ConvolverNode: normalize property

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since ⁨July 2015⁩.

The normalize property of the ConvolverNode interface is a boolean that controls whether the impulse response from the buffer will be scaled by an equal-power normalization when the buffer attribute is set, or not.

Its default value is true in order to achieve a more uniform output level from the convolver, when loaded with diverse impulse responses. If normalize is set to false, then the convolution will be rendered with no pre-processing/scaling of the impulse response. Changes to this value do not take effect until the next time the buffer attribute is set.

const audioCtx = new AudioContext();
// …

const convolver = audioCtx.createConvolver();
// …

// Grab audio track via fetch() for convolver node
try {
  const response = await fetch(
    "https://mdn.github.io/voice-change-o-matic/audio/concert-crowd.ogg",
  );
  const arrayBuffer = await response.arrayBuffer();
  const decodedAudio = await audioCtx.decodeAudioData(arrayBuffer);
  convolver.normalize = false; // must be set before the buffer, to take effect
  convolver.buffer = decodedAudio;
} catch (error) {
  console.error(
    `Unable to fetch the audio file: ${name} Error: ${err.message}`,
  );
}