ConvolverNode: buffer property

The buffer property of the ConvolverNode interface represents a mono, stereo, or 4-channel AudioBuffer containing the (possibly multichannel) impulse response used by the ConvolverNode to create the reverb effect.

This is normally a simple recording of as-close-to-an-impulse as can be found in the space you want to model. For example, if you want to model the reverb in your bathroom, you might set up a microphone near the door to record the sound of a balloon pop or synthesized impulse from the sink. That audio recording could then be used as the buffer.

This AudioBuffer must have the same sample-rate as the AudioContext or an exception will be thrown. At the time when this attribute is set, the buffer and the state of the attribute will be used to configure the ConvolverNode with this impulse response having the given normalization. The initial value of this attribute is null.

const audioCtx = new (window.AudioContext || window.webkitAudioContext)();
const convolver = audioCtx.createConvolver();

// …

// grab audio track via XHR for convolver node

let soundSource;
let concertHallBuffer;

ajaxRequest = new XMLHttpRequest();
ajaxRequest.open("GET", "concert-crowd.ogg", true);
ajaxRequest.responseType = "arraybuffer";

ajaxRequest.onload = () => {
  const audioData = ajaxRequest.response;
  audioCtx.decodeAudioData(
    audioData,
    (buffer) => {
      concertHallBuffer = buffer;
      soundSource = audioCtx.createBufferSource();
      soundSource.buffer = concertHallBuffer;
    },
    (e) => console.error(`Error with decoding audio data: ${e.err}`)
  );
};

ajaxRequest.send();

// …

convolver.buffer = concertHallBuffer;