Pitch shifter and harmonizer

What it is and how it works

• Pitch shifter: changes the pitch of a signal without changing its duration. Two families of algorithms: time domain (granular/PSOLA: cuts the signal into small grains and plays them closer together or further apart, excellent for monophonic sources like the voice) and frequency domain (phase vocoder: analyzes the spectrum and shifts it, better on polyphonic material but with "metallic" or "bubbly" artifacts on transients).
• Formants: the resonances of the vocal tract (or of an instrument's body) that give the timbre, independent of the note. A simple shift also moves the formants ("chipmunk" or "monster" effect); formant correction keeps them fixed for a natural result; shifting only the formants changes the perceived "size" and gender of a voice without changing the note.
• Harmonizer: generates one or more voices pitched relative to the original: at a fixed interval (always +3 semitones) or diatonic/intelligent (following key and scale, or chords via MIDI). The name comes from the Eventide H910 Harmonizer (1975); the H3000 became the standard for "micro-pitch".

Parameters one by one

• Pitch / Semitones / Cents: the shift. FL's Pitch Shifter goes from −12 to +12 semitones with semitone snapping on the slider and continuous movement on the X/Y pad.
• Formant / Formant correction: in Pitch Shifter (Voice engine), Formant shifts the formants; Formant Correction 0–100% decides how much they follow the pitch (0% = most natural).
• Algorithm / mode: Voice (monophonic) or Music (polyphonic, with grain Duration/Density/Jitter/Rand) in Pitch Shifter; in third-party plugins: Mono, Poly, Drums, Speech.
• Pitch mode: Relative (keeps the variations of the performance) or Absolute (flattens to a note that can be driven by automation or keyboard: robotic effect/new melody).
• Detection: Fast (28 ms) or Accurate (56 ms) in Pitch Shifter; affects latency and stability.
• Delay / Feedback: delay of the voices (pitched echoes) and repeats (pitch that rises on every pass).
• Mix: 0% dry, 100% shifted; for two-voice harmonies the manual suggests about 50%.
• Key / Scale / MIDI: for intelligent harmonizers (Pitcher, Antares Harmony Engine, Waves OVox, iZotope Nectar).
• Voices, pan, detune, humanize: number of voices, stereo position, small differences in pitch and timing for realism.

Tools

• FL Studio: Pitch Shifter (Voice/Music, formants, X/Y, delay and feedback, mix); Pitcher (real-time correction and MIDI-driven harmonization); Newtone (graphical pitch and time editing, useful for creating harmonies from a copy); Fruity Granulizer and Effector GRAIN; stretch and pitch of Audio Clips (time-stretch modes).
• Third-party: Soundtoys Little AlterBoy (pitch and formants), Eventide H910/H3000/MicroPitch, Waves SoundShifter and OVox, Antares Harmony Engine, Celemony Melodyne (hand-drawn harmonies), Zynaptiq PITCHMAP, Kilohearts Pitch Shifter, Auburn Graillon (free).

When to use it and on what

• Micro-pitch / stereo doubling: two copies at ±5/±12 cents, delayed 10–25 ms, panned L/R, at 15–30% level: wider vocals and synths without chorus vibrato (the H3000 trick).
• Octave down: vocal or lead with −12 st at 10–25% for weight (pop vocals, the "deep double" effect in hip hop and K-pop), deeper basses.
• Octave up: bright synths and guitars; ethereal vocals (very little).
• Harmonies: thirds and sixths above/below (diatonic) for filler choirs; better to record them or edit them in Melodyne/Newtone if exposed.
• Formants: "pitched" vocal in vocal-chop style (pitch +5/+12 and formants corrected or shifted), "demonic" voices (−5/−12 with formants down), changes of character on samples.
• Creative effects: pitch with feedback in a delay (rising echoes), risers with automated pitch, "tape stop", vocal chops.
• Sampling: changing the key of loops and samples to fit the song.

Starting settings

By genre

• Pop, K-pop: micro-pitch on vocals and choirs, octave down on choruses, vocal chops in drops.
• Hip hop, trap: pitched-down vocal for ad-libs and intros, transposed samples, formants for character.
• EDM, future bass: vocal chops with pitch and formants, synthetic harmonies.
• Rock and metal: octavers on guitars and bass, harmonizers for guitar harmonies (twin guitar style).
• Hyperpop: extreme pitches (+5/+12) with pushed formants.

Common mistakes

• Fixed, non-diatonic octaves or harmonies on melodies that change chord: wrong notes.
• Metallic artifacts with polyphonic algorithms on vocals: use Voice/Mono mode.
• Micro-pitch too loud: it sounds like an out-of-tune chorus.
• Not accounting for the latency of real-time pitch shifters while recording.
• Formants not corrected on large shifts (beyond ±3 st) when you want naturalness.

How to hear it

• Octave down: raise it from 0 until the voice sounds "bigger", stop before you hear a distinct second voice.
• Doubling: in mono the voice must not become louder or "phasey"; if it does, increase the delay or reduce the level.