Aging effect on audio-visual speech asynchrony perception: comparison of time-expanded speech and a moving image of a talker2s face

In this study, we measured detection and tolerance thresholds of auditory-visual asynchrony between time-expanded speech and a moving image of the talker’s face for older adults. During experiments, words were presented under two conditions: asynchrony by time-expanded speech (expansion condition, EXP) and simple timing shift (asynchronous condition, ASYN). We used 16 Japanese shorter words (four morae) and 20 Japanese longer words (seven or eight morae). For EXP, auditory speech signals were expanded and combined with the visual signals so that the onset of the utterance was synchronous. For ASYN, the auditory speech signal was simply lagged behind the visual speech signal. Detection and tolerance thresholds for auditory-visual asynchrony obtained for older adults was higher than these obtained for younger adults, which suggests that older adults are tolerant of audio-visual asynchrony.