In response to @wendell's comments on the Alexa's abilities:
Here's a demo I made illustrating some fundamentals of audio and how I think the Alexa can tell which voices are real. Quick and dirty mix on the VO.
Sample audio is here, in case anyone wants it.
Downloadable original video is here.
Also, according to some arbitrary website, the range bats are in varies from 20k-108k, depending on species.