Recording - May 2011 - 32

In harmony As a simple test, I ran a vocal track (a gravelly deep-voiced singer, audio webclip 1) through Melodyne for basic pitch correction (Figure A, webclip 2), and then used Melodyne to manually re-pitch selected notes of the lead vocal line to create a basic harmony part (Figure B, webclip 3). For me, dragging the notes by hand to create the harmony is preferable to setting up a scalelimited transposition in automatic pitch-correctors, since I usually know what I’m looking for in a harmony line, and this gives me more flexibility. However, I can see how some people might prefer the software to do more of the work of determining which pitches would and wouldn’t fit in a harmony line in a particular key—while I don’t tend to use them, Melodyne does have these kinds of scale-based options as well. This particular harmony line involved pitch shifts of as much as several semitones up, where you can hear that a little unnatural tonality has crept into the voice on the highest harmony note(s) (webclip 3). Melodyne includes a note-by-note formant editor which is very handy for this type of situation—a suitable formant adjustment on the particular notes that are pulled a little too far, without messing with others that sound ok, is just the ticket to tame a stray quack here and there. However, I didn’t apply formant adjustment to the artifact(s) in the audio example, so it would clearly demonstrate what approaching the limits of this technology can sometimes sound like. When I created the harmony line, I realized that the wide vibrato present on the original melody was way too much for a harmony (unless this was to be a Bee Gees tribute). This vibrato can be heard clearly in the example of the original vocal line, and seen in the screenshot (Figure C) as the wavy lines over some of the notes. (Incidentally, the other lines swooping into or out of notes are the subtle vocal slides that singers all do between notes. They’re usually not very noticeable until you remove them entirely with software—then you have the dreaded Cher/T-Pain effect of perfectly quantized pitch articulation!) Melodyne allows all of these subtle pitch shifts to be adjusted independently of the main note pitch—this is one of its most powerful features, in my opinion. The glides are edited by the “pitch drift” tool, and the vibrato by the “pitch modulation” tool. I used the latter to smooth out the strong vibrato on the sustained harmony notes (Figure D) so they wouldn’t lock in too much with the original melody—after all, this is supposed to simulate a different performance, and a harmony singer probably wouldn’t put as much “english” into his performance, so as not to overshadow/clash with the lead. The finished blend of original vocal with the harmony doubled and panned in stereo, plus a little reverb added, can be heard in webclip 4.
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The building blocks of sound I was most curious to do some experimentation with the Direct Note Access (DNA) feature, which I had not previously had occasion to use in a studio setting (outside of seeing it demoed with prepared audio examples). I first grabbed a strummed acoustic guitar part to see how well Melodyne would do separating the individual notes in a real-world situation. As you can see and hear (Figure E, webclip 5), Melodyne had no trouble separating the individual notes of the chords, although it also generated a few stray pitches that didn’t really belong, possibly finger squeaks or stray harmonics that confused its analysis engine—more on this later. I proceeded to change the chords around (minor to major, etc.), and also added a few rhythmic variations (a few suspensions here and there for variety)—compare the chord progression in webclip 5 to the altered version in webclip 6 to hear the differences. On the whole, the re-chorded version sounds almost entirely natural, with only a direct comparison to the original drawing attention to what may be a few minor artifacts—not bad for a fast and dirty edit! Here and there, Melodyne seemed to sound a note or two that had a slightly odd tonality—in a couple of cases I was able to improve that with very slight formant shifts, courtesy of the Formant tool, but there is another way to address those occurrences, which I’ll mention in reference to the last example, below. I also decided to test a MIDI feature of Melodyne that comes with all versions except Essential—the ability to export a Standard MIDI File from the note/pitch information detected. Other programs have been doing this successfully for years with monophonic material, so I decided to try it with the polyphonic guitar I had just processed. The resulting MIDI file, imported into Logic and assigned to a suitably tweaked acoustic guitar Sample Instrument, can be heard in webclip 7. Some additional adjustment to the velocity response of the MIDI Instrument would help (MIDI-simulated strumming always sounds fairly stiff to my ears), but the note extraction did accurately reflect the (altered) chords in the DNA-edited audio file. Pushing the envelope As a final test, just for the heck of it, I decided to see how Melodyne would handle something it pointedly claims not to do—separate different instruments combined in the same audio file. Celemony clearly state that Melodyne’s analysis is designed to separate pitches, not instruments—if different instruments were combined in the same file and played different notes, they might be able to be separated, but if two instruments played the same pitch, the resulting note in Melodyne’s edit window would represent both instruments together. At any rate, I decided to give it a go with two tests: a simple vocal line against an acoustic guitar (webclip 8A), where some notes probably did overlap, and a pair of simple vocal harmony parts (webclip 9A), that definitely didn’t have any overlapping (same) pitches. In the first case, as forewarned, Melodyne was unable to separate the voice and guitar—not only that, but it seemed to assign harmonics from one to the other, so that when I clicked on a note, I would hear a combination of voice and guitar tone, for a very odd tonality (webclip 8B). Attempting to isolate just the vocal notes or just the guitar notes was futile, as promised.
Recording - May 2011

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