유튜브 소리 작아서 속터질때

var videoElement = document.querySelector("video");
var audioCtx = new AudioContext();
var em_source = audioCtx.createMediaElementSource(videoElement);
var gainNode = audioCtx.createGain();
gainNode.gain.value = 3; ★
em_source.connect(gainNode);
gainNode.connect(audioCtx.destination);