AudioContext not loading in Internet Explorer

EDIT: Just thought it would be worth mentioning, I'm not sure if putting window.AudioContext is important but it seems to have had zero effect.

I am using a visualiser that uses AudioContext to get frequency data. It doesn't work in Internet explorer.

A previous Stack Overflow question was somewhat relevant:

HTML5 How to replace WebAudio API for Internet Explorer for javascript games?

So, I am using the following code to get the AudioContext

function audioContextCheck() 
{
if (typeof window.AudioContext !== "undefined") {
    console.log('AudioContext');
    return new window.AudioContext();
} else if (typeof webkitAudioContext !== "undefined") {
    console.log('webkitAudioContext');
    return new window.webkitAudioContext();
} else if (typeof window.mozAudioContext !== "undefined") {
    console.log('mozAudioContext');
    return new window.mozAudioContext();
} else {
   console.log('NONE OF THEM!');
}
}

The console returns 'NONE OF THEM', meaning that Internet Explorer (version 11) is unable to load any of the audio thingies.

Microsofts own doccumentation refers to AudioContext(): http://ift.tt/2e5SQtT

I am very confused, am I missing something?