Editing DARPA Speech Understanding Research (section)

===== HWIM =====
Similar to Hearsay-II, the Hear What I Mean system was also knowledge-based, but it employed a more explicit scheduling approach based on human problem-solving methods. The process began with the identification of the most certain words, which served as 'islands of certainty,' and then leveraged these to iteratively expand both bottom-up and top-down identification processes.<ref>Schwartz, R., Barry, C., Chow, Y. L., Deft, A., Feng, M. W., Kimball, O., ... & Vandegrift, J. (1989). The BBN BYBLOS continuous speech recognition system. In ''Speech and Natural Language: Proceedings of a Workshop Held at Philadelphia, Pennsylvania, February 21-23, 1989''.</ref>

Unlike using a central mechanism as in Hearsay-II, in this system, knowledge sources would communicate with each other and share processed data<ref name=":1" />. To score phoneme and word hypotheses, Bayesian probabilities were utilized. Furthermore, the system represented syntax using an Augmented Transition Network, presenting a greater challenge at the syntax level compared to previous systems. As a result, this system was able to accept 1,097 words, however, yielding more than 50% semantic error<ref>Lowerre, B.T. (1976). The HARPY speech recognition system.</ref> and thus not meeting the goals of the project.