We purchased this brand-new Stihl backpack blower, model BR-500. It's a commercial grade unit, the only they offer that's rated at 65 decibels. The sound reduction comes from several design changes: a slower air speed and volume; insulated plastic shrouding the impeller fan; acoustic muffler (note the bulge) near the nozzle end of the air hose.

It must be noted that here in the USA, blowers' noise measurements are taken from a distance of 50 feet away. In Europe and elsewhere, blower noise is measured at the blower, which makes more sense.

Here we take the BR-500, fire it up, and you can see just how noisy it is, on our digital decibel meter!