*grins* I don't mean to pile on, but yeah, that's not coming across very well. Also, where is the hum coming from then? The statement that it's the hum of the city usually means the noise of a living city. I.e people, cars, everything else. Here you've specifically stripped away all that, so there would not be a hum. Unless you mean the aliens/whatsit are causing a humming noise of their own, in which case you should also make that clear.