onal - if you don't set an audioContext, then abcjs will create one.
					window.AudioContext = window.AudioContext ||
						window.webkitAudioContext ||
						navigator.mozAudioContext ||
						navigator.msAudioContext;
					var audioContext = new window.AudioContext();
					audioContext.resume().then(function () {
						// In theory the AC shouldn't start suspended because it is being initialized in a click handler, but iOS seems to anyway.

						// This does a bare minimum so this object could be create