A mysterious humming noise is captivating – and torturing – a small Canadian city across the river from Detroit.

The strange sound, which has been compared to everything from a low rumbling to the buzzing of the Star Trek Enterprise engine, has been irritating Windsor residents for six years, The Guardian reports. But in recent months, the so-called “Windsor Hum” has reached agonizing levels.

“It’s past unbelievable,” resident Mike Provost, 62, told the media outlet. “Never have I ever heard it like this.”

The 35Hz sound has sparked wild conspiracy theories, with some linking the noise to UFOs and covert military activity. The humming has also triggered social media outrage. A Facebook group with 140,000 members was created for people to share their discontent.

“Everybody has their own story,” says Provost.

This isn’t the first time the sound has moved the community of 210,000 to anger. In 2012, more than 22,000 people participated in a phone conference to express their concerns about the sound. Some blamed it for rattling houses while others worried it could have impacts on pregnancy.

According to a study by the Canadian government, the sound could be coming from an American industrial area on Zug Island, located near the international bridge that separates Windsor and Detroit. While researchers have been unable to prove their findings, the study has created diplomatic tension between Canadian and American lawmakers.

“This is the equivalent to pushing a snowball uphill,” New Democrat politician Brian Masse told The Guardian. Masse claims he has tried to tackle the noise problem with American politicians, but to no avail.

“I’ve been [to Detroit] and they feel the hum as well,” Masse added.

“We’re trapped in the middle,” says Windsor resident Gary Grosse of the diplomatic struggle. In the meantime, some residents, and even their pets, have turned to anxiety medication to cope with the noise.

“There’s nothing more that Canadian citizens can do,” says Grosse. “It’s like being on a rope that is being pulled in multiple directions.”