Effects of Distance on Visual and Audiovisual Speech Recognition

Abstract

Face-to-face conversations in every day life are conducted over a range of distances. However, previous research provides only limited indications of the effects of distance on visual and audiovisual speech recognition. We report an experiment which investigated effects of distance on perception of unimodal visual speech and congruent and incongruent audiovisual speech using a talking face presented at distances of 1, 5, 10, 20, and 30m and auditory, visual, congruent, and incongruent forms of the syllables /ba/, /bi/, /ga/, and /gi/. Identification of unimodal visual speech was unaffected by increasing distance to 10m, but was impaired at 20 and 30m. However, despite these drops in unimodal visual speech identification, visual speech improved performance with congruent auditory speech at all distances and impaired performance with incongruent auditory speech at distances up to 20m, indicating that auditory speech recognition is influenced by visual speech even when encoded from distant faces. Implications of these findings for understanding visual and audiovisual speech recognition are discussed.