This paper introduces the session on advanced speech recognition technology. The two papers comprising this session argue that current technology yields a performance that is only an order of magnitude in error rate away from human performance and that incremental improvements will bring us to that desired level. I argue that, to the contrary, present performance is far removed from human performance and a revolution in our thinking is required to achieve the goal. It is further asserted that to bring about the revolution more effort should be expended on basic research and less on trying to prematurely commercialize a deficient technology.The title of this paper undoubtedly connotes different things to different people. The intention of the organizing committee of the colloquium on Human-Machine Communication by Voice, however, was quite specific, namely to review the most advanced technology of the day as it is practiced in research laboratories. Thus, this paper fits rather neatly between one given by J. L. Flanagan (1), which discusses the fundamental science on which a speech recognition technology might rest, and those of J. G. Wilpon (2), H. Levitt (3), C. Seelbach (4), C. Weinstein (5), and J. Oberteuffer (6), which are devoted to real applications of speech recognition machines. While it is true that these applications use derivatives of some of the advanced techniques discussed here, they are not as ambitious as the purely experimental systems.In keeping with the theme of advanced technology, J. Makhoul and R. Schwartz report on the "State of the Art in Continuous Speech Recognition" (7). They give a phonetic and phonological description of speech and show how that structure is captured by a mathematical object called a hidden Markov model (HMM). This discussion includes a brief account of the history of the HMM and its application in speech recognition. Also included in the paper are discussions of extracting features from the speech waveform, measuring the performance of the system, and the possibility of using the newer methods based on artificial neural networks.Makhoul and Schwartz (7) conclude that, as a result of the advances made in model accuracy, algorithms, and the power of computers, a "paradigm shift" has occurred in the sense that high-accuracy, real-time, speaker-independent, continuous speech recognition for medium-sized vocabularies can be implemented in software running on commercially available workstations. This assertion provoked an important and lively debate that I shall recount later in this paper. The HMM methodology allows us to cast the speech recognition problem as that of searching for the best path through a weighted, directed graph. The paper by F. Jelinek (8) addresses two central and specific technical issues arising from this representation. First, how does one estimate the parameters of the model (i.e., weights of the graph) from data? This is usually referred to as the training problem. Second, given an optimal model, how does one use it in the recognition ta...