Why 432hz Tuning?

The St Louis Symphony has tuned to 442 for many years. 
 

FWIW, ChatGPT reports that the move for standardized tuning gained ground in the 20th century. From the 1600s into the 1800s tunings varied widely according to region and different musicians. The AI says a standard tuning for Bach and his contemporaries was 415, Beethoven from 430 to 450. 
 

Given the time it took to travel and communicate, and the lack of recordings, it makes sense that there could be wide variations in “standard” pitch by region. The AI does say that it can give incorrect results, but I’d say there’s evidence for a mostly lower standard, but not just 432. 
 

it would be interesting to hear some music played at lower tuning standards. Know of any?  Does John Gardiner tune lower?  

@frogman Thank you for finding this interesting article. I have a few Mozart piano concerti recorded with Gardiner as part of a Gardiner box set. I will say the older pianoforte sounds thin and odd to my modern Steinway ears. Will give them another listen.