probably not.

There is very low-freq hum in cities (because of cars wheels, airconds, all those rotating+vibrating things), which can be (un)heard if one goes above and then beyond/down edge of some hill at end-of-city - and will stop hearing it (absorbed by earth mass). But it is difficult to "hear" inside the city as your body also vibrates with it..

Possibly? In this paper they say the frequency needs to be between 2.4-10,000 Mhz and to be over a certain power threshold. Also the individual needs to be within a certain distance and have sensitive enough hearing (over 5000 hz).

No, the hum is around 80Hz normally. This is much higher frequency.