A440 (pitch standard)

{{short description|Pitch standard}} {{Image frame |content = <score sound="1"> { \hide Staff.TimeSignature \set Staff.midiInstrument = #"grand piano" a'1 \set Staff.midiInstrument = #"violin" a'1 } </score> |width=|caption = A440, piano and violin }}

'''A440''' (also known as '''Stuttgart pitch'''<ref>{{cite book |url=https://books.google.com/books?id=TMdf1SioFk4C&pg=PA679 |first=Willi |last=Apel |author-link=Willi Apel |date=1969 |title=Harvard Dictionary of Music |publisher=Harvard University Press |isbn=9780674375017 |via=Google Books |access-date=2023-01-09}}</ref>) is the musical pitch corresponding to an audio frequency of 440 Hz, which serves as a tuning standard for the musical note of A above middle C, or '''A4''' in scientific pitch notation. It is standardized by the International Organization for Standardization as '''ISO 16'''. While other frequencies have been (and occasionally still are) used to tune the first A above middle C, A440 is now commonly used as a reference frequency to calibrate acoustic equipment and to tune pianos, violins, and other musical instruments.

==History and use== Before standardization to 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.<ref>{{cite book |title=Dictionary of Music |last=Karp |first=Theodore |publisher=Northwestern University Press |year= 1983 |isbn=9780810106598 |url={{google books |id=G3bHp9WXRQAC |page=406 |plainurl=yes}} |page=406 |via=Google Books |access-date=2023-01-09}}</ref> Johann Heinrich Scheibler recommended A440 as a standard in 1834 after inventing the "tonometer" to measure pitch,<ref>{{cite book |title=Sounds of our times: two hundred years of acoustics |author=Robert Thomas Beyer |publisher=Springer |year=1999 |isbn=978-0-387-98435-3 |page=32 |url=https://books.google.com/books?id=kebDOljfX7oC&q=Johann+Scheibler&pg=PA32 |via=Google Books |access-date=2023-01-09}}</ref> and it was approved by the Society of German Natural Scientists and Physicians at a meeting in Stuttgart the same year.<ref>{{cite book |author-link=Hermann von Helmholtz |last=von Helmholtz |first=Hermann |year=1863 |title=Die Lehre von den Tonempfindungen als physiologische Grundlage für die Theorie der Musik |trans-title=The Study of the Sensations of Tone as a Physiological Foundation for the Theory of Music ''(alt:'' The Sensation of Tones'')'' |lang=de |page=29 |publisher=J. Vieweg |via=Google Books |url=https://books.google.com/books?id=siRDAAAAcAAJ&q=Scheibler&pg=PR3 |postscript=, |access-date=2023-01-09}} (pre-ISBN); see article on book ''Sensations of Tone''.</ref>

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.<ref>{{cite book |title=The Opera Companion |first=George |last=Martin |publisher=Hal Leonard Corporation |year=2008 |isbn=978-1-57467-168-1 |url={{google books |id=MjTLYqOoi3kC |page=92 |keywords=440-cps 1936 |plainurl=yes}} |via=Google Books |access-date=2023-01-09}}</ref>

In 1937 Sir James Swinburne, an electrical engineer and avid amateur musician, delivered a lecture to the Royal Musical Association on "The Ideal Scale," discussing the possibility of tuning a scale to pure ratios and adjusting these ratios to maintain consonance across different keys. The following year, Swinburne represented the Musical Association at a preliminary conference to determine the British stance on concert pitch. British piano tuners had adopted A439 as the standard in 1899, but Swinburne pointed out that 439 was a prime number, whereas 440 could be more easily factored and electronically synthesized. In May of 1939, delegates from France, Germany, The Netherlands, Italy, and England convened at Broadcasting House in London, the headquarters of the BBC, to address the issue of concert pitch. Representatives from Switzerland and the United States participated via mail. The other European delegates concurred with Swinburne's position and agreed to a standard of A440.<ref>{{Cite web |title=A brief history of the establishment of international standard pitch a equals 440 hertz, Lynn Cavanagh|url=https://www.wam.hr/sadrzaj/us/Cavanagh_440Hz.pdf |access-date=2026-01-27}}</ref>

This standard was taken up by the International Organization for Standardization in 1955 as Recommendation R 16,<ref>{{Cite web |title=ISO 16:1975(en) Acoustics — Standard tuning frequency (Standard musical pitch) |url=https://www.iso.org/obp/ui/#iso:std:iso:16:ed-1:v1:en |access-date=2022-03-09 |website=International Organization for Standardization}}</ref> before being formalised in 1975 as '''ISO 16'''.<ref>{{cite book |title=ISO 16:1975 Acoustics – Standard tuning frequency (Standard musical pitch) |publisher=International Organization for Standardization |year=1975 |url=http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=3601 |access-date=2023-01-09}}</ref>

The A440 standard is not universally adhered to. Early-music ensembles continue to use older, lower pitch levels. Leonard Bernstein often tuned the New York Philharmonic to A442, leading to complaints from the piano tuners' union, although he claimed both the New York and Boston orchestras had used this higher pitch for years.

==Modern practices== [[File:Piano Frequencies.svg|frame|alt=Piano Keyboard|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<ref name="Nistl-page3">{{cite web | first= Franz | last= Nistl | url= http://members.aon.at/fnistl/page3.html | title= Europa E - SK | work= Klavierstimmung}} </ref> and the United States.<ref>{{cite web | first= Franz | last= Nistl | url= http://members.aon.at/fnistl/page4.html | title= Afrika Amerika Asien Ozeanien | work= Klavierstimmung}}</ref> In continental Europe the frequency of A4 commonly varies between 440 Hz and 444 Hz.<ref name="Nistl-page3"/> In the period instrument movement, a consensus has arisen around a modern ''baroque pitch'' of 415 Hz (with 440 Hz corresponding to A{{music|sharp}}), a 'baroque' pitch for some special church music (in particular, some German church music, e.g. the pre-Leipzig period cantatas of Bach)<ref name=OCCJSB>Oxford Composer Companion JS Bach, pp. 369–372. Oxford University Press, 1999</ref> known as ''Chorton pitch'' at 466 Hz (with 440 Hz corresponding to A{{music|flat}}), and ''classical pitch'' at 427–430 Hz.<ref name=OCCJSB/>

{{Listen|filename=Sine wave 440.ogg|title=A440|description=5 seconds of a pure tone at 440 Hz|format=Ogg}}

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.<ref>{{cite web | title= History of WWV | publisher= Physical Measurement Laboratory, NIST | date= September 16, 2015 | url= https://www.nist.gov/pml/div688/grp40/wwv-history.cfm |access-date=2023-01-09}}</ref>

{{Sequence | prev = ISO 15 | list = Lists of ISOs | curr = ISO 16 | next = ISO 17 }}

== References == <references/>

==Further reading== * {{cite book |last=Gribenski |first=Fanny |title=Tuning the World: The Rise of 440 Hertz in Music, Science, and Politics, 1859–1955 |year=2023 |publisher=University of Chicago Press |isbn=978-0-226-82327-0}}

16 Category:Musical tuning