Disproving visemes as the basic visual unit of speech

Abstract

Visemes are groups of phonemes that are considered visually indistinguishable, but there are many doubts regarding their use in visual speech recognition. In this thesis, a visual speech recogniser is constructed to test the validity of visemes. Examining the phoneme output of the recogniser shows that it is not possible to construct a viseme grouping that exhibits the required phoneme confusion characteristics. This thesis proves that phonemes, not visemes, are the basic visual unit of speech.