Well, a search for "youtube acoustic fire extinguisher" indicates it has already been invented a few times by people all over the world. The most interesting video is https://www.youtube.com/watch?v=ZvnCQg4w4o8
Was looking for a video on this specific work, but only found this [1] where the English translation seems AI-generated. It reminded me of thermoacoustic refrigeration which I found cool (heh) when I had encountered it many years ago - where the compression and rarefaction of sound waves is used to pull out heat. The fire extinguisher seems to operate on a different principle though - it needs to generate a specific kind of turbulence to push out oxygen from the fire site.
It's kinda a throw-away remark in the middle, but I thought it was really cool to realize that speakers produce an on-axis net-blow and an off-axis net-suck.
This channel (The Action Lab) is great, it sets an amazingly high standard for clarity of explanation, and for practical combination of experiments and theory, all while being appealing to a broad audience. Most educators would be extremely proud to produce work that's accurate to the standards of a university professor, while remaining appealing to middle-schoolers. I can't imagine what more you want from the content.
he called oxygen the fuel for the fire. the discovery of oxygen was an enormous milestone in the history of science, chemistry, and biology precisely because it's not the fuel for the fire. before that, people knew about fuel, they didn't know about oxygen.
also, he doesn't understand how a bass reflex speaker works. unlike what he said, the port actually decreases the efficiency of the speaker by letting the negative bass note sine waves cancel out the positive sine waves from the front of the speaker, but this is done to tone down the "boominess" of the speaker at its resonant frequency, thus making the speaker more "neutral" sounding, and it's achieved by having the dimensions of the box and the port finely tuned to work most "efficiently" at the resonant frequency.
but in any case, what he says about the "bulk" movement of air (he should probably call it net, i mean all air is bulk by nature) there is no way that the speaker pumping air in and out of the cavity could turn into net movement in one direction. (the smoke ring blower is slowly charged up in one direction, then released in something like an impulse function but loudspeakers don't have that nature) if what he is seeing with his fan-probe is correct, that should have impressed him more and distracted him into studying what exactly was going on (ex: the air coming out was directionally focused from the cone? and sucking back in was amorphous and somehow not detected by his device?) because it is looking for explanation.
tl;dr -- aside from the point about fuel, you mostly don't disagree with him. You have different definitions for the same terms he uses, and you draw your system in a different place than he draws his. Both of you make reasonable choices. A youtube video is not an academic paper, and cannot start by rigorously defining the system under discussion.
he called oxygen the fuel for the fire... it's not the fuel for the fire
I think you're correct here, from chemistry definitions oxygen is not fuel, because breaking its bond consumes energy rather than releasing it. However, I don't think the host is trying to give perfectly precise chemistry definitions here, he's trying to explain how fire burns, and calling oxygen 'fuel' makes it clear to his audience that oxygen is required for combustion. I think your objection here is similar to objecting that voters in the US elect electors rather than candidates -- it's correct, but not necessary if you're explaining the concept of democracy.
the port actually decreases the efficiency of the speaker by letting the negative bass note sine waves cancel out the positive sine waves from the front of the speaker, but this is done to tone down the "boominess" of the speaker at its resonant frequency, thus making the speaker more "neutral" sounding
I don't know much about bass reflex speakers, but I read the wikipedia page in decent depth, and it appears to me that you are wrong, or perhaps using a different definition than the field itself uses. From the wiki page: "This port enables the sound from the rear side of the diaphragm to increase the efficiency of the system at low frequencies as compared to a typical sealed- or closed-box loudspeaker or an infinite baffle mounting... Depending on the exact relationship between driver parameters, the enclosure volume (and filling if any), and the tube cross-section and length, the efficiency can be substantially improved over the performance of a similarly sized sealed-box enclosure." [0]. I bet I can see where your disagreement comes from though -- I think you're arguing that adding the reflex speaker cancels some of the power going through the main speaker, and therefore must result in decreased total_power_out/total_power_in (forgive me if I misunderstand). This is a sensible way to define efficiency, and I think you're correct that total_power_out is strictly decreased. However, there are also other sensible ways to define efficiency, eg, instead of total_power_out you might care about the perceptually-weakest frequency the speaker generates, to ensure the sound is "balanced" to a human ear. You might then define efficiency as num_spectral_bins*min_weighted_spectral_power_out/total_power_in. I have some experience optimizing perceived smoothness, and we used a metric very similar to this. Without fully knowing what you mean or what he means, I think you're disagreeing over terms, not correctness.
but in any case, what he says about the "bulk" movement of air (he should probably call it net, i mean all air is bulk by nature) there is no way that the speaker pumping air in and out of the cavity could turn into net movement in one direction... the air coming out was directionally focused from the cone? and sucking back in was amorphous and somehow not detected by his device?
I think you're agreeing with him here, his explanation matches yours. We can break a full period of oscillation into two sections: a high pressure section (the air molecules being pushed away from the speaker), and a low pressure section (air being pulled back). The high pressure section travels _coherently_ through the air cannon, mostly moving air molecules in a single direction (as you say, it is "directionally focused from the cone"). The low pressure segment pulls air back into the air cannon, but it is _not_ coherent (as you say, it is "amorphous"). During the low section, molecules can flow towards the air cannon from the side of the cannon; they do not have to come from directly in front of the air cannon. If you rewatch that section I think you'll see you're not disagreeing with him. To be fair, more drawings would help communicate it more clearly. You're correct that if you draw your observation box big enough, there can be no net movement from something wiggling back and forth, but I think he's drawing his observation box over the fire. If you look at that system (the air above the fire), you will see net movement.
Watching that dude is like watching a child doing science and then using AI to explain the result. If he makes someone curious enough to do experiments on their own it's still a win though.
It is easy to come away with that idea if you just watch one of his videos. He is very good at clear explanations that get to the essence of an idea and makes it seem simple. Sure, it's at an educational level of detail, but it is accurate on that level.
But if you watch a number of his videos it becomes clear that this is clarity that comes from deep knowledge and sophistication. His channel is also in my opinion notable for having a huge variety of demonstrations, rather than the standard set that is done by a lot of people. There are many things that I've seen only him do, out of my set of science and engineering channels. Which is not to say I know for sure that he is for sure the only one who does them, but it's definitely a more-diverse-than-average set of demonstrations done over the years.
It also, on a more brute level, simply predates AI by a number of years and therefore can't be just an AI script, nor do I see any reason to believe he has switched to using AI to write the scripts.
Prior to “using AI to make videos” he did a phd in chemical engineering. I actually think his explanations and experiments are always very well thought through and presented in a entertaining way
I watch all his videos and they are so easy to understand when to lots of other popular science experiment channels. No high fi stuff, a guy doing experiments with simpler tools available and it's mostly the way he explains things.
Comments
Well, a search for "youtube acoustic fire extinguisher" indicates it has already been invented a few times by people all over the world. The most interesting video is https://www.youtube.com/watch?v=ZvnCQg4w4o8
Was looking for a video on this specific work, but only found this [1] where the English translation seems AI-generated. It reminded me of thermoacoustic refrigeration which I found cool (heh) when I had encountered it many years ago - where the compression and rarefaction of sound waves is used to pull out heat. The fire extinguisher seems to operate on a different principle though - it needs to generate a specific kind of turbulence to push out oxygen from the fire site.
[1] https://www.youtube.com/watch?v=TGO7Jdfll7c
[2] https://en.wikipedia.org/wiki/Thermoacoustic_heat_engine
There is a saying that ideas are cheap. Only delivery matters.
Wasn't it Edison that said that!
Probably stole it from Tesla... :)
It's kinda a throw-away remark in the middle, but I thought it was really cool to realize that speakers produce an on-axis net-blow and an off-axis net-suck.
I'll bet that high school girl's science was better than what's in that youtube (it doesn't set a very high bar)
This channel (The Action Lab) is great, it sets an amazingly high standard for clarity of explanation, and for practical combination of experiments and theory, all while being appealing to a broad audience. Most educators would be extremely proud to produce work that's accurate to the standards of a university professor, while remaining appealing to middle-schoolers. I can't imagine what more you want from the content.
he called oxygen the fuel for the fire. the discovery of oxygen was an enormous milestone in the history of science, chemistry, and biology precisely because it's not the fuel for the fire. before that, people knew about fuel, they didn't know about oxygen.
also, he doesn't understand how a bass reflex speaker works. unlike what he said, the port actually decreases the efficiency of the speaker by letting the negative bass note sine waves cancel out the positive sine waves from the front of the speaker, but this is done to tone down the "boominess" of the speaker at its resonant frequency, thus making the speaker more "neutral" sounding, and it's achieved by having the dimensions of the box and the port finely tuned to work most "efficiently" at the resonant frequency.
but in any case, what he says about the "bulk" movement of air (he should probably call it net, i mean all air is bulk by nature) there is no way that the speaker pumping air in and out of the cavity could turn into net movement in one direction. (the smoke ring blower is slowly charged up in one direction, then released in something like an impulse function but loudspeakers don't have that nature) if what he is seeing with his fan-probe is correct, that should have impressed him more and distracted him into studying what exactly was going on (ex: the air coming out was directionally focused from the cone? and sucking back in was amorphous and somehow not detected by his device?) because it is looking for explanation.
tl;dr -- aside from the point about fuel, you mostly don't disagree with him. You have different definitions for the same terms he uses, and you draw your system in a different place than he draws his. Both of you make reasonable choices. A youtube video is not an academic paper, and cannot start by rigorously defining the system under discussion.
I think you're correct here, from chemistry definitions oxygen is not fuel, because breaking its bond consumes energy rather than releasing it. However, I don't think the host is trying to give perfectly precise chemistry definitions here, he's trying to explain how fire burns, and calling oxygen 'fuel' makes it clear to his audience that oxygen is required for combustion. I think your objection here is similar to objecting that voters in the US elect electors rather than candidates -- it's correct, but not necessary if you're explaining the concept of democracy.
I don't know much about bass reflex speakers, but I read the wikipedia page in decent depth, and it appears to me that you are wrong, or perhaps using a different definition than the field itself uses. From the wiki page: "This port enables the sound from the rear side of the diaphragm to increase the efficiency of the system at low frequencies as compared to a typical sealed- or closed-box loudspeaker or an infinite baffle mounting... Depending on the exact relationship between driver parameters, the enclosure volume (and filling if any), and the tube cross-section and length, the efficiency can be substantially improved over the performance of a similarly sized sealed-box enclosure." [0]. I bet I can see where your disagreement comes from though -- I think you're arguing that adding the reflex speaker cancels some of the power going through the main speaker, and therefore must result in decreased total_power_out/total_power_in (forgive me if I misunderstand). This is a sensible way to define efficiency, and I think you're correct that total_power_out is strictly decreased. However, there are also other sensible ways to define efficiency, eg, instead of total_power_out you might care about the perceptually-weakest frequency the speaker generates, to ensure the sound is "balanced" to a human ear. You might then define efficiency as num_spectral_bins*min_weighted_spectral_power_out/total_power_in. I have some experience optimizing perceived smoothness, and we used a metric very similar to this. Without fully knowing what you mean or what he means, I think you're disagreeing over terms, not correctness.
I think you're agreeing with him here, his explanation matches yours. We can break a full period of oscillation into two sections: a high pressure section (the air molecules being pushed away from the speaker), and a low pressure section (air being pulled back). The high pressure section travels _coherently_ through the air cannon, mostly moving air molecules in a single direction (as you say, it is "directionally focused from the cone"). The low pressure segment pulls air back into the air cannon, but it is _not_ coherent (as you say, it is "amorphous"). During the low section, molecules can flow towards the air cannon from the side of the cannon; they do not have to come from directly in front of the air cannon. If you rewatch that section I think you'll see you're not disagreeing with him. To be fair, more drawings would help communicate it more clearly. You're correct that if you draw your observation box big enough, there can be no net movement from something wiggling back and forth, but I think he's drawing his observation box over the fire. If you look at that system (the air above the fire), you will see net movement.
[0] https://en.wikipedia.org/wiki/Bass_reflex
that comparison says more about you than about how high school girls science is
Watching that dude is like watching a child doing science and then using AI to explain the result. If he makes someone curious enough to do experiments on their own it's still a win though.
It is easy to come away with that idea if you just watch one of his videos. He is very good at clear explanations that get to the essence of an idea and makes it seem simple. Sure, it's at an educational level of detail, but it is accurate on that level.
But if you watch a number of his videos it becomes clear that this is clarity that comes from deep knowledge and sophistication. His channel is also in my opinion notable for having a huge variety of demonstrations, rather than the standard set that is done by a lot of people. There are many things that I've seen only him do, out of my set of science and engineering channels. Which is not to say I know for sure that he is for sure the only one who does them, but it's definitely a more-diverse-than-average set of demonstrations done over the years.
It also, on a more brute level, simply predates AI by a number of years and therefore can't be just an AI script, nor do I see any reason to believe he has switched to using AI to write the scripts.
Prior to “using AI to make videos” he did a phd in chemical engineering. I actually think his explanations and experiments are always very well thought through and presented in a entertaining way
I watch all his videos and they are so easy to understand when to lots of other popular science experiment channels. No high fi stuff, a guy doing experiments with simpler tools available and it's mostly the way he explains things.