Speech intelligibility of virtual humans.

The speech intelligibility benefit of visual speech cues during oral communication is well-established. Therefore, an ecologically valid approach of auditory assessment should include the processing of both auditory and visual speech cues. This study describes the development and evaluation of a virtual human speaker designed to present speech auditory-visually. A male and female virtual human speaker were created and evaluated in two experiments: a visual-only speech reading test of words and sentences and an auditory-visual speech intelligibility sentence test. A group of five hearing, skilled speech reading adults participated in the speech reading test whereas a group of young normal-hearing participants (N = 35) was recruited for the intelligibility test. Skilled speech readers correctly identified 57 to 67% of the words and sentences uttered by the virtual speakers. The presence of the virtual speaker improved the speech intelligibility of sentences in noise by 1.5 to 2 dB. These results demonstrate the potential applicability of virtual humans in future auditory-visual speech assessment paradigms.