No my point was that he may not have heard the difference. He expected to hear “Dw i’n”, therefore, he heard “Dw i’n”. So he wouldn’t have noticed. Add in a bit of cognitive dissonance and bingo, we have a cornered person. Someone who will be adamant.
My Dad was convinced Hot Chocolate was singing to a milkman and heard “I believe in milko” to the point that he laughed when he saw “miracles” written down. Also, when he was a primary school teacher (a very short lived career for my Dad) he tells a story of the headmaster commenting that none of the Children could spell February he started to disagree before Dad noticed his own first line on the blackboard…cognitive dissonance again!