Why is 432 Hz better than 440? Because 432 is a holy symmetrical number they say..
But Hz = frequency = cycle per second. This makes a 'second' part of the equation. So what's a second and how does it impact the outcome of Hz?
432 / 440 = 0.982. That's a 1.8% difference. If tomorrow one second would be defined 98.2% of the length that a second is defined today, then tomorrow 432 Hz (oh such a nice symmetric number) would sound exactly like 440 Hz sounds today:
432 Hz = 432 cycles / 1 second
440 Hz = 440 cycles / 1 second
432 cycles / 0.982 second = 440 Hz
There is nothing symmetrical about the definition of a second. When it was defined it's purpose was to be a division of the length of a day. A day is a full cycle of the earth around its axis. This rotation is slowing down. 600 million years ago a day had 21 hours. Meaning the spin decreased 12.5% in 600 million years. The difference between 440 and 432 is 1.8%. In 86 million years a day will be 1.8% longer. If we still live then, and we make the second 1.8% longer so that 24 hours equals a rotation (it doesn't precisely), then 440 Hz would sound like what we call 432 Hz today.
See what I mean? It can't be symmetrical because 'second' is an arbitrary figure. Not saying 432 Hz doesn't sound better than 440 Hz. Maybe it does, who knows? But the symmetric stuff, that's just a theory. One which is incorrect.
some = one | here = some | there = one