When an instrument is tuned to 432hz, it means that what ever notes are in that instrument, the starting point or reference point for the tuning of those notes is A4 = 432hz.  Which means the A note in the 4th octave of a piano tuned to the 432hz musical scale is the reference point for the notes of that 432hz tuned instrument.

For example if you have a crystal singing bowl any note tuned at 432hz, say the note of G.   That G note could be from any octave, depending on the size and thickness of the bowl, but that G note, the corresponding A note in the 4th octave of that musical scale that G note belongs to, is 432hz.

The world is loaded with theories about 432hz / 440hz so much that it has become a debate.  I have spoken to a modern University-trained Music Therapist, who refused to believe there is any difference in the healing properties of 432hz tuned music.  Which doesn’t matter anyway as everyone is entitled to their own belief and opinion.

Despite the disbelief of many in the healing virtues of 432hz tuning, there are some fundamental facts which can’t be ignored, including:

1. Pythagoras defined the modern musical scale we know today, based on the 432hz tuning. (A4 = 432hz)
2. For this reason, the 432hz tuning is also known as “Pythagorean tuning”.
3. Pythagorean tuning is the easiest scale to tune instruments by ear, without any tunining devices, because it is more “in tune” with the natural frequency of human hearing.
5. Pythagoras prescribed music as medicine and created musical devices to produce certain frequencies and harmonics for healing.
6. At some time (in the 1960s) the frequency of concert pitch was changed, from 432hz to 440hz.

In the second world war there were extensive experiments conducted (in a certain European country) with sound frequencies and their effects on the human body and human health.  It was discovered from those experiments, that certain specific sound frequencies can induce certain emotional states, and also certain states of health and well-being, both positive and negative.

A discussion I had several years ago, with a piano tuner best buddy of mine about this change in concert pitch to 440hz. “Don’t talk to me about 432hz” she said with a chuckle, and then told me of many discussions she has had with opera singers over the years, up to 20 years ago, about this tuning issue.  My friend is among the best piano tuners in the country, she tunes concert pianos at the concert hall, before and during concerts.

The older opera singers she spoke to about 432hz tuning, told her they loved it when they got to sing with any of the visiting European orchestras who bring their older stringed instruments with them, and so whole orchestra is tuned to 432hz.   It feels so much easier on their voices and they can feel their voices stronger while singing to 432hz.

So much that they don’t enjoy singing with all the orchestras with newer instruments who tune to 440hz – because singing too much at 440hz tuned instruments, it really does cause them discomfort which affects their voices.  They despise singing with some of the American orchestras who insist on tuning to 444hz !

It’s important to note that not all European orchestras have the older instruments.  When at home they do always do their own singing practice without any instruments, to their natural voice (which is 432hz) which keeps them in top shape.

These older ladies are well experienced and in tune with their voice and their health, and claimed that the modern vocal health problems experienced by modern singers, such as nodules on the vocal chords etc. never happened in the “olden days” with 432hz tuned instruments!

I do believe the testimony of these knowledgeable and experienced ladies, and I do believe their ablity to discern the difference in their singing when singing at either 432hz or 440hz, or 444hz tuning is real, as they had no reason to say this other than speaking their truth.  They were taught how to sing to 432hz without instruments since their childhood – which was at a time when 432hz tuning was the standard.  Which means that just like the older European instruments, 432hz is their “native” tuning.

So I do believe the discomfort the older, more expeienced opera singers are experiencing with 440hz and 444hz tuning is real.
Younger opera singers who have never trained with 432hz tuning, obviously don’t have this problem, because their “native tuning” is 440hz – they were never taught to sing to 432hz in the first place, and many will no doubt experience nodules on their vocal chords and other vocal health problems at various times in their careers.  Which I believe, would not happen if they were singing at the natural 432hz tuning.

Of course this needs further research and investigation by those without any conflict of interest.

To read more about Pythagorean tuning – including history and origins, see this article on Wikipedia, which states that Pythagorean tuning is identical to Chinese traditional music:
https://en.wikipedia.org/wiki/Pythagorean_tuning