Loud humming sound

Hi All, Long time lurker first time poster. I live on Vanderbilt btwn Park & Prospect. Does anyone else hear a constant humming noise like a generator or HVAC system on the block running 24/7? It just started about a week or two ago and it drives me nuts when my windows are open. I have no idea where it's coming from.

The cheaply constructed condo building next to me has a HVAC system in the backyard that is amazingly loud. You are probably right on that point.

i had a similar experience in my backyard, turns out it's the kitchen vent for the cupcake shop. The sounds bounces around and it's really hard to tell where it's coming from.