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Students’ Leaf Blower Suppressor To Hit Retail
(hackaday.com)
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this post was submitted on 20 May 2024
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was posted 3 days ago in /c/Technology, here :
https://lemmy.world/post/15468260
what they did :
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.
And so are our ears. That's why we use db. So 12db is not perceived by us to be 94% quieter.
So its 94% less sound because this seems sound calculated -12db in % with conventional formulas?
How would we describe perceived sound exactly, not many people can imagine something when given a db value? Maybe we should?
When loudness is described there's often lists with examples of things with their typical loudness specified in dB, so you can compare against things you may have heard.
See the image chart here
https://decibelpro.app/blog/decibel-chart-of-common-sound-sources/
I have done a lil research but what i needed was this site. Great resource, maybe even coolguides material.
Well, 93.7% to be more exact. Did you recalculate it yourself the same i did ?
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.
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.
-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.
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.
He has a point though... OVERALL noise was only suppressed 2db. It's only 12db in a specific frequency. EVERY article has more or less ONLY stated the 12db value. It seems more and more these days that you just have to assume that the article headline is at best mostly false, or obscenely misleading.
2db overall... is kind of fucking pointless. I mean... as someone afflicted with hearing problems I know that every db matters. But all this hubbub for something that should just be found, then implemented without all this fanfare... the general public will not care about this, yet I've seen 3 articles on it for some reason.
And most normal people don't understand the logarithmic nature of the db scale anyway. Every 3 db is technically a doubling in power. But it takes 10db for our perception to halve/double.
Because leaf blowers are fucking annoying and we need hope
Taking out the high-pitch whine will make them much more bearable. It's a student project, they did well. This isn't groundbreaking Noble-prize stuff, but it doesn't deserve all the hate it's getting here either.
I did a student project for server room HVAC fans being annoying back in uni, targeted reduction in those annoying or peak frequencies was a totally acceptable outcome as to not disturb operators (was for a simulated patient in the attached hospital). I'm not an acoustic engineer, so obviously take what I'm saying with a grain of salt (did do a lot of safety and risk work though), making things less annoying is perfectly valid if they're not already harmful to your hearing in the first place.
What's cool to me is that it's just printable, so in theory super accessible and anyone could iterate on it if they desired (assuming it gets open sourced)
Agreed. Being in the house and having the shrill component of the blower removed would greatly be appreciated.
I'm not sure I said anything hateful here... I cited facts from the actual paper and described discontent with the articles, specifically the headlines.
The hate is for making a pretty obviously false claim about no power loss. Increasing or even decreasing the exhaust length will affect performance. So for them to add 8” and claim there is no loss of power is quite frankly an outright lie. So it’s being called out, and yet people are defending the asinine claim, it’s hilarious and very concerning as well.
People are also focusing on the wrong information, the total db was reduced by a paltry 2db, not 12db like what’s being talked about.
So they provide sound data that is misleading, and make a claim about power and not provide the data. This just reads marketing piece instead of anything on the actual tech.
They also run between 60 and 100dB, so knocking that down to 48 and 88dB respectively is fucking useless
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.
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.
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.
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.
Yeah, I'm sure you're right
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.
You being downvoted is pretty crazy... Your statement is valid