Pitch Correction — User Guide

Phase Vocoder-Based Auto-Tune Effect: High-quality pitch correction using phase vocoder and PSOLA methods with vibrato removal, scale correction, and transposition.

Author: Shai Cohen Affiliation: Department of Music, Bar-Ilan University, Israel Version: 0.1 (2025) License: MIT License Repo: https://github.com/ShaiCohen-ops/Praat-plugin_AudioTools

Contents:

What this does Quick start Presets Implementation Details

What this does

This script implements professional-grade pitch correction similar to Auto-Tune. It analyzes the pitch contour of a sound, corrects it to the nearest notes in a selected musical scale, and resynthesizes the audio while preserving formants and timbral characteristics.

Key Features:

6 Built-in Presets – From natural/subtle to extreme Auto-Tune effect
Two Processing Methods – Phase Vocoder (highest quality) or PSOLA (faster)
Multiple Scales – Chromatic and 12 major/minor keys
Vibrato Removal – Enhanced and ultra smoothing methods
Adjustable Correction Strength – 0-100% for natural to robotic results
Transposition – Shift pitch by semitones while correcting
Formant Preservation – Maintains vocal character and timbre
Reference Tuning – A4=440Hz, 432Hz, or C4=261.63Hz

Quick start

In Praat, select a Sound object (works best with pitched audio: vocals, melodic instruments)
Run script… → Load this script file
A dialog appears with preset dropdown and parameters
Quick option: Choose a preset (e.g., "Balanced Correction") and click OK
Custom option: Select "Custom" and adjust all parameters manually
Script analyzes pitch, corrects to selected scale, and resynthesizes audio
Progress is displayed in the Info window throughout processing
The resulting corrected Sound object is created in the Objects window.

Quick Tip: Start with Balanced Correction for general use. Use Natural and Subtle for preserving expressive performance. Try Maximum Auto-Tune for creative effects. Adjust Correction Strength (0-100%) to control how aggressively pitches are corrected. Lower values preserve more of the original performance. Set Transposition to shift the entire melody up/down by semitones.

Important: This script works best with monophonic pitched audio (single melodic line: vocals, solo instruments). It may produce artifacts on: polyphonic material (chords, harmonies), unpitched sounds (percussion, noise), or very breathy/whispery vocals. Processing time: Phase Vocoder is slower but higher quality; PSOLA is faster but may have more artifacts. Adjust Min/Max Pitch Hz based on your source (male vocals: 75-300Hz, female vocals: 150-600Hz, instruments: adjust accordingly).

Presets

Six built-in presets provide quick access to common pitch correction styles:

Preset Name	Vibrato	Correction	Smoothness	Character
Custom	–	–	–	Full manual control
Natural and Subtle	Off	50%	High (8)	Gentle pitch nudging, preserves expression
Balanced Correction	On	75%	Medium (6)	Clear tuning, natural sound
Strong Correction	On	90%	Low (4)	Tight pitch control, slight robotic quality
Maximum Auto-Tune	On	100%	Very Low (2)	Hard-tuned, T-Pain/Cher effect
Vibrato Removal Only	On	0%	Maximum (10)	Removes vibrato without pitch correction

Natural and Subtle

Use case: Gentle pitch correction for natural-sounding vocal enhancement

Correction strength: 50% (partial correction)
Vibrato: Preserved (off)
Transition smoothness: 8/10 (very smooth)

Result: Subtle pitch nudging that maintains expressive qualities and natural vibrato. Imperceptible correction for slight tuning issues.

Balanced Correction

Use case: Standard pitch correction for professional vocal production

Correction strength: 75% (strong but natural)
Vibrato: Removed (enhanced smoothing)
Transition smoothness: 6/10 (balanced)

Result: Clear pitch correction that sounds natural. Removes vibrato while maintaining vocal character. Ideal for pop/rock production.

Strong Correction

Use case: Tight pitch control with slight robotic quality

Correction strength: 90% (near-perfect tuning)
Vibrato: Removed (enhanced smoothing)
Transition smoothness: 4/10 (faster transitions)

Result: Very accurate pitch correction with minimal deviation. Slight robotic character emerges. Good for modern pop/EDM vocals.

Maximum Auto-Tune Effect

Use case: Extreme hard-tuned effect (T-Pain, Cher, Travis Scott style)

Correction strength: 100% (perfect tuning)
Vibrato: Removed (ultra smoothing)
Transition smoothness: 2/10 (fast snapping)
Time step: 0.005 (very detailed)

Result: Characteristic robotic Auto-Tune effect with instant pitch snapping. Dramatic, artificial sound. Perfect for creative effects.

Vibrato Removal Only

Use case: Remove vibrato without changing pitch

Correction strength: 0% (no pitch correction)
Vibrato: Removed (ultra smoothing, strength 9)
Transition smoothness: 10/10 (maximum)

Result: Smooths out pitch fluctuations and vibrato while maintaining the original melodic contour. Useful for analysis or creating flat vocal tones.

Implementation Details

Fixed Analysis Parameters

The script's analysis relies on the following fixed and configurable parameters, which determine the quality and character of the pitch correction:

Parameter	Range / Options	Default Preset Value	Function
Pitch Min/Max Hz	75 Hz - 600 Hz	75 Hz / 600 Hz	Defines the F0 search range for the pitch extraction algorithm.
Reference Tuning	A4=440 Hz, A4=432 Hz, C4=261.63 Hz	A4=440 Hz	Sets the standard tuning used for calculating target pitches.
Scale	Chromatic, 12 Major/Minor Keys	User Selected	Determines the set of target notes for pitch correction.
Correction Strength	1 - 100 %	80 % (Custom)	Controls the degree of correction applied (100% is hard-tuned).
Processing Method	Phase Vocoder or PSOLA	Phase Vocoder	Selects the resynthesis engine; Phase Vocoder provides superior quality.
Pitch Time Step	0.005 s - 0.02 s	0.01 s (Custom)	The time resolution of the F0 analysis; smaller values capture more detail but increase processing time.