A440



Under the A440 pitch standard, the musical note A above middle C corresponds to exactly 440 Hz (440 vibrations per second), and all other notes are based on fixed intervals from this note (for instance, the "A" below middle C is 220 Hz, and the E above middle C is, in twelve-tone equal temperament, approximately 329.628 Hz, but not quite 330 Hz, which is the price of abandoning just intonation).

A440 has been used here and there since the mid-19th century. The ISO adopted it as a standard in 1955, and affirmed it again in 1975, but A440 is more of a loose consensus than a legal requirement. Many musicians use it, and many others use something else - for example, A443 is commonly used by orchestras in some European countries, such as Austria and Germany. A few rock and pop tracks, such as "Baba O'Riley" by The Who or "The Battle of Evermore" by Led Zeppelin, are known for being tuned slightly sharp or flat, requiring a guitarist to tune to a different standard to play along. Pitch standard is not a natural law, nor is it a law of the land.

Some sensitive souls are deeply concerned that humanity is driving a wedge between ourselves and our true cosmic nature when we tune our music to this convenient frequency.

"A" little history
Before A440 became common, musicians tuned instruments to a wide variety of pitch standards, including A432, A435, A444, C256, C528, or A417 (and some musicians still use these tunings today.) The first attempt to standardize tuning was Austria's recommendation of A435, and in 1936, the USA standardized A440. Since 1955, the International Organization of Standardization has implemented A440 as the global standard for pitch.

The majority of American, Australian, and European musicians use A440, and the standard has also spread to Asia and Africa as their music becomes more Western-influenced. For the most part, an A is an A, whether it's on a Steinway in New York, Bosendorfer in Germany, or Yamaha in Tokyo. However, some musicians still tune their instruments (and voices) to whatever they like best, or according to the preference of their musical director. For example, many groups playing Baroque or Early music, particularly on historical instruments, may choose to play at a pitch common in the time and place the music they are playing was composed in. If a group includes a fixed-pitch instrument such as a piano, xylophone, or accordion, the group may tune to that. If the instrument is digital (i.e., most modern keyboards), re-tuning can be as easy as typing in the correct value of A.

Often 432 Hz is claimed as the frequency of the universe, but in fact it is a so called composite number (the opposite of a prime number). By choosing this number it is easy to calculate frequencies of other tones in musical scales. Just intoned C becomes 264 or 528 with 440 for instance, since this interval is a minor third that is 6/5 of the fundamental frequency. 432 is a handy number when you don't have a calculator, therefore it appears in many old music theoretical books. (Keep in mind that 440 is also a composite number.)

The actual there there
To be clear: There is one area where A440/A432 is actually a real thing: written music composed before 1900, and especially before 1850. Since the tuning was so variable, a single piece of music could sound wildly different when played with different A tunings. Some pieces sound better (or "better" in scare quotes) with different A tunings, and in pieces where singing is a consideration (for example, opera), can make the piece much easier or harder to actually perform.

But that's where the scientific and rational debate ends, and we enter the realm of...

Conspiracy theories and woo
Crank websites and books have stated many wild and pseudoscientific claims about A440.


 * It disagrees with the "vibratory nature of the universe," whatever that means.
 * It leads to stress, aggression, and antisocial behavior in humans. While a difference in intonation between instruments heard simultaneously will usually annoy someone, asserting a natural psychological preference for any particular absolute reference is just plain nonsensical.
 * It was created by Nazi propagandists to brainwash people.
 * Other standards (like the so-called "solfeggio frequencies" ) align better with DNA, phi, light, time, gravity, and other things that have nothing to do with sound.

Some websites, following the lead of figures such as Leonard Horowitz, even claim that non-440 standards, usually A432 or C528 (which is roughly A444), can heal the body or repair DNA.

There is even a service, called 528records, that sells music that has been converted to C528. That this conversion is easily within reach of a child with some basic sound editing tools and a calculator is apparently ignored.

The bottom line
For most people, pitch is relative. When listening to music, we generally don't perceive actual pitches; we perceive the intervals between them. A few people with absolute (or "perfect") pitch may be able to tell the difference between 440 hertz and 444 hertz tones heard in isolation, but when listening to music on an everyday basis, even they may not notice or care. Some may even prefer A440, since they grew up with it. Perfect pitch still relies on relative pitch and culturally-determined pitch standards, not some absolute genetic reference. Woo-meisters, pushing a 440 conspiracy, have misinformed people about how pitch works, and have scammed whoever paid to have music converted to "solfeggio frequencies."