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Making Tracks: Creative Pitch Correction

April 1, 2009
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Vocal repair is the bread-and-butter application for pitch-correction software such as Celemony Melodyne, but I'd rather just work with a singer who has good pitch. That leaves me free to explore the more creative uses of tuning software. Look beyond the autocorrection aspects of the program, and you'll find plenty of opportunities for making cool sounds.

Just Desserts

One thing that always bugs me about emulative synth parts is equal-tempered keyboard tuning. No horn or string section “tunes” chords in the way a piano does. The thing that makes a great horn section really pop is each player's ability to bend notes up or down slightly to align the notes of a chord properly. When possible, instrumentalists and singers tune harmonic intervals to just intonation, which is based on the natural integer ratios of the harmonic series. (For links to useful information about tuning, see the online bonus material at emusician.com.)

The moral of the story is that if you use autotuning software recklessly, you risk taking the natural tuning adjustments out of the harmony parts. Armed with a knowledge of what to look for and, more important, a keen ear, you can restore the intervals to their proper size (the size that really good musicians would have played and sung to begin with). The most obvious fixes include perfect fifths and minor thirds, which should be slightly wider, and major thirds, which should be slightly narrower.

In Web Clip 1, I apply this principle to MIDI-triggered string samples in Cakewalk Sonar. Using a respected sample library, I recorded a simple 3-part I-V-IV-I phrase and printed each part to a mono audio track. On each of these tracks, I linked to Melodyne using the MelodyneBridge plug-in. MelodyneBridge is one step short of a real-time plug-in, in that you must transfer the audio into Melodyne (running alongside the host) before tuning it. Once the audio is in Melodyne, any changes you make will play back immediately in the host.

FIG. 1: You can tune your tracks more sonorously by tweaking individual notes by small amounts. Melodyne''s Selected Note Offset lets you tweak pitch in hundredths of a semitone (cents).

FIG. 1: You can tune your tracks more sonorously by tweaking individual notes by small amounts. Melodyne''s Selected Note Offset lets you tweak pitch in hundredths of a semitone (cents).

When Melodyne's Edit Pitch tool is active, you can adjust selected notes in hundredths of a semitone, called cents, by typing values in the Selected Note Offset field (see Fig. 1). Curiously, I had to correct the root of the tonic chord by a couple of cents. I then tuned the fifth of each chord up by 3 cents and the third (they were all major thirds) down by 13 cents. To maintain continuity from chord to chord, I tuned the V chord from the slightly sharp fifth scale degree and the IV chord from the key's tonic.

Having thus satisfied theory, I threw caution to the wind and made my final tweaks purely by ear. I adjusted nothing more than a cent or two, and I attribute most of the adjustments to the inherent minor imperfections of the samples.

Horn of Plenty

When blending acoustic instruments and synths, it can be tough to match phrasing as nearly as you'd like. The biggest obstacle is that a saxophone, for example, is a very different type of controller from a keyboard. Playing the synth parts on a wind controller such as the Akai EWI can help significantly, but that isn't always an option.

Melodyne's pitch-to-MIDI conversion is accurate enough and has enough performance detail to help create the synth parts directly from the acoustic tracks that they're supposed to match (see “Step-by-Step Instructions”). You can do only so much to make a synth part convincingly emulative, of course, but if you can match the phrasing well enough, it will sound like a skillful and deliberate orchestration choice (see ).

The key is to include enough controller data to bend and shape the synth part in the way that an acoustic performer does. Melodyne exports pitch variation as MIDI Pitch Bend data and exports volume as a combination of Velocity and a continuous controller (CC 11 by default). You can bias both Velocity and controller values by adjusting graphic response curves, much like those on a keyboard controller.

Pitch-bend amount must be matched to that of the synth, and Melodyne features three pitch-bend modes to suit different situations. I found dealing with a couple of horn falloffs to be easier using the Transition (portamento) function than the pitch bend. It's a good idea to clean up any pitch-detection errors in Melodyne before exporting to MIDI, as the note numbers, pitch bends, and transitions are interrelated.

Sophisticated tools such as Melodyne are too often either abused and overused or discounted as a form of cheating. Used imaginatively, however, pitch-correction software ends up being the ultimate bridge between acoustic and electronic instruments. Sometimes plain old curiosity — not necessity — is the true mother of invention.


Saxophonist and composer Brian Smithers is department chair of workstations at Full Sail University.

STEP-BY-STEP INSTRUCTIONS ON NEXT PAGE

1

Step 1: Transfer audio from the host into Melodyne using the MelodyneBridge plug-in.

2

Step 2: Show the audio-to-MIDI parameters in the Editor window. You can do this from the View menu or the MIDI menu.

3

Step 3: Enable export of pitch-bend and envelope data, choosing the appropriate controller number and pitch-bend mode. Tweak the Velocity and envelope curves if necessary.

4

Step 4: Correct any misanalyzed notes within Melodyne before exporting. Tweak the intonation of individual notes for optimum harmonic effect.

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Step 5: Use the Save Audio As MIDI command to export the desired tracks to individual Standard MIDI Files. To preserve alignment between tracks, set the Range to From Start Of Reference Track Until End Of Arrangement.

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Step 6: Import the MIDI files to the appropriate tracks in your host sequencer and assign them to the desired synths. Be sure that the synths'' pitch-bend ranges match the range set in Melodyne.

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