Maybe I'm too cynical, but these things strike me as money grabs that prey on peoples' understandable paranoia surrounding privacy. I'm happy to be convinced otherwise, but those were the first impressions of someone with a passable knowledge of how such devices ostensibly function. Unless it's doing something special I'm not aware of, a fairly basic filter on the microphone to limit any sounds outside of audible midrange would likely render these devices moot.

unless of course that inaudible signal is actually a high power laser to destroy the offender.. but i'm not comfortable wearing laser goggles everywhere.

thought : a gadget that says words in my exact tone intonation and style incessantly while I talk to throw the speech-to-text systems off via garbage injuection -- boy that'd be obnoxious to compete with in a conversation.

tl;dr : sounds like a new high priced ultra-sonic mouse deterrent.