Adventures in Vocal Processing

Nov 1, 2006 12:00 PM, By Geary Yelton

Waves Vocal Bundle

Waves Vocal Bundle (Mac/Win, $1,000) is a suite that comprises five plug-ins: Tune, DeBreath, Doubler, Renaissance Channel, and Renaissance DeEsser. All but one are native and TDM compatible, and Tune is native only. Three of the plug-ins are available separately, but Renaissance Channel and DeEsser are available only in bundles. And if you happen to own one of several other Waves bundles, you may be entitled to download Tune LT, a lite version of Tune, at no additional charge.

Tune
Treading territory similar to Auto-Tune's and V-Vocal's, Tune ($600) corrects pitch errors and lets you graphically manipulate the pitch of monophonic instruments and vocals on mono or stereo tracks. Tune uses ReWire to synchronize with your digital audio sequencer, ensuring that its display always matches what you hear during playback, allowing you to listen to all your tracks simultaneously, and letting you control transport functions from within Tune.

Tune's piano-roll Edit window, a grid that plots pitch against time, dominates its graphical user interface. After you've set parameters such as your track's vocal range (Bass through Soprano) and indicated its root and scale type, simply play the track, and Tune will detect and transpose every sharp or flat pitch to the nearest correct pitch and display notes as a series of Segments (see Fig. 10). The original pitch curves will appear as orange squiggles, with the corrected pitch curves appearing as green squiggles. Speed, Note Transition, and Ratio knobs let you tighten or loosen the correction. Although formant correction is enabled by default, you can disable it if you'd prefer an unnatural sound.

After scanning, you can use the Note tool to select any Segments you want to manipulate further. Additional tools let you split and join Segments, move around in the Edit window, zoom in or out, and redraw any portion of the pitch curves. Controls in Tune's Segmentation section let you specify conditions for segmenting correction curves into notes. If you select a Segment and then click on the Vibrato button, Tune will highlight any part of the selection it perceives as vibrato. You can then apply any changes you make using controls in the Vibrato section — even adding vibrato that sounds natural or synthetic (see Web Clip 10).

DeBreath
DeBreath ($350) automatically and selectively removes or attenuates the sound of inhaling and exhaling from monophonic vocal tracks. Unlike more traditional techniques that rely on noise gating, DeBreath is based on an algorithm that detects breaths by comparing them to a library of templates and then separates them from the rest of the signal.

Although DeBreath's defaults are all you need under most circumstances, several controls let you customize its settings. A Breath Graph tracks the similarity between the audio track and the library's templates; anything above its threshold is considered a breath. The Energy Graph displays the signal's total energy; anything above its threshold is not considered a breath, even if the Breath Graph sees it as one. Sliders let you change either threshold to fine-tune the breath-detecting process. You can specify how quickly a breath fades out from the voice path and how quickly it fades back in again. You also control the amount of gain reduction applied to breaths, ensuring a natural sound that doesn't leave gaps in the vocals. You can choose to monitor either the voice or the breath individually.

Renaissance DeEsser
Like other de-esser plug-ins, Renaissance DeEsser is a compressor that uses sidechain filtering to attenuate sibilance — s, t, ch, sh, and th sounds. Its crossover, like those in other Waves compressors, compensates for phase modulation that would otherwise color the sound. Renaissance DeEsser's threshold setting dynamically adapts to the input signal, also contributing to more natural results. A graph helps you visualize your settings, with colored lines representing the crossover's active and passive ranges, the gain's attenuation range, and frequency-dependent attenuation.

You can choose to monitor either the audio or the sidechain. After you've aurally identified the problem frequency, simply adjust the threshold to attenuate it. Use the Range slider to set the maximum gain reduction, which determines how much de-essing is applied. Additional controls let you specify highpass or bandpass filtering for the sidechain, the filter's cutoff or center frequency, and a compression mode. Renaissance DeEsser comes with several presets appropriate for male or female voices or for a full mix.

Renaissance Channel
Renaissance Channel furnishes 4-band EQ, compression, and other channel-strip functions. Although it is part of Waves Vocal Bundle, Renaissance Channel has no features that make it vocal specific. Consequently, there is no need to discuss it in any detail as part of this article.

Doubler
Despite its name, Doubler ($200) offers more than simple voice doubling; it adds as many as four voices to vocal tracks. Doubler is actually six plug-ins, comprising 2- and 4-voice mono, stereo, and mono-to-stereo versions. Every version supplies a control strip for each of the doubled voices. You can specify each voice's gain, delay, feedback, and tuning parameters, as well as enable or disable voices. Shift any of the voices an octave lower and specify the depth and rate of LFO modulation. Stereo versions also let you govern the panning of each voice, including the original.

Three displays give you visual feedback and allow you to change parameters graphically (see Fig. 11). One shows the relative gain and stereo positioning of all voices. Another lets you individually change each voice's delay time and detuning, with each voice represented as a colored ball surrounded by moving lines that represent modulation. In the EQ display, you can apply high- and low-shelf filtering to all the doubled voices and graphically change the equalization curve.

Doubler is quite effective at thickening vocal tracks and giving them a nice studio sheen (see Web Clip 11). It's also capable of LFO-controlled panning, pitch-bending, and delay effects ranging from flange to echo. Waves furnishes 19 Doubler presets for a variety of applications and effects.

Turn Geese into Songbirds

As you can see, vocal-processing software can accomplish many transformations that were previously impossible. Only a few years ago, you couldn't change a recording's pitch without affecting its duration or change its duration without affecting its pitch. How well vocal-processing software will perform, though, depends a lot on your expectations. It's still very difficult to begin with a recording of someone who can't sing and turn it into a passable performance. With sufficient effort, you can seemingly cure a bad sense of pitch and a worse sense of rhythm. You can modify a singer's vocal timbre, enhance his or her breathing technique, and turn one singer into as many as you need. You can even add richness and tone to a voice that has none; just don't expect it to sound real.

When the original performance is lacking, you often have to push software to extremes. When that happens, audible artifacts introduce an unavoidable artificial quality to the sound. The problem must be in the nature of digital audio, because whenever I exceeded limitations that were instantly obvious, all the software I tried exhibited a tendency toward making human voices sound synthetic. Of course, a voice that sounds like a machine is desirable for some types of music, and nothing makes a voice stand out like destroying its organic nature.

To effectively process vocals and retain their natural qualities using any of the software surveyed here, the trick is to immediately recognize when something begins to sound artificial and pull back a bit. Admittedly, that can be difficult when you're so wrapped up in an editing session that you lose perspective. If you're correcting pitch, try lowering the speed setting. If you're transposing a harmony part, use the smallest interval you can get away with, and accept that an octave is simply too far. If you're compressing or expanding time, never go beyond halving or doubling tempo, and avoid going that far whenever you can. The difference in one person's voice and another's may be subtler than you imagine. It also helps to bury vaguely synthetic-sounding voices deep in the mix or smear them with reverb. Believe it or not, such techniques can work very well and still sound good.

Don't forget that singers rely on audio professionals to make them sound good, and sounding good is more important than a flawless recording. Achieving natural results depends on using your ears and accepting any limitations your ears recognize. Unless you or your client are willing to accept vocal tracks that sound unnatural, you will often encounter instances when it's preferable to record another take rather than waste time trying to process tracks into submission. The key to successful vocal processing, then, is to know when enough is enough.

Since 1985, Associate Editor Geary Yelton has written hundreds of reviews and feature stories for EM.

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