Audiovisual synchrony perception for speech and music assessed using a temporal order judgment task.

This study investigated people's sensitivity to audiovisual asynchrony in briefly-presented speech and musical videos. A series of speech (letters and syllables) and guitar and piano music (single and double notes) video clips were presented randomly at a range of stimulus onset asynchronies (SOAs) using the method of constant stimuli. Participants made unspeeded temporal order judgments (TOJs) regarding which stream (auditory or visual) appeared to have been presented first. The accuracy of participants' TOJ performance (measured in terms of the just noticeable difference; JND) was significantly better for the speech than for either the guitar or piano music video clips, suggesting that people are more sensitive to asynchrony for speech than for music stimuli. The visual stream had to lead the auditory stream for the point of subjective simultaneity (PSS) to be achieved in the piano music clips while auditory leads were typically required for the guitar music clips. The PSS values obtained for the speech stimuli varied substantially as a function of the particular speech sound presented. These results provide the first empirical evidence regarding people's sensitivity to audiovisual asynchrony for musical stimuli. Our results also demonstrate that people's sensitivity to asynchrony in speech stimuli is better than has been suggested on the basis of previous research using continuous speech streams as stimuli.