Sony Vaio - Sound not working 100%

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https://bbs.archlinux.org – I installed arch linux on my brothers computer. I am using XFCE. The problem is, sound doesn't work right. Sometimes it does, sometimes it doesn't. It doesn't work more times than it does. Usually all he has to do is CTRL+ALT+BACKSPACE to get it fixed, but sometimes it doesn't fix it. I have not installed ANY sound drivers or anything. On the installation guide it said alsa works out of the box. It says he has an Intel Corporation 82801I (ICH9 Family) HD Audio Controller. I decided to install alsa-firmware (thinking it might help), but it didn't do anything. Please hel (HowTos)