A national park in vermont has a new exhibit featuring digitally-altered recordings of bat calls, NPR reported. 

The recordings were taken from members of two species prone to a disease called white-nose syndrome, which has caused countless bat disappearences in recent years according to geologist Kent McFardland. McFardland recorded the sounds in 2001 when he was taking an inventory of bats in Vermont. 

Digital media artist Andrea Polli got news of their disappearance and embarked on a project meant to celebrate their unique sounds. 

"I thought it would be fun to play with the fact that they sounded to me really electronic," she said. 

She manipulated the bat calls, which occur at a frequency humans can't detect, made them audible, and looped them. The result is what NPR desribed as "a ghostly funeral dirge in the middle of the national park where they used to thrive."