Its a complicated story indeed...
One of the first references to the tuning of middle C at 256 oscillations per second was (probably) made by a contemporary of J.S. Bach.
It was at that time that precise technical methods were developed making it possible to determine the exact pitch of a given note in cycles per second. The first person said to have accomplished this was Joseph Sauveur (1653-1716). He measured the pitches of organ pipes and vibrating strings, and defined the C of the musical scale at 256 cycles per second.
Nevertheless, in the 1700s 392Hz to 415Hz (Baroque Pitch) was commonly used for Concert A, particularly in France and often had to do with whatever the local church organ was tuned to.
In Germany, Mozart tuned at C=256, his A was in the range of A=427-430. German instruments of the period 1780-1827, and even replicas of those instruments, can only be tuned at A=430.
The 1800s had started with 420-425 Hz (Early Music musicians call this "Low Pitch").
This increased to around 430Hz later in the century and remained there into the 20th century (some called it "Philosophical pitch" referring to its connection to scientific thought at the time).
The first "troublemaker"
was Czar Alexander of Russia, at a Viennese congress in 1815, he called for a "brighter" sound, and so all the crowned heads of Europe began doing the same(!).
Despite protests from musicians that "Their Majesties" did not understand that new pitches often demanded the purchase of expensive new instruments (which first had to be designed!), composers Liszt and son-in law Wagner, lobbied for the pitch to be raised. Wagner even had instruments made for A=440Hz and above.
By the mid-1800s, pitches were varying from A=420 to A=460. The result was total confusion
.
So by the 3rd quarter of the 19th century, the French government, advised by Italian opera composer Rossini (who was "Inspector of Voices" in Paris), called for the first standardization of the pitch in modern times.
France consequently passed a law in 1859 establishing A at 435Hz, prompting Giuseppe Verdi (Joe Green
to grumble "we call A in Rome, what is B-flat in Paris" and attempted to raise the Italian standard to 432Hz. This was thrown out at a conference in Austria in 1885 following protests by the British.
To add to the chaos, Heinrich von Helmholtz's written work on acoustics around this time refers to C=256Hz while the French, the Americans (notably the New York Met), and many orchestras on both sides of the pond, continued to tune A between 432Hz & 435Hz, until the advent of the Second World War.
Then in 1939 Joseph Goebbels (The Nazi propagandist) attempted to establish a single internationally recognized pitch - A=440Hz - at a conference in London (notably excluding France from the group of invited nations), the Germans were developing tape recording were also using a 440Hz test-tone on radio, so they were eager to standardize. This failed due to the collapse of Anglo-German relations shortly after as war broke out.
In fact into the 1940s, all Western text books on physics, sound, and music took as a given the physical pitch or scientific pitch (known earlier as "Philosophical pitch") of C=256Hz.
The next attempt at laying down a universal pitch standard was in 1953 at a meeting of the International Standardizing Organization in London, the aim was to establish A at 440Hz.
This was passed but ignored by a significant number of musicians (who weren't invited this time either
!).
The French then accused the British instrument makers of catering to the burgeoning U.S. jazz trade, which tuned at A=440 and above bemoaning the fact that trained classical orchestras would be dependant on what "Jazz players" were dictating.
A subsequent referendum among thousands of French musicians voted overwhelmingly to remain at A=432Hz.
The last attempt to standardize pitch was in 1971 when the European Economic Community (EEC) passed a "recommendation" to fix international pitch at 440Hz. The world blinked and ignored it.
As you can see, its still not decided
In fact Highland bagpipers pitch (officially A=476Hz) is currently increasing at 1Hz every year, the reason being that people's perception of being sharp seems to suggest "brighter" and brighter soon becomes "better", which is a big advantage among competing pipe bands at the numerous competitions every year
.
At last count it was at 480Hz
!
Many pipers use our V-SAM tuners which top out at A=490Hz, so I tell them they have 10 years before the tuner runs out of steam
.
So to end this sad story here are the World Hz charts:
Scottish Bagpipers 480Hz
Indian Shrutis 444Hz
French Flautists 442Hz
American Country/Jazz/Rock/Blues 440Hz
Early Music lovers worldwide 392Hz/415Hz/430Hz
Don't forget that the temperament wars are a whole separate subject.........
Last but not least, I had a call from Stevie Wonder's people yesterday, Stevie has decided to go to 442Hz and they were looking for a tuner to tune everything up (including that old Hohner Clavinet he played on "Superstition").
I hope this wasn't too long winded,
Best regards,
John Norris
Right or wrong, I was always told from 1948 until now the 440Hz is Standard~Pitch and 442Hz is Concert~Pitch. 
