The Quiet Communities web site has an update on this same paper, highlighting its implications -- including what it means for human beings (or animals) that are both very close to the equipment, and very far away.
For those in very close range, leafblowers can produce sound-at-ear-level of 100 decibels or more, well into the damaging range. And for those many hundreds of yards away, the low-frequency noise typical of leafblowers can penetrate walls, windows, and other barriers that would stop different kinds of sound. The Quiet Communities post quotes Erica Walker, author with Jamie Banks of the journal article:
Sound from leaf blowers and a hose vacuum—equipment commonly used in landscape maintenance—was over 100 dbA at the source and decreased over distance. However, the low frequency component persisted at high levels. “From a community perspective, the sound ratings supplied by manufacturers do not take frequency into consideration,” said Walker. “Our findings suggest that reporting more information on a sound’s character may be a step in the right direction,” she adds.
Worth reading in full.