Subwoofer Problem

Hey there, I've bought my computer nearly a year now, last September and now I've got a problem with the subwoofer I think, it keeps distracting the sounds with a noise and I have to keep it mute all the times. I don't know what's the problem is but  there must be something wrong with it. 

Anyone knows how to fix it or I have to take it to the Dell Centre..?

Thanks.