Auto‑Harmonic Layering (Enhanced) — User Guide

One‑step loop harmonizer with enhanced features: automatically detects repeating pitch patterns and applies chord‑based harmonization with individual voice control, smooth fades, and flexible output options.

Technique: Loop Detection + Pitch‑Shift Harmonization Implementation: Praat Script Category: Creative Audio Processing Version: 0.3 Enhanced Algorithm: Turbo Pitch Loop Finder + Interval‑Based Harmonization

✨ New in v0.3:

Individual Chord Level Control: Adjust root, 2nd, and 3rd voice volumes independently
Smooth Fade Envelopes: Automatic fade-in/fade-out on chords for seamless blending
Consistent Chord Assignment: Each loop keeps the same chord across all its repeats
Harmonization Scope Controls: Choose to harmonize only loops or limit to time range
Mono Output Option: Convert final mix to mono for single-channel compatibility

Contents:

What this does New Features Quick start Three‑Phase Workflow Harmonization Methods Interval Mathematics Parameters Output & Results Applications

What this does

This script implements a complete audio harmonization pipeline that (1) automatically detects repeating pitch patterns (loops) in monophonic audio, then (2) applies chord‑based harmonization to those loops to create rich, layered textures. Unlike simple pitch‑shifting or harmonizer effects, this intelligently identifies meaningful repetitions (melodic motifs, phrases, patterns) and applies musically‑informed chord voicings (octaves, fifths, triads) to transform monophonic sources into harmonically rich arrangements.

Key Features:

Two‑Step Processing: Loop detection → intelligent harmonization
7 Chord Types: Octave doubling, fifth (power chord), major, minor, sus4, sus2, random
Individual Voice Control: Adjust root, 2nd, and 3rd note levels independently (0-1)
Smooth Fade Envelopes: Automatic fade-in/out prevents clicks, ensures seamless blending
Consistent Loop Chords: Each loop number maintains same harmony across all repeats
Flexible Scope: Harmonize loops only, repeats only, or limit by time range
Automatic Pattern Recognition: Finds meaningful repetitions, not just fixed‑time loops
Smart Mixing: Preserves original audio, blends harmonies at adjustable volume
Dual Output Modes: Stereo (original + chords) or Mono (mixed together)
Turbo Optimization: Fast matrix‑based loop detection (C++ engine)
Clean Workflow: Removes all temporary objects, leaves only final result

What is loop‑based harmonization? Traditional harmonizers: apply constant pitch shifts to entire audio. Loop‑based harmonization:

Selective: Only harmonizes repeating patterns (not everything)
Musical: Uses chord intervals (3rds, 5ths, octaves) not just random shifts
Context‑aware: Harmonizes loops where they actually repeat
Layered: Creates three‑voice chords from single‑voice source
Controllable: Each voice (root, 2nd, 3rd) has independent volume control
Smooth: Automatic fades prevent abrupt starts/stops
Creative: Turns monophonic material into rich, evolving textures

Ideal for: vocal harmonization, melody enrichment, texture creation, experimental sound design.

Technical Pipeline: Phase 1: Loop Detection — Extract pitch contour, compute similarity matrix, find diagonal patterns, annotate loops in TextGrid, assign consistent chord to each loop number. Phase 1B: Chord Assignment — Each loop number gets one chord type (all repeats share it). Phase 2: Harmonization — Extract loop segments, apply interval‑based pitch‑shifting with individual voice levels, apply fade envelopes, reconstruct timeline. Phase 3: Mixing — Blend harmonized track with original, output as stereo or mono. Uses Praat's Manipulation objects for high‑quality pitch‑shifting.

New Features (v0.3)

1. Individual Chord Level Control

🎚️ Independent Voice Volume Control

Parameters:

Root_level (0-1, default 1.0) — Volume of original pitch
Note_2_level (0-1, default 0.8) — Volume of 2nd interval
Note_3_level (0-1, default 0.6) — Volume of 3rd interval

Creative uses:

Prominent root: 1.0 / 0.6 / 0.4 — Melody leads, harmonies subtle
Balanced triad: 0.8 / 0.8 / 0.8 — Equal voices
Upper voice emphasis: 0.7 / 1.0 / 0.9 — Highlights harmony
Hollow fifth: 0.9 / 0.2 / 0.8 — De-emphasize middle note

Example: For major chord (root + 4 + 7 semitones), setting levels to 1.0 / 0.7 / 0.5 creates a natural voicing where upper notes support but don't overpower the melody.

2. Smooth Fade Envelopes

🌊 Automatic Fade-In/Fade-Out

Parameters:

Fade_duration (seconds, default 0.01) — Length of fade-in and fade-out
Apply_fades (checkbox, default ON) — Toggle fades on/off

How it works:

Fade-in applied to start of each chord segment
Fade-out applied to end of each chord segment
Automatic limiting: fade never exceeds 25% of segment duration
Prevents clicks/pops when chords start or end
Creates seamless blending with melody

Recommended settings:

Subtle blending: 0.015 - 0.02s (smooth, unnoticeable)
Percussive: 0.005 - 0.01s (sharper attack)
Ambient: 0.03 - 0.05s (very smooth, pad-like)

3. Consistent Chord Assignment

🎯 Same Loop = Same Chord

In previous versions, each event (Loop 1, Repeat 1, Repeat 2...) could get different random chords. Now:

Loop 1 assigned (e.g.) Major → All Repeat 1 instances also get Major
Loop 2 assigned (e.g.) Minor → All Repeat 2 instances also get Minor
Creates harmonic coherence: same melodic pattern always has same harmony
Makes musical sense: listeners recognize the pattern and its harmony

Example: If your melody has a motif that repeats 3 times, all 3 instances will have the same chord voicing, creating a unified harmonic identity for that motif.

4. Harmonization Scope Controls

📍 Control What Gets Harmonized

Parameters:

Parameter	Type	Default	Purpose
`Harmonize_repeats`	Checkbox	ON	Include "Repeat" intervals in harmonization
`Harmonize_until_time`	Seconds	0 (full)	Only harmonize events before this time

Use cases:

Loops only: Uncheck Harmonize_repeats to process only original loops
Time-limited: Set Harmonize_until_time to 6.0 to stop harmonization at 6 seconds
Solve "harmony after melody ends": If melody fades/ends at 8s but repeats occur later, set limit to 8.0

5. Mono Output Option

🔊 Flexible Output Formats

Output_mono (checkbox, default OFF)

OFF (Stereo): Original in left channel, harmonies in right channel — allows separate control in DAW
ON (Mono): Original + harmonies mixed together in single channel — simpler, single-track output

When to use mono: Broadcasting, podcasts, phone playback, or when you want harmonies fully integrated with original.

When to use stereo: Music production (for further mixing), creative panning effects, or when you want to adjust balance later.

Quick start

In Praat, select exactly one Sound object (monophonic material works best).
Run script… → auto_harmonic_layering_enhanced.praat.
Set Loop Detection parameters (or keep defaults):
- Time_step: 0.05s (fast) or 0.02s (precise)
- Pitch_floor/ceiling: Match your audio's pitch range
- Tolerance_hz: 30‑50 Hz for speech, 50‑100 Hz for expressive music
- Num_loops_to_find: 3‑10 depending on density
Choose Chord_Type:
- Octave Doubling: Thick, orchestral (root + octave + 2 octaves)
- Fifth: Power chord, rock/metal (root + fifth + octave)
- Major/Minor: Traditional triads
- Sus4/Sus2: Suspended, ambiguous harmonies
- Random: Mix of all types for variation
NEW: Set Chord Mixing Levels:
- Root_level: 1.0 (full volume for melody)
- Note_2_level: 0.8 (slightly quieter 2nd voice)
- Note_3_level: 0.6 (quieter 3rd voice for depth)
NEW: Configure Envelope Settings:
- Fade_duration: 0.01s (default, subtle fades)
- Apply_fades: Check ON for smooth blending
NEW: Set Harmonization Scope:
- Harmonize_repeats: Keep ON to harmonize both loops and repeats
- Harmonize_until_time: 0 for full duration, or set to limit (e.g., 10.0)
Set Mix_volume: 0.3‑0.7 (overall harmony loudness).
NEW: Choose Output_mono: OFF for stereo, ON for mono.
Click OK — script runs three phases (watch Info window).
Output: Final_Mix_Stereo or Final_Mix_Mono.
Also creates: Harmonized_Track (harmonies only).
Sound auto‑plays after processing.

🎯 Recommended Presets

Subtle Background Harmonies:

Chord: Major or Minor
Root/Note2/Note3: 1.0 / 0.6 / 0.4
Fade: 0.015s, ON
Mix_volume: 0.4
Output: Mono

Bold Power Chord Effect:

Chord: Fifth
Root/Note2/Note3: 0.8 / 1.0 / 0.9
Fade: 0.008s, ON
Mix_volume: 0.6
Output: Stereo

Ambient Pad Texture:

Chord: Sus4 or Random
Root/Note2/Note3: 0.7 / 0.8 / 0.7
Fade: 0.03s, ON
Mix_volume: 0.5
Harmonize_until_time: Set to where melody ends
Output: Stereo

Complete Parameter Reference

Loop Detection Settings

Parameter	Range/Type	Default	Description
`Time_step`	0.01 - 0.1s	0.05s	Analysis frame rate. 0.05 = fast, 0.02 = precise
`Pitch_floor`	50 - 200 Hz	75 Hz	Minimum detectable pitch
`Pitch_ceiling`	300 - 1500 Hz	600 Hz	Maximum detectable pitch
`Tolerance_hz`	10 - 200 Hz	50 Hz	Pitch similarity threshold for loop detection
`Min_loop_duration`	0.1 - 5.0s	0.4s	Minimum loop length to detect
`Max_loop_duration`	1.0 - 60.0s	10.0s	Maximum loop length (optimization limit)
`Num_loops_to_find`	1 - 20	5	How many top loops to detect

Harmonization Settings

Parameter	Range/Type	Default	Description
`Mix_volume`	0.0 - 1.0	0.5	Overall harmony track volume (peak scaling)
`Chord_Type`	Choice menu	Random	Octave/Fifth/Major/Minor/Sus4/Sus2/Random

Harmonization Scope NEW

Parameter	Type	Default	Description
`Harmonize_repeats`	Boolean	ON	Include "Repeat" tier intervals in harmonization
`Harmonize_until_time`	0 - duration	0 (full)	Stop harmonizing after this time (0 = no limit)

Chord Mixing Levels NEW

Parameter	Range	Default	Description
`Root_level`	0.0 - 1.0	1.0	Volume of original pitch (root note)
`Note_2_level`	0.0 - 1.0	0.8	Volume of 2nd interval in chord
`Note_3_level`	0.0 - 1.0	0.6	Volume of 3rd interval in chord

Envelope Settings NEW

Parameter	Range/Type	Default	Description
`Fade_duration`	0.001 - 0.1s	0.01s	Length of fade-in and fade-out (auto-limited to 25% of segment)
`Apply_fades`	Boolean	ON	Enable/disable automatic fade envelopes

Output Format NEW

Parameter	Type	Default	Description
`Output_mono`	Boolean	OFF	Convert final mix to mono (ON) or keep stereo (OFF)

Output & Results

Created Objects

Object	Description	Use
`Final_Mix_Stereo`	Stereo mix: original (L) + harmonies (R)	Main output when `Output_mono = OFF`
`Final_Mix_Mono`	Mono mix: original + harmonies combined	Main output when `Output_mono = ON`
`Harmonized_Track`	Harmonies only (mono)	Export separately for mixing, or listen to harmony layer alone

💡 Working with Output:

Export stems: Save both Final_Mix and Harmonized_Track for DAW mixing
Adjust balance: In stereo mode, pan/volume control each channel separately
Further processing: Apply EQ, reverb, compression to harmony track independently
Layer multiple passes: Process same audio multiple times with different chord types, then blend

Info Window Output

The script reports:

Number of loops found
NEW: Chord assignment for each loop number (e.g., "Loop 1: Major, Loop 2: Minor")
NEW: Number of events skipped (if using harmonization scope limits)
NEW: Harmonization end time (if limited)
Number of events harmonized
NEW: Fade duration (if enabled)
NEW: Output format (Mono/Stereo)