I said I wasn’t going to just link to articles. But this one from MIT’s Technology Journal contains the links I’d otherwise want to research for myself. So have a look.
In brief: there’s been a lot of research over the last thirty years in speech to text rendition, and products on the market. But MIT appears to have cracked two additional problems. First, many lecturers aren’t native English speakers – a top university is a polyglot, international community. So software that’s designed for standard English (or American) won’t do. Second, of course, in lectures there are many specialist terms not in a standard lexicon (whatever the subject).
So for MIT to offer its students a Lecture Search online tool, based on videos of lectures, is pretty remarkable. Read the story here: Searching Video Lectures (MIT Technology Journal, 26 Nov 2007).