That noise, described as a low-pitched rumble, has rankled citizens of Windsor since last year, prompting hundreds of complaint calls, leading one resident to create a Facebook page and spurring a senior aide to Canada's foreign minister to visit the city to investigate.
Testing conducted by the Canadian government determined the sound, known by locals as the "Windsor hum," came from the area of Zug Island, a 600-acre, steel industrial site on the U.S. side of the Detroit River, the Canadian Broadcasting Corp. reported.
The only problem? The nearly 10,000 residents of the Detroit suburb have no idea what their Canadian friends are talking about, or hearing.
The mayor of River Rouge, under whose jurisdiction Zug Island lies, told Canadian questioners last year that his city's budget does not allow for testing to track down the noise, according to the CBC. Further, the city's residents say they can't even hear the noise that Windsor residents say shakes their windows, rattles their shelves and may even be making them sick.
"The only place I am hearing noise from is Canada-from politicians complaining," the mayor, Michael Bowdler, told the Wall Street Journal, which first reported on the American response.
Michigan's Department of Environmental Quality did look into the issue last year - examining whether noise could be caused by new machinery used at Zug - but found nothing, according to the Journal.
And pleas made by the Canadians to both the U.S. State Department and the U.S. Environmental Protection Agency have fallen short, with each saying it is a state, not a federal issue.
Meanwhile, Canadian officials are plugging on to try to quiet the noise.
Bob Dechert, the parliamentary secretary to Canada's Foreign Affairs Minister, visited Windsor and Detroit late last month and met with both American and Canadian officials to address the issue, according to the CBC.
Still, the mysterious hum continues.
"The government of Canada takes this issue seriously," Dechert said in a statement. "It is important that we find a solution that works for the people of Windsor."