It’s not often that undergraduate students put their names on a patent application before earning their degrees. It’s even rarer that a Fortune 500 company says it wants to produce the device those students worked on.

Both are happening now, as a group of four Johns Hopkins University students prepare to walk across the stage at graduation. The students, as part of yearlong engineering class, created a snap-on accessory that reduces the noise produced by a leaf blower by nearly 40% — without reducing the power of the air being pushed out.

The students, Madison Morrison, Michael Chacon, Andrew Palacio and Leen Alfaoury said they probably spent about 20 hours a week working on the projects since last August.

“The design has changed a lot,” Morrison said.

The product is patent-pending, and program sponsors at Stanley Black & Decker thought it was so successful that the company intends to start selling the accessory in the near future.

“This team not only developed a fantastic solution, but they excelled in communicating their ideas and working together to progress them,” Nate Greene, director of platforming strategy at Stanley Black & Decker, said in an email. “We’re looking forward to further refining the design so that our end-users can experience its full benefit as soon as possible.”

The attachment does more than reduce or muffle noise. It also uses passive sound interference to almost entirely eliminate the harsher, piercing whir associated with leaf blowers.

There’s no official timeline for when the product might be for sale. But the students think it could be tweaked or modified and applied to other noise, air-based tools, such as vacuums or hair dryers. The project belongs to Stanley Black & Decker, but the students’ names would be on the patent.

How do you make a quieter leaf blower?

At the beginning of the school year, the students were all given an assignment: Take a leaf blower and make it quiet. The group said they went through at least 40 iterations before landing on the final design.

“It was extremely open-ended,” Palacio said.

First, the students had to identify the source of the harsh noises coming from the leaf blower, and research to understand what noises would make the most sense to target for dampening.

The students spent part of the year trying different ideas: One was the passive device they finished with; the other was active noise interference, which means the leaf blower would emit a second noise while it was operating but would cancel out the sound of the blower — kind of like the way some wireless headphones do noise blocking.

But, that kind of a device would be more complicated to manufacture on a commercial scale and more complicated to design. About halfway through the year, they shifted their focus to passive noise interference.

A significant part of their final design was its adaptability, Alfaoury said. A cap attachment that screws onto a leaf blower is much easier to adjust to different models than a specialized, noise-emitting piece of tech.

Chacon said it was maybe September when they were able to 3D print and test their first prototype.

“When we saw that there was promise there and we saw it was actually doing something, man, it was really something,” he said.

The device works by separating the air coming out of the leaf blower and shifts part of it, Alfaoury said. As the air shifts and recombines, the noise created by the air dampens the sound and cancels out some of the most irritating, screechy noises from a leaf blower.

The cap design cuts the harshest frequencies by about 12 decibels, which makes them 94% quieter; the overall leaf blower noise is reduced by about two decibels, making it about 37% quieter, according to Hopkins.

Greene, the Stanley Black & Decker platforming strategy director, is also a graduate of Hopkins. He said the projected demonstrated a “dramatic” level of success.

The final design is likely to be slightly different than the red cap, the students said. Stanley Black & Decker indicated it was going to make the device clear, so that consumers could see the spiral inside that dampens the noise, and add a metal tip to it, for scraping stubborn leaves and debris.

Chacon is moving to California to start a job; Palacio is working locally. Morrison is moving to California to pursue a Ph.D. at Stanford; and Alfaoury is moving back to Jordan.