Pitch correction is one of the most used - and most argued about - tools in modern production. Used transparently, it tidies a great performance without anyone noticing. Used as an effect, it has defined the sound of entire genres. Knowing how to do both is essential.
A short history
Pitch correction did not begin with computers - producers used pitch shifters and careful editing long before. But Antares' Auto-Tune, released in the late 1990s, changed everything. When it was pushed to its fastest setting on Cher's "Believe" in 1998, the robotic stepping between notes became a sound in its own right, later taken up and made central to hip-hop and R&B by artists like T-Pain.
Today, pitch correction is used on the majority of commercial vocals, often so subtly that listeners never notice.
The main tools
- Automatic (real-time) tuning - Auto-Tune and similar plug-ins, plus built-in tools such as Logic's Pitch Correction. You set a key or scale, and the plug-in pulls notes towards the nearest correct pitch in real time.
- Graphical tuning - Celemony's Melodyne, Logic's Flex Pitch, Cubase's VariAudio and similar tools. The vocal is displayed as blobs of pitch on a piano-roll grid, and you correct each note individually.
Automatic tuning is fast and essential for the effect sound. Graphical tuning is precise and better for transparent correction.
Retune speed
The key control on automatic tuners is how quickly a note is pulled to the target pitch.
- Slow - natural. Small inaccuracies are nudged, vibrato and slides survive, but serious errors may not be fully fixed.
- Fast - corrects everything, but removes natural slides between notes. At the fastest setting you get the stepped, robotic effect.
For transparent tuning, use the slowest speed that fixes the problem, and set the correct key and scale so notes are not pulled to the wrong pitch.
Graphical tuning in practice
- Pitch centre - move each note so its average pitch sits on the correct note.
- Pitch drift - reduce wobble within a long note, but do not flatten it completely.
- Vibrato - keep it. Reduce it slightly if it is uneven or wide; removing it entirely sounds artificial.
- Transitions - the slides between notes are where much of a singer's style lives. Leave them alone unless they go badly wrong.
- Timing and length - most graphical tools can also move and stretch notes in time.
Formants
Formants are the resonances that give a voice its character - why one person sounds different from another singing the same note. Shifting pitch without preserving formants makes voices sound chipmunk-like when raised or monstrous when lowered. Most modern tuners preserve formants automatically, and many let you shift them separately for creative effects.
What not to fix
- Notes that are expressive rather than wrong. A slightly flat note at the end of a sad line may be the emotion.
- Blue notes - deliberately bent notes between major and minor in blues, soul and R&B.
- Performances with a deliberate rough edge - many genres value character over precision.
Always tune in context with the track, not soloed. A note that sounds wrong solo may be perfectly fine in the mix - and vice versa.
The effect sound
To get the obvious tuned sound deliberately:
- Use an automatic tuner on its fastest retune speed.
- Set the correct key and scale - the effect depends on notes snapping to the right targets.
- Sing with it on, if you can. Singers who perform through the effect learn to work with its stepping, and it sounds far more musical.
- Combine with doubles and harmonies for the full modern stack.
Do this now
- Run a vocal through an automatic tuner with the correct key, first at a slow retune speed, then at the fastest. Describe the difference.
- In a graphical tuner, correct the pitch centres of a verse without touching the vibrato or transitions.
- Find one note you would deliberately leave untuned, and explain why.