I do know that my wife and I cannot hear the same name in the Laurel - Yannie example, but she is definitely hearing what she say she hears. I on the other hand cannot see how she does not hear what I am hearing.
But I do think it is in our brains, because sometimes she hears the same thing that I hear. A told her she is a switch hitter. (LOL)
My 20 year-old daughter just had me listen - I hear Yanny - so there goes my theory on it being the higher frequency thing!
She said something like “Well - like DesCartes said ‘I think, therefore I am’. The only thing we can be sure of is the thoughts we are having - all of our senses might just be tricks and presenting an illusion to us.” I suppose, but I doubt it.