Mozilla is only now starting to work on Web Audio API, some components have landed in the Nightly channel Firefox, but it's still going to be a while before support is good enough for any actual app to use the feature in Firefox.
At least Mozilla has gotten to it and now, it's highlighting
, Howler.js, provides an abstraction layer between the app, it's designed mostly for games, and the audio API, either basic HTML5 audio or the Web Audio API.
By default, it tries to use Web Audio API; but if it's not supported, it reverts to HTML5 audio. The beauty of this is that developers will only have to write code once and the library will handle the messy part.