Concert Pitch · Theory

Pitch Octave Note Name Historical Performance Practice

The phrase "standard pitch" suggests pitch standards have always existed. The opposite is true: it is a recent invention, and it was forced on musicians. Before it, every church and every town could keep its own pitch.

How A4 = 440 Hz came about

Pitch has to be unified because instruments have to play together. Organs, woodwinds and brass are fixed to a pitch at the moment of manufacture. A flute built in a town at A = 435 is entirely sharp the day it joins an ensemble playing at A = 450.

The chaos peaked in the nineteenth century: orchestras kept raising pitch because a brighter sound sold more tickets, while the burden on singers and string players grew with it. That created pressure to standardise.

Year	Event	Pitch
—	Pitch commonly used in the Baroque era	A4 = 415 Hz
1859	France establishes the "diapason normal"	A4 = 435 Hz
1939	London international conference recommends unification	A4 = 440 Hz

A4 = 440 Hz was written into international standards afterwards and is today's concert pitch. When someone says "this note is A", the default meaning is that 440 Hz A.

Diagram: where the three standards sit

Why it deserves an entry of its own

Because pitch standard is the precondition of performance practice, and the dividing line in historical playing.

Ensembles tune first. The tuning moment at the start of a concert brings everyone toward one reference. Only after that can intonation mean anything.
Transposing instruments need conversion. The written name may be the same, but the sounding pitch depends on the instrument's construction and on the standard. See note name.
Period performances change standard. Playing Baroque music at 415 Hz today restores the original instrument build, string tension and vocal burden. That is a performance-practice question — see historical performance.
Equal spacing on a keyboard depends on it. Equal temperament cuts the octave into twelve; where those twelve then sit in absolute frequency is decided by the standard. Shift the standard and the whole keyboard shifts.

Listen: A4 and its octave

Common misconceptions

"A means 440 Hz." A is a note name; 440 Hz is the frequency assigned to the name A4 in modern practice. The letter itself contains no number.
"Unified pitch is better, so earlier musicians were backward." Differing local pitches were the norm rather than a mistake. Unification serves ensemble playing, not correctness.
"A tuner reading 440 means perfect intonation." It means this one reference matches. Overall intonation still depends on instrument build, technique and the temperament chosen.
"Period performance simply means lower pitch." 415 Hz is a common choice for Baroque repertoire, but historically pitch ran both high and low, not consistently lower.

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Listen in the library

Sound Ye the Trumpet CallC10:35An organ hymn — pipe lengths fix the pitch permanently once built — the most stubborn carrier of any standardDetailsScales, Arpeggios, and CadencesC13:22Scale and arpeggio exercises — a keyboard tuned in equal temperament needs one agreed pitch for its equal spacing to mean anythingDetailsOld 100thC10:23The hymn tune Old 100th sung by voices — the voice has no fixed pitch of its own, so an outside reference has to be taken before it startsDetails

All tracks from midicn-lib — inline badge is the license tier (C1 commercial / C2 non-commercial / C3 study only).

Sources

A4 = 440 Hz 的国际标准由 1939 年伦敦国际会议建议、后经 ISO 16 确立，为公认事实
1859 年法国确立 435 Hz、巴洛克时期常用 415 Hz，均为乐律史通行记载

Used for fact-checking only; all prose is original.

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