Some residents have suggested that the sound could be caused by a drone being used during the night hours.
But now, reports are coming in from further afield, after one resident in Wylam claimed that he had heard a similar noise earlier this year.
David Farqhar, a retired environmental health officer, said he had reported hearing the noise to the council several months ago.
David said: “It’s wrong that the county council hasn’t received any complaints. It’s received one from me several months ago.
“I’ve been hearing the same sort of thing myself for some time, for maybe a couple of years.
“I can hear it in Wylam and various other locations. It depends on the lay of the land.”
Northumberland County Council said that it had received no reports of the noise in Wylam.
But David added: “In my 30-odd years in the job, I’ve dealt with noise complaints and I’ve a knowledge of acoustics.
“It’s often a difficult thing to locate and a difficult thing to stop.
“The county council just doesn’t have the time to investigate.
“There’s all sorts of things it could be. I’d be interested to find out what it is.”
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