The HistoryPythagoras, the ancient Greek all-round smart person, was attributed a tuning with a reference of 432hz for an A now simply called Pythagorean Tuning. It is/was based on a tuning ratio of 3:2, whereas most Western musical tuning is based on a ratio of 1:1 (not really sure what means, but its an easily researchable topic). Complicated tuning ratios and mathematics aside, the traditional 440hz scale looks like this (with the 432hz scale mentioned further down).
The sound of the scale reportedly makes the sound of perfect 5ths sound harmonically rich and "smooth" while 3rds (particularly major and minor), which have relatively complex tuning ratios of 81:64 and 32:27 respectively, sound dissonant. To counter-act this problem with certain intervals, the Pythagorean Scale idea came along. A Pythagorean Scale is simply put, any scale that is comprised entirely of perfect 5ths and octaves. An example would be that old chestnut, C Major. The dissonant intervals that arose from the Pythagorean tuning are known as "wolf intervals" due to their sound (presumably, it sounds like a wolf).
This tuning and scale were thought to have been wide-spread in the ancient world, but now are both rarely heard about (bad pun) in modern music, mostly due to that wolf interval and modern music generally being more harmonically exploratory (in Pythagorean tuning, this approach would've caused the wolf interval to show up more).
The "Experiment"A few months ago, I tested out the 432hz reference on my guitar, tuned to D standard and occasionally Drop C. I've been using this tuning up until right just now where I decided to try 440 again to see if there'd be any discernible difference. To test it out during recording, I did a cover of "Jane Doe" by Converge a month or so after I started to use the tuning. (Shameless self-promoting linkage).
But turning back towards the point, overall I noticed a difference in the way things sounded: Individual notes played in a scale sounded relatively indifferent to each other, while the higher up the fretboard I played, the more noticeable a slight discrepancy in notation became, until the point where I was confused over if my intonation was out of whack or if it was just the tuning. I also noticed that an open A# perfect 5th power chord (as if there's any other type of power chord) sounded "clean", fully tuned and warmer than an open A#maj7 barre chord, which sounded slightly out of tune but with a lot of "colour" to it, if that makes sense (people with synesthesia will know more about that). In comparison, another guitar tuned to 440 in E standard playing the same chords sounded flatter and duller overall, but with much less underlying dissonance, having more consonance. Even when tuning the strings to as close as 432 as possible, the dissonance was still there, and it changed the way I started writing riffs, where death metallish dissonance actually sounded nicer than playing melodies that used diatonic chord patterns.
Another thing I sort of stumbled on, was that the guy who initially told me about this, had recently "converted" the entire "Periphery II" album from (what was apparently) 440hz to 432hz. All it needed was some editing in Audacity to change it. I heard the song "Racecar" (actually from the first album) in 440 then 432. The overall sound difference was noticeable, the 432 version sounding warmer, clearer and instantly sounded more listenable (given my opinion on Periphery, that's something, right?) but the 440 version felt tighter, with more aggressive energy.
You can actually try this experiment yourself (very thankfully, for free as free can be): Download Audacity, which is freeware, follow these steps in this video and discern whether or not there's any difference.
The Crazy PartsOkay, so 432hz doesn't seem to be a big deal up until you understand why its suddenly been cropping up in places: Crazy conspiracy theories.
According to the weird side of the internet, a torrent of reliable and factual information (haha, yeah right), during World War 2, a certain Mr Goebbels (crazy Nazi propaganda minister) was thinking of more and more ideas that allowed for complete superiority over the general populace (as if murdering people wasn't enough) when he stumbled upon the idea of changing standardized musical tuning to something that would cause stress or anxiety in casual listeners, hence the change to 440. He pushed this idea heavily but it was ultimately rejected once the war actually started. Then (internet reliability still in effect), the NWO (yes, really) implemented the change seemingly overnight because they felt like it, and now the supposed reason that the modern lifestyle is full of stress and conformity is because of a slight uptuning in instrumentation across popular music. It's now safe to take off the tin foil hat.
Crazy Nazi theories aside (without a mention of Hitler, until just now), there might be some weight to the "tunings make you feel different" idea. According to another internet page (which I lost the link to), 432hz is tied with the Music of the Spheres, where planets and celestial bodies (another name for planets, I think) generate their own frequency. Its not entirely ignorable: Science previously discovered that the static on your TV is actually the sound and energy of dying stars, and that anything producing energy actually produces some kind of sound, whether loud or quiet (that includes atoms vibrating). This possibly means that, given our knack for living on earth, we're "tuned" to the cosmic hum of the planets rotation (kind of a cool idea actually). And for some reason, this is believed to be in the tuning of 432hz.
Maybe we've found why 3 is the magic number. Here are some comparative frequencies of other notes tuned with a reference of 432hz (these are the few notes I found the frequencies of):
A = 432hz
D = 288hz
E = 324hz
G = 384hz
The main thing to take note is, they're (almost) whole numbers, and are wholly divisible by 3. Apparently that means something, not entirely sure what myself, but according to some scientist (John Stuart Reid), after developing a "Cymascope" (after cymatics) which is essentially a really colourful oscilloscope or a more interesting variation of cornstarch-in-a-subwoofer, made a note that any notes tuned to 432hz: "432 Hertz pops out as a triangle, every time we image it. We thought there was something wrong with the CymaScope - but after trying for more than an hour we concluded that the number 3 was somehow universally connected to 432 Hertz." Pretty interesting stuff. However, the same site startes delving into "chakra" and "third eyes" and blurring supposedly real science with stoner's dreams and all that, maybe with some grain of truth to it, but I couldn't test it myself.