Disable deprecated Audio Data API
iSec pointed out that the Audio Data API was superceded by the WebAudio API, but it remains on by default in the Firefox 24ESR series. This is bad for business, especially given how many vulnerabilities have been in WebAudio. There is a risk that similar vulnerabilies have simply gone unfixed in AudioData.
https://bugzilla.mozilla.org/show_bug.cgi?id=927245
The pref is media.audio_data.enabled.