— The mysterious noises, some call them "booms," being reported across Wake County in recent weeks are nothing new.

"These are not a new thing in North Carolina. I think we've even had them before scientific instrumentation," said Jonathan Lees, a geophysicist at the University of North Carolina at Chapel Hill.

That doesn't mean Lees, who studies seismology and volcanology, has the answer.

"My colleagues and I still consider these a mystery, although I should point out that we've never studied these with scientific instruments like we would use on volcanoes," he said.

From Fuquay-Varina to Rolesville, residents have reported a loud sound, even vibration.

"All of us hear it. All of us see it, but nobody knows what it is," said Kay Gallagher.

Gallagher, of Flemming Fields in Fuquay-Varina, has witnessed what the sound does.

She shared photos with WRAL News, saying the vibration of the sound shattered her mirror.

"They're so loud when they hit - it knocks the lights down from in my closet."

"We hear it frequently," said Bob Stewart, who lives nearby.

Stewart is just one of several neighbors who has heard the booms.

"Sometimes it's like you hear it, and it's like a big dump truck that dropped the bed," he said. "It's almost like a jet breaking the sound barrier or something."

Other neighbors have guessed they are hearing military exercises or some other kind of explosive.

"It just kinda goes on for a second," Stewart said.

Some even suggested an extraterrestrial source.

Lees knocked that one right down. "There are no aliens," he said.

The simplest solution – that the noises are man-made – is likely the answer, Lees said.

But that doesn't mean the noise is coming from nearby.

He points out that different atmospheric conditions can cause sound waves to bounce around and travel long distances. On the right nights, a.m. radio transmissions from Chicago have been heard in Raleigh, he said.

He also offered an environmental hypothesis.

"One possibility is there could be something occurring offshore, on the slope of the shelf," he said.

Jonathan Blaes, at the National Oceanic and Atmospheric Administration in Raleigh, says there is no atmospheric reason for the booms, but he didn't offer any idea about where they are coming from.

"To the best of our knowledge and the dates with which these have occurred, we have no reason to believe these are related to any atmospheric phenomenon," he said.

"You hear it, and you walk out, and you kind of go, ‘What the heck was that?’" Stewart said. "I sure would like to know! Everyone would like to know.”