Time Polyphony - 8 Channels — User Guide

Creates 8 copies of a Sound object with different time-stretching factors and combines them into an 8-channel output using Phase Vocoder synthesis.

Category: Synthesis / Processing Praat Script: Time Polyphony - 8 Channels.praat

Contents:

What this does Quick start Presets Parameters Outputs

What this does

This Praat script generates complex, multi-layered textures by creating eight independent voices from a single source sound, each subject to a unique time-stretching factor. The Phase Vocoder algorithm is used to perform the time-stretching without altering the original pitch. The eight processed mono voices are then combined into a single 8-channel output sound object.

The core process involves:

Cloning and Manipulation: Creating a Manipulation object for each of the eight channels from the original Sound.
Duration Tiers: Creating a DurationTier for each channel and setting a constant Time_scale value across the entire original duration. This value determines the speed of that specific voice.
Resynthesis: Generating the time-stretched/compressed sound via resynthesis (overlap-add).
Multi-channel Combination: Iteratively combining the eight resultant mono sounds into a single 8-channel Sound object.
Scaling: The final output is scaled to a peak of 0.99 to prevent clipping.

Time Scale Interpretation:

The Time_scale value determines the duration of the output for that channel.

1.0: Normal speed.
> 1.0: Slower (time-stretched).
< 1.0: Faster (time-compressed).

Quick start

In Praat, select a Sound object.
Run script… → Time Polyphony - 8 Channels.praat.
Choose a Preset (e.g., "Slow Motion") or set the eight individual Time_scale values.
Click OK.
The output object, named [OriginalName]_polyphony_8ch, appears and plays automatically if the Play_result option is checked.

Presets

The script offers seven predefined presets to quickly generate different sonic textures by setting the eight Time_scale values:

Preset Name	Channel Time Scales
Classic Polyphony	1.0, 1.15, 0.85, 1.3, 0.7, 1.1, 0.9, 1.2
Slow Motion	1.5, 1.7, 1.3, 1.6, 1.4, 1.8, 1.2, 1.9
Fast Chaos	0.5, 0.6, 0.4, 0.7, 0.3, 0.8, 0.2, 0.9
Rhythmic Pulse	1.0, 0.5, 1.0, 0.5, 1.0, 0.5, 1.0, 0.5
Subtle Variation	1.0, 1.05, 0.98, 1.02, 0.95, 1.03, 0.97, 1.01
Extreme Stretch	3.0, 2.5, 3.5, 2.0, 4.0, 2.2, 3.8, 2.7
Glitch Matrix	0.1, 0.8, 0.3, 1.5, 0.2, 1.2, 0.4, 2.0

Parameters (form fields)

Name (GUI)	Type	Default (Classic Polyphony)	Description
Preset	optionmenu	Classic Polyphony	Selects a predefined set of `Time_scale` values.
Time_scale_1	real	1.0	Time scale factor for Channel 1.
Time scale 2	real	1.15	Time scale factor for Channel 2.
Time_scale_3	real	0.85	Time scale factor for Channel 3.
Time_scale_4	real	1.3	Time scale factor for Channel 4.
Time_scale_5	real	0.7	Time scale factor for Channel 5.
Time_scale_6	real	1.1	Time scale factor for Channel 6.
Time_scale_7	real	0.9	Time scale factor for Channel 7.
Time_scale_8	real	1.2	Time scale factor for Channel 8.
Play_result	boolean	1 (checked)	If checked, the resulting sound plays automatically after processing.

Outputs

Object name: [OriginalName]_polyphony_8ch
Type: Sound (8-channel)
Normalization: Peak-scaled to 0.99
Requirement: Requires a selected Sound object to run.