People who live and work in downtown Halifax are sounding off about an eerie noise coming from the Nova Centre construction site.

Some say the bizarre howling sounds like a spooky spirit, while others compare it to the loud clanging of an organ.

“It sounds like I imagine what a really loud ghost would sound like,” said one Halifax pedestrian.

“It sounds like a banshee,” described a construction worker. “You know that thing, that woman, she’s just yelling at you, she’s right scary and stuff.”

Restaurant employees and hotel guests say they have heard the wailing too.

“It sounded like an organ playing because there was all different notes,” said one hotel guest. “It was quite strange.”

The Twitterverse has also noticed the strange sound, with one user tweeting that he can hear “the ghostly wailing” for blocks. Another Twitter user tweeted his local councillor, Waye Mason, saying the “wind noise … must stop.”

The noise only happens when a strong southerly wind whips through the Nova Centre construction site, with one engineer comparing it to blowing across the top of a bottle.

“There could be some architectural feature or structural feature right now that has a cavity like a Coke bottle, and as the wind blows over it, it would make that whistling sound,” said Michael Wesolowsky of Swallow Acoustics. “We’ve seen that before in other buildings.”

Construction officials tell CTV News the noise is the result of the unfinished roof, and that the strange sounds will be silenced once the roof is complete.

With files from CTV Atlantic's Matt Woodman