stereoPanner-test.js

const fs = require('fs');
module.exports = (audioContext) => {
  const buffer = fs.readFileSync('/tmp/MixTwoDifferentChannels.wav');

  return audioContext.decodeAudioData(buffer).then((audioBuffer) => {

    const bufSrc = audioContext.createBufferSource();
    const panNode = audioContext.createStereoPanner();

    // mostly on the left
    panNode.pan.value = 0.9;

    // if channelCount is set to 2 it fails to apply the correct panning.
    panNode.channelCount = 1;

    bufSrc.buffer = audioBuffer;
    bufSrc.connect(panNode);
    panNode.connect(audioContext.destination);
    bufSrc.start(0);
  });
};