How do I redirect sound card output to file
 

Ok, so here's the situation. I'm using FC2 (2.6.6-1.435.2.3) and Firefox. There's a site where I get audio playing in a popup. First question, which sound device is the audio coming through? And second, how can I redirect that audio to a file? I've tried running the following command:
which states that it's recording but no file is crated. Am I completely off on all this? Can this even be done? I'd appreciate any help at all. Thanks in advance.