Early theories suggested people in Dollard des Ormeaux were hearing echoes of a Pointe-à-Callières Port Symphony. But those events happen at 2 p.m., and the sky trumpets were reported during the evening. Would sound have carried that far anyway? It's about 25 kilometres from the Old Port to D.D.O., and sound travels at Mach 1, so ... we don't know. Other atmospheric conditions would have to be factored in.
The Montreal Gazette asked a spokesperson at Environment Canada whether there any been any unusual meteorologic conditions Sunday night. "Not that we're aware of. There were no reports of anything in the Montreal area."
Witnesses to the sound say there was little to no wind at the time.
Montreal Gazette Facebook followers had a field day with the mystery. "Don't worry, Quebec will find a way to tax it," posted one reader. "Could they be clearing snow out there?" suggested a reader.
From another, what would seem to be the most obvious answer: "The wind does that sometimes, like with a pan flute." Then from the bottom of the earth: "We heard it here in Australia on Sunday. ... Birds went ballistic. Whether it's atmospheric radio waves or it is a warning, I know what side of the fence I would rather be on."
You can listen to the audio here.
Comment: For more in-depth coverage, check out our SOTT report on this strange phenomenon:
Strange Noises in the Sky: Trumpets of the Apocalypse?
Strange sounds were heard in Montreal in 2012 also. Link.