[alansplace]

Originally Posted by bizzybody

I wonder if it's anything like the ominous hum of a BH-209?

In the 31st century Plasguns, also known as Plasma Cannons, are a class of heavy hand weapons intended to defeat modern passive armor.

Old-style plasguns such as the BH-209 run on a microfusion plant, which must "warm up" before firing by converting stored gases into plasma in a magnetic bottle. This process generates a unique acoustic effect described as an "ominous hum", which has been reported by law-enforcement agents as a powerful deterrent.