Listen to Playback Rate Changes in Howler.js

This article provides a quick and clear guide on how to listen for changes in the audio playback rate using the Howler.js library. You will learn how to utilize the library’s built-in event system to detect when the playback speed changes and retrieve the new rate programmatically.

In Howler.js, you can listen for changes to the playback rate by using the on method to bind a listener to the 'rate' event. This event triggers whenever the rate() method is called on a Howl instance or an individual sound ID.

Step-by-Step Implementation

To listen for playback rate changes, register the 'rate' event listener on your Howl instance. Inside the callback function, you can retrieve the updated rate using the rate() method.

Here is a complete, straight-to-the-point code example:

// 1. Initialize the Howl sound object
const sound = new Howl({
  src: ['audio.mp3'],
  html5: true // Works with both Web Audio API and HTML5 Audio
});

// 2. Register the 'rate' event listener
sound.on('rate', function(soundId) {
  // Retrieve the current playback rate for the specific sound
  const currentRate = sound.rate(soundId);
  console.log(`Playback rate changed to: ${currentRate} for sound ID: ${soundId}`);
});

// 3. Play the sound
sound.play();

// 4. Change the rate (this will trigger the event listener above)
setTimeout(() => {
  sound.rate(1.5); // Increase speed to 1.5x after 2 seconds
}, 2000);

Key Considerations