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of a 1,000 words, reasonably fast response times, and less than a 10% error rate.
       The main government contractors included, Carnegie Mellon University (CMU), Stanford Research Institute (SRI), MIT’s Lincoln Laboratory, Systems Development Corporation (SDC), and Bolt, Beranek, and Newman (BNN). A few other institutions also received a number of sub-contracts. In the early development phase (1971-1973), CMU produced the HEARSAY-I and DRAGON systems and later HEARSAY-II and HARPY. ( futureofcmu-final.html).
       Note that the lead CMU researchers for the DRAGON program, James and Janet Baker, pioneered the Hidden Markov Model (HMM) to recognize continuous speech. An HMM is a sophisticated statistical technique that uses probability distributions to infer the most likely word spoken based on prior continuous (or discrete) speech. ( tutorial/Documents /HiddenMarkovModels.html and /Software /HMM/hmm.html). An HMM maintains a probability distribution over a set of possible observations for each state, making it possible to discern words or phonemes (basic sounds of speech) in continuous or discrete speech.
       The first program developed by BNN was called SPEECHLIS, their second attempt held the acronym HWIM (Hear What I Mean) - see papers/bbn-slp-w-call-020401.pdf for a paper on BNN work). Five years later, in 1976, DARPA evaluated CMU’s HARPY and HEARSAY-I, along with BNN’s HWIM. The speech recognition programs built cooperatively by SRI and SDC were never tested. The software coming closest to achieving the SUR project benchmarks (and may have even surpassed them) was CMU’s HARPY. Interestingly, one of
HARPY’s developers, Fil Alleva, now works on speech at Microsoft (
       Unfortunately, since DARPA did not define the precise details for testing the systems in advance, some researchers disputed the test results. Some researchers believed the project had actually failed to meet its initial objectives, which led to a great deal of controversy. This conflict caused DARPA to terminate funding for the program and even cancel a planned five year follow-up study.
       In 1984, DARPA was once again funding speech recognition research, this time on a larger scale, as part of the Strategic Computing Program (see PC AI 16.5 for information on some of the latest DARPA contacts). Many of the original participants in the SUR project took part in the new program, including CMU, BBN, SRI, and MIT. Private firms also contributed such as IBM and Dragon Systems (now scansoft - Dragon systems roots trace back to the CMU DRAGON program).
       This time, to minimize testing controversies, DARPA and the National Institute of Standards and Technology (NIST) established a standard-setting process that included government contractors, industry, and academic groups from around the world. These improved measurements, and the annual system evaluations (or bake-offs), helped promote rapid advances in the speech recognition field, including the incorporation of syntactic and semantic information.

CMU Takes Center Stage
       CMU was clearly a hotbed for DARPA sponsored speech research in the 1980s and therefore attracted the best and brightest students. Kai-Fu Lee ( presspass/exec/kaifu/default.asp) , a graduate student at CMU,

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