> I would have thought that perfect pitch is not helpful at all with classical guitar

I guess it cuts both ways. It's very useful to hav perfect pitch when playing single melodies on guitar since the notes on the frets are arranged less linearly than with piano, where you can just look down and know what note your finger is on. However it does get in the way if you have primarily memorized chord shapes, since sliding the shape down the guitar leads to completely different notes depending on where on the neck you are, causing something like an audio version of the Stroop effect. Because of this, when I use a capo I have to make a conscious effort to completely ignore the pitch and only think about finger position when playing songs, since my fingers pressing in familiar patterns leads to completely unexpected notes. It is actually very annoying.

I think one thing that helped me develop 'perfect pitch' is that I was always trying to emulate the right hand melodies of the piano pieces that my brother was practicing in the next room.

I'm gonna give some more unsolicited thoughts on perfect pitch since I really like the topic.

Our parents also made us take music theory classes once a week (this was in France where we had Wednesdays off of school), and I think that the solfège system lends itself to learning pitches more than the letter system of the US.

The letters are seemingly arbitrary (might as well be numbers) with no resemblance to the notes being represented (except B and E), whereas to me the notes sound like someone is saying "do" or "re" "fa" or whatever the note is right in my ear.

My brother and I actually made up solfège-like words for in between notes, so F# for example would be "fin" (french pronunciation, i.e. feuh(n) or fɛ̃) which is way easier to remember, as a modulation on "fa" than the sound of the words "F sharp" which is just more memorization and mapping that you have to do in your head. Now imagine learning the hindu raga system using single letters for each note...you might as well be doing mental algebra (https://en.wikipedia.org/wiki/File:Melakarta.katapayadi.sank...).

There are certain notes which can be trickier to distinguish from each other (especially at very high or low pitches) because the sounds of the notes 'rhyme' with each other, for example 'mi' vs 'si' and 'la' vs 'fa'. Interestingly, the B and E letters do preserve the rhyming effect in spoken English, however A vs F does not, so I wonder if people who learned on the letter system can distinguish A vs F better than solfege-trained people.

> Can you tolerate music that is (deliberately) slightly out of standard tuning?

It's not necessarily that bad, it depends on my expectation and the context. Any false note can be rescued by placing other notes around/after it in harmonious way like in jazz, but if you are expecting a perfect note in advance for whatever reason, then yes it is annoying when it's off. But we also grew up listening to middle eastern/persian music, so half or quarter steps between notes were pretty typical.

It's kind of like asking if a specific color is annoying..it depends what is around it and what the goal of the visual is. You don't get annoyed at the mere presence of a specific shade of blue unless it's because you know that that shade is not supposed to be in the sky.

The term perfect pitch is a terrible term anyway, which probably discourages people from learning the skill.

For example, my brother's perfect pitch is better than mine. He can detect more notes at once and tune an instrument faster than I can. Most people only focus on the detection part of perfect pitch, but he can always instantly produce exact notes without any adjustment (e.g. whistling or singing) whereas depending on the note, I may have to briefly hear myself back and quickly adjust to my expectations. His 'internal voice' for pitch must be stronger (I would assume this phenomenon is why a deaf person like Beethoven can still compose music).

You can actually trick people with perfect pitch if you change the pitch slowly enough: https://www.bbc.com/news/science-environment-22871651; https://journals.sagepub.com/doi/10.1177/0956797612473310

I'll add that I was extremely surprised when we moved to the US and no one here was able to identify notes, and even more surprised by the claim that you must have special genetics to learn it. The early life/critical period part of it makes sense but I'm still convinced that any child can learn it if they try hard enough or receive enough exposure/positive feedback sessions. Kind of like squibs and mudbloods that can still do magic through sheer effort and training, in Harry Potter? Or like "wizards of the third/second order" in terry goodkind's books.

Support for this is that in countries which speak tonal languages, pretty much everyone automatically has perfect pitch. I don't doubt that there are genes that can enhance the trait though. ChatGPT says these genes haven't been identified yet though, and the best evidence I can find is that "The inheritance pattern for perfect pitch observed in these families resembles [...] autosomal dominant transmission with incomplete penetration" (https://www.ucsf.edu/news/2011/01/98114/genetically-set-perf...).