A mysterious noise has a handful of residents in a Calgary neighbourhood losing sleep and patience, yet no one can find the source of the aggravating sound.

Dana Negrey, who lives in the northwest community of Ranchlands, said he has been bothered by the sound for almost a year.

'It doesn't go away. It's here all the time. You can't relax. You can't sleep.'—Dana Negrey

"It doesn't go away. It's here all the time. You can't relax. You can't sleep," he said. "It's also just the concept of driving home after work, and actually tensing up physically because you know when you walk through that door you can't relax."

Utility companies, fire crews and bylaw officers have come up empty.

Noise engineer Richard Patching detected the steady, faint tone during an interview in the neighbourhood with CBC News. He describes it as a kind of "hmmmmm."

"My machine picked it up. It's quite low, but it's definitely there," he said.

A CBC reporter heard the sound, but couldn't record it.

U of C professor investigating

Owen Watson and his fiancée started hearing what he calls a distant vacuum cleaner sound a few months ago.

"For a month, we lost a lot of sleep trying to find diversionary tactics to mask the noise. There's still noise," he said.

When he complained to the neighbourhood community association, Watson found out he wasn't alone. So neighbours in the northwest community contacted Patching and Marcia Epstein, an assistant professor and acoustic ecologist at the University of Calgary, for help.

Epstein is taking on the mystery hum as a research project.

"On a real basic level sleep disruption is frustrating, so it will lead to irritability, it will lead to decreased ability to withstand the everyday annoyances," she said.

Epstein said it may take years to find the source, if they ever find it.