User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:18.0) Gecko/20100101 Firefox/18.0 Build ID: 20130116073211 Steps to reproduce: On http://www.definitions.net/definition/mademoiselle Clicked on "Say it" (the small picture of a speaker). Actual results: Nothing. Expected results: Say something. It works in IE.

works with media.windows-media-foundation.enabled on trunk builds and they are using audio/mpeg So this depends on bug 799318 (mp3 support in desktop Firefox)