[ubuntu] HP audio problem (crack sound)

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http://ubuntuforums.org – Hi. I've got a dv-6000 hp computer (2007 aprox) and I had on it Vista. After I decidid to install Windows 7 and ubuntu 12.04. Everything is working fine in Windows and in Ubuntu but I have a problem with the audio in Ubuntu. Every time I start in Ubuntu sounds through the speakers a little crack sound when the deskop it's just loaded. Then this annoying crack continues ever half second aproximately. The thing is that when I reproduce anything (mp3 or a video on youtube) that crack sound stops, and when the audio is finished it reapperas. I googled the problem and I found that I should change (Hardware)