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 canadian man vocalizes his feelings on a variety of missions including Sophie by radioing her and continually sharing different emotions. I Love Sophie 100908989789797987089098777777% I am showing support for the ocean and for the Marines!