fined') {
			audio = new AudioContext();
		}
		else if (typeof webkitAudioContext !== 'undefined') {
			audio = new webkitAudioContext();
		}
	}
	audioEnable()
	if (audio && !audioNode) {
		const bufferSize = // set bufferSize according to environment's samplerate
		audio.sampleRate <  64000 ? 2048 : // for 48000hz or 44100hz or less
		audio.sampleRate < 128000 ? 4096 : 8192; // for 96000hz or more
		audioNode = audio.createScriptProcessor(bufferSize, 1, 1);
		audioNode.gain = audio.createGain();
		audioNod