At relativistic speeds there is an optical effect called Terrell rotation causing objects passed by to seemingly rotate.
As bats use sound rather than light when echo-locating, at what degree would the experience the Terrell rotation? We know the speed of sounds in air, and can estimate the speed of bats and a field of view. Given all this, to what extent would the bats experience this effect? Not at all, barely visible, or pronounced?
If this effect is not experienced, what do they experience?