At SDC Billy Brackenridge and I shared use of the soundproof room that was built for the continuous speech recognition project.
(That room was used in a rather dumb Peter Graves movie about hunting for the Yeti.)
Anyway, that continuous speech recognition project was funded by a three letter agency in Maryland who - as we figured out by reading between the lines - needed a better way to know when humans should start listening to a wiretap. This was in the mid-to-late 1970s.