convolution-reverb.js

const getImpulseBuffer = (audioCtx, impulseUrl) => {
    return fetch(impulseUrl)
    .then(response => response.arrayBuffer())
    .then(arrayBuffer => audioCtx.decodeAudioData(arrayBuffer))
}

const getLiveAudio = (audioCtx) => {
    return navigator.mediaDevices.getUserMedia({audio: true})
    .then(stream => audioCtx.createMediaStreamSource(stream));
} 

async function init(){
  const audioCtx = new AudioContext();
  const input = await getLiveAudio(audioCtx)
  const convolver = audioCtx.createConvolver()
  //lets assume there is an mp3 file in root of our project
  convolver.buffer = await getImpulseBuffer(audioCtx, '/impulse.mp3')
  
  input.connect(convolver).connect(audioCtx.destination)
}

init()