In the case of the fouled ice data, it was ice crashing into itself during the big-ice winter of 2013-2014. But Austin was curious: Are there are other sources of sound under the lake as well? There are reams of research on underwater acoustics in oceans worldwide. But when the UMD physics professor and Large Lakes Observatory researcher started to search for data on underwater sound in large lakes, Austin found nothing.

"It wasn't that it was hard to find. It was nonexistent," Austin said of Great Lakes acoustics research. "There aren't any whales or submarines ... or dolphins out there in big lakes, so apparently no one thought it was interesting enough to look at."