Is there anything about notes and instruments tuning that is not arbitrary? But hear me out: there's few hundred years tradition behind it, at least in the west, so why not follow it for a kid?
"I assume that if the learner drifts later in life by under a semitone, then things will seem like they're between keys." - problem that never occurred to anyone with a perfect or just good pitch.
> there's few hundred years tradition behind it, at least in the west
Not even close to being true!
- There's not been any real convention for most of the history of western music (and no tuning fork anyway) and pitch varied hugely between regions, people and time. Different musician groups in the same church would likely be on different pitches. 415Hz is often used for baroque music but that's just a modern convention, there was no such standard in baroque times. - 432Hz was somewhat conventional at the end of the 1800s, start of 1900s - 440Hz is the "official" standard since then - Many orchestras are tuning to 442, 443, or even 445Hz nowadays
So there's not been any such thing as hundreds of years of tradition, and even now that we do have standards (and ways to measure frequency precisely), pitch inflation continues to be a thing.
>415Hz is often used for baroque music but that's just a modern convention, there was no such standard in baroque times
415Hz is one modern semitone below the standard 440Hz. Many (but not all) baroque instruments were tuned slightly lower than modern ones, and 415Hz is the most convenient slightly lower tuning that retains compatibility with modern instruments by transposing down a semitone.
TIL, thanks.
The 2nd point stands though. A person with good or perfect pitch will quickly tune to another frequency.