I've found another collection of references on speech scanning/recognition, the February 1989 CACM, p.193, contains 38 references going back to 1980. It'd be an interesting exercise for anyone with access to a large library to trace back through these (some of them look promising, like a 1980 book "Trends in Speech Recognition" from which a number of references are taken) to see how far back you can go and at what point certain things became feasible. The CACM references would be a good starting point for a search. Peter.