432 Hz converter

What the 432 Hz converter does to a song

It multiplies every frequency in the file by 432/440, which is 0.9818. The A above middle C goes from 440 Hz to 432, middle C from 261.63 to 256.87, a bass E from 41.20 to 40.45. That is 31.8 cents, a little under a third of a semitone, the same for every note, so the melody, the chords and the intervals between them stay exactly as they were. It is as if every instrument on the recording had been retuned by the same small amount.

How: the song is first slowed down by 1.8 %, which lowers its pitch the way a slow turntable does, then put back to its length in slices of 50 ms, each laid where it lines up with the last (a method called WSOLA). The tempo stays, the length stays to the sample. On very sharp drum hits and deep sustained bass the slicing can leave a faint trace; switch between the two versions and listen for it.

What it can't know

It does not measure what the song was tuned to; it lowers whatever is there. A recording already at 432 comes out at 424, and plenty of records were never at exactly 440: many orchestras tune to 442 or 443, and old tapes ran a little fast or slow. To see where a held note of the song sits, play it into the pitch detector; to tune your own instrument to 432, use the 432 Hz tuner.

Does 432 Hz sound better?

This page claims nothing for it, and nothing here was measured on people. The number has a history: Verdi argued for an A of 432 to spare singers, and Italy prescribed it in 1884; with middle C at 256 Hz, 2 to the 8th, the old Pythagorean way of stacking fifths lands on an A of exactly 432. The world settled on 440 in London in 1939, written into ISO 16 in 1955. The story that 432 matches the Earth's Schumann resonance does not hold: that is about 7.83 Hz, not 8, and it is a radio wave, not a sound. The 432 Hz tuner page tells the whole story. Whether you can hear the difference at all is a question you can answer with the 432 vs 440 test.

The file you get

A WAV with the song's channels and its sample rate, 16 bits, named after the song with -432hz added. Nothing about the song leaves your phone or computer: the browser decodes it, the page retunes it, and the WAV is made in the tab. It reads the first ten minutes of a longer file.