A low hum in Jefferson County, Three Mile Bay

Very low hum, which is constant, with a deeper, cyclical hum lasting maybe 3 seconds embedded in it. It's not regular. If I had to give someone a description of it who has not heard it, I would probably say it's like large diesel engine with a very slow idle several hundred feet away (slower than is probably possible for most engines I've heard and run). If you have ever heard the sound a large antenna mast can make in the wind, it has elements of that as well, in that it varies in intensity because of the wind in a way an engine doesn't. If that makes any sense to you. I'm not good at descriptions. Sometime in the 1990's I remember discussing this with my uncle who was a General Aviation pilot with a Piper PA-18 Super Cub (small private plane) who flew quite often. He suggested that there was industry in Peterborough, ON which is about 100 miles away (165 KM) to the west where he had seen large ventilation fans. This sound does seem to come from the west, so I've kind of gone with that explanation since I am on the lake shore and Peterborough is also not far from the lake. There is Prince Edward County, ON, another large peninsula, that is between my place and Peterborough on the Canadian side. Other than that, it's Lake Ontario. We thought it possible that the sound could come from there. At the time that seemed like a reasonable explanation, even considering that you can hear this even when the wind is coming from the "wrong" direction. Normally winds here are from the south, southwest. Peterborough is more west, northwest from here. You can still hear this hum on a light northeast wind. I will add that I occasionally hear the diesel engines of the big ships on the lake just entering or leaving the St. Lawrence River, and when I do, it's obvious what they are. Those big engines have a solid THUMP-THUMP-THUMP to them that is totally regular. You know it's mechanical without even thinking about it. As large as they are, the engines don't turn over that fast, but they are still faster than any cyclical sound from the hum I hear. Not much else to say, except that it's louder this last month (Oct 2018) than I've ever heard it. It's actually what drove me to the Internet to see if there was any explanation. I was really surprised to see how widespread this type of sound is, and gratified to know I'm not the only one that hears it. There's a certain "you're nuts" element to it that prevents me from talking to many people about it.