JUNEAU (AP) William Sheetz still remembers the night in the Mendenhall Valley 15 years ago when an aurora borealis display crackled in the sky, like static electricity on a shirt.
Sheetz, of Juneau, said he hasn't heard the same noise since, but he's not alone in his experience. People have relayed similar descriptions of aurora sound for centuries, said Dirk Lummerzheim, a professor at the University of Alaska Fairbanks' Geophysical Institute who has spent his career studying the northern lights.
''The Natives that lived in Alaska and Canada and Greenland and Scandinavia, they've been hearing it for hundreds and hundreds of years,'' Lummerzheim said Monday during a lecture at Juneau's Centennial Hall. ''And when the white people migrated up here, they didn't believe it. And then they heard it, too.''
While scientific knowledge casts doubt on the ability to hear the aurora, reports over the years have been too similar to be ignored, Lummerzheim said.
People who claim to have heard the aurora describe a crackling, hissing, rustling or swishing sound, he said. The noise, they report, coincides with movement of the aurora. Most only hear it once or twice in their lifetime. Sometimes, one person hears it, while a person standing next to them does not.
One of the problems with the claims is that sound does not travel fast enough to jibe with reports of the aurora making noises as it moves, according to Lummerzheim. He said there are a number of possible explanations for this.
One idea is that signals get crossed in the sky watcher's brain. Research in rats has shown a small crossover between the lobes receiving visual and audio messages. For humans, that might mean visual information from the aurora is actually, on rare occasions, processed as audio information, so people are actually just hearing what they're seeing.
Lummerzheim said he doubts that's the case. In the 1950s, researchers in Toronto put a blindfold on a man who claimed to always be able to hear the aurora, and, without the benefit of vision, he claimed to still be able to hear it.
Lummerzheim's presentation was part of the geophysical institute's ''Science for Alaska'' public lecture series.
Sheetz, who heard the aurora so long ago, left the presentation feeling more confident in his senses.
Before the lecture, Sheetz had no idea such sounds have been a widely reported phenomenon. The cause of the noise, though, still remains as mysterious as that night in the Mendenhall Valley.
''I still think it has something to do with static electricity,'' he said.
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