Leaf blowers -- nasty things that should be outlawed in populated areas unless they can pass a noise emission test. Really, I think noise pollution is a vastly underrated hazard. I live in a "quiet" neighborhood that can become earsplitting on a weekend afternoon.

Perhaps quieter automtic robotic variations of the vacuum cleaner driven by electric motors could substitute. Instead of blowing leaves onto your neighbor's lawn they would chop all ingested material into a mulch to be spread evenly over the surface or collected into bags from a roll that could be collected and removed as garbage. It would have to accommodate small discarded plastic toys, candy wrappers, old newspapers, cigarette butts, plastic bags, etc. A sound sensitive switch responsive to screams requiring reset would prevent small children, dogs, cats, squirrels and itinerant snoozing drunks from disappearing.

It would probably work if it doesn't cost too much more.

May have to offer rebates initially to drive interest.

There should be a mechanical way to do this. If we can silence gunshots, we should be able to silence leaf blowers. The interior would resemble an array of ring washers or cones, essentially a number of sections penetrated by the central shaft. As air reaches each section, it is diverted by each divider, resulting in a near silent rush of air.

This assumes, though, that the noise comes from the tube end rather than the motor. It's been a while since I've used one.