Autotuning: Making the Most of Pitch Correction Software

Ever since Antares AutoTune revolutionized vocal recording nearly 20 years ago, the idea of fixing pitchy performances has been a point of debate for musicians and listeners alike.

Genres like dance and country have embraced the so-called Cher or T-Pain effect with many producers no longer batting an eye at listeners being able to immediately recognize the corrective software at work. Others prefer pitch correction’s more subtle uses.

Most would agree that being equipped to fix the odd, errant note is freeing because it lets performers concentrate more on things like emotion, tone and phrasing – the things that software can’t fix. But finding the balance between natural and pitch-correction on your track can be tricky. If you’re going for a natural sound, for instance, how much correction is too much?

“I’ll be honest – my aesthetic approach is usually to avoid slight pitch adjustments,” says Matt Hines of iZotope, makers of the Nectar 2 vocal effects plugin. “If it’s close enough, I prefer the natural performance. That said, there are many times in production where pitch perfection is called for.”

According to Hines, the art of pitch correction involves a few key parameters that are common to heading programs like AutoTune, Nectar, Waves Tune, Synchro Arts Revoice, Celemony Melodyne, and the pitch-correcting tools that are built into many of today’s leading DAWs and hardware/live pitch-correcting units.

“There's really no one size fits all,” Hines says. “It's more about just listening through and making sure the audio sounds natural post pitch correction.”

Keeping It Real or Getting Graphic

Most pitch correction plugins have two operating modes: real-time, where the effect works on playback, and graphic, where the software analyzes the material first before letting the user manually adjust individual notes.

The fastest and easiest way to use pitch correction is in real-time mode, and if you’re going for the electronic “pitch corrected” sound, it’s a good place to start. But real-time mode can also be used for more subtle corrections.

The effect is largely defined by three settings: speed, amount (given as a percentage), and scale. The faster the speed, the less natural the movement between notes will sound. The higher the amount percentage, the more aggressive the correction will be.

“Fast and full” defines the robot sound. But what if you want the pitch correction to be less noticeable? “If I’m using real-time pitch correction, I tend to favor a much slower response time and correction speed – 100ms or more,” Hines says. “This helps pull the worst offending notes tastefully closer to pitch without sounding robotic or ‘grabby.’ I employ a graphic pitch editor for the worst offending notes.”

A Matter of Scale

When first loaded, most plugins define the “correct” pitch as a note on the equal tempered chromatic scale where all 12 notes in an octave are separated by the same interval. If you’re unfamiliar with various intonation methods, this can seem like the obvious way to go. After all, it’s used by electronic keyboards, many pianos, and – at least in theory – by fretted instruments.

But voices, unfretted strings, and winds don’t necessarily benefit from equal temperament tuning. A choir can produce rich chords by singing diatonic intervals that are actually a little sharp or flat when compared to their equally tempered counterparts. (You can read about the science behind it here.) The difference is audible, especially with intervals like a major third, which is more than 2.5Hz lower in diatonic intonation than it is in equal temperament.

If your pitch-corrected notes sound harsh or clashy, try setting the plugin’s scale to match the key of your song. You can also experiment with exotic scales and modes.

“I have found that diatonic sounds more natural at gentle, real-time pitch correction settings,” Hines says. “But if I start doing more aggressive pitch correction, then choosing a chromatic scale works best.” If you want to preserve notes that fall outside of the scale, you can usually set the plugin to ignore them, or go in and adjust them in graphic mode.


Formants and Vibrato

Two other areas of pitch correction to explore include formants, which affect the tonality of the note, and vibrato, which can restore some of the natural pitch movement to a corrected note.

“As we sing, our formants naturally shift,” Hines says. “Sometimes, you may achieve more organic pitch correction by shifting formants slightly in the direction of the pitch shift, such as an upward formant adjustment as a singer goes higher.”

According to Hines, vibrato may be the most underutilized feature of good pitch correction software. “Many graphic pitch editors – Nectar 2 included – let the user create, enhance or flatten vibrato in any given note,” he explains. “This is so crucial to retaining a natural-sounding, pitch-corrected performance. And when ignored or underutilized, it usually sounds robotic – even at more gentle response times and correction speeds."

Hines explains that your vocals will sound robotic because "you risk removing all of the desirable, musical pitch variation at the same time as you’re correcting the overall perceptual pitch. This feature is actually quite simple. Generally, a knob or fader (depending on whose software you’re using) allows you to artificially increase, naturally preserve, or artificially reduce the amount of pitch variation as the note sustains.”

Don’t Forget Context

It’s important to remember that how you use pitch correction should be determined by the song. "Before tuning a vocal for the sake of it, you want to make sure that the pitch adjustment sounds good when it's blended into the mix," Hines advises. The best results may not be the pitch-perfect ones, even if you’re going for an obviously pitch-corrected sound. “I generally recommend not soloing the track while doing pitch correction because you run the risk of making the vocals sound pristine in isolation, but not quite fitting in with the rest of the mix.”

And finally, bear in mind that pitch correction might not be the way to go at all for some tunes. Take a minute to consider what would have been lost if Ringo's pitch was corrected while he was singing out of tune about singing out of tune. With some songs, it's their natural and subtle imperfections that make them absolutely perfect.

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