Guessing they probably got a good grade on this assignment!

A group of engineering students at Johns Hopkins came up with a silencer for leaf blowers that makes them 37% less loud.  They’ve already signed a deal with Stanley Black & Decker and expect them to be available to buy within two years.  

Overall they workshopped more than 40 versions of a leaf blower silencer before figuring out how to mute the sound as much as they could without taking away the power. The final version separated the air to suppress the air but kept the force of air the same. Johns Hopkins grad and Senior product manager at Stanley Black & Decker Nate Green said: “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,” “This is a really rare and dramatic level of success.”