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Seminar Details

Date 7-4-2004
Time 16:00
Room/Location 322 , Sala conferenze, 3 piano
Title Kac II: Can you hear the shape of the vocal tract?
Speaker Professor E R Pike - F.R.S.
Affiliation Clerk Maxwell Professor of Theoretical Physics King's College, London
Link http://www.kcl.ac.uk/
Abstract Abstract. Using methods of inverse problems, which are widely applied in optical superresolution and other modern theoretical studies, we will outline advances we have made in the last three years in the development of a new theoretical basis for the study of speech. By analysis of the acoustical Klein-Gordon equation, known slightly in the field of musical acoustics but scarcely referred to elsewhere, and not at all in speech acoustics, it has been possible to develop a wave-mechanical theory of speech in exact analogy with quantum-mechanical inverse scattering problems. This work leads to major new insights and simplification of long-standing, apparently intractable, problems in plane-wave speech acoustics. In particular, a time-independent perturbation analysis of the straight-tract solutions of the Klein-Gordon equation shows that it is precisely the variation in local potential energy that defines correctly the perturbation. Consequentially, it appears that a somewhat inaccurate definition of an acoustical `many-to-one' mappings problem currently exists, the inverse solution of which has been an unsolved problem for researchers worldwide for over half a century. Our analysis indicates a method for the ultimate compression of the speech wave and all 28 vowels in the main phonetic alphabet have been simulated using a bitwise-parameterisation of the potential function. Such a compression has been the goal of researchers since the advent of digital signal processing, and is inextricably linked to the question of `acoustic invariance' and the development of more robust commercial speech systems for recognition and other applications.
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