"like someone claiming to hear the sound made by someone else
in the same room when they blink"

Hi there Guido

I now understand, thanks :o)

Um, I would find it hard to discount someone else's sensory
experience, as I can't percieve the world as another does.

I remember seeing a boy on TV that could hear his neighbour a number
of houses down the road from him hoover, and found it painful. To me
this seems implausible, but his mum looked into why he would seemingly
randomly cover his ears and get distressed, and found that reason.
Maybe some people really can hear a blink!

I seem to remember reading somewhere that synasthaesia is more common
in autistic people than in NT people. Again, it isn't part of the
diagnostic criteria, it is just a trait that recurs.

Robin