Humming sound with Humidty

My Ford Explorer sings/hums to me when it is humid out only. Changing from accelertator to brake only some times stops the sound.

Is it the engine humming or the chassis? Is it affected by the engine revs or the car moving?

Does it do this whether the AC is on or off?

Does it have a favorite tune? (sorry, couldn’t resist, no offense intended).

I hear it in both front and back of car. Seems stronger on the drivers side, but does seem to come from the engine area. It varies. Yes it does it whethter AC is on or off.
Thanks for asking about the song…it’s just one note and if I was musical I could tell you which one…but it’s a high one and it’s steady.

Could this all be about a belt?

Thanks for responding