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[Note]: Check out the AudioWorklet implementation of SoundTouchJS

SoundTouchJS is an ES2015 library of audio context utilities, converted, expanded, and maintained by Cutter. Read the backstory. To see it in action:

Edit SoundTouchJS with React

Or, clone the repo and Run The Example.


You can easily install SoundTouchJS for use in your project:

npm install soundtouchjs

General Usage

You can use whatever method you prefer to get your audio file, but once you have the data you must decode it into an AudioBuffer. Once you've decoded the data you can then create a new PitchShifter.

import { PitchShifter } from 'soundtouchjs';

const audioCtx = new (window.AudioContext || window.webkitAudioContext)();
const gainNode = audioCtx.createGain();
let shifter;

// here you retrieved your file with 'fetch' or a new instance of the 'FileReader', and from the data...
if (shifter) {; // remove any current listeners
audioCtx.decodeAudioData(buffer, (audioBuffer) => {
  shifter = new PitchShifter(audioCtx, audioBuffer, 1024);
  shifter.on('play', (detail) => {
    // do something with detail.timePlayed;
    // do something with detail.formattedTimePlayed;
    // do something with detail.percentagePlayed
  shifter.tempo = 1;
  shifter.pitch = 1;

To begin playback you connect the PitchShifter to the WebAudio destination (or another node), and disconnect it to pause. It's important to note that the PitchShifter is a pseudo-node, and cannot be connected to.

const play = function () {
  shifter.connect(gainNode); // connect it to a GainNode to control the volume
  gainNode.connect(audioCtx.destination); // attach the GainNode to the 'destination' to begin playback

Running The Example

An example has been included with the package to see some basic functionality. Prior to running the example you must install all dependencies.

npm i

If you've cloned the library, you need to build the code.

npm run build

It has been written in pure javascript, but could easily be integrated with your favorite framework.

Note: Run the example in a modern browser, as it uses es2015 import syntax.

To run the example:

npm start

then open your browser to http://localhost:8080. A royalty free music file is included under Creative Commons License with this repository.

Music: "Actionable" from

This is a limited use license, and we do not grant any permissions beyond theirs. Please refer to their licensing for further information.

All core components of the package are available as separate entities for more advanced audio manipulations. See the source code for greater understanding.

Creating Your Own Build

As long as you've installed all dependencies, you can run the build script to create your own local version of SoundTouchJS. This is good when contributing changes back to the project.

npm run build


If you want to contribute, Hooray! Just fork the repo, do your work in a branch, then submit a Pull Request when you're done. Code? Documentation? More Examples? Go for it!

Or maybe you just like what's been done? I accept cash


  • audio worklets - (Thank You to Janick Delot for sponsoring this upcoming feature)

In Case You Are Interested

SoundTouchJS is based on the C++ implementation of Soundtouch by Olli Parviainen. The earliest implementation in JavaScript was written by Ryan Berdeen and later expanded by Jakub Faila. I have further expanded this library into a distributable package, refactored for es2015 development.

This package includes the getWebAudioNode utility written by Adrian Holovaty, as well as the user-friendly PitchShifter wrapper from Jakub Faila.



A JavaScript library for manipulating WebAudio Contexts, specifically for time-stretching a pitch change







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