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Silencer for leaf blowers picked up by Black & Decker

Silencer for leaf blowers picked up by Black & Decker
The new leaf blower silencer (orange) is an attachment that drastically reduces the most annoying frequencies blasted out
The new leaf blower silencer (orange) is an attachment that drastically reduces the most annoying frequencies blasted out
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The new leaf blower silencer (orange) is an attachment that drastically reduces the most annoying frequencies blasted out
The new leaf blower silencer (orange) is an attachment that drastically reduces the most annoying frequencies blasted out

Leaf-blowers are the bane of suburban Sunday mornings. Now a team of engineering students at Johns Hopkins University has invented a kind of silencer attachment to radically reduce noise, which could be on shelves in a few years from Black & Decker.

There are few power tools that raise a neighbor’s hackles quite like the leaf blower. Sure, others can be loud, but there’s just something about their particular ear-splitting drone that cuts in like a dentist’s drill. Perhaps it's people's frustrating tendency to use them early in the morning, when folk are trying to sleep in. Perhaps it's the knowledge that using a broom or rake would not only be quieter, but also wouldn’t just move all the leaves onto your lawn. Either way, it's the kind of problem engineering students love to tackle.

The team’s design ended up taking the form of an attachment that fits over the end and dampens the specific frequencies blasted out by leaf blowers, without reducing the force of the air. They compare it to a silencer for a gun, or a muffler for a car. The researchers started by analyzing the sounds leaf blowers made, and how they make them.

“The sound that comes out of this leaf blower is very complicated and it contains a lot of different frequencies,” said Andrew Palacio, a member of the research team. “A lot of different notes on a piano would be a good analogy.”

It turns out, among the cacophony that these tools emit are some high frequency noises that are particularly annoying to the human brain. The team designed their attachment to specifically dampen these frequencies, reducing them by around 12 decibels (dB) at 50 ft (15 m), or 94% quieter. The overall noise has come down by about 37% – that means there’ll still be some noise of course, but this device should take the edge off it.

“It's the difference between hearing a high-pitched whistle and hearing what you might think of as wind noise,” said team member Madison Morrison.

It’s not be as dramatic a reduction as other recent leaf blower advances, like that from Whisper Aero last year, which cut overall noise by more than half. But that was mostly a tech demo for the company's super-quiet electric jet engines for aircraft. The new design from the Johns Hopkins team is poised to become a commercial product within the next two years or so.

“It's not just some cool theoretical thing that will sit on a shelf and never be heard from again—this is ready to be mass manufactured,” said Nate Greene, senior product manager at Stanley Black & Decker, who have picked up the pending patent. “This is a really rare and dramatic level of success.”

The team says the design could also be adapted to make quieter versions of other appliances like vacuum cleaners and hair dryers.

Check out the leaf blower silencer in action in the video below.

Hearing is Be-leafing: Students Invent Quieter Leaf Blower

Source: Johns Hopkins University

Why not some kind of air rake? Instead of a concentrated, round stream of air angled downward which tends to blow the leaves back upward, make a wide, flat nozzle that produces a horizontal curtain of air. Put it on wheels to keep it low to the ground and it might be able to do the same job with a lot less energy and noise.
I give a huge thumbs up to this team!
dave be
The electric ones that are pictured are not really the problem. If it works on those infernal gas powered ones that would be the trick.
Gasoline-powered generators also need silencing. Briggs & Stratton (and probably other makes of) single-cylinder engines on those things are extremely noisy. B&S doesn't make or sell replacement effective mufflers.
A friend said that motorcycle retailers discard OEM mufflers because a lot of buyers want loud exhaust. Maybe some enterprising welding shop will figure how to mate a good motorcycle muffler with B&S and other-brand gasoline generators?
My immediate neighbors have their lawns cut/maintained by a company that uses gas powered equipment. They make enough noise to wake the dead while doing their work. I do my own lawn cutting and leaf pickup using battery powered equipment.
Trylon: I use my battery powered lawnmower to vacuum up leaves in the fall,which is much more efficient than using a blower,which produces an air stream that is hard to control. Your idea is already available using a centrifugal blower mounted on two wheels,usually powered by a gas engine.
A friend who majored in horticulture and owns a nursery advised me to mulch the lawn cuttings and leaves rather than collect them. He said they provide food and moisture to the lawn. Some folks retorted that there are substances in the leaves nad grass cuttings that are not conducive to growing grass. It is simply not true as these substances came from the cuttings.
These students have admirably tackled a very mild, almost trivial problem — the exhaust “noise” from an electric-powered blower. Have they researched how many people actually complain about such “noise?” The much bigger problem is the absolutely outrageous gas engines that power all yard workers, especially THOSE blowers that they use for sweeping. Different problem, sure, but let’s get real. This little 3D attachment is only academic kid stuff.