Concert Pitch, ISO 16
440Hz
Concert Pitch, ISO 16
The zero point. Not because it’s better, but because it is the international reference pitch, set in ISO 16.
Chladni figure · n 5.05 · m 8.07
What happens when you switch
Small enough not to notice.
At 440, Radio 432 tunes the measured music to 440 Hz: if it already sits there, the sound stays unchanged; otherwise the app shifts it by the measured difference. If there is neither a current measurement nor one saved for the station, it changes nothing. You hear the original sound without retuning when you tap the frequency gearbox in the player on iPhone or iPad; to compare, you switch back and forth this way between the original sound and the selected frequency.
Origin
How 440 became the standard
For a long time there was no unified tuning at all — every town, every opera house, every organ had its own. That wasn’t an oversight; it was normal, because music didn’t travel.
In 1834, the physicist Johann Scheibler in Stuttgart first proposed an A at 440 Hz. In 1939 it was agreed internationally in London, in 1955 the ISO recommended it, and since 1975 it has stood as the standard ISO 16.
A standard is a convention, not a law of nature. It makes it possible for two orchestras from two countries to play together — it was never meant to be more than that.
All ten, as the ear hears them
Plotted in Cents measure small pitch differences: 100 cents make a semitone, 1 cent is barely audible. More about cents → relative to 440 Hz — the unit the ear actually reckons in. A semitone is 100 Cents measure small pitch differences: 100 cents make a semitone, 1 cent is barely audible. More about cents → , an octave 1200.