Am I the only one that’s hearing a very odd, low pitched humming noise?

Weird question, but am I the only one that’s hearing strange, low pitched humming noises that seem to be coming from outside? Like, kind of like the sound of a very loud airplane passing by, but it doesn’t pass by, it just hangs in the air. I’ve been hearing it for the past few months off and on, and recently it’s been getting louder and louder. I’ll hear it even in the morning and it’s very bothersome. I’ve asked several of my friends and coworkers if they’ve heard it and they all have. It’s probably nothing, but I’m sure there’s an explanation behind this.