I have added both mp3 and ogg sound files in my project. They work fine on Chrome, Safari, FF and Opera. But same sounds are not properly played on IE9.
Someone has something about it? I have the same problem with IE9, I'm working with cocos2d JS 3.3 and made some test with 3.6 and neither.
I think ie9 only plays mp3 idk if this helps in any way.