I'm 50 in Johnsburg IL. I also hear the low pitch humming that sounds like an engine running nearby. I've had high-pitched ringing in my ears for about 25 years (or longer). I associate that with my tendency to tense up which puts pressure on the ear structure. Only recently do I hear this extra humming at my house. I thought it was a fan, but then one day the town electrical grid shut down due to bad weather. I still heard it without any electricity. The humming is prominent in my left ear. It is strongest at home, but I do hear it in other places. When environmental sounds are quiet, that is when I may hear the humming. I've heard it at work and at church. It feels like an outside vibration, even affecting my whole body. But I can't hear the sound. Earplugs do not work. Noise-cancelling ear buds (without sound playing) don't work either. Headphones/ear buds with sound playing does succeed in masking it completely (or watching TV without headphones tends to mask it). If I am active in my home, I don't hear it. Only if I'm sitting or laying down without headphones will I hear it. It's loudest when I lay down in bed. However, I am able to fall asleep and I don't wake up to it.
Q