> low frequency rumble, which travels for miles and seems to be inescapable at night What do you think is its source? > aircraft noise, which seems to be cons

> low frequency rumble, which travels for miles and seems to be inescapable at night What do you think is its source? > aircraft noise, which seems to be constant over US cities I cannot find the piece of information a.t.m., but I read that in the USA the percent of territory spared from aircraft noise is a tiny fraction - including wilderness and National Parks. Which is bewildering, for a landmass which is largely effectively uninhabited, and graphically a lit-east dark-west shape. It is part of the problem: when you need real natural silence, and you check the most promising places on a map, it is not low density of infrastructure that can grant it: you can very typically go to the middle of nowhere and be overwhelmed by noise from above. (...And from that one lone inhabitant, that one head in the one-inhabitant-per-square-kilometer, that, while apparently not having been forced to live in the desert, seems to hate the silence and fear he would suddenly die if his own noise ceased.) > emergency vehicle sirens Friends living in the USA report that sirens are much louder than in Europe - as they have to stand out of the already loud environment.