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Hearing is be-leafing: Students invent quieter leaf blower (hub.jhu.edu)

submitted 6 months ago by [email protected] to c/technology

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[–] A_A 165 points 6 months ago (2 children)

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."

Adds Chacon: "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.

[–] cactusupyourbutt 14 points 6 months ago (1 children)

wtf is shifting?

[–] [email protected] 30 points 6 months ago (1 children)

The wording is comically awkward and imprecise. But if I had to guess, they figured out a way to fiddle with how the air is routed through the secondary portion such that the emitted noise is phase-shifted to cancel out the frequencies they’re targeting.

[–] [email protected] 13 points 6 months ago (2 children)

Seems baffling

[–] Tyfud 4 points 6 months ago

Eeeeeeeeeeyyyyyy

[–] [email protected] 2 points 6 months ago

But you can’t deny it has a certain flow to it

[–] curiousPJ 6 points 6 months ago* (last edited 6 months ago) (1 children)

I wonder if that shares the same physics as silvent's compressed air guns.

Silvent’s air nozzles reduce the sound level when blowing with compressed air compared to blowing through open pipes. This is due in part to the reduction in noisy turbulence from using Silvent’s air nozzles, and also because of the nozzles’ special design. Silvent’s air nozzles pass the compressed air through small holes and slots, which raises the sound to frequencies beyond what the human ear can perceive. This allows us to make blowing with compressed air both quiet and efficient.

Could use an even quieter compressed air gun

[–] A_A 6 points 6 months ago

No, not the same ... in your paragraph you describe an increase of the frequency at a level human hearing do not perceive while the other made cancellation of a given frequency using phase shifting and recombination.