Back in the 1930s, there was a worldwide agreement that middle A on the keyboard be forevermore be tuned to 440 Hz, thereby making sure that all music and musical instruments would be tuned the same way.
There are those who still disagree with that, saying that 440 Hz is a plot involving crowd control. Some believe that a more natural frequency is 438 Hz. Others think that 432 Hz is better, capable of unlocking the mysteries of consciousness.
If you Google “432 Hz,” you’ll find all kinds of examples of music played to that tuning—and it does sound kinda cool, especially when applied to classical music.
And that’s not all.
There’s an even fringier element that says we should be tuning middle A to 528 Hz because of its alleged divine properties, “forming harmonically in hydrospace”—whatever that means.