Wanna know why B and V are the same letter/character in Japanese?

And… what about P? Same.  Same.

Wanna know why F and H work similarly and why they are derivatives of the same phonetic?  And what about Pa?

Ga and Ka?

How about Da and Ta?  Almost, Same Same.

Wanna know why there is a good reason to animate Bs and Vs differently in Lipsync? Or when that might be ok?

Answer:  The McGurk Effect

Source:  http://animateducated.blogspot.com/2013/10/the-mcgurk-effect.html

Additional information: