was posted 3 days ago in /c/Technology, here :
https://lemmy.world/post/15468260
what they did :“Our product takes in a full blow of air and separates it,” said team member Leen Alfaoury. “Some of that air comes out as it is, and part of it comes out shifted. The combination of these two sections of the air makes the blower less noisy.”
… “It ultimately dampens the sound as it leaves, but it keeps all that force, which is the beauty of it.”
Their design cuts the most shrill and annoying frequencies by about 12 decibels, which all but removes them, making them 94% quieter.
about 12 decibels, which all but removes them, making them 94% quieter.
This “conversion” from decibel to per cent is more than ridiculous.
Why? dB is logarithmic so it’s difficult for people to picture how loud something is, if that’s the only number given.
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Well, 93.7% to be more exact. Did you recalculate it yourself the same i did ?
Your calculation was about energy. But the calculation of energy is next to useless when you are trying to compare two different noises. You need to care about perception.
The perception of noise is quite complicated. But as a rule of thumb: when some noise changes by -10dB, then you hear it about “half as loud”.
Source: I have a university degree in acoustics.
So for the reduction of -12dB here, it will be perceived as “nearly half as loud”. Very different than the “94%” is suggesting.
It’s also only 2db overall, the one frequency they dropped that much.
We agree that the -12dB is what’s important for human hearing … Now, you may agree that the 94% reduction is what counts regarding engineering // fabrication // design.
We agree that the -12dB is what’s important for human hearing … Now, you may agree that the 94% reduction is what counts regarding engineering // fabrication // design.
-2db* and 37%*
Why are you perpetuating the wrong information?
The snippet quoted in the original comments and referenced in subsequent comments refers specifically to the decibel reduction of the frequencies being targeted by the invention, not the volume of the overall sound.
Is it? Because the next sentence in the paragraph (and the only sentence missing in the quote) is the overall sound reduction. Which is far more important and far less misleading than saying 12db and 94% quieter.
Its intentionally misleading to deceive people, and than the general public incorrectly defends it, this is you.
The team reduced the overall leaf blower noise by about two decibels, making the machine sound 37% quieter.
You omitted the most important data, it’s 2db overall, not 12db.
So your own “recalculation” isn’t even in the right ballpark as the correct answer.
Its people that misinterpret the information and perpetuate it like you are doing here that makes these look far better than they actually are.
Just saying it doesn’t decrease the power is a bold claim without providing anything technical to support it.
I’ve read multiple articles and videos and yet this very crucial information is intentionally not included.
The claims are false, you can’t suppress or mute something with a tradeoff, unless they have somehow magically figured out physics anomalies. Would love to see some proof of this claim it doesn’t decrease power output.
Are you saying novel mechanical engineering designs are impossible? That the mechanism of a leaf blower is so near perfection, that a well funded team of 4 mechanical engineering students could not, without VIOLATING THE LAWS OF PHYSICS, have simply found a better mechanism?
I agree with your “show me the numbers” critique, but I find your complete disregard of what may be a better answer without any data at all to be equally foolhardy.
I am saying every single one of these claims have never wound up being actually true since they go against the very nature of physics. Yet people perpetuate the claims and defend them without the supporting data.
So to not provide the data for one claim, while providing the data for another is only done to mislead from the truth.
Sorry for not accepting what they say at face value since it goes against multiple things.
never wound up being actually true since they go against the very nature of physics.
This is an incredibly wild statement when you have no data on the device’s construction or operation.
Youre complaining about a lack of data then making wild assumptions about it with no data.
Not exactly a good scientific method here, mate.
It’s a wild statement to claim it doesn’t reduce power when even increasing the length of the discharge tube would affect its performance, and they’ve added a good 8”. Every time like this comes out without the data to back it up, it’s always false, everytime. If it wasn’t the data would be provided now wouldn’t it? Even just showing the CFM data would be enough, but they purposely omit it.
The fact that they purposely omitted data that they have is extremely concerning, it’s not a bold claim say it’s obviously false. It’s bold to claim something like that that goes against what we already know about physics.
I am sorry you are eating up this “marketing”, it’s why products like this are even sold, it’s hilarious, the amount of people defending this asinine claim is honestly quite shocking, especially on a community like this.
Not exactly a good scientific method here, mate.
Uhh… I’m not the one making claims that goes against common knowledge of aerodynamics and then not providing that data. So sure, wanting someone to prove their claim makes me bad at scientific method…?? Maybe the people defending bullshit claims are the ones you should be calling out, oh wait that you yourself. Give you head a fucking shake lmfao.
You’re right to be sceptical until more data is presented, but saying no claim of progress is ever true is quite obviously a gross misrepresentation of our current reality. You are doing this on digital devices interconnected with millions of users ar staggering speed and latency. Every part of which are scientific claims.
Every claim where they omit the actual data to support the claim is never fully true. Provide the CFM testing data they must have to even make that claim.
There is no valid reason to omit that data unless to mislead.
Unfortunately I don’t agree.
Good reasons to omit details include brevity, legibility, pedagogy and scope.
Showing the supporting evidence for all steps in an evidence chain is simply not feasible, and we commonly have to accept that a certain presupposed level of knowledge as well as ambiguity is necessary. And much of the challenge is to be precise enough in the things that need precision.
They provided the DB data so your argument for all of those reasons is invalid. They could have easily spent a single sentence providing the CFM data. So no, not a single one of those reasons is valid to omit 6 words.
They made a claim, they didn’t need to mention the power claim, but they did. They should have omitted the claim itself using your logic, instead of the supporting data. The argument is flawed itself.
and we commonly have to accept that a certain presupposed level of knowledge as well as ambiguity is necessary.
Like knowing making a discharge tube longer or shorter affects its aerodynamics….? So we know the claim is false already…? Their ambiguity is meant to mislead people with zero working knowledge of the subject… anyone with any experience will see its flaw immediately.
There’s a relevant physics anomaly called a Helmholtz resonator, or more broadly waveform interference.
Destructive interference is a thing. The energy of the vibrations doesn’t go away, however you CAN shift that energy into different frequencies and destructive interference done correctly will effectively shift it into so high frequencies that the vibrations are better compared with heat than with sound (what is heat convection anyway if not extremely high frequency sound? :)
Heat is electromagnetic radiation - photons, sound is mechanical displacement - phonons.
They mostly propagate the same due to being waves, in most other respects they are very different.
Heat convection is an entirely separate process where heat radiation is aided by the movement of the surrounding medium. Where it would otherwise heat up it’s environment, convection keeps the environment from heating up. Compare coffee in a thermos (very little convection) to a cup you’re blowing on (significant convection); more air movement - more cooling.
Also, destructive interference does not at all work like that.
Maybe a more useful analogy could be that waves have like walking animations, where in part of the animation they go up, and in another part they go down. Destructive interference happens when a wave in its’ “up” phase crosses a wave in it’s “down”, meaning the resulting movement looks like nothing. The waves don’t however interact in any way, and will continue on their way and on their own animation cycles.
The shifting and heating parts are technically true but require very specific circumstances, enough so that I’m more prone to believe it’s another misunderstanding of the physics behind this. But I’ll give you the benefit of the doubt.
Even increasing or decreasing the length of the discharge tube will change its power and CFM and they’ve added 8”. There is no way the aerodynamics and the overall performance isn’t affected.
12dB is literally nothing in reduction when the lawn dudes are blasting 60-100db
Decibel scale is logarithmic, which means 10db change is reducing perceived volume by half.
12 dB is a pretty decent reduction if your goal is hearing protection, 100->88 is also bringing it to something that absolutely needs hearing protection to something that’s borderline acceptable for an 8 hour shift depending on your local laws, mine say 4 hours but still, way more comfortable to use.
The team reduced the overall leaf blower noise by about two decibels, making the machine sound 37% quieter.
It’s an insignificant 2db, I don’t know why buddy didn’t provide the relevant information.
Reading the article, reducing the shriller frequencies by 12db is still pretty nice, looks like it’s designed for electric blowers which are already way quieter than gasoline powered ones, already generally in the hearing safe range. 2db overall should still be noticeable though, be generally less annoying.
Eh, I’ll take it though. I live in a fairly quiet part of town but the street has gotten pretty busy in the last could of years. And visually, I guess the street seems to open up making drivers get… spicy now and then. The fucking motorcycles, man. These noisy fucking middle-aged infants making 130 decibels while only going 15mph make me see red. I’d gladly take the lawn equipment noise.
The team reduced the overall leaf blower noise by about two decibels, making the machine sound 37% quieter.
It’s an insignificant 2db, I don’t know why buddy didn’t provide the relevant information.
Decibels are a logarithmic scale, so it scales exponentially. Because of this, reducing by just ten is actually very significant and would reduce the perceived volume by half, and would reduce the actual sound pressure even more than half.
The team reduced the overall leaf blower noise by about two decibels, making the machine sound 37% quieter.
It’s an insignificant 2db, I don’t know why buddy didn’t provide the relevant information.
Electric is so much quieter. They have them in Singapore
The gardener in my last apartment replaced all of his powertools (mower, blower, trimmer, …) with electric ones powered by an accu-pack he carries on his back. This is an absolute game-changer! I could actually sit outside again and even do stuff for work, when he was there.
This thing influence how air moves through it, so it would make electrics more silent too
This was designed for electric leaf blowers, not gas leaf blowers.
Electric leaf blowers are much much better, but they’re still loud, and that’s what these students were attempting to address.
The video in the article shows them testing with an electric leaf blower.
MAKE GAS LANDSCAPING TOOLS ILLEGAL
Give away free electric tools if they trade in their gas ones. It’s so bad for health to be huffing 2 stroke fumes all day every day.
Edit, I realize that this is meant for a electric leaf blower since it would do fuck all for a gas one. Doesn’t change my opinion about landscaping tools tho
“Electric leaf blowers are already far quieter than their gas-powered peers, but they still aren’t the kind of thing you’d like to hear first-thing on a Saturday morning. Looking to improve on the situation, a group of students from Johns Hopkins University have successfully designed a 3D printed add-on that manages to significantly reduce the noise generated by a modern electric leaf blower without compromising the amount of air it’s able to move.”
First two sentences of the article.
I don’t know mate, I wouldn’t replace my electric tools–drills, grinders, saw… with gas ones. But these outdoors tools are a different kind of beast. I’ve only used an electric chainsaw and it was an absolute crap, maybe there are better ones but it was crappier than the smallest and shittiest gas chainsaws I’ve used, and a cord around you in that setting isn’t great either.
The problem with electric gardening tools is they aren’t that feasible for contractors.
Batteries don’t last long and take a long time to charge, so it’s just not an option when you’re working all day. Corded means at every location, you have to figure out outlets, extension cords, fuss with tangles and obstructions, etc.
If you’re doing your own lawns, yeah, you can probably get into a workflow that works for you. But a lot of people hire out for landscaping.
Gas being a better energy source than batteries in every way except for the health and environmental issues is a real bitch and why this is such a problem. Cords are a hassle and you will need a lot recharging batteries all the time, so you notice the downsides immediately and acutely. These are solvable problems though. Even running an efficient gas generator would be better for the health of landscaping contractors than being around 2 strokes all day.
Fuck that shit, all the gas lawn tools should be backwards converted to run on hydrolysis-produced rocket fuel, feasibility and efficiency and safety be damned.
Not true, keep extra batteries and put a solar panel on your rig (vehicle or trailer) to charge the dead ones while you work. Maybe keep a battery generator for cloudy days.
Look again! I have a dewalt chainsaw, and I love it. I burn about 13 cords of wood each winter as it is our primary heating source. It runs and runs and runs.
I think the key is to keep the chain sharp. I use the timberline sharpener, and it gets the chain razor sharp, which means less stress on the motor and longer battery life.
They already are in many communities. Enforcement is an issue.
Why do leaf blowers exist in the first place?
So annoying twats can be annoying.
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For the stupid maybe.
Turns out they number around 70 million in the US…
They do the same thing with vehicle air intakes to eliminate annoying sounds and make the car sound more throaty. Don’t forget about cars that have engine noises come through the stereo. People think they need to “feel the engine” in order to drive. I would rather it be completely silent, not that’s not possible because of tire noise.
Luxury sedans have done a damn good job at shutting out road noise for a long time now, but there are obvious (and less obvious) costs associated with that.
Somebody tell Kate Blanchett
??
I want the stl!
I’ll wait until I can 3d print my own. I’m not paying for a hunk of plastic.
Lol what do you put into your 3d printer?
Based on how it works, (not how they say it works) you need a different geometry depending on the frequency. So it’s only going to work at select rpm.
It squashes the fundamental and certain harmonics and fractional harmonics.
Since I probably won’t be able to patent the idea myself anymore, maybe I’ll publicly disclose.
If anything changes, and you have an STL or 3d model you can still sell it.
But a rake is not powerful, you want proof? It barely makes any noise!
Lol also thrice the arm workout.
Not gonna 3d print a rake.
Maybe a baby rake for sand or something
Let me help you with the correct wording: ‘Power to noise’-converters. You’re welcome.
Why isn’t there video of this yet? I didn’t care at all what an article says. Show me the video
There’s a video at the bottom of the article. https://youtu.be/ISgHpUDeLBw
Good. I fucking hate leaf blowers.
The best invention against leaf blowers so far is the scrapyard.
There’s no way this won’t affect the final CFM or Velocity of the air.
This would be no different than running it at a little less than 100% power, but wastes that energy instead.
Why else would they not provide any technical detail, even a wind velocity test would be huge FFS.
I don’t know, it sounds like it slightly redirects only the air at the margins that contacts the blower tube, which reduces turbulence. The noise reduction is due to the decreased turbulence, not a reduction in airflow. If I had to guess, the actual reduction in airflow is probably negligible, and they don’t describe it in more detail because they’re trying to commercialize it
So they could provide the testing data to prove it. Even the numbers, don’t need a full detailed video.
The lack of proof to their claims is concerning.
They’ve made a claim they should have known would need to be verified, eventually…… its bush league for that on its own.
You seem really worked up about these undergrads’ project
I thought having a conversation about the validity of their claims would be an okay thing to do in this community?
Or are you saying this place is for something else?
You demanding more evidence right now and saying these students’ project “is concerning” is not having a conversation about the validity of their claims, it’s just being petulant. Saying, “I’ll be interested to see the specs” or “I’ll keep an eye out for testing data before I believe this” would convey the same thing without coming off like an asshole
It’s data they should have had to begin with, they made the claim. Of course it’s going to be questioned, they could have been upfront with the data.
What other reason would they omit it? Other than to mislead if it wasn’t actually 100%.
It’s funny how I am “demanding” something that would be just basic decency to include along with their claim, they provided the data for the sound after all……
They are almost certainly restricting the amount of information they release under the advice of the legal team at the University, in preparation for the impending commercialization. I agree, it’d be great to have the details and to live in a world where all information is free and open. However, we don’t on both counts. The assumption that they could only be attempting to mislead people when this isn’t even a product for sale yet, is at best naïve and at worst willfully obtuse.
They wont release anything because the design is being sold to black&decker, yay
As soon as it’s out to market someone will clone it and have an STL available
no.
see my comment above.I’ve read the article attached, the article linked in that, and the video linked as well.
Not one talks about anything technical other than it doesn’t decrease the power, so where’s the stats to prove it? You can’t silence or muffle something without a tradeoff, we ignoring basic physics here?
So what is it do your think your non-informational comment is proving? Theres no test information to support the non power diminishing claim, and I call bullshit from basic physic principles.
Are the majority of people who use leaf blowers regularly really going to buy/use these?! I think the leaf blower droning is almost a relaxing noise to me but those god forsaken commercial mowers are a little annoying
