Editing Concert pitch (section)

===Pre-19th century===
Until the 19th century there was no coordinated effort to standardize musical pitch, and the levels across Europe varied widely. Pitches varied over time, from place to place, and even within the same city. The pitch used for an English cathedral organ in the 17th century, for example, could be as much as five [[semitone]]s lower than that used for a domestic [[keyboard instrument]] in the same city.

Because of the way [[organ (music)|organ]]s were tuned, the pitch of a single organ could even vary over time. Generally, the end of an organ pipe would be tapped with a cone tuning tool to curve it inwards to raise the pitch, or outwards to lower it.

The [[tuning fork]] was invented in 1711, enabling the calibration of pitch, although there was still variation. For example, a 1740 tuning fork associated with [[Handel]] is pitched at A&nbsp;=&nbsp;{{Audio-nohelp|Tone-422.5-Hz.ogg|422.5&nbsp;Hz,}} while a specimen from 1780 is pitched at A&nbsp;=&nbsp;{{Audio-nohelp|Tone 409Hz.ogg|409&nbsp;Hz,}} about a quarter-tone lower.<ref>{{Cite journal |last=Mendel |first=Arthur |date=1978 |title=Pitch in Western Music since 1500. A Re-Examination |url=https://www.jstor.org/stable/932288 |journal=Acta Musicologica |volume=50 |issue=1/2 |pages=82 |doi=10.2307/932288 |issn=0001-6241 |quote=Still another fork has acquired what may be more authority than it deserves. Pascal Taskin, harpsichord-maker and tuner to the French Court, owned in 1783 a fork that had been tuned to the oboe of Antoine Sallentin, of the Opera and Chapelle du Roi. Whether Sallentin played the same oboe both in the Opera and in the Chapelle is not known-nor whether Taskin tuned any or all of his instruments to this fork, whose pitch was a1 = 409.|url-access=subscription }}</ref> A tuning fork that belonged to [[Ludwig van Beethoven]] around 1800, now in the [[British Library]], is pitched at A&nbsp;=&nbsp;{{Audio-nohelp|Tone 455.4Hz.ogg|455.4&nbsp;Hz}}, well over a half-tone higher.<ref name="Beethoven">{{cite web|title=Beethoven's tuning fork|url=http://blogs.bl.uk/music/2017/03/beethovens-tuning-fork.html?_ga=2.111538244.1976350515.1539182456-1763597418.1539182456|publisher=[[British Library]]|date=28 March 2017}}</ref>

Towards the end of the 18th century there was an overall tendency for the A above middle C to be in the range of {{Audio-nohelp|Tone 400Hz.ogg|400}} to {{Audio-nohelp|Tone 450Hz.ogg|450&nbsp;Hz.}}

The frequencies referred to here are based on modern measurements and would not have been precisely known to musicians of the day. Although [[Mersenne]] had made a rough determination of sound frequencies as early as the 17th century, such measurements did not become scientifically accurate until the 19th century, beginning with the work of German physicist [[Johann Scheibler]] in the 1830s. Frequency is measured in [[cycles per second]] (CPS). During the 20th century this term was gradually replaced by ''[[hertz]]'' (Hz) in honor of [[Heinrich Hertz]].