You can’t hear the noises bats make — they’re too high-frequency for human ears. But slow them down to audible range, and voila: It turns out they’ve been singing the theme song for the 1960s Adam West Batman series.
OK, so these guys had a little help. Human accomplices changed the pitch of the ultrasonic squeaks so that they could be heard, then plugged them into a “bat organ” — a keyboard where each key corresponds to a different bat noise. Then arranger Ulrich Seidel played the Batman theme on the organ. But we know it’s what the bats were going for all along.
The Batman theme, produced from sounds made by bats, Improbable Research.