It resembles the sound of the mothership in Close Encounters of the Third Kind, or the snarl of a long-dead dinosaur crawling back out of the Earth's crust, or simply the wailing of the coming apocalypse.
Whatever it was - even if completely benign - the thundering sounds over Saskatoon recently were alarming enough, and loud enough, to stir Ernie Werezak awake and compel him to grab his camera and start recording.
According to Werezak, who posted the footage on YouTube, he was jolted out of bed by the sounds, which he says seem to be 'in the air,' around 5 a.m. last Saturday.
YouTube user GTIkitty commented on the video and confirmed also hearing the sounds.
"My spouse and I also were awoken to this strange noise," said GTIkitty.
"Was kicking myself for not recording this, so glad someone else was able to get this.
"It happened the first time at 0430 and then again shortly after 0500 early Saturday morning."
This is only the latest in a series of videos that have hit the web since early 2012 that capture strange but similar sounds around Saskatchewan.
Story continues below the video
After that instance last year, University of Saskatchewan physics professor Jean-Pierre St. Maurice told CTV News the cameras were likely picking up noise from an electrical antennae. The sounds could also be caused by electromagnetic noise in the ionosphere, he added.
"It's not actually noise," said St. Maurice.
"It's like the electromagnetic waves emitted from the aurora above our heads or emitted by the radiation belt a little bit more to the south."
"I guess you could take that as an answer but you never know if there's another one," he said.
Hat tip to CTV News.