Related: A documentary[0] about Daniel Tammet[1] who also has synesthesia and set the European record for reciting pi from memory by recounting to 22,514 digits in five hours and nine minutes.
I was super interested in Daniel Tammet, and read his book in the past.
But then I read Moonwalking with Einstein, about a journalist's attempt to win the US memory championship. Most of the book is just about that, but he does spend a chapter critizing Daniel Tammet, basically accusing him of lying about his condition and using simple mnemonic tricks to do his "feats of memory". His case is very compelling (e.g., Tammet being inconsistent in answering how numbers "look like" in different interviews, forum posts by Tammet on mnemonic techniques before he was famous, etc).
Yes, I was looking for this. When I started reading the OP's post I immediately remember Daniel telling how he visualize numbers.
If I remember well some natural talented musicians (that didn't do a lot of formal training), also see notes/music in colors.
This made me think if I had some special talent relates to this kind of visualization but the only thing I associate with colors are places, which might explain my good orientation skills but nothing more than that.
But then I read Moonwalking with Einstein, about a journalist's attempt to win the US memory championship. Most of the book is just about that, but he does spend a chapter critizing Daniel Tammet, basically accusing him of lying about his condition and using simple mnemonic tricks to do his "feats of memory". His case is very compelling (e.g., Tammet being inconsistent in answering how numbers "look like" in different interviews, forum posts by Tammet on mnemonic techniques before he was famous, etc).