Ted Weller and I just published a paper describing novel echolocation behaviors in hoary bats.

Here's a link to the paper

Listen to normal and micro calls in this writeup by Science

Nature wrote a short summary.

Press Release from Wake Forest

Email me if you'd like a PDF.

Corcoran, A. J. and T. J. Weller (2018). Inconspicuous echolocation in hoary bats (Lasiurus cinereus). Proceedings of the Royal Society B.  285: 20180441.