Adventures in Vocal Processing

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

Antares Avox

Avox (Mac/Win, $599) is a suite of five vocal-oriented plug-ins that are also available separately from Antares Audio Technologies. They support RTAS and VST formats in Windows XP and Mac OS X, and AU on the Mac. Avox specializes in altering a single voice so that you can either change its character or make it sound like two or more voices.

Throat
Avox's most complex and processor-intensive plug-in is Throat ($249), which Antares calls a physical modeling vocal designer. Throat processes monophonic vocals through an emulation of the human vocal tract and lets you specify a set of modeled vocal characteristics. A graphical Throat Shaping display helps you visualize changes as Throat adjusts the position and width of five numbered points along the vocal tract, beginning with the vocal cords and ending with the lips (see Fig. 3). It also provides points you can click-and-drag in any direction to manually reshape the vocal tract. Below the display are sliders, buttons, and pop-up menus for telling Throat about the source voice and the voice you want to model.

You begin by specifying the source's Vocal Range (Soprano, Alto/Tenor, or Baritone/Bass) and Voice Type (Soft, Medium, Loud, or Intense). Voice Type is expressed in terms of loudness because the amount of pressure applied to the vocal cords affects timbre. The Precision setting (Subtle, Medium, or Extreme) lets you indicate how accurately Throat translates the source voice, which affects the realism of the modeled voice and helps avoid undesirable artifacts; use trial and error to find the best setting. In the Add Breathiness section, Mix and Highpass Frequency sliders let you dial in filtered noise and determine its character. Manipulating the two parameters quite effectively makes a voice sound raspy or turns it into a whisper (see Web Clip 2). In the Model Glottal section, you can use a slider to adjust the waveform's pulse width and a pop-up menu to specify the modeled Voice Type. Another pair of sliders changes the length and width of the entire modeled vocal tract.

Rather than producing radical effects or gender-bending illusions, Throat's 42 presets concentrate on enhancing vocal quality and are designed to be starting points for user settings. Presets include Clarity, Shorter Throat, Larger Mouth, Softer Breathy, Nasalvox, Hoarse, and the like. Because the range of its parameters extends beyond human physiology, though, Throat can produce extreme effects if you desire.

Duo
As its name suggests, Duo ($199) turns a monophonic voice into a mono or stereo pair of voices. Unlike autodoubling processors that merely duplicate a vocal track, Duo lets you apply modeling parameters to the duplicated voice. The modeling controls are much more straightforward and easier to understand than Throat's controls. Four sliders affect the model's Vocal Timbre, Vibrato, Pitch Variation, and Timing Variation (see Fig. 4). By simultaneously affecting several modeling parameters, the Vocal Timbre slider makes the modeled voice less similar to the source as you change its value from the center position. Raising the slider lengthens the modeled vocal tract, and lowering the slider shortens it (see Web Clip 3). Additional sliders let you control each voice's output level and panning.

Choir
Choir ($199) is a more ambitious vocal multiplier that turns a monophonic voice into a vocal ensemble singing in unison with the source. A pop-up menu lets you select 4, 8, 16, or 32 modeled voices. Instead of accessing parameters that control timbre, however, you can adjust only three variations for the modeled voices: pitch, timing, and vibrato. As you raise the sliders, each voice becomes increasingly different from the others while still retaining the vocal qualities of the source voice (see Web Clip 4). A single Stereo Spread slider lets you widen the stereo field.

Punch
The remaining Avox plug-ins are meant to improve the sound of vocals in a mix rather than alter their number or character. Antares calls Punch ($129) a vocal impact enhancer, and you can apply it to either mono or stereo vocals. Punch combines compression and limiting to give a track the power and clarity it needs to cut through a dense mix, though extreme settings can produce distortion effects. The most crucial slider controls Impact, which makes variations in level more equal across the frequency range that vocals occupy. Two other sliders, Gain and Ceiling, allow you to increase the input level and attenuate the output after processing, respectively. Input Level and Output Level meters help to minimize clipping.

Sybil
Sybil ($99) emulates a traditional studio de-esser, which lessens the problems caused by certain consonants when recording vocals. Sybil uses a highpass filter and a sidechain-controlled compressor to reduce a track's overall level when it detects s, t, sh, th, or ch sounds. Sliders control the compressor's threshold, compression depth, attack time, and release time, as well as the sidechain's highpass frequency. A Gain Reduction meter displays the amount of compression being applied.

Cakewalk V-Vocal

Since Roland launched the VP-9000 in 2000, its groundbreaking VariPhrase technology has been acclaimed and admired for its effective audio-stretching algorithms. When Cakewalk released Sonar 5 last year, it became the first native computer software to incorporate those same algorithms in the form of a processor called V-Vocal. Specifically developed for processing vocal tracks, V-Vocal gives you wide-ranging control over pitch, tempo, loudness, and formant structure. You can use it to correct pitch, adjust phrasing, add or subtract vibrato, create harmonies, and perform other feats of studio magic.

In Sonar 5 and Sonar 6 Producer Edition (Win, $619), you activate V-Vocal by selecting some audio data in Track View, and then either pulling down the Edit menu or right-clicking and selecting Create V-Vocal Clip. V-Vocal's window will appear containing a variety of controls and a graphical representation of the selected audio (see Fig. 5). Below the display are controls for mode selection, pitch correction, formant shift, and other tasks, with a tool palette on the left and buttons that control transport and other functions across the top.

When you enable Pitch mode, V-Vocal displays a 2-dimensional graph plotting the original variations in pitch as a red squiggle, overlaid by a pitch curve you can edit, shown as a yellow squiggle. You can adjust pitch manually, click on a button for instant pitch correction, or constrain pitch to follow a scale. Each audio event (typically a word, syllable, or legato phrase) has a horizontal line drawn through it called the Center Pitch; dragging it up or down will transpose the entire event's pitch. Double-clicking anywhere on the pitch curve creates a breakpoint called a Node, which you can click-and-drag up or down to transpose pitch at that location. If you use the Arrow tool to select a portion of the clip and then drag the Center Pitch, new Nodes appear and you can shift only the selected portion. You can redraw pitch using the Line or Curve tools and delete Nodes using the Eraser tool. You can also affect vibrato and other variations in pitch, amplitude, and formant content by using the LFO tool; dragging up from the Center Pitch increases the variation from Center Pitch range, and dragging down decreases it.

Clicking on the Time button replaces the Pitch graph with a more traditional waveform display that plots amplitude against time. You can click near the center axis or double-click between events to divide them into regions, with each division indicated by a green line. Dragging the green line to the left or right expands or compresses the duration of the region.

In Formant mode, a red line appears on the waveform's center axis. Dragging the line up or down shifts the entire clip's formant structure (see Web Clip 5). You can select regions and create Nodes as if you were shifting pitch. In a similar fashion, you can also change amplitude in Dynamics mode.