, or Sound is a vibration. That is the quandary.
I won't deny it may seem counterintuitive, but that's the way the Universe works and if it disturbs you, it was told to me by a Prof, that is the first step in the learning process. I'm not trying to be a PITA, just that your terminology and possibly understanding doesn't align with a few hundred years of Physics paradigm. It not a big deal, its your channel and I enjoy your empiricism. So, I thought I would add my two cents to illustrate what is actually occurring. Your, "So using a term like "compression" is confusing and counterintuitive." Well, yes, I agree it is, so I copied two quotes about what Bohr thought concerning His own work discovering How the Universe actually operates.
" Those who are not shocked when they first come across quantum theory cannot possibly have understood it." " If you are not completely confused by quantum mechanics, you do not understand it."
Take care and thanks for your Time.
Guy, I'm approaching the phenomenon from different angles to try to get you to understand what it is I'm saying. I'm not changing anything I've said, but dumbing it down to get through to you.
What's another way to say compression and rarefication? High and low pressure.
Your obstinance at this point is bordering on ridiculous, so let's agree to disagree.
Pressurize the room? OMG. I wish "audiofiles" would refrain from talking physics unless they have a physics degree.
I think the phrase “pressurize the room” came from home theater types and not audiophile types. Either way, the term was not meant to express physics concepts. It was a description of how powerful subs feel to one’s eardrums.
😆
If there was no pressure, there would be no sound!
If there is no listening, there will be no understanding!
😆
Excellent analogy. As an engineer I relate to this.
Nothing debunked and only potato/poteto about what we define pressure as. And even when pressure is wrongly referred to most of us probably know what they try to express. 😂
Test setup:
1. I have first hand experience with two OB 18" woofers hanging in the air from the floor boundary.
2. REW and calibrated measurement microphone.
3. A miniDSP.
4. I love equal loudness curves as implemented perfectly and verified by REW.
So I have difrent equal loudness curves depending on listening levels and how a album is mastered.
Defined as presets on the miniDSP remote.
As we know the equal loudness is very "smiley" for the lower listening levels.
In short there is a 50 dB gain at the most. At 20 Hz and down to 1000 Hz.
There is no non linjerity in the graphs it is perfectly PEQ and the graphs ls looking as the equal loudness graphs in Wikipedia.
Of course I have 8 big and very thick absorbers with 6 diffusers as I try treat the room first in the physical domain before I start with PEQ.
So with All that background said you now should know that I am playing VERIFIED lower than 20 Hz and at very elivated levels in the bass region..
It took me over a half year to wrap my head around when I knew that I play low and with higher loudness.. And I could hear everything clear and detailed.
But there were no bass visceral or chest pounding feeling. Nothing is shaking or vibrating in the house and the pants legs is not vibrating!
It is the furthest from a home theater bass that you want and the closest to hifi when you can hear everything.
Took me a very long time to get used to that bass presentation. First I didn't believed or understand WHY I don't get that bass physicall feeling.
We are all so used to the presentation from boxes so it takes a long time to get detoxed from that. But it is OK when you can hear every details and you re-enjoy your favorite albums again and hear new things in those recordings.
But yes boxes are more fun in the short run and more effect full best for HT but OB is best for hifi critical listening.
So in short OB bass don't make the "jello" (new and corrected nomaclature when pressure is wrong as said in the video) vibrate so that you feel it in your chest.
(irony) 😅
So with all those declared preconditios above in the test setup.
I can with very high likelihood say that OB jelly shaking is low compared to a box and nothing were in the testing "debunked" when it is confirmed that it is so. ❤🎉
And as usual "hearing (and fealing) is believing". So have you not lived with that extreme setup and experienced it I understand that you don't buy into it.. When I am also the same that I need to experience it first hand to REALLY believe it.. 😢
There is fundamental wrong statement in the last sentences in the first pined post.
That the effect of a woofer is the same independent if it is in a OB or a box..
Well a box is omni directional but a OB will cancel.(cancelation) the bass radiation to the sides, up and down (mine is in the air) for the number 8 dipol pattern.
Therefore also not inpact and couse bass issues when it is loading the room far less than a box does. 😮
Thank you for clarifying this. I like this kind of video. This is also how I understood it (pressurizing) from some other academic's presentations.
I don't have a lot of experience with open baffle but I see a lot of bigger drivers to get more output. I also read the qts should be around 70 to a 100
I can only see trying to find a rap song where John is using his hands to talk and the outfit looks so gangster hood! 😅🤣😂
I do remember sometime ago...when I was a pediatric patient...when my mom came in the room when they were taking my pressure....my pressure raised a good 10 points... I'm gonna have to watch this again now....
Hello folks: I feel why lack of low bass in open baffle. The box become the drum skin driver is the drum stick. That's what missing or weaker. A 15" open is like 10" box. As the box driver focus the blast of energy out as a sunflare in a beam.
Open this energy is 360 spread around out or 16x4" drivers box this reinforce to lower the FS of a single driver.
Yep I'm still crazy
Ride Easy
I'm wondering if I place a woofer inside a kick drum. What the outcome is?
How do you think. Not what you think you know. Nice post poster.
I am building duo 2in 4 ohm summed to 8 ohm, open baffle at ear level, from 700hz to 5khz. the front mounted ribbon takes 5khz up. A single 8in carbon fiber right below700 hz to 70hz , a 3 way. High pass fmod to mono block amps. Subs are plate controlled (500watt dayton) I blend with douk preamp to hipass/ subs are duodayton18s all sealed . This eliminate the pressure probem of large open baffle bass. I have to adjust the system a little depending on music listeners taste in music and the era of the recording. It gets a little technical.
I use spotify eq and correct the OB peak at 1khz or 2khz neg a db or so. And watch people (experts)
Roll there eyes in disbelief. One even cried. I have built over 500 systems in auto and clubs an churches an home concert
Good description: I am subscripting,thanks
1:41 what? “Pressing down” please check the second law of thermodynamics, as that statement is total nonsense. Gasses do not go ‘’down”! Gas expands in all directions and presses in all directions equally on the walls of the container. Gas has no bias down, on the contrary, gasses are produced at ground level and make their way *up* as they expand in line with entropic law (the second law of thermodynamics).
Gas does not have weight. The ocean is not gas, gas does not behave like water, they are totally different states.
“I think one of the confusions is” people conflate water (bonded) with gas which has no bonds when detailing “weight” a measure of solid and liquid *in air* again, air has no weight. If you think it does, please let us know what the weight of a gas molecule going *up* has?!
“Light rays” bouncing off widows…. Nope, “light rays” are a computer concept and do not exist in reality, feel free to show us one.
This whole video is a masterpiece of convoluted nonsensical pseudoscience.
Seriously, your videos are usually so good, why babble nonsense? 4:44
Gas going up (as in a balloon) has positive buoyancy. It is lighter than the surrounding gas. Of course gas has weight. Everything that has mass has weight. F=ma ==> F=mg.
Air pressure, commonly called atmospheric pressure or barometric pressure , as John described is absolutely due to the weight of the gases in the air 'pressing down' due to gravity. Fluid pressure in either open or closed conditions is observed in all fluids which include both gases and liquids, therefore it is absolutely appropriate to think about atmospheric pressure in the same was as the pressure under the ocean. The only difference is that being under a column of air you are going to experience a lot less pressure (force) than if you are under a column of water. Why is that? Because the water is far more dense, in other words it has greater mass for the same volume.
Within a closed container pressure can be described as 'molecules bouncing off the wall' and yes it appears we can increase that pressure. With a balloon we are either trying to increase the pressure by blowing in a lot more gas than the volume of the deflated container, in which case the container will try to expand to equalise with the surrounding air pressure. Or we might be heating up the gas in the balloon to excite the molecules so they do hit more against the walls and expand them. The reason the hot air balloon rises is because the same mass of air has been excited sufficiently to expand the volume of the container. Therefore the contents is now less dense than air and it floats. A kids balloon inflated with normal air does not float because it expands to achieve the same density as the surrounding atmosphere.
However, again as mentioned by John, with sound we are pushing the air backwards and forwards, we are not exciting it enough to change the overall pressure of the room. Certainly not with the sort of volumes speakers could produce. The only very slight chance of a pressure increase is dissipation of sound energy to heat, an increase in room temperature will increase pressure in the room (like the hot air balloon). But again with the amount of sound energy and room volume we are talking an imperceptible temperature increase and therefore similar lack of pressure increase.
You're about to have a hard time explaining how bodies form in space, how an atmosphere can exist and so on...
You're forgetting Brownian motion.
“Speakers pressurizing a room” isn’t a phrase that makes any sense. To build on John’s explanation, sound is a minor perturbation in pressure that has to travel from the thing that’s causing the perturbation because the medium (air) acts to restore equilibrium. This moving pressure perturbation is something that exists superimposed on the *bias* that is the air pressure itself. Sound waves follow the same behavior as other wave phenomena: reflection, diffraction, absorption. For bass frequencies, diffraction becomes the predominant mechanism in a typical room because the wavelengths become roughly the same size or larger than the objects in the room or even the room itself.
Speakers pressurizing a room is a thing, just not a most common frequencies, below 20hz and certainly below 15hz it literally feels like pressure, ears hears nothing at that point. so there you go, now you know, and how you experience it one day.
@@sudd3660 It may "feel like" pressure at 20Hz and below but it's still just sound being sound - no different than 200Hz or 2000Hz. All that's different is your ability to perceive - becomes more skin (to include body hair), less ears.
@@hubbsllc i am telling you, you have to experience it to talk about it, a pressure sensation is the feeling. so that is valid enough to use the term in that sense.
@@sudd3660 I'm a bassist and keyboardist whose idea of a good time is the original Moog Taurus pedals - I'm quite familiar with the experience. Nevertheless, "pressurizing a room" with speakers isn't a sensible statement.
@@hubbsllc
it is descriptive, that is what i am trying to say.
and still i think you have never had the experience otherwise you would have know how accurate that pressure description is.
dude reminds me of the great lebowski
Sound is not the movement (permanent dislocation) of the medium, it´s only back-and-forth vibration in the medium.