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8.9.06

Aural Auroral Encounters
Some say they can hear the Northern Lights
Part 2: Theories abound to explain sounds

By Casey Grove

Lummmerzheim is convinced that not all of the reports of noisy auroras are coming from people hearing wind rustling through trees or snow. Nor does he think that the witnesses are making up their stories.

“You wouldn’t get the same description from hundreds of people over hundreds of years,” Lummerzheim said.

One answer could be that people are getting their sensory signals crossed and hearing color, as do many people with synesthesia, who have described seeing sounds or tasting shapes.

Displaying a graphic showing the sensory inputs from the ears and eyes to the brain, Lummerzheim showed how the signals might get crossed. “It is conceivable that you can have some light come into your eyes, and your brain perceives that as sound,” he said.

Another explanation is that humans might somehow “hear” radio waves—not as part of a giant, brain-rattling electric field, but transformed by some unknown mechanism.

Radio waves usually cannot be heard without a receiver that translates them into audible sound. In a car stereo, for instance, the antenna picks up a very high frequency (VHF) radio wave, and modulates that signal so we can hear it.

In the case of the aurora, the very weak, very low frequency waves that are produced can be picked up by an antenna and recorded at a tape deck without modulation. By some unexplained means, Lummerzheim said, the very low frequency radio waves are being transformed into sound waves.

He played a recording of radio wave noises apparently made by the aurora.

A hissing, roaring sound simply called “lion roar”, was amplified through the packed conference room. Then Lummerzheim played some quick bursts that sounded like they were coming from a laser gun. There were whistles, cracks, and pops echoing through the room.

The recordings were radio noises from a satellite in orbit around Earth while the northern lights raged below. As the satellite passed through different parts of Earth’s magnetic field, different sounds were produced.

Lummerzheim said the real mystery is what turns the waves into sound we can hear. “There’s no known process that can do that with these weak waves.”

The conclusive evidence that scientists would need, he said, is a microphone setup able to triangulate the noise, and some good, old-fashioned luck in finding a noisy aurora.

“I’m interested in it, and I want to understand it,” he said. “I want to understand nature, and that’s part of nature.” Even with so many people interested in this phenomenon, however, finding organizations interested in funding the esoteric research is difficult.

The audience seemed very interested too, and they kept Lummerzheim answering questions for about 30 minutes after the lecture.

“The community support of this program has actually become a selling point for the program,” said Jake Poole, Vice Chancellor for Advancement and Community Engagement.

The presentation kicked off this year’s statewide Science for Alaska Free Lecture Series, coordinated by the Geophysical Institute and sponsored by the University Foundation. The series continues through the end of February 2005. For a full schedule of lectures, visit www.scienceforalaska.com.

ASO contributing writer Casey Grove was born and raised under the Northern Lights in Fairbanks, Alaska. A fourth-year journalism student at the University of Alaska Fairbanks, he works as a student assistant at UAF’s Geophysical Institute, and is also the news section editor of the Sun Star, the campus newspaper.

Related Sites

Science for Alaska Lecture Series

Aurora-related links:

UAF Geophysical Institute daily aurora forecast

Asahi Aurora Classroom

more about “Natural Radio”
Story on Fairbanks aurora research for National Geographic Online by ASO editor Sonya Senkowky

Poker Flat Research Range (rocket facility in Fairbanks that studies auroral phenomena)

NASA collection of aurora images


STORY PARTS

Part 1: Hearing the impossible
Part 2: Theories abound to explain sounds
Part 3: Have you heard the aurora? Send us your story!

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