A440 (pitch standard)

A440 or A4 (also known as the Stuttgart pitch), which has a frequency of 440 Hz, is the musical note of A above middle C and serves as a general tuning standard for musical pitch.

The International Organization for Standardization classifies it as ISO 16. Before standardization on 440 Hz, other frequencies were standardized upon. Although not universally accepted, it serves as the audio frequency reference to calibrate acoustic equipment and to tune pianos, violins, and other musical instruments.

A440 Play piano  or Play violin .

History and use

Before standardization on 440 Hz, many countries and organizations followed the French standard since the 1860s of 435 Hz, which had also been the Austrian government's 1885 recommendation.[1] Johann Heinrich Scheibler recommended A440 as a standard in 1834 after inventing the "tonometer" to measure pitch,[2] and it was approved by the German Natural History Society the same year.[3]

The American music industry reached an informal standard of 440 Hz in 1926, and some began using it in instrument manufacturing.

In 1936 the American Standards Association recommended that the A above middle C be tuned to 440 Hz.[4] This standard was taken up by the International Organization for Standardization in 1955 (reaffirmed by them in 1975) as ISO 16.[5]

It is designated A4 in scientific pitch notation because it occurs in the octave that starts with the fourth C key on a standard 88-key piano keyboard. On MIDI, it is note 69.

Piano Frequencies
An 88-key piano, with the octaves numbered and Middle C (cyan) and A4 (yellow) highlighted.

A440 is widely used as concert pitch in the United Kingdom[6] and the United States.[7] In continental Europe the frequency of A4 commonly varies between 440 Hz and 444 Hz.[6] In the period instrument movement, a consensus has arisen around a modern baroque pitch of 415 Hz (with 440 Hz corresponding to A), baroque for some special church music (Chorton pitch) at 466 Hz (with 440 Hz corresponding to A), and classical pitch at 430 Hz.[8]

A440 is often used as a tuning reference in just intonation regardless of the fundamental note or key.

The US time and frequency station WWV broadcasts a 440 Hz signal at two minutes past every hour, with WWVH broadcasting the same tone at the first minute past every hour. This was added in 1936 to aid orchestras in tuning their instruments.[9]

See also


  1. ^ Karp, Theodore (1983). Dictionary of Music. Northwestern University Press. p. 406. ISBN 9780810106598.
  2. ^ Robert Thomas Beyer (1999). Sounds of our times: two hundred years of acoustics. Springer. p. 32. ISBN 978-0-387-98435-3.
  3. ^ Helmholtz, Hermann von (1863). Die Lehre von den Tonempfindungen als physiologische Grundlage für die Theorie der Musik, p.29. J. Vieweg. [ISBN unspecified].
  4. ^ Martin, George (2008). The Opera Companion. Hal Leonard Corporation. ISBN 978-1-57467-168-1.
  5. ^ ISO 16:1975 Acoustics – Standard tuning frequency (Standard musical pitch). International Organization for Standardization. 1975.
  6. ^ a b Nistl, Franz. "Europa E - SK". Klavierstimmung.
  7. ^ Nistl, Franz. "Afrika Amerika Asien Ozeanien". Klavierstimmung.
  8. ^ Oxford Composer Companion JS Bach, page 369–372. Oxford University Press, 1999
  9. ^ "History of WWV". Physical Measurement Laboratory, NIST. September 16, 2015.
440 (disambiguation)

440 may refer to:

440, the year

440 BC, the year

440 (number), the numberIt can also refer to:

The 440-yard dash, a track-and-field event

Area code 440, a telephone area code in the Cleveland, Ohio area

A440 (pitch standard), the frequency of the note A above middle C used in standard western music theory

440, the backup band for Dominican musician Juan Luis Guerra

Volvo 440/460, an automobile model

4-4-0, a type of steam locomotive


A440 or A-440 may refer to:

A440 (pitch standard)

A440 highway (Australia), a road in Victoria, Australia

Quebec Autoroute 440 (Laval)

Quebec Autoroute 440 (Quebec City)

C (musical note)

C (Italian, French: Do) is the first note of the C major scale, the third note of the A minor scale (the relative minor of C major), and the fourth note (F, A, B, C) of the Guidonian hand, commonly pitched around 261.63 Hz. The actual frequency has depended on historical pitch standards, and for transposing instruments a distinction is made between written and sounding or concert pitch.

In English the term Do is used interchangeably with C only by adherents of fixed-Do solfège; in the movable Do system Do refers to the tonic of the prevailing key.


A millisecond (from milli- and second; symbol: ms) is a thousandth (0.001 or 10−3 or 1/1000) of a second.A unit of 10 milliseconds may be called a centisecond, and one of 100 milliseconds a decisecond, but these names are rarely used.

To help compare orders of magnitude of different times, this page lists times between 10−3 seconds and 100 seconds (1 millisecond and one second). See also times of other orders of magnitude.

Piano tuning

Piano tuning is the act of making minute adjustments to the tensions of the strings of an acoustic piano to properly align the intervals between their tones so that the instrument is in tune. The meaning of the term 'in tune', in the context of piano tuning, is not simply a particular fixed set of pitches. Fine piano tuning requires an assessment of the vibration interaction among notes, which is different for every piano, thus in practice requiring slightly different pitches from any theoretical standard. Pianos are usually tuned to a modified version of the system called equal temperament (see: Piano key frequencies, for the theoretical piano tuning).

In all systems of tuning, every pitch may be derived from its relationship to a chosen fixed pitch, which is usually A440, the note A above middle C (261.626 Hz).

Piano tuning is done by a wide range of independent piano technicians, piano rebuilders, piano-store technical personnel, and hobbyists. Professional training and certification is available from organizations or guilds, such as the Piano Technicians Guild. Many piano manufacturers recommend that pianos be tuned twice a year.

Scientific pitch

Scientific pitch, also known as philosophical pitch, Sauveur pitch or Verdi tuning, is an absolute concert pitch standard which is based on middle C (C4) being set to 256 Hz rather than 261.62 Hz, making it approximately 37.6 cents lower than the common A440 pitch standard. It was first proposed in 1713 by French physicist Joseph Sauveur, promoted briefly by Italian composer Giuseppe Verdi in the 19th century, then advocated by the Schiller Institute beginning in the 1980s.

Scientific pitch is not used by concert orchestras but is still sometimes favored in scientific writings for the convenience of all the octaves of C being an exact round number in the binary system when expressed in hertz (symbol Hz). The octaves of C remain a whole number in Hz all the way down to 1 Hz in both binary and decimal counting systems. Instead of A above middle C (A4) being set to the widely used standard of 440 Hz, scientific pitch assigns it a frequency of 430.54 Hz.Note that 256 being a power of 2, only octaves (factor 2) and, in just tuning, higher-pitched perfect fifths (factor 3/2) of the scientific pitch standard will have a frequency of a convenient integer value. With a Verdi pitch standard of 432 = 2⁴ × 3³, in just tuning all octaves (factor 2), perfect fourths (factor 4/3) and fifths (factor 3/2) will have pitch frequencies of integer numbers, but not the major thirds (factor 5/4) nor major sixths (factor 5/3) which have a prime factor 5 in their ratios. However scientific tuning implies an equal temperament tuning where the frequency ratio between each half tone in the scale is the same, being the 12th root of 2 (a factor of ≈ 1.059463), which is not a rational number: therefore in scientific pitch only the octaves of C have a frequency of a whole number in Hertz.

Tom Wall (guitarist)

Tom Wall is an American singer-songwriter, musician and activist from Grand Rapids, Michigan. Wall is known for being the lead singer, guitarist, and bandleader of the progressive rock band Cosmic Knot, and for his collaborations with Muruga Booker.

Wall prefers to play in alternate tunings, such as Verdi tuning (A=432 hz) as opposed to the A440 (pitch standard) in the hopes of promoting a healing and overall calming effect on listeners.Wall began playing guitar as a teenager, and was soon writing songs and performing in local bands. In 2013, he began playing with Hannah Rose Graves and the GravesTones. In 2015 Wall played guitar on the Skee-Town Stylee album All You Want.In 2015, he formed the band Cosmic Knot and that same year they headlined at the annual Wish You Were Here festival in Fremont, Michigan, where he also jammed with P-Funk All Stars members Muruga Booker and Tony "Strat" Thomas. Tom Wall and Cosmic Knot headlined the 2016 and 2017 Wish You Were Here festivals as well.Booker and Wall have collaborated on several musical projects together, including The Muruga Band "Mystic World", which was nominated for a 2015 Detroit Music Award, and Muruga Blues Band "Fool's Blues", which was nominated for a 2016 Detroit Music Award.In 2016 Wall also recorded a song with Muruga Booker and Grammy Award winning harmonica player Peter "Madcat" Ruth, written by and featuring his father Tom "T" Wall, called "Deer Camp", and was also nominated for a Detroit Music Award.In 2016, Cosmic Knot recorded their debut album called Inner Space at Third Coast Recording Studio, in Grand Haven, Michigan. Inner Space was released in August 2017, with all of the songs having been written by Wall. In 2017, even before their debut album was released, Cosmic Knot won the Best Song contest at Grand Haven’s Walk the Beat festival for their song "Like a Gypsy".At the 2017 Hash Bash in Ann Arbor, Michigan, Wall performed the Star Spangled Banner on guitar, to start the event, and afterwards Cosmic Knot performed a full set for over 10,000 people.

ISO standards by standard number
See also

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