The McGurk Effect

It may sound like he is saying "DA"
Now watch it with your eyes closed, it probably sounds like he is saying "BA".
While watching - open and close your eyes, the sound should change between "DA" and "BA".

(unless you are a pussy)

What causes this?
Our mind takes visual cues when listening to people talk - the video is of a man articulating the sound "GA", so our mind compensates for the mismatch by finding some in between sound of "GA" and "BA", which is "DA"

Our mind interferes with our audio-visual reception all the time. Damn Mind!

oh god- did your balls just drop?
not for pussies!