I realized that there is a red light coming out of my earphone jack. It's something like this: http://i.stack.imgur.com/gokuH.jpg
I looked in the folder that Toshiba created for installing drivers , then I found out that they had installed this driver for my sound card: Realtek HD Audio Driver v188.8.131.5289_withMaxxAudio_Compal(20080908)
I'm guessing that the sound card supports Optical Audio Output. I also found out that when I mute the speakers, the light goes away. But when I unmute it, it comes back.
I don't really mind having it but it drains my battery. So, is there a Ubuntu version for my sound card driver?