"In this excerpt from The Age of Spiritual Machines (Viking, 1999), Ray Kurzweil describes his work in speech recognition." - previous link
"The ‘80s saw speech recognition vocabulary go from a few hundred words to several thousand words. One of the breakthroughs came from a statistical method known as the “Hidden Markov Model (HMM)”. Instead of just using words and looking for sound patterns, the HMM estimated the probability of the unknown sounds actually being words." - https://sonix.ai/history-of-speech-recognition
"Voice Recognition", title of page 82, "Who's who in Artificial Intelligence: The AI Guide to People, Products, Companies, Resources, Schools and Jobs" - By Alan Kernoff, 1986
*grumpy old man shakes fist at ever-changing meaning of words*
https://en.wikipedia.org/wiki/AI_effect
https://www.kurzweiltech.com/kai.html