Blog » How did A4=440Hz became the standard?

Reading Time: 5 minutesOctober 19, 2013


Before concert pitch A4=440Hz became the tuning and manufacturing standard for instruments, there was no (International) Standard Pitch. For centuries it was thought that sound was so ephemeral that any attempt to capture it — to hold a ruler against it — would be a fruitless exercise. In fact, until the 17th century natural philosophers thought it absolutely illogical to make any attempt to quantify it or even theorize about its measurement.

The first “steps” in frequency analysis were made in March 1676 by British scientist Robert HookeIt wasn’t until 1834 that Frenchman Félix Savart who build a machine, using a mechanical tachometer and for the first time demonstrated that specific tones were associated with specific frequencies. It wasn’t up to the “Acoustic Era” (approx. 1870-1925) when scientists could start measuring sound frequency accurately, using a combination of tools, such as the Microphone, the Galvanometer, a vacuum tube and the Thermophone. 

For more detailed historical info read the Roel’s World article “Audio Frequency – a short historical time-line“.

What I like to make clear with this, is that until 1676 (as far as historical documentation goes) no one had measured and analyzed the exact tone frequencies. A “Concert Pitch” did not really “exist” as such. Musicians would tune “by ear”, using one of the instruments of a group as reference, usually an instrument that was least effected by pitch change. In those days a wind instrument was the most likely choice to be used as reference.

Claims of exact Concert Pitches used before 1676 (as for example with the claim that 432Hz was used as Concert Pitch in “ancient times”) seem thus rather “questionable” to me.

We can find the following historical references concerning 440Hz as Concert Pitch, predating the standardization if this Concert Pitch:

  • 1834 – The Stuttgart Conference (a Congress of Physicists – “Deutsche Naturforscherversammlung”) adopts Scheibler’s recommendation for A4=440Hz as the standard pitch (the Stuttgard or “Scheibler pitch”), based on Johann Scheibler‘s studies with his Tonometer. It consisted of 52 forks tuned from A 219 2/3 to A 439 1/2 at 69 degrees Fahrenheit. The device and his amazingly accurate method of measuring beats were described in Scheibler’s book “The Physical and Musical Tonometer”.
  • It is not unlikely that the “Streicher Piano Company” adopted Scheibler’s recommendation for A=440 shortly after the Stuttgart Congress.
  • 1836-1839: A= 441, Paris. Opera pianos. Tuning fork owned by M. Leibner who tuned the pianos of the opera at the pitch of the orchestra. In 1849 it agreed precisely with the oboe of M. Vorroust.
  • Date unknown. A=440.5, Paris. Opera. Fork said to have been adjusted by Pleyel.
  • 1845 A=439.9, Turin Italy. Tuning fork.
  • 1859 A=441, Dresden. Opera. Tuning fork sent to the French Commission by Kapellmeister Reissiger, who wrote: The great elevation of the diapason destroys and effaces the effect and character of ancient music, of the masterpieces of Mozart, Gluck and Beethoven.
  • In 1862 German physician and physicist Hermann Ludwig Ferdinand von Helmholtz, publisched his work the Sensations of Tone as a Physiological Basis for the Theory of Music. In this work Hermann Helmholtz refers to A at 440Hz several times.
  • In 1880 Alexander Ellis wrote an important essay “The History of Musical Pitch” for the Society of Arts in London. Ellis cites early research on the measurement and history of musical pitch in the work of the German physicist Johann Heinrich Scheibler (1777-1837). Ellis’ research suggests that there was a connection between Scheibler in Stuttgart and the piano maker Johann Baptist Streicher in Vienna. A tuning fork with the name “Streicher” written in ink on one of the prongs and measuring A=443.2 was found in Scheibler’s collection of forks after his death.
  • 1896 – Britain’s Royal Philharmonic starts using A4=439Hz.
  • In 1926 the American music industry reached an informal standard of 440 Hz, many did use it already before, now pretty much all were using it in instrument manufacturing. (No supporting documentation found).
  • 1938 or 1939 – The majority of attending members at an international conference in London supports A4=440Hz. (Note: no supporting documentation found). This conference is often mentioned in the “Goebbels / Nazi Germany 440Hz myth“.
  • 1955 – International Organization for Standardization adopts A4=440Hz. (Note: no supporting documentation found).
  • 1975 – The International Organization for Standardization affirms the International Concert Pitch A4=440Hz  under  ISO 16:1975.


This pitch was commonly used during the “Baroque period” (1600-1760). 415Hz is 101 cents or 1.01 semitone below the present 440Hz standard. With other words, Concert Pitch 440Hz is 415Hz transposed a semitone up. So, the tone frequency of 440Hz likely “sounded” already for approximately 400 years ago

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To be able to place the history of ISO in historical perspective, I have decided to create a “timeline”, with information about various National (BSI – England, ASA -USA, Germany) and International standardization organizations and institutes – such as the ISO (International Standard Organisation).

Not all information below is directly related to the standardization of the Concert Pitch itself (the events that suggested, supported and/or implemented the standardization of concert pitch A4=440Hz I have marked with green).

  • 22 January 1901 – forming of a committee to consider standardizing iron and steel sections. 26 April 1901, the first meeting of the Engineering Standards Committee (ESC). 1903 – creation and registration of the British Standard Mark (Kitemark).
  • 1916 – the American Institute of Electrical Engineers (now IEEE) invited the American Society of Mechanical Engineers (ASME), the American Society of Civil Engineers (ASCE), the American Institute of Mining and Metallurgical Engineers (AIME) and the American Society for Testing Materials (now ASTM International) to join in establishing an impartial national body to coordinate standards development, approve national consensus standards, and halt user confusion on acceptability. These five organizations, who were themselves core members of the United Engineering Society (UES), subsequently invited the U.S. Departments of War, Navy and Commerce to join them as founders.
  • 1918 – The Engineering Standards Committee  (ESC) changed its name to British Engineering Standards Association (BESA).
  • During the 1920sESC standardization spread to Canada, Australia, South Africa and New Zealand. Interest was also developing in the USA and Germany.
  • The AESC hosted in 1926 (10.05 & 11.05) a conference that created the International Standards Association (ISA), an organization that would remain active until World War II and that would eventually become the International Organization for Standardization (ISO).
  • In 1926 the American music industry reached an informal standard of 440 Hz, and used it for instrument manufacturing. (Note: no online documentation found to support this.)
  • On 22 April 1929, the British Engineering Standards Association (BESA) was granted a Royal Charter.
  • As its responsibilities and activities evolved, AESC outgrew its committee stature and structure. In 1928, it was reorganized and renamed the American Standards Association (ASA).
  • 1928 – a group of some 40 scientists and engineers interested in acoustics, met on 27 December 1928 at the Bell Telephone Laboratories in New York, NY, to consider forming a scientific society (Acoustical Society of America).
  • The Acoustical Society of America was formally organized and held its first meeting 10-11 May 1929.
  • A supplemental Charter was granted in 1931 changing the name British Engineering Standards Association (BESA) to The British Standards Institution (BSI).
  • In 1931, the U.S. National Committee of the IEC became affiliated with ASA.
  • In 1931 the Acoustical Society of America joined with three other scientific societies to form the American Institute of Physics.
  • 15-16 May 1939: official meetings of the Acoustical Society of America.
  • 02-04 November 1939: official meetings of the Acoustical Society of America.
  • 1939 – The majority of attending members at an international conference in London supports A4=440Hz. (Note: no online documentation found to support this.)
  • 1946 saw the first ever Commonwealth Standards Conference, held in London and organized by BSI, which led to the establishment of the International Organization for Standardization (ISO).
  • 1947 – The International Standard Organization was founded.
  • 1955 – International Organization for Standardization adopts A4=440Hz. (Note: no online documentation found to support this.)
  • 1975 – The International Organization for Standardization affirms the International Concert Pitch A4=440Hz under  ISO 16:1975.


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