Do as I say

Can what we hear be determined by what we are seeing at the time? Definitely. Called the McGurk Effect, situations can arise where one's perception of a sound changes if certain visual cues conflict with what we are hearing at that instant. This clip from the BBC show Horizon demonstrates this simply, yet very effectively. Keep your ears and eyes open for this one:

Ain't that some shit? This also explains why I get a headache watching Godzilla movies and get driven crazy when the audio and video are not synced when watching programs or clips.