os audios dos flashcards estão mudos?

There are actually some bugs in IE 9 and Firefox 13 that prevent text-to-speech from working properly. We plan to have these fixed in the next update, but in the meantime I recommend downgrading to Firefox 12 or using Google Chrome.

For more information, please see this thread: No Text To Speech Audio - Language Forum @ LingQ

Aqui FF 12 ta funcionando normalmente.