AuxFormant User Guide & Vocal Pitch Manual
Independent vocal pitch transposition, spectral formant envelope reshaping, throat morphing, and robotic tuning powered by the Signalsmith Stretch engine.
1. Overview & Acoustic Decoupling
In human vocal anatomy, pitch (the fundamental frequency $f_0$ determined by vocal cord tension) and formants (the physical resonant cavities of the throat, mouth, and nasal tract) are acoustically separate. Traditional pitch shifters transpose both together, creating the infamous artificial "chipmunk" or "monster" effect. AuxFormant fully decouples pitch from formant resonances, allowing you to transpose a vocal two octaves up or down while maintaining natural human timbre.
2. Complete Knob & Parameter Reference
| Knob Name | Parameter ID | Range & Unit | Default | Acoustic Function & Listening Tip |
|---|---|---|---|---|
| Pitch | pitch |
-24 st – +24 st | 0 st | Musical Transposition. Discrete integer semitones. Shifts musical pitch up or down two full octaves without changing perceived vocal tract size or timbre. |
| Formant | formant |
-12 st – +12 st | 0 st | Vocal Tract Scaling. Shifts acoustic resonant formants independently of note pitch. Negative values sound deeper and masculine; positive values sound smaller, feminine, and bright. |
| Throat | throat |
-100% – +100% | 0% | Geometric Cavity Morphing. Negative values simulate shorter physical vocal tracts (head voice resonance); positive values add rich chest resonance and throat depth. |
| Drive | drive |
0.0% – 100.0% | 0.0% | Warm Vocal Saturation. Adds euphonic 2nd and 3rd order harmonics directly to the shifted audio, helping transposed backing vocals cut through dense modern trap and pop tracks. |
| Spread | spread |
0.0% – 100.0% | 50.0% | Stereo Detuning & Width. At 50%, maintains natural stereo width. At 80%–100%, generates ultra-wide modern hyperpop doubles via multi-phase detuning. |
| Snap Speed | snap_speed |
0.0% – 100.0% | 0.0% | Quantize Glide Speed. Controls the pitch-snap transition curve in Quantize mode. At 0%, pitch glides smoothly with portamento; at 100%, delivers hard, instantaneous autotune snapping. |
| Robot Note | robot_note |
24 – 84 (C1 – C6) | 48 (C3) | Monotone Target Note. Sets the drone pitch for Robot Mode. Transposes the incoming vocal into a single, static robotic pitch (MIDI note 24 = C1 up to 84 = C6). |
| Mix | mix |
0.0% – 100.0% | 100.0% | Dry / Wet Balance. Blends unprocessed lead vocal with shifted output. Blend at 30%–45% for instant parallel vocal doubling without multiple takes. |
| Output Gain | output_gain |
-24.0 dB – +12.0 dB | 0.0 dB | Makeup Trim. Balances shifted vocal level against the rest of the lead vocal chain. |
3. Operating Modes & Musical Quantization
Pitch and formant shift freely by the exact semitones set on the knobs. Preserves the singer's natural vibrato and emotional contours. Best for ad-libs, octave backing vocals, and vocal character design.
Detects the incoming vocal pitch and automatically snaps shifted notes to your selected Musical Scale and Root Key. Supported scales: Chromatic, Major, Minor, Pentatonic Major/Minor, Dorian, and Blues.
Completely removes incoming melodic pitch contours and flattens the vocal onto a single target pitch designated by Robot Note. Creates robotic vocoder-style hooks and monotone EDM vocal drop chops.
4. Battle-Tested Mix Recommendations
Tuck an octave-lower double beneath your lead vocal to provide low-mid chest punch and weight without muddying the main track.
Acoustic Result: Imparts thickness and authority to thin lead vocals, anchoring them directly in modern pop and urban mixes.
Create an ultra-wide, sparkling vocal halo that shimmers in the stereo background without cluttering lead intelligibility.
Acoustic Result: Produces a shimmering, ultra-wide vocal top layer. Insert a high-pass filter (cut below 600 Hz) before AuxFormant on the bus for pristine clarity.
Transform melodic sliced vocal chops into an aggressive, rhythmically driving synthesizer hook locked to your track root key.
Acoustic Result: Vocal contours flatten into an edgy, hard-hitting robotic synth lead that locks in with your drop bass and drums.