The knowledge behind the sound

Why 440? And why not?

For an orchestra to sound together, everyone agrees on one reference tone — concert pitch. Today it sits at 440 hertz. That is not a law of nature but an agreement: adopted at an international conference in London in 1939, taken up as an ISO recommendation in 1955, and written down as the standard ISO 16 in 1975.

432 Hz is the concert pitch Radio 432 is set to by default. It sits about 32 Cents measure small pitch differences: 100 cents make a semitone, 1 cent is barely audible. More about cents → below concert pitch A = 440 Hz — just under a third of a semitone. Every note drops evenly; the music stays the same, only a touch lower.

What is measurable is exactly that: the pitch, the distance in Cents measure small pitch differences: 100 cents make a semitone, 1 cent is barely audible. More about cents → , the ratio 54/55. Everything beyond it — warmer, rounder, more pleasant — is attribution and personal listening. Radio 432 claims none of it; it lets you compare for yourself: switch, listen, decide.

Limits of measurement

Not all music can be measured equally well

What's measured is the sound that reaches you — a measurement, not infallible.

Classical recordings often layer many instruments on top of each other, plus the reverberation of the concert hall — the individual pitches blur together more than when only a single voice or instrument is playing. In techno and similar electronic music, much of the sound sits deliberately very low (bass) or very high (hi-hats, noise), outside the range where a pitch can be clearly determined.

Some recordings were also historically not made at exactly 440 Hz, or their pitch has shifted slightly through tape speed and later digitization — this is well documented for the Beatles. Radio 432 then measures, honestly, what is actually in the recording, even when that isn't the expected value.

Single voice or single instrument: needle stays steady — pitch is clearly readable.

Many instruments layered together, or very low/high sounds: needle swings — pitch is only uncertainly readable.

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