Does the buzzing occur both with your power supply plugged in and unplugged? Does it occur when your battery is unplugged and your power supply plugged in?
If you had the right speaker replaced, it's likely to be that speaker. Do you know how to unplug the speaker, or are you too novice to crack the case open?
Also, do the programs use various colors onscreen? It may be a board/circuit associated with your monitor.
I saw your response to the other guy's problem and I'm experiencing the same one on my VAIO VPCEB4Z1E.Yet I can see a difference when the laptop is plugged in - there is completely no buzzing or just a bit that doesn't bother me.So could you please tell me if you have any solution ?