On Tuesday, resident Melissa Harris was in her house, talking to her husband on the phone, when she heard the noises.
"It was getting louder, so I went to the window and luckily i caught it. It was not even a minute or so. I just stood by my window and taped it. In the moment I had goose bumps on my arm," she said.
Harris uploaded a video to YouTube, pointing out the noises were the same as recorded in three online videos posted in 2013.
That video got millions of hits, sparking theories it could be sky quakes, the supernatural or an electromagnetic activity.
But the City of Terrace quelled the speculation with an explanation — it was a city worker grinding down the blade on a grader.
The CBC asked the city if the same thing happened in this more recent case, but hasn't heard back.
In the absence of an answer, residents have resorted back to their hypotheses.
Harris doesn't believe it was a grinder.
"It just sounded like horns in the sky. I don't know people say trumpets, but to me it was just like a loud kind of eerie."