Understanding language is a central feature of being human. We also make substantial use of non-speech audio for navigating the world, though we're not always consciously aware that we're doing so. However, machines that always listen can seem like a creepy invasion of privacy if the eavesdropper might be reporting back to some third party.
Robat, a robot that navigates by echolocation.
Google's assistant demo: was it faked? was it ethical?
Maybe speech recognition caused unwanted dollhouse orders or maybe it never happened.