There's Out-of-Tune and Then There's Auto-Tune

One thing that a lot of folks seem to continually miss is that the 12 Tone Equal Temperament intonation system is -- by necessity -- out of tune with itself.

Out of 12 equally tempered tones, eight are more than 10 cents out of tune from perfect harmony! (Depending on harmonic context.)

That's right -- that same 'perfect' little grid you see in A-T or other vocal retuners incorporates intervals which are all -- except for octaves -- varying degrees out of tune.

The upshot is that those particularly oriented to the slightly out 12TET intervals may interpret a technically accurate singer as being "out of tune" -- particularly if the musical arrangement is poorly crafted and juxtaposes equally tempered instruments with hold-tones (notably synths and organs) against a singer who might be singing the true interval. Contextually, most of us will leap to the conclusion the singer is out of tune when, in fact, the singer may actually be singing the proper interval.


12TET is an amazing accomplishment in some ways, allowing us to have 12 fixed tones that approximate the true tone relationships in any key. It made modern western music, including the piano and guitar and other 12TET instruments, possible and workable. (12TET is not the only intonation system available or possible, but it serves as something of a central standard.)


But it also means that all the intervals except the octaves are out of tune. Perfect fourths and fifths are only 2 cents out -- but a minor 7th may be seen as as much as 31 cents out. And, as I noted above, 8 of 12 tones are more than 10 cents out.

Here's a chart that shows the true ("just"), mathematically correct and purely harmonious intervals contrasted with the 12TET 'approximations' with the differences in the far right column:

Equal temperament - Wikipedia, the free encyclopedia


So... next time you're dragging what your eye tells you is an out of tune vocal snip onto the grid, keep in mind: you may be dragging that vocal out of tune with itself. (But then, you may have to -- in order to get it to play nice with keyboards or long guitar notes or chords. It's a tricky business, no question. But the bottom line is that most folks don't get it, don't have the first clue as to what really goes into intonation.)