Hi, I'm one of the Web Audio API developers at Mozilla. This demo uses a very old version of the Web Audio API, that we don't support, because it is not standard (and we started to implement after the breaking changes in the spec anyways).
Standard compliant Web Audio API is available from Firefox 25,
It does here! (I'm running Nightly on OXS). I met Paul Lamere the other day at the music hack day in Barcelona and he told me he updated his numerous demos so that they use the new spec.
Standard compliant Web Audio API is available from Firefox 25,