On GotSound.org we are using wavesurfer.js to play sounds in a browser.
It's works only in modern browsers supporting Web Audio.
MediaElement fallback to support old browsers like Internet Explorer not always works.
You can find more information about browser supported Web Audio API here.
Please, consider to upgrade your browes to one of the following:
Marching bassline. Cinematic, intro, music bed ,song layering... video games development. 120 bpm. Recorded in Cubase.My profile-info/other stuff.