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The other test was a little more successful—as you can see in the screenshot (Figure F), the two vocal lines did show up as separate, but accompanied by some stray high “notes”—really harmonics that had confused the analysis into thinking they were separate notes rather than harmonic components of one or the other of the two vocal lines. As a result, isolating each vocal revealed a distinctly unnatural timbre (webclip 9B). This kind of analysis confusion is much less common when the notes are all from the same instrument, although there were slight subtle examples of it in the acoustic guitar test. In theory, there is a way to address analysis issues, should they occur, but it’s not for the faint-of heart, nor the non-technical musician. Melodyne has an advanced editing feature called the Note Assignment Tool for someone comfortable enough with harmonic theory (see the sidebar) to be willing to second-guess the program’s internal analysis. With this tool active (Figure G), Melodyne displays the harmonics detected when it analyzed the two-voice audio file. The editing display normally shows only the fundamentals of the pitches Melodyne detected, with each note’s harmonics hidden and adjusted automatically when the fundamental is edited. With the Note Assignment Tool active, the harmonics are all visible and can be reassigned, or, if a harmonic is strong enough to be mis-assigned as a separate note, that false note can removed and reintegrated into one of the existing note fundamentals. I removed the false notes shown (Figure H), which did improve the timbral quality of the individual vocal lines somewhat (webclip 9C), but there was still enough tonal artifact remaining to bolster Celemony’s warning that instrument extraction is not a supported feature, despite our desperate lusting after it! However, it’s clear that the potential exists—perhaps sometime in the future, Celemony? State of the edit That last limitation notwithstanding, the current state-of-the-art in pitch processing is clearly very high indeed—and I barely touched the more esoteric features of Melodyne (and other pitch processors). The real trick, as many in the music business would be quick to affirm, is to use all this pitch-processing power for good rather than evil—and with that thought, happy editing! Joe Albano (albano@recordingmag .com) is a musician/engineer/producer/ audio consultant in NYC—he can be reached through his production company’s website at www.rooftoprecording.com.
RECORDING MAY 2011

Harmonics and DNA It’s basic physics that all complex sounds (like notes from a guitar, as in the audio examples for this article) are made up of individual pure tones (sine waves) of different frequencies, called partials. Normally, different partials would sound like different pitches, but when they’re part of a single note our ears blend them together—we perceive the pitch of the lowest tone only (the fundamental) and the others are perceived as contributing to its timbre, or tone quality. This is what gives sounds their infinite tonal variations, and makes music a joy to listen to. It’s also how Melodyne’s DNA feature works its magic—Melodyne analyzes complex sound waves, like polyphonic notes from a musical instrument, figures out which harmonics go with which fundamentals, and then separates them, giving the user editing control on a note-by-note basis. But too much of a jumble of harmonics, as you might get with different instruments combined in the same audio file, can confuse things, which is why Melodyne can’t separate different instruments reliably... at least not yet.—JA

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Recording - May 2011

Table of Contents for the Digital Edition of Recording - May 2011
