The field of speech technology has expanded enormously in the past 20 years or so. Frank Fallside played a major role in its expansion. In his own research he maintained his interest in the computational analysis and synthesis of speech, but he also acquired a research interest in the related areas of robotics, vision, and geometrical reasoning. As the cybernetics of the 1960s developed into the more broadly based information technology of the 1970s, and as information technology merged with cognitive science and neuroscience in the 1980s, Frank kept up with new ideas and techniques, making himself familiar with the relevant work in artificial intelligence, computer science, linguistics, neurophysiology, formal logic, and psychology. His academic distinction was recognized by Cambridge University in 1983 when he was appointed as professor of information engineering.
In his last few years Frank developed a specialized interest in the theory of artificial neural networks and built up a large team of researchers to investigate its many applications. At the time of his death he was working with colleagues in the Department of Zoology and the Computer Laboratory to plan an ambitious research program directed at establishing a ''bridgehead" between engineering and neurobiology. The theory of neural networks was to play a central role in this research, but the theoretical model was to be confirmed by neurobiological measurements and experiment. He was working on a theory of language acquisition, which, by exploiting the typically cybernetic notion of continuous and corrective on-line feedback, would draw on and integrate recent work in both the analysis and the synthesis of speech.
The interdisciplinary postgraduate "conversion"' course that Frank established in 1985, the "MPhil in Computer Speech and Language Processing," is unusual, if not unique, in being based in a department of engineering. It accepts students with first degrees in either arts or science and is taught by specialists from many different departments across the university. As an engineer, however, Frank made sure that, however broadly based and, in parts, theoretical, the teaching was, the students' projects were practically oriented and directly linked to perceived industrial and commercial needs.
As head of the Information Engineering Division in the Engineering Department at Cambridge, Frank carried a very heavy administrative load. He combined this with teaching and the personal supervision of no fewer than 20 research students and, in addition to this and other university work, with the editorship of Computer Speech and Language, with the organization of international conferences, and