John Carlos BaezSome people claim that our current tuning system, where the note A is 440 Hz (cycles per second), is bad for your health. They prefer A=432 Hz. But more interesting to me is that the A=440 standard arose because 439 is a prime number!
In early Europe tuning wasn't standardized, and the pitch of organs ranged from at least A=337 to A=567. As musicians started traveling more, the desire for standardization increased. Handel expressed a fondness for A=423, Mozart for A=422. Later there was a kind of arms race toward higher and higher pitches, going up to A=450.
This became tough on singer's voices - so in 1859, the French made A=435 the law in that country. At the urging of some opera singers, this standard was adopted for a while in other parts of Europe.
In 1896, London’s Royal Philharmonic Society got around the A=435 rule in a funny way. They argued that when the French set the A=435 standard, they had not specified a frequency, but had specified 59° F as the room temperature under which a particular oboe played A at 435 cycles per second. They argued that the same instrument at normal room temperature would play an A at about 439 Hz. So they took *that* as the standard!
Later, in 1939, the BBC wanted to play a standard tuning note before broadcasting concerts. Their note was derived from an oscillator controlled by a piezoelectric crystal that vibrated with a frequency of one million hertz. This was reduced to a frequency of 1,000 hertz by electronic dividers. Then the frequency was multiplied by 11 and divided by 25 giving a frequency of 440 Hz. Since 439 is prime, it was inconvenient to create a frequency of 439 Hz this way.
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