Manfred Schroeder was one of the folks involved, along with Jim West, in pioneering work on electret microphones, among many, many other things.
I've just gotten word that he's died, at a very old age.
Rather than eulogize him, let's say it won't be hard to find his accomplishments, including those in audio, (try "Schroeder Section" for instance) on the web here and there.
Getting old sucks. The alternative is even worse.