Concert pitch is the pitch reference to which a group of musical instruments are tuned for a performance. Concert pitch may vary from ensemble to ensemble, and has varied widely over time. The ISO defines international standard pitch as A440, setting 440 Hz as the frequency of the A above middle C. Frequencies of other notes are defined relative to this pitch.
The written pitches for transposing instruments do not match those of non-transposing instruments. For example, a written C on a B clarinet or trumpet sounds as a non-transposing instrument's B. The term "concert pitch" is used to refer to the pitch on a non-transposing instrument, to distinguish it from the transposing instrument's written note. The clarinet or trumpet's written C is thus referred to as "concert B".
Modern standard concert pitch
The A above middle C is often set at 440 Hz. Historically, this A has been tuned to a variety of different pitches.
History of pitch standards in Western music
Historically, various standards have been used to fix the pitch of notes at certain frequencies. Various systems of musical tuning have also been used to determine the relative frequency of notes in a scale.
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 semitones lower than that used for a domestic keyboard instrument in the same city.
Because of the way organs 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 = while a specimen from 1780 is pitched at A = about a quarter-tone lower. A tuning fork that belonged to Ludwig van Beethoven around 1800, now in the British Library, is pitched at A = , well over a half-tone higher.
Towards the end of the 18th century there was an overall tendency for the A above middle C to be in the range of to
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.
Pitch inflation
When instrumental music has risen in prominence (relative to vocal music), there has been a consistent tendency for pitch standards to rise. This led to reform efforts on at least two occasions. At the beginning of the 17th century, Michael Praetorius reported in his encyclopedic Syntagma musicum that pitch levels had become so high that singers were experiencing severe throat strain and lutenists and viol players were complaining of snapped strings. The standard voice ranges he cites show that the pitch level of his time, at least in the part of Germany where he lived, was at least a minor third higher than today's. Solutions to this problem were sporadic and local, but generally involved the establishment of separate standards for voice and organ () and for chamber ensembles (). Where the two were combined, as for example in a cantata, the singers and instrumentalists might use music written in different keys. This kept pitch inflation at bay for some two centuries.
Concert pitch rose further in the 19th century, evidenced by tuning forks of that era in France. The pipe organ tuning fork in Versailles Chapel from 1795 is 390 Hz, an 1810 Paris Opera tuning fork sounds at A = 423 Hz, an 1822 fork gives A = 432 Hz, and an 1855 fork gives A = 449 Hz. At La Scala in Milan the A above middle C rose as high as .