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:
A rather long track. Nothing much happens, apart from a few cars, wind in a birchtree, someone walking by, some birds, all in all pretty suburbish. All that recorded in Esbjerg / Denmark in August 2011, using 2 Sennheiser MKH60 microphones into Oade FR2-le.