What would you say if I told you that one of the year’s best ambient/drone albums was made from field recordings of bats? That’s the story being Ultrasonic, the 8th album to be released under the Field Works name. Stuart Hyatt, the man behind the project, recorded the sounds made by bats in Indiana. From there, the recordings were used by a group of prodigiously talented musicians — including Kelly Moran, Noveller, Eluvium, and Christina Vantzou — to create a series of stunning ambient soundscapes. I talked with Hyatt via email about the project’s genesis and the permutations that this album underwent en route to its completion.