[GreenKeys] [External] Re: Tone frequency history?

[Jones, Douglas W]

From: Nick England [navy.radio at gmail.com] -- Friday, October 8, 2021 9:14 AM

>  wonder why 425 Hz tuning forks would have been common? Musical A is 440 and A-flat is 415.3.

It's not that simple.  Historically, there has been a process called pitch inflation in the music industry.  To quote the final paragraph of
-- https://jakubmarian.com/the-432-hz-vs-440-hz-conspiracy-theory/

> Virtually all commercially produced contemporary music is tuned to A = 440 Hz. Nevertheless, most symphony orchestras ignore the standard and tune to 441, 442 or 443 Hz instead, while orchestras specializing in older music may sometimes use a tuning close to the one for which the piece was originally written, which may range from 415 Hz to 470 Hz.

So, 425hz is one note that is historically appropriate as A.  In 1859, the French government set the standard at 435.  The 440 standard dates back to 1939.

          Doug Jones
          jones at cs.uiowa.edu